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GCC(1) GNU Tools GCC(1) N✓NA✓AM✓ME✓E gcc, g++ - GNU project C and C++ Compiler (v2.6) S✓SY✓YN✓NO✓OP✓PS✓SI✓IS✓S g✓gc✓cc✓c [ _✓o_✓p_✓t_✓i_✓o_✓n | _✓f_✓i_✓l_✓e_✓n_✓a_✓m_✓e ]... g✓g+✓++✓+ [ _✓o_✓p_✓t_✓i_✓o_✓n | _✓f_✓i_✓l_✓e_✓n_✓a_✓m_✓e ]... W✓WA✓AR✓RN✓NI✓IN✓NG✓G The information in this man page is an extract from the full documentation of the GNU C compiler, and is limited to the meaning of the options. This man page is not kept up to date except when volun- teers want to maintain it. If you find a discrepancy between the man page and the software, please check the Info file, which is the authoritative documentation. If we find that the things in this man page that are out of date cause significant confusion or complaints, we will stop distributing the man page. The alternative, updating the man page when we update the Info file, is impossible because the rest of the work of maintaining GNU CC leaves us no time for that. The GNU project regards man pages as obsolete and should not let them take time away from other things. For complete and current documentation, refer to the Info file `g✓gc✓cc✓c' or the manual _✓U_✓s_✓i_✓n_✓g _✓a_✓n_✓d _✓P_✓o_✓r_✓t_✓i_✓n_✓g _✓G_✓N_✓U _✓C_✓C _✓(_✓f_✓o_✓r _✓v_✓e_✓r_✓s_✓i_✓o_✓n _✓2_✓._✓0_✓). Both are made from the Texinfo source file g✓gc✓cc✓c.✓.t✓te✓ex✓xi✓in✓nf✓fo✓o. D✓DE✓ES✓SC✓CR✓RI✓IP✓PT✓TI✓IO✓ON✓N The C and C++ compilers are integrated. Both process input files through one or more of four stages: prepro- cessing, compilation, assembly, and linking. Source file- name suffixes identify the source language, but which name you use for the compiler governs default assumptions: g✓gc✓cc✓c assumes preprocessed (.✓.i✓i) files are C and assumes C style linking. g✓g+✓++✓+ assumes preprocessed (.✓.i✓i) files are C++ and assumes C++ style linking. Suffixes of source file names indicate the language and kind of processing to be done: .✓.c✓c C source; preprocess, compile, assemble .✓.C✓C C++ source; preprocess, compile, assemble .✓.c✓cc✓c C++ source; preprocess, compile, assemble .✓.c✓cx✓xx✓x C++ source; preprocess, compile, assemble .✓.m✓m Objective-C source; preprocess, compile, assemble .✓.i✓i preprocessed C; compile, assemble .✓.i✓ii✓i preprocessed C++; compile, assemble GNU Tools 1993/10/13 1 GCC(1) GNU Tools GCC(1) .✓.s✓s Assembler source; assemble .✓.S✓S Assembler source; preprocess, assemble .✓.h✓h Preprocessor file; not usually named on command line Files with other suffixes are passed to the linker. Com- mon cases include: .✓.o✓o Object file .✓.a✓a Archive file Linking is always the last stage unless you use one of the -✓-c✓c, -✓-S✓S, or -✓-E✓E options to avoid it (or unless compilation errors stop the whole process). For the link stage, all .✓.o✓o files corresponding to source files, -✓-l✓l libraries, unrecognized filenames (including named .✓.o✓o object files and .✓.a✓a archives) are passed to the linker in command-line order. O✓OP✓PT✓TI✓IO✓ON✓NS✓S Options must be separate: `-✓-d✓dr✓r' is quite different from `-✓-d✓d -✓-r✓r '. Most `-✓-f✓f' and `-✓-W✓W' options have two contrary forms: -✓-f✓f_✓n_✓a_✓m_✓e and -✓-f✓fn✓no✓o-✓-_✓n_✓a_✓m_✓e (or -✓-W✓W_✓n_✓a_✓m_✓e and -✓-W✓Wn✓no✓o-✓-_✓n_✓a_✓m_✓e). Only the non- default forms are shown here. Here is a summary of all the options, grouped by type. Explanations are in the following sections. O✓Ov✓ve✓er✓ra✓al✓ll✓l O✓Op✓pt✓ti✓io✓on✓ns✓s -c -S -E -o _✓f_✓i_✓l_✓e -pipe -v -x _✓l_✓a_✓n_✓g_✓u_✓a_✓g_✓e L✓La✓an✓ng✓gu✓ua✓ag✓ge✓e O✓Op✓pt✓ti✓io✓on✓ns✓s -ansi -fall-virtual -fcond-mismatch -fdollars-in-identifiers -fenum-int-equiv -fexternal-templates -fno-asm -fno-builtin -fno-strict-prototype -fsigned-bitfields -fsigned-char -fthis-is-variable -funsigned-bitfields -funsigned-char -fwritable-strings -traditional -traditional-cpp -trigraphs W✓Wa✓ar✓rn✓ni✓in✓ng✓g O✓Op✓pt✓ti✓io✓on✓ns✓s -fsyntax-only -pedantic -pedantic-errors -w -W -Wall -Waggregate-return -Wcast-align -Wcast-qual -Wchar-subscript -Wcomment -Wconversion -Wenum-clash -Werror -Wformat -Wid-clash-_✓l_✓e_✓n -Wimplicit -Winline -Wmissing-prototypes -Wmissing-declarations -Wnested-externs -Wno-import -Wparentheses -Wpointer-arith -Wredundant-decls -Wreturn-type -Wshadow -Wstrict-prototypes -Wswitch -Wtemplate-debugging -Wtraditional -Wtrigraphs -Wuninitialized -Wunused -Wwrite-strings GNU Tools 1993/10/13 2 GCC(1) GNU Tools GCC(1) D✓De✓eb✓bu✓ug✓gg✓gi✓in✓ng✓g O✓Op✓pt✓ti✓io✓on✓ns✓s -a -d_✓l_✓e_✓t_✓t_✓e_✓r_✓s -fpretend-float -g -g_✓l_✓e_✓v_✓e_✓l -gcoff -gxcoff -gxcoff+ -gdwarf -gdwarf+ -gstabs -gstabs+ -ggdb -p -pg -save-temps -print-file-name=_✓l_✓i_✓b_✓r_✓a_✓r_✓y -print-libgcc-file-name -print-prog-name=_✓p_✓r_✓o_✓g_✓r_✓a_✓m O✓Op✓pt✓ti✓im✓mi✓iz✓za✓at✓ti✓io✓on✓n O✓Op✓pt✓ti✓io✓on✓ns✓s -fcaller-saves -fcse-follow-jumps -fcse-skip-blocks -fdelayed-branch -felide-constructors -fexpensive-optimizations -ffast-math -ffloat-store -fforce-addr -fforce-mem -finline-functions -fkeep-inline-functions -fmemoize-lookups -fno-default-inline -fno-defer-pop -fno-function-cse -fno-inline -fno-peephole -fomit-frame-pointer -frerun-cse-after-loop -fschedule-insns -fschedule-insns2 -fstrength-reduce -fthread-jumps -funroll-all-loops -funroll-loops -O -O2 P✓Pr✓re✓ep✓pr✓ro✓oc✓ce✓es✓ss✓so✓or✓r O✓Op✓pt✓ti✓io✓on✓ns✓s -A_✓a_✓s_✓s_✓e_✓r_✓t_✓i_✓o_✓n -C -dD -dM -dN -D_✓m_✓a_✓c_✓r_✓o[=_✓d_✓e_✓f_✓n] -E -H -idirafter _✓d_✓i_✓r -include _✓f_✓i_✓l_✓e -imacros _✓f_✓i_✓l_✓e -iprefix _✓f_✓i_✓l_✓e -iwithprefix _✓d_✓i_✓r -M -MD -MM -MMD -nostdinc -P -U_✓m_✓a_✓c_✓r_✓o -undef A✓As✓ss✓se✓em✓mb✓bl✓le✓er✓r O✓Op✓pt✓ti✓io✓on✓n -Wa,_✓o_✓p_✓t_✓i_✓o_✓n L✓Li✓in✓nk✓ke✓er✓r O✓Op✓pt✓ti✓io✓on✓ns✓s -l_✓l_✓i_✓b_✓r_✓a_✓r_✓y -nostartfiles -nostdlib -static -shared -symbolic -Xlinker _✓o_✓p_✓t_✓i_✓o_✓n -Wl,_✓o_✓p_✓t_✓i_✓o_✓n -u _✓s_✓y_✓m_✓b_✓o_✓l D✓Di✓ir✓re✓ec✓ct✓to✓or✓ry✓y O✓Op✓pt✓ti✓io✓on✓ns✓s -B_✓p_✓r_✓e_✓f_✓i_✓x -I_✓d_✓i_✓r -I- -L_✓d_✓i_✓r T✓Ta✓ar✓rg✓ge✓et✓t O✓Op✓pt✓ti✓io✓on✓ns✓s -b _✓m_✓a_✓c_✓h_✓i_✓n_✓e -V _✓v_✓e_✓r_✓s_✓i_✓o_✓n C✓Co✓on✓nf✓fi✓ig✓gu✓ur✓ra✓at✓ti✓io✓on✓n D✓De✓ep✓pe✓en✓nd✓de✓en✓nt✓t O✓Op✓pt✓ti✓io✓on✓ns✓s _✓M_✓6_✓8_✓0_✓x_✓0 _✓O_✓p_✓t_✓i_✓o_✓n_✓s -m68000 -m68020 -m68020-40 -m68030 -m68040 -m68881 -mbitfield -mc68000 -mc68020 -mfpa -mnobitfield -mrtd -mshort -msoft-float _✓V_✓A_✓X _✓O_✓p_✓t_✓i_✓o_✓n_✓s -mg -mgnu -munix _✓S_✓P_✓A_✓R_✓C _✓O_✓p_✓t_✓i_✓o_✓n_✓s -mepilogue -mfpu -mhard-float -mno-fpu -mno-epilogue -msoft-float -msparclite -mv8 -msupersparc -mcypress _✓C_✓o_✓n_✓v_✓e_✓x _✓O_✓p_✓t_✓i_✓o_✓n_✓s -margcount -mc1 -mc2 -mnoargcount GNU Tools 1993/10/13 3 GCC(1) GNU Tools GCC(1) _✓A_✓M_✓D_✓2_✓9_✓K _✓O_✓p_✓t_✓i_✓o_✓n_✓s -m29000 -m29050 -mbw -mdw -mkernel-registers -mlarge -mnbw -mnodw -msmall -mstack-check -muser-registers _✓M_✓8_✓8_✓K _✓O_✓p_✓t_✓i_✓o_✓n_✓s -m88000 -m88100 -m88110 -mbig-pic -mcheck-zero-division -mhandle-large-shift -midentify-revision -mno-check-zero-division -mno-ocs-debug-info -mno-ocs-frame-position -mno-optimize-arg-area -mno-seriazlize-volatile -mno-underscores -mocs-debug-info -mocs-frame-position -moptimize-arg-area -mserialize-volatile -mshort-data-_✓n_✓u_✓m -msvr3 -msvr4 -mtrap-large-shift -muse-div-instruction -mversion-03.00 -mwarn-passed-structs _✓R_✓S_✓6_✓0_✓0_✓0 _✓O_✓p_✓t_✓i_✓o_✓n_✓s -mfp-in-toc -mno-fop-in-toc _✓R_✓T _✓O_✓p_✓t_✓i_✓o_✓n_✓s -mcall-lib-mul -mfp-arg-in-fpregs -mfp-arg-in-gregs -mfull-fp-blocks -mhc-struct-return -min-line-mul -mminimum-fp-blocks -mnohc-struct-return _✓M_✓I_✓P_✓S _✓O_✓p_✓t_✓i_✓o_✓n_✓s -mcpu=_✓c_✓p_✓u _✓t_✓y_✓p_✓e -mips2 -mips3 -mint64 -mlong64 -mlonglong128 -mmips-as -mgas -mrnames -mno-rnames -mgpopt -mno-gpopt -mstats -mno-stats -mmemcpy -mno-memcpy -mno-mips-tfile -mmips-tfile -msoft-float -mhard-float -mabicalls -mno-abicalls -mhalf-pic -mno-half-pic -G _✓n_✓u_✓m -nocpp _✓i_✓3_✓8_✓6 _✓O_✓p_✓t_✓i_✓o_✓n_✓s -m486 -mno-486 -msoft-float -mno-fp-ret-in-387 _✓H_✓P_✓P_✓A _✓O_✓p_✓t_✓i_✓o_✓n_✓s -mpa-risc-1-0 -mpa-risc-1-1 -mkernel -mshared-libs -mno-shared-libs -mlong-calls -mdisable-fpregs -mdisable-indexing -mtrailing-colon _✓i_✓9_✓6_✓0 _✓O_✓p_✓t_✓i_✓o_✓n_✓s -m_✓c_✓p_✓u_✓-_✓t_✓y_✓p_✓e -mnumerics -msoft-float -mleaf-procedures -mno-leaf-procedures -mtail-call -mno-tail-call -mcomplex-addr -mno-complex-addr -mcode-align -mno-code-align -mic-compat -mic2.0-compat -mic3.0-compat -masm-compat -mintel-asm -mstrict-align -mno-strict-align -mold-align -mno-old-align _✓D_✓E_✓C _✓A_✓l_✓p_✓h_✓a _✓O_✓p_✓t_✓i_✓o_✓n_✓s -mfp-regs -mno-fp-regs -mno-soft-float -msoft-float _✓S_✓y_✓s_✓t_✓e_✓m _✓V _✓O_✓p_✓t_✓i_✓o_✓n_✓s GNU Tools 1993/10/13 4 GCC(1) GNU Tools GCC(1) -G -Qy -Qn -YP,_✓p_✓a_✓t_✓h_✓s -Ym,_✓d_✓i_✓r C✓Co✓od✓de✓e G✓Ge✓en✓ne✓er✓ra✓at✓ti✓io✓on✓n O✓Op✓pt✓ti✓io✓on✓ns✓s -fcall-saved-_✓r_✓e_✓g -fcall-used-_✓r_✓e_✓g -ffixed-_✓r_✓e_✓g -finhibit-size-directive -fnonnull-objects -fno-common -fno-ident -fno-gnu-linker -fpcc-struct-return -fpic -fPIC -freg-struct-returno -fshared-data -fshort-enums -fshort-double -fvolatile -fvolatile-global -fverbose-asm O✓OV✓VE✓ER✓RA✓AL✓LL✓L O✓OP✓PT✓TI✓IO✓ON✓NS✓S -✓-x✓x _✓l_✓a_✓n_✓g_✓u_✓a_✓g_✓e Specify explicitly the _✓l_✓a_✓n_✓g_✓u_✓a_✓g_✓e for the following input files (rather than choosing a default based on the file name suffix) . This option applies to all following input files until the next `-✓-x✓x' op- tion. Possible values of _✓l_✓a_✓n_✓g_✓u_✓a_✓g_✓e are `c✓c', `o✓ob✓bj✓je✓ec✓ct✓ti✓iv✓ve✓e-✓-c✓c', `c✓c-✓-h✓he✓ea✓ad✓de✓er✓r', `c✓c+✓++✓+', `c✓cp✓pp✓p-✓-o✓ou✓ut✓tp✓pu✓ut✓t', `a✓as✓ss✓se✓em✓mb✓bl✓le✓er✓r', and `a✓as✓ss✓se✓em✓mb✓bl✓le✓er✓r-✓-w✓wi✓it✓th✓h-✓-c✓cp✓pp✓p'. -✓-x✓x n✓no✓on✓ne✓e Turn off any specification of a language, so that subsequent files are handled according to their file name suffixes (as they are if `-✓-x✓x' has not been used at all). If you want only some of the four stages (preprocess, com- pile, assemble, link), you can use `-✓-x✓x' (or filename suf- fixes) to tell g✓gc✓cc✓c where to start, and one of the options `-✓-c✓c', `-✓-S✓S', or `-✓-E✓E' to say where g✓gc✓cc✓c is to stop. Note that some combinations (for example, `-✓-x✓x c✓cp✓pp✓p-✓-o✓ou✓ut✓tp✓pu✓ut✓t -✓-E✓E') instruct g✓gc✓cc✓c to do nothing at all. -✓-c✓c Compile or assemble the source files, but do not link. The compiler output is an object file corre- sponding to each source file. By default, GCC makes the object file name for a source file by replacing the suffix `.✓.c✓c', `.✓.i✓i', `.✓.s✓s', etc., with `.✓.o✓o'. Use -✓-o✓o to select another name. GCC ignores any unrecognized input files (those that do not require compilation or assembly) with the -✓-c✓c option. -✓-S✓S Stop after the stage of compilation proper; do not assemble. The output is an assembler code file for each non-assembler input file specified. By default, GCC makes the assembler file name for a source file by replacing the suffix `.✓.c✓c', `.✓.i✓i', etc., with `.✓.s✓s'. Use -✓-o✓o to select another name. GNU Tools 1993/10/13 5 GCC(1) GNU Tools GCC(1) GCC ignores any input files that don't require com- pilation. -✓-E✓E Stop after the preprocessing stage; do not run the compiler proper. The output is preprocessed source code, which is sent to the standard output. GCC ignores input files which don't require prepro- cessing. -✓-o✓o _✓f_✓i_✓l_✓e Place output in file _✓f_✓i_✓l_✓e. This applies regardless to whatever sort of output GCC is producing, whether it be an executable file, an object file, an assembler file or preprocessed C code. Since only one output file can be specified, it does not make sense to use `-✓-o✓o' when compiling more than one input file, unless you are producing an executable file as output. If you do not specify `-✓-o✓o', the default is to put an executable file in `a✓a.✓.o✓ou✓ut✓t', the object file for `_✓s_✓o_✓u_✓r_✓c_✓e.✓._✓s_✓u_✓f_✓f_✓i_✓x' in `_✓s_✓o_✓u_✓r_✓c_✓e.✓.o✓o', its assembler file in `_✓s_✓o_✓u_✓r_✓c_✓e.✓.s✓s', and all preprocessed C source on standard output. -✓-v✓v Print (on standard error output) the commands exe- cuted to run the stages of compilation. Also print the version number of the compiler driver program and of the preprocessor and the compiler proper. -✓-p✓pi✓ip✓pe✓e Use pipes rather than temporary files for communi- cation between the various stages of compilation. This fails to work on some systems where the assem- bler cannot read from a pipe; but the GNU assembler has no trouble. L✓LA✓AN✓NG✓GU✓UA✓AG✓GE✓E O✓OP✓PT✓TI✓IO✓ON✓NS✓S The following options control the dialect of C that the compiler accepts: -✓-a✓an✓ns✓si✓i Support all ANSI standard C programs. This turns off certain features of GNU C that are incompatible with ANSI C, such as the a✓as✓sm✓m, i✓in✓nl✓li✓in✓ne✓e and t✓ty✓yp✓pe✓eo✓of✓f keywords, and predefined macros such as u✓un✓ni✓ix✓x and v✓va✓ax✓x that identify the type of system you are using. It also enables the undesirable and rarely used ANSI trigraph feature, and disallows `$✓$' as part of identifiers. The alternate keywords _✓__✓_a✓as✓sm✓m_✓__✓_, _✓__✓_e✓ex✓xt✓te✓en✓ns✓si✓io✓on✓n_✓__✓_, GNU Tools 1993/10/13 6 GCC(1) GNU Tools GCC(1) _✓__✓_i✓in✓nl✓li✓in✓ne✓e_✓__✓_ and _✓__✓_t✓ty✓yp✓pe✓eo✓of✓f_✓__✓_ continue to work despite `-✓-a✓an✓ns✓si✓i'. You would not want to use them in an ANSI C program, of course, but it is useful to put them in header files that might be included in compila- tions done with `-✓-a✓an✓ns✓si✓i'. Alternate predefined macros such as _✓__✓_u✓un✓ni✓ix✓x_✓__✓_ and _✓__✓_v✓va✓ax✓x_✓__✓_ are also avail- able, with or without `-✓-a✓an✓ns✓si✓i'. The `-✓-a✓an✓ns✓si✓i' option does not cause non-ANSI programs to be rejected gratuitously. For that, `-✓-p✓pe✓ed✓da✓an✓nt✓ti✓ic✓c' is required in addition to `-✓-a✓an✓ns✓si✓i'. The preprocessor predefines a macro _✓__✓_S✓ST✓TR✓RI✓IC✓CT✓T_✓_A✓AN✓NS✓SI✓I_✓__✓_ when you use the `-✓-a✓an✓ns✓si✓i' option. Some header files may notice this macro and refrain from declaring certain functions or defining certain macros that the ANSI standard doesn't call for; this is to avoid interfering with any programs that might use these names for other things. -✓-f✓fn✓no✓o-✓-a✓as✓sm✓m Do not recognize a✓as✓sm✓m, i✓in✓nl✓li✓in✓ne✓e or t✓ty✓yp✓pe✓eo✓of✓f as a key- word. These words may then be used as identifiers. You can use _✓__✓_a✓as✓sm✓m_✓__✓_, _✓__✓_i✓in✓nl✓li✓in✓ne✓e_✓__✓_ and _✓__✓_t✓ty✓yp✓pe✓eo✓of✓f_✓__✓_ in- stead. `-✓-a✓an✓ns✓si✓i' implies `-✓-f✓fn✓no✓o-✓-a✓as✓sm✓m'. -✓-f✓fn✓no✓o-✓-b✓bu✓ui✓il✓lt✓ti✓in✓n Don't recognize built-in functions that do not be- gin with two leading underscores. Currently, the functions affected include _✓_e✓ex✓xi✓it✓t, a✓ab✓bo✓or✓rt✓t, a✓ab✓bs✓s, a✓al✓ll✓lo✓o-✓- c✓ca✓a, c✓co✓os✓s, e✓ex✓xi✓it✓t, f✓fa✓ab✓bs✓s, l✓la✓ab✓bs✓s, m✓me✓em✓mc✓cm✓mp✓p, m✓me✓em✓mc✓cp✓py✓y, s✓si✓in✓n, s✓sq✓qr✓rt✓t, s✓st✓tr✓rc✓cm✓mp✓p, s✓st✓tr✓rc✓cp✓py✓y, and s✓st✓tr✓rl✓le✓en✓n. The `-✓-a✓an✓ns✓si✓i' option prevents a✓al✓ll✓lo✓oc✓ca✓a and _✓_e✓ex✓xi✓it✓t from being builtin functions. -✓-f✓fn✓no✓o-✓-s✓st✓tr✓ri✓ic✓ct✓t-✓-p✓pr✓ro✓ot✓to✓ot✓ty✓yp✓pe✓e Treat a function declaration with no arguments, such as `i✓in✓nt✓t f✓fo✓oo✓o ();', as C would treat it--as say- ing nothing about the number of arguments or their types (C++ only). Normally, such a declaration in C++ means that the function f✓fo✓oo✓o takes no arguments. -✓-t✓tr✓ri✓ig✓gr✓ra✓ap✓ph✓hs✓s Support ANSI C trigraphs. The `-✓-a✓an✓ns✓si✓i' option im- plies `-✓-t✓tr✓ri✓ig✓gr✓ra✓ap✓ph✓hs✓s'. -✓-t✓tr✓ra✓ad✓di✓it✓ti✓io✓on✓na✓al✓l Attempt to support some aspects of traditional C compilers. For details, see the GNU C Manual; the duplicate list here has been deleted so that we won't get complaints when it is out of date. But one note about C++ programs only (not C). GNU Tools 1993/10/13 7 GCC(1) GNU Tools GCC(1) `-✓-t✓tr✓ra✓ad✓di✓it✓ti✓io✓on✓na✓al✓l' has one additional effect for C++: assignment to t✓th✓hi✓is✓s is permitted. This is the same as the effect of `-✓-f✓ft✓th✓hi✓is✓s-✓-i✓is✓s-✓-v✓va✓ar✓ri✓ia✓ab✓bl✓le✓e'. -✓-t✓tr✓ra✓ad✓di✓it✓ti✓io✓on✓na✓al✓l-✓-c✓cp✓pp✓p Attempt to support some aspects of traditional C preprocessors. This includes the items that specifically mention the preprocessor above, but none of the other effects of `-✓-t✓tr✓ra✓ad✓di✓it✓ti✓io✓on✓na✓al✓l'. -✓-f✓fd✓do✓ol✓ll✓la✓ar✓rs✓s-✓-i✓in✓n-✓-i✓id✓de✓en✓nt✓ti✓if✓fi✓ie✓er✓rs✓s Permit the use of `$✓$' in identifiers (C++ only). You can also use `-✓-f✓fn✓no✓o-✓-d✓do✓ol✓ll✓la✓ar✓rs✓s-✓-i✓in✓n-✓-i✓id✓de✓en✓nt✓ti✓if✓fi✓ie✓er✓rs✓s' to explicitly prohibit use of `$✓$'. (GNU C++ allows `$✓$' by default on some target systems but not oth- ers.) -✓-f✓fe✓en✓nu✓um✓m-✓-i✓in✓nt✓t-✓-e✓eq✓qu✓ui✓iv✓v Permit implicit conversion of i✓in✓nt✓t to enumeration types (C++ only). Normally GNU C++ allows conver- sion of e✓en✓nu✓um✓m to i✓in✓nt✓t, but not the other way around. -✓-f✓fe✓ex✓xt✓te✓er✓rn✓na✓al✓l-✓-t✓te✓em✓mp✓pl✓la✓at✓te✓es✓s Produce smaller code for template declarations, by generating only a single copy of each template function where it is defined (C++ only). To use this option successfully, you must also mark all files that use templates with either `#✓#p✓pr✓ra✓ag✓gm✓ma✓a i✓im✓mp✓pl✓le✓em✓me✓en✓nt✓ta✓at✓ti✓io✓on✓n' (the definition) or `#✓#p✓pr✓ra✓ag✓gm✓ma✓a i✓in✓nt✓te✓er✓rf✓fa✓ac✓ce✓e' (declarations). When your code is compiled with `-✓-f✓fe✓ex✓xt✓te✓er✓rn✓na✓al✓l-✓-t✓te✓em✓mp✓pl✓la✓at✓te✓es✓s', all template instantiations are external. You must arrange for all necessary instantiations to appear in the implementation file; you can do this with a t✓ty✓yp✓pe✓ed✓de✓ef✓f that refer- ences each instantiation needed. Conversely, when you compile using the default option `-✓-f✓fn✓no✓o-✓-e✓ex✓xt✓te✓er✓rn✓na✓al✓l-✓-t✓te✓em✓mp✓pl✓la✓at✓te✓es✓s', all template instantia- tions are explicitly internal. -✓-f✓fa✓al✓ll✓l-✓-v✓vi✓ir✓rt✓tu✓ua✓al✓l Treat all possible member functions as virtual, im- plicitly. All member functions (except for con- structor functions and n✓ne✓ew✓w or d✓de✓el✓le✓et✓te✓e member opera- tors) are treated as virtual functions of the class where they appear. This does not mean that all calls to these member functions will be made through the internal table of virtual functions. Under some circumstances, the compiler can determine that a call to a given virtual function can be made directly; in these cases the calls are direct in any case. GNU Tools 1993/10/13 8 GCC(1) GNU Tools GCC(1) -✓-f✓fc✓co✓on✓nd✓d-✓-m✓mi✓is✓sm✓ma✓at✓tc✓ch✓h Allow conditional expressions with mismatched types in the second and third arguments. The value of such an expression is void. -✓-f✓ft✓th✓hi✓is✓s-✓-i✓is✓s-✓-v✓va✓ar✓ri✓ia✓ab✓bl✓le✓e Permit assignment to t✓th✓hi✓is✓s (C++ only). The incorpo- ration of user-defined free store management into C++ has made assignment to `t✓th✓hi✓is✓s' an anachronism. Therefore, by default it is invalid to assign to t✓th✓hi✓is✓s within a class member function. However, for backwards compatibility, you can make it valid with `-✓-f✓ft✓th✓hi✓is✓s-✓-i✓is✓s-✓-v✓va✓ar✓ri✓ia✓ab✓bl✓le✓e'. -✓-f✓fu✓un✓ns✓si✓ig✓gn✓ne✓ed✓d-✓-c✓ch✓ha✓ar✓r Let the type c✓ch✓ha✓ar✓r be unsigned, like u✓un✓ns✓si✓ig✓gn✓ne✓ed✓d c✓ch✓ha✓ar✓r. Each kind of machine has a default for what c✓ch✓ha✓ar✓r should be. It is either like u✓un✓ns✓si✓ig✓gn✓ne✓ed✓d c✓ch✓ha✓ar✓r by de- fault or like s✓si✓ig✓gn✓ne✓ed✓d c✓ch✓ha✓ar✓r by default. Ideally, a portable program should always use s✓si✓ig✓gn✓ne✓ed✓d c✓ch✓ha✓ar✓r or u✓un✓ns✓si✓ig✓gn✓ne✓ed✓d c✓ch✓ha✓ar✓r when it depends on the signedness of an object. But many programs have been written to use plain c✓ch✓ha✓ar✓r and expect it to be signed, or expect it to be unsigned, depending on the machines they were written for. This option, and its inverse, let you make such a program work with the opposite default. The type c✓ch✓ha✓ar✓r is always a distinct type from each of s✓si✓ig✓gn✓ne✓ed✓d c✓ch✓ha✓ar✓r and u✓un✓ns✓si✓ig✓gn✓ne✓ed✓d c✓ch✓ha✓ar✓r, even though its behavior is always just like one of those two. -✓-f✓fs✓si✓ig✓gn✓ne✓ed✓d-✓-c✓ch✓ha✓ar✓r Let the type c✓ch✓ha✓ar✓r be signed, like s✓si✓ig✓gn✓ne✓ed✓d c✓ch✓ha✓ar✓r. Note that this is equivalent to `-✓-f✓fn✓no✓o-✓-u✓un✓ns✓si✓ig✓gn✓ne✓ed✓d-✓-c✓ch✓ha✓ar✓r', which is the negative form of `-✓-f✓fu✓un✓ns✓si✓ig✓gn✓ne✓ed✓d-✓-c✓ch✓ha✓ar✓r'. Likewise, `-✓-f✓fn✓no✓o-✓-s✓si✓ig✓gn✓ne✓ed✓d-✓-c✓ch✓ha✓ar✓r' is equivalent to `-✓-f✓fu✓un✓ns✓si✓ig✓gn✓ne✓ed✓d-✓-c✓ch✓ha✓ar✓r'. -✓-f✓fs✓si✓ig✓gn✓ne✓ed✓d-✓-b✓bi✓it✓tf✓fi✓ie✓el✓ld✓ds✓s -✓-f✓fu✓un✓ns✓si✓ig✓gn✓ne✓ed✓d-✓-b✓bi✓it✓tf✓fi✓ie✓el✓ld✓ds✓s -✓-f✓fn✓no✓o-✓-s✓si✓ig✓gn✓ne✓ed✓d-✓-b✓bi✓it✓tf✓fi✓ie✓el✓ld✓ds✓s -✓-f✓fn✓no✓o-✓-u✓un✓ns✓si✓ig✓gn✓ne✓ed✓d-✓-b✓bi✓it✓tf✓fi✓ie✓el✓ld✓ds✓s These options control whether a bitfield is signed or unsigned, when declared with no explicit `s✓si✓ig✓gn✓ne✓ed✓d' or `u✓un✓ns✓si✓ig✓gn✓ne✓ed✓d' qualifier. By default, such a bitfield is signed, because this is consistent: the basic integer types such as i✓in✓nt✓t are signed GNU Tools 1993/10/13 9 GCC(1) GNU Tools GCC(1) types. However, when you specify `-✓-t✓tr✓ra✓ad✓di✓it✓ti✓io✓on✓na✓al✓l', bitfields are all unsigned no matter what. -✓-f✓fw✓wr✓ri✓it✓ta✓ab✓bl✓le✓e-✓-s✓st✓tr✓ri✓in✓ng✓gs✓s Store string constants in the writable data segment and don't uniquize them. This is for compatibility with old programs which assume they can write into string constants. `-✓-t✓tr✓ra✓ad✓di✓it✓ti✓io✓on✓na✓al✓l' also has this ef- fect. Writing into string constants is a very bad idea; "constants" should be constant. P✓PR✓RE✓EP✓PR✓RO✓OC✓CE✓ES✓SS✓SO✓OR✓R O✓OP✓PT✓TI✓IO✓ON✓NS✓S These options control the C preprocessor, which is run on each C source file before actual compilation. If you use the `-✓-E✓E' option, GCC does nothing except pre- processing. Some of these options make sense only togeth- er with `-✓-E✓E' because they cause the preprocessor output to be unsuitable for actual compilation. -✓-i✓in✓nc✓cl✓lu✓ud✓de✓e _✓f_✓i_✓l_✓e Process _✓f_✓i_✓l_✓e as input before processing the regular input file. In effect, the contents of _✓f_✓i_✓l_✓e are compiled first. Any `-✓-D✓D' and `-✓-U✓U' options on the command line are always processed before `-✓-i✓in✓nc✓cl✓lu✓ud✓de✓e _✓f_✓i_✓l_✓e', regardless of the order in which they are written. All the `-✓-i✓in✓nc✓cl✓lu✓ud✓de✓e' and `-✓-i✓im✓ma✓ac✓cr✓ro✓os✓s' options are processed in the order in which they are writ- ten. -✓-i✓im✓ma✓ac✓cr✓ro✓os✓s _✓f_✓i_✓l_✓e Process _✓f_✓i_✓l_✓e as input, discarding the resulting output, before processing the regular input file. Because the output generated from _✓f_✓i_✓l_✓e is discard- ed, the only effect of `-✓-i✓im✓ma✓ac✓cr✓ro✓os✓s _✓f_✓i_✓l_✓e' is to make the macros defined in _✓f_✓i_✓l_✓e available for use in the main input. The preprocessor evaluates any `-✓-D✓D' and `-✓-U✓U' options on the command line before pro- cessing `-✓-i✓im✓ma✓ac✓cr✓ro✓os✓s_✓f_✓i_✓l_✓e', regardless of the order in which they are written. All the `-✓-i✓in✓nc✓cl✓lu✓ud✓de✓e' and `-✓-i✓im✓ma✓ac✓cr✓ro✓os✓s' options are processed in the order in which they are written. -✓-i✓id✓di✓ir✓ra✓af✓ft✓te✓er✓r _✓d_✓i_✓r Add the directory _✓d_✓i_✓r to the second include path. The directories on the second include path are searched when a header file is not found in any of the directories in the main include path (the one that `-✓-I✓I' adds to). GNU Tools 1993/10/13 10 GCC(1) GNU Tools GCC(1) -✓-i✓ip✓pr✓re✓ef✓fi✓ix✓x _✓p_✓r_✓e_✓f_✓i_✓x Specify _✓p_✓r_✓e_✓f_✓i_✓x as the prefix for subsequent `-✓-i✓iw✓wi✓it✓th✓hp✓pr✓re✓ef✓fi✓ix✓x' options. -✓-i✓iw✓wi✓it✓th✓hp✓pr✓re✓ef✓fi✓ix✓x _✓d_✓i_✓r Add a directory to the second include path. The directory's name is made by concatenating _✓p_✓r_✓e_✓f_✓i_✓x and _✓d_✓i_✓r, where _✓p_✓r_✓e_✓f_✓i_✓x was specified previously with `-✓-i✓ip✓pr✓re✓ef✓fi✓ix✓x'. -✓-n✓no✓os✓st✓td✓di✓in✓nc✓c Do not search the standard system directories for header files. Only the directories you have speci- fied with `-✓-I✓I' options (and the current directory, if appropriate) are searched. By using both `-✓-n✓no✓os✓st✓td✓di✓in✓nc✓c' and `-✓-I✓I-✓-', you can limit the include-file search file to only those directo- ries you specify explicitly. -✓-n✓no✓os✓st✓td✓di✓in✓nc✓c+✓++✓+ Do not search for header files in the C++-specific standard directories, but do still search the other standard directories. (This option is used when building `l✓li✓ib✓bg✓g+✓++✓+'.) -✓-u✓un✓nd✓de✓ef✓f Do not predefine any nonstandard macros. (Includ- ing architecture flags). -✓-E✓E Run only the C preprocessor. Preprocess all the C source files specified and output the results to standard output or to the specified output file. -✓-C✓C Tell the preprocessor not to discard comments. Used with the `-✓-E✓E' option. -✓-P✓P Tell the preprocessor not to generate `#✓#l✓li✓in✓ne✓e' com- mands. Used with the `-✓-E✓E' option. -✓-M✓M [✓[ -✓-M✓MG✓G ]✓] Tell the preprocessor to output a rule suitable for m✓ma✓ak✓ke✓e describing the dependencies of each object file. For each source file, the preprocessor out- puts one m✓ma✓ak✓ke✓e-rule whose target is the object file name for that source file and whose dependencies are all the files `#✓#i✓in✓nc✓cl✓lu✓ud✓de✓e'd in it. This rule may be a single line or may be continued with `\✓\'-new- line if it is long. The list of rules is printed on standard output instead of the preprocessed C program. `-✓-M✓M' implies `-✓-E✓E'. `-✓-M✓MG✓G' says to treat missing header files as gener- GNU Tools 1993/10/13 11 GCC(1) GNU Tools GCC(1) ated files and assume they live in the same direc- tory as the source file. It must be specified in addition to `-✓-M✓M'. -✓-M✓MM✓M [✓[ -✓-M✓MG✓G ]✓] Like `-✓-M✓M' but the output mentions only the user header files included with `#✓#i✓in✓nc✓cl✓lu✓ud✓de✓e _✓f_✓i_✓l_✓e"'. Sys- tem header files included with `#✓#i✓in✓nc✓cl✓lu✓ud✓de✓e <✓<_✓f_✓i_✓l_✓e>' are omitted. -✓-M✓MD✓D Like `-✓-M✓M' but the dependency information is written to files with names made by replacing `.✓.o✓o' with `.✓.d✓d' at the end of the output file names. This is in addition to compiling the file as specified--`-✓-M✓MD✓D' does not inhibit ordinary compila- tion the way `-✓-M✓M' does. The Mach utility `m✓md✓d' can be used to merge the `.✓.d✓d' files into a single dependency file suitable for using with the `m✓ma✓ak✓ke✓e' command. -✓-M✓MM✓MD✓D Like `-✓-M✓MD✓D' except mention only user header files, not system header files. -✓-H✓H Print the name of each header file used, in addi- tion to other normal activities. -✓-A✓A_✓q_✓u_✓e_✓s_✓t_✓i_✓o_✓n(✓(_✓a_✓n_✓s_✓w_✓e_✓r)✓) Assert the answer _✓a_✓n_✓s_✓w_✓e_✓r for _✓q_✓u_✓e_✓s_✓t_✓i_✓o_✓n, in case it is tested with a preprocessor conditional such as `#✓#i✓if✓f #✓#_✓q_✓u_✓e_✓s_✓t_✓i_✓o_✓n(✓(_✓a_✓n_✓s_✓w_✓e_✓r)✓)'. `-✓-A✓A-✓-' disables the stan- dard assertions that normally describe the target machine. -✓-A✓A_✓q_✓u_✓e_✓s_✓t_✓i_✓o_✓n (_✓a_✓n_✓s_✓w_✓e_✓r) Assert the answer _✓a_✓n_✓s_✓w_✓e_✓r for _✓q_✓u_✓e_✓s_✓t_✓i_✓o_✓n, in case it is tested with a preprocessor conditional such as `#✓#i✓if✓f #_✓q_✓u_✓e_✓s_✓t_✓i_✓o_✓n(_✓a_✓n_✓s_✓w_✓e_✓r)'. `-✓-A✓A-✓-' disables the standard assertions that normally describe the target machine. -✓-D✓D_✓m_✓a_✓c_✓r_✓o Define macro _✓m_✓a_✓c_✓r_✓o with the string `1✓1' as its defi- nition. -✓-D✓D_✓m_✓a_✓c_✓r_✓o=✓=_✓d_✓e_✓f_✓n Define macro _✓m_✓a_✓c_✓r_✓o as _✓d_✓e_✓f_✓n. All instances of `-✓-D✓D' on the command line are processed before any `-✓-U✓U' options. -✓-U✓U_✓m_✓a_✓c_✓r_✓o Undefine macro _✓m_✓a_✓c_✓r_✓o. `-✓-U✓U' options are evaluated after all `-✓-D✓D' options, but before any `-✓-i✓in✓nc✓cl✓lu✓ud✓de✓e' and `-✓-i✓im✓ma✓ac✓cr✓ro✓os✓s' options. GNU Tools 1993/10/13 12 GCC(1) GNU Tools GCC(1) -✓-d✓dM✓M Tell the preprocessor to output only a list of the macro definitions that are in effect at the end of preprocessing. Used with the `-✓-E✓E' option. -✓-d✓dD✓D Tell the preprocessor to pass all macro definitions into the output, in their proper sequence in the rest of the output. -✓-d✓dN✓N Like `-✓-d✓dD✓D' except that the macro arguments and con- tents are omitted. Only `#✓#d✓de✓ef✓fi✓in✓ne✓e _✓n_✓a_✓m_✓e' is included in the output. A✓AS✓SS✓SE✓EM✓MB✓BL✓LE✓ER✓R O✓OP✓PT✓TI✓IO✓ON✓N -✓-W✓Wa✓a,✓,_✓o_✓p_✓t_✓i_✓o_✓n Pass _✓o_✓p_✓t_✓i_✓o_✓n as an option to the assembler. If _✓o_✓p_✓- _✓t_✓i_✓o_✓n contains commas, it is split into multiple op- tions at the commas. L✓LI✓IN✓NK✓KE✓ER✓R O✓OP✓PT✓TI✓IO✓ON✓NS✓S These options come into play when the compiler links ob- ject files into an executable output file. They are mean- ingless if the compiler is not doing a link step. _✓o_✓b_✓j_✓e_✓c_✓t_✓-_✓f_✓i_✓l_✓e_✓-_✓n_✓a_✓m_✓e A file name that does not end in a special recog- nized suffix is considered to name an object file or library. (Object files are distinguished from libraries by the linker according to the file con- tents.) If GCC does a link step, these object files are used as input to the linker. -✓-l✓l_✓l_✓i_✓b_✓r_✓a_✓r_✓y Use the library named _✓l_✓i_✓b_✓r_✓a_✓r_✓y when linking. The linker searches a standard list of directories for the library, which is actually a file named `l✓li✓ib✓b_✓l_✓i_✓b_✓r_✓a_✓r_✓y.a'. The linker then uses this file as if it had been specified precisely by name. The directories searched include several standard system directories plus any that you specify with `-✓-L✓L'. Normally the files found this way are library files--archive files whose members are object files. The linker handles an archive file by scan- ning through it for members which define symbols that have so far been referenced but not defined. However, if the linker finds an ordinary object file rather than a library, the object file is linked in the usual fashion. The only difference between using an `-✓-l✓l' option and specifying a file name is that `-✓-l✓l' surrounds _✓l_✓i_✓b_✓r_✓a_✓r_✓y with `l✓li✓ib✓b' and `.✓.a✓a' and searches several directories. GNU Tools 1993/10/13 13 GCC(1) GNU Tools GCC(1) -✓-l✓lo✓ob✓bj✓jc✓c You need this special case of the -✓-l✓l option in or- der to link an Objective C program. -✓-n✓no✓os✓st✓ta✓ar✓rt✓tf✓fi✓il✓le✓es✓s Do not use the standard system startup files when linking. The standard libraries are used normally. -✓-n✓no✓os✓st✓td✓dl✓li✓ib✓b Don't use the standard system libraries and startup files when linking. Only the files you specify will be passed to the linker. -✓-s✓st✓ta✓at✓ti✓ic✓c On systems that support dynamic linking, this pre- vents linking with the shared libraries. On other systems, this option has no effect. -✓-s✓sh✓ha✓ar✓re✓ed✓d Produce a shared object which can then be linked with other objects to form an executable. Only a few systems support this option. -✓-s✓sy✓ym✓mb✓bo✓ol✓li✓ic✓c Bind references to global symbols when building a shared object. Warn about any unresolved refer- ences (unless overridden by the link editor option `-✓-X✓Xl✓li✓in✓nk✓ke✓er✓r -✓-z✓z -✓-X✓Xl✓li✓in✓nk✓ke✓er✓r d✓de✓ef✓fs✓s'). Only a few systems support this option. -✓-X✓Xl✓li✓in✓nk✓ke✓er✓r _✓o_✓p_✓t_✓i_✓o_✓n Pass _✓o_✓p_✓t_✓i_✓o_✓n as an option to the linker. You can use this to supply system-specific linker options which GNU CC does not know how to recognize. If you want to pass an option that takes an argu- ment, you must use `-✓-X✓Xl✓li✓in✓nk✓ke✓er✓r' twice, once for the option and once for the argument. For example, to pass `-✓-a✓as✓ss✓se✓er✓rt✓t d✓de✓ef✓fi✓in✓ni✓it✓ti✓io✓on✓ns✓s', you must write `-✓-X✓Xl✓li✓in✓nk✓k-✓- e✓er✓r -✓-a✓as✓ss✓se✓er✓rt✓t -✓-X✓Xl✓li✓in✓nk✓ke✓er✓r d✓de✓ef✓fi✓in✓ni✓it✓ti✓io✓on✓ns✓s'. It does not work to write `-✓-X✓Xl✓li✓in✓nk✓ke✓er✓r "✓"-✓-a✓as✓ss✓se✓er✓rt✓t d✓de✓ef✓fi✓in✓ni✓it✓ti✓io✓on✓ns✓s"✓"', because this passes the entire string as a single argument, which is not what the linker expects. -✓-W✓Wl✓l,✓,_✓o_✓p_✓t_✓i_✓o_✓n Pass _✓o_✓p_✓t_✓i_✓o_✓n as an option to the linker. If _✓o_✓p_✓t_✓i_✓o_✓n contains commas, it is split into multiple options at the commas. -✓-u✓u _✓s_✓y_✓m_✓b_✓o_✓l Pretend the symbol _✓s_✓y_✓m_✓b_✓o_✓l is undefined, to force linking of library modules to define it. You can use `-✓-u✓u' multiple times with different symbols to force loading of additional library modules. GNU Tools 1993/10/13 14 GCC(1) GNU Tools GCC(1) D✓DI✓IR✓RE✓EC✓CT✓TO✓OR✓RY✓Y O✓OP✓PT✓TI✓IO✓ON✓NS✓S These options specify directories to search for header files, for libraries and for parts of the compiler: -✓-I✓I_✓d_✓i_✓r Append directory _✓d_✓i_✓r to the list of directories searched for include files. -✓-I✓I-✓- Any directories you specify with `-✓-I✓I' options be- fore the `-✓-I✓I-✓-' option are searched only for the case of `#✓#i✓in✓nc✓cl✓lu✓ud✓de✓e "✓"_✓f_✓i_✓l_✓e"✓"'; they are not searched for `#✓#i✓in✓nc✓cl✓lu✓ud✓de✓e <✓<_✓f_✓i_✓l_✓e>'. If additional directories are specified with `-✓-I✓I' options after the `-✓-I✓I-✓-', these directories are searched for all `#✓#i✓in✓nc✓cl✓lu✓ud✓de✓e' directives. (Ordinari- ly _✓a_✓l_✓l `-✓-I✓I' directories are used this way.) In addition, the `-✓-I✓I-✓-' option inhibits the use of the current directory (where the current input file came from) as the first search directory for `#✓#i✓in✓n-✓- c✓cl✓lu✓ud✓de✓e "✓"_✓f_✓i_✓l_✓e"✓"'. There is no way to override this effect of `-✓-I✓I-✓-'. With `-✓-I✓I.✓.' you can specify searching the directory which was current when the compiler was invoked. That is not exactly the same as what the preprocessor does by default, but it is often satisfactory. `-✓-I✓I-✓-' does not inhibit the use of the standard sys- tem directories for header files. Thus, `-✓-I✓I-✓-' and `-✓-n✓no✓os✓st✓td✓di✓in✓nc✓c' are independent. -✓-L✓L_✓d_✓i_✓r Add directory _✓d_✓i_✓r to the list of directories to be searched for `-✓-l✓l'. -✓-B✓B_✓p_✓r_✓e_✓f_✓i_✓x This option specifies where to find the executa- bles, libraries and data files of the compiler it- self. The compiler driver program runs one or more of the subprograms `c✓cp✓pp✓p', `c✓cc✓c1✓1' (or, for C++, `c✓cc✓c1✓1p✓pl✓lu✓us✓s'), `a✓as✓s' and `l✓ld✓d'. It tries _✓p_✓r_✓e_✓f_✓i_✓x as a prefix for each program it tries to run, both with and without `_✓m_✓a_✓c_✓h_✓i_✓n_✓e/✓/_✓v_✓e_✓r_✓s_✓i_✓o_✓n/✓/'. For each subprogram to be run, the compiler driver first tries the `-✓-B✓B' prefix, if any. If that name is not found, or if `-✓-B✓B' was not specified, the driver tries two standard prefixes, which are `/✓/u✓us✓sr✓r/✓/l✓li✓ib✓b/✓/g✓gc✓cc✓c/✓/' and `/✓/u✓us✓sr✓r/✓/l✓lo✓oc✓ca✓al✓l/✓/l✓li✓ib✓b/✓/g✓gc✓cc✓c-✓-l✓li✓ib✓b/✓/'. If neither of those results in a file name that is found, the compiler driver searches for the unmodi- fied program name, using the directories specified in your `P✓PA✓AT✓TH✓H' environment variable. GNU Tools 1993/10/13 15 GCC(1) GNU Tools GCC(1) The run-time support file `l✓li✓ib✓bg✓gc✓cc✓c.✓.a✓a' is also searched for using the `-✓-B✓B' prefix, if needed. If it is not found there, the two standard prefixes above are tried, and that is all. The file is left out of the link if it is not found by those means. Most of the time, on most machines, `l✓li✓ib✓bg✓gc✓cc✓c.✓.a✓a' is not actually necessary. You can get a similar result from the environment variable G✓GC✓CC✓C_✓_E✓EX✓XE✓EC✓C_✓_P✓PR✓RE✓EF✓FI✓IX✓X; if it is defined, its value is used as a prefix in the same way. If both the `-✓-B✓B' option and the G✓GC✓CC✓C_✓_E✓EX✓XE✓EC✓C_✓_P✓PR✓RE✓EF✓FI✓IX✓X variable are present, the `-✓-B✓B' option is used first and the environment variable value second. W✓WA✓AR✓RN✓NI✓IN✓NG✓G O✓OP✓PT✓TI✓IO✓ON✓NS✓S Warnings are diagnostic messages that report constructions which are not inherently erroneous but which are risky or suggest there may have been an error. These options control the amount and kinds of warnings produced by GNU CC: -✓-f✓fs✓sy✓yn✓nt✓ta✓ax✓x-✓-o✓on✓nl✓ly✓y Check the code for syntax errors, but don't emit any output. -✓-w✓w Inhibit all warning messages. -✓-W✓Wn✓no✓o-✓-i✓im✓mp✓po✓or✓rt✓t Inhibit warning messages about the use of #✓#i✓im✓mp✓po✓or✓rt✓t. -✓-p✓pe✓ed✓da✓an✓nt✓ti✓ic✓c Issue all the warnings demanded by strict ANSI standard C; reject all programs that use forbidden extensions. Valid ANSI standard C programs should compile prop- erly with or without this option (though a rare few will require `-✓-a✓an✓ns✓si✓i'). However, without this op- tion, certain GNU extensions and traditional C fea- tures are supported as well. With this option, they are rejected. There is no reason to _✓u_✓s_✓e this option; it exists only to satisfy pedants. `-✓-p✓pe✓ed✓da✓an✓nt✓ti✓ic✓c' does not cause warning messages for use of the alternate keywords whose names begin and end with `_✓__✓_'. Pedantic warnings are also disabled in the expression that follows _✓__✓_e✓ex✓xt✓te✓en✓ns✓si✓io✓on✓n_✓__✓_. Howev- er, only system header files should use these es- cape routes; application programs should avoid them. GNU Tools 1993/10/13 16 GCC(1) GNU Tools GCC(1) -✓-p✓pe✓ed✓da✓an✓nt✓ti✓ic✓c-✓-e✓er✓rr✓ro✓or✓rs✓s Like `-✓-p✓pe✓ed✓da✓an✓nt✓ti✓ic✓c', except that errors are produced rather than warnings. -✓-W✓W Print extra warning messages for these events: +✓o A nonvolatile automatic variable might be changed by a call to l✓lo✓on✓ng✓gj✓jm✓mp✓p. These warnings are possible only in optimizing compilation. The compiler sees only the calls to s✓se✓et✓tj✓jm✓mp✓p. It cannot know where l✓lo✓on✓ng✓gj✓jm✓mp✓p will be called; in fact, a signal handler could call it at any point in the code. As a result, you may get a warning even when there is in fact no problem because l✓lo✓on✓ng✓gj✓jm✓mp✓p cannot in fact be called at the place which would cause a problem. +✓o A function can return either with or without a val- ue. (Falling off the end of the function body is considered returning without a value.) For exam- ple, this function would evoke such a warning: foo (a) { if (a > 0) return a; } Spurious warnings can occur because GNU CC does not realize that certain functions (including a✓ab✓bo✓or✓rt✓t and l✓lo✓on✓ng✓gj✓jm✓mp✓p) will never return. +✓o An expression-statement contains no side effects. +✓o An unsigned value is compared against zero with `>✓>' or `<✓<=✓='. -✓-W✓Wi✓im✓mp✓pl✓li✓ic✓ci✓it✓t Warn whenever a function or parameter is implicitly declared. -✓-W✓Wr✓re✓et✓tu✓ur✓rn✓n-✓-t✓ty✓yp✓pe✓e Warn whenever a function is defined with a return- type that defaults to i✓in✓nt✓t. Also warn about any r✓re✓e-✓- t✓tu✓ur✓rn✓n statement with no return-value in a function whose return-type is not v✓vo✓oi✓id✓d. -✓-W✓Wu✓un✓nu✓us✓se✓ed✓d Warn whenever a local variable is unused aside from its declaration, whenever a function is declared static but never defined, and whenever a statement computes a result that is explicitly not used. GNU Tools 1993/10/13 17 GCC(1) GNU Tools GCC(1) -✓-W✓Ws✓sw✓wi✓it✓tc✓ch✓h Warn whenever a s✓sw✓wi✓it✓tc✓ch✓h statement has an index of enumeral type and lacks a c✓ca✓as✓se✓e for one or more of the named codes of that enumeration. (The presence of a d✓de✓ef✓fa✓au✓ul✓lt✓t label prevents this warning.) c✓ca✓as✓se✓e labels outside the enumeration range also provoke warnings when this option is used. -✓-W✓Wc✓co✓om✓mm✓me✓en✓nt✓t Warn whenever a comment-start sequence `/✓/*✓*' appears in a comment. -✓-W✓Wt✓tr✓ri✓ig✓gr✓ra✓ap✓ph✓hs✓s Warn if any trigraphs are encountered (assuming they are enabled). -✓-W✓Wf✓fo✓or✓rm✓ma✓at✓t Check calls to p✓pr✓ri✓in✓nt✓tf✓f and s✓sc✓ca✓an✓nf✓f, etc., to make sure that the arguments supplied have types appropriate to the format string specified. -✓-W✓Wc✓ch✓ha✓ar✓r-✓-s✓su✓ub✓bs✓sc✓cr✓ri✓ip✓pt✓ts✓s Warn if an array subscript has type c✓ch✓ha✓ar✓r. This is a common cause of error, as programmers often for- get that this type is signed on some machines. -✓-W✓Wu✓un✓ni✓in✓ni✓it✓ti✓ia✓al✓li✓iz✓ze✓ed✓d An automatic variable is used without first being initialized. These warnings are possible only in optimizing com- pilation, because they require data flow informa- tion that is computed only when optimizing. If you don't specify `-✓-O✓O', you simply won't get these warnings. These warnings occur only for variables that are candidates for register allocation. Therefore, they do not occur for a variable that is declared v✓vo✓ol✓la✓at✓ti✓il✓le✓e, or whose address is taken, or whose size is other than 1, 2, 4 or 8 bytes. Also, they do not occur for structures, unions or arrays, even when they are in registers. Note that there may be no warning about a variable that is used only to compute a value that itself is never used, because such computations may be delet- ed by data flow analysis before the warnings are printed. These warnings are made optional because GNU CC is not smart enough to see all the reasons why the code might be correct despite appearing to have an error. Here is one example of how this can happen: GNU Tools 1993/10/13 18 GCC(1) GNU Tools GCC(1) { int x; switch (y) { case 1: x = 1; break; case 2: x = 4; break; case 3: x = 5; } foo (x); } If the value of y✓y is always 1, 2 or 3, then x✓x is always initialized, but GNU CC doesn't know this. Here is another common case: { int save_y; if (change_y) save_y = y, y = new_y; ... if (change_y) y = save_y; } This has no bug because s✓sa✓av✓ve✓e_✓_y✓y is used only if it is set. Some spurious warnings can be avoided if you de- clare as v✓vo✓ol✓la✓at✓ti✓il✓le✓e all the functions you use that never return. -✓-W✓Wp✓pa✓ar✓re✓en✓nt✓th✓he✓es✓se✓es✓s Warn if parentheses are omitted in certain con- texts. -✓-W✓Wt✓te✓em✓mp✓pl✓la✓at✓te✓e-✓-d✓de✓eb✓bu✓ug✓gg✓gi✓in✓ng✓g When using templates in a C++ program, warn if de- bugging is not yet fully available (C++ only). -✓-W✓Wa✓al✓ll✓l All of the above `-✓-W✓W' options combined. These are all the options which pertain to usage that we rec- ommend avoiding and that we believe is easy to avoid, even in conjunction with macros. The remaining `-✓-W✓W.✓..✓..✓.' options are not implied by `-✓-W✓Wa✓al✓ll✓l' because they warn about constructions that we consider reasonable to use, on occasion, in clean programs. -✓-W✓Wt✓tr✓ra✓ad✓di✓it✓ti✓io✓on✓na✓al✓l Warn about certain constructs that behave differ- ently in traditional and ANSI C. +✓o Macro arguments occurring within string constants in the macro body. These would substitute the ar- GNU Tools 1993/10/13 19 GCC(1) GNU Tools GCC(1) gument in traditional C, but are part of the con- stant in ANSI C. +✓o A function declared external in one block and then used after the end of the block. +✓o A s✓sw✓wi✓it✓tc✓ch✓h statement has an operand of type l✓lo✓on✓ng✓g. -✓-W✓Ws✓sh✓ha✓ad✓do✓ow✓w Warn whenever a local variable shadows another lo- cal variable. -✓-W✓Wi✓id✓d-✓-c✓cl✓la✓as✓sh✓h-✓-_✓l_✓e_✓n Warn whenever two distinct identifiers match in the first _✓l_✓e_✓n characters. This may help you prepare a program that will compile with certain obsolete, brain-damaged compilers. -✓-W✓Wp✓po✓oi✓in✓nt✓te✓er✓r-✓-a✓ar✓ri✓it✓th✓h Warn about anything that depends on the "size of" a function type or of v✓vo✓oi✓id✓d. GNU C assigns these types a size of 1, for convenience in calculations with v✓vo✓oi✓id✓d *✓* pointers and pointers to functions. -✓-W✓Wc✓ca✓as✓st✓t-✓-q✓qu✓ua✓al✓l Warn whenever a pointer is cast so as to remove a type qualifier from the target type. For example, warn if a c✓co✓on✓ns✓st✓t c✓ch✓ha✓ar✓r *✓* is cast to an ordinary c✓ch✓ha✓ar✓r *✓*. -✓-W✓Wc✓ca✓as✓st✓t-✓-a✓al✓li✓ig✓gn✓n Warn whenever a pointer is cast such that the re- quired alignment of the target is increased. For example, warn if a c✓ch✓ha✓ar✓r *✓* is cast to an i✓in✓nt✓t *✓* on machines where integers can only be accessed at two- or four-byte boundaries. -✓-W✓Ww✓wr✓ri✓it✓te✓e-✓-s✓st✓tr✓ri✓in✓ng✓gs✓s Give string constants the type c✓co✓on✓ns✓st✓t c✓ch✓ha✓ar✓r[✓[_✓l_✓e_✓n_✓g_✓t_✓h]✓] so that copying the address of one into a non-c✓co✓on✓ns✓st✓t c✓ch✓ha✓ar✓r *✓* pointer will get a warning. These warnings will help you find at compile time code that can try to write into a string constant, but only if you have been very careful about using c✓co✓on✓ns✓st✓t in declarations and prototypes. Otherwise, it will just be a nuisance; this is why we did not make `-✓-W✓Wa✓al✓ll✓l' request these warnings. -✓-W✓Wc✓co✓on✓nv✓ve✓er✓rs✓si✓io✓on✓n Warn if a prototype causes a type conversion that is different from what would happen to the same ar- gument in the absence of a prototype. This in- cludes conversions of fixed point to floating and GNU Tools 1993/10/13 20 GCC(1) GNU Tools GCC(1) vice versa, and conversions changing the width or signedness of a fixed point argument except when the same as the default promotion. -✓-W✓Wa✓ag✓gg✓gr✓re✓eg✓ga✓at✓te✓e-✓-r✓re✓et✓tu✓ur✓rn✓n Warn if any functions that return structures or unions are defined or called. (In languages where you can return an array, this also elicits a warn- ing.) -✓-W✓Ws✓st✓tr✓ri✓ic✓ct✓t-✓-p✓pr✓ro✓ot✓to✓ot✓ty✓yp✓pe✓es✓s Warn if a function is declared or defined without specifying the argument types. (An old-style func- tion definition is permitted without a warning if preceded by a declaration which specifies the argu- ment types.) -✓-W✓Wm✓mi✓is✓ss✓si✓in✓ng✓g-✓-p✓pr✓ro✓ot✓to✓ot✓ty✓yp✓pe✓es✓s Warn if a global function is defined without a pre- vious prototype declaration. This warning is is- sued even if the definition itself provides a pro- totype. The aim is to detect global functions that fail to be declared in header files. -✓-W✓Wm✓mi✓is✓ss✓si✓in✓ng✓g-✓-d✓de✓ec✓cl✓la✓ar✓ra✓at✓ti✓io✓on✓ns✓s Warn if a global function is defined without a pre- vious declaration. Do so even if the definition itself provides a prototype. Use this option to detect global functions that are not declared in header files. -✓-W✓Wr✓re✓ed✓du✓un✓nd✓da✓an✓nt✓t-✓-d✓de✓ec✓cl✓ls✓s Warn if anything is declared more than once in the same scope, even in cases where multiple declara- tion is valid and changes nothing. -✓-W✓Wn✓ne✓es✓st✓te✓ed✓d-✓-e✓ex✓xt✓te✓er✓rn✓ns✓s Warn if an e✓ex✓xt✓te✓er✓rn✓n declaration is encountered within an function. -✓-W✓We✓en✓nu✓um✓m-✓-c✓cl✓la✓as✓sh✓h Warn about conversion between different enumeration types (C++ only). -✓-W✓Wo✓ov✓ve✓er✓rl✓lo✓oa✓ad✓de✓ed✓d-✓-v✓vi✓ir✓rt✓tu✓ua✓al✓l (C++ only.) In a derived class, the definitions of virtual functions must match the type signature of a virtual function declared in the base class. Use this option to request warnings when a derived class declares a function that may be an erroneous attempt to define a virtual function: that is, warn when a function with the same name as a virtual function in the base class, but with a type signa- ture that doesn't match any virtual functions from GNU Tools 1993/10/13 21 GCC(1) GNU Tools GCC(1) the base class. -✓-W✓Wi✓in✓nl✓li✓in✓ne✓e Warn if a function can not be inlined, and either it was declared as inline, or else the -✓-f✓fi✓in✓n-✓- l✓li✓in✓ne✓e-✓-f✓fu✓un✓nc✓ct✓ti✓io✓on✓ns✓s option was given. -✓-W✓We✓er✓rr✓ro✓or✓r Treat warnings as errors; abort compilation after any warning. D✓DE✓EB✓BU✓UG✓GG✓GI✓IN✓NG✓G O✓OP✓PT✓TI✓IO✓ON✓NS✓S GNU CC has various special options that are used for de- bugging either your program or GCC: -✓-g✓g Produce debugging information in the operating sys- tem's native format (stabs, COFF, XCOFF, or DWARF). GDB can work with this debugging information. On most systems that use stabs format, `-✓-g✓g' enables use of extra debugging information that only GDB can use; this extra information makes debugging work better in GDB but will probably make other de- buggers crash or refuse to read the program. If you want to control for certain whether to generate the extra information, use `-✓-g✓gs✓st✓ta✓ab✓bs✓s+✓+', `-✓-g✓gs✓st✓ta✓ab✓bs✓s', `-✓-g✓gx✓xc✓co✓of✓ff✓f+✓+', `-✓-g✓gx✓xc✓co✓of✓ff✓f', `-✓-g✓gd✓dw✓wa✓ar✓rf✓f+✓+', or `-✓-g✓gd✓dw✓wa✓ar✓rf✓f' (see below). Unlike most other C compilers, GNU CC allows you to use `-✓-g✓g' with `-✓-O✓O'. The shortcuts taken by opti- mized code may occasionally produce surprising re- sults: some variables you declared may not exist at all; flow of control may briefly move where you did not expect it; some statements may not be executed because they compute constant results or their val- ues were already at hand; some statements may exe- cute in different places because they were moved out of loops. Nevertheless it proves possible to debug optimized output. This makes it reasonable to use the opti- mizer for programs that might have bugs. The following options are useful when GNU CC is generated with the capability for more than one debugging format. -✓-g✓gg✓gd✓db✓b Produce debugging information in the native format (if that is supported), including GDB extensions if at all possible. -✓-g✓gs✓st✓ta✓ab✓bs✓s Produce debugging information in stabs format (if that is supported), without GDB extensions. This GNU Tools 1993/10/13 22 GCC(1) GNU Tools GCC(1) is the format used by DBX on most BSD systems. -✓-g✓gs✓st✓ta✓ab✓bs✓s+✓+ Produce debugging information in stabs format (if that is supported), using GNU extensions understood only by the GNU debugger (GDB). The use of these extensions is likely to make other debuggers crash or refuse to read the program. -✓-g✓gc✓co✓of✓ff✓f Produce debugging information in COFF format (if that is supported). This is the format used by SDB on most System V systems prior to System V Release 4. -✓-g✓gx✓xc✓co✓of✓ff✓f Produce debugging information in XCOFF format (if that is supported). This is the format used by the DBX debugger on IBM RS/6000 systems. -✓-g✓gx✓xc✓co✓of✓ff✓f+✓+ Produce debugging information in XCOFF format (if that is supported), using GNU extensions understood only by the GNU debugger (GDB). The use of these extensions is likely to make other debuggers crash or refuse to read the program. -✓-g✓gd✓dw✓wa✓ar✓rf✓f Produce debugging information in DWARF format (if that is supported). This is the format used by SDB on most System V Release 4 systems. -✓-g✓gd✓dw✓wa✓ar✓rf✓f+✓+ Produce debugging information in DWARF format (if that is supported), using GNU extensions understood only by the GNU debugger (GDB). The use of these extensions is likely to make other debuggers crash or refuse to read the program. -✓-g✓g_✓l_✓e_✓v_✓e_✓l -✓-g✓gg✓gd✓db✓b_✓l_✓e_✓v_✓e_✓l -✓-g✓gs✓st✓ta✓ab✓bs✓s_✓l_✓e_✓v_✓e_✓l -✓-g✓gc✓co✓of✓ff✓f_✓l_✓e_✓v_✓e_✓l -✓-g✓gx✓xc✓co✓of✓ff✓f_✓l_✓e_✓v_✓e_✓l -✓-g✓gd✓dw✓wa✓ar✓rf✓f_✓l_✓e_✓v_✓e_✓l Request debugging information and also use _✓l_✓e_✓v_✓e_✓l to specify how much information. The default level is 2. Level 1 produces minimal information, enough for making backtraces in parts of the program that you don't plan to debug. This includes descriptions of functions and external variables, but no informa- tion about local variables and no line numbers. GNU Tools 1993/10/13 23 GCC(1) GNU Tools GCC(1) Level 3 includes extra information, such as all the macro definitions present in the program. Some de- buggers support macro expansion when you use `-✓-g✓g3✓3'. -✓-p✓p Generate extra code to write profile information suitable for the analysis program p✓pr✓ro✓of✓f. -✓-p✓pg✓g Generate extra code to write profile information suitable for the analysis program g✓gp✓pr✓ro✓of✓f. -✓-a✓a Generate extra code to write profile information for basic blocks, which will record the number of times each basic block is executed. This data could be analyzed by a program like t✓tc✓co✓ov✓v. Note, however, that the format of the data is not what t✓tc✓co✓ov✓v expects. Eventually GNU g✓gp✓pr✓ro✓of✓f should be ex- tended to process this data. -✓-d✓d_✓l_✓e_✓t_✓t_✓e_✓r_✓s Says to make debugging dumps during compilation at times specified by _✓l_✓e_✓t_✓t_✓e_✓r_✓s. This is used for de- bugging the compiler. The file names for most of the dumps are made by appending a word to the source file name (e.g. `f✓fo✓oo✓o.✓.c✓c.✓.r✓rt✓tl✓l' or `f✓fo✓oo✓o.✓.c✓c.✓.j✓ju✓um✓mp✓p'). -✓-d✓dM✓M Dump all macro definitions, at the end of prepro- cessing, and write no output. -✓-d✓dN✓N Dump all macro names, at the end of preprocessing. -✓-d✓dD✓D Dump all macro definitions, at the end of prepro- cessing, in addition to normal output. -✓-d✓dy✓y Dump debugging information during parsing, to stan- dard error. -✓-d✓dr✓r Dump after RTL generation, to `_✓f_✓i_✓l_✓e.✓.r✓rt✓tl✓l'. -✓-d✓dx✓x Just generate RTL for a function instead of compil- ing it. Usually used with `r✓r'. -✓-d✓dj✓j Dump after first jump optimization, to `_✓f_✓i_✓l_✓e.✓.j✓ju✓um✓mp✓p'. -✓-d✓ds✓s Dump after CSE (including the jump optimization that sometimes follows CSE), to `_✓f_✓i_✓l_✓e.✓.c✓cs✓se✓e'. -✓-d✓dL✓L Dump after loop optimization, to `_✓f_✓i_✓l_✓e.✓.l✓lo✓oo✓op✓p'. -✓-d✓dt✓t Dump after the second CSE pass (including the jump optimization that sometimes follows CSE), to `_✓f_✓i_✓l_✓e.✓.c✓cs✓se✓e2✓2'. -✓-d✓df✓f Dump after flow analysis, to `_✓f_✓i_✓l_✓e.✓.f✓fl✓lo✓ow✓w'. GNU Tools 1993/10/13 24 GCC(1) GNU Tools GCC(1) -✓-d✓dc✓c Dump after instruction combination, to `_✓f_✓i_✓l_✓e.✓.c✓co✓om✓mb✓bi✓in✓ne✓e'. -✓-d✓dS✓S Dump after the first instruction scheduling pass, to `_✓f_✓i_✓l_✓e.✓.s✓sc✓ch✓he✓ed✓d'. -✓-d✓dl✓l Dump after local register allocation, to `_✓f_✓i_✓l_✓e.✓.l✓lr✓re✓eg✓g'. -✓-d✓dg✓g Dump after global register allocation, to `_✓f_✓i_✓l_✓e.✓.g✓gr✓re✓eg✓g'. -✓-d✓dR✓R Dump after the second instruction scheduling pass, to `_✓f_✓i_✓l_✓e.✓.s✓sc✓ch✓he✓ed✓d2✓2'. -✓-d✓dJ✓J Dump after last jump optimization, to `_✓f_✓i_✓l_✓e.✓.j✓ju✓um✓mp✓p2✓2'. -✓-d✓dd✓d Dump after delayed branch scheduling, to `_✓f_✓i_✓l_✓e.✓.d✓db✓br✓r'. -✓-d✓dk✓k Dump after conversion from registers to stack, to `_✓f_✓i_✓l_✓e.✓.s✓st✓ta✓ac✓ck✓k'. -✓-d✓da✓a Produce all the dumps listed above. -✓-d✓dm✓m Print statistics on memory usage, at the end of the run, to standard error. -✓-d✓dp✓p Annotate the assembler output with a comment indi- cating which pattern and alternative was used. -✓-f✓fp✓pr✓re✓et✓te✓en✓nd✓d-✓-f✓fl✓lo✓oa✓at✓t When running a cross-compiler, pretend that the target machine uses the same floating point format as the host machine. This causes incorrect output of the actual floating constants, but the actual instruction sequence will probably be the same as GNU CC would make when running on the target ma- chine. -✓-s✓sa✓av✓ve✓e-✓-t✓te✓em✓mp✓ps✓s Store the usual "temporary" intermediate files per- manently; place them in the current directory and name them based on the source file. Thus, compil- ing `f✓fo✓oo✓o.✓.c✓c' with `-✓-c✓c -✓-s✓sa✓av✓ve✓e-✓-t✓te✓em✓mp✓ps✓s' would produce files `f✓fo✓oo✓o.✓.c✓cp✓pp✓p' and `f✓fo✓oo✓o.✓.s✓s', as well as `f✓fo✓oo✓o.✓.o✓o'. -✓-p✓pr✓ri✓in✓nt✓t-✓-f✓fi✓il✓le✓e-✓-n✓na✓am✓me✓e=✓=_✓l_✓i_✓b_✓r_✓a_✓r_✓y Print the full absolute name of the library file _✓l_✓i_✓b_✓r_✓a_✓r_✓y that would be used when linking--and do not do anything else. With this option, GNU CC does not compile or link anything; it just prints the file name. GNU Tools 1993/10/13 25 GCC(1) GNU Tools GCC(1) -✓-p✓pr✓ri✓in✓nt✓t-✓-l✓li✓ib✓bg✓gc✓cc✓c-✓-f✓fi✓il✓le✓e-✓-n✓na✓am✓me✓e Same as `-✓-p✓pr✓ri✓in✓nt✓t-✓-f✓fi✓il✓le✓e-✓-n✓na✓am✓me✓e=✓=l✓li✓ib✓bg✓gc✓cc✓c.✓.a✓a'. -✓-p✓pr✓ri✓in✓nt✓t-✓-p✓pr✓ro✓og✓g-✓-n✓na✓am✓me✓e=✓=_✓p_✓r_✓o_✓g_✓r_✓a_✓m Like `-✓-p✓pr✓ri✓in✓nt✓t-✓-f✓fi✓il✓le✓e-✓-n✓na✓am✓me✓e', but searches for a program such as `cpp'. O✓OP✓PT✓TI✓IM✓MI✓IZ✓ZA✓AT✓TI✓IO✓ON✓N O✓OP✓PT✓TI✓IO✓ON✓NS✓S These options control various sorts of optimizations: -✓-O✓O -✓-O✓O1✓1 Optimize. Optimizing compilation takes somewhat more time, and a lot more memory for a large func- tion. Without `-✓-O✓O', the compiler's goal is to reduce the cost of compilation and to make debugging produce the expected results. Statements are independent: if you stop the program with a breakpoint between statements, you can then assign a new value to any variable or change the program counter to any other statement in the function and get exactly the re- sults you would expect from the source code. Without `-✓-O✓O', only variables declared r✓re✓eg✓gi✓is✓st✓te✓er✓r are allocated in registers. The resulting compiled code is a little worse than produced by PCC without `-✓-O✓O'. With `-✓-O✓O', the compiler tries to reduce code size and execution time. When you specify `-✓-O✓O', the two options `-✓-f✓ft✓th✓hr✓re✓ea✓ad✓d-✓-j✓ju✓um✓mp✓ps✓s' and `-✓-f✓fd✓de✓ef✓fe✓er✓r-✓-p✓po✓op✓p' are turned on. On machines that have delay slots, the `-✓-f✓fd✓de✓el✓la✓ay✓ye✓ed✓d-✓-b✓br✓ra✓an✓nc✓ch✓h' option is turned on. For those machines that can support debugging even without a frame pointer, the `-✓-f✓fo✓om✓mi✓it✓t-✓-f✓fr✓ra✓am✓me✓e-✓-p✓po✓oi✓in✓nt✓te✓er✓r' option is turned on. On some machines other flags may also be turned on. -✓-O✓O2✓2 Optimize even more. Nearly all supported optimiza- tions that do not involve a space-speed tradeoff are performed. Loop unrolling and function inlin- ing are not done, for example. As compared to -✓-O✓O, this option increases both compilation time and the performance of the generated code. -✓-O✓O3✓3 Optimize yet more. This turns on everything -✓-O✓O2✓2 does, along with also turning on -✓-f✓fi✓in✓n-✓- l✓li✓in✓ne✓e-✓-f✓fu✓un✓nc✓ct✓ti✓io✓on✓ns✓s.✓. -✓-O✓O0✓0 Do not optimize. GNU Tools 1993/10/13 26 GCC(1) GNU Tools GCC(1) If you use multiple -✓-O✓O options, with or without level numbers, the last such option is the one that is effective. Options of the form `-✓-f✓f_✓f_✓l_✓a_✓g' specify machine-independent flags. Most flags have both positive and negative forms; the negative form of `-✓-f✓ff✓fo✓oo✓o' would be `-✓-f✓fn✓no✓o-✓-f✓fo✓oo✓o'. The following list shows only one form--the one which is not the default. You can figure out the other form by either removing `n✓no✓o-✓-' or adding it. -✓-f✓ff✓fl✓lo✓oa✓at✓t-✓-s✓st✓to✓or✓re✓e Do not store floating point variables in registers. This prevents undesirable excess precision on ma- chines such as the 68000 where the floating regis- ters (of the 68881) keep more precision than a d✓do✓ou✓u-✓- b✓bl✓le✓e is supposed to have. For most programs, the excess precision does only good, but a few programs rely on the precise defi- nition of IEEE floating point. Use `-✓-f✓ff✓fl✓lo✓oa✓at✓t-✓-s✓st✓to✓or✓re✓e' for such programs. -✓-f✓fm✓me✓em✓mo✓oi✓iz✓ze✓e-✓-l✓lo✓oo✓ok✓ku✓up✓ps✓s -✓-f✓fs✓sa✓av✓ve✓e-✓-m✓me✓em✓mo✓oi✓iz✓ze✓ed✓d Use heuristics to compile faster (C++ only). These heuristics are not enabled by default, since they are only effective for certain input files. Other input files compile more slowly. The first time the compiler must build a call to a member function (or reference to a data member), it must (1) determine whether the class implements member functions of that name; (2) resolve which member function to call (which involves figuring out what sorts of type conversions need to be made); and (3) check the visibility of the member function to the caller. All of this adds up to slower compilation. Normally, the second time a call is made to that member function (or reference to that data member), it must go through the same lengthy process again. This means that code like this cout << "This " << p << " has " << n << " legs.\n"; makes six passes through all three steps. By using a software cache, a "hit" significantly reduces this cost. Unfortunately, using the cache intro- duces another layer of mechanisms which must be im- plemented, and so incurs its own overhead. `-✓-f✓fm✓me✓em✓mo✓oi✓iz✓ze✓e-✓-l✓lo✓oo✓ok✓ku✓up✓ps✓s' enables the software cache. GNU Tools 1993/10/13 27 GCC(1) GNU Tools GCC(1) Because access privileges (visibility) to members and member functions may differ from one function context to the next, g✓g+✓++✓+ may need to flush the cache. With the `-✓-f✓fm✓me✓em✓mo✓oi✓iz✓ze✓e-✓-l✓lo✓oo✓ok✓ku✓up✓ps✓s' flag, the cache is flushed after every function that is com- piled. The `-fsave-memoized' flag enables the same software cache, but when the compiler determines that the context of the last function compiled would yield the same access privileges of the next function to compile, it preserves the cache. This is most helpful when defining many member functions for the same class: with the exception of member functions which are friends of other classes, each member function has exactly the same access privi- leges as every other, and the cache need not be flushed. -✓-f✓fn✓no✓o-✓-d✓de✓ef✓fa✓au✓ul✓lt✓t-✓-i✓in✓nl✓li✓in✓ne✓e Don't make member functions inline by default mere- ly because they are defined inside the class scope (C++ only). -✓-f✓fn✓no✓o-✓-d✓de✓ef✓fe✓er✓r-✓-p✓po✓op✓p Always pop the arguments to each function call as soon as that function returns. For machines which must pop arguments after a function call, the com- piler normally lets arguments accumulate on the stack for several function calls and pops them all at once. -✓-f✓ff✓fo✓or✓rc✓ce✓e-✓-m✓me✓em✓m Force memory operands to be copied into registers before doing arithmetic on them. This may produce better code by making all memory references poten- tial common subexpressions. When they are not com- mon subexpressions, instruction combination should eliminate the separate register-load. I am inter- ested in hearing about the difference this makes. -✓-f✓ff✓fo✓or✓rc✓ce✓e-✓-a✓ad✓dd✓dr✓r Force memory address constants to be copied into registers before doing arithmetic on them. This may produce better code just as `-✓-f✓ff✓fo✓or✓rc✓ce✓e-✓-m✓me✓em✓m' may. I am interested in hearing about the difference this makes. -✓-f✓fo✓om✓mi✓it✓t-✓-f✓fr✓ra✓am✓me✓e-✓-p✓po✓oi✓in✓nt✓te✓er✓r Don't keep the frame pointer in a register for functions that don't need one. This avoids the in- structions to save, set up and restore frame point- ers; it also makes an extra register available in many functions. _✓I_✓t _✓a_✓l_✓s_✓o _✓m_✓a_✓k_✓e_✓s _✓d_✓e_✓b_✓u_✓g_✓g_✓i_✓n_✓g _✓i_✓m_✓p_✓o_✓s_✓s_✓i_✓b_✓l_✓e _✓o_✓n most machines. GNU Tools 1993/10/13 28 GCC(1) GNU Tools GCC(1) On some machines, such as the Vax, this flag has no effect, because the standard calling sequence auto- matically handles the frame pointer and nothing is saved by pretending it doesn't exist. The machine- description macro F✓FR✓RA✓AM✓ME✓E_✓_P✓PO✓OI✓IN✓NT✓TE✓ER✓R_✓_R✓RE✓EQ✓QU✓UI✓IR✓RE✓ED✓D controls whether a target machine supports this flag. -✓-f✓fi✓in✓nl✓li✓in✓ne✓e-✓-f✓fu✓un✓nc✓ct✓ti✓io✓on✓ns✓s Integrate all simple functions into their callers. The compiler heuristically decides which functions are simple enough to be worth integrating in this way. If all calls to a given function are integrated, and the function is declared s✓st✓ta✓at✓ti✓ic✓c, then GCC nor- mally does not output the function as assembler code in its own right. -✓-f✓fc✓ca✓al✓ll✓le✓er✓r-✓-s✓sa✓av✓ve✓es✓s Enable values to be allocated in registers that will be clobbered by function calls, by emitting extra instructions to save and restore the regis- ters around such calls. Such allocation is done only when it seems to result in better code than would otherwise be produced. This option is enabled by default on certain ma- chines, usually those which have no call-preserved registers to use instead. -✓-f✓fk✓ke✓ee✓ep✓p-✓-i✓in✓nl✓li✓in✓ne✓e-✓-f✓fu✓un✓nc✓ct✓ti✓io✓on✓ns✓s Even if all calls to a given function are integrat- ed, and the function is declared s✓st✓ta✓at✓ti✓ic✓c, neverthe- less output a separate run-time callable version of the function. -✓-f✓fn✓no✓o-✓-f✓fu✓un✓nc✓ct✓ti✓io✓on✓n-✓-c✓cs✓se✓e Do not put function addresses in registers; make each instruction that calls a constant function contain the function's address explicitly. This option results in less efficient code, but some strange hacks that alter the assembler output may be confused by the optimizations performed when this option is not used. -✓-f✓fn✓no✓o-✓-p✓pe✓ee✓ep✓ph✓ho✓ol✓le✓e Disable any machine-specific peephole optimiza- tions. -✓-f✓ff✓fa✓as✓st✓t-✓-m✓ma✓at✓th✓h This option allows GCC to violate some ANSI or IEEE rules/specifications in the interest of optimizing code for speed. For example, it allows the compil- GNU Tools 1993/10/13 29 GCC(1) GNU Tools GCC(1) er to assume arguments to the s✓sq✓qr✓rt✓t function are non-negative numbers. This option should never be turned on by any `-✓-O✓O' option since it can result in incorrect output for programs which depend on an exact implementation of IEEE or ANSI rules/specifications for math func- tions. The following options control specific optimizations. The `-✓-O✓O2✓2' option turns on all of these optimizations except `-✓-f✓fu✓un✓nr✓ro✓ol✓ll✓l-✓-l✓lo✓oo✓op✓ps✓s' and `-✓-f✓fu✓un✓nr✓ro✓ol✓ll✓l-✓-a✓al✓ll✓l-✓-l✓lo✓oo✓op✓ps✓s'. The `-✓-O✓O' option usually turns on the `-✓-f✓ft✓th✓hr✓re✓ea✓ad✓d-✓-j✓ju✓um✓mp✓ps✓s' and `-✓-f✓fd✓de✓el✓la✓ay✓ye✓ed✓d-✓-b✓br✓ra✓an✓nc✓ch✓h' options, but specific machines may change the default optimizations. You can use the following flags in the rare cases when "fine-tuning" of optimizations to be performed is desired. -✓-f✓fs✓st✓tr✓re✓en✓ng✓gt✓th✓h-✓-r✓re✓ed✓du✓uc✓ce✓e Perform the optimizations of loop strength reduc- tion and elimination of iteration variables. -✓-f✓ft✓th✓hr✓re✓ea✓ad✓d-✓-j✓ju✓um✓mp✓ps✓s Perform optimizations where we check to see if a jump branches to a location where another compari- son subsumed by the first is found. If so, the first branch is redirected to either the destina- tion of the second branch or a point immediately following it, depending on whether the condition is known to be true or false. -✓-f✓fu✓un✓nr✓ro✓ol✓ll✓l-✓-l✓lo✓oo✓op✓ps✓s Perform the optimization of loop unrolling. This is only done for loops whose number of iterations can be determined at compile time or run time. -✓-f✓fu✓un✓nr✓ro✓ol✓ll✓l-✓-a✓al✓ll✓l-✓-l✓lo✓oo✓op✓ps✓s Perform the optimization of loop unrolling. This is done for all loops. This usually makes programs run more slowly. -✓-f✓fc✓cs✓se✓e-✓-f✓fo✓ol✓ll✓lo✓ow✓w-✓-j✓ju✓um✓mp✓ps✓s In common subexpression elimination, scan through jump instructions when the target of the jump is not reached by any other path. For example, when CSE encounters an i✓if✓f statement with an e✓el✓ls✓se✓e clause, CSE will follow the jump when the condition tested is false. -✓-f✓fc✓cs✓se✓e-✓-s✓sk✓ki✓ip✓p-✓-b✓bl✓lo✓oc✓ck✓ks✓s This is similar to `-✓-f✓fc✓cs✓se✓e-✓-f✓fo✓ol✓ll✓lo✓ow✓w-✓-j✓ju✓um✓mp✓ps✓s', but causes CSE to follow jumps which conditionally skip over GNU Tools 1993/10/13 30 GCC(1) GNU Tools GCC(1) blocks. When CSE encounters a simple i✓if✓f statement with no else clause, `-✓-f✓fc✓cs✓se✓e-✓-s✓sk✓ki✓ip✓p-✓-b✓bl✓lo✓oc✓ck✓ks✓s' causes CSE to follow the jump around the body of the i✓if✓f. -✓-f✓fr✓re✓er✓ru✓un✓n-✓-c✓cs✓se✓e-✓-a✓af✓ft✓te✓er✓r-✓-l✓lo✓oo✓op✓p Re-run common subexpression elimination after loop optimizations has been performed. -✓-f✓fe✓el✓li✓id✓de✓e-✓-c✓co✓on✓ns✓st✓tr✓ru✓uc✓ct✓to✓or✓rs✓s Elide constructors when this seems plausible (C++ only). With this flag, GNU C++ initializes y✓y di- rectly from the call to f✓fo✓oo✓o without going through a temporary in the following code: A foo (); A y = foo (); Without this option, GNU C++ first initializes y✓y by calling the appropriate constructor for type A✓A; then assigns the result of f✓fo✓oo✓o to a temporary; and, finally, replaces the initial valyue of `y✓y' with the temporary. The default behavior (`-✓-f✓fn✓no✓o-✓-e✓el✓li✓id✓de✓e-✓-c✓co✓on✓ns✓st✓tr✓ru✓uc✓ct✓to✓or✓rs✓s') is specified by the draft ANSI C++ standard. If your program's constructors have side effects, using `-✓-f✓fe✓el✓li✓id✓de✓e-✓-c✓co✓on✓ns✓st✓tr✓ru✓uc✓ct✓to✓or✓rs✓s' can make your program act differently, since some constructor calls may be omitted. -✓-f✓fe✓ex✓xp✓pe✓en✓ns✓si✓iv✓ve✓e-✓-o✓op✓pt✓ti✓im✓mi✓iz✓za✓at✓ti✓io✓on✓ns✓s Perform a number of minor optimizations that are relatively expensive. -✓-f✓fd✓de✓el✓la✓ay✓ye✓ed✓d-✓-b✓br✓ra✓an✓nc✓ch✓h If supported for the target machine, attempt to re- order instructions to exploit instruction slots available after delayed branch instructions. -✓-f✓fs✓sc✓ch✓he✓ed✓du✓ul✓le✓e-✓-i✓in✓ns✓sn✓ns✓s If supported for the target machine, attempt to re- order instructions to eliminate execution stalls due to required data being unavailable. This helps machines that have slow floating point or memory load instructions by allowing other instructions to be issued until the result of the load or floating point instruction is required. -✓-f✓fs✓sc✓ch✓he✓ed✓du✓ul✓le✓e-✓-i✓in✓ns✓sn✓ns✓s2✓2 Similar to `-✓-f✓fs✓sc✓ch✓he✓ed✓du✓ul✓le✓e-✓-i✓in✓ns✓sn✓ns✓s', but requests an ad- ditional pass of instruction scheduling after reg- ister allocation has been done. This is especially useful on machines with a relatively small number of registers and where memory load instructions take more than one cycle. GNU Tools 1993/10/13 31 GCC(1) GNU Tools GCC(1) T✓TA✓AR✓RG✓GE✓ET✓T O✓OP✓PT✓TI✓IO✓ON✓NS✓S By default, GNU CC compiles code for the same type of ma- chine that you are using. However, it can also be in- stalled as a cross-compiler, to compile for some other type of machine. In fact, several different configura- tions of GNU CC, for different target machines, can be in- stalled side by side. Then you specify which one to use with the `-✓-b✓b' option. In addition, older and newer versions of GNU CC can be in- stalled side by side. One of them (probably the newest) will be the default, but you may sometimes wish to use an- other. -✓-b✓b _✓m_✓a_✓c_✓h_✓i_✓n_✓e The argument _✓m_✓a_✓c_✓h_✓i_✓n_✓e specifies the target machine for compilation. This is useful when you have in- stalled GNU CC as a cross-compiler. The value to use for _✓m_✓a_✓c_✓h_✓i_✓n_✓e is the same as was specified as the machine type when configuring GNU CC as a cross-compiler. For example, if a cross- compiler was configured with `c✓co✓on✓nf✓fi✓ig✓gu✓ur✓re✓e i386v', meaning to compile for an 80386 running System V, then you would specify `-✓-b✓b i✓i3✓38✓86✓6v✓v' to run that cross compiler. When you do not specify `-✓-b✓b', it normally means to compile for the same type of machine that you are using. -✓-V✓V _✓v_✓e_✓r_✓s_✓i_✓o_✓n The argument _✓v_✓e_✓r_✓s_✓i_✓o_✓n specifies which version of GNU CC to run. This is useful when multiple versions are installed. For example, _✓v_✓e_✓r_✓s_✓i_✓o_✓n might be `2✓2.✓.0✓0', meaning to run GNU CC version 2.0. The default version, when you do not specify `-✓-V✓V', is controlled by the way GNU CC is installed. Nor- mally, it will be a version that is recommended for general use. M✓MA✓AC✓CH✓HI✓IN✓NE✓E D✓DE✓EP✓PE✓EN✓ND✓DE✓EN✓NT✓T O✓OP✓PT✓TI✓IO✓ON✓NS✓S Each of the target machine types can have its own special options, starting with `-✓-m✓m', to choose among various hard- ware models or configurations--for example, 68010 vs 68020, floating coprocessor or none. A single installed version of the compiler can compile for any model or con- figuration, according to the options specified. Some configurations of the compiler also support addition- al special options, usually for command-line compatibility with other compilers on the same platform. GNU Tools 1993/10/13 32 GCC(1) GNU Tools GCC(1) These are the `-✓-m✓m' options defined for the 68000 series: -✓-m✓m6✓68✓80✓00✓00✓0 -✓-m✓mc✓c6✓68✓80✓00✓00✓0 Generate output for a 68000. This is the default when the compiler is configured for 68000-based systems. -✓-m✓m6✓68✓80✓02✓20✓0 -✓-m✓mc✓c6✓68✓80✓02✓20✓0 Generate output for a 68020 (rather than a 68000). This is the default when the compiler is configured for 68020-based systems. -✓-m✓m6✓68✓88✓88✓81✓1 Generate output containing 68881 instructions for floating point. This is the default for most 68020-based systems unless -✓-n✓nf✓fp✓p was specified when the compiler was configured. -✓-m✓m6✓68✓80✓03✓30✓0 Generate output for a 68030. This is the default when the compiler is configured for 68030-based systems. -✓-m✓m6✓68✓80✓04✓40✓0 Generate output for a 68040. This is the default when the compiler is configured for 68040-based systems. -✓-m✓m6✓68✓80✓02✓20✓0-✓-4✓40✓0 Generate output for a 68040, without using any of the new instructions. This results in code which can run relatively efficiently on either a 68020/68881 or a 68030 or a 68040. -✓-m✓mf✓fp✓pa✓a Generate output containing Sun FPA instructions for floating point. -✓-m✓ms✓so✓of✓ft✓t-✓-f✓fl✓lo✓oa✓at✓t Generate output containing library calls for float- ing point. _✓W_✓A_✓R_✓N_✓I_✓N_✓G_✓: the requisite libraries are not part of GNU CC. Normally the facilities of the machine's usual C compiler are used, but this can't be done directly in cross-compilation. You must make your own arrangements to provide suitable li- brary functions for cross-compilation. -✓-m✓ms✓sh✓ho✓or✓rt✓t Consider type i✓in✓nt✓t to be 16 bits wide, like s✓sh✓ho✓or✓rt✓t i✓in✓nt✓t. GNU Tools 1993/10/13 33 GCC(1) GNU Tools GCC(1) -✓-m✓mn✓no✓ob✓bi✓it✓tf✓fi✓ie✓el✓ld✓d Do not use the bit-field instructions. `-✓-m✓m6✓68✓80✓00✓00✓0' implies `-✓-m✓mn✓no✓ob✓bi✓it✓tf✓fi✓ie✓el✓ld✓d'. -✓-m✓mb✓bi✓it✓tf✓fi✓ie✓el✓ld✓d Do use the bit-field instructions. `-✓-m✓m6✓68✓80✓02✓20✓0' im- plies `-✓-m✓mb✓bi✓it✓tf✓fi✓ie✓el✓ld✓d'. This is the default if you use the unmodified sources. -✓-m✓mr✓rt✓td✓d Use a different function-calling convention, in which functions that take a fixed number of argu- ments return with the r✓rt✓td✓d instruction, which pops their arguments while returning. This saves one instruction in the caller since there is no need to pop the arguments there. This calling convention is incompatible with the one normally used on Unix, so you cannot use it if you need to call libraries compiled with the Unix compiler. Also, you must provide function prototypes for all functions that take variable numbers of arguments (including p✓pr✓ri✓in✓nt✓tf✓f); otherwise incorrect code will be generated for calls to those functions. In addition, seriously incorrect code will result if you call a function with too many arguments. (Normally, extra arguments are harmlessly ignored.) The r✓rt✓td✓d instruction is supported by the 68010 and 68020 processors, but not by the 68000. These `-✓-m✓m' options are defined for the Vax: -✓-m✓mu✓un✓ni✓ix✓x Do not output certain jump instructions (a✓ao✓ob✓bl✓le✓eq✓q and so on) that the Unix assembler for the Vax cannot handle across long ranges. -✓-m✓mg✓gn✓nu✓u Do output those jump instructions, on the assump- tion that you will assemble with the GNU assembler. -✓-m✓mg✓g Output code for g-format floating point numbers in- stead of d-format. These `-✓-m✓m' switches are supported on the SPARC: -✓-m✓mf✓fp✓pu✓u -✓-m✓mh✓ha✓ar✓rd✓d-✓-f✓fl✓lo✓oa✓at✓t Generate output containing floating point instruc- tions. This is the default. -✓-m✓mn✓no✓o-✓-f✓fp✓pu✓u GNU Tools 1993/10/13 34 GCC(1) GNU Tools GCC(1) -✓-m✓ms✓so✓of✓ft✓t-✓-f✓fl✓lo✓oa✓at✓t Generate output containing library calls for float- ing point. _✓W_✓a_✓r_✓n_✓i_✓n_✓g_✓: there is no GNU floating-point library for SPARC. Normally the facilities of the machine's usual C compiler are used, but this can- not be done directly in cross-compilation. You must make your own arrangements to provide suitable library functions for cross-compilation. -✓-m✓ms✓so✓of✓ft✓t-✓-f✓fl✓lo✓oa✓at✓t changes the calling convention in the output file; therefore, it is only useful if you compile _✓a_✓l_✓l of a program with this option. -✓-m✓mn✓no✓o-✓-e✓ep✓pi✓il✓lo✓og✓gu✓ue✓e -✓-m✓me✓ep✓pi✓il✓lo✓og✓gu✓ue✓e With -✓-m✓me✓ep✓pi✓il✓lo✓og✓gu✓ue✓e (the default), the compiler always emits code for function exit at the end of each function. Any function exit in the middle of the function (such as a return statement in C) will generate a jump to the exit code at the end of the function. With -✓-m✓mn✓no✓o-✓-e✓ep✓pi✓il✓lo✓og✓gu✓ue✓e, the compiler tries to emit exit code inline at every function exit. -✓-m✓mn✓no✓o-✓-v✓v8✓8 -✓-m✓mv✓v8✓8 -✓-m✓ms✓sp✓pa✓ar✓rc✓cl✓li✓it✓te✓e These three options select variations on the SPARC architecture. By default (unless specifically configured for the Fujitsu SPARClite), GCC generates code for the v7 variant of the SPARC architecture. -✓-m✓mv✓v8✓8 will give you SPARC v8 code. The only differ- ence from v7 code is that the compiler emits the integer multiply and integer divide instructions which exist in SPARC v8 but not in SPARC v7. -✓-m✓ms✓sp✓pa✓ar✓rc✓cl✓li✓it✓te✓e will give you SPARClite code. This adds the integer multiply, integer divide step and scan (ffs) instructions which exist in SPARClite but not in SPARC v7. -✓-m✓mc✓cy✓yp✓pr✓re✓es✓ss✓s -✓-m✓ms✓su✓up✓pe✓er✓rs✓sp✓pa✓ar✓rc✓c These two options select the processor for which the code is optimised. GNU Tools 1993/10/13 35 GCC(1) GNU Tools GCC(1) With -✓-m✓mc✓cy✓yp✓pr✓re✓es✓ss✓s (the default), the compiler optimis- es code for the Cypress CY7C602 chip, as used in the SparcStation/SparcSever 3xx series. This is al- so apropriate for the older SparcStation 1, 2, IPX etc. With -✓-m✓ms✓su✓up✓pe✓er✓rs✓sp✓pa✓ar✓rc✓c the compiler optimises code for the SuperSparc cpu, as used in the SparcStation 10, 1000 and 2000 series. This flag also enables use of the full SPARC v8 instruction set. These `-✓-m✓m' options are defined for the Convex: -✓-m✓mc✓c1✓1 Generate output for a C1. This is the default when the compiler is configured for a C1. -✓-m✓mc✓c2✓2 Generate output for a C2. This is the default when the compiler is configured for a C2. -✓-m✓ma✓ar✓rg✓gc✓co✓ou✓un✓nt✓t Generate code which puts an argument count in the word preceding each argument list. Some non- portable Convex and Vax programs need this word. (Debuggers don't, except for functions with vari- able-length argument lists; this info is in the symbol table.) -✓-m✓mn✓no✓oa✓ar✓rg✓gc✓co✓ou✓un✓nt✓t Omit the argument count word. This is the default if you use the unmodified sources. These `-✓-m✓m' options are defined for the AMD Am29000: -✓-m✓md✓dw✓w Generate code that assumes the DW bit is set, i.e., that byte and halfword operations are directly sup- ported by the hardware. This is the default. -✓-m✓mn✓no✓od✓dw✓w Generate code that assumes the DW bit is not set. -✓-m✓mb✓bw✓w Generate code that assumes the system supports byte and halfword write operations. This is the de- fault. -✓-m✓mn✓nb✓bw✓w Generate code that assumes the systems does not support byte and halfword write operations. This implies `-✓-m✓mn✓no✓od✓dw✓w'. -✓-m✓ms✓sm✓ma✓al✓ll✓l Use a small memory model that assumes that all function addresses are either within a single 256 KB segment or at an absolute address of less than 256K. This allows the c✓ca✓al✓ll✓l instruction to be used instead of a c✓co✓on✓ns✓st✓t, c✓co✓on✓ns✓st✓th✓h, c✓ca✓al✓ll✓li✓i sequence. GNU Tools 1993/10/13 36 GCC(1) GNU Tools GCC(1) -✓-m✓ml✓la✓ar✓rg✓ge✓e Do not assume that the c✓ca✓al✓ll✓l instruction can be used; this is the default. -✓-m✓m2✓29✓90✓05✓50✓0 Generate code for the Am29050. -✓-m✓m2✓29✓90✓00✓00✓0 Generate code for the Am29000. This is the de- fault. -✓-m✓mk✓ke✓er✓rn✓ne✓el✓l-✓-r✓re✓eg✓gi✓is✓st✓te✓er✓rs✓s Generate references to registers g✓gr✓r6✓64✓4-✓-g✓gr✓r9✓95✓5 instead of g✓gr✓r9✓96✓6-✓-g✓gr✓r1✓12✓27✓7. This option can be used when com- piling kernel code that wants a set of global reg- isters disjoint from that used by user-mode code. Note that when this option is used, register names in `-✓-f✓f' flags must use the normal, user-mode, names. -✓-m✓mu✓us✓se✓er✓r-✓-r✓re✓eg✓gi✓is✓st✓te✓er✓rs✓s Use the normal set of global registers, g✓gr✓r9✓96✓6-✓-g✓gr✓r1✓12✓27✓7. This is the default. -✓-m✓ms✓st✓ta✓ac✓ck✓k-✓-c✓ch✓he✓ec✓ck✓k Insert a call to _✓__✓_m✓ms✓sp✓p_✓_c✓ch✓he✓ec✓ck✓k after each stack ad- justment. This is often used for kernel code. These `-✓-m✓m' options are defined for Motorola 88K architec- tures: -✓-m✓m8✓88✓80✓00✓00✓0 Generate code that works well on both the m88100 and the m88110. -✓-m✓m8✓88✓81✓10✓00✓0 Generate code that works best for the m88100, but that also runs on the m88110. -✓-m✓m8✓88✓81✓11✓10✓0 Generate code that works best for the m88110, and may not run on the m88100. -✓-m✓mi✓id✓de✓en✓nt✓ti✓if✓fy✓y-✓-r✓re✓ev✓vi✓is✓si✓io✓on✓n Include an i✓id✓de✓en✓nt✓t directive in the assembler output recording the source file name, compiler name and version, timestamp, and compilation flags used. -✓-m✓mn✓no✓o-✓-u✓un✓nd✓de✓er✓rs✓sc✓co✓or✓re✓es✓s In assembler output, emit symbol names without adding an underscore character at the beginning of each name. The default is to use an underscore as prefix on each name. GNU Tools 1993/10/13 37 GCC(1) GNU Tools GCC(1) -✓-m✓mn✓no✓o-✓-c✓ch✓he✓ec✓ck✓k-✓-z✓ze✓er✓ro✓o-✓-d✓di✓iv✓vi✓is✓si✓io✓on✓n -✓-m✓mc✓ch✓he✓ec✓ck✓k-✓-z✓ze✓er✓ro✓o-✓-d✓di✓iv✓vi✓is✓si✓io✓on✓n Early models of the 88K architecture had problems with division by zero; in particular, many of them didn't trap. Use these options to avoid including (or to include explicitly) additional code to de- tect division by zero and signal an exception. All GCC configurations for the 88K use `-✓-m✓mc✓ch✓he✓ec✓ck✓k-✓-z✓ze✓er✓ro✓o-✓-d✓di✓iv✓vi✓is✓si✓io✓on✓n' by default. -✓-m✓mo✓oc✓cs✓s-✓-d✓de✓eb✓bu✓ug✓g-✓-i✓in✓nf✓fo✓o -✓-m✓mn✓no✓o-✓-o✓oc✓cs✓s-✓-d✓de✓eb✓bu✓ug✓g-✓-i✓in✓nf✓fo✓o Include (or omit) additional debugging information (about registers used in each stack frame) as spec- ified in the 88Open Object Compatibility Standard, "OCS". This extra information is not needed by GDB. The default for DG/UX, SVr4, and Delta 88 SVr3.2 is to include this information; other 88k configurations omit this information by default. -✓-m✓mo✓oc✓cs✓s-✓-f✓fr✓ra✓am✓me✓e-✓-p✓po✓os✓si✓it✓ti✓io✓on✓n -✓-m✓mn✓no✓o-✓-o✓oc✓cs✓s-✓-f✓fr✓ra✓am✓me✓e-✓-p✓po✓os✓si✓it✓ti✓io✓on✓n Force (or do not require) register values to be stored in a particular place in stack frames, as specified in OCS. The DG/UX, Delta88 SVr3.2, and BCS configurations use `-✓-m✓mo✓oc✓cs✓s-✓-f✓fr✓ra✓am✓me✓e-✓-p✓po✓os✓si✓it✓ti✓io✓on✓n'; oth- er 88k configurations have the default `-✓-m✓mn✓no✓o-✓-o✓oc✓cs✓s-✓-f✓fr✓ra✓am✓me✓e-✓-p✓po✓os✓si✓it✓ti✓io✓on✓n'. -✓-m✓mo✓op✓pt✓ti✓im✓mi✓iz✓ze✓e-✓-a✓ar✓rg✓g-✓-a✓ar✓re✓ea✓a -✓-m✓mn✓no✓o-✓-o✓op✓pt✓ti✓im✓mi✓iz✓ze✓e-✓-a✓ar✓rg✓g-✓-a✓ar✓re✓ea✓a Control how to store function arguments in stack frames. `-✓-m✓mo✓op✓pt✓ti✓im✓mi✓iz✓ze✓e-✓-a✓ar✓rg✓g-✓-a✓ar✓re✓ea✓a' saves space, but may break some debuggers (not GDB). `-✓-m✓mn✓no✓o-✓-o✓op✓pt✓ti✓im✓mi✓iz✓ze✓e-✓-a✓ar✓rg✓g-✓-a✓ar✓re✓ea✓a' conforms better to stan- dards. By default GCC does not optimize the argu- ment area. -✓-m✓ms✓sh✓ho✓or✓rt✓t-✓-d✓da✓at✓ta✓a-✓-_✓n_✓u_✓m _✓n_✓u_✓m Generate smaller data references by making them relative to r✓r0✓0, which allows loading a value using a single instruction (rather than the usual two). You control which data references are affected by specifying _✓n_✓u_✓m with this option. For example, if you specify `-✓-m✓ms✓sh✓ho✓or✓rt✓t-✓-d✓da✓at✓ta✓a-✓-5✓51✓12✓2', then the data ref- erences affected are those involving displacements of less than 512 bytes. `-✓-m✓ms✓sh✓ho✓or✓rt✓t-✓-d✓da✓at✓ta✓a-✓-_✓n_✓u_✓m' is not effective for _✓n_✓u_✓m greater than 64K. -✓-m✓ms✓se✓er✓ri✓ia✓al✓li✓iz✓ze✓e-✓-v✓vo✓ol✓la✓at✓ti✓il✓le✓e GNU Tools 1993/10/13 38 GCC(1) GNU Tools GCC(1) -✓-m✓mn✓no✓o-✓-s✓se✓er✓ri✓ia✓al✓li✓iz✓ze✓e-✓-v✓vo✓ol✓la✓at✓ti✓il✓le✓e Do, or do not, generate code to guarantee sequen- tial consistency of volatile memory references. GNU CC always guarantees consistency by default, for the preferred processor submodel. How this is done depends on the submodel. The m88100 processor does not reorder memory refer- ences and so always provides sequential consisten- cy. If you use `-✓-m✓m8✓88✓81✓10✓00✓0', GNU CC does not generate any special instructions for sequential consisten- cy. The order of memory references made by the m88110 processor does not always match the order of the instructions requesting those references. In par- ticular, a load instruction may execute before a preceding store instruction. Such reordering vio- lates sequential consistency of volatile memory references, when there are multiple processors. When you use `-✓-m✓m8✓88✓80✓00✓00✓0' or `-✓-m✓m8✓88✓81✓11✓10✓0', GNU CC gener- ates special instructions when appropriate, to force execution in the proper order. The extra code generated to guarantee consistency may affect the performance of your application. If you know that you can safely forgo this guarantee, you may use the option `-✓-m✓mn✓no✓o-✓-s✓se✓er✓ri✓ia✓al✓li✓iz✓ze✓e-✓-v✓vo✓ol✓la✓at✓ti✓il✓le✓e'. If you use the `-✓-m✓m8✓88✓81✓10✓00✓0' option but require sequen- tial consistency when running on the m88110 proces- sor, you should use `-✓-m✓ms✓se✓er✓ri✓ia✓al✓li✓iz✓ze✓e-✓-v✓vo✓ol✓la✓at✓ti✓il✓le✓e'. -✓-m✓ms✓sv✓vr✓r4✓4 -✓-m✓ms✓sv✓vr✓r3✓3 Turn on (`-✓-m✓ms✓sv✓vr✓r4✓4') or off (`-✓-m✓ms✓sv✓vr✓r3✓3') compiler ex- tensions related to System V release 4 (SVr4). This controls the following: +✓o Which variant of the assembler syntax to emit (which you can select independently using `-✓-m✓mv✓ve✓er✓rs✓si✓io✓on✓n-✓-0✓03✓3.✓.0✓00✓0'). +✓o `-✓-m✓ms✓sv✓vr✓r4✓4' makes the C preprocessor recognize `#✓#p✓pr✓ra✓ag✓g-✓- m✓ma✓a w✓we✓ea✓ak✓k' +✓o `-✓-m✓ms✓sv✓vr✓r4✓4' makes GCC issue additional declaration di- rectives used in SVr4. `-✓-m✓ms✓sv✓vr✓r3✓3' is the default for all m88K configurations except the SVr4 configuration. GNU Tools 1993/10/13 39 GCC(1) GNU Tools GCC(1) -✓-m✓mt✓tr✓ra✓ap✓p-✓-l✓la✓ar✓rg✓ge✓e-✓-s✓sh✓hi✓if✓ft✓t -✓-m✓mh✓ha✓an✓nd✓dl✓le✓e-✓-l✓la✓ar✓rg✓ge✓e-✓-s✓sh✓hi✓if✓ft✓t Include code to detect bit-shifts of more than 31 bits; respectively, trap such shifts or emit code to handle them properly. By default GCC makes no special provision for large bit shifts. -✓-m✓mu✓us✓se✓e-✓-d✓di✓iv✓v-✓-i✓in✓ns✓st✓tr✓ru✓uc✓ct✓ti✓io✓on✓n Very early models of the 88K architecture didn't have a divide instruction, so GCC avoids that in- struction by default. Use this option to specify that it's safe to use the divide instruction. -✓-m✓mv✓ve✓er✓rs✓si✓io✓on✓n-✓-0✓03✓3.✓.0✓00✓0 In the DG/UX configuration, there are two flavors of SVr4. This option modifies -✓-m✓ms✓sv✓vr✓r4✓4 to select whether the hybrid-COFF or real-ELF flavor is used. All other configurations ignore this option. -✓-m✓mw✓wa✓ar✓rn✓n-✓-p✓pa✓as✓ss✓se✓ed✓d-✓-s✓st✓tr✓ru✓uc✓ct✓ts✓s Warn when a function passes a struct as an argument or result. Structure-passing conventions have changed during the evolution of the C language, and are often the source of portability problems. By default, GCC issues no such warning. These options are defined for the IBM RS6000: -✓-m✓mf✓fp✓p-✓-i✓in✓n-✓-t✓to✓oc✓c -✓-m✓mn✓no✓o-✓-f✓fp✓p-✓-i✓in✓n-✓-t✓to✓oc✓c Control whether or not floating-point constants go in the Table of Contents (TOC), a table of all global variable and function addresses. By default GCC puts floating-point constants there; if the TOC overflows, `-✓-m✓mn✓no✓o-✓-f✓fp✓p-✓-i✓in✓n-✓-t✓to✓oc✓c' will reduce the size of the TOC, which may avoid the overflow. These `-✓-m✓m' options are defined for the IBM RT PC: -✓-m✓mi✓in✓n-✓-l✓li✓in✓ne✓e-✓-m✓mu✓ul✓l Use an in-line code sequence for integer multi- plies. This is the default. -✓-m✓mc✓ca✓al✓ll✓l-✓-l✓li✓ib✓b-✓-m✓mu✓ul✓l Call l✓lm✓mu✓ul✓l$✓$$✓$ for integer multiples. -✓-m✓mf✓fu✓ul✓ll✓l-✓-f✓fp✓p-✓-b✓bl✓lo✓oc✓ck✓ks✓s Generate full-size floating point data blocks, in- cluding the minimum amount of scratch space recom- mended by IBM. This is the default. GNU Tools 1993/10/13 40 GCC(1) GNU Tools GCC(1) -✓-m✓mm✓mi✓in✓ni✓im✓mu✓um✓m-✓-f✓fp✓p-✓-b✓bl✓lo✓oc✓ck✓ks✓s Do not include extra scratch space in floating point data blocks. This results in smaller code, but slower execution, since scratch space must be allocated dynamically. -✓-m✓mf✓fp✓p-✓-a✓ar✓rg✓g-✓-i✓in✓n-✓-f✓fp✓pr✓re✓eg✓gs✓s Use a calling sequence incompatible with the IBM calling convention in which floating point argu- ments are passed in floating point registers. Note that v✓va✓ar✓ra✓ar✓rg✓gs✓s.✓.h✓h and s✓st✓td✓da✓ar✓rg✓gs✓s.✓.h✓h will not work with floating point operands if this option is speci- fied. -✓-m✓mf✓fp✓p-✓-a✓ar✓rg✓g-✓-i✓in✓n-✓-g✓gr✓re✓eg✓gs✓s Use the normal calling convention for floating point arguments. This is the default. -✓-m✓mh✓hc✓c-✓-s✓st✓tr✓ru✓uc✓ct✓t-✓-r✓re✓et✓tu✓ur✓rn✓n Return structures of more than one word in memory, rather than in a register. This provides compati- bility with the MetaWare HighC (hc) compiler. Use `-✓-f✓fp✓pc✓cc✓c-✓-s✓st✓tr✓ru✓uc✓ct✓t-✓-r✓re✓et✓tu✓ur✓rn✓n' for compatibility with the Portable C Compiler (pcc). -✓-m✓mn✓no✓oh✓hc✓c-✓-s✓st✓tr✓ru✓uc✓ct✓t-✓-r✓re✓et✓tu✓ur✓rn✓n Return some structures of more than one word in registers, when convenient. This is the default. For compatibility with the IBM-supplied compilers, use either `-✓-f✓fp✓pc✓cc✓c-✓-s✓st✓tr✓ru✓uc✓ct✓t-✓-r✓re✓et✓tu✓ur✓rn✓n' or `-✓-m✓mh✓hc✓c-✓-s✓st✓tr✓ru✓uc✓ct✓t-✓-r✓re✓et✓tu✓ur✓rn✓n'. These `-✓-m✓m' options are defined for the MIPS family of com- puters: -✓-m✓mc✓cp✓pu✓u=✓=_✓c_✓p_✓u_✓-_✓t_✓y_✓p_✓e Assume the defaults for the machine type _✓c_✓p_✓u_✓-_✓t_✓y_✓p_✓e when scheduling instructions. The default _✓c_✓p_✓u_✓-_✓t_✓y_✓p_✓e is d✓de✓ef✓fa✓au✓ul✓lt✓t, which picks the longest cycles times for any of the machines, in order that the code run at reasonable rates on all MIPS cpu's. Other choices for _✓c_✓p_✓u_✓-_✓t_✓y_✓p_✓e are r✓r2✓20✓00✓00✓0, r✓r3✓30✓00✓00✓0, r✓r4✓40✓00✓00✓0, and r✓r6✓60✓00✓00✓0. While picking a specific _✓c_✓p_✓u_✓-_✓t_✓y_✓p_✓e will schedule things appropriately for that particular chip, the compiler will not generate any code that does not meet level 1 of the MIPS ISA (instruction set architecture) without the -✓-m✓mi✓ip✓ps✓s2✓2 or -✓-m✓mi✓ip✓ps✓s3✓3 switches being used. -✓-m✓mi✓ip✓ps✓s2✓2 Issue instructions from level 2 of the MIPS ISA (branch likely, square root instructions). The -✓-m✓mc✓cp✓pu✓u=✓=r✓r4✓40✓00✓00✓0 or -✓-m✓mc✓cp✓pu✓u=✓=r✓r6✓60✓00✓00✓0 switch must be used in conjunction with -✓-m✓mi✓ip✓ps✓s2✓2. GNU Tools 1993/10/13 41 GCC(1) GNU Tools GCC(1) -✓-m✓mi✓ip✓ps✓s3✓3 Issue instructions from level 3 of the MIPS ISA (64 bit instructions). The -✓-m✓mc✓cp✓pu✓u=✓=r✓r4✓40✓00✓00✓0 switch must be used in conjunction with -✓-m✓mi✓ip✓ps✓s2✓2. -✓-m✓mi✓in✓nt✓t6✓64✓4 -✓-m✓ml✓lo✓on✓ng✓g6✓64✓4 -✓-m✓ml✓lo✓on✓ng✓gl✓lo✓on✓ng✓g1✓12✓28✓8 These options don't work at present. -✓-m✓mm✓mi✓ip✓ps✓s-✓-a✓as✓s Generate code for the MIPS assembler, and invoke m✓mi✓ip✓ps✓s-✓-t✓tf✓fi✓il✓le✓e to add normal debug information. This is the default for all platforms except for the OSF/1 reference platform, using the OSF/rose object format. If any of the -✓-g✓gg✓gd✓db✓b, -✓-g✓gs✓st✓ta✓ab✓bs✓s, or -✓-g✓gs✓st✓ta✓ab✓bs✓s+✓+ switches are used, the m✓mi✓ip✓ps✓s-✓-t✓tf✓fi✓il✓le✓e program will en- capsulate the stabs within MIPS ECOFF. -✓-m✓mg✓ga✓as✓s Generate code for the GNU assembler. This is the default on the OSF/1 reference platform, using the OSF/rose object format. -✓-m✓mr✓rn✓na✓am✓me✓es✓s -✓-m✓mn✓no✓o-✓-r✓rn✓na✓am✓me✓es✓s The -✓-m✓mr✓rn✓na✓am✓me✓es✓s switch says to output code using the MIPS software names for the registers, instead of the hardware names (ie, a✓a0✓0 instead of $✓$4✓4). The GNU assembler does not support the -✓-m✓mr✓rn✓na✓am✓me✓es✓s switch, and the MIPS assembler will be instructed to run the MIPS C preprocessor over the source file. The -✓-m✓mn✓no✓o-✓-r✓rn✓na✓am✓me✓es✓s switch is default. -✓-m✓mg✓gp✓po✓op✓pt✓t -✓-m✓mn✓no✓o-✓-g✓gp✓po✓op✓pt✓t The -✓-m✓mg✓gp✓po✓op✓pt✓t switch says to write all of the data declarations before the instructions in the text section, to all the MIPS assembler to generate one word memory references instead of using two words for short global or static data items. This is on by default if optimization is selected. -✓-m✓ms✓st✓ta✓at✓ts✓s -✓-m✓mn✓no✓o-✓-s✓st✓ta✓at✓ts✓s For each non-inline function processed, the -✓-m✓ms✓st✓ta✓at✓ts✓s switch causes the compiler to emit one line to the standard error file to print statistics about the program (number of registers saved, stack size, etc.). GNU Tools 1993/10/13 42 GCC(1) GNU Tools GCC(1) -✓-m✓mm✓me✓em✓mc✓cp✓py✓y -✓-m✓mn✓no✓o-✓-m✓me✓em✓mc✓cp✓py✓y The -✓-m✓mm✓me✓em✓mc✓cp✓py✓y switch makes all block moves call the appropriate string function (m✓me✓em✓mc✓cp✓py✓y or b✓bc✓co✓op✓py✓y) in- stead of possibly generating inline code. -✓-m✓mm✓mi✓ip✓ps✓s-✓-t✓tf✓fi✓il✓le✓e -✓-m✓mn✓no✓o-✓-m✓mi✓ip✓ps✓s-✓-t✓tf✓fi✓il✓le✓e The -✓-m✓mn✓no✓o-✓-m✓mi✓ip✓ps✓s-✓-t✓tf✓fi✓il✓le✓e switch causes the compiler not postprocess the object file with the m✓mi✓ip✓ps✓s-✓-t✓tf✓fi✓il✓le✓e program, after the MIPS assembler has generated it to add debug support. If m✓mi✓ip✓ps✓s-✓-t✓tf✓fi✓il✓le✓e is not run, then no local variables will be available to the debugger. In addition, s✓st✓ta✓ag✓ge✓e2✓2 and s✓st✓ta✓ag✓ge✓e3✓3 objects will have the temporary file names passed to the assembler embedded in the object file, which means the objects will not compare the same. -✓-m✓ms✓so✓of✓ft✓t-✓-f✓fl✓lo✓oa✓at✓t Generate output containing library calls for float- ing point. _✓W_✓A_✓R_✓N_✓I_✓N_✓G_✓: the requisite libraries are not part of GNU CC. Normally the facilities of the machine's usual C compiler are used, but this can't be done directly in cross-compilation. You must make your own arrangements to provide suitable li- brary functions for cross-compilation. -✓-m✓mh✓ha✓ar✓rd✓d-✓-f✓fl✓lo✓oa✓at✓t Generate output containing floating point instruc- tions. This is the default if you use the unmodi- fied sources. -✓-m✓mf✓fp✓p6✓64✓4 Assume that the F✓FR✓R bit in the status word is on, and that there are 32 64-bit floating point regis- ters, instead of 32 32-bit floating point regis- ters. You must also specify the -✓-m✓mc✓cp✓pu✓u=✓=r✓r4✓40✓00✓00✓0 and -✓-m✓mi✓ip✓ps✓s3✓3 switches. -✓-m✓mf✓fp✓p3✓32✓2 Assume that there are 32 32-bit floating point reg- isters. This is the default. -✓-m✓ma✓ab✓bi✓ic✓ca✓al✓ll✓ls✓s -✓-m✓mn✓no✓o-✓-a✓ab✓bi✓ic✓ca✓al✓ll✓ls✓s Emit (or do not emit) the .✓.a✓ab✓bi✓ic✓ca✓al✓ll✓ls✓s, .✓.c✓cp✓pl✓lo✓oa✓ad✓d, and .✓.c✓cp✓pr✓re✓es✓st✓to✓or✓re✓e pseudo operations that some System V.4 ports use for position independent code. -✓-m✓mh✓ha✓al✓lf✓f-✓-p✓pi✓ic✓c -✓-m✓mn✓no✓o-✓-h✓ha✓al✓lf✓f-✓-p✓pi✓ic✓c The -✓-m✓mh✓ha✓al✓lf✓f-✓-p✓pi✓ic✓c switch says to put pointers to ex- GNU Tools 1993/10/13 43 GCC(1) GNU Tools GCC(1) tern references into the data section and load them up, rather than put the references in the text sec- tion. This option does not work at present. -✓-G✓G_✓n_✓u_✓m Put global and static items less than or equal to _✓n_✓u_✓m bytes into the small data or bss sections in- stead of the normal data or bss section. This al- lows the assembler to emit one word memory refer- ence instructions based on the global pointer (g✓gp✓p or $✓$2✓28✓8), instead of the normal two words used. By default, _✓n_✓u_✓m is 8 when the MIPS assembler is used, and 0 when the GNU assembler is used. The -✓-G✓G_✓n_✓u_✓m switch is also passed to the assembler and linker. All modules should be compiled with the same -✓-G✓G_✓n_✓u_✓m value. -✓-n✓no✓oc✓cp✓pp✓p Tell the MIPS assembler to not run it's preproces- sor over user assembler files (with a `.✓.s✓s' suffix) when assembling them. These `-✓-m✓m' options are defined for the Intel 80386 family of computers: -✓-m✓m4✓48✓86✓6 -✓-m✓mn✓no✓o-✓-4✓48✓86✓6 Control whether or not code is optimized for a 486 instead of an 386. Code generated for a 486 will run on a 386 and vice versa. -✓-m✓ms✓so✓of✓ft✓t-✓-f✓fl✓lo✓oa✓at✓t Generate output containing library calls for float- ing point. _✓W_✓a_✓r_✓n_✓i_✓n_✓g_✓: the requisite libraries are not part of GNU CC. Normally the facilities of the machine's usual C compiler are used, but this can't be done directly in cross-compilation. You must make your own arrangements to provide suitable li- brary functions for cross-compilation. On machines where a function returns floating point results in the 80387 register stack, some floating point opcodes may be emitted even if `-✓-m✓ms✓so✓of✓ft✓t-✓-f✓fl✓lo✓oa✓at✓t' is used. -✓-m✓mn✓no✓o-✓-f✓fp✓p-✓-r✓re✓et✓t-✓-i✓in✓n-✓-3✓38✓87✓7 Do not use the FPU registers for return values of functions. The usual calling convention has functions return values of types f✓fl✓lo✓oa✓at✓t and d✓do✓ou✓ub✓bl✓le✓e in an FPU regis- ter, even if there is no FPU. The idea is that the operating system should emulate an FPU. The option `-✓-m✓mn✓no✓o-✓-f✓fp✓p-✓-r✓re✓et✓t-✓-i✓in✓n-✓-3✓38✓87✓7' causes such values to be returned in ordinary CPU registers instead. These `-✓-m✓m' options are defined for the HPPA family of com- GNU Tools 1993/10/13 44 GCC(1) GNU Tools GCC(1) puters: -✓-m✓mp✓pa✓a-✓-r✓ri✓is✓sc✓c-✓-1✓1-✓-0✓0 Generate code for a PA 1.0 processor. -✓-m✓mp✓pa✓a-✓-r✓ri✓is✓sc✓c-✓-1✓1-✓-1✓1 Generate code for a PA 1.1 processor. -✓-m✓mk✓ke✓er✓rn✓ne✓el✓l Generate code which is suitable for use in kernels. Specifically, avoid a✓ad✓dd✓d instructions in which one of the arguments is the DP register; generate a✓ad✓dd✓di✓il✓l instructions instead. This avoids a rather serious bug in the HP-UX linker. -✓-m✓ms✓sh✓ha✓ar✓re✓ed✓d-✓-l✓li✓ib✓bs✓s Generate code that can be linked against HP-UX shared libraries. This option is not fully func- tion yet, and is not on by default for any PA tar- get. Using this option can cause incorrect code to be generated by the compiler. -✓-m✓mn✓no✓o-✓-s✓sh✓ha✓ar✓re✓ed✓d-✓-l✓li✓ib✓bs✓s Don't generate code that will be linked against shared libraries. This is the default for all PA targets. -✓-m✓ml✓lo✓on✓ng✓g-✓-c✓ca✓al✓ll✓ls✓s Generate code which allows calls to functions greater than 256K away from the caller when the caller and callee are in the same source file. Do not turn this option on unless code refuses to link with "branch out of range errors from the linker. -✓-m✓md✓di✓is✓sa✓ab✓bl✓le✓e-✓-f✓fp✓pr✓re✓eg✓gs✓s Prevent floating point registers from being used in any manner. This is necessary for compiling ker- nels which perform lazy context switching of float- ing point registers. If you use this option and attempt to perform floating point operations, the compiler will abort. -✓-m✓md✓di✓is✓sa✓ab✓bl✓le✓e-✓-i✓in✓nd✓de✓ex✓xi✓in✓ng✓g Prevent the compiler from using indexing address modes. This avoids some rather obscure problems when compiling MIG generated code under MACH. -✓-m✓mt✓tr✓ra✓ai✓il✓li✓in✓ng✓g-✓-c✓co✓ol✓lo✓on✓n Add a colon to the end of label definitions (for ELF assemblers). These `-✓-m✓m' options are defined for the Intel 80960 family of computers: GNU Tools 1993/10/13 45 GCC(1) GNU Tools GCC(1) -✓-m✓m_✓c_✓p_✓u_✓-_✓t_✓y_✓p_✓e Assume the defaults for the machine type _✓c_✓p_✓u_✓-_✓t_✓y_✓p_✓e for instruction and addressing-mode availability and alignment. The default _✓c_✓p_✓u_✓-_✓t_✓y_✓p_✓e is k✓kb✓b; other choices are k✓ka✓a, m✓mc✓c, c✓ca✓a, c✓cf✓f, s✓sa✓a, and s✓sb✓b. -✓-m✓mn✓nu✓um✓me✓er✓ri✓ic✓cs✓s -✓-m✓ms✓so✓of✓ft✓t-✓-f✓fl✓lo✓oa✓at✓t The -✓-m✓mn✓nu✓um✓me✓er✓ri✓ic✓cs✓s option indicates that the processor does support floating-point instructions. The -✓-m✓ms✓so✓of✓ft✓t-✓-f✓fl✓lo✓oa✓at✓t option indicates that floating-point support should not be assumed. -✓-m✓ml✓le✓ea✓af✓f-✓-p✓pr✓ro✓oc✓ce✓ed✓du✓ur✓re✓es✓s -✓-m✓mn✓no✓o-✓-l✓le✓ea✓af✓f-✓-p✓pr✓ro✓oc✓ce✓ed✓du✓ur✓re✓es✓s Do (or do not) attempt to alter leaf procedures to be callable with the _✓b_✓a_✓l instruction as well as _✓c_✓a_✓l_✓l. This will result in more efficient code for explicit calls when the _✓b_✓a_✓l instruction can be sub- stituted by the assembler or linker, but less effi- cient code in other cases, such as calls via func- tion pointers, or using a linker that doesn't sup- port this optimization. -✓-m✓mt✓ta✓ai✓il✓l-✓-c✓ca✓al✓ll✓l -✓-m✓mn✓no✓o-✓-t✓ta✓ai✓il✓l-✓-c✓ca✓al✓ll✓l Do (or do not) make additional attempts (beyond those of the machine-independent portions of the compiler) to optimize tail-recursive calls into branches. You may not want to do this because the detection of cases where this is not valid is not totally complete. The default is -✓-m✓mn✓no✓o-✓-t✓ta✓ai✓il✓l-✓-c✓ca✓al✓ll✓l. -✓-m✓mc✓co✓om✓mp✓pl✓le✓ex✓x-✓-a✓ad✓dd✓dr✓r -✓-m✓mn✓no✓o-✓-c✓co✓om✓mp✓pl✓le✓ex✓x-✓-a✓ad✓dd✓dr✓r Assume (or do not assume) that the use of a complex addressing mode is a win on this implementation of the i960. Complex addressing modes may not be worthwhile on the K-series, but they definitely are on the C-series. The default is currently -✓-m✓mc✓co✓om✓m-✓- p✓pl✓le✓ex✓x-✓-a✓ad✓dd✓dr✓r for all processors except the CB and CC. -✓-m✓mc✓co✓od✓de✓e-✓-a✓al✓li✓ig✓gn✓n -✓-m✓mn✓no✓o-✓-c✓co✓od✓de✓e-✓-a✓al✓li✓ig✓gn✓n Align code to 8-byte boundaries for faster fetching (or don't bother). Currently turned on by default for C-series implementations only. GNU Tools 1993/10/13 46 GCC(1) GNU Tools GCC(1) -✓-m✓mi✓ic✓c-✓-c✓co✓om✓mp✓pa✓at✓t -✓-m✓mi✓ic✓c2✓2.✓.0✓0-✓-c✓co✓om✓mp✓pa✓at✓t -✓-m✓mi✓ic✓c3✓3.✓.0✓0-✓-c✓co✓om✓mp✓pa✓at✓t Enable compatibility with iC960 v2.0 or v3.0. -✓-m✓ma✓as✓sm✓m-✓-c✓co✓om✓mp✓pa✓at✓t -✓-m✓mi✓in✓nt✓te✓el✓l-✓-a✓as✓sm✓m Enable compatibility with the iC960 assembler. -✓-m✓ms✓st✓tr✓ri✓ic✓ct✓t-✓-a✓al✓li✓ig✓gn✓n -✓-m✓mn✓no✓o-✓-s✓st✓tr✓ri✓ic✓ct✓t-✓-a✓al✓li✓ig✓gn✓n Do not permit (do permit) unaligned accesses. -✓-m✓mo✓ol✓ld✓d-✓-a✓al✓li✓ig✓gn✓n Enable structure-alignment compatibility with In- tel's gcc release version 1.3 (based on gcc 1.37). Currently this is buggy in that #✓#p✓pr✓ra✓ag✓gm✓ma✓a a✓al✓li✓ig✓gn✓n 1✓1 is always assumed as well, and cannot be turned off. These `-✓-m✓m' options are defined for the DEC Alpha implemen- tations: -✓-m✓mn✓no✓o-✓-s✓so✓of✓ft✓t-✓-f✓fl✓lo✓oa✓at✓t -✓-m✓ms✓so✓of✓ft✓t-✓-f✓fl✓lo✓oa✓at✓t Use (do not use) the hardware floating-point in- structions for floating-point operations. When -✓-m✓ms✓so✓of✓ft✓t-✓-f✓fl✓lo✓oa✓at✓t is specified, functions in `l✓li✓ib✓bg✓gc✓cc✓c1✓1.✓.c✓c' will be used to perform floating-point operations. Unless they are replaced by routines that emulate the floating-point operations, or compiled in such a way as to call such emulations routines, these routines will issue floating-point operations. If you are compiling for an Alpha without floating- point operations, you must ensure that the library is built so as not to call them. Note that Alpha implementations without floating- point operations are required to have floating- point registers. -✓-m✓mf✓fp✓p-✓-r✓re✓eg✓g -✓-m✓mn✓no✓o-✓-f✓fp✓p-✓-r✓re✓eg✓gs✓s Generate code that uses (does not use) the float- ing-point register set. -✓-m✓mn✓no✓o-✓-f✓fp✓p-✓-r✓re✓eg✓gs✓s implies -✓-m✓ms✓so✓of✓ft✓t-✓-f✓fl✓lo✓oa✓at✓t. If the floating-point register set is not used, floating point operands are passed in integer registers as if they were integers and floating-point results are passed in $0 instead of GNU Tools 1993/10/13 47 GCC(1) GNU Tools GCC(1) $f0. This is a non-standard calling sequence, so any function with a floating-point argument or re- turn value called by code compiled with -✓-m✓mn✓no✓o-✓-f✓fp✓p-✓- r✓re✓eg✓gs✓s must also be compiled with that option. A typical use of this option is building a kernel that does not use, and hence need not save and re- store, any floating-point registers. These additional options are available on System V Release 4 for compatibility with other compilers on those systems: -✓-G✓G On SVr4 systems, g✓gc✓cc✓c accepts the option `-✓-G✓G' (and passes it to the system linker), for compatibility with other compilers. However, we suggest you use `-✓-s✓sy✓ym✓mb✓bo✓ol✓li✓ic✓c' or `-✓-s✓sh✓ha✓ar✓re✓ed✓d' as appropriate, instead of supplying linker options on the g✓gc✓cc✓c command line. -✓-Q✓Qy✓y Identify the versions of each tool used by the com- piler, in a .✓.i✓id✓de✓en✓nt✓t assembler directive in the out- put. -✓-Q✓Qn✓n Refrain from adding .✓.i✓id✓de✓en✓nt✓t directives to the output file (this is the default). -✓-Y✓YP✓P,✓,_✓d_✓i_✓r_✓s Search the directories _✓d_✓i_✓r_✓s, and no others, for li- braries specified with `-✓-l✓l'. You can separate di- rectory entries in _✓d_✓i_✓r_✓s from one another with colons. -✓-Y✓Ym✓m,✓,_✓d_✓i_✓r Look in the directory _✓d_✓i_✓r to find the M4 preproces- sor. The assembler uses this option. C✓CO✓OD✓DE✓E G✓GE✓EN✓NE✓ER✓RA✓AT✓TI✓IO✓ON✓N O✓OP✓PT✓TI✓IO✓ON✓NS✓S These machine-independent options control the interface conventions used in code generation. Most of them begin with `-f'. These options have both positive and negative forms; the negative form of `-✓-f✓ff✓fo✓oo✓o' would be `-✓-f✓fn✓no✓o-✓-f✓fo✓oo✓o'. In the table below, only one of the forms is listed--the one which is not the default. You can figure out the other form by either removing `n✓no✓o-✓-' or adding it. -✓-f✓fn✓no✓on✓nn✓nu✓ul✓ll✓l-✓-o✓ob✓bj✓je✓ec✓ct✓ts✓s Assume that objects reached through references are not null (C++ only). Normally, GNU C++ makes conservative assumptions about objects reached through references. For ex- ample, the compiler must check that a✓a is not null in code like the following: GNU Tools 1993/10/13 48 GCC(1) GNU Tools GCC(1) obj &a = g (); a.f (2); Checking that references of this sort have non-null values requires extra code, however, and it is un- necessary for many programs. You can use `-✓-f✓fn✓no✓on✓nn✓nu✓ul✓ll✓l-✓-o✓ob✓bj✓je✓ec✓ct✓ts✓s' to omit the checks for null, if your program doesn't require checking. -✓-f✓fp✓pc✓cc✓c-✓-s✓st✓tr✓ru✓uc✓ct✓t-✓-r✓re✓et✓tu✓ur✓rn✓n Use the same convention for returning s✓st✓tr✓ru✓uc✓ct✓t and u✓un✓ni✓io✓on✓n values that is used by the usual C compiler on your system. This convention is less efficient for small structures, and on many machines it fails to be reentrant; but it has the advantage of allow- ing intercallability between GCC-compiled code and PCC-compiled code. -✓-f✓fr✓re✓eg✓g-✓-s✓st✓tr✓ru✓uc✓ct✓t-✓-r✓re✓et✓tu✓ur✓rn✓n Use the convention that s✓st✓tr✓ru✓uc✓ct✓t and u✓un✓ni✓io✓on✓n values are returned in registers when possible. This is more efficient for small structures than -✓-f✓fp✓pc✓cc✓c-✓-s✓st✓tr✓ru✓uc✓ct✓t-✓-r✓re✓et✓tu✓ur✓rn✓n. If you specify neither -✓-f✓fp✓pc✓cc✓c-✓-s✓st✓tr✓ru✓uc✓ct✓t-✓-r✓re✓et✓tu✓ur✓rn✓n nor -✓-f✓fr✓re✓eg✓g-✓-s✓st✓tr✓ru✓uc✓ct✓t-✓-r✓re✓et✓tu✓ur✓rn✓n, GNU CC defaults to whichever convention is standard for the target. If there is no standard convention, GNU CC defaults to -✓-f✓fp✓pc✓cc✓c-✓-s✓st✓tr✓ru✓uc✓ct✓t-✓-r✓re✓et✓tu✓ur✓rn✓n. -✓-f✓fs✓sh✓ho✓or✓rt✓t-✓-e✓en✓nu✓um✓ms✓s Allocate to an e✓en✓nu✓um✓m type only as many bytes as it needs for the declared range of possible values. Specifically, the e✓en✓nu✓um✓m type will be equivalent to the smallest integer type which has enough room. -✓-f✓fs✓sh✓ho✓or✓rt✓t-✓-d✓do✓ou✓ub✓bl✓le✓e Use the same size for d✓do✓ou✓ub✓bl✓le✓e as for f✓fl✓lo✓oa✓at✓t . -✓-f✓fs✓sh✓ha✓ar✓re✓ed✓d-✓-d✓da✓at✓ta✓a Requests that the data and non-c✓co✓on✓ns✓st✓t variables of this compilation be shared data rather than private data. The distinction makes sense only on certain operating systems, where shared data is shared be- tween processes running the same program, while private data exists in one copy per process. -✓-f✓fn✓no✓o-✓-c✓co✓om✓mm✓mo✓on✓n Allocate even uninitialized global variables in the bss section of the object file, rather than gener- ating them as common blocks. This has the effect that if the same variable is declared (without e✓ex✓x-✓- t✓te✓er✓rn✓n) in two different compilations, you will get an error when you link them. The only reason this might be useful is if you wish to verify that the GNU Tools 1993/10/13 49 GCC(1) GNU Tools GCC(1) program will work on other systems which always work this way. -✓-f✓fn✓no✓o-✓-i✓id✓de✓en✓nt✓t Ignore the `#✓#i✓id✓de✓en✓nt✓t' directive. -✓-f✓fn✓no✓o-✓-g✓gn✓nu✓u-✓-l✓li✓in✓nk✓ke✓er✓r Do not output global initializations (such as C++ constructors and destructors) in the form used by the GNU linker (on systems where the GNU linker is the standard method of handling them). Use this option when you want to use a non-GNU linker, which also requires using the c✓co✓ol✓ll✓le✓ec✓ct✓t2✓2 program to make sure the system linker includes constructors and destructors. (c✓co✓ol✓ll✓le✓ec✓ct✓t2✓2 is included in the GNU CC distribution.) For systems which _✓m_✓u_✓s_✓t use c✓co✓ol✓l-✓- l✓le✓ec✓ct✓t2✓2, the compiler driver g✓gc✓cc✓c is configured to do this automatically. -✓-f✓fi✓in✓nh✓hi✓ib✓bi✓it✓t-✓-s✓si✓iz✓ze✓e-✓-d✓di✓ir✓re✓ec✓ct✓ti✓iv✓ve✓e Don't output a .✓.s✓si✓iz✓ze✓e assembler directive, or any- thing else that would cause trouble if the function is split in the middle, and the two halves are placed at locations far apart in memory. This op- tion is used when compiling `c✓cr✓rt✓ts✓st✓tu✓uf✓ff✓f.✓.c✓c'; you should not need to use it for anything else. -✓-f✓fv✓ve✓er✓rb✓bo✓os✓se✓e-✓-a✓as✓sm✓m Put extra commentary information in the generated assembly code to make it more readable. This op- tion is generally only of use to those who actually need to read the generated assembly code (perhaps while debugging the compiler itself). -✓-f✓fv✓vo✓ol✓la✓at✓ti✓il✓le✓e Consider all memory references through pointers to be volatile. -✓-f✓fv✓vo✓ol✓la✓at✓ti✓il✓le✓e-✓-g✓gl✓lo✓ob✓ba✓al✓l Consider all memory references to extern and global data items to be volatile. -✓-f✓fp✓pi✓ic✓c If supported for the target machines, generate po- sition-independent code, suitable for use in a shared library. -✓-f✓fP✓PI✓IC✓C If supported for the target machine, emit position- independent code, suitable for dynamic linking, even if branches need large displacements. -✓-f✓ff✓fi✓ix✓xe✓ed✓d-✓-_✓r_✓e_✓g Treat the register named _✓r_✓e_✓g as a fixed register; generated code should never refer to it (except perhaps as a stack pointer, frame pointer or in GNU Tools 1993/10/13 50 GCC(1) GNU Tools GCC(1) some other fixed role). _✓r_✓e_✓g must be the name of a register. The register names accepted are machine-specific and are defined in the R✓RE✓EG✓GI✓IS✓ST✓TE✓ER✓R_✓_N✓NA✓AM✓ME✓ES✓S macro in the machine descrip- tion macro file. This flag does not have a negative form, because it specifies a three-way choice. -✓-f✓fc✓ca✓al✓ll✓l-✓-u✓us✓se✓ed✓d-✓-_✓r_✓e_✓g Treat the register named _✓r_✓e_✓g as an allocatable reg- ister that is clobbered by function calls. It may be allocated for temporaries or variables that do not live across a call. Functions compiled this way will not save and restore the register _✓r_✓e_✓g. Use of this flag for a register that has a fixed pervasive role in the machine's execution model, such as the stack pointer or frame pointer, will produce disastrous results. This flag does not have a negative form, because it specifies a three-way choice. -✓-f✓fc✓ca✓al✓ll✓l-✓-s✓sa✓av✓ve✓ed✓d-✓-_✓r_✓e_✓g Treat the register named _✓r_✓e_✓g as an allocatable reg- ister saved by functions. It may be allocated even for temporaries or variables that live across a call. Functions compiled this way will save and restore the register _✓r_✓e_✓g if they use it. Use of this flag for a register that has a fixed pervasive role in the machine's execution model, such as the stack pointer or frame pointer, will produce disastrous results. A different sort of disaster will result from the use of this flag for a register in which function values may be returned. This flag does not have a negative form, because it specifies a three-way choice. P✓PR✓RA✓AG✓GM✓MA✓AS✓S Two `#✓#p✓pr✓ra✓ag✓gm✓ma✓a' directives are supported for GNU C++, to permit using the same header file for two purposes: as a definition of interfaces to a given object class, and as the full definition of the contents of that object class. #✓#p✓pr✓ra✓ag✓gm✓ma✓a i✓in✓nt✓te✓er✓rf✓fa✓ac✓ce✓e (C++ only.) Use this directive in header files that define object classes, to save space in most of the object files that use those classes. Nor- GNU Tools 1993/10/13 51 GCC(1) GNU Tools GCC(1) mally, local copies of certain information (backup copies of inline member functions, debugging infor- mation, and the internal tables that implement vir- tual functions) must be kept in each object file that includes class definitions. You can use this pragma to avoid such duplication. When a header file containing `#✓#p✓pr✓ra✓ag✓gm✓ma✓a i✓in✓nt✓te✓er✓rf✓fa✓ac✓ce✓e' is included in a compilation, this auxiliary information will not be generated (unless the main input source file it- self uses `#✓#p✓pr✓ra✓ag✓gm✓ma✓a i✓im✓mp✓pl✓le✓em✓me✓en✓nt✓ta✓at✓ti✓io✓on✓n'). Instead, the object files will contain references to be resolved at link time. #✓#p✓pr✓ra✓ag✓gm✓ma✓a i✓im✓mp✓pl✓le✓em✓me✓en✓nt✓ta✓at✓ti✓io✓on✓n #✓#p✓pr✓ra✓ag✓gm✓ma✓a i✓im✓mp✓pl✓le✓em✓me✓en✓nt✓ta✓at✓ti✓io✓on✓n "✓"_✓o_✓b_✓j_✓e_✓c_✓t_✓s.✓.h✓h"✓" (C++ only.) Use this pragma in a main input file, when you want full output from included header files to be generated (and made globally visible). The included header file, in turn, should use `#✓#p✓pr✓ra✓ag✓gm✓ma✓a i✓in✓nt✓te✓er✓rf✓fa✓ac✓ce✓e'. Backup copies of inline mem- ber functions, debugging information, and the in- ternal tables used to implement virtual functions are all generated in implementation files. If you use `#✓#p✓pr✓ra✓ag✓gm✓ma✓a i✓im✓mp✓pl✓le✓em✓me✓en✓nt✓ta✓at✓ti✓io✓on✓n' with no argu- ment, it applies to an include file with the same basename as your source file; for example, in `a✓al✓ll✓lc✓cl✓la✓as✓ss✓s.✓.c✓cc✓c', `#✓#p✓pr✓ra✓ag✓gm✓ma✓a i✓im✓mp✓pl✓le✓em✓me✓en✓nt✓ta✓at✓ti✓io✓on✓n' by itself is equivalent to `#✓#p✓pr✓ra✓ag✓gm✓ma✓a i✓im✓mp✓pl✓le✓em✓me✓en✓nt✓ta✓at✓ti✓io✓on✓n "✓"a✓al✓ll✓lc✓cl✓la✓as✓ss✓s.✓.h✓h"✓"'. Use the string argument if you want a single implementation file to include code from multiple header files. There is no way to split up the contents of a sin- gle header file into multiple implementation files. F✓FI✓IL✓LE✓ES✓S file.c C source file file.h C header (preprocessor) file file.i preprocessed C source file file.C C++ source file file.cc C++ source file file.cxx C++ source file file.m Objective-C source file file.s assembly language file file.o object file a.out link edited output _✓T_✓M_✓P_✓D_✓I_✓R/cc* temporary files _✓L_✓I_✓B_✓D_✓I_✓R/cpp preprocessor _✓L_✓I_✓B_✓D_✓I_✓R/cc1 compiler for C _✓L_✓I_✓B_✓D_✓I_✓R/cc1plus compiler for C++ _✓L_✓I_✓B_✓D_✓I_✓R/collect linker front end needed on some machines _✓L_✓I_✓B_✓D_✓I_✓R/libgcc.a GCC subroutine library GNU Tools 1993/10/13 52 GCC(1) GNU Tools GCC(1) /lib/crt[01n].o start-up routine _✓L_✓I_✓B_✓D_✓I_✓R/ccrt0 additional start-up routine for C++ /lib/libc.a standard C library, see _✓i_✓n_✓t_✓r_✓o(3) /usr/include standard directory for #✓#i✓in✓nc✓cl✓lu✓ud✓de✓e files _✓L_✓I_✓B_✓D_✓I_✓R/include standard gcc directory for #✓#i✓in✓nc✓cl✓lu✓ud✓de✓e files _✓L_✓I_✓B_✓D_✓I_✓R/g++-include additional g++ directory for #✓#i✓in✓nc✓cl✓lu✓ud✓de✓e _✓L_✓I_✓B_✓D_✓I_✓R is usually /✓/u✓us✓sr✓r/✓/l✓lo✓oc✓ca✓al✓l/✓/l✓li✓ib✓b/✓/_✓m_✓a_✓c_✓h_✓i_✓n_✓e/_✓v_✓e_✓r_✓s_✓i_✓o_✓n. _✓T_✓M_✓P_✓D_✓I_✓R comes from the environment variable T✓TM✓MP✓PD✓DI✓IR✓R (default /✓/u✓us✓sr✓r/✓/t✓tm✓mp✓p if available, else /✓/t✓tm✓mp✓p). S✓SE✓EE✓E A✓AL✓LS✓SO✓O cpp(1), as(1), ld(1), gdb(1), adb(1), dbx(1), sdb(1). `g✓gc✓cc✓c', `c✓cp✓pp✓p', `a✓as✓s', `l✓ld✓d', and `g✓gd✓db✓b' entries in i✓in✓nf✓fo✓o. _✓U_✓s_✓i_✓n_✓g _✓a_✓n_✓d _✓P_✓o_✓r_✓t_✓i_✓n_✓g _✓G_✓N_✓U _✓C_✓C _✓(_✓f_✓o_✓r _✓v_✓e_✓r_✓s_✓i_✓o_✓n _✓2_✓._✓0_✓), Richard M. Stallman; _✓T_✓h_✓e _✓C _✓P_✓r_✓e_✓p_✓r_✓o_✓c_✓e_✓s_✓s_✓o_✓r, Richard M. Stallman; _✓D_✓e_✓b_✓u_✓g_✓- _✓g_✓i_✓n_✓g _✓w_✓i_✓t_✓h _✓G_✓D_✓B_✓: _✓t_✓h_✓e _✓G_✓N_✓U _✓S_✓o_✓u_✓r_✓c_✓e_✓-_✓L_✓e_✓v_✓e_✓l _✓D_✓e_✓b_✓u_✓g_✓g_✓e_✓r, Richard M. Stallman and Roland H. Pesch; _✓U_✓s_✓i_✓n_✓g _✓a_✓s_✓: _✓t_✓h_✓e _✓G_✓N_✓U _✓A_✓s_✓s_✓e_✓m_✓b_✓l_✓e_✓r, Dean Elsner, Jay Fenlason & friends; _✓l_✓d_✓: _✓t_✓h_✓e _✓G_✓N_✓U _✓l_✓i_✓n_✓k_✓e_✓r, Steve Chamberlain and Roland Pesch. B✓BU✓UG✓GS✓S For instructions on reporting bugs, see the GCC manual. C✓CO✓OP✓PY✓YI✓IN✓NG✓G Copyright 1991, 1992, 1993 Free Software Foundation, Inc. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified ver- sions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above con- ditions for modified versions, except that this permission notice may be included in translations approved by the Free Software Foundation instead of in the original En- glish. A✓AU✓UT✓TH✓HO✓OR✓RS✓S See the GNU CC Manual for the contributors to GNU CC. GNU Tools 1993/10/13 53