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GNU Info File | 1992-09-10 | 49.5 KB | 1,137 lines

This is Info file gcc.info, produced by Makeinfo-1.47 from the input file gcc.texinfo. This file documents the use and the internals of the GNU compiler. Copyright (C) 1988, 1989, 1990 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 versions of this manual under the conditions for verbatim copying, provided also that the sections entitled "GNU General Public License" and "Protect Your Freedom--Fight `Look And Feel'" are included exactly as in the original, and 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 conditions for modified versions, except that the sections entitled "GNU General Public License" and "Protect Your Freedom--Fight `Look And Feel'" and this permission notice may be included in translations approved by the Free Software Foundation instead of in the original English. File: gcc.info, Node: Addressing Modes, Next: Delayed Branch, Prev: Library Calls, Up: Machine Macros Addressing Modes ================ `HAVE_POST_INCREMENT' Define this macro if the machine supports post-increment addressing. `HAVE_PRE_INCREMENT' `HAVE_POST_DECREMENT' `HAVE_PRE_DECREMENT' Similar for other kinds of addressing. `CONSTANT_ADDRESS_P (X)' A C expression that is 1 if the RTX X is a constant whose value is an integer. This includes integers whose values are not explicitly known, such as `symbol_ref' and `label_ref' expressions and `const' arithmetic expressions. On most machines, this can be defined as `CONSTANT_P (X)', but a few machines are more restrictive in which constant addresses are supported. `MAX_REGS_PER_ADDRESS' A number, the maximum number of registers that can appear in a valid memory address. Note that it is up to you to specify a value equal to the maximum number that `go_if_legitimate_address' would ever accept. `GO_IF_LEGITIMATE_ADDRESS (MODE, X, LABEL)' A C compound statement with a conditional `goto LABEL;' executed if X (an RTX) is a legitimate memory address on the target machine for a memory operand of mode MODE. It usually pays to define several simpler macros to serve as subroutines for this one. Otherwise it may be too complicated to understand. This macro must exist in two variants: a strict variant and a non-strict one. The strict variant is used in the reload pass. It must be defined so that any pseudo-register that has not been allocated a hard register is considered a memory reference. In contexts where some kind of register is required, a pseudo-register with no hard register must be rejected. The non-strict variant is used in other passes. It must be defined to accept all pseudo-registers in every context where some kind of register is required. Compiler source files that want to use the strict variant of this macro define the macro `REG_OK_STRICT'. You should use an `#ifdef REG_OK_STRICT' conditional to define the strict variant in that case and the non-strict variant otherwise. Typically among the subroutines used to define `GO_IF_LEGITIMATE_ADDRESS' are subroutines to check for acceptable registers for various purposes (one for base registers, one for index registers, and so on). Then only these subroutine macros need have two variants; the higher levels of macros may be the same whether strict or not. Normally, constant addresses which are the sum of a `symbol_ref' and an integer are stored inside a `const' RTX to mark them as constant. Therefore, there is no need to recognize such sums as legitimate addresses. Usually `PRINT_OPERAND_ADDRESS' is not prepared to handle constant sums that are not marked with `const'. It assumes that a naked `plus' indicates indexing. If so, then you *must* reject such naked constant sums as illegitimate addresses, so that none of them will be given to `PRINT_OPERAND_ADDRESS'. `REG_OK_FOR_BASE_P (X)' A C expression that is nonzero if X (assumed to be a `reg' RTX) is valid for use as a base register. For hard registers, it should always accept those which the hardware permits and reject the others. Whether the macro accepts or rejects pseudo registers must be controlled by `REG_OK_STRICT' as described above. This usually requires two variant definitions, of which `REG_OK_STRICT' controls the one actually used. `REG_OK_FOR_INDEX_P (X)' A C expression that is nonzero if X (assumed to be a `reg' RTX) is valid for use as an index register. The difference between an index register and a base register is that the index register may be scaled. If an address involves the sum of two registers, neither one of them scaled, then either one may be labeled the "base" and the other the "index"; but whichever labeling is used must fit the machine's constraints of which registers may serve in each capacity. The compiler will try both labelings, looking for one that is valid, and will reload one or both registers only if neither labeling works. `LEGITIMIZE_ADDRESS (X, OLDX, MODE, WIN)' A C compound statement that attempts to replace X with a valid memory address for an operand of mode MODE. WIN will be a C statement label elsewhere in the code; the macro definition may use GO_IF_LEGITIMATE_ADDRESS (MODE, X, WIN); to avoid further processing if the address has become legitimate. X will always be the result of a call to `break_out_memory_refs', and OLDX will be the operand that was given to that function to produce X. The code generated by this macro should not alter the substructure of X. If it transforms X into a more legitimate form, it should assign X (which will always be a C variable) a new value. It is not necessary for this macro to come up with a legitimate address. The compiler has standard ways of doing so in all cases. In fact, it is safe for this macro to do nothing. But often a machine-dependent strategy can generate better code. `GO_IF_MODE_DEPENDENT_ADDRESS (ADDR, LABEL)' A C statement or compound statement with a conditional `goto LABEL;' executed if memory address X (an RTX) can have different meanings depending on the machine mode of the memory reference it is used for. Autoincrement and autodecrement addresses typically have mode-dependent effects because the amount of the increment or decrement is the size of the operand being addressed. Some machines have other mode-dependent addresses. Many RISC machines have no mode-dependent addresses. You may assume that ADDR is a valid address for the machine. `LEGITIMATE_CONSTANT_P (X)' A C expression that is nonzero if X is a legitimate constant for an immediate operand on the target machine. You can assume that either X is a `const_double' or it satisfies `CONSTANT_P', so you need not check these things. In fact, `1' is a suitable definition for this macro on machines where any `const_double' is valid and anything `CONSTANT_P' is valid. File: gcc.info, Node: Delayed Branch, Next: Condition Code, Prev: Addressing Modes, Up: Machine Macros Parameters for Delayed Branch Optimization ========================================== `HAVE_DELAYED_BRANCH' Define this macro if the target machine has delayed branches, that is, a branch does not take effect immediately, and the actual branch instruction may be followed by one or more instructions that will be issued before the PC is actually changed. If defined, this allows a special scheduling pass to be run after the second jump optimization to attempt to reorder instructions to exploit this. Defining this macro also requires the definition of certain other macros described below. `DBR_SLOTS_AFTER (INSN)' This macro must be defined if `HAVE_DELAYED_BRANCH' is defined. Its definition should be a C expression returning the number of available delay slots following the instruction(s) output by the pattern for INSN. The definition of "slot" is machine-dependent, and may denote instructions, bytes, or whatever. `DBR_INSN_SLOTS (INSN)' This macro must be defined if `HAVE_DELAYED_BRANCH' is defined. It should be a C expression returning the number of slots (typically the number of machine instructions) consumed by INSN. You may assume that INSN is truly an insn, not a note, label, barrier, dispatch table, `use', or `clobber'. `DBR_INSN_ELIGIBLE_P (INSN, DINSN)' A C expression whose value is non-zero if it is legitimate to put INSN in the delay slot following DINSN. You do not need to take account of data flow considerations in the definition of this macro, because the delayed branch optimizer always does that. This macro is needed only when certain insns may not be placed in certain delay slots for reasons not evident from the RTL expressions themselves. If there are no such problems, you don't need to define this macro. You may assume that INSN is truly an insn, not a note, label, barrier, dispatch table, `use', or `clobber'. You may assume that DINSN is a jump insn with a delay slot. `DBR_OUTPUT_SEQEND(FILE)' A C statement, to be executed after all slot-filler instructions have been output. If necessary, call `dbr_sequence_length' to determine the number of slots filled in a sequence (zero if not currently outputting a sequence), to decide how many no-ops to output, or whatever. Don't define this macro if it has nothing to do, but it is helpful in reading assembly output if the extent of the delay sequence is made explicit (e.g. with white space). Note that output routines for instructions with delay slots must be prepared to deal with not being output as part of a sequence (i.e. when the scheduling pass is not run, or when no slot fillers could be found.) The variable `final_sequence' is null when not processing a sequence, otherwise it contains the `sequence' rtx being output. File: gcc.info, Node: Condition Code, Next: Cross-compilation, Prev: Delayed Branch, Up: Machine Macros Condition Code Information ========================== The file `conditions.h' defines a variable `cc_status' to describe how the condition code was computed (in case the interpretation of the condition code depends on the instruction that it was set by). This variable contains the RTL expressions on which the condition code is currently based, and several standard flags. Sometimes additional machine-specific flags must be defined in the machine description header file. It can also add additional machine-specific information by defining `CC_STATUS_MDEP'. `CC_STATUS_MDEP' C code for a data type which is used for declaring the `mdep' component of `cc_status'. It defaults to `int'. `CC_STATUS_MDEP_INIT' A C expression to initialize the `mdep' field to "empty". The default definition does nothing, since most machines don't use the field anyway. If you want to use the field, you should probably define this macro to initialize it. `NOTICE_UPDATE_CC (EXP, INSN)' A C compound statement to set the components of `cc_status' appropriately for an insn INSN whose body is EXP. It is this macro's responsibility to recognize insns that set the condition code as a byproduct of other activity as well as those that explicitly set `(cc0)'. If there are insn that do not set the condition code but do alter other machine registers, this macro must check to see whether they invalidate the expressions that the condition code is recorded as reflecting. For example, on the 68000, insns that store in address registers do not set the condition code, which means that usually `NOTICE_UPDATE_CC' can leave `cc_status' unaltered for such insns. But suppose that the previous insn set the condition code based on location `a4@(102)' and the current insn stores a new value in `a4'. Although the condition code is not changed by this, it will no longer be true that it reflects the contents of `a4@(102)'. Therefore, `NOTICE_UPDATE_CC' must alter `cc_status' in this case to say that nothing is known about the condition code value. The definition of `NOTICE_UPDATE_CC' must be prepared to deal with the results of peephole optimization: insns whose patterns are `parallel' RTXs containing various `reg', `mem' or constants which are just the operands. The RTL structure of these insns is not sufficient to indicate what the insns actually do. What `NOTICE_UPDATE_CC' should do when it sees one is just to run `CC_STATUS_INIT'. File: gcc.info, Node: Cross-compilation, Next: Misc, Prev: Condition Code, Up: Machine Macros Cross Compilation and Floating-Point Format =========================================== While all modern machines use 2's complement representation for integers, there are a variety of representations for floating point numbers. This means that in a cross-compiler the representation of floating point numbers in the compiled program may be different from that used in the machine doing the compilation. Because different representation systems may offer different amounts of range and precision, the cross compiler cannot safely use the host machine's floating point arithmetic. Therefore, floating point constants must be represented in the target machine's format. This means that the cross compiler cannot use `atof' to parse a floating point constant; it must have its own special routine to use instead. Also, constant folding must emulate the target machine's arithmetic (or must not be done at all). The macros in the following table should be defined only if you are cross compiling between different floating point formats. Otherwise, don't define them. Then default definitions will be set up which use `double' as the data type, `==' to test for equality, etc. You don't need to worry about how many times you use an operand of any of these macros. The compiler never uses operands which have side effects. `REAL_VALUE_TYPE' A macro for the C data type to be used to hold a floating point value in the target machine's format. Typically this would be a `struct' containing an array of `int'. `REAL_VALUES_EQUAL (X, Y)' A macro for a C expression which compares for equality the two values, X and Y, both of type `REAL_VALUE_TYPE'. `REAL_VALUES_LESS (X, Y)' A macro for a C expression which tests whether X is less than Y, both values being of type `REAL_VALUE_TYPE' and interpreted as floating point numbers in the target machine's representation. `REAL_VALUE_LDEXP (X, SCALE)' A macro for a C expression which performs the standard library function `ldexp', but using the target machine's floating point representation. Both X and the value of the expression have type `REAL_VALUE_TYPE'. The second argument, SCALE, is an integer. `REAL_VALUE_ATOF (STRING)' A macro for a C expression which converts STRING, an expression of type `char *', into a floating point number in the target machine's representation. The value has type `REAL_VALUE_TYPE'. Define the following additional macros if you want to make floating point constant folding work while cross compiling. If you don't define them, cross compilation is still possible, but constant folding will not happen for floating point values. `REAL_ARITHMETIC (OUTPUT, CODE, X, Y)' A macro for a C statement which calculates an arithmetic operation of the two floating point values X and Y, both of type `REAL_VALUE_TYPE' in the target machine's representation, to produce a result of the same type and representation which is stored in OUTPUT (which will be a variable). The operation to be performed is specified by CODE, a tree code which will always be one of the following: `PLUS_EXPR', `MINUS_EXPR', `MULT_EXPR', `RDIV_EXPR', `MAX_EXPR', `MIN_EXPR'. The expansion of this macro is responsible for checking for overflow. If overflow happens, the macro expansion should execute the statement `return 0;', which indicates the inability to perform the arithmetic operation requested. `REAL_VALUE_NEGATE (X)' A macro for a C expression which returns the negative of the floating point value X. Both X and the value of the expression have type `REAL_VALUE_TYPE' and are in the target machine's floating point representation. There is no way for this macro to report overflow, since overflow can't happen in the negation operation. `REAL_VALUE_TO_INT (LOW, HIGH, X)' A macro for a C expression which converts a floating point value X into a double-precision integer which is then stored into LOW and HIGH, two variables of type INT. `REAL_VALUE_FROM_INT (X, LOW, HIGH)' A macro for a C expression which converts a double-precision integer found in LOW and HIGH, two variables of type INT, into a floating point value which is then stored into X. File: gcc.info, Node: Misc, Next: Assembler Format, Prev: Cross-compilation, Up: Machine Macros Miscellaneous Parameters ======================== `CASE_VECTOR_MODE' An alias for a machine mode name. This is the machine mode that elements of a jump-table should have. `CASE_VECTOR_PC_RELATIVE' Define this macro if jump-tables should contain relative addresses. `CASE_DROPS_THROUGH' Define this if control falls through a `case' insn when the index value is out of range. This means the specified default-label is actually ignored by the `case' insn proper. `IMPLICIT_FIX_EXPR' An alias for a tree code that should be used by default for conversion of floating point values to fixed point. Normally, `FIX_ROUND_EXPR' is used. `FIXUNS_TRUNC_LIKE_FIX_TRUNC' Define this macro if the same instructions that convert a floating point number to a signed fixed point number also convert validly to an unsigned one. `EASY_DIV_EXPR' An alias for a tree code that is the easiest kind of division to compile code for in the general case. It may be `TRUNC_DIV_EXPR', `FLOOR_DIV_EXPR', `CEIL_DIV_EXPR' or `ROUND_DIV_EXPR'. These four division operators differ in how they round the result to an integer. `EASY_DIV_EXPR' is used when it is permissible to use any of those kinds of division and the choice should be made on the basis of efficiency. `DEFAULT_SIGNED_CHAR' An expression whose value is 1 or 0, according to whether the type `char' should be signed or unsigned by default. The user can always override this default with the options `-fsigned-char' and `-funsigned-char'. `SCCS_DIRECTIVE' Define this if the preprocessor should ignore `#sccs' directives and print no error message. `HAVE_VPRINTF' Define this if the library function `vprintf' is available on your system. `MOVE_MAX' The maximum number of bytes that a single instruction can move quickly from memory to memory. `INT_TYPE_SIZE' A C expression for the size in bits of the type `int' on the target machine. If you don't define this, the default is one word. `SHORT_TYPE_SIZE' A C expression for the size in bits of the type `short' on the target machine. If you don't define this, the default is half a word. (If this would be less than one storage unit, it is rounded up to one unit.) `LONG_TYPE_SIZE' A C expression for the size in bits of the type `long' on the target machine. If you don't define this, the default is one word. `LONG_LONG_TYPE_SIZE' A C expression for the size in bits of the type `long long' on the target machine. If you don't define this, the default is two words. `CHAR_TYPE_SIZE' A C expression for the size in bits of the type `char' on the target machine. If you don't define this, the default is one quarter of a word. (If this would be less than one storage unit, it is rounded up to one unit.) `FLOAT_TYPE_SIZE' A C expression for the size in bits of the type `float' on the target machine. If you don't define this, the default is one word. `DOUBLE_TYPE_SIZE' A C expression for the size in bits of the type `double' on the target machine. If you don't define this, the default is two words. `LONG_DOUBLE_TYPE_SIZE' A C expression for the size in bits of the type `long double' on the target machine. If you don't define this, the default is two words. `SLOW_BYTE_ACCESS' Define this macro as a C expression which is nonzero if accessing less than a word of memory (i.e. a `char' or a `short') is slow (requires more than one instruction). `SLOW_ZERO_EXTEND' Define this macro if zero-extension (of a `char' or `short' to an `int') can be done faster if the destination is a register that is known to be zero. If you define this macro, you must have instruction patterns that recognize RTL structures like this: (set (strict-low-part (subreg:QI (reg:SI ...) 0)) ...) and likewise for `HImode'. `SHIFT_COUNT_TRUNCATED' Define this macro if shift instructions ignore all but the lowest few bits of the shift count. It implies that a sign-extend or zero-extend instruction for the shift count can be omitted. `TRULY_NOOP_TRUNCATION (OUTPREC, INPREC)' A C expression which is nonzero if on this machine it is safe to "convert" an integer of INPREC bits to one of OUTPREC bits (where OUTPREC is smaller than INPREC) by merely operating on it as if it had only OUTPREC bits. On many machines, this expression can be 1. `NO_FUNCTION_CSE' Define this macro if it is as good or better to call a constant function address than to call an address kept in a register. `PROMOTE_PROTOTYPES' Define this macro if an argument declared as `char' or `short' in a prototype should actually be passed as an `int'. In addition to avoiding errors in certain cases of mismatch, it also makes for better code on certain machines. `STORE_FLAG_VALUE' A C expression for the value stored by a store-flag instruction (`sCOND') when the condition is true. This is usually 1 or -1; it is required to be an odd number or a negative number. Do not define `STORE_FLAG_VALUE' if the machine has no store-flag instructions. `Pmode' An alias for the machine mode for pointers. Normally the definition can be #define Pmode SImode `FUNCTION_MODE' An alias for the machine mode used for memory references to functions being called, in `call' RTL expressions. On most machines this should be `QImode'. `INSN_MACHINE_INFO' This macro should expand into a C structure type to use for the machine-dependent info field specified with the optional last argument in `define_insn' and `define_peephole' patterns. For example, it might expand into `struct machine_info'; then it would be up to you to define this structure in the `tm.h' file. You do not need to define this macro if you do not write the optional last argument in any of the patterns in the machine description. `DEFAULT_MACHINE_INFO' This macro should expand into a C initializer to use to initialize the machine-dependent info for one insn pattern. It is used for patterns that do not specify the machine-dependent info. If you do not define this macro, zero is used. `CONST_COSTS (X, CODE)' A part of a C `switch' statement that describes the relative costs of constant RTL expressions. It must contain `case' labels for expression codes `const_int', `const', `symbol_ref', `label_ref' and `const_double'. Each case must ultimately reach a `return' statement to return the relative cost of the use of that kind of constant value in an expression. The cost may depend on the precise value of the constant, which is available for examination in X. CODE is the expression code--redundant, since it can be obtained with `GET_CODE (X)'. `DOLLARS_IN_IDENTIFIERS' Define this to be nonzero if the character `$' should be allowed by default in identifier names. File: gcc.info, Node: Assembler Format, Prev: Misc, Up: Machine Macros Output of Assembler Code ======================== `ASM_SPEC' A C string constant that tells the GNU CC driver program options to pass to the assembler. It can also specify how to translate options you give to GNU CC into options for GNU CC to pass to the assembler. See the file `tm-sun3.h' for an example of this. Do not define this macro if it does not need to do anything. `LINK_SPEC' A C string constant that tells the GNU CC driver program options to pass to the linker. It can also specify how to translate options you give to GNU CC into options for GNU CC to pass to the linker. Do not define this macro if it does not need to do anything. `LIB_SPEC' Another C string constant used much like `LINK_SPEC'. The difference between the two is that `LIBS_SPEC' is used at the end of the command given to the linker. If this macro is not defined, a default is provided that loads the standard C library from the usual place. See `gcc.c'. `LIBG_SPEC' Another C string constant used much like `LINK_SPEC'. This controls whether to link `libg.a' when debugging. Some systems expect this; others do not have any `libg.a'. If this macro is not defined, a default is provided that loads the `libg.a' provided `-g' is specified. See `gcc.c'. `STARTFILE_SPEC' Another C string constant used much like `LINK_SPEC'. The difference between the two is that `STARTFILE_SPEC' is used at the very beginning of the command given to the linker. If this macro is not defined, a default is provided that loads the standard C startup file from the usual place. See `gcc.c'. `STANDARD_EXEC_PREFIX' Define this macro as a C string constant if you wish to override the standard choice of `/usr/local/lib/gcc-' as the default prefix to try when searching for the executable files of the compiler. The prefix specified by the `-B' option, if any, is tried before the default prefix. After the default prefix, if the executable is not found that way, `/usr/lib/gcc-' is tried next; then the directories in your search path for shell commands are searched. `STANDARD_STARTFILE_PREFIX' Define this macro as a C string constant if you wish to override the standard choice of `/usr/local/lib/' as the default prefix to try when searching for startup files such as `crt0.o'. In this search, all the prefixes tried for executable files are tried first. Then comes the default startfile prefix specified by this macro, followed by the prefixes `/lib/' and `/usr/lib/' as last resorts. `ASM_FILE_START (STREAM)' A C expression which outputs to the stdio stream STREAM some appropriate text to go at the start of an assembler file. Normally this macro is defined to output a line containing `#NO_APP', which is a comment that has no effect on most assemblers but tells the GNU assembler that it can save time by not checking for certain assembler constructs. On systems that use SDB, it is necessary to output certain commands; see `tm-attasm.h'. `ASM_FILE_END (STREAM)' A C expression which outputs to the stdio stream STREAM some appropriate text to go at the end of an assembler file. If this macro is not defined, the default is to output nothing special at the end of the file. Most systems don't require any definition. On systems that use SDB, it is necessary to output certain commands; see `tm-attasm.h'. `ASM_IDENTIFY_GCC (FILE)' A C statement to output assembler commands which will identify the object file as having been compiled with GNU CC (or another GNU compiler). If you don't define this macro, the string `gcc_compiled.:' is output. This string is calculated to define a symbol which, on BSD systems, will never be defined for any other reason. GDB checks for the presence of this symbol when reading the symbol table of an executable. On non-BSD systems, you must arrange communication with GDB in some other fashion. If GDB is not used on your system, you can define this macro with an empty body. `ASM_APP_ON' A C string constant for text to be output before each `asm' statement or group of consecutive ones. Normally this is `"#APP"', which is a comment that has no effect on most assemblers but tells the GNU assembler that it must check the lines that follow for all valid assembler constructs. `ASM_APP_OFF' A C string constant for text to be output after each `asm' statement or group of consecutive ones. Normally this is `"#NO_APP"', which tells the GNU assembler to resume making the time-saving assumptions that are valid for ordinary compiler output. `TEXT_SECTION_ASM_OP' A C string constant for the assembler operation that should precede instructions and read-only data. Normally `".text"' is right. `DATA_SECTION_ASM_OP' A C string constant for the assembler operation to identify the following data as writable initialized data. Normally `".data"' is right. `EXTRA_SECTIONS' A list of names for sections other than the standard two, which are `in_text' and `in_data'. You need not define this macro on a system with no other sections (that GCC needs to use). `EXTRA_SECTION_FUNCTIONS' One or more functions to be defined in `varasm.c'. These functions should do jobs analogous to those of `text_section' and `data_section', for your additional sections. Do not define this macro if you do not define `EXTRA_SECTIONS'. `SELECT_SECTION (EXP)' A C statement or statements to switch to the appropriate section for output of EXP. You can assume that EXP is either a `VAR_DECL' node or a constant of some sort. Select the section by calling `text_section' or one of the alternatives for other sections. Do not define this macro if you use only the standard two sections and put all read-only variables and constants in the text section. `SELECT_RTX_SECTION (MODE, RTX)' A C statement or statements to switch to the appropriate section for output of RTX in mode MODE. You can assume that RTX is some kind of constant in RTL. The argument MODE is redundant except in the case of a `const_int' rtx. Select the section by calling `text_section' or one of the alternatives for other sections. Do not define this macro if you use only the standard two sections and put all constants in the text section. `REGISTER_NAMES' A C initializer containing the assembler's names for the machine registers, each one as a C string constant. This is what translates register numbers in the compiler into assembler language. `DBX_REGISTER_NUMBER (REGNO)' A C expression that returns the DBX register number for the compiler register number REGNO. In simple cases, the value of this expression may be REGNO itself. But sometimes there are some registers that the compiler knows about and DBX does not, or vice versa. In such cases, some register may need to have one number in the compiler and another for DBX. `DBX_DEBUGGING_INFO' Define this macro if GNU CC should produce debugging output for DBX in response to the `-g' option. `SDB_DEBUGGING_INFO' Define this macro if GNU CC should produce debugging output for SDB in response to the `-g' option. `PUT_SDB_OP' Define these macros to override the assembler syntax for the special SDB assembler directives. See `sdbout.c' for a list of these macros and their arguments. If the standard syntax is used, you need not define them yourself. `SDB_GENERATE_FAKE' Define this macro to override the usual method of constructing a dummy name for anonymous structure and union types. See `sdbout.c' for more information. `DBX_NO_XREFS' Define this macro if DBX on your system does not support the construct `xsTAGNAME'. On some systems, this construct is used to describe a forward reference to a structure named TAGNAME. On other systems, this construct is not supported at all. `DBX_CONTIN_LENGTH' A symbol name in DBX-format debugging information is normally continued (split into two separate `.stabs' directives) when it exceeds a certain length (by default, 80 characters). On some operating systems, DBX requires this splitting; on others, splitting must not be done. You can inhibit splitting by defining this macro with the value zero. You can override the default splitting-length by defining this macro as an expression for the length you desire. `DBX_CONTIN_CHAR' Normally continuation is indicated by adding a `\' character to the end of a `.stabs' string when a continuation follows. To use a different character instead, define this macro as a character constant for the character you want to use. Do not define this macro if backslash is correct for your system. `DBX_STATIC_STAB_DATA_SECTION' Define this macro if it is necessary to go to the data section before outputting the `.stabs' pseudo-op for a non-global static variable. `ASM_OUTPUT_LABEL (STREAM, NAME)' A C statement (sans semicolon) to output to the stdio stream STREAM the assembler definition of a label named NAME. Use the expression `assemble_name (STREAM, NAME)' to output the name itself; before and after that, output the additional assembler syntax for defining the name, and a newline. `ASM_DECLARE_FUNCTION_NAME (STREAM, NAME, DECL)' A C statement (sans semicolon) to output to the stdio stream STREAM any text necessary for declaring the name NAME of a function which is being defined. This macro is responsible for outputting the label definition (perhaps using `ASM_OUTPUT_LABEL'). The argument DECL is the `FUNCTION_DECL' tree node representing the function. If this macro is not defined, then the function name is defined in the usual manner as a label (by means of `ASM_OUTPUT_LABEL'). `ASM_GLOBALIZE_LABEL (STREAM, NAME)' A C statement (sans semicolon) to output to the stdio stream STREAM some commands that will make the label NAME global; that is, available for reference from other files. Use the expression `assemble_name (STREAM, NAME)' to output the name itself; before and after that, output the additional assembler syntax for making that name global, and a newline. `ASM_OUTPUT_EXTERNAL (STREAM, DECL, NAME)' A C statement (sans semicolon) to output to the stdio stream STREAM any text necessary for declaring the name of an external symbol named NAME which is referenced in this compilation but not defined. The value of DECL is the tree node for the declaration. This macro need not be defined if it does not need to output anything. The GNU assembler and most Unix assemblers don't require anything. `ASM_OUTPUT_LABELREF (STREAM, NAME)' A C statement to output to the stdio stream STREAM a reference in assembler syntax to a label named NAME. The character `_' should be added to the front of the name, if that is customary on your operating system, as it is in most Berkeley Unix systems. This macro is used in `assemble_name'. `ASM_GENERATE_INTERNAL_LABEL (STRING, PREFIX, NUM)' A C statement to store into the string STRING a label whose name is made from the string PREFIX and the number NUM. This string, when output subsequently by `ASM_OUTPUT_LABELREF', should produce the same output that `ASM_OUTPUT_INTERNAL_LABEL' would produce with the same PREFIX and NUM. `ASM_OUTPUT_INTERNAL_LABEL (STREAM, PREFIX, NUM)' A C statement to output to the stdio stream STREAM a label whose name is made from the string PREFIX and the number NUM. These labels are used for internal purposes, and there is no reason for them to appear in the symbol table of the object file. On many systems, the letter `L' at the beginning of a label has this effect. The usual definition of this macro is as follows: fprintf (STREAM, "L%s%d:\n", PREFIX, NUM) `ASM_OUTPUT_CASE_LABEL (STREAM, PREFIX, NUM, TABLE)' Define this if the label before a jump-table needs to be output specially. The first three arguments are the same as for `ASM_OUTPUT_INTERNAL_LABEL'; the fourth argument is the jump-table which follows (a `jump_insn' containing an `addr_vec' or `addr_diff_vec'). This feature is used on system V to output a `swbeg' statement for the table. If this macro is not defined, these labels are output with `ASM_OUTPUT_INTERNAL_LABEL'. `ASM_OUTPUT_CASE_END (STREAM, NUM, TABLE)' Define this if something special must be output at the end of a jump-table. The definition should be a C statement to be executed after the assembler code for the table is written. It should write the appropriate code to stdio stream STREAM. The argument TABLE is the jump-table insn, and NUM is the label-number of the preceding label. If this macro is not defined, nothing special is output at the end of the jump-table. `ASM_OUTPUT_ALIGN_CODE (FILE)' A C expression to output text to align the location counter in the way that is desirable at a point in the code that is reached only by jumping. This macro need not be defined if you don't want any special alignment to be done at such a time. Most machine descriptions do not currently define the macro. `ASM_FORMAT_PRIVATE_NAME (OUTVAR, NAME, NUMBER)' A C expression to assign to OUTVAR (which is a variable of type `char *') a newly allocated string made from the string NAME and the number NUMBER, with some suitable punctuation added. Use `alloca' to get space for the string. This string will be used as the argument to `ASM_OUTPUT_LABELREF' to produce an assembler label for an internal static variable whose name is NAME. Therefore, the string must be such as to result in valid assembler code. The argument NUMBER is different each time this macro is executed; it prevents conflicts between similarly-named internal static variables in different scopes. Ideally this string should not be a valid C identifier, to prevent any conflict with the user's own symbols. Most assemblers allow periods or percent signs in assembler symbols; putting at least one of these between the name and the number will suffice. `ASM_OUTPUT_REG_PUSH (STREAM, REGNO)' A C expression to output to STREAM some assembler code which will push hard register number REGNO onto the stack. The code need not be optimal, since this macro is used only when profiling. `ASM_OUTPUT_REG_POP (STREAM, REGNO)' A C expression to output to STREAM some assembler code which will pop hard register number REGNO off of the stack. The code need not be optimal, since this macro is used only when profiling. `ASM_OUTPUT_ADDR_DIFF_ELT (STREAM, VALUE, REL)' This macro should be provided on machines where the addresses in a dispatch table are relative to the table's own address. The definition should be a C statement to output to the stdio stream STREAM an assembler pseudo-instruction to generate a difference between two labels. VALUE and REL are the numbers of two internal labels. The definitions of these labels are output using `ASM_OUTPUT_INTERNAL_LABEL', and they must be printed in the same way here. For example, fprintf (STREAM, "\t.word L%d-L%d\n", VALUE, REL) `ASM_OUTPUT_ADDR_VEC_ELT (STREAM, VALUE)' This macro should be provided on machines where the addresses in a dispatch table are absolute. The definition should be a C statement to output to the stdio stream STREAM an assembler pseudo-instruction to generate a reference to a label. VALUE is the number of an internal label whose definition is output using `ASM_OUTPUT_INTERNAL_LABEL'. For example, fprintf (STREAM, "\t.word L%d\n", VALUE) `ASM_OUTPUT_DOUBLE (STREAM, VALUE)' A C statement to output to the stdio stream STREAM an assembler instruction to assemble a `double' constant whose value is VALUE. VALUE will be a C expression of type `double'. `ASM_OUTPUT_FLOAT (STREAM, VALUE)' A C statement to output to the stdio stream STREAM an assembler instruction to assemble a `float' constant whose value is VALUE. VALUE will be a C expression of type `float'. `ASM_OUTPUT_INT (STREAM, EXP)' `ASM_OUTPUT_SHORT (STREAM, EXP)' `ASM_OUTPUT_CHAR (STREAM, EXP)' A C statement to output to the stdio stream STREAM an assembler instruction to assemble a `int', `short' or `char' constant whose value is VALUE. The argument EXP will be an RTL expression which represents a constant value. Use `output_addr_const (STREAM, EXP)' to output this value as an assembler expression. `ASM_OUTPUT_DOUBLE_INT (STREAM, EXP)' A C statement to output to the stdio stream STREAM an assembler instruction to assemble a `long long' constant whose value is EXP. The argument EXP will be an RTL expression which represents a constant value. It may be a `const_double' RTX, or it may be an ordinary single-precision constant. In the latter case, you should zero-extend it. `ASM_OUTPUT_BYTE (STREAM, VALUE)' A C statement to output to the stdio stream STREAM an assembler instruction to assemble a single byte containing the number VALUE. `ASM_OUTPUT_ASCII (STREAM, PTR, LEN)' A C statement to output to the stdio stream STREAM an assembler instruction to assemble a string constant containing the LEN bytes at PTR. PTR will be a C expression of type `char *' and LEN a C expression of type `int'. If the assembler has a `.ascii' pseudo-op as found in the Berkeley Unix assembler, do not define the macro `ASM_OUTPUT_ASCII'. `ASM_OUTPUT_SKIP (STREAM, NBYTES)' A C statement to output to the stdio stream STREAM an assembler instruction to advance the location counter by NBYTES bytes. NBYTES will be a C expression of type `int'. `ASM_OUTPUT_ALIGN (STREAM, POWER)' A C statement to output to the stdio stream STREAM an assembler instruction to advance the location counter to a multiple of 2 to the POWER bytes. POWER will be a C expression of type `int'. `ASM_OUTPUT_COMMON (STREAM, NAME, SIZE, ROUNDED)' A C statement (sans semicolon) to output to the stdio stream STREAM the assembler definition of a common-label named NAME whose size is SIZE bytes. The variable ROUNDED is the size rounded up to whatever alignment the caller wants. Use the expression `assemble_name (STREAM, NAME)' to output the name itself; before and after that, output the additional assembler syntax for defining the name, and a newline. This macro controls how the assembler definitions of uninitialized global variables are output. `ASM_OUTPUT_LOCAL (STREAM, NAME, SIZE, ROUNDED)' A C statement (sans semicolon) to output to the stdio stream STREAM the assembler definition of a local-common-label named NAME whose size is SIZE bytes. The variable ROUNDED is the size rounded up to whatever alignment the caller wants. Use the expression `assemble_name (STREAM, NAME)' to output the name itself; before and after that, output the additional assembler syntax for defining the name, and a newline. This macro controls how the assembler definitions of uninitialized static variables are output. `ASM_OUTPUT_SOURCE_FILENAME (STREAM, NAME)' A C statment to output DBX or SDB debugging information which indicates that filename NAME is the current source file to the stdio stream STREAM. This macro need not be defined if the standard form of debugging information for the debugger in use is appropriate. `ASM_OUTPUT_SOURCE_LINE (STREAM, LINE)' A C statment to output DBX or SDB debugging information before code for line number LINE of the current source file to the stdio stream STREAM. This macro need not be defined if the standard form of debugging information for the debugger in use is appropriate. `ASM_OUTPUT_IDENT (STREAM, STRING)' A C statement to output something to the assembler file to handle a `#ident' directive containing the text STRING. If this macro is not defined, nothing is output for a `#ident' directive. `TARGET_BELL' A C constant expression for the integer value for escape sequence `\a'. `TARGET_BS' `TARGET_TAB' `TARGET_NEWLINE' C constant expressions for the integer values for escape sequences `\b', `\t' and `\n'. `TARGET_VT' `TARGET_FF' `TARGET_CR' C constant expressions for the integer values for escape sequences `\v', `\f' and `\r'. `ASM_OUTPUT_OPCODE (STREAM, PTR)' Define this macro if you are using an unusual assembler that requires different names for the machine instructions. The definition is a C statement or statements which output an assembler instruction opcode to the stdio stream STREAM. The macro-operand PTR is a variable of type `char *' which points to the opcode name in its "internal" form--the form that is written in the machine description. The definition should output the opcode name to STREAM, performing any translation you desire, and increment the variable PTR to point at the end of the opcode so that it will not be output twice. In fact, your macro definition may process less than the entire opcode name, or more than the opcode name; but if you want to process text that includes `%'-sequences to substitute operands, you must take care of the substitution yourself. Just be sure to increment PTR over whatever text should not be output normally. If you need to look at the operand values, they can be found as the elements of `recog_operand'. If the macro definition does nothing, the instruction is output in the usual way. `FINAL_PRESCAN_INSN (INSN, OPVEC, NOPERANDS)' If defined, a C statement to be executed just prior to the output of assembler code for INSN, to modify the extracted operands so they will be output differently. Here the argument OPVEC is the vector containing the operands extracted from INSN, and NOPERANDS is the number of elements of the vector which contain meaningful data for this insn. The contents of this vector are what will be used to convert the insn template into assembler code, so you can change the assembler output by changing the contents of the vector. This macro is useful when various assembler syntaxes share a single file of instruction patterns; by defining this macro differently, you can cause a large class of instructions to be output differently (such as with rearranged operands). Naturally, variations in assembler syntax affecting individual insn patterns ought to be handled by writing conditional output routines in those patterns. If this macro is not defined, it is equivalent to a null statement. `PRINT_OPERAND (STREAM, X, CODE)' A C compound statement to output to stdio stream STREAM the assembler syntax for an instruction operand X. X is an RTL expression. CODE is a value that can be used to specify one of several ways of printing the operand. It is used when identical operands must be printed differently depending on the context. CODE comes from the `%' specification that was used to request printing of the operand. If the specification was just `%DIGIT' then CODE is 0; if the specification was `%LTR DIGIT' then CODE is the ASCII code for LTR. If X is a register, this macro should print the register's name. The names can be found in an array `reg_names' whose type is `char *[]'. `reg_names' is initialized from `REGISTER_NAMES'. When the machine description has a specification `%PUNCT' (a `%' followed by a punctuation character), this macro is called with a null pointer for X and the punctuation character for CODE. `PRINT_OPERAND_PUNCT_VALID_P (CODE)' A C expression which evaluates to true if CODE is a valid punctuation character for use in the `PRINT_OPERAND' macro. If `PRINT_OPERAND_PUNCT_VALID_P' is not defined, it means that no punctuation characters (except for the standard one, `%') are used in this way. `PRINT_OPERAND_ADDRESS (STREAM, X)' A C compound statement to output to stdio stream STREAM the assembler syntax for an instruction operand that is a memory reference whose address is X. X is an RTL expression. `ASM_OPEN_PAREN' `ASM_CLOSE_PAREN' These macros are defined as C string constant, describing the syntax in the assembler for grouping arithmetic expressions. The following definitions are correct for most assemblers: #define ASM_OPEN_PAREN "(" #define ASM_CLOSE_PAREN ")"