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tcode.c
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C/C++ Source or Header
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2002-03-27
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25KB
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1,115 lines
/*
* tcode.c -- translator functions for traversing parse trees and generating
* code.
*/
#include "../h/gsupport.h"
#include "tproto.h"
#include "tglobals.h"
#include "tree.h"
#include "ttoken.h"
#include "tsym.h"
/*
* Prototypes.
*/
static int alclab (int n);
static void binop (int op);
static void emit (char *s);
static void emitl (char *s,int a);
static void emitlab (int l);
static void emitn (char *s,int a);
static void emits (char *s,char *a);
static void emitfile (nodeptr n);
static void emitline (nodeptr n);
static void setloc (nodeptr n);
static int traverse (nodeptr t);
static void unopa (int op, nodeptr t);
static void unopb (int op);
extern int tfatals;
extern int nocode;
/*
* Code generator parameters.
*/
#define LoopDepth 20 /* max. depth of nested loops */
#define CaseDepth 10 /* max. depth of nested case statements */
#define CreatDepth 10 /* max. depth of nested create statements */
/*
* loopstk structures hold information about nested loops.
*/
struct loopstk {
int nextlab; /* label for next exit */
int breaklab; /* label for break exit */
int markcount; /* number of marks */
int ltype; /* loop type */
};
/*
* casestk structure hold information about case statements.
*/
struct casestk {
int endlab; /* label for exit from case statement */
nodeptr deftree; /* pointer to tree for default clause */
};
/*
* creatstk structures hold information about create statements.
*/
struct creatstk {
int nextlab; /* previous value of nextlab */
int breaklab; /* previous value of breaklab */
};
static int nextlab; /* next label allocated by alclab() */
/*
* codegen - traverse tree t, generating code.
*/
void codegen(t)
nodeptr t;
{
nextlab = 1;
traverse(t);
}
/*
* traverse - traverse tree rooted at t and generate code. This is just
* plug and chug code for each of the node types.
*/
static int traverse(t)
register nodeptr t;
{
register int lab, n, i;
struct loopstk loopsave;
static struct loopstk loopstk[LoopDepth]; /* loop stack */
static struct loopstk *loopsp;
static struct casestk casestk[CaseDepth]; /* case stack */
static struct casestk *casesp;
static struct creatstk creatstk[CreatDepth]; /* create stack */
static struct creatstk *creatsp;
n = 1;
switch (TType(t)) {
case N_Activat: /* co-expression activation */
if (Val0(Tree0(t)) == AUGAT) {
emit("pnull");
}
traverse(Tree2(t)); /* evaluate result expression */
if (Val0(Tree0(t)) == AUGAT)
emit("sdup");
traverse(Tree1(t)); /* evaluate activate expression */
setloc(t);
emit("coact");
if (Val0(Tree0(t)) == AUGAT)
emit("asgn");
free(Tree0(t));
break;
case N_Alt: /* alternation */
lab = alclab(2);
emitl("mark", lab);
loopsp->markcount++;
traverse(Tree0(t)); /* evaluate first alternative */
loopsp->markcount--;
#ifdef EventMon
setloc(t);
#endif /* EventMon */
emit("esusp"); /* and suspend with its result */
emitl("goto", lab+1);
emitlab(lab);
traverse(Tree1(t)); /* evaluate second alternative */
emitlab(lab+1);
break;
case N_Augop: /* augmented assignment */
case N_Binop: /* or a binary operator */
emit("pnull");
traverse(Tree1(t));
if (TType(t) == N_Augop)
emit("dup");
traverse(Tree2(t));
setloc(t);
binop((int)Val0(Tree0(t)));
free(Tree0(t));
break;
case N_Bar: /* repeated alternation */
lab = alclab(1);
emitlab(lab);
emit("mark0"); /* fail if expr fails first time */
loopsp->markcount++;
traverse(Tree0(t)); /* evaluate first alternative */
loopsp->markcount--;
emitl("chfail", lab); /* change to loop on failure */
emit("esusp"); /* suspend result */
break;
case N_Break: /* break expression */
if (loopsp->breaklab <= 0)
nfatal(t, "invalid context for break", NULL);
else {
for (i = 0; i < loopsp->markcount; i++)
emit("unmark");
loopsave = *loopsp--;
traverse(Tree0(t));
*++loopsp = loopsave;
emitl("goto", loopsp->breaklab);
}
break;
case N_Case: /* case expression */
lab = alclab(1);
casesp++;
casesp->endlab = lab;
casesp->deftree = NULL;
emit("mark0");
loopsp->markcount++;
traverse(Tree0(t)); /* evaluate control expression */
loopsp->markcount--;
emit("eret");
traverse(Tree1(t)); /* do rest of case (CLIST) */
if (casesp->deftree != NULL) { /* evaluate default clause */
emit("pop");
traverse(casesp->deftree);
}
else
emit("efail");
emitlab(lab); /* end label */
casesp--;
break;
case N_Ccls: /* case expression clause */
if (TType(Tree0(t)) == N_Res && /* default clause */
Val0(Tree0(t)) == DEFAULT) {
if (casesp->deftree != NULL)
nfatal(t, "more than one default clause", NULL);
else
casesp->deftree = Tree1(t);
free(Tree0(t));
}
else { /* case clause */
lab = alclab(1);
emitl("mark", lab);
loopsp->markcount++;
emit("ccase");
traverse(Tree0(t)); /* evaluate selector */
setloc(t);
emit("eqv");
loopsp->markcount--;
emit("unmark");
emit("pop");
traverse(Tree1(t)); /* evaluate expression */
emitl("goto", casesp->endlab); /* goto end label */
emitlab(lab); /* label for next clause */
}
break;
case N_Clist: /* list of case clauses */
traverse(Tree0(t));
traverse(Tree1(t));
break;
case N_Conj: /* conjunction */
if (Val0(Tree0(t)) == AUGAND) {
emit("pnull");
}
traverse(Tree1(t));
if (Val0(Tree0(t)) != AUGAND)
emit("pop");
traverse(Tree2(t));
if (Val0(Tree0(t)) == AUGAND) {
setloc(t);
emit("asgn");
}
free(Tree0(t));
break;
case N_Create: /* create expression */
creatsp++;
creatsp->nextlab = loopsp->nextlab;
creatsp->breaklab = loopsp->breaklab;
loopsp->nextlab = 0; /* make break and next illegal */
loopsp->breaklab = 0;
lab = alclab(3);
emitl("goto", lab+2); /* skip over code for co-expression */
emitlab(lab); /* entry point */
emit("pop"); /* pop the result from activation */
emitl("mark", lab+1);
loopsp->markcount++;
traverse(Tree0(t)); /* traverse code for co-expression */
loopsp->markcount--;
setloc(t);
emit("coret"); /* return to activator */
emit("efail"); /* drive co-expression */
emitlab(lab+1); /* loop on exhaustion */
emit("cofail"); /* and fail each time */
emitl("goto", lab+1);
emitlab(lab+2);
emitl("create", lab); /* create entry block */
loopsp->nextlab = creatsp->nextlab; /* legalize break and next */
loopsp->breaklab = creatsp->breaklab;
creatsp--;
break;
case N_Cset: /* cset literal */
emitn("cset", (int)Val0(t));
break;
case N_Elist: /* expression list */
n = traverse(Tree0(t));
n += traverse(Tree1(t));
break;
case N_Empty: /* a missing expression */
emit("pnull");
break;
case N_Field: /* field reference */
emit("pnull");
traverse(Tree0(t));
setloc(t);
emits("field", Str0(Tree1(t)));
free(Tree1(t));
break;
case N_Id: /* identifier */
emitn("var", (int)Val0(t));
break;
case N_If: /* if expression */
if (TType(Tree2(t)) == N_Empty) {
lab = 0;
emit("mark0");
}
else {
lab = alclab(2);
emitl("mark", lab);
}
loopsp->markcount++;
traverse(Tree0(t));
loopsp->markcount--;
emit("unmark");
traverse(Tree1(t));
if (lab > 0) {
emitl("goto", lab+1);
emitlab(lab);
traverse(Tree2(t));
emitlab(lab+1);
}
else
free(Tree2(t));
break;
case N_Int: /* integer literal */
emitn("int", (int)Val0(t));
break;
case N_Apply: /* application */
traverse(Tree0(t));
traverse(Tree1(t));
emitn("invoke", -1);
break;
case N_Invok: /* invocation */
if (TType(Tree0(t)) != N_Empty) {
traverse(Tree0(t));
}
else {
emit("pushn1"); /* default to -1(e1,...,en) */
free(Tree0(t));
}
if (TType(Tree1(t)) == N_Empty) {
n = 0;
free(Tree1(t));
}
else
n = traverse(Tree1(t));
setloc(t);
emitn("invoke", n);
n = 1;
break;
case N_Key: /* keyword reference */
setloc(t);
emits("keywd", Str0(t));
break;
case N_Limit: /* limitation */
traverse(Tree1(t));
setloc(t);
emit("limit");
loopsp->markcount++;
traverse(Tree0(t));
loopsp->markcount--;
emit("lsusp");
break;
case N_List: /* list construction */
emit("pnull");
if (TType(Tree0(t)) == N_Empty) {
n = 0;
free(Tree0(t));
}
else
n = traverse(Tree0(t));
setloc(t);
emitn("llist", n);
n = 1;
break;
case N_Loop: /* loop */
switch ((int)Val0(Tree0(t))) {
case EVERY:
lab = alclab(2);
loopsp++;
loopsp->ltype = EVERY;
loopsp->nextlab = lab;
loopsp->breaklab = lab + 1;
loopsp->markcount = 1;
emit("mark0");
traverse(Tree1(t));
emit("pop");
if (TType(Tree2(t)) != N_Empty) { /* every e1 do e2 */
emit("mark0");
loopsp->ltype = N_Loop;
loopsp->markcount++;
traverse(Tree2(t));
loopsp->markcount--;
emit("unmark");
}
else
free(Tree2(t));
emitlab(loopsp->nextlab);
emit("efail");
emitlab(loopsp->breaklab);
loopsp--;
break;
case REPEAT:
lab = alclab(3);
loopsp++;
loopsp->ltype = N_Loop;
loopsp->nextlab = lab + 1;
loopsp->breaklab = lab + 2;
loopsp->markcount = 1;
emitlab(lab);
emitl("mark", lab);
traverse(Tree1(t));
emitlab(loopsp->nextlab);
emit("unmark");
emitl("goto", lab);
emitlab(loopsp->breaklab);
loopsp--;
free(Tree2(t));
break;
case SUSPEND: /* suspension expression */
if (creatsp > creatstk)
nfatal(t, "invalid context for suspend", NULL);
lab = alclab(2);
loopsp++;
loopsp->ltype = EVERY; /* like every ... do for next */
loopsp->nextlab = lab;
loopsp->breaklab = lab + 1;
loopsp->markcount = 1;
emit("mark0");
traverse(Tree1(t));
setloc(t);
emit("psusp");
emit("pop");
if (TType(Tree2(t)) != N_Empty) { /* suspend e1 do e2 */
emit("mark0");
loopsp->ltype = N_Loop;
loopsp->markcount++;
traverse(Tree2(t));
loopsp->markcount--;
emit("unmark");
}
else
free(Tree2(t));
emitlab(loopsp->nextlab);
emit("efail");
emitlab(loopsp->breaklab);
loopsp--;
break;
case WHILE:
lab = alclab(3);
loopsp++;
loopsp->ltype = N_Loop;
loopsp->nextlab = lab + 1;
loopsp->breaklab = lab + 2;
loopsp->markcount = 1;
emitlab(lab);
emit("mark0");
traverse(Tree1(t));
if (TType(Tree2(t)) != N_Empty) {
emit("unmark");
emitl("mark", lab);
traverse(Tree2(t));
}
else
free(Tree2(t));
emitlab(loopsp->nextlab);
emit("unmark");
emitl("goto", lab);
emitlab(loopsp->breaklab);
loopsp--;
break;
case UNTIL:
lab = alclab(4);
loopsp++;
loopsp->ltype = N_Loop;
loopsp->nextlab = lab + 2;
loopsp->breaklab = lab + 3;
loopsp->markcount = 1;
emitlab(lab);
emitl("mark", lab+1);
traverse(Tree1(t));
emit("unmark");
emit("efail");
emitlab(lab+1);
emitl("mark", lab);
traverse(Tree2(t));
emitlab(loopsp->nextlab);
emit("unmark");
emitl("goto", lab);
emitlab(loopsp->breaklab);
loopsp--;
break;
}
free(Tree0(t));
break;
case N_Next: /* next expression */
if (loopsp < loopstk || loopsp->nextlab <= 0)
nfatal(t, "invalid context for next", NULL);
else {
if (loopsp->ltype != EVERY && loopsp->markcount > 1)
for (i = 0; i < loopsp->markcount - 1; i++)
emit("unmark");
emitl("goto", loopsp->nextlab);
}
break;
case N_Not: /* not expression */
lab = alclab(1);
emitl("mark", lab);
loopsp->markcount++;
traverse(Tree0(t));
loopsp->markcount--;
emit("unmark");
emit("efail");
emitlab(lab);
emit("pnull");
break;
case N_Proc: /* procedure */
loopsp = loopstk;
loopsp->nextlab = 0;
loopsp->breaklab = 0;
loopsp->markcount = 0;
casesp = casestk;
creatsp = creatstk;
writecheck(fprintf(codefile, "proc %s\n", Str0(Tree0(t))));
emitfile(t);
lout(codefile);
constout(codefile);
emit("declend");
emitline(t);
if (TType(Tree1(t)) != N_Empty) {
lab = alclab(1);
emitl("init", lab);
emitl("mark", lab);
traverse(Tree1(t));
emit("unmark");
emitlab(lab);
}
else
free(Tree1(t));
if (TType(Tree2(t)) != N_Empty)
traverse(Tree2(t));
else
free(Tree2(t));
setloc(Tree3(t));
emit("pfail");
emit("end");
if (!silent)
fprintf(stderr, " %s\n", Str0(Tree0(t)));
free(Tree0(t));
free(Tree3(t));
break;
case N_Real: /* real literal */
emitn("real", (int)Val0(t));
break;
case N_Ret: /* return expression */
if (creatsp > creatstk)
nfatal(t, "invalid context for return or fail", NULL);
if (Val0(Tree0(t)) == FAIL)
free(Tree1(t));
else {
lab = alclab(1);
emitl("mark", lab);
loopsp->markcount++;
traverse(Tree1(t));
loopsp->markcount--;
setloc(t);
emit("pret");
emitlab(lab);
}
setloc(t);
emit("pfail");
free(Tree0(t));
break;
case N_Scan: /* scanning expression */
if (Val0(Tree0(t)) == AUGQMARK)
emit("pnull");
traverse(Tree1(t));
if (Val0(Tree0(t)) == AUGQMARK)
emit("sdup");
setloc(t);
emit("bscan");
traverse(Tree2(t));
setloc(t);
emit("escan");
if (Val0(Tree0(t)) == AUGQMARK)
emit("asgn");
free(Tree0(t));
break;
case N_Sect: /* section operation */
emit("pnull");
traverse(Tree1(t));
traverse(Tree2(t));
if (Val0(Tree0(t)) == PCOLON || Val0(Tree0(t)) == MCOLON)
emit("dup");
traverse(Tree3(t));
setloc(Tree0(t));
if (Val0(Tree0(t)) == PCOLON)
emit("plus");
else if (Val0(Tree0(t)) == MCOLON)
emit("minus");
setloc(t);
emit("sect");
free(Tree0(t));
break;
case N_Slist: /* semicolon-separated expr list */
lab = alclab(1);
emitl("mark", lab);
loopsp->markcount++;
traverse(Tree0(t));
loopsp->markcount--;
emit("unmark");
emitlab(lab);
traverse(Tree1(t));
break;
case N_Str: /* string literal */
emitn("str", (int)Val0(t));
break;
case N_To: /* to expression */
emit("pnull");
traverse(Tree0(t));
traverse(Tree1(t));
emit("push1");
setloc(t);
emit("toby");
break;
case N_ToBy: /* to-by expression */
emit("pnull");
traverse(Tree0(t));
traverse(Tree1(t));
traverse(Tree2(t));
setloc(t);
emit("toby");
break;
case N_Unop: /* unary operator */
unopa((int)Val0(Tree0(t)),t);
traverse(Tree1(t));
setloc(t);
unopb((int)Val0(Tree0(t)));
free(Tree0(t));
break;
default:
emitn("?????", TType(t));
tsyserr("traverse: undefined node type");
}
free(t);
return n;
}
/*
* binop emits code for binary operators. For non-augmented operators,
* the name of operator is emitted. For augmented operators, an "asgn"
* is emitted after the name of the operator.
*/
static void binop(op)
int op;
{
register int asgn;
register char *name;
asgn = 0;
switch (op) {
case ASSIGN:
name = "asgn";
break;
case AUGCARET:
asgn++;
case CARET:
name = "power";
break;
case AUGCONCAT:
asgn++;
case CONCAT:
name = "cat";
break;
case AUGDIFF:
asgn++;
case DIFF:
name = "diff";
break;
case AUGEQUIV:
asgn++;
case EQUIV:
name = "eqv";
break;
case AUGINTER:
asgn++;
case INTER:
name = "inter";
break;
case LBRACK:
name = "subsc";
break;
case AUGLCONCAT:
asgn++;
case LCONCAT:
name = "lconcat";
break;
case AUGSEQ:
asgn++;
case SEQ:
name = "lexeq";
break;
case AUGSGE:
asgn++;
case SGE:
name = "lexge";
break;
case AUGSGT:
asgn++;
case SGT:
name = "lexgt";
break;
case AUGSLE:
asgn++;
case SLE:
name = "lexle";
break;
case AUGSLT:
asgn++;
case SLT:
name = "lexlt";
break;
case AUGSNE:
asgn++;
case SNE:
name = "lexne";
break;
case AUGMINUS:
asgn++;
case MINUS:
name = "minus";
break;
case AUGMOD:
asgn++;
case MOD:
name = "mod";
break;
case AUGNEQUIV:
asgn++;
case NEQUIV:
name = "neqv";
break;
case AUGNMEQ:
asgn++;
case NMEQ:
name = "numeq";
break;
case AUGNMGE:
asgn++;
case NMGE:
name = "numge";
break;
case AUGNMGT:
asgn++;
case NMGT:
name = "numgt";
break;
case AUGNMLE:
asgn++;
case NMLE:
name = "numle";
break;
case AUGNMLT:
asgn++;
case NMLT:
name = "numlt";
break;
case AUGNMNE:
asgn++;
case NMNE:
name = "numne";
break;
case AUGPLUS:
asgn++;
case PLUS:
name = "plus";
break;
case REVASSIGN:
name = "rasgn";
break;
case REVSWAP:
name = "rswap";
break;
case AUGSLASH:
asgn++;
case SLASH:
name = "div";
break;
case AUGSTAR:
asgn++;
case STAR:
name = "mult";
break;
case SWAP:
name = "swap";
break;
case AUGUNION:
asgn++;
case UNION:
name = "unions";
break;
default:
emitn("?binop", op);
tsyserr("binop: undefined binary operator");
}
emit(name);
if (asgn)
emit("asgn");
}
/*
* unopa and unopb handle code emission for unary operators. unary operator
* sequences that are the same as binary operator sequences are recognized
* by the lexical analyzer as binary operators. For example, ~===x means to
* do three tab(match(...)) operations and then a cset complement, but the
* lexical analyzer sees the operator sequence as the "neqv" binary
* operation. unopa and unopb unravel tokens of this form.
*
* When a N_Unop node is encountered, unopa is called to emit the necessary
* number of "pnull" operations to receive the intermediate results. This
* amounts to a pnull for each operation.
*/
static void unopa(op,t)
int op;
nodeptr t;
{
switch (op) {
case NEQUIV: /* unary ~ and three = operators */
emit("pnull");
case SNE: /* unary ~ and two = operators */
case EQUIV: /* three unary = operators */
emit("pnull");
case NMNE: /* unary ~ and = operators */
case UNION: /* two unary + operators */
case DIFF: /* two unary - operators */
case SEQ: /* two unary = operators */
case INTER: /* two unary * operators */
emit("pnull");
case BACKSLASH: /* unary \ operator */
case BANG: /* unary ! operator */
case CARET: /* unary ^ operator */
case PLUS: /* unary + operator */
case TILDE: /* unary ~ operator */
case MINUS: /* unary - operator */
case NMEQ: /* unary = operator */
case STAR: /* unary * operator */
case QMARK: /* unary ? operator */
case SLASH: /* unary / operator */
case DOT: /* unary . operator */
emit("pnull");
break;
default:
tsyserr("unopa: undefined unary operator");
}
}
/*
* unopb is the back-end code emitter for unary operators. It emits
* the operations represented by the token op. For tokens representing
* a single operator, the name of the operator is emitted. For tokens
* representing a sequence of operators, recursive calls are used. In
* such a case, the operator sequence is "scanned" from right to left
* and unopb is called with the token for the appropriate operation.
*
* For example, consider the sequence of calls and code emission for "~===":
* unopb(NEQUIV) ~===
* unopb(NMEQ) =
* emits "tabmat"
* unopb(NMEQ) =
* emits "tabmat"
* unopb(NMEQ) =
* emits "tabmat"
* emits "compl"
*/
static void unopb(op)
int op;
{
register char *name;
switch (op) {
case DOT: /* unary . operator */
name = "value";
break;
case BACKSLASH: /* unary \ operator */
name = "nonnull";
break;
case BANG: /* unary ! operator */
name = "bang";
break;
case CARET: /* unary ^ operator */
name = "refresh";
break;
case UNION: /* two unary + operators */
unopb(PLUS);
case PLUS: /* unary + operator */
name = "number";
break;
case NEQUIV: /* unary ~ and three = operators */
unopb(NMEQ);
case SNE: /* unary ~ and two = operators */
unopb(NMEQ);
case NMNE: /* unary ~ and = operators */
unopb(NMEQ);
case TILDE: /* unary ~ operator (cset compl) */
name = "compl";
break;
case DIFF: /* two unary - operators */
unopb(MINUS);
case MINUS: /* unary - operator */
name = "neg";
break;
case EQUIV: /* three unary = operators */
unopb(NMEQ);
case SEQ: /* two unary = operators */
unopb(NMEQ);
case NMEQ: /* unary = operator */
name = "tabmat";
break;
case INTER: /* two unary * operators */
unopb(STAR);
case STAR: /* unary * operator */
name = "size";
break;
case QMARK: /* unary ? operator */
name = "random";
break;
case SLASH: /* unary / operator */
name = "null";
break;
default:
emitn("?unop", op);
tsyserr("unopb: undefined unary operator");
}
emit(name);
}
/*
* emitfile(n) emits "filen" directives for node n's source location.
* emitline(n) emits "line" and possibly "colm" directives.
* setloc(n) does both.
* A directive is only emitted if the corresponding value
* has changed since the previous call.
*
*/
static char *lastfiln = NULL;
static int lastlin = 0;
static void setloc(n)
nodeptr n;
{
emitfile(n);
emitline(n);
}
static void emitfile(n)
nodeptr n;
{
if ((n != NULL) &&
(TType(n) != N_Empty) &&
(File(n) != NULL) &&
(lastfiln == NULL || strcmp(File(n), lastfiln) != 0)) {
lastfiln = File(n);
emits("filen", lastfiln);
}
}
static void emitline(n)
nodeptr n;
{
#ifdef SrcColumnInfo
/*
* if either line or column has changed, emit location information
*/
if (((Col(n) << 16) + Line(n)) != lastlin) {
lastlin = (Col(n) << 16) + Line(n);
emitn("line",Line(n));
emitn("colm",Col(n));
}
#else /* SrcColumnInfo */
/*
* if line has changed, emit line information
*/
if (Line(n) != lastlin) {
lastlin = Line(n);
emitn("line", lastlin);
}
#endif /* SrcColumnInfo */
}
#ifdef MultipleRuns
/*
* Reinitialize last file name and line number for repeated runs.
*/
void tcodeinit()
{
lastfiln = NULL;
#ifdef EventMon
lastcol = 0;
#endif /* EventMon */
}
#endif /* Multiple Runs */
/*
* The emit* routines output ucode to codefile. The various routines are:
*
* emitlab(l) - emit "lab" instruction for label l.
* emit(s) - emit instruction s.
* emitl(s,a) - emit instruction s with reference to label a.
* emitn(s,n) - emit instruction s with numeric argument a.
* emits(s,a) - emit instruction s with string argument a.
*/
static void emitlab(l)
int l;
{
writecheck(fprintf(codefile, "lab L%d\n", l));
}
static void emit(s)
char *s;
{
writecheck(fprintf(codefile, "\t%s\n", s));
}
static void emitl(s, a)
char *s;
int a;
{
writecheck(fprintf(codefile, "\t%s\tL%d\n", s, a));
}
static void emitn(s, a)
char *s;
int a;
{
writecheck(fprintf(codefile, "\t%s\t%d\n", s, a));
}
static void emits(s, a)
char *s, *a;
{
writecheck(fprintf(codefile, "\t%s\t%s\n", s, a));
}
/*
* alclab allocates n labels and returns the first. For the interpreter,
* labels are restarted at 1 for each procedure, while in the compiler,
* they start at 1 and increase throughout the entire compilation.
*/
static int alclab(n)
int n;
{
register int lab;
lab = nextlab;
nextlab += n;
return lab;
}