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SRI_NIC_PERM_FS_1_19910112
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kcc-4/kcc/ccgen1.c
There are 8 other files named ccgen1.c in the archive. Click here to see a list.
/* CCGEN1.C - Generate code for parse-tree statement execution
**
** All changes after version 112 (8/8/85), unless otherwise specified, are
** Copyright 1985, 1986 by Ken Harrenstien, SRI International.
*/
/* [SRI-NIC]SS:<C.KCC.CC>CCGEN1.C.133, 17-Dec-85 07:59:25, Edit by KLH */
/* Rationalized names of constants and structures */
/* [SRI-NIC]SS:<C.KCC.CC>CCGEN1.C.117, 13-Dec-85 11:10:14, Edit by KLH */
/* Fix up code9 calls to provide a double as value */
/* [SRI-NIC]SS:<C.KCC.CC>CCGEN1.C.115, 12-Dec-85 13:49:19, Edit by IAN */
/* Fix optimized IF (1) and IF (0) not to deposit bogus never-reached code */
/* <KCC.CC>CCGEN1.C.111, 8-Aug-85 10:11:41, Edit by KRONJ */
/* Fix tail recursion to variable functions */
/* <KCC.CC>CCGEN1.C.107, 12-Jul-85 15:43:06, Edit by KRONJ */
/* Should be safe now not to skip in glogical() */
/* <KCC.CC>CCGEN1.C.92, 28-May-85 14:02:40, Edit by KRONJ */
/* Fix increment to use P_AOS instead of obsolete INC */
/* <KCC.CC>CCGEN1.C.85, 21-May-85 16:16:07, Edit by KRONJ */
/* ++ for floating point */
/* <KCC.CC>CCGEN1.C.84, 20-May-85 17:03:20, Edit by KRONJ */
/* Count spushes for that and gident() calling same routine */
/* <KCC.CC>CCGEN1.C.81, 20-May-85 16:50:59, Edit by KRONJ */
/* Make deref of struct ptr work for multi-word struct */
/* <KCC.CC>CCGEN1.C.75, 17-Mar-85 13:48:35, Edit by KRONJ */
/* Try doing tail recursion in gcall() rather than greturn() */
/* <KCC.CC>CCGEN1.C.53, 11-Mar-85 11:24:49, Edit by KRONJ */
/* Extract members from stacked structs */
/* <KCC.CC>CCGEN1.C.49, 11-Mar-85 09:12:46, Edit by KRONJ */
/* Clean up struct assignment */
/* <KCC.CC>CCGEN1.C.47, 10-Mar-85 11:15:38, Edit by KRONJ */
/* Fix *"x" - was losing the fact that "x" is a char ptr */
/* <KCC.CC>CCGEN1.C.44, 9-Mar-85 16:00:49, Edit by KRONJ */
/* Allow null terminated comma lists of fn args */
/* <KCC.CC>CCGEN1.C.42, 9-Mar-85 10:54:21, Edit by KRONJ */
/* reinstall SC_SCOPE */
/* <KCC.CC>CCGEN1.C.39, 24-Feb-85 21:59:40, Edit by SATZ */
/* Remove SC_SCOPE */
/* <KCC.CC>CCGEN1.C.38, 14-Jan-85 11:16:20, Edit by SATZ */
/* handle two word structures right */
/* <KCC.CC>CCGEN1.C.37, 13-Jan-85 20:15:48, Edit by SATZ */
/* Rewrite to make a little neater */
/* <KCC.CC>CCGEN1.C.36, 13-Jan-85 20:01:13, Edit by SATZ */
/* Second stab: try to push doubles or two word structs onto the */
/* stack; remember to optimize */
/* stack if they are used as function/procedure arguments */
/* <KCC.CC>CCGEN1.C.33, 11-Jan-85 16:29:50, Edit by SATZ */
/* First stab at fixing double arguments to procedures */
/* <KCC.CC>CCGEN1.C.26, 3-Jan-85 17:56:34, Edit by KRONJ */
/* struct assignment and function args */
/* <KCC.CC>CCGEN1.C.24, 2-Jan-85 15:21:03, Edit by KRONJ */
/* stack strings for output in litstrings */
/* <KCC.CC>CCGEN1.C.20, 2-Jan-85 13:17:48, Edit by KRONJ */
/* non-global struct members */
/* <KCC.CC>CCGEN1.C.19, 29-Dec-84 13:01:52, Edit by KRONJ */
/* generate condition for if with null body */
/* SCORE:<KCC.CC>CCGEN1.C.8, 29-Jul-84 12:02:03, Edit by KRONJ */
/* glogical() knows to put result in return val */
/* SCORE:<KCC.CC>CCGEN1.C.6, 24-Jul-84 17:38:35, Edit by KRONJ */
/* undo failed changereg() from findconst() in gconst() */
/* SCORE:<KCC.CC>CCGEN1.C.4, 18-Jul-84 15:43:24, Edit by KRONJ */
/* uncalled function identifier returns address not first instruction */
/* SCORE:<KCC.CC>CCGEN1.C.2, 16-Jul-84 12:25:09, Edit by KRONJ */
/* clean up optimizations in greturn() */
/* SCORE:<KCC.CC>CC82.C.49, 2-Jul-84 12:27:04, Edit by KRONJ */
/* undo failed changereg made by foldmove before it propagates */
/* SCORE:<KCC.CC>CC82.C.5, 12-May-84 22:36:53, Edit by KRONJ */
/* clean up RETURN */
/* SCORE:<KCC.CC>CC82.C.2, 5-May-84 13:41:50, Edit by KRONJ */
/* improved code for logical NOT */
/* cc82.c -- Code generator TOPS-20 (contd) (C) 1981 K. Chen */
/* Statement code generator */
#include "cc.h"
#include "ccgen.h"
/* Imported functions */
extern VREG *genexpr(); /* CCGEN2 for expressions */
extern void genxrelease(); /* CCGEN2 for discarded expressions */
extern void gswitch(); /* CCGSWI for switch statement */
/* Exported functions defined here */
void genstmt();
/* Internal functions */
static void genadata();
static void gdo(), gfor(), gif(), gwhile(), greturn();
static int labck();
/* ------------------------------------- */
/* generate code for statement */
/* ------------------------------------- */
void
genstmt(n)
NODE *n;
{
NODE *rv;
VREG *r;
if (n == NULL) return;
switch (n->Nop) {
case N_STATEMENT:
{ NODE *beg, *next;
if (n->Nleft && n->Nleft->Nop == N_DATA) { /* Check for auto inits */
genadata(n->Nleft); /* Yep, do them */
n = n->Nright; /* then move on to real statements */
}
for(beg = n; n != NULL; n = n->Nright) {
if(n->Nop != N_STATEMENT)
error(EINTNOD,"bad statement", n);
if(n->Nleft == NULL) continue;
/* Check out following stmt for possible optimizations */
if(n->Nright && (next = n->Nright->Nleft) && optgen) {
switch(next->Nop) {
/* Hack to encourage tail recursion */
case Q_RETURN: /* If next will be RETURN */
if(next->Nright == NULL) { /* and has no return val */
NODE *v, *laststmt(); /* Then try to optimize */
if((v = laststmt(n->Nleft)) && v->Nop == N_FNCALL)
v->Nflag |= NF_RETEXPR;
}
break;
/* If next stmt is a GOTO, ensure that any jumps
* within current stmt to end of stmt will
* instead go directly to object of the GOTO.
* Avoids jumping to jumps...
* We do a similar hack for BREAK and CONTINUE,
* which are similar to GOTOs except that their
* destination is kept in variables global to the
* code generation routines.
*/
case Q_CASE: /* Not sure about this one yet */
case N_LABEL:
case Q_GOTO:
n->Nleft->Nendlab = next->Nxfsym;
break;
case Q_BREAK:
n->Nleft->Nendlab = brklabel;
break;
case Q_CONTINUE:
n->Nleft->Nendlab = looplabel;
break;
} /* end of Nop switch */
} /* end of next-stmt check */
/* Optimize label usage */
if(n->Nright == NULL /* If this is last stmt in list */
&& optgen)
n->Nleft->Nendlab = beg->Nendlab; /* Copy from 1st */
genstmt(n->Nleft);
}
break;
} /* end of N_STATEMENT case block */
case Q_CASE:
emitlabel (n->Nxfsym); /* send forward label */
n->Nleft->Nendlab = n->Nendlab; /* propagate end label */
genstmt (n->Nleft); /* finish rest of body */
break;
case N_LABEL:
emitgoto (n->Nxfsym); /* send goto label */
n->Nleft->Nendlab = n->Nendlab; /* propagate end label */
genstmt (n->Nleft); /* finish rest of body */
break;
case Q_BREAK: code6(P_JRST, 0, brklabel); break;
case Q_GOTO: code6(P_JRST, 0, n->Nxfsym); break;
case Q_CONTINUE: code6(P_JRST, 0, looplabel); break;
case Q_DO: gdo(n); break;
case Q_FOR: gfor(n); break;
case Q_IF: gif(n); break;
case Q_RETURN: greturn(n); break;
case Q_SWITCH: gswitch(n); break;
case Q_WHILE: gwhile(n); break;
case N_EXPRLIST: /* Same as expression stmt */
default: /* None of above, assume expression stmt */
genxrelease(n); /* Generate it and flush any result */
break;
}
}
/* Hack for statement optimization. Find last statement in list. */
static NODE *
laststmt(n)
NODE *n;
{
while(n && n->Nop == N_STATEMENT) {
while(n->Nright) n = n->Nright;
n = n->Nleft;
}
return(n);
}
/* GENADATA - Generate auto data initializations
** Should be called only for N_DATA nodes.
*/
static void
genadata(n)
NODE *n;
{
VREG *r;
if (n->Nop != N_DATA) {
error(EINTNOD,"node not N_DATA", n);
return;
}
for (; n && n->Nop == N_DATA; n = n->Nright) {
if (n->Nleft != NULL && n->Nleft->Nright != NULL) {
/* Have an N_IZ node with initializer, process it
** by turning the N_IZ into a Q_ASGN expression. Note the
** C type of the expression needs to be set (from the Q_IDENT).
*/
n->Nleft->Nop = Q_ASGN; /* Turn N_IZ into Q_ASGN */
n->Nleft->Ntype = n->Nleft->Nleft->Ntype; /* Set up type */
genxrelease(n->Nleft); /* Generate code, ignore value */
}
}
}
/* ---------------------- */
/* if statement */
/* ---------------------- */
static void
gif(n)
NODE *n;
{
SYMBOL *true, *false;
NODE *nthen, *nelse, *body, *l;
body = n->Nright;
nthen = body->Nleft;
nelse = body->Nright;
l = n->Nleft;
/* optimize if to a jump */
if (nelse == NULL) {
if (nthen == NULL) { /* no body of either kind?? */
genxrelease(l); /* yes, just produce condition */
return; /* and return */
} else if (optgen) switch (nthen->Nop) {
case Q_BREAK:
l->Nendlab = n->Nendlab;
gboolean(l, brklabel, 1);
return;
case Q_GOTO:
l->Nendlab = n->Nendlab;
gboolean(l, nthen->Nxfsym, 1);
return;
case Q_CONTINUE:
l->Nendlab = n->Nendlab;
gboolean(l, looplabel, 1);
return;
}
}
/* Try to optimize when conditional expression is a constant.
** We have to be careful about flushing the then/else clauses because
** control could jump into them using either case or goto labels.
** Hence the labchk() to see whether the parse tree contains such labels...
*/
if (l->Nop == N_ICONST && optgen) { /* If cond is constant */
if (l->Niconst && nthen && !labchk(nelse)) { /* if (1) */
nthen->Nendlab = n->Nendlab;
genstmt(nthen);
return;
}
if (!l->Niconst && nelse && !labchk(nthen)) { /* if (0) */
nelse->Nendlab = n->Nendlab;
genstmt(nelse);
return;
}
}
/* do unoptimized if statement - first get exit label */
true = ((n->Nendlab == NULL)? newlabel(1) : n->Nendlab);
/* then emit code for test and clauses */
if (nthen) {
if (nelse == NULL) false = true;
else switch (nelse->Nop) {
case Q_GOTO:
false = nelse->Nxfsym;
nelse = NULL;
break;
case Q_CONTINUE:
false = looplabel;
nelse = NULL;
break;
case Q_BREAK:
false = brklabel;
nelse = NULL;
break;
default:
false = newlabel (1);
}
switch(nthen->Nop) { /* we could invert the boolean here, */
case Q_GOTO: /* but instead we merely set label */
case N_LABEL: /* at the end of the condition. */
case Q_CASE: /* fixes gotos in both clauses. */
l->Nendlab = nthen->Nxfsym;
break;
case Q_CONTINUE:
l->Nendlab = looplabel;
break;
case Q_BREAK:
l->Nendlab = brklabel;
}
gboolean(l, false, 0);
nthen->Nendlab = true;
genstmt(nthen);
if (nelse) {
code6(P_JRST, 0, true);
emitlabel (false);
nelse->Nendlab = true;
genstmt(nelse);
}
} else if (nelse) {
gboolean(l, true, 1);
nelse->Nendlab = true;
genstmt(nelse);
}
/* then emit exit label */
if (!n->Nendlab) emitlabel (true); /* emit exit label */
}
/* LABCHK - returns true if parse tree contains any labels.
*/
static int
labchk(n)
NODE *n;
{
if (n == NULL) return 0;
switch (n->Nop) {
case Q_CASE: /* These three are all labels */
case N_LABEL:
case Q_DEFAULT:
return 1;
case N_STATEMENT: /* Compound statement, scan it. */
if (n->Nleft && n->Nleft->Nop == N_DATA) /* Skip auto inits */
n = n->Nright; /* move on to real statements */
for(; n != NULL; n = n->Nright) {
if(n->Nop != N_STATEMENT)
error(EINTNOD,"bad statement", n);
if(n->Nleft && labchk(n->Nleft))
return 1;
}
return 0;
case Q_IF: /* Has two substatements */
return labchk(n->Nright->Nleft) || labchk(n->Nright->Nright);
case Q_DO: /* Standard substatements */
case Q_FOR:
case Q_SWITCH:
case Q_WHILE:
return labchk(n->Nright);
case Q_BREAK: /* Not labels and no substatements */
case Q_GOTO:
case Q_CONTINUE:
case Q_RETURN:
case N_EXPRLIST: /* Same as expression stmt */
default: /* None of above, assume expression stmt */
return 0;
}
}
/* ------------------------- */
/* while statement */
/* ------------------------- */
static void
gwhile(n)
NODE *n;
{
SYMBOL *saveb, *savel;
/* ok, we do, so we need to make a label for the top */
savel = looplabel;
looplabel = newlabel (0);
/* now, see if there is a body or just the test */
if (n->Nright == NULL) {
n->Nleft->Nendlab = n->Nendlab; /* propagate exit point */
gboolean(n->Nleft, looplabel, 1); /* no body, just test */
} else {
saveb = brklabel; /* full body, need another label */
brklabel = (n->Nendlab != NULL)? n->Nendlab : newlabel (1);
n->Nright->Nendlab = looplabel; /* exit from body is to loop top */
gboolean(n->Nleft, brklabel, 0); /* first the test, if any */
genstmt(n->Nright); /* then the actual body */
code6(P_JRST, 0, looplabel); /* body jumps back to test */
if (n->Nendlab == NULL) emitlabel(brklabel); /* emit end label */
brklabel = saveb; /* restore label for outer loop */
}
/* in either case we need to restore the outer loop top label */
freelabel (looplabel);
looplabel = savel; /* fix the label */
}
/* ---------------------- */
/* do statement */
/* ---------------------- */
static void
gdo(n)
NODE *n;
{
SYMBOL *saveb, *savel, *toplabel;
toplabel = newlabel (0);
saveb = brklabel;
brklabel = (n->Nendlab != NULL) ? n->Nendlab : newlabel (1);
if (n->Nright) {
savel = looplabel;
n->Nright->Nendlab = looplabel = newlabel (1);
genstmt(n->Nright);
emitlabel (looplabel);
looplabel = savel; /* restore outer loop label */
}
if ((n->Nleft->Nop) != N_ICONST) {
n->Nleft->Nendlab = brklabel;
gboolean(n->Nleft, toplabel, 1);
} else if (n->Nleft->Niconst) code6(P_JRST, 0, toplabel);
if (n->Nendlab == NULL) emitlabel (brklabel);
brklabel = saveb; /* restore for outer breaks */
freelabel (toplabel); /* no more use for this one */
}
/* ----------------------- */
/* for statement */
/* ----------------------- */
static void
gfor(n)
NODE *n;
{
NODE *cond, *body, *init, *incr;
SYMBOL *saveb, *savel, *toplabel;
int endtest; /* safe to move test to end of loop */
cond = n->Nleft;
body = n->Nright;
incr = cond->Nright->Nleft;
cond = cond->Nleft;
init = cond->Nleft;
cond = cond->Nright;
if (init) genxrelease(init);
toplabel = newlabel (0);
endtest = ((body == NULL && incr == NULL) || istrue(cond, init));
saveb = brklabel;
brklabel = (n->Nendlab != NULL)? n->Nendlab : newlabel (1);
savel = looplabel; /* remember prev outer label */
looplabel = (body == NULL || (incr == NULL && (cond == NULL || !endtest)))?
toplabel : newlabel (1);
if (!endtest) gboolean(cond, brklabel, 0); /* test at start of loop */
if (body != NULL) {
body->Nendlab = looplabel;
genstmt (body);
if (looplabel != toplabel) emitlabel (looplabel);
}
if (incr != NULL) {
if (cond == NULL || !endtest) incr->Nendlab = toplabel;
genxrelease(incr);
}
if (cond == NULL || !endtest) code6(P_JRST, 0, toplabel); /* just loop */
else { /* test comes at end of loop */
cond->Nendlab = brklabel; /* set end label for it */
gboolean(cond,toplabel,1); /* conditional loop */
}
if (n->Nendlab == NULL) emitlabel (brklabel);
brklabel = saveb; /* restore old break label */
looplabel = savel; /* restore outer loop continuation */
freelabel (toplabel); /* don't need top label any more */
}
/* -------------------------- */
/* return statement */
/* -------------------------- */
static void
greturn(n)
NODE *n;
{
int siz;
VREG *r;
if (safejump(previous)) return; /* if in dead code, do nothing */
if ((n = n->Nright) != NULL) { /* if returning val, set it */
n->Nflag |= NF_RETEXPR; /* this is to be return value */
siz = sizetype(n->Ntype);
if (n->Ntype->Tspec == TS_ARRAY) { /* Just in case */
error(EINT,"returning array type");
return;
}
switch (siz) {
case 1:
r = genexpr (n);
if (safejump(previous)) return;
code0 (P_MOVE, R_RETVAL, r); /* don't need to worry about */
break; /* register allocation, just do it */
case 2:
r = genexpr (n);
if (safejump(previous)) return;
code0 (P_DMOVE, R_RETVAL, r);
break;
default:
r = getreg();
code13(P_MOVE, r, -1 - stackoffset); /* Get 1st arg addr */
code4(P_MOVE, r, r); /* Get ptr to place to return struct */
code4s(P_SMOVE, r, genexpr(n), 0, siz); /* Return it */
release(r);
}
}
if (optobj) killstack(); /* get rid of spurious P_MOVEMs */
code8 (P_ADJSP, R_SP, - stackoffset); /* flush local vars from stk */
code5 (P_POPJ, R_SP); /* emit the return */
}