V7M/src/cmd/mip/reader.c
# include "mfile2"
/* some storage declarations */
# ifndef ONEPASS
NODE node[TREESZ];
char filename[100] = ""; /* the name of the file */
int ftnno; /* number of current function */
int lineno;
# else
# define NOMAIN
#endif
int nrecur;
int lflag;
int edebug = 0;
int xdebug = 0;
int udebug = 0;
OFFSZ tmpoff; /* offset for first temporary, in bits for current block */
OFFSZ maxoff; /* maximum temporary offset over all blocks in current ftn, in bits */
int maxtreg;
NODE *stotree;
int stocook;
OFFSZ baseoff = 0;
OFFSZ maxtemp = 0;
p2init( argc, argv ) char *argv[];{
/* set the values of the pass 2 arguments */
register int c;
register char *cp;
register files;
allo0(); /* free all regs */
files = 0;
for( c=1; c<argc; ++c ){
if( *(cp=argv[c]) == '-' ){
while( *++cp ){
switch( *cp ){
case 'X': /* pass1 flags */
while( *++cp ) { /* VOID */ }
--cp;
break;
case 'l': /* linenos */
++lflag;
break;
case 'e': /* expressions */
++edebug;
break;
case 'o': /* orders */
++odebug;
break;
case 'r': /* register allocation */
++rdebug;
break;
case 'a': /* rallo */
++radebug;
break;
case 't': /* ttype calls */
++tdebug;
break;
case 's': /* shapes */
++sdebug;
break;
case 'u': /* Sethi-Ullman testing (machine dependent) */
++udebug;
break;
case 'x': /* general machine-dependent debugging flag */
++xdebug;
break;
default:
cerror( "bad option: %c", *cp );
}
}
}
else files = 1; /* assumed to be a filename */
}
mkdope();
setrew();
return( files );
}
# ifndef NOMAIN
mainp2( argc, argv ) char *argv[]; {
register files;
register temp;
register c;
register char *cp;
register NODE *p;
files = p2init( argc, argv );
tinit();
reread:
if( files ){
while( files < argc && argv[files][0] == '-' ) {
++files;
}
if( files > argc ) return( nerrors );
freopen( argv[files], "r", stdin );
}
while( (c=getchar()) > 0 ) switch( c ){
case ')':
/* copy line unchanged */
while( (c=getchar()) > 0 ){
PUTCHAR(c);
if( c == '\n' ) break;
}
continue;
case '[':
/* beginning of a block */
temp = rdin(10); /* ftnno */
tmpoff = baseoff = rdin(10); /* autooff for block gives max offset of autos in block */
maxtreg = rdin(10);
if( getchar() != '\n' ) cerror( "intermediate file format error");
if( temp != ftnno ){ /* beginning of function */
maxoff = baseoff;
ftnno = temp;
maxtemp = 0;
}
else {
if( baseoff > maxoff ) maxoff = baseoff;
/* maxoff at end of ftn is max of autos and temps
over all blocks in the function */
}
setregs();
continue;
case ']': /* end of block */
SETOFF( maxoff, ALSTACK );
eobl2();
while( (c=getchar()) != '\n' ){
if( c <= 0 ) cerror( "intermediate file format eof" );
}
continue;
case '.':
/* compile code for an expression */
lineno = rdin( 10 );
for( cp=filename; (*cp=getchar()) != '\n'; ++cp ) ; /* VOID, reads filename */
*cp = '\0';
if( lflag ) lineid( lineno, filename );
tmpoff = baseoff; /* expression at top level reuses temps */
p = eread();
if( edebug ) fwalk( p, eprint, 0 );
# ifdef MYREADER
MYREADER(p); /* do your own laundering of the input */
# endif
nrecur = 0;
delay( p ); /* expression statement throws out results */
reclaim( p, RNULL, 0 );
allchk();
tcheck();
continue;
default:
cerror( "intermediate file format error" );
}
/* EOF */
if( files ) goto reread;
return(nerrors);
}
# endif
# ifdef ONEPASS
p2compile( p ) NODE *p; {
if( lflag ) lineid( lineno, filename );
tmpoff = baseoff; /* expression at top level reuses temps */
/* generate code for the tree p */
if( edebug ) fwalk( p, eprint, 0 );
# ifdef MYREADER
MYREADER(p); /* do your own laundering of the input */
# endif
nrecur = 0;
delay( p ); /* do the code generation */
reclaim( p, RNULL, 0 );
allchk();
/* can't do tcheck here; some stuff (e.g., attributes) may be around from first pass */
/* first pass will do it... */
}
p2bbeg( aoff, myreg ) {
static int myftn = -1;
tmpoff = baseoff = aoff;
maxtreg = myreg;
if( myftn != ftnno ){ /* beginning of function */
maxoff = baseoff;
myftn = ftnno;
maxtemp = 0;
}
else {
if( baseoff > maxoff ) maxoff = baseoff;
/* maxoff at end of ftn is max of autos and temps over all blocks */
}
setregs();
}
p2bend(){
SETOFF( maxoff, ALSTACK );
eobl2();
}
# endif
NODE *deltrees[DELAYS];
int deli;
delay( p ) register NODE *p; {
/* look in all legal places for COMOP's and ++ and -- ops to delay */
/* note; don't delay ++ and -- within calls or things like
/* getchar (in their macro forms) will start behaving strangely */
register i;
/* look for visible COMOPS, and rewrite repeatedly */
while( delay1( p ) ) { /* VOID */ }
/* look for visible, delayable ++ and -- */
deli = 0;
delay2( p );
codgen( p, FOREFF ); /* do what is left */
for( i = 0; i<deli; ++i ) codgen( deltrees[i], FOREFF ); /* do the rest */
}
delay1( p ) register NODE *p; { /* look for COMOPS */
register o, ty;
o = p->op;
ty = optype( o );
if( ty == LTYPE ) return( 0 );
else if( ty == UTYPE ) return( delay1( p->left ) );
switch( o ){
case QUEST:
case ANDAND:
case OROR:
/* don't look on RHS */
return( delay1(p->left ) );
case COMOP: /* the meat of the routine */
delay( p->left ); /* completely evaluate the LHS */
/* rewrite the COMOP */
{ register NODE *q;
q = p->right;
ncopy( p, p->right );
q->op = FREE;
}
return( 1 );
}
return( delay1(p->left) || delay1(p->right ) );
}
delay2( p ) register NODE *p; {
/* look for delayable ++ and -- operators */
register o, ty;
o = p->op;
ty = optype( o );
switch( o ){
case NOT:
case QUEST:
case ANDAND:
case OROR:
case CALL:
case UNARY CALL:
case STCALL:
case UNARY STCALL:
case FORTCALL:
case UNARY FORTCALL:
case COMOP:
case CBRANCH:
/* for the moment, don7t delay past a conditional context, or
/* inside of a call */
return;
case INCR:
case DECR:
if( deltest( p ) ){
if( deli < DELAYS ){
register NODE *q;
deltrees[deli++] = tcopy(p);
q = p->left;
p->right->op = FREE; /* zap constant */
ncopy( p, q );
q->op = FREE;
return;
}
}
}
if( ty == BITYPE ) delay2( p->right );
if( ty != LTYPE ) delay2( p->left );
}
codgen( p, cookie ) NODE *p; {
/* generate the code for p;
order may call codgen recursively */
/* cookie is used to describe the context */
for(;;){
canon(p); /* creats OREG from * if possible and does sucomp */
stotree = NIL;
if( edebug ){
printf( "store called on:\n" );
fwalk( p, eprint, 0 );
}
store(p);
if( stotree==NIL ) break;
/* because it's minimal, can do w.o. stores */
order( stotree, stocook );
}
order( p, cookie );
}
char *cnames[] = {
"SANY",
"SAREG",
"STAREG",
"SBREG",
"STBREG",
"SCC",
"SNAME",
"SCON",
"SFLD",
"SOREG",
"STARNM",
"STARREG",
"INTEMP",
"FORARG",
"SWADD",
0,
};
prcook( cookie ){
/* print a nice-looking description of cookie */
int i, flag;
if( cookie & SPECIAL ){
if( cookie == SZERO ) printf( "SZERO" );
else if( cookie == SONE ) printf( "SONE" );
else if( cookie == SMONE ) printf( "SMONE" );
else printf( "SPECIAL+%d", cookie & ~SPECIAL );
return;
}
flag = 0;
for( i=0; cnames[i]; ++i ){
if( cookie & (1<<i) ){
if( flag ) printf( "|" );
++flag;
printf( cnames[i] );
}
}
}
int odebug = 0;
order(p,cook) NODE *p; {
register o, ty, m;
int m1;
int cookie;
NODE *p1, *p2;
/* by this time, p should be able to be generated without stores;
the only question is how */
again:
cookie = cook;
rcount();
canon(p);
rallo( p, p->rall );
if( odebug ){
printf( "order( %o, ", p );
prcook( cookie );
printf( " )\n" );
fwalk( p, eprint, 0 );
}
o = p->op;
ty = optype(o);
/* first of all, for most ops, see if it is in the table */
/* look for ops */
switch( m = p->op ){
default:
/* look for op in table */
for(;;){
if( (m = match( p, cookie ) ) == MDONE ) goto cleanup;
else if( m == MNOPE ){
if( !(cookie = nextcook( p, cookie ) ) ) goto nomat;
continue;
}
else break;
}
break;
case COMOP:
case FORCE:
case CBRANCH:
case QUEST:
case ANDAND:
case OROR:
case NOT:
case UNARY CALL:
case CALL:
case UNARY STCALL:
case STCALL:
case UNARY FORTCALL:
case FORTCALL:
/* don't even go near the table... */
;
}
/* get here to do rewriting if no match or
fall through from above for hard ops */
p1 = p->left;
if( ty == BITYPE ) p2 = p->right;
else p2 = NIL;
if( odebug ){
printf( "order( %o, ", p );
prcook( cook );
printf( " ), cookie " );
prcook( cookie );
printf( ", rewrite %s\n", opst[m] );
}
switch( m ){
default:
nomat:
cerror( "no table entry for op %s", opst[p->op] );
case COMOP:
codgen( p1, FOREFF );
p2->rall = p->rall;
codgen( p2, cookie );
ncopy( p, p2 );
p2->op = FREE;
goto cleanup;
case FORCE:
/* recurse, letting the work be done by rallo */
p = p->left;
cook = INTAREG|INTBREG;
goto again;
case CBRANCH:
o = p2->lval;
cbranch( p1, -1, o );
p2->op = FREE;
p->op = FREE;
return;
case QUEST:
cbranch( p1, -1, m=getlab() );
p2->left->rall = p->rall;
codgen( p2->left, INTAREG|INTBREG );
/* force right to compute result into same reg used by left */
p2->right->rall = p2->left->rval|MUSTDO;
reclaim( p2->left, RNULL, 0 );
cbgen( 0, m1 = getlab(), 'I' );
deflab( m );
codgen( p2->right, INTAREG|INTBREG );
deflab( m1 );
p->op = REG; /* set up node describing result */
p->lval = 0;
p->rval = p2->right->rval;
p->type = p2->right->type;
tfree( p2->right );
p2->op = FREE;
goto cleanup;
case ANDAND:
case OROR:
case NOT: /* logical operators */
/* if here, must be a logical operator for 0-1 value */
cbranch( p, -1, m=getlab() );
p->op = CCODES;
p->label = m;
order( p, INTAREG );
goto cleanup;
case FLD: /* fields of funny type */
if ( p1->op == UNARY MUL ){
offstar( p1->left );
goto again;
}
case UNARY MINUS:
order( p1, INBREG|INAREG );
goto again;
case NAME:
/* all leaves end up here ... */
if( o == REG ) goto nomat;
order( p, INTAREG|INTBREG );
goto again;
case INIT:
uerror( "illegal initialization" );
return;
case UNARY FORTCALL:
p->right = NIL;
case FORTCALL:
o = p->op = UNARY FORTCALL;
if( genfcall( p, cookie ) ) goto nomat;
goto cleanup;
case UNARY CALL:
p->right = NIL;
case CALL:
o = p->op = UNARY CALL;
if( gencall( p, cookie ) ) goto nomat;
goto cleanup;
case UNARY STCALL:
p->right = NIL;
case STCALL:
o = p->op = UNARY STCALL;
if( genscall( p, cookie ) ) goto nomat;
goto cleanup;
/* if arguments are passed in register, care must be taken that reclaim
/* not throw away the register which now has the result... */
case UNARY MUL:
if( cook == FOREFF ){
/* do nothing */
order( p->left, FOREFF );
p->op = FREE;
return;
}
offstar( p->left );
goto again;
case INCR: /* INCR and DECR */
if( setincr(p) ) goto again;
/* x++ becomes (x += 1) -1; */
if( cook & FOREFF ){ /* result not needed so inc or dec and be done with it */
/* x++ => x += 1 */
p->op = (p->op==INCR)?ASG PLUS:ASG MINUS;
goto again;
}
p1 = tcopy(p);
reclaim( p->left, RNULL, 0 );
p->left = p1;
p1->op = (p->op==INCR)?ASG PLUS:ASG MINUS;
p->op = (p->op==INCR)?MINUS:PLUS;
goto again;
case STASG:
if( setstr( p ) ) goto again;
goto nomat;
case ASG PLUS: /* and other assignment ops */
if( setasop(p) ) goto again;
/* there are assumed to be no side effects in LHS */
p2 = tcopy(p);
p->op = ASSIGN;
reclaim( p->right, RNULL, 0 );
p->right = p2;
canon(p);
rallo( p, p->rall );
if( odebug ) fwalk( p, eprint, 0 );
order( p2->left, INTBREG|INTAREG );
order( p2, INTBREG|INTAREG );
goto again;
case ASSIGN:
if( setasg( p ) ) goto again;
goto nomat;
case BITYPE:
if( setbin( p ) ) goto again;
/* try to replace binary ops by =ops */
switch(o){
case PLUS:
case MINUS:
case MUL:
case DIV:
case MOD:
case AND:
case OR:
case ER:
case LS:
case RS:
p->op = ASG o;
goto again;
}
goto nomat;
}
cleanup:
/* if it is not yet in the right state, put it there */
if( cook & FOREFF ){
reclaim( p, RNULL, 0 );
return;
}
if( p->op==FREE ) return;
if( tshape( p, cook ) ) return;
if( (m=match(p,cook) ) == MDONE ) return;
/* we are in bad shape, try one last chance */
if( lastchance( p, cook ) ) goto again;
goto nomat;
}
int callflag;
int fregs;
store( p ) register NODE *p; {
/* find a subtree of p which should be stored */
register o, ty;
o = p->op;
ty = optype(o);
if( ty == LTYPE ) return;
switch( o ){
case UNARY CALL:
case UNARY FORTCALL:
case UNARY STCALL:
++callflag;
break;
case UNARY MUL:
if( asgop(p->left->op) ) stoasg( p->left, UNARY MUL );
break;
case CALL:
case FORTCALL:
case STCALL:
store( p->left );
stoarg( p->right, o );
++callflag;
return;
case COMOP:
markcall( p->right );
if( p->right->su > fregs ) SETSTO( p, INTEMP );
store( p->left );
return;
case ANDAND:
case OROR:
case QUEST:
markcall( p->right );
if( p->right->su > fregs ) SETSTO( p, INTEMP );
case CBRANCH: /* to prevent complicated expressions on the LHS from being stored */
case NOT:
constore( p->left );
return;
}
if( ty == UTYPE ){
store( p->left );
return;
}
if( asgop( p->right->op ) ) stoasg( p->right, o );
if( p->su>fregs ){ /* must store */
mkadrs( p ); /* set up stotree and stocook to subtree
that must be stored */
}
store( p->right );
store( p->left );
}
constore( p ) register NODE *p; {
/* store conditional expressions */
/* the point is, avoid storing expressions in conditional
conditional context, since the evaluation order is predetermined */
switch( p->op ) {
case ANDAND:
case OROR:
case QUEST:
markcall( p->right );
case NOT:
constore( p->left );
return;
}
store( p );
}
markcall( p ) register NODE *p; { /* mark off calls below the current node */
again:
switch( p->op ){
case UNARY CALL:
case UNARY STCALL:
case UNARY FORTCALL:
case CALL:
case STCALL:
case FORTCALL:
++callflag;
return;
}
switch( optype( p->op ) ){
case BITYPE:
markcall( p->right );
case UTYPE:
p = p->left;
/* eliminate recursion (aren't I clever...) */
goto again;
case LTYPE:
return;
}
}
stoarg( p, calltype ) register NODE *p; {
/* arrange to store the args */
if( p->op == CM ){
stoarg( p->left, calltype );
p = p->right ;
}
if( calltype == CALL ){
STOARG(p);
}
else if( calltype == STCALL ){
STOSTARG(p);
}
else {
STOFARG(p);
}
callflag = 0;
store(p);
# ifndef NESTCALLS
if( callflag ){ /* prevent two calls from being active at once */
SETSTO(p,INTEMP);
store(p); /* do again to preserve bottom up nature.... */
}
#endif
}
int negrel[] = { NE, EQ, GT, GE, LT, LE, UGT, UGE, ULT, ULE } ; /* negatives of relationals */
cbranch( p, true, false ) NODE *p; {
/* evaluate p for truth value, and branch to true or false
/* accordingly: label <0 means fall through */
register o, lab, flab, tlab;
lab = -1;
switch( o=p->op ){
case ULE:
case ULT:
case UGE:
case UGT:
case EQ:
case NE:
case LE:
case LT:
case GE:
case GT:
if( true < 0 ){
o = p->op = negrel[ o-EQ ];
true = false;
false = -1;
}
#ifndef NOOPT
if( p->right->op == ICON && p->right->lval == 0 && p->right->name[0] == '\0' ){
switch( o ){
case UGT:
case ULE:
o = p->op = (o==UGT)?NE:EQ;
case EQ:
case NE:
case LE:
case LT:
case GE:
case GT:
if( logop(p->left->op) ){
/* strange situation: e.g., (a!=0) == 0 */
/* must prevent reference to p->left->lable, so get 0/1 */
/* we could optimize, but why bother */
codgen( p->left, INAREG|INBREG );
}
codgen( p->left, FORCC );
cbgen( o, true, 'I' );
break;
case UGE:
cbgen( 0, true, 'I' ); /* unconditional branch */
case ULT:
; /* do nothing for LT */
}
}
else
#endif
{
p->label = true;
codgen( p, FORCC );
}
if( false>=0 ) cbgen( 0, false, 'I' );
reclaim( p, RNULL, 0 );
return;
case ANDAND:
lab = false<0 ? getlab() : false ;
cbranch( p->left, -1, lab );
cbranch( p->right, true, false );
if( false < 0 ) deflab( lab );
p->op = FREE;
return;
case OROR:
lab = true<0 ? getlab() : true;
cbranch( p->left, lab, -1 );
cbranch( p->right, true, false );
if( true < 0 ) deflab( lab );
p->op = FREE;
return;
case NOT:
cbranch( p->left, false, true );
p->op = FREE;
break;
case COMOP:
codgen( p->left, FOREFF );
p->op = FREE;
cbranch( p->right, true, false );
return;
case QUEST:
flab = false<0 ? getlab() : false;
tlab = true<0 ? getlab() : true;
cbranch( p->left, -1, lab = getlab() );
cbranch( p->right->left, tlab, flab );
deflab( lab );
cbranch( p->right->right, true, false );
if( true < 0 ) deflab( tlab);
if( false < 0 ) deflab( flab );
p->right->op = FREE;
p->op = FREE;
return;
case ICON:
if( p->type != FLOAT && p->type != DOUBLE ){
if( p->lval || p->name[0] ){
/* addresses of C objects are never 0 */
if( true>=0 ) cbgen( 0, true, 'I' );
}
else if( false>=0 ) cbgen( 0, false, 'I' );
p->op = FREE;
return;
}
/* fall through to default with other strange constants */
default:
/* get condition codes */
codgen( p, FORCC );
if( true >= 0 ) cbgen( NE, true, 'I' );
if( false >= 0 ) cbgen( true >= 0 ? 0 : EQ, false, 'I' );
reclaim( p, RNULL, 0 );
return;
}
}
rcount(){ /* count recursions */
if( ++nrecur > NRECUR ){
cerror( "expression causes compiler loop: try simplifying" );
}
}
eprint( p, down, a, b ) NODE *p; int *a, *b; {
*a = *b = down+1;
while( down >= 2 ){
printf( "\t" );
down -= 2;
}
if( down-- ) printf( " " );
printf( "%o) %s", p, opst[p->op] );
switch( p->op ) { /* special cases */
case REG:
printf( " %s", rnames[p->rval] );
break;
case ICON:
case NAME:
case OREG:
printf( " " );
adrput( p );
break;
case STCALL:
case UNARY STCALL:
case STARG:
case STASG:
printf( " size=%d", p->stsize );
printf( " align=%d", p->stalign );
break;
}
printf( ", " );
tprint( p->type );
printf( ", " );
if( p->rall == NOPREF ) printf( "NOPREF" );
else {
if( p->rall & MUSTDO ) printf( "MUSTDO " );
else printf( "PREF " );
printf( "%s", rnames[p->rall&~MUSTDO]);
}
printf( ", SU= %d\n", p->su );
}
# ifndef NOMAIN
NODE *
eread(){
/* call eread recursively to get subtrees, if any */
register NODE *p;
register i, c;
register char *pc;
register j;
i = rdin( 10 );
p = talloc();
p->op = i;
i = optype(i);
if( i == LTYPE ) p->lval = rdin( 10 );
if( i != BITYPE ) p->rval = rdin( 10 );
p->type = rdin(8 );
p->rall = NOPREF; /* register allocation information */
if( p->op == STASG || p->op == STARG || p->op == STCALL || p->op == UNARY STCALL ){
p->stsize = (rdin( 10 ) + (SZCHAR-1) )/SZCHAR;
p->stalign = rdin(10) / SZCHAR;
if( getchar() != '\n' ) cerror( "illegal \n" );
}
else { /* usual case */
if( p->op == REG ) rbusy( p->rval, p->type ); /* non usually, but sometimes justified */
for( pc=p->name,j=0; ( c = getchar() ) != '\n'; ++j ){
if( j < NCHNAM ) *pc++ = c;
}
if( j < NCHNAM ) *pc = '\0';
}
/* now, recursively read descendents, if any */
if( i != LTYPE ) p->left = eread();
if( i == BITYPE ) p->right = eread();
return( p );
}
CONSZ
rdin( base ){
register sign, c;
CONSZ val;
sign = 1;
val = 0;
while( (c=getchar()) > 0 ) {
if( c == '-' ){
if( val != 0 ) cerror( "illegal -");
sign = -sign;
continue;
}
if( c == '\t' ) break;
if( c>='0' && c<='9' ) {
val *= base;
if( sign > 0 )
val += c-'0';
else
val -= c-'0';
continue;
}
cerror( "illegal character `%c' on intermediate file", c );
break;
}
if( c <= 0 ) {
cerror( "unexpected EOF");
}
return( val );
}
# endif
#ifndef FIELDOPS
/* do this if there is no special hardware support for fields */
ffld( p, down, down1, down2 ) NODE *p; int *down1, *down2; {
/* look for fields that are not in an lvalue context, and rewrite them... */
register NODE *shp;
register s, o, v, ty;
*down1 = asgop( p->op );
*down2 = 0;
if( !down && p->op == FLD ){ /* rewrite the node */
if( !rewfld(p) ) return;
ty = (szty(p->type) == 2)? LONG: INT;
v = p->rval;
s = UPKFSZ(v);
# ifdef RTOLBYTES
o = UPKFOFF(v); /* amount to shift */
# else
o = szty(p->type)*SZINT - s - UPKFOFF(v); /* amount to shift */
#endif
/* make & mask part */
p->left->type = ty;
p->op = AND;
p->right = talloc();
p->right->op = ICON;
p->right->rall = NOPREF;
p->right->type = ty;
p->right->lval = 1;
p->right->rval = 0;
p->right->name[0] = '\0';
p->right->lval <<= s;
p->right->lval--;
/* now, if a shift is needed, do it */
if( o != 0 ){
shp = talloc();
shp->op = RS;
shp->rall = NOPREF;
shp->type = ty;
shp->left = p->left;
shp->right = talloc();
shp->right->op = ICON;
shp->right->rall = NOPREF;
shp->right->type = ty;
shp->right->rval = 0;
shp->right->lval = o; /* amount to shift */
shp->right->name[0] = '\0';
p->left = shp;
/* whew! */
}
}
}
#endif
oreg2( p ) register NODE *p; {
/* look for situations where we can turn * into OREG */
NODE *q;
register i;
register r;
register char *cp;
register NODE *ql, *qr;
CONSZ temp;
if( p->op == UNARY MUL ){
q = p->left;
if( q->op == REG ){
temp = q->lval;
r = q->rval;
cp = q->name;
goto ormake;
}
if( q->op != PLUS && q->op != MINUS ) return;
ql = q->left;
qr = q->right;
#ifdef R2REGS
/* look for doubly indexed expressions */
if( q->op==PLUS && qr->op==REG && ql->op==REG &&
(szty(ql->type)==1||szty(qr->type)==1) ) {
temp = 0;
cp = ql->name;
if( *cp ){
if( *qr->name ) return;
}
else {
cp = qr->name;
}
if( szty(qr->type)>1) r = R2PACK(qr->rval,ql->rval);
else r = R2PACK(ql->rval,qr->rval);
goto ormake;
}
if( (q->op==PLUS||q->op==MINUS) && qr->op==ICON && ql->op==PLUS &&
ql->left->op==REG &&
ql->right->op==REG ){
temp = qr->lval;
cp = qr->name;
if( q->op == MINUS ){
if( *cp ) return;
temp = -temp;
}
if( *cp ){
if( *ql->name ) return;
}
else {
cp = ql->name;
}
r = R2PACK(ql->left->rval,ql->right->rval);
goto ormake;
}
#endif
if( (q->op==PLUS || q->op==MINUS) && qr->op == ICON &&
ql->op==REG && szty(qr->type)==1) {
temp = qr->lval;
if( q->op == MINUS ) temp = -temp;
r = ql->rval;
temp += ql->lval;
cp = qr->name;
if( *cp && ( q->op == MINUS || *ql->name ) ) return;
if( !*cp ) cp = ql->name;
ormake:
if( notoff( p->type, r, temp, cp ) ) return;
p->op = OREG;
p->rval = r;
p->lval = temp;
for( i=0; i<NCHNAM; ++i )
p->name[i] = *cp++;
tfree(q);
return;
}
}
}
canon(p) NODE *p; {
/* put p in canonical form */
int oreg2(), sucomp();
#ifndef FIELDOPS
int ffld();
fwalk( p, ffld, 0 ); /* look for field operators */
# endif
walkf( p, oreg2 ); /* look for and create OREG nodes */
#ifdef MYCANON
MYCANON(p); /* your own canonicalization routine(s) */
#endif
walkf( p, sucomp ); /* do the Sethi-Ullman computation */
}