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go / go / dev.power64 / . / src / cmd / 9c / peep.c
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// cmd/9c/peep.c from Vita Nuova.
//
// Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved.
// Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
// Portions Copyright © 1997-1999 Vita Nuova Limited
// Portions Copyright © 2000-2008 Vita Nuova Holdings Limited (www.vitanuova.com)
// Portions Copyright © 2004,2006 Bruce Ellis
// Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
// Revisions Copyright © 2000-2008 Lucent Technologies Inc. and others
// Portions Copyright © 2009 The Go Authors. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
#include "gc.h"
/*
static Reg*
rnops(Reg *r)
{
Prog *p;
Reg *r1;
if(r != R)
for(;;){
p = r->prog;
if(p->as != ANOP || p->from.type != D_NONE || p->to.type != D_NONE)
break;
r1 = uniqs(r);
if(r1 == R)
break;
r = r1;
}
return r;
}
*/
void
peep(void)
{
Reg *r, *r1, *r2;
Prog *p, *p1;
int t;
/*
* complete R structure
*/
t = 0;
for(r=firstr; r!=R; r=r1) {
r1 = r->link;
if(r1 == R)
break;
p = r->prog->link;
while(p != r1->prog)
switch(p->as) {
default:
r2 = rega();
r->link = r2;
r2->link = r1;
r2->prog = p;
r2->p1 = r;
r->s1 = r2;
r2->s1 = r1;
r1->p1 = r2;
r = r2;
t++;
case ADATA:
case AGLOBL:
case ANAME:
case ASIGNAME:
p = p->link;
}
}
loop1:
t = 0;
for(r=firstr; r!=R; r=r->link) {
p = r->prog;
if(p->as == AMOVW || p->as == AMOVD || p->as == AFMOVS || p->as == AFMOVD)
if(regtyp(&p->to)) {
if(regtyp(&p->from))
if(p->from.type == p->to.type) {
if(copyprop(r)) {
excise(r);
t++;
} else
if(subprop(r) && copyprop(r)) {
excise(r);
t++;
}
}
if(regzer(&p->from))
if(p->to.type == D_REG) {
p->from.type = D_REG;
p->from.reg = REGZERO;
if(copyprop(r)) {
excise(r);
t++;
} else
if(subprop(r) && copyprop(r)) {
excise(r);
t++;
}
}
}
}
if(t)
goto loop1;
/*
* look for MOVB x,R; MOVB R,R
*/
for(r=firstr; r!=R; r=r->link) {
p = r->prog;
switch(p->as) {
default:
continue;
case AMOVH:
case AMOVHZ:
case AMOVB:
case AMOVBZ:
case AMOVW:
case AMOVWZ:
if(p->to.type != D_REG)
continue;
break;
}
r1 = r->link;
if(r1 == R)
continue;
p1 = r1->prog;
if(p1->as != p->as)
continue;
if(p1->from.type != D_REG || p1->from.reg != p->to.reg)
continue;
if(p1->to.type != D_REG || p1->to.reg != p->to.reg)
continue;
excise(r1);
}
if(debug['D'] > 1)
return; /* allow following code improvement to be suppressed */
/*
* look for OP x,y,R; CMP R, $0 -> OPCC x,y,R
* when OP can set condition codes correctly
*/
for(r=firstr; r!=R; r=r->link) {
p = r->prog;
switch(p->as) {
case ACMP:
case ACMPW: /* always safe? */
if(!regzer(&p->to))
continue;
r1 = r->s1;
if(r1 == R)
continue;
switch(r1->prog->as) {
default:
continue;
case ABCL:
case ABC:
/* the conditions can be complex and these are currently little used */
continue;
case ABEQ:
case ABGE:
case ABGT:
case ABLE:
case ABLT:
case ABNE:
case ABVC:
case ABVS:
break;
}
r1 = r;
do
r1 = uniqp(r1);
while (r1 != R && r1->prog->as == ANOP);
if(r1 == R)
continue;
p1 = r1->prog;
if(p1->to.type != D_REG || p1->to.reg != p->from.reg)
continue;
switch(p1->as) {
case ASUB:
case AADD:
case AXOR:
case AOR:
/* irregular instructions */
if(p1->from.type == D_CONST)
continue;
break;
}
switch(p1->as) {
default:
continue;
case AMOVW:
case AMOVD:
if(p1->from.type != D_REG)
continue;
continue;
case AANDCC:
case AANDNCC:
case AORCC:
case AORNCC:
case AXORCC:
case ASUBCC:
case ASUBECC:
case ASUBMECC:
case ASUBZECC:
case AADDCC:
case AADDCCC:
case AADDECC:
case AADDMECC:
case AADDZECC:
case ARLWMICC:
case ARLWNMCC:
t = p1->as;
break;
/* don't deal with floating point instructions for now */
/*
case AFABS: t = AFABSCC; break;
case AFADD: t = AFADDCC; break;
case AFADDS: t = AFADDSCC; break;
case AFCTIW: t = AFCTIWCC; break;
case AFCTIWZ: t = AFCTIWZCC; break;
case AFDIV: t = AFDIVCC; break;
case AFDIVS: t = AFDIVSCC; break;
case AFMADD: t = AFMADDCC; break;
case AFMADDS: t = AFMADDSCC; break;
case AFMOVD: t = AFMOVDCC; break;
case AFMSUB: t = AFMSUBCC; break;
case AFMSUBS: t = AFMSUBSCC; break;
case AFMUL: t = AFMULCC; break;
case AFMULS: t = AFMULSCC; break;
case AFNABS: t = AFNABSCC; break;
case AFNEG: t = AFNEGCC; break;
case AFNMADD: t = AFNMADDCC; break;
case AFNMADDS: t = AFNMADDSCC; break;
case AFNMSUB: t = AFNMSUBCC; break;
case AFNMSUBS: t = AFNMSUBSCC; break;
case AFRSP: t = AFRSPCC; break;
case AFSUB: t = AFSUBCC; break;
case AFSUBS: t = AFSUBSCC; break;
case ACNTLZW: t = ACNTLZWCC; break;
case AMTFSB0: t = AMTFSB0CC; break;
case AMTFSB1: t = AMTFSB1CC; break;
*/
case AADD: t = AADDCC; break;
case AADDV: t = AADDVCC; break;
case AADDC: t = AADDCCC; break;
case AADDCV: t = AADDCVCC; break;
case AADDME: t = AADDMECC; break;
case AADDMEV: t = AADDMEVCC; break;
case AADDE: t = AADDECC; break;
case AADDEV: t = AADDEVCC; break;
case AADDZE: t = AADDZECC; break;
case AADDZEV: t = AADDZEVCC; break;
case AAND: t = AANDCC; break;
case AANDN: t = AANDNCC; break;
case ADIVW: t = ADIVWCC; break;
case ADIVWV: t = ADIVWVCC; break;
case ADIVWU: t = ADIVWUCC; break;
case ADIVWUV: t = ADIVWUVCC; break;
case ADIVD: t = ADIVDCC; break;
case ADIVDV: t = ADIVDVCC; break;
case ADIVDU: t = ADIVDUCC; break;
case ADIVDUV: t = ADIVDUVCC; break;
case AEQV: t = AEQVCC; break;
case AEXTSB: t = AEXTSBCC; break;
case AEXTSH: t = AEXTSHCC; break;
case AEXTSW: t = AEXTSWCC; break;
case AMULHW: t = AMULHWCC; break;
case AMULHWU: t = AMULHWUCC; break;
case AMULLW: t = AMULLWCC; break;
case AMULLWV: t = AMULLWVCC; break;
case AMULHD: t = AMULHDCC; break;
case AMULHDU: t = AMULHDUCC; break;
case AMULLD: t = AMULLDCC; break;
case AMULLDV: t = AMULLDVCC; break;
case ANAND: t = ANANDCC; break;
case ANEG: t = ANEGCC; break;
case ANEGV: t = ANEGVCC; break;
case ANOR: t = ANORCC; break;
case AOR: t = AORCC; break;
case AORN: t = AORNCC; break;
case AREM: t = AREMCC; break;
case AREMV: t = AREMVCC; break;
case AREMU: t = AREMUCC; break;
case AREMUV: t = AREMUVCC; break;
case AREMD: t = AREMDCC; break;
case AREMDV: t = AREMDVCC; break;
case AREMDU: t = AREMDUCC; break;
case AREMDUV: t = AREMDUVCC; break;
case ARLWMI: t = ARLWMICC; break;
case ARLWNM: t = ARLWNMCC; break;
case ASLW: t = ASLWCC; break;
case ASRAW: t = ASRAWCC; break;
case ASRW: t = ASRWCC; break;
case ASLD: t = ASLDCC; break;
case ASRAD: t = ASRADCC; break;
case ASRD: t = ASRDCC; break;
case ASUB: t = ASUBCC; break;
case ASUBV: t = ASUBVCC; break;
case ASUBC: t = ASUBCCC; break;
case ASUBCV: t = ASUBCVCC; break;
case ASUBME: t = ASUBMECC; break;
case ASUBMEV: t = ASUBMEVCC; break;
case ASUBE: t = ASUBECC; break;
case ASUBEV: t = ASUBEVCC; break;
case ASUBZE: t = ASUBZECC; break;
case ASUBZEV: t = ASUBZEVCC; break;
case AXOR: t = AXORCC; break;
break;
}
if(debug['D'])
print("cmp %P; %P -> ", p1, p);
p1->as = t;
if(debug['D'])
print("%P\n", p1);
excise(r);
continue;
}
}
}
void
excise(Reg *r)
{
Prog *p;
p = r->prog;
p->as = ANOP;
p->from = zprog.from;
p->from3 = zprog.from3;
p->to = zprog.to;
p->reg = zprog.reg; /**/
}
Reg*
uniqp(Reg *r)
{
Reg *r1;
r1 = r->p1;
if(r1 == R) {
r1 = r->p2;
if(r1 == R || r1->p2link != R)
return R;
} else
if(r->p2 != R)
return R;
return r1;
}
Reg*
uniqs(Reg *r)
{
Reg *r1;
r1 = r->s1;
if(r1 == R) {
r1 = r->s2;
if(r1 == R)
return R;
} else
if(r->s2 != R)
return R;
return r1;
}
/*
* if the system forces R0 to be zero,
* convert references to $0 to references to R0.
*/
int
regzer(Addr *a)
{
if(R0ISZERO) {
if(a->type == D_CONST)
if(a->sym == nil)
if(a->offset == 0)
return 1;
if(a->type == D_REG)
if(a->reg == REGZERO)
return 1;
}
return 0;
}
int
regtyp(Addr *a)
{
if(a->type == D_REG) {
if(!R0ISZERO || a->reg != REGZERO)
return 1;
return 0;
}
if(a->type == D_FREG)
return 1;
return 0;
}
/*
* the idea is to substitute
* one register for another
* from one MOV to another
* MOV a, R0
* ADD b, R0 / no use of R1
* MOV R0, R1
* would be converted to
* MOV a, R1
* ADD b, R1
* MOV R1, R0
* hopefully, then the former or latter MOV
* will be eliminated by copy propagation.
*/
int
subprop(Reg *r0)
{
Prog *p;
Addr *v1, *v2;
Reg *r;
int t;
p = r0->prog;
v1 = &p->from;
if(!regtyp(v1))
return 0;
v2 = &p->to;
if(!regtyp(v2))
return 0;
for(r=uniqp(r0); r!=R; r=uniqp(r)) {
if(uniqs(r) == R)
break;
p = r->prog;
switch(p->as) {
case ABL:
return 0;
case AADD:
case AADDC:
case AADDCC:
case AADDE:
case AADDECC:
case ASUB:
case ASUBCC:
case ASUBC:
case ASUBCCC:
case ASUBE:
case ASUBECC:
case ASLW:
case ASRW:
case ASRWCC:
case ASRAW:
case ASRAWCC:
case ASLD:
case ASRD:
case ASRAD:
case AOR:
case AORCC:
case AORN:
case AORNCC:
case AAND:
case AANDCC:
case AANDN:
case AANDNCC:
case ANAND:
case ANANDCC:
case ANOR:
case ANORCC:
case AXOR:
case AXORCC:
case AMULHW:
case AMULHWU:
case AMULLW:
case AMULLD:
case ADIVW:
case ADIVWU:
case ADIVD:
case ADIVDU:
case AREM:
case AREMU:
case AREMD:
case AREMDU:
case ARLWNM:
case ARLWNMCC:
case AFADD:
case AFADDS:
case AFSUB:
case AFSUBS:
case AFMUL:
case AFMULS:
case AFDIV:
case AFDIVS:
if(p->to.type == v1->type)
if(p->to.reg == v1->reg) {
if(p->reg == NREG)
p->reg = p->to.reg;
goto gotit;
}
break;
case AADDME:
case AADDMECC:
case AADDZE:
case AADDZECC:
case ASUBME:
case ASUBMECC:
case ASUBZE:
case ASUBZECC:
case ANEG:
case ANEGCC:
case AFNEG:
case AFNEGCC:
case AFMOVS:
case AFMOVD:
case AMOVW:
case AMOVD:
if(p->to.type == v1->type)
if(p->to.reg == v1->reg)
goto gotit;
break;
}
if(copyau(&p->from, v2) ||
copyau1(p, v2) ||
copyau(&p->to, v2))
break;
if(copysub(&p->from, v1, v2, 0) ||
copysub1(p, v1, v2, 0) ||
copysub(&p->to, v1, v2, 0))
break;
}
return 0;
gotit:
copysub(&p->to, v1, v2, 1);
if(debug['P']) {
print("gotit: %D->%D\n%P", v1, v2, r->prog);
if(p->from.type == v2->type)
print(" excise");
print("\n");
}
for(r=uniqs(r); r!=r0; r=uniqs(r)) {
p = r->prog;
copysub(&p->from, v1, v2, 1);
copysub1(p, v1, v2, 1);
copysub(&p->to, v1, v2, 1);
if(debug['P'])
print("%P\n", r->prog);
}
t = v1->reg;
v1->reg = v2->reg;
v2->reg = t;
if(debug['P'])
print("%P last\n", r->prog);
return 1;
}
/*
* The idea is to remove redundant copies.
* v1->v2 F=0
* (use v2 s/v2/v1/)*
* set v1 F=1
* use v2 return fail
* -----------------
* v1->v2 F=0
* (use v2 s/v2/v1/)*
* set v1 F=1
* set v2 return success
*/
int
copyprop(Reg *r0)
{
Prog *p;
Addr *v1, *v2;
Reg *r;
p = r0->prog;
v1 = &p->from;
v2 = &p->to;
if(copyas(v1, v2))
return 1;
for(r=firstr; r!=R; r=r->link)
r->active = 0;
return copy1(v1, v2, r0->s1, 0);
}
int
copy1(Addr *v1, Addr *v2, Reg *r, int f)
{
int t;
Prog *p;
if(r->active) {
if(debug['P'])
print("act set; return 1\n");
return 1;
}
r->active = 1;
if(debug['P'])
print("copy %D->%D f=%d\n", v1, v2, f);
for(; r != R; r = r->s1) {
p = r->prog;
if(debug['P'])
print("%P", p);
if(!f && uniqp(r) == R) {
f = 1;
if(debug['P'])
print("; merge; f=%d", f);
}
t = copyu(p, v2, nil);
switch(t) {
case 2: /* rar, cant split */
if(debug['P'])
print("; %Drar; return 0\n", v2);
return 0;
case 3: /* set */
if(debug['P'])
print("; %Dset; return 1\n", v2);
return 1;
case 1: /* used, substitute */
case 4: /* use and set */
if(f) {
if(!debug['P'])
return 0;
if(t == 4)
print("; %Dused+set and f=%d; return 0\n", v2, f);
else
print("; %Dused and f=%d; return 0\n", v2, f);
return 0;
}
if(copyu(p, v2, v1)) {
if(debug['P'])
print("; sub fail; return 0\n");
return 0;
}
if(debug['P'])
print("; sub%D/%D", v2, v1);
if(t == 4) {
if(debug['P'])
print("; %Dused+set; return 1\n", v2);
return 1;
}
break;
}
if(!f) {
t = copyu(p, v1, nil);
if(!f && (t == 2 || t == 3 || t == 4)) {
f = 1;
if(debug['P'])
print("; %Dset and !f; f=%d", v1, f);
}
}
if(debug['P'])
print("\n");
if(r->s2)
if(!copy1(v1, v2, r->s2, f))
return 0;
}
return 1;
}
/*
* return
* 1 if v only used (and substitute),
* 2 if read-alter-rewrite
* 3 if set
* 4 if set and used
* 0 otherwise (not touched)
*/
int
copyu(Prog *p, Addr *v, Addr *s)
{
switch(p->as) {
default:
if(debug['P'])
print(" (\?\?\?)");
return 2;
case ANOP: /* read, write */
case AMOVH:
case AMOVHZ:
case AMOVB:
case AMOVBZ:
case AMOVW:
case AMOVWZ:
case AMOVD:
case ANEG:
case ANEGCC:
case AADDME:
case AADDMECC:
case AADDZE:
case AADDZECC:
case ASUBME:
case ASUBMECC:
case ASUBZE:
case ASUBZECC:
case AFCTIW:
case AFCTIWZ:
case AFMOVS:
case AFMOVD:
case AFRSP:
case AFNEG:
case AFNEGCC:
if(s != nil) {
if(copysub(&p->from, v, s, 1))
return 1;
if(!copyas(&p->to, v))
if(copysub(&p->to, v, s, 1))
return 1;
return 0;
}
if(copyas(&p->to, v)) {
if(copyau(&p->from, v))
return 4;
return 3;
}
if(copyau(&p->from, v))
return 1;
if(copyau(&p->to, v))
return 1;
return 0;
case ARLWMI: /* read read rar */
case ARLWMICC:
if(copyas(&p->to, v))
return 2;
/* fall through */
case AADD: /* read read write */
case AADDC:
case AADDE:
case ASUB:
case ASLW:
case ASRW:
case ASRAW:
case ASLD:
case ASRD:
case ASRAD:
case AOR:
case AORCC:
case AORN:
case AORNCC:
case AAND:
case AANDCC:
case AANDN:
case AANDNCC:
case ANAND:
case ANANDCC:
case ANOR:
case ANORCC:
case AXOR:
case AMULHW:
case AMULHWU:
case AMULLW:
case AMULLD:
case ADIVW:
case ADIVD:
case ADIVWU:
case ADIVDU:
case AREM:
case AREMU:
case AREMD:
case AREMDU:
case ARLWNM:
case ARLWNMCC:
case AFADDS:
case AFADD:
case AFSUBS:
case AFSUB:
case AFMULS:
case AFMUL:
case AFDIVS:
case AFDIV:
if(s != nil) {
if(copysub(&p->from, v, s, 1))
return 1;
if(copysub1(p, v, s, 1))
return 1;
if(!copyas(&p->to, v))
if(copysub(&p->to, v, s, 1))
return 1;
return 0;
}
if(copyas(&p->to, v)) {
if(p->reg == NREG)
p->reg = p->to.reg;
if(copyau(&p->from, v))
return 4;
if(copyau1(p, v))
return 4;
return 3;
}
if(copyau(&p->from, v))
return 1;
if(copyau1(p, v))
return 1;
if(copyau(&p->to, v))
return 1;
return 0;
case ABEQ:
case ABGT:
case ABGE:
case ABLT:
case ABLE:
case ABNE:
case ABVC:
case ABVS:
break;
case ACMP: /* read read */
case ACMPU:
case ACMPW:
case ACMPWU:
case AFCMPO:
case AFCMPU:
if(s != nil) {
if(copysub(&p->from, v, s, 1))
return 1;
return copysub(&p->to, v, s, 1);
}
if(copyau(&p->from, v))
return 1;
if(copyau(&p->to, v))
return 1;
break;
case ABR: /* funny */
if(s != nil) {
if(copysub(&p->to, v, s, 1))
return 1;
return 0;
}
if(copyau(&p->to, v))
return 1;
return 0;
case ARETURN: /* funny */
if(v->type == D_REG)
if(v->reg == REGRET)
return 2;
if(v->type == D_FREG)
if(v->reg == FREGRET)
return 2;
case ABL: /* funny */
if(v->type == D_REG) {
if(v->reg <= REGEXT && v->reg > exregoffset)
return 2;
if(v->reg == REGARG)
return 2;
}
if(v->type == D_FREG) {
if(v->reg <= FREGEXT && v->reg > exfregoffset)
return 2;
}
if(s != nil) {
if(copysub(&p->to, v, s, 1))
return 1;
return 0;
}
if(copyau(&p->to, v))
return 4;
return 3;
case ATEXT: /* funny */
if(v->type == D_REG)
if(v->reg == REGARG)
return 3;
return 0;
}
return 0;
}
int
a2type(Prog *p)
{
switch(p->as) {
case AADD:
case AADDC:
case AADDCC:
case AADDCCC:
case AADDE:
case AADDECC:
case AADDME:
case AADDMECC:
case AADDZE:
case AADDZECC:
case ASUB:
case ASUBC:
case ASUBCC:
case ASUBCCC:
case ASUBE:
case ASUBECC:
case ASUBME:
case ASUBMECC:
case ASUBZE:
case ASUBZECC:
case ASLW:
case ASLWCC:
case ASRW:
case ASRWCC:
case ASRAW:
case ASRAWCC:
case ASLD:
case ASLDCC:
case ASRD:
case ASRDCC:
case ASRAD:
case ASRADCC:
case AOR:
case AORCC:
case AORN:
case AORNCC:
case AAND:
case AANDCC:
case AANDN:
case AANDNCC:
case AXOR:
case AXORCC:
case ANEG:
case ANEGCC:
case AMULHW:
case AMULHWU:
case AMULLW:
case AMULLWCC:
case ADIVW:
case ADIVWCC:
case ADIVWU:
case ADIVWUCC:
case AREM:
case AREMCC:
case AREMU:
case AREMUCC:
case AMULLD:
case AMULLDCC:
case ADIVD:
case ADIVDCC:
case ADIVDU:
case ADIVDUCC:
case AREMD:
case AREMDCC:
case AREMDU:
case AREMDUCC:
case ANAND:
case ANANDCC:
case ANOR:
case ANORCC:
case ARLWMI:
case ARLWMICC:
case ARLWNM:
case ARLWNMCC:
return D_REG;
case AFADDS:
case AFADDSCC:
case AFADD:
case AFADDCC:
case AFSUBS:
case AFSUBSCC:
case AFSUB:
case AFSUBCC:
case AFMULS:
case AFMULSCC:
case AFMUL:
case AFMULCC:
case AFDIVS:
case AFDIVSCC:
case AFDIV:
case AFDIVCC:
case AFNEG:
case AFNEGCC:
return D_FREG;
}
return D_NONE;
}
/*
* direct reference,
* could be set/use depending on
* semantics
*/
int
copyas(Addr *a, Addr *v)
{
if(regtyp(v))
if(a->type == v->type)
if(a->reg == v->reg)
return 1;
return 0;
}
/*
* either direct or indirect
*/
int
copyau(Addr *a, Addr *v)
{
if(copyas(a, v))
return 1;
if(v->type == D_REG)
if(a->type == D_OREG)
if(v->reg == a->reg)
return 1;
return 0;
}
int
copyau1(Prog *p, Addr *v)
{
if(regtyp(v))
if(p->from.type == v->type || p->to.type == v->type)
if(p->reg == v->reg) {
if(a2type(p) != v->type)
print("botch a2type %P\n", p);
return 1;
}
return 0;
}
/*
* substitute s for v in a
* return failure to substitute
*/
int
copysub(Addr *a, Addr *v, Addr *s, int f)
{
if(f)
if(copyau(a, v))
a->reg = s->reg;
return 0;
}
int
copysub1(Prog *p1, Addr *v, Addr *s, int f)
{
if(f)
if(copyau1(p1, v))
p1->reg = s->reg;
return 0;
}