ref: d1cebf608b05e45b148108ac6c16ae94f6862097
dir: /sys/src/cmd/2c/peep.c/
#include "gc.h"
void
peep(void)
{
Reg *r, *r1, *r2;
Prog *p, *p1;
int t, s;
/*
* 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:
/*
* propigate move's by renaming
*/
t = 0;
for(r=firstr; r!=R; r=r->link) {
p = r->prog;
if(p->as == AMOVL || p->as == AFMOVEF || p->as == AFMOVED)
if(regtyp(p->from.type))
if(anyvar(&p->to)) {
if(copyprop(r)) {
excise(r);
t++;
} else
if(subprop(r) && copyprop(r)) {
excise(r);
t++;
}
}
}
if(t)
goto loop1;
for(r=firstr; r!=R; r=r->link) {
p = r->prog;
/*
* convert (A) ... A++ into (A)++
* and A-- ... (A) into --(A)
*/
t = aregind(&p->from);
if(t == D_NONE)
goto out1;
s = asize(p->as);
if(s == 0)
goto out1;
r1 = findop(r, t, AADDL, s);
if(r1 != R) {
if(usedin(t, &p->to))
goto out1;
p->from.type += I_INDINC - I_INDIR;
excise(r1);
goto out1;
}
r1 = findop(r, t, ASUBL, s);
if(r1 != R) {
p->from.type += I_INDDEC - I_INDIR;
excise(r1);
}
out1:
t = aregind(&p->to);
if(t == D_NONE)
goto out2;
s = asize(p->as);
if(s == 0)
goto out2;
r1 = findop(r, t, AADDL, s);
if(r1 != R) {
p->to.type += I_INDINC - I_INDIR;
excise(r1);
goto out2;
}
r1 = findop(r, t, ASUBL, s);
if(r1 != R) {
if(usedin(t, &p->from))
goto out2;
p->to.type += I_INDDEC - I_INDIR;
excise(r1);
}
out2:
/*
* get rid of unneeded save/restore CCR
*/
if(p->from.type == D_CCR) {
r1 = findccr(r);
if(r1 != R) {
excise(r);
excise(r1);
}
}
switch(p->as) {
case ATSTB:
case ATSTW:
case ATSTL:
if(findtst(r, r->prog, 0))
excise(r);
}
/*
* turn TSTB (A); BLT; ORB $128,(A) into TAS (A); BLT; NOP
*/
if(p->as == ATSTB && (r1 = r->s1)) {
if((r1->prog->as == ABLT && (r2 = r1->s1)) ||
(r1->prog->as == ABGE && (r2 = r1->s2))) {
p1 = r2->prog;
if(p1->as == AORB)
if(p1->from.type == D_CONST)
if(p1->from.offset == 128)
if(r1 == uniqp(r2))
if(tasas(&p->to, &p1->to)) {
p->as = ATAS;
excise(r2);
}
}
}
}
}
void
excise(Reg *r)
{
p = r->prog;
p->as = ANOP;
p->from = zprog.from;
p->to = zprog.to;
}
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;
}
/*
* chase backward all cc setting.
* returns 1 if all set same.
*/
int
findtst(Reg *r0, Prog *rp, int n)
{
Reg *r;
int c;
loop:
n++;
if(n >= 10)
return 0;
for(r=r0->p2; r!=R; r=r->p2link) {
c = setcc(r->prog, rp);
if(c > 0)
continue;
if(c == 0)
return 0;
if(findtst(r, rp, n) == 0)
return 0;
}
r = r0->p1;
if(r == R)
return 1;
c = setcc(r->prog, rp);
if(c > 0)
return 1;
if(c == 0)
return 0;
r0 = r;
goto loop;
}
/*
* tests cc
* returns -1 if no change
* returns 1 if set the same
* returns 0 if set different
*/
int
setcc(Prog *p, Prog *rp)
{
int s;
s = asize(rp->as);
switch(p->as) {
default:
if(debug['P'])
print("unknown setcc %A\n", p->as);
break;
case ACMPB:
case ACMPW:
case ACMPL:
case ABSR:
return 0;
case ABRA:
case ABGE:
case ABNE:
case ABLE:
case ABEQ:
case ABHI:
case ABLS:
case ABMI:
case ABPL:
case ABGT:
case ABLT:
case ABCC:
case ABCS:
case APEA:
case ALEA:
case ANOP:
case AFADDD:
case AFMULD:
case AFDIVD:
case AFSUBD:
case AFADDF:
case AFMULF:
case AFDIVF:
case AFSUBF:
case AADJSP:
return -1;
case AADDW:
case AADDL:
case ASUBW:
case ASUBL:
case ACLRL:
case ACLRW:
if(p->to.type >= D_A0 && p->to.type < D_A0+8)
goto areg;
case AADDB:
case ASUBB:
case AANDB:
case AANDW:
case AANDL:
case AORB:
case AORW:
case AORL:
case AEORB:
case AEORW:
case AEORL:
case ALSLB:
case ALSLW:
case ALSLL:
case ALSRB:
case ALSRW:
case ALSRL:
case AASLB:
case AASLW:
case AASLL:
case AASRB:
case AASRW:
case AASRL:
case ATSTB:
case ATSTW:
case ATSTL:
case ANEGB:
case ANEGW:
case ANEGL:
case ACLRB:
if(asize(p->as) != s)
break;
if(compat(&rp->to, &p->to))
return 1;
break;
case AMOVW:
case AMOVL:
if(p->to.type >= D_A0 && p->to.type < D_A0+8)
goto areg;
case AMOVB:
if(asize(p->as) != s)
break;
if(compat(&rp->to, &p->to))
return 1;
if(compat(&rp->to, &p->from))
return 1;
}
return 0;
areg:
if((rp->to.type&D_MASK) == p->to.type)
return 0;
return -1;
}
int
compat(Adr *a, Adr *b)
{
int o;
if(a->index != D_NONE)
return 0;
if(b->index != D_NONE)
return 0;
o = a->type;
if((o >= D_R0 && o < D_R0+NREG) ||
(o >= D_A0 && o < D_A0+NREG))
return o == b->type;
o &= D_MASK;
if(o >= D_A0 && o < D_A0+NREG) {
if(o != (b->type&D_MASK))
return 0;
if(a->offset != b->offset)
return 0;
o = a->type & I_MASK;
if(o == I_INDIR) {
o = b->type & I_MASK;
if(o == I_INDIR || o == I_INDDEC)
return 1;
return 0;
}
if(o == I_INDINC) {
o = b->type & I_MASK;
if(o == I_INDIR) {
b->type += I_INDINC-I_INDIR;
return 1;
}
if(o == I_INDDEC) {
b->type += I_INDIR-I_INDDEC;
return 1;
}
return 0;
}
}
return 0;
}
int
aregind(Adr *a)
{
int t;
t = a->type;
if(t >= (D_A0|I_INDIR) && t < ((D_A0+NREG)|I_INDIR))
while(a->offset == 0 && a->index == D_NONE)
return t & D_MASK;
return D_NONE;
}
int
asize(int a)
{
switch(a) {
case AFTSTD:
case AFMOVED:
case AFADDD:
case AFSUBD:
case AFMULD:
case AFDIVD:
case AFCMPD:
case AFNEGD:
return 8;
case AFTSTF:
case AFMOVEF:
case AFADDF:
case AFSUBF:
case AFMULF:
case AFDIVF:
case AFCMPF:
case AFNEGF:
case ACLRL:
case ATSTL:
case AMOVL:
case AADDL:
case ASUBL:
case ACMPL:
case AANDL:
case AORL:
case AEORL:
case ALSLL:
case ALSRL:
case AASLL:
case AASRL:
case ANEGL:
return 4;
case ACLRW:
case ATSTW:
case AMOVW:
case AADDW:
case ASUBW:
case ACMPW:
case AANDW:
case AORW:
case AEORW:
case ALSLW:
case ALSRW:
case AASLW:
case AASRW:
case ANEGW:
return 2;
case ACLRB:
case ATSTB:
case AMOVB:
case AADDB:
case ASUBB:
case ACMPB:
case AANDB:
case AORB:
case AEORB:
case ALSLB:
case ALSRB:
case AASLB:
case AASRB:
case ANEGB:
return 1;
}
if(debug['P'])
print("unknown asize %A\n", p->as);
return 0;
}
int
usedin(int t, Adr *a)
{
if((a->type&D_MASK) == t)
return 1;
if((a->index&D_MASK) == t)
return 1;
return 0;
}
Reg*
findccr(Reg *r)
{
Prog *p;
for(;;) {
r = uniqs(r);
if(r == R)
break;
p = r->prog;
if(p->to.type == D_CCR)
return r;
if(setccr(p))
break;
}
return R;
}
int
setccr(Prog *p)
{
switch(p->as) {
case ANOP:
return 0;
case AADDL:
case AMOVL:
case ACLRL:
if(p->to.type >= D_A0 && p->to.type < D_A0+8)
return 0;
}
return 1;
}
Reg*
findop(Reg *r, int t, int o, int s)
{
Prog *p;
Reg *r1;
for(;;) {
if(o == AADDL) {
r1 = uniqs(r);
if(r1 == R)
break;
if(uniqp(r1) != r)
break;
} else {
r1 = uniqp(r);
if(r1 == R)
break;
if(uniqs(r1) != r)
break;
}
r = r1;
p = r->prog;
if(usedin(t, &p->from))
break;
if(usedin(t, &p->to)) {
if(p->as == o)
if(p->to.type == t)
if(p->to.index == D_NONE)
if(p->from.type == D_CONST)
if(p->from.offset == s)
return r;
break;
}
}
return R;
}
int
regtyp(int t)
{
if(t >= D_R0 && t < D_R0+8)
return 1;
if(t >= D_A0 && t < D_A0+8)
return 1;
if(t >= D_F0 && t < D_F0+8)
return 1;
return 0;
}
int
anyvar(Adr *a)
{
if(regtyp(a->type))
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 MOVL
* will be eliminated by copy propagation.
*/
int
subprop(Reg *r0)
{
Prog *p;
Adr *v1, *v2;
Reg *r;
int t;
p = r0->prog;
v1 = &p->from;
if(!regtyp(v1->type))
return 0;
v2 = &p->to;
if(!regtyp(v2->type))
return 0;
for(r=uniqp(r0); r!=R; r=uniqp(r)) {
if(uniqs(r) == R)
break;
p = r->prog;
switch(p->as) {
case ADIVUW: /* these set Rn and Rn+1 */
case ADIVUL:
case ADIVSW:
case ADIVSL:
case ABSR:
return 0;
case AFMOVED:
case AFMOVEF:
case AMOVL:
if(p->to.type == v1->type)
goto gotit;
}
if(copyau(&p->from, v2) || copyau(&p->to, v2))
break;
if(copysub(&p->from, v1, v2, p, 0) || copysub(&p->to, v1, v2, p, 0))
break;
}
return 0;
gotit:
copysub(&p->to, v1, v2, p, 1);
if(debug['P']) {
print("gotit: %D->%D\n%P", v1, v2, r->prog);
if(p->from.type == v2->type)
print(" excise");
print("\n");
}
if(p->from.type == v2->type)
excise(r);
for(r=uniqs(r); r!=r0; r=uniqs(r)) {
p = r->prog;
copysub(&p->from, v1, v2, p, 1);
copysub(&p->to, v1, v2, p, 1);
if(debug['P'])
print("%P\n", r->prog);
}
t = v1->type;
v1->type = v2->type;
v2->type = 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;
Adr *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(Adr *v1, Adr *v2, Reg *r, int f)
{
int t;
if(r->active) {
if(debug['P'])
print("copyret 1\n");
return 1;
}
r->active = 1;
if(debug['P'])
print("copy %D->%D\n", v1, v2);
for(; r != R; r = r->s1) {
if(debug['P'])
print("%P", r->prog);
if(!f && uniqp(r) == R) {
f = 1;
if(debug['P'])
print("; merge; f=%d", f);
}
t = copyu(r->prog, v2, A);
switch(t) {
case 2: /* rar, cant split */
if(debug['P'])
print("; rar return 0\n");
return 0;
case 3: /* set */
if(debug['P'])
print("; set; return 1\n");
return 1;
case 1: /* used, substitute */
case 4: /* use and set */
if(f) {
if(debug['P'])
print("; used and f; return 0\n");
return 0;
}
if(copyu(r->prog, v2, v1)) {
if(debug['P'])
print("; sub fail; return 0\n");
return 0;
}
if(debug['P'])
print("; substitute");
if(t == 4) {
if(debug['P'])
print("; used and set; return 1\n");
return 1;
}
break;
}
if(!f) {
t = copyu(r->prog, v1, A);
if(!f && (t == 2 || t == 3 || t == 4)) {
if(debug['P'])
print("; f set used");
f = 1;
}
}
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, Adr *v, Adr *s)
{
int t;
switch(p->as) {
default:
if(debug['P'])
print("unknown op %A\n", p->as);
return 2;
case APEA: /* rhs addr */
if(copyas(&p->to, v))
return 2;
goto caseread;
case ALEA: /* lhs addr, rhs store */
if(copyas(&p->from, v))
return 2;
case AMOVL: /* rhs store */
case ACLRL:
case AFMOVEF:
case AFMOVED:
case AFMOVEB:
case AFMOVEW:
case AFMOVEL:
case ANOP:
if(copyas(&p->to, v)) {
if(s != A)
return copysub(&p->from, v, s, p, 1);
if(copyau(&p->from, v))
return 4;
return 3;
}
goto caseread;
case AADDL: /* rhs rar */
case AADDW:
case AADDB:
case ASUBL:
case ASUBW:
case ASUBB:
case AANDL:
case AANDW:
case AANDB:
case AORL:
case AORW:
case AORB:
case AEORL:
case AEORW:
case AEORB:
case AASRL:
case AASRW:
case AASRB:
case AASLL:
case AASLW:
case AASLB:
case ALSRL:
case ALSRW:
case ALSRB:
case ANOTL:
case ANOTW:
case ANOTB:
case ANEGL:
case ANEGW:
case ANEGB:
case AEXTBL:
case AEXTWL:
case AEXTBW:
case AMULSL:
case AMULUL:
case AMOVW: /* only sets part of register */
case AMOVB:
case ACLRW:
case ACLRB:
case AFADDD:
case AFMULD:
case AFDIVD:
case AFSUBD:
case AFNEGD:
case AFADDF:
case AFMULF:
case AFDIVF:
case AFSUBF:
case AFNEGF:
if(copyas(&p->to, v))
return 2;
goto caseread;
case ADBF: /* lhs rar */
if(copyas(&p->from, v))
return 2;
goto caseread;
case ACMPL: /* read only */
case ACMPW:
case ACMPB:
case AFCMPF:
case AFCMPD:
case ATSTL:
case ATSTW:
case ATSTB:
case AFTSTF:
case AFTSTD:
caseread:
if(s != A) {
if(copysub(&p->from, v, s, p, 1))
return 1;
return copysub(&p->to, v, s, p, 1);
}
if(copyau(&p->from, v))
return 1;
if(copyau(&p->to, v))
return 1;
break;
case ABRA: /* no reference */
case ABGE:
case ABNE:
case ABLE:
case ABEQ:
case ABHI:
case ABLS:
case ABMI:
case ABPL:
case ABGT:
case ABLT:
case ABCC:
case ABCS:
case AFBEQ:
case AFBNE:
case AFBGT:
case AFBGE:
case AFBLE:
case AFBLT:
case AADJSP:
case ACASEW:
break;
case ADIVUW: /* these set Rn and Rn+1 */
case ADIVUL:
case ADIVSW:
case ADIVSL:
t = v->type;
if(t == p->to.type || t == p->to.type+1)
return 2;
goto caseread;
case ARTS: /* funny */
t = v->type;
if(t == D_R0 || t == D_F0)
return 2;
if(t >= D_R0 && t < D_R0+NREG)
if(t-D_R0 > exregoffset)
return 2;
if(t >= D_A0 && t < D_A0+NREG)
if(t-D_A0 > exaregoffset)
return 2;
if(t >= D_F0 && t < D_F0+NREG)
if(t-D_F0 > exfregoffset)
return 2;
return 3;
case ABSR: /* funny */
t = v->type;
if(t >= D_R0 && t < D_R0+NREG)
if(t-D_R0 > exregoffset)
return 2;
if(t >= D_A0 && t < D_A0+NREG)
if(t-D_A0 > exaregoffset)
return 2;
if(t >= D_F0 && t < D_F0+NREG)
if(t-D_F0 > exfregoffset)
return 2;
return 3;
}
return 0;
}
/*
* direct reference,
* could be set/use depending on
* semantics
*/
int
copyas(Adr *a, Adr *v)
{
if(a->type != v->type)
return 0;
if(regtyp(v->type))
return 1;
if(v->type == D_AUTO || v->type == D_PARAM) {
if(v->offset == a->offset)
return 1;
return 0;
}
return 0;
}
/*
* indirect
*/
int
tasas(Adr *a, Adr *v)
{
int t;
if(a->index != D_NONE)
return 0;
if(v->index != D_NONE)
return 0;
t = a->type;
if(t < I_INDIR+D_A0 && t >= I_INDIR+D_A0+8)
return 0;
if(v->type != t)
return 0;
if(a->displace != v->displace)
return 0;
return 1;
}
/*
* either direct or indirect
*/
int
copyau(Adr *a, Adr *v)
{
int t;
if(copyas(a, v))
return 1;
t = v->type;
if(regtyp(t)) {
if((a->type & D_MASK) == t)
return 1;
if((a->index & D_MASK) == t)
return 1;
}
return 0;
}
/*
* substitute s for v in a
* return failure to substitute
*/
int
copysub(Adr *a, Adr *v, Adr *s, Prog *p, int f)
{
int t;
if(copyas(a, v)) {
t = s->type;
if(t >= D_F0 && t < D_F0+8) {
if(f)
a->type = t;
return 0;
}
if(t >= D_R0 && t < D_R0+8) {
if(f)
a->type = t;
return 0;
}
if(!(t >= D_A0 && t < D_A0+8))
return 1;
switch(p->as) {
default:
return 1;
case AMOVL:
case AMOVW:
case ACMPL:
case ACMPW:
break;
case AADDL:
case AADDW:
case ASUBL:
case ASUBW:
if(a == &p->from && !regtyp(p->to.type))
return 1;
break;
}
if(f)
a->type = t;
return 0;
}
t = v->type;
if(regtyp(t)) {
if((a->type & D_MASK) == t) {
if((s->type ^ t) & ~(NREG-1))
return 1;
if(f)
a->type = (a->type & ~D_MASK) | s->type;
return 0;
}
if((a->index & D_MASK) == t) {
if(f)
a->index = (a->index & ~D_MASK) | s->type;
return 0;
}
return 0;
}
return 0;
}