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cmd/gc: do not compute dead value maps if they will not be used

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Reduces 6g big.go memory usage from 251 MB to 242 MB.
Reduces 6g slow.go memory usage from 529 MB to 453 MB.

Mostly a memory savings; 6g slow.go is only about 5% faster.

The test programs are at
https://rsc.googlecode.com/hg/testdata/big.go (36k lines, 276kB)
https://rsc.googlecode.com/hg/testdata/slow.go (7k lines, 352kB)

R=golang-codereviews, bradfitz, iant
CC=golang-codereviews
https://golang.org/cl/42280045
This commit is contained in:
Russ Cox 2013-12-20 19:14:42 -05:00
parent 57e27a879e
commit 145edc283f
1 changed files with 29 additions and 18 deletions
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15
src/cmd/gc/plive.c
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@ -690,7 +690,7 @@ progeffects(Prog *prog, Array *vars, Bvec *uevar, Bvec *varkill)
// liveness computation. The cfg argument is an array of BasicBlock*s and the
// vars argument is an array of Node*s.
static Liveness*
newliveness(Node *fn, Prog *ptxt, Array *cfg, Array *vars)
newliveness(Node *fn, Prog *ptxt, Array *cfg, Array *vars, int computedead)
{
Liveness *result;
int32 i;
@ -719,8 +719,13 @@ newliveness(Node *fn, Prog *ptxt, Array *cfg, Array *vars)
result->livepointers = arraynew(0, sizeof(Bvec*));
result->argslivepointers = arraynew(0, sizeof(Bvec*));
if(computedead) {
result->deadvalues = arraynew(0, sizeof(Bvec*));
result->argsdeadvalues = arraynew(0, sizeof(Bvec*));
} else {
result->deadvalues = nil;
result->argsdeadvalues = nil;
}
return result;
}
@ -741,6 +746,7 @@ freeliveness(Liveness *lv)
free(*(Bvec**)arrayget(lv->argslivepointers, i));
arrayfree(lv->argslivepointers);
if(lv->deadvalues != nil) {
for(i = 0; i < arraylength(lv->deadvalues); i++)
free(*(Bvec**)arrayget(lv->deadvalues, i));
arrayfree(lv->deadvalues);
@ -748,6 +754,7 @@ freeliveness(Liveness *lv)
for(i = 0; i < arraylength(lv->argsdeadvalues); i++)
free(*(Bvec**)arrayget(lv->argsdeadvalues, i));
arrayfree(lv->argsdeadvalues);
}
for(i = 0; i < arraylength(lv->cfg); i++) {
free(lv->uevar[i]);
@ -1333,11 +1340,13 @@ livenessepilogue(Liveness *lv)
arrayadd(lv->livepointers, &locals);
// Dead stuff second.
if(lv->deadvalues != nil) {
args = bvalloc(argswords() * BitsPerPointer);
arrayadd(lv->argsdeadvalues, &args);
locals = bvalloc(localswords() * BitsPerPointer);
arrayadd(lv->deadvalues, &locals);
}
}
// walk backward, emit pcdata and populate the maps
pos = arraylength(lv->livepointers) - 1;
@ -1391,9 +1400,11 @@ livenessepilogue(Liveness *lv)
twobitlivepointermap(lv, liveout, lv->vars, args, locals);
// Record dead values.
if(lv->deadvalues != nil) {
args = *(Bvec**)arrayget(lv->argsdeadvalues, pos);
locals = *(Bvec**)arrayget(lv->deadvalues, pos);
twobitdeadvaluemap(lv, liveout, lv->vars, args, locals);
}
pos--;
}
@ -1487,7 +1498,7 @@ liveness(Node *fn, Prog *firstp, Sym *argssym, Sym *livesym, Sym *deadsym)
cfg = newcfg(firstp);
if(0) printcfg(cfg);
vars = getvariables(fn);
lv = newliveness(fn, firstp, cfg, vars);
lv = newliveness(fn, firstp, cfg, vars, deadsym != nil);
// Run the dataflow framework.
livenessprologue(lv);