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cmd/6g: do small zeroings with straightline code. 

Removes most uses of the REP prefix, which has a high startup cost.

LGTM=iant
R=golang-codereviews, iant, khr
CC=golang-codereviews
https://golang.org/cl/77920043
This commit is contained in:
Keith Randall 2014-03-19 15:41:34 -07:00
parent b00d967706
commit 14664050b9
2 changed files with 35 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
src/cmd/6g/ggen.c
View File

@ -16,6 +16,7 @@ defframe(Prog *ptxt)
{
uint32 frame;
Prog *p;
vlong i;
// fill in argument size
ptxt->to.offset = rnd(curfn->type->argwid, widthptr);
@ -29,12 +30,25 @@ defframe(Prog *ptxt)
// so that garbage collector only sees initialized values
// when it looks for pointers.
p = ptxt;
if(stkzerosize > 0) {
p = appendpp(p, movptr, D_CONST, 0, D_AX, 0);
p = appendpp(p, movptr, D_CONST, stkzerosize/widthptr, D_CX, 0);
p = appendpp(p, leaptr, D_SP+D_INDIR, frame-stkzerosize, D_DI, 0);
p = appendpp(p, AREP, D_NONE, 0, D_NONE, 0);
appendpp(p, stosptr, D_NONE, 0, D_NONE, 0);
if(stkzerosize % widthreg != 0)
fatal("zero size not a multiple of ptr size");
if(stkzerosize == 0) {
// nothing
} else if(stkzerosize <= 2*widthreg) {
for(i = 0; i < stkzerosize; i += widthreg) {
p = appendpp(p, AMOVQ, D_CONST, 0, D_SP+D_INDIR, frame-stkzerosize+i);
}
} else if(stkzerosize <= 16*widthreg) {
p = appendpp(p, AMOVQ, D_CONST, 0, D_AX, 0);
for(i = 0; i < stkzerosize; i += widthreg) {
p = appendpp(p, AMOVQ, D_AX, 0, D_SP+D_INDIR, frame-stkzerosize+i);
}
} else {
p = appendpp(p, AMOVQ, D_CONST, 0, D_AX, 0);
p = appendpp(p, AMOVQ, D_CONST, stkzerosize/widthreg, D_CX, 0);
p = appendpp(p, leaptr, D_SP+D_INDIR, frame-stkzerosize, D_DI, 0);
p = appendpp(p, AREP, D_NONE, 0, D_NONE, 0);
appendpp(p, ASTOSQ, D_NONE, 0, D_NONE, 0);
}
}

16
src/cmd/8g/ggen.c
View File

@ -16,6 +16,7 @@ defframe(Prog *ptxt)
{
uint32 frame;
Prog *p;
vlong i;
// fill in argument size
ptxt->to.offset2 = rnd(curfn->type->argwid, widthptr);
@ -28,7 +29,20 @@ defframe(Prog *ptxt)
// so that garbage collector only sees initialized values
// when it looks for pointers.
p = ptxt;
if(stkzerosize > 0) {
if(stkzerosize % widthptr != 0)
fatal("zero size not a multiple of ptr size");
if(stkzerosize == 0) {
// nothing
} else if(stkzerosize <= 2*widthptr) {
for(i = 0; i < stkzerosize; i += widthptr) {
p = appendpp(p, AMOVL, D_CONST, 0, D_SP+D_INDIR, frame-stkzerosize+i);
}
} else if(stkzerosize <= 16*widthptr) {
p = appendpp(p, AMOVL, D_CONST, 0, D_AX, 0);
for(i = 0; i < stkzerosize; i += widthptr) {
p = appendpp(p, AMOVL, D_AX, 0, D_SP+D_INDIR, frame-stkzerosize+i);
}
} else {
p = appendpp(p, AMOVL, D_CONST, 0, D_AX, 0);
p = appendpp(p, AMOVL, D_CONST, stkzerosize/widthptr, D_CX, 0);
p = appendpp(p, ALEAL, D_SP+D_INDIR, frame-stkzerosize, D_DI, 0);