diff options
author | Keith Randall <khr@golang.org> | 2014-03-19 15:41:34 -0700 |
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committer | Keith Randall <khr@golang.org> | 2014-03-19 15:41:34 -0700 |
commit | ccf7f12e4bf8b78dab0b660ebe905309c91135dc (patch) | |
tree | 92d9b558118fb02cf4f40bca8bfb9f2ac4587a37 /src/cmd/6g | |
parent | e887b456832eabc461ca48906a08ecf4dfc9a358 (diff) | |
download | go-ccf7f12e4bf8b78dab0b660ebe905309c91135dc.tar.gz |
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://codereview.appspot.com/77920043
Diffstat (limited to 'src/cmd/6g')
-rw-r--r-- | src/cmd/6g/ggen.c | 26 |
1 files changed, 20 insertions, 6 deletions
diff --git a/src/cmd/6g/ggen.c b/src/cmd/6g/ggen.c index b046ac5a4..6dcf26303 100644 --- a/src/cmd/6g/ggen.c +++ b/src/cmd/6g/ggen.c @@ -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); } } |