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| author | Austin Clements <austin@google.com> | 2017-11-15 14:43:05 -0800 |
|---|---|---|
| committer | Austin Clements <austin@google.com> | 2017-11-17 01:00:05 +0000 |
| commit | bf9ad7080d0a22acf502a60d8bc6ebbc4f5340ef (patch) | |
| tree | 40997c9f0bfa940a9101d3952097335d3d95500e /src/runtime/asm_amd64.s | |
| parent | 366f46fe0084db6740b9db87dd36a52caf289025 (diff) | |
| download | go-bf9ad7080d0a22acf502a60d8bc6ebbc4f5340ef.tar.xz | |
runtime: remove another TODO
I experimented with having the compiler spill the two registers that
are clobbered by the write barrier fast path, but it slightly slows
down compilebench, which is a good write barrier benchmark:
name old time/op new time/op delta
Template 175ms ± 0% 176ms ± 1% ~ (p=0.393 n=10+10)
Unicode 83.6ms ± 1% 85.1ms ± 2% +1.79% (p=0.000 n=9+10)
GoTypes 585ms ± 0% 588ms ± 1% ~ (p=0.173 n=8+10)
Compiler 2.78s ± 1% 2.81s ± 2% +0.81% (p=0.023 n=10+10)
SSA 7.11s ± 1% 7.15s ± 1% +0.59% (p=0.029 n=10+10)
Flate 115ms ± 1% 116ms ± 2% ~ (p=0.853 n=10+10)
GoParser 144ms ± 2% 145ms ± 2% ~ (p=1.000 n=10+10)
Reflect 389ms ± 1% 390ms ± 1% ~ (p=0.481 n=10+10)
Tar 185ms ± 2% 185ms ± 2% ~ (p=0.529 n=10+10)
XML 205ms ± 0% 207ms ± 2% ~ (p=0.065 n=9+10)
Since this didn't pan out, remove the TODO.
Change-Id: I2186942c6d1ba10585a5da03cd7c1d26ce906273
Reviewed-on: https://go-review.googlesource.com/78034
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Rick Hudson <rlh@golang.org>
Diffstat (limited to 'src/runtime/asm_amd64.s')
| -rw-r--r-- | src/runtime/asm_amd64.s | 7 |
1 files changed, 2 insertions, 5 deletions
diff --git a/src/runtime/asm_amd64.s b/src/runtime/asm_amd64.s index 7e13458b0b..576a61ca6c 100644 --- a/src/runtime/asm_amd64.s +++ b/src/runtime/asm_amd64.s @@ -2380,11 +2380,8 @@ TEXT runtime·addmoduledata(SB),NOSPLIT,$0-0 // It clobbers FLAGS. It does not clobber any general-purpose registers, // but may clobber others (e.g., SSE registers). TEXT runtime·gcWriteBarrier(SB),NOSPLIT,$120 - // Save the registers clobbered by the fast path. - // - // TODO: Teach the register allocator that this clobbers some registers - // so we don't always have to save them? Use regs it's least likely to - // care about. + // Save the registers clobbered by the fast path. This is slightly + // faster than having the caller spill these. MOVQ R14, 104(SP) MOVQ R13, 112(SP) // TODO: Consider passing g.m.p in as an argument so they can be shared |