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[codegen] Remove redundant xorpd instructions

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It seems like they were originally added in https://crrev.com/23654026
(Sep 2013) to break dependences in the OOO pipeline. This code pattern
was then later copied for other instructions too
(https://crrev.com/1424333002).
The reason for the xorpd is not mentioned in the code though, and I
found no other compiler doing this. So maybe it's obsolete by now, and
only increases code size.

Let's remove them and see if we get any performance regressions.

R=ahaas@chromium.org
CC=yangguo@chromium.org

Change-Id: I0e6d65afa67f0ee286e5b0ba95c91092c5261c8f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1926427
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65077}
This commit is contained in:
Clemens Backes 2019-11-20 15:40:12 +01:00 committed by Commit Bot
parent 149f7f4d96
commit c4cf2ea4fd
2 changed files with 0 additions and 10 deletions
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2
src/codegen/ia32/macro-assembler-ia32.cc
View File

@ -511,12 +511,10 @@ void MacroAssembler::MaybeDropFrames() {
}
void TurboAssembler::Cvtsi2ss(XMMRegister dst, Operand src) {
xorps(dst, dst);
cvtsi2ss(dst, src);
}
void TurboAssembler::Cvtsi2sd(XMMRegister dst, Operand src) {
xorpd(dst, dst);
cvtsi2sd(dst, src);
}

8
src/codegen/x64/macro-assembler-x64.cc
View File

@ -736,10 +736,8 @@ void TurboAssembler::Cvtsd2ss(XMMRegister dst, Operand src) {
void TurboAssembler::Cvtlsi2sd(XMMRegister dst, Register src) {
if (CpuFeatures::IsSupported(AVX)) {
CpuFeatureScope scope(this, AVX);
vxorpd(dst, dst, dst);
vcvtlsi2sd(dst, dst, src);
} else {
xorpd(dst, dst);
cvtlsi2sd(dst, src);
}
}
@ -747,10 +745,8 @@ void TurboAssembler::Cvtlsi2sd(XMMRegister dst, Register src) {
void TurboAssembler::Cvtlsi2sd(XMMRegister dst, Operand src) {
if (CpuFeatures::IsSupported(AVX)) {
CpuFeatureScope scope(this, AVX);
vxorpd(dst, dst, dst);
vcvtlsi2sd(dst, dst, src);
} else {
xorpd(dst, dst);
cvtlsi2sd(dst, src);
}
}
@ -802,10 +798,8 @@ void TurboAssembler::Cvtqsi2ss(XMMRegister dst, Operand src) {
void TurboAssembler::Cvtqsi2sd(XMMRegister dst, Register src) {
if (CpuFeatures::IsSupported(AVX)) {
CpuFeatureScope scope(this, AVX);
vxorpd(dst, dst, dst);
vcvtqsi2sd(dst, dst, src);
} else {
xorpd(dst, dst);
cvtqsi2sd(dst, src);
}
}
@ -813,10 +807,8 @@ void TurboAssembler::Cvtqsi2sd(XMMRegister dst, Register src) {
void TurboAssembler::Cvtqsi2sd(XMMRegister dst, Operand src) {
if (CpuFeatures::IsSupported(AVX)) {
CpuFeatureScope scope(this, AVX);
vxorpd(dst, dst, dst);
vcvtqsi2sd(dst, dst, src);
} else {
xorpd(dst, dst);
cvtqsi2sd(dst, src);
}
}