Reviewers: dcarney,
Description:
[x64] Improve materialization of certain double constants (i.e. -0.0).
[email protected]
Please review this at https://codereview.chromium.org/946423003/
Base URL: https://chromium.googlesource.com/v8/v8.git@master
Affected files (+30, -11 lines):
M src/x64/macro-assembler-x64.cc
Index: src/x64/macro-assembler-x64.cc
diff --git a/src/x64/macro-assembler-x64.cc b/src/x64/macro-assembler-x64.cc
index
295f89106f1dac07c3a62f585c9c922b0502be0c..86915e951b729c77d152542c692ee445fedcc6b7
100644
--- a/src/x64/macro-assembler-x64.cc
+++ b/src/x64/macro-assembler-x64.cc
@@ -2578,24 +2578,43 @@ void MacroAssembler::Move(XMMRegister dst, uint32_t
src) {
if (src == 0) {
xorps(dst, dst);
} else {
- movl(kScratchRegister, Immediate(src));
- movq(dst, kScratchRegister);
+ unsigned pop = base::bits::CountPopulation32(src);
+ DCHECK_NE(0u, pop);
+ if (pop == 32) {
+ pcmpeqd(dst, dst);
+ } else {
+ movl(kScratchRegister, Immediate(src));
+ movq(dst, kScratchRegister);
+ }
}
}
void MacroAssembler::Move(XMMRegister dst, uint64_t src) {
- uint32_t lower = static_cast<uint32_t>(src);
- uint32_t upper = static_cast<uint32_t>(src >> 32);
- if (upper == 0) {
- Move(dst, lower);
+ if (src == 0) {
+ xorps(dst, dst);
} else {
- if (lower == 0) {
- Move(dst, upper);
- psllq(dst, 32);
+ unsigned nlz = base::bits::CountLeadingZeros64(src);
+ unsigned ntz = base::bits::CountTrailingZeros64(src);
+ unsigned pop = base::bits::CountPopulation64(src);
+ DCHECK_NE(0u, pop);
+ if (pop == 64) {
+ pcmpeqd(dst, dst);
+ } else if (pop + ntz == 64) {
+ pcmpeqd(dst, dst);
+ psllq(dst, ntz);
+ } else if (pop + nlz == 64) {
+ pcmpeqd(dst, dst);
+ psrlq(dst, nlz);
} else {
- movq(kScratchRegister, src);
- movq(dst, kScratchRegister);
+ uint32_t lower = static_cast<uint32_t>(src);
+ uint32_t upper = static_cast<uint32_t>(src >> 32);
+ if (upper == 0) {
+ Move(dst, lower);
+ } else {
+ movq(kScratchRegister, src);
+ movq(dst, kScratchRegister);
+ }
}
}
}
--
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