Reviewers: Yang,
Message:
PTAL
I'm not sure if param src of LoadUint32() is guaranteed to have upper half
zeroed?
Description:
Small improvement in x64 assembler
Please review this at https://codereview.chromium.org/12177012/
SVN Base: http://v8.googlecode.com/svn/branches/bleeding_edge/
Affected files:
M src/x64/assembler-x64.cc
M src/x64/macro-assembler-x64.cc
Index: src/x64/assembler-x64.cc
===================================================================
--- src/x64/assembler-x64.cc (revision 13579)
+++ src/x64/assembler-x64.cc (working copy)
@@ -1505,13 +1505,12 @@
void Assembler::movq(Register dst, int64_t value, RelocInfo::Mode rmode) {
// Non-relocatable values might not need a 64-bit representation.
if (RelocInfo::IsNone(rmode)) {
- // Sadly, there is no zero or sign extending move for 8-bit immediates.
- if (is_int32(value)) {
- movq(dst, Immediate(static_cast<int32_t>(value)));
- return;
- } else if (is_uint32(value)) {
+ if (is_uint32(value)) {
movl(dst, Immediate(static_cast<int32_t>(value)));
return;
+ } else if (is_int32(value)) {
+ movq(dst, Immediate(static_cast<int32_t>(value)));
+ return;
}
// Value cannot be represented by 32 bits, so do a full 64 bit
immediate
// value.
Index: src/x64/macro-assembler-x64.cc
===================================================================
--- src/x64/macro-assembler-x64.cc (revision 13579)
+++ src/x64/macro-assembler-x64.cc (working copy)
@@ -2911,23 +2911,14 @@
}
-static double kUint32Bias =
- static_cast<double>(static_cast<uint32_t>(0xFFFFFFFF)) + 1;
-
-
void MacroAssembler::LoadUint32(XMMRegister dst,
Register src,
XMMRegister scratch) {
- Label done;
- cmpl(src, Immediate(0));
- movq(kScratchRegister,
- reinterpret_cast<int64_t>(&kUint32Bias),
- RelocInfo::NONE64);
- movsd(scratch, Operand(kScratchRegister, 0));
- cvtlsi2sd(dst, src);
- j(not_sign, &done, Label::kNear);
- addsd(dst, scratch);
- bind(&done);
+ if (FLAG_debug_code) {
+ cmpq(src, Immediate(0xffffffff));
+ Assert(below_equal, "input GPR is expected to have upper32 cleared");
+ }
+ cvtqsi2sd(dst, src);
}
--
--
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