Reviewers: Vyacheslav Egorov, danno, Paul Lind, kisg,
Message:
This patch requires the following CL to be landed first:
https://chromiumcodereview.appspot.com/10874047
Description:
MIPS: Cleanup handling of shifts: SHR can deoptimize only when its a shift
by 0,
all other shift never deoptimize.
Port r12373 (9fdde2ad)
Original commit message:
Fix DoDeferredNumberTagU to keep the value in xmm1 instead of xmm0 on x64.
xmm0 is not saved across runtime call on x64 because
MacroAssembler::EnterExitFrameEpilogue preserves only allocatable XMM
registers
unlike on ia32 where it preserves all registers.
Cleanup handling of shifts: SHR can deoptimize only when its a shift by 0,
all
other shift never deoptimize.
Fix type inference for i-to-t change instruction. On X64 this ensures that
write-barrier is generated correctly.
BUG=
TEST=
Please review this at https://chromiumcodereview.appspot.com/10876054/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files:
M src/mips/lithium-mips.cc
Index: src/mips/lithium-mips.cc
diff --git a/src/mips/lithium-mips.cc b/src/mips/lithium-mips.cc
index
1c9859edd54cc1fb75a9591407d27b4011b7800b..0266f1375a22bfae0a46bc7e8ead0c045934f28f
100644
--- a/src/mips/lithium-mips.cc
+++ b/src/mips/lithium-mips.cc
@@ -713,15 +713,13 @@ LInstruction* LChunkBuilder::DoShift(Token::Value op,
right = UseRegisterAtStart(right_value);
}
+ // Shift operations can only deoptimize if we do a logical shift
+ // by 0 and the result cannot be truncated to int32.
bool does_deopt = false;
-
- if (FLAG_opt_safe_uint32_operations) {
- does_deopt = !instr->CheckFlag(HInstruction::kUint32);
- } else {
- // Shift operations can only deoptimize if we do a logical shift
- // by 0 and the result cannot be truncated to int32.
- bool may_deopt = (op == Token::SHR && constant_value == 0);
- if (may_deopt) {
+ if (op == Token::SHR && constant_value == 0) {
+ if (FLAG_opt_safe_uint32_operations) {
+ does_deopt = !instr->CheckFlag(HInstruction::kUint32);
+ } else {
for (HUseIterator it(instr->uses()); !it.Done(); it.Advance()) {
if (!it.value()->CheckFlag(HValue::kTruncatingToInt32)) {
does_deopt = true;
--
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