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[x64] Replace movl_subl instruction with leal

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This eliminates one instruction for following pattern:
  movl rX, rY       // TruncateInt64ToInt32
  subl rX, imm32
==>
  leal rX, [rY - imm32]

R=bmeurer@chromium.org

Change-Id: I4164e1407f5953302051e905555da14d3ca6680a
Reviewed-on: https://chromium-review.googlesource.com/1046381
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Kanghua Yu <kanghua.yu@intel.com>
Cr-Commit-Position: refs/heads/master@{#53021}
This commit is contained in:
Kanghua Yu 2018-05-07 15:04:53 +08:00 committed by Commit Bot
parent 6380476c71
commit aa6e58ce9d
1 changed files with 13 additions and 0 deletions
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13
src/compiler/x64/instruction-selector-x64.cc
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@ -832,6 +832,19 @@ void InstructionSelector::VisitInt64AddWithOverflow(Node* node) {
void InstructionSelector::VisitInt32Sub(Node* node) {
X64OperandGenerator g(this);
DCHECK_EQ(node->InputCount(), 2);
Node* input1 = node->InputAt(0);
Node* input2 = node->InputAt(1);
if (input1->opcode() == IrOpcode::kTruncateInt64ToInt32 &&
g.CanBeImmediate(input2)) {
// Omit truncation and turn subtractions of constant values into immediate
// "leal" instructions by negating the value.
Emit(kX64Lea32 | AddressingModeField::encode(kMode_MRI),
g.DefineAsRegister(node), g.UseRegister(input1->InputAt(0)),
g.TempImmediate(-g.GetImmediateIntegerValue(input2)));
return;
}
Int32BinopMatcher m(node);
if (m.left().Is(0)) {
Emit(kX64Neg32, g.DefineSameAsFirst(node), g.UseRegister(m.right().node()));