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[arm] Fix UBFX detection.

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R=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/725063002

Cr-Commit-Position: refs/heads/master@{#25344}
This commit is contained in:
Benedikt Meurer 2014-11-14 08:43:40 +01:00
parent 05e921433e
commit 1514287a28
1 changed files with 19 additions and 11 deletions
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30
src/compiler/arm/instruction-selector-arm.cc
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@ -368,6 +368,16 @@ void EmitBic(InstructionSelector* selector, Node* node, Node* left,
g.UseRegister(right));
}
void EmitUbfx(InstructionSelector* selector, Node* node, Node* left,
uint32_t lsb, uint32_t width) {
DCHECK_LE(1, width);
DCHECK_LE(width, 32 - lsb);
ArmOperandGenerator g(selector);
selector->Emit(kArmUbfx, g.DefineAsRegister(node), g.UseRegister(left),
g.TempImmediate(lsb), g.TempImmediate(width));
}
} // namespace
@ -398,15 +408,16 @@ void InstructionSelector::VisitWord32And(Node* node) {
if (m.left().IsWord32Shr()) {
Int32BinopMatcher mleft(m.left().node());
if (mleft.right().IsInRange(0, 31)) {
Emit(kArmUbfx, g.DefineAsRegister(node),
g.UseRegister(mleft.left().node()),
g.UseImmediate(mleft.right().node()), g.TempImmediate(width));
return;
// UBFX cannot extract bits past the register size, however since
// shifting the original value would have introduced some zeros we can
// still use UBFX with a smaller mask and the remaining bits will be
// zeros.
uint32_t const lsb = mleft.right().Value();
return EmitUbfx(this, node, mleft.left().node(), lsb,
std::min(width, 32 - lsb));
}
}
Emit(kArmUbfx, g.DefineAsRegister(node), g.UseRegister(m.left().node()),
g.TempImmediate(0), g.TempImmediate(width));
return;
return EmitUbfx(this, node, m.left().node(), 0, width);
}
// Try to interpret this AND as BIC.
if (g.CanBeImmediate(~value)) {
@ -523,10 +534,7 @@ void InstructionSelector::VisitWord32Shr(Node* node) {
uint32_t msb = base::bits::CountLeadingZeros32(value);
if (msb + width + lsb == 32) {
DCHECK_EQ(lsb, base::bits::CountTrailingZeros32(value));
Emit(kArmUbfx, g.DefineAsRegister(node),
g.UseRegister(mleft.left().node()), g.TempImmediate(lsb),
g.TempImmediate(width));
return;
return EmitUbfx(this, node, mleft.left().node(), lsb, width);
}
}
}