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[turbofan] Remove WordEqual after WordAnd if it aims to test a bit.

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For Example:
------------------------
691:  Int32Constant[8]
1857: Word32And(1838,691)
1858: Word32Equal(1857,691)
1859: Branch(1858,2141)
======>
691:  Int32Constant[8]
1857: Word32And(1838,691)
1859: Branch(1857,2141)
------------------------


Assembly code:
------------------------
andl r9,0x8
cmpb r9l,0x8
jz 0x7f242017bf3c
======>
testb r9,0x8
jnz 0x7f56c017be2e
------------------------


Change-Id: I62a2a3d4bda5a82011b1c6aa745c1c8dc8cf4525
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3809052
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Commit-Queue: Jianxiao Lu <jianxiao.lu@intel.com>
Cr-Commit-Position: refs/heads/main@{#82508}
This commit is contained in:
JianxiaoLuIntel 2022-08-17 10:00:24 +08:00 committed by V8 LUCI CQ
parent 967a3b4847
commit da24d86a95
1 changed files with 52 additions and 0 deletions
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52
src/compiler/machine-operator-reducer.cc
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@ -2329,6 +2329,55 @@ base::Optional<SimplifiedCondition> TrySimplifyCompareZero(Node* cond) {
}
}
/*
Remove WordEqual after WordAnd if it aims to test a bit.
For Example:
------------------------
691: Int32Constant[8]
1857: Word32And(1838,691)
1858: Word32Equal(1857,691)
1859: Branch(1858,2141)
======>
691: Int32Constant[8]
1857: Word32And(1838,691)
1859: Branch(1857,2141)
------------------------
Assembly code:
------------------------
andl r9,0x8
cmpb r9l,0x8
jz 0x7f242017bf3c
======>
testb r9,0x8
jnz 0x7f56c017be2e
------------------------
*/
Node* TrySimplifyCompareForTestBit(Node* cond) {
if (cond->opcode() != IrOpcode::kWord32Equal) {
return nullptr;
}
Node* word_equal_left = cond->InputAt(0);
Node* word_equal_right = cond->InputAt(1);
if (word_equal_left->opcode() != IrOpcode::kWord32And ||
word_equal_right->opcode() != IrOpcode::kInt32Constant) {
return nullptr;
}
Node* word_and_right = word_equal_left->InputAt(1);
if (word_and_right->opcode() != IrOpcode::kInt32Constant) {
return nullptr;
}
int32_t a = OpParameter<int32_t>(word_and_right->op());
int32_t b = OpParameter<int32_t>(word_equal_right->op());
if (a != b || !base::bits::IsPowerOfTwo(a)) {
return nullptr;
}
DCHECK_EQ(word_equal_left->opcode(), IrOpcode::kWord32And);
return word_equal_left;
}
} // namespace
void MachineOperatorReducer::SwapBranches(Node* node) {
@ -2385,6 +2434,9 @@ Reduction MachineOperatorReducer::SimplifyBranch(Node* node) {
}
}
return Changed(node);
} else if (auto new_cond = TrySimplifyCompareForTestBit(cond)) {
node->ReplaceInput(0, new_cond);
return Changed(node);
}
return NoChange();
}