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[x64] Remove unnecessary WordAnd in WordCompare

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If the WordAnd aims to take low 8/16/32 bits of an oprand for later cmp8/cmp16/cmp32, it can be removed.

Change-Id: I0040e596ab65a6a9255ddbdb4fca573fd765879e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3731488
Commit-Queue: Jianxiao Lu <jianxiao.lu@intel.com>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81473}
This commit is contained in:
JianxiaoLuIntel 2022-06-30 20:38:34 +08:00 committed by V8 LUCI CQ
parent 1f97a2dfcb
commit c651551f26
1 changed files with 61 additions and 0 deletions
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61
src/compiler/backend/x64/instruction-selector-x64.cc
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@ -2267,6 +2267,63 @@ InstructionCode TryNarrowOpcodeSize(InstructionCode opcode, Node* left,
return opcode;
}
/*
Remove unnecessary WordAnd
For example:
33: IfFalse(31)
517: Int32Constant[65535]
518: Word32And(18, 517)
36: Int32Constant[266]
37: Int32LessThanOrEqual(36, 518)
38: Branch[None]
If Int32LessThanOrEqual select cmp16, the above Word32And can be removed:
33: IfFalse(31)
36: Int32Constant[266]
37: Int32LessThanOrEqual(36, 18)
38: Branch[None]
*/
void RemoveUnnecessaryWordAnd(InstructionCode opcode, Node** and_node) {
int64_t mask = 0;
if (opcode == kX64Cmp32 || opcode == kX64Test32) {
mask = std::numeric_limits<uint32_t>::max();
} else if (opcode == kX64Cmp16 || opcode == kX64Test16) {
mask = std::numeric_limits<uint16_t>::max();
} else if (opcode == kX64Cmp8 || opcode == kX64Test8) {
mask = std::numeric_limits<uint8_t>::max();
} else {
return;
}
Node* and_left = (*and_node)->InputAt(0);
Node* and_right = (*and_node)->InputAt(1);
Node* and_constant_node = nullptr;
Node* and_other_node = nullptr;
if (IsIntConstant(and_left)) {
and_constant_node = and_left;
and_other_node = and_right;
} else if (IsIntConstant(and_right)) {
and_constant_node = and_right;
and_other_node = and_left;
}
if (and_constant_node) {
int64_t and_constant;
if (and_constant_node->opcode() == IrOpcode::kInt32Constant) {
and_constant = OpParameter<int32_t>(and_constant_node->op());
} else if (and_constant_node->opcode() == IrOpcode::kInt64Constant) {
and_constant = OpParameter<int64_t>(and_constant_node->op());
} else {
UNREACHABLE();
}
if (and_constant == mask) {
*and_node = and_other_node;
}
}
}
// Shared routine for multiple word compare operations.
void VisitWordCompare(InstructionSelector* selector, Node* node,
InstructionCode opcode, FlagsContinuation* cont) {
@ -2299,6 +2356,10 @@ void VisitWordCompare(InstructionSelector* selector, Node* node,
std::swap(left, right);
}
if (IsWordAnd(left)) {
RemoveUnnecessaryWordAnd(opcode, &left);
}
// Match immediates on right side of comparison.
if (g.CanBeImmediate(right)) {
if (g.CanBeMemoryOperand(opcode, node, left, effect_level)) {