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[EarlyCSE] Use m_LogicalAnd/Or matchers to handle branch conditions

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EarlyCSE's handleBranchCondition says:

```
// If the condition is AND operation, we can propagate its operands into the
// true branch. If it is OR operation, we can propagate them into the false
// branch.
```

This holds for the corresponding select patterns as well.

This is a part of an ongoing work for disabling buggy select->and/or transformations.
See llvm.org/pr48353 and D93065 for more context

Proof:
and: https://alive2.llvm.org/ce/z/MQWodU
or: https://alive2.llvm.org/ce/z/9GLbB_

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D93842
This commit is contained in:
Juneyoung Lee 2020-12-28 05:36:26 +09:00
parent 5e880dcc6f
commit fb0fe9dd48
2 changed files with 15 additions and 13 deletions
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16
lib/Transforms/Scalar/EarlyCSE.cpp
View File

@ -1033,9 +1033,14 @@ bool EarlyCSE::handleBranchCondition(Instruction *CondInst,
auto *TorF = (BI->getSuccessor(0) == BB)
? ConstantInt::getTrue(BB->getContext())
: ConstantInt::getFalse(BB->getContext());
auto MatchBinOp = [](Instruction *I, unsigned Opcode) {
if (BinaryOperator *BOp = dyn_cast<BinaryOperator>(I))
return BOp->getOpcode() == Opcode;
auto MatchBinOp = [](Instruction *I, unsigned Opcode, Value *&LHS,
Value *&RHS) {
if (Opcode == Instruction::And &&
match(I, m_LogicalAnd(m_Value(LHS), m_Value(RHS))))
return true;
else if (Opcode == Instruction::Or &&
match(I, m_LogicalOr(m_Value(LHS), m_Value(RHS))))
return true;
return false;
};
// If the condition is AND operation, we can propagate its operands into the
@ -1066,8 +1071,9 @@ bool EarlyCSE::handleBranchCondition(Instruction *CondInst,
}
}
if (MatchBinOp(Curr, PropagateOpcode))
for (auto &Op : cast<BinaryOperator>(Curr)->operands())
Value *LHS, *RHS;
if (MatchBinOp(Curr, PropagateOpcode, LHS, RHS))
for (auto &Op : { LHS, RHS })
if (Instruction *OPI = dyn_cast<Instruction>(Op))
if (SimpleValue::canHandle(OPI) && Visited.insert(OPI).second)
WorkList.push_back(OPI);

12
test/Transforms/EarlyCSE/and_or.ll
View File

@ -62,8 +62,7 @@ define i32 @test_02_select(i32 %a, i32 %b, i1 %c) {
; CHECK-NEXT: [[AND_COND:%.*]] = select i1 [[COND]], i1 [[C:%.*]], i1 false
; CHECK-NEXT: br i1 [[AND_COND]], label [[IF_TRUE:%.*]], label [[IF_FALSE:%.*]]
; CHECK: if.true:
; CHECK-NEXT: [[X:%.*]] = select i1 [[COND]], i32 [[A]], i32 [[B]]
; CHECK-NEXT: ret i32 [[X]]
; CHECK-NEXT: ret i32 [[A]]
; CHECK: if.false:
; CHECK-NEXT: [[Y:%.*]] = select i1 [[COND]], i32 [[A]], i32 [[B]]
; CHECK-NEXT: ret i32 [[Y]]
@ -122,8 +121,7 @@ define i32 @test_03_select(i32 %a, i32 %b, i1 %c) {
; CHECK-NEXT: [[X:%.*]] = select i1 [[COND]], i32 [[A]], i32 [[B]]
; CHECK-NEXT: ret i32 [[X]]
; CHECK: if.false:
; CHECK-NEXT: [[Y:%.*]] = select i1 [[COND]], i32 [[A]], i32 [[B]]
; CHECK-NEXT: ret i32 [[Y]]
; CHECK-NEXT: ret i32 [[B]]
;
entry:
%cond = icmp slt i32 %a, %b
@ -179,8 +177,7 @@ define i32 @test_04_select(i32 %a, i32 %b, i1 %c1, i1 %c2) {
; CHECK-NEXT: [[AND_COND2:%.*]] = select i1 [[AND_COND1]], i1 [[C2:%.*]], i1 false
; CHECK-NEXT: br i1 [[AND_COND2]], label [[IF_TRUE:%.*]], label [[IF_FALSE:%.*]]
; CHECK: if.true:
; CHECK-NEXT: [[X:%.*]] = select i1 [[COND]], i32 [[A]], i32 [[B]]
; CHECK-NEXT: ret i32 [[X]]
; CHECK-NEXT: ret i32 [[A]]
; CHECK: if.false:
; CHECK-NEXT: [[Y:%.*]] = select i1 [[COND]], i32 [[A]], i32 [[B]]
; CHECK-NEXT: ret i32 [[Y]]
@ -243,8 +240,7 @@ define i32 @test_05_select(i32 %a, i32 %b, i1 %c1, i1 %c2) {
; CHECK-NEXT: [[X:%.*]] = select i1 [[COND]], i32 [[A]], i32 [[B]]
; CHECK-NEXT: ret i32 [[X]]
; CHECK: if.false:
; CHECK-NEXT: [[Y:%.*]] = select i1 [[COND]], i32 [[A]], i32 [[B]]
; CHECK-NEXT: ret i32 [[Y]]
; CHECK-NEXT: ret i32 [[B]]
;
entry:
%cond = icmp slt i32 %a, %b