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[SimplifyCFG] Fix if conversion with opaque pointers

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We need to make sure that the value types are the same. Otherwise
we both may not have the necessary dereferenceability implication,
nor can we directly form the desired select pattern.

Without opaque pointers this is enforced implicitly through the
pointer comparison.
This commit is contained in:
Nikita Popov 2021-07-21 22:22:26 +02:00
parent f265bf7812
commit 5d9c2de528
2 changed files with 24 additions and 1 deletions
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4
lib/Transforms/Utils/SimplifyCFG.cpp
View File

@ -2228,6 +2228,7 @@ static Value *isSafeToSpeculateStore(Instruction *I, BasicBlock *BrBB,
return nullptr;
Value *StorePtr = StoreToHoist->getPointerOperand();
Type *StoreTy = StoreToHoist->getValueOperand()->getType();
// Look for a store to the same pointer in BrBB.
unsigned MaxNumInstToLookAt = 9;
@ -2244,7 +2245,8 @@ static Value *isSafeToSpeculateStore(Instruction *I, BasicBlock *BrBB,
if (auto *SI = dyn_cast<StoreInst>(&CurI)) {
// Found the previous store make sure it stores to the same location.
if (SI->getPointerOperand() == StorePtr)
if (SI->getPointerOperand() == StorePtr &&
SI->getValueOperand()->getType() == StoreTy)
// Found the previous store, return its value operand.
return SI->getValueOperand();
return nullptr; // Unknown store.

21
test/Transforms/SimplifyCFG/speculate-store.ll
View File

@ -112,6 +112,27 @@ ret.end:
ret void
}
define void @different_type(ptr %ptr, i1 %cmp) {
; CHECK-LABEL: @different_type(
; CHECK-NEXT: store i32 0, ptr [[PTR:%.*]], align 4
; CHECK-NEXT: br i1 [[CMP:%.*]], label [[IF_THEN:%.*]], label [[RET_END:%.*]]
; CHECK: if.then:
; CHECK-NEXT: store i64 1, ptr [[PTR]], align 4
; CHECK-NEXT: br label [[RET_END]]
; CHECK: ret.end:
; CHECK-NEXT: ret void
;
store i32 0, ptr %ptr
br i1 %cmp, label %if.then, label %ret.end
if.then:
store i64 1, ptr %ptr
br label %ret.end
ret.end:
ret void
}
; CHECK: !0 = !{!"branch_weights", i32 3, i32 5}
!0 = !{!"branch_weights", i32 3, i32 5}