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ObjCARCContract: Use stripPointerCastsAndAliases #134275

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ObjCARCContract: Use stripPointerCastsAndAliases #134275

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de0d474
ObjCARCContract: Use stripPointerCastsAndAliases
arsenm Apr 3, 2025
cfd2525
Fix new test
arsenm Apr 12, 2025
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38 changes: 13 additions & 25 deletions llvm/lib/Transforms/ObjCARC/ObjCARCContract.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -660,31 +660,19 @@ bool ObjCARCContract::run(Function &F, AAResults *A, DominatorTree *D) {
};

Value *Arg = cast<CallInst>(Inst)->getArgOperand(0);

// TODO: Change this to a do-while.
for (;;) {
ReplaceArgUses(Arg);

// If Arg is a no-op casted pointer, strip one level of casts and iterate.
if (const BitCastInst *BI = dyn_cast<BitCastInst>(Arg))
Arg = BI->getOperand(0);
else if (isa<GEPOperator>(Arg) &&
cast<GEPOperator>(Arg)->hasAllZeroIndices())
Arg = cast<GEPOperator>(Arg)->getPointerOperand();
else if (isa<GlobalAlias>(Arg) &&
!cast<GlobalAlias>(Arg)->isInterposable())
Arg = cast<GlobalAlias>(Arg)->getAliasee();
else {
// If Arg is a PHI node, get PHIs that are equivalent to it and replace
// their uses.
if (PHINode *PN = dyn_cast<PHINode>(Arg)) {
SmallVector<Value *, 1> PHIList;
getEquivalentPHIs(*PN, PHIList);
for (Value *PHI : PHIList)
ReplaceArgUses(PHI);
}
break;
}
ReplaceArgUses(Arg);

Value *Stripped = Arg->stripPointerCastsAndAliases();
if (Stripped != Arg)
ReplaceArgUses(Stripped);

// If Arg is a PHI node, get PHIs that are equivalent to it and replace
// their uses.
if (PHINode *PN = dyn_cast<PHINode>(Stripped)) {
SmallVector<Value *, 1> PHIList;
getEquivalentPHIs(*PN, PHIList);
for (Value *PHI : PHIList)
ReplaceArgUses(PHI);
}
}

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16 changes: 16 additions & 0 deletions llvm/test/Transforms/ObjCARC/contract.ll
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Expand Up @@ -234,6 +234,22 @@ define void @test14(ptr %a, ptr %b) {
ret void
}

define void @test15(ptr %x) {
; CHECK-LABEL: define void @test15(
; CHECK-SAME: ptr [[X:%.*]]) {
; CHECK-NEXT: [[Y:%.*]] = getelementptr inbounds ptr, ptr [[X]], i32 0
; CHECK-NEXT: [[V0:%.*]] = call ptr @llvm.objc.retain(ptr [[Y]]) #[[ATTR0:[0-9]+]]
; CHECK-NEXT: call void @use_pointer(ptr [[V0]])
; CHECK-NEXT: call void @use_pointer(ptr [[V0]])
; CHECK-NEXT: ret void
;
%y = getelementptr inbounds ptr, ptr %x, i32 0
%v0 = call ptr @llvm.objc.retain(ptr %y) nounwind
call void @use_pointer(ptr %x)
call void @use_pointer(ptr %y)
ret void
}

declare void @llvm.objc.clang.arc.use(...) nounwind
declare void @llvm.objc.clang.arc.noop.use(...) nounwind

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