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[SimplifyCFG] Switch to use paramHasNonNullAttr #125383

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Merged
dtcxzyw merged 2 commits into from
Jun 2, 2025
Merged

[SimplifyCFG] Switch to use paramHasNonNullAttr #125383

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5b59246
[SimplifyCFG] Switch to use `paramHasNonNullAttr`
dtcxzyw Feb 2, 2025
49bc007
[IR] Only check attributes
dtcxzyw Jun 1, 2025
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12 changes: 10 additions & 2 deletions llvm/include/llvm/IR/InstrTypes.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1839,7 +1839,11 @@ class CallBase : public Instruction {
/// Extract the number of dereferenceable bytes for a call or
/// parameter (0=unknown).
uint64_t getParamDereferenceableBytes(unsigned i) const {
return Attrs.getParamDereferenceableBytes(i);
uint64_t Bytes = Attrs.getParamDereferenceableBytes(i);
if (const Function *F = getCalledFunction())
Bytes =
std::max(Bytes, F->getAttributes().getParamDereferenceableBytes(i));
return Bytes;
}

/// Extract the number of dereferenceable_or_null bytes for a call
Expand All @@ -1857,7 +1861,11 @@ class CallBase : public Instruction {
/// Extract the number of dereferenceable_or_null bytes for a
/// parameter (0=unknown).
uint64_t getParamDereferenceableOrNullBytes(unsigned i) const {
return Attrs.getParamDereferenceableOrNullBytes(i);
uint64_t Bytes = Attrs.getParamDereferenceableOrNullBytes(i);
if (const Function *F = getCalledFunction())
Bytes = std::max(
Bytes, F->getAttributes().getParamDereferenceableOrNullBytes(i));
return Bytes;
}

/// Extract a test mask for disallowed floating-point value classes for the
Expand Down
4 changes: 2 additions & 2 deletions llvm/lib/Transforms/Utils/SimplifyCFG.cpp
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Expand Up @@ -8224,8 +8224,8 @@ static bool passingValueIsAlwaysUndefined(Value *V, Instruction *I, bool PtrValu
if (CB->isArgOperand(&Use)) {
unsigned ArgIdx = CB->getArgOperandNo(&Use);
// Passing null to a nonnnull+noundef argument is undefined.
if (C->isNullValue() && CB->isPassingUndefUB(ArgIdx) &&
CB->paramHasAttr(ArgIdx, Attribute::NonNull))
if (isa<ConstantPointerNull>(C) &&
CB->paramHasNonNullAttr(ArgIdx, /*AllowUndefOrPoison=*/false))
return !PtrValueMayBeModified;
// Passing undef to a noundef argument is undefined.
if (isa<UndefValue>(C) && CB->isPassingUndefUB(ArgIdx))
Expand Down
11 changes: 5 additions & 6 deletions llvm/test/Transforms/SimplifyCFG/UnreachableEliminate.ll
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Expand Up @@ -238,7 +238,7 @@ else:
}

declare ptr @fn_nonnull_noundef_arg(ptr nonnull noundef %p)
declare ptr @fn_nonnull_deref_arg(ptr nonnull dereferenceable(4) %p)
declare ptr @fn_deref_arg(ptr dereferenceable(4) %p)
declare ptr @fn_nonnull_deref_or_null_arg(ptr nonnull dereferenceable_or_null(4) %p)
declare ptr @fn_nonnull_arg(ptr nonnull %p)
declare ptr @fn_noundef_arg(ptr noundef %p)
Expand Down Expand Up @@ -271,7 +271,7 @@ define void @test9_deref(i1 %X, ptr %Y) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = xor i1 [[X:%.*]], true
; CHECK-NEXT: call void @llvm.assume(i1 [[TMP0]])
; CHECK-NEXT: [[TMP1:%.*]] = call ptr @fn_nonnull_deref_arg(ptr [[Y:%.*]])
; CHECK-NEXT: [[TMP1:%.*]] = call ptr @fn_deref_arg(ptr [[Y:%.*]])
; CHECK-NEXT: ret void
;
entry:
Expand All @@ -282,17 +282,16 @@ if:

else:
%phi = phi ptr [ %Y, %entry ], [ null, %if ]
call ptr @fn_nonnull_deref_arg(ptr %phi)
call ptr @fn_deref_arg(ptr %phi)
ret void
}

; Optimizing this code should produce assume.
define void @test9_deref_or_null(i1 %X, ptr %Y) {
; CHECK-LABEL: @test9_deref_or_null(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = xor i1 [[X:%.*]], true
; CHECK-NEXT: call void @llvm.assume(i1 [[TMP0]])
; CHECK-NEXT: [[TMP1:%.*]] = call ptr @fn_nonnull_deref_or_null_arg(ptr [[Y:%.*]])
; CHECK-NEXT: [[Y:%.*]] = select i1 [[X:%.*]], ptr null, ptr [[Y1:%.*]]
; CHECK-NEXT: [[TMP1:%.*]] = call ptr @fn_nonnull_deref_or_null_arg(ptr [[Y]])
; CHECK-NEXT: ret void
;
entry:
Expand Down
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