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[IR] Only require nofree in canBeFreed() #200191

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Merged
nikic merged 1 commit into from
May 29, 2026
Merged

[IR] Only require nofree in canBeFreed() #200191

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11 changes: 5 additions & 6 deletions llvm/lib/IR/Value.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -834,13 +834,12 @@ bool Value::canBeFreed() const {
if (auto *A = dyn_cast<Argument>(this)) {
if (A->hasPointeeInMemoryValueAttr())
return false;
// A pointer to an object in a function which neither frees, nor can arrange
// for another thread to free on its behalf, can not be freed in the scope
// of the function. Note that this logic is restricted to memory
// allocations in existance before the call; a nofree function *is* allowed
// to free memory it allocated.
// A nofree function can not free (including via synchronization) any
// allocations that existed prior to the call, but may free allocations
// created inside the function. This logic is limited to argument pointers,
// as they definitely exist prior to the call.
const Function *F = A->getParent();
if (F->doesNotFreeMemory() && F->hasNoSync())
if (F->doesNotFreeMemory())
return false;
}

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6 changes: 2 additions & 4 deletions llvm/test/Analysis/ValueTracking/memory-dereferenceable.ll
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Expand Up @@ -248,16 +248,14 @@ define void @negative(ptr dereferenceable(8) %p) {

; CHECK-LABEL: 'infer_func_attrs1'
; CHECK: %p
define void @infer_func_attrs1(ptr dereferenceable(8) %p) nofree nosync {
define void @infer_func_attrs1(ptr dereferenceable(8) %p) nofree {
call void @mayfree()
%v = load i32, ptr %p
ret void
}

; CHECK-LABEL: 'infer_func_attrs2'
; GLOBAL: %p
; POINT-NOT: %p
; FIXME: Can be inferred from attributes
; CHECK: %p
define void @infer_func_attrs2(ptr dereferenceable(8) %p) readonly {
call void @mayfree()
%v = load i32, ptr %p
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