[PATCH] D100141: [nofree] Restrict semantics to memory visible to caller

[Johannes Doerfert via Phabricator via llvm-commits]

jdoerfert added a comment.

In D100141#2697374 <https://reviews.llvm.org/D100141#2697374>, @nlopes wrote:

> I've updated Alive2 with the new semantics and I see one regression:
> `llvm/test/Transforms/InstCombine/malloc-free-delete.ll`
>
>   define void @test14(* %foo) nofree {
>     free * %foo
>     ret void
>   }
>   =>
>   define void @test14(* %foo) nofree {
>     call void #trap() nowrite noreturn
>     assume i1 0
>   }
>   
>   Transformation doesn't verify!
>   
>   ERROR: Source is more defined than target
>   
>   Example:
>   * %foo = null
>
> free(null) is a no-op, so I think the test case is buggy. This transformation can only be done if the argument is non-null.

Right, the transformation should be `llvm.assume(%foo == null)`.


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https://reviews.llvm.org/D100141