[PATCH] D45510: [RFC][AliasAnalysis][BasicAA] Return MayAlias for the pointer plus variable offset to structure object member
Shiva Chen via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Thu Apr 12 17:23:49 PDT 2018
shiva0217 added a comment.
In https://reviews.llvm.org/D45510#1066136, @dberlin wrote:
> This C case is actually not legal (it's been discussed before many times).
> You cannot take the address of .a field, add an offset, and get to another field legally.
> So i wouldn't express it in these terms, since in that language, this is clearly illegal.
>
> The LLVM version, of course, does not make this undefined behavior AFAIK (which is a source of much imprecision)
Hi @dberlin. Thanks for the comments. So it's a language restriction which is illegal! Would you mind point me out which rule in C99 mention this restriction or the threads relative to this topic we could follow?
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https://reviews.llvm.org/D45510
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