[PATCH] D151631: [InstSimplify] Simplify select i1 ConstExpr, i1 true, i1 false to ConstExpr

[Nikita Popov via Phabricator via llvm-commits]

nikic added inline comments.


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Comment at: llvm/test/Transforms/InstSimplify/select-inseltpoison.ll:890
+;
+  %s = select i1 %a, i32 ptrtoint (ptr getelementptr inbounds ([3 x ptr], ptr @a, i64 0, i64 1) to i32), i32 undef
+  ret i32 %s
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khei4 wrote:
> I think 
> `i32 ptrtoint (ptr getelementptr inbounds ([3 x ptr], ptr @a, i64 0, i64 1) to i32)` doesn't produce poison. 
> index seems valid so maybe 
> `i32 ptrtoint (ptr getelementptr inbounds ([3 x ptr], ptr @a, i64 1, i64 0) to i32)` ?
Yes, strictly speaking this is also safe to fold, but would require analysis we don't currently do.

To make it actually poison you'd need something like `i32 ptrtoint (ptr getelementptr inbounds ([3 x ptr], ptr @a, i64 2) to i32)`.


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  https://reviews.llvm.org/D151631/new/

https://reviews.llvm.org/D151631