[PATCH] D78922: [CostModel] Remove getExtCost

[Sam Parker via Phabricator via llvm-commits]

samparker marked an inline comment as done.
samparker added inline comments.


================
Comment at: llvm/include/llvm/CodeGen/BasicTTIImpl.h:717
+
+      if (getTLI()->isExtFree(I))
+        return 0;
----------------
dmgreen wrote:
> I don't believe this will be correct from the vectorizer. It can pass a context instruction that has different types to the final IR due to it truncating at the same time it vectorizes. It is generally unsound to rely on I being accurate.
I'm sure there's going to be many cases like that, and the vectorizer can always choose to not pass the instruction.


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  https://reviews.llvm.org/D78922/new/

https://reviews.llvm.org/D78922