[PATCH] D56214: AggressiveInstCombine: Fold full mul i64 x i64 -> i128

[Craig Topper via Phabricator via llvm-commits]

craig.topper added a comment.

This also does nothing to guarantee that all(or most) of the instructions will be removed. They could have additional users.

If we're in 32-bit mode then the 128-bit result producing X86 instruction doesn't exist. So this will get expanded to a bunch of smaller multiplies and adds. Do we produce something as good as or better than what we would get if we left the user code alone?


Repository:
  rL LLVM

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  https://reviews.llvm.org/D56214/new/

https://reviews.llvm.org/D56214