[PATCH] D145299: [X86] Generate better code for std::bit_ceil

[Sanjay Patel via Phabricator via llvm-commits]

spatel added a comment.

In D145299#4169702 <https://reviews.llvm.org/D145299#4169702>, @RKSimon wrote:

> What is preventing is from performing this in InstCombine? I don't think this pattern will emerge in SelectionDAG

I haven't found a way to avoid a poison shift in IR without doing a cmp+select or umax yet. I think we're relying on the x86-specific behavior of masking the shift amount to make that part of the logic disappear in this patch.


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https://reviews.llvm.org/D145299