[InstCombine] don't change the size of a select if it would mismatch its condition operands' sizes
Don't always:
cast (select (cmp x, y), z, C) --> select (cmp x, y), (cast z), C'
This is something that came up as far back as D26556, and I lost track of it.
I suspect that this transform is part of the underlying problem that is
inspiring some of the recent proposals that seek to match larger patterns
that include a cast op. Even if that's not true, this transform causes
problems for codegen (particularly with vector types).
A transform to actively match the size of cmp and select operand sizes should
follow. This patch just removes the harmful canonicalization in the other
direction.
Differential Revision: https://reviews.llvm.org/D47163
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@333611 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed