[PATCH] D63318: [DAGCombine] Teach DAGCombine to fold the aext + select pattern
Craig Topper via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Tue Jun 18 23:25:43 PDT 2019
craig.topper added a comment.
X86 looks ok to me other than i8->i64 zext problem.
================
Comment at: llvm/test/CodeGen/X86/cmov-promotion.ll:59
; CMOV-NEXT: movl $255, %eax
-; CMOV-NEXT: cmovnel %ecx, %eax
+; CMOV-NEXT: cmovneq %rcx, %rax
; CMOV-NEXT: retq
----------------
The zextisfree check isn't enough to fix this :( It's an i8->i64 zext which isn't free. I guess we'll have to handle this in the x86 backend.
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https://reviews.llvm.org/D63318/new/
https://reviews.llvm.org/D63318
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