[PATCH] D63318: [DAGCombine] Teach DAGCombine to fold the aext + select pattern

[Craig Topper via Phabricator via llvm-commits]

craig.topper added a comment.

X86 looks ok to me other than i8->i64 zext problem.



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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
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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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