[llvm] [DAG] SelectionDAG::canCreateUndefOrPoison - add ISD::SCMP/UCMP handling + tests (PR #154127)

[via llvm-commits]

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@@ -924,6 +924,77 @@ define i32 @freeze_usubo(i32 %a0, i32 %a1, i8 %a2, i8 %a3) nounwind {
   ret i32 %r
 }
 
+
+define i32 @freeze_scmp(i32 %a0) nounwind {
+; X86-LABEL: freeze_scmp:
+; X86:       # %bb.0:
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    cmpl $2, %eax
+; X86-NEXT:    setl %al
+; X86-NEXT:    setg %cl
+; X86-NEXT:    subb %al, %cl
+; X86-NEXT:    movsbl %cl, %eax
+; X86-NEXT:    cmpl $2, %eax
+; X86-NEXT:    setl %al
+; X86-NEXT:    setg %cl
+; X86-NEXT:    subb %al, %cl
+; X86-NEXT:    movsbl %cl, %eax
+; X86-NEXT:    retl
+;
+; X64-LABEL: freeze_scmp:
+; X64:       # %bb.0:
+; X64-NEXT:    cmpl $2, %edi
+; X64-NEXT:    setl %al
+; X64-NEXT:    setg %cl
+; X64-NEXT:    subb %al, %cl
+; X64-NEXT:    movsbl %cl, %eax
+; X64-NEXT:    cmpl $2, %eax
+; X64-NEXT:    setl %al
+; X64-NEXT:    setg %cl
+; X64-NEXT:    subb %al, %cl
+; X64-NEXT:    movsbl %cl, %eax
+; X64-NEXT:    retq
+  %x = call i32 @llvm.scmp.i32(i32 %a0, i32 2)
+  %y = freeze i32 %x
+  %z = call i32 @llvm.scmp.i32(i32 %y, i32 2)
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Temperz87 wrote:

I think so? The local tests are passing and I don't see why it shouldn't be working

https://github.com/llvm/llvm-project/pull/154127