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

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-x86

Author: None (Temperz87)

<details>
<summary>Changes</summary>

This pr aims to resolve #<!-- -->152144 
In SelectionDAG::canCreateUndefOrPoison the ISD::SCMP/UCMP cases are added to always return false as they cannot generate poison or undef
The `freeze-binary.ll` file is now testing the SCMP/UCMP cases

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


2 Files Affected:

- (modified) llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp (+2) 
- (modified) llvm/test/CodeGen/X86/freeze-binary.ll (+72-1) 


``````````diff
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 84282d8a1c37b..cbbf885115a59 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -5748,6 +5748,8 @@ bool SelectionDAG::canCreateUndefOrPoison(SDValue Op, const APInt &DemandedElts,
   case ISD::FMA:
   case ISD::FMAD:
   case ISD::FP_EXTEND:
+  case ISD::SCMP:
+  case ISD::UCMP:
     // No poison except from flags (which is handled above)
     return false;
 
diff --git a/llvm/test/CodeGen/X86/freeze-binary.ll b/llvm/test/CodeGen/X86/freeze-binary.ll
index 962ffe47d0d51..af5b26f6e2dd9 100644
--- a/llvm/test/CodeGen/X86/freeze-binary.ll
+++ b/llvm/test/CodeGen/X86/freeze-binary.ll
@@ -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)
+  ret i32 %z
+}
+
+define i32 @freeze_ucmp(i32 %a0) nounwind {
+; X86-LABEL: freeze_ucmp:
+; X86:       # %bb.0:
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    cmpl $3, %eax
+; X86-NEXT:    setae %cl
+; X86-NEXT:    cmpl $2, %eax
+; X86-NEXT:    sbbb $0, %cl
+; X86-NEXT:    movsbl %cl, %eax
+; X86-NEXT:    cmpl $3, %eax
+; X86-NEXT:    setae %cl
+; X86-NEXT:    cmpl $2, %eax
+; X86-NEXT:    sbbb $0, %cl
+; X86-NEXT:    movsbl %cl, %eax
+; X86-NEXT:    retl
+;
+; X64-LABEL: freeze_ucmp:
+; X64:       # %bb.0:
+; X64-NEXT:    cmpl $3, %edi
+; X64-NEXT:    setae %al
+; X64-NEXT:    cmpl $2, %edi
+; X64-NEXT:    sbbb $0, %al
+; X64-NEXT:    movsbl %al, %eax
+; X64-NEXT:    cmpl $3, %eax
+; X64-NEXT:    setae %cl
+; X64-NEXT:    cmpl $2, %eax
+; X64-NEXT:    sbbb $0, %cl
+; X64-NEXT:    movsbl %cl, %eax
+; X64-NEXT:    retq
+  %x = call i32 @llvm.ucmp.i32(i32 %a0, i32 2)
+  %y = freeze i32 %x
+  %z = call i32 @llvm.ucmp.i32(i32 %y, i32 2)
+  ret i32 %z
+}
+
 define void @pr59676_frozen(ptr %dst, i32 %x.orig) {
 ; X86-LABEL: pr59676_frozen:
 ; X86:       # %bb.0:
@@ -1036,4 +1107,4 @@ define void @pr59676_nsw(ptr %dst, i32 %x) {
   %div = sdiv i32 %area, 42
   store i32 %div, ptr %dst, align 4
   ret void
-}
+}
\ No newline at end of file

``````````

</details>


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