[llvm] [GlobalISel] Fold G_ICMP if possible (PR #86357)

[Shilei Tian via llvm-commits]

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@@ -7673,12 +7680,16 @@ LegalizerHelper::lowerSADDO_SSUBO(MachineInstr &MI) {
   // (LHS) if and only if the other operand (RHS) is (non-zero) positive,
   // otherwise there will be overflow.
   auto ResultLowerThanLHS =
-      MIRBuilder.buildICmp(CmpInst::ICMP_SLT, BoolTy, Dst0, LHS);
+      MIRBuilder.buildICmp(CmpInst::ICMP_SLT, BoolTy, NewDst0, LHS);
   auto ConditionRHS = MIRBuilder.buildICmp(
       IsAdd ? CmpInst::ICMP_SLT : CmpInst::ICMP_SGT, BoolTy, RHS, Zero);
 
-  MIRBuilder.buildXor(Dst1, ConditionRHS, ResultLowerThanLHS);
+  MIRBuilder.buildXor(NewDst1, ConditionRHS, ResultLowerThanLHS);
+
+  MIRBuilder.buildCopy(Dst0, NewDst0);
+  MIRBuilder.buildCopy(Dst1, NewDst1);
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shiltian wrote:

Yes

https://github.com/llvm/llvm-project/pull/86357