[llvm] [InstCombine] Add missing patterns for scmp and ucmp (PR #149225)

[Yingwei Zheng via llvm-commits]

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@@ -3849,6 +3853,45 @@ Instruction *InstCombinerImpl::foldSelectToCmp(SelectInst &SI) {
     }
   }
 
+  // Special cases with constants: x == C ? 0 : (x > C-1 ? 1 : -1)
+  if (Pred == ICmpInst::ICMP_EQ && match(TV, m_Zero())) {
+    Value *X;
+    const APInt *C;
+    if (match(RHS, m_APInt(C))) {
+      CmpPredicate InnerPred;
+      Value *InnerLHS, *InnerRHS;
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dtcxzyw wrote:

InnerLHS is unused.

https://github.com/llvm/llvm-project/pull/149225