[llvm] [InstCombine] Missed fold: umax(x, C) > ~x -> x < 0 (PR #189396)

[Yingwei Zheng via llvm-commits]

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@@ -7785,13 +7785,35 @@ Instruction *InstCombinerImpl::visitICmpInst(ICmpInst &I) {
   if (Instruction *Res = foldICmpWithZero(I))
     return Res;
 
+  Value *X;
+  const APInt *C;
+  if (I.getPredicate() == ICmpInst::ICMP_UGT &&
+      match(Op0, m_UMax(m_Value(X), m_APInt(C))) &&
+      match(Op1, m_Not(m_Specific(X)))) {
+    if (C->isNonNegative())
+      return new ICmpInst(ICmpInst::ICMP_SLT, X,
+                          Constant::getNullValue(X->getType()));
+    return new ICmpInst(ICmpInst::ICMP_UGT, X,
+                        ConstantInt::get(X->getType(), ~*C));
+  }
+
+  if (I.getPredicate() == ICmpInst::ICMP_ULT &&
+      match(Op0, m_UMax(m_Value(X), m_APInt(C))) &&
+      match(Op1, m_Not(m_Specific(X)))) {
+    if (C->isNonNegative()) {
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dtcxzyw wrote:

Drop braces.

https://github.com/llvm/llvm-project/pull/189396