[llvm] [GlobalIsel] Combine select to integer minmax (second attemnt). (PR #77520)

[Thorsten Schütt via llvm-commits]

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@@ -6548,6 +6548,87 @@ bool CombinerHelper::tryFoldBoolSelectToLogic(GSelect *Select,
   return false;
 }
 
+bool CombinerHelper::tryFoldSelectToIntMinMax(GSelect *Select,
+                                              BuildFnTy &MatchInfo) {
+  Register DstReg = Select->getReg(0);
+  Register Cond = Select->getCondReg();
+  Register True = Select->getTrueReg();
+  Register False = Select->getFalseReg();
+  LLT DstTy = MRI.getType(DstReg);
+
+  // We need an G_ICMP on the condition register.
+  GICmp *Cmp = getOpcodeDef<GICmp>(Cond, MRI);
+  if (!Cmp)
+    return false;
+
+  // We want to fold the icmp and replace the select.
+  if (!MRI.hasOneNonDBGUse(Cmp->getReg(0)))
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tschuett wrote:

one use one icmp.

https://github.com/llvm/llvm-project/pull/77520