[llvm] [InstCombine] Fold fcmp ogt (x - y), 0 into fcmp ogt x, y #85245 (PR #85506)

[via llvm-commits]

================
@@ -8037,6 +8037,44 @@ Instruction *InstCombinerImpl::visitFCmpInst(FCmpInst &I) {
       if (Instruction *NV = FoldOpIntoSelect(I, cast<SelectInst>(LHSI)))
         return NV;
       break;
+    case Instruction::FSub:
+      switch (Pred) {
+      default:
+        break;
+      case FCmpInst::FCMP_UGT:
+      case FCmpInst::FCMP_ULT:
+      case FCmpInst::FCMP_UNE:
+      case FCmpInst::FCMP_OEQ:
+      case FCmpInst::FCMP_OGE:
+      case FCmpInst::FCMP_OLE:
+        // fsub x, y --> isnnan(x, y) && isninf(x, y)
----------------
SahilPatidar wrote:

I apologize for my poor commenting skills.

https://github.com/llvm/llvm-project/pull/85506