[llvm-branch-commits] [llvm] InstCombine: Handle fsub in SimplifyDemandedFPClass (PR #175852)

[Yingwei Zheng via llvm-branch-commits]

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@@ -2157,11 +2162,13 @@ Value *InstCombinerImpl::SimplifyDemandedUseFPClass(Instruction *I,
     }
 
     // With nnan: X + {+/-}Inf --> {+/-}Inf
-    if (KnownRHS.isKnownAlways(fcInf | fcNan) &&
-        KnownLHS.isKnownNever(fcNan))
+    if (I->getOpcode() == Instruction::FAdd &&
+        KnownRHS.isKnownAlways(fcInf | fcNan) && KnownLHS.isKnownNever(fcNan)) {
       return I->getOperand(1);
+    }
 
     // With nnan: {+/-}Inf + X --> {+/-}Inf
+    // With nnan: {+/-}Inf - X --> {+/-}Inf
     if (KnownLHS.isKnownAlways(fcInf | fcNan) &&
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dtcxzyw wrote:

ResultNotNan && 

https://github.com/llvm/llvm-project/pull/175852