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

[Yingwei Zheng via llvm-branch-commits]

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@@ -279,6 +279,27 @@ KnownFPClass KnownFPClass::fadd_self(const KnownFPClass &KnownSrc,
   return Known;
 }
 
+KnownFPClass KnownFPClass::fsub(const KnownFPClass &KnownLHS,
+                                const KnownFPClass &KnownRHS,
+                                DenormalMode Mode) {
+  KnownFPClass Known;
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dtcxzyw wrote:

We can reinterpret fsub as fadd(LHS, fneg(RHS)).

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