[llvm] [SimplifyCFG] Remove conservative fcmp guard from speculativelyExecuteBB (PR #211611)

[Guy David via llvm-commits]

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@@ -3454,7 +3450,10 @@ bool SimplifyCFGOpt::speculativelyExecuteBB(CondBrInst *BI,
     Value *TrueV = ThenV, *FalseV = OrigV;
     if (Invert)
       std::swap(TrueV, FalseV);
-    Value *V = Builder.CreateSelect(BrCond, TrueV, FalseV, "spec.select", BI);
+    // Propagate fast-math flags from the phi node to the replacement select.
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guy-david wrote:

Without propagation, several existing tests are regressing (speculate-math.ll) which makes it seem larger than it is.

https://github.com/llvm/llvm-project/pull/211611