[llvm] [Transform] Treat umul + extract pattern as cheap single instruction. (PR #124933)

[Gábor Spaits via llvm-commits]

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@@ -3290,9 +3290,11 @@ bool SimplifyCFGOpt::speculativelyExecuteBB(BranchInst *BI,
   bool HoistLoadsStores = HoistLoadsStoresWithCondFaulting &&
                           Options.HoistLoadsStoresWithCondFaulting;
   SmallVector<Instruction *, 2> SpeculatedConditionalLoadsStores;
+  InstructionCost BlockCostSoFar = 0;
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spaits wrote:

I have introduced this block cost counter for later cases, when we are able to spec. execute more than one instructions. (Does anyone know, why we are limited to one instruction here? If I have some time I may check the git logs more and will try to found out.)

https://github.com/llvm/llvm-project/pull/124933