[llvm] [FuncSpec] Query SCCPSolver in more places (PR #114964)

[Hari Limaye via llvm-commits]

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@@ -312,10 +317,10 @@ bool InstCostVisitor::discoverTransitivelyIncomingValues(
 
       // Disregard self-references and dead incoming values.
       if (auto *Inst = dyn_cast<Instruction>(V))
-        if (Inst == PN || DeadBlocks.contains(PN->getIncomingBlock(I)))
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hazzlim wrote:

It's maybe confusing that this function is named the same as the `SCCPSolver` member function, but this change is to make us dispatch to `InstCostVisitor::isBlockExecutable`, which checks both the `SCCPSolver` and DeadBlocks:
https://github.com/llvm/llvm-project/blob/2de3d00edc614cdce4b30b68be564a7a3123dbf9/llvm/include/llvm/Transforms/IPO/FunctionSpecialization.h#L179-L181

https://github.com/llvm/llvm-project/pull/114964