[llvm] [ReachingDefAnalysis] Extend the analysis to stack objects. (PR #118097)

[Michael Maitland via llvm-commits]

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@@ -269,6 +341,19 @@ int ReachingDefAnalysis::getReachingDef(MachineInstr *MI,
   assert(MBBNumber < MBBReachingDefs.numBlockIDs() &&
          "Unexpected basic block number.");
   int LatestDef = ReachingDefDefaultVal;
+
+  if (Register::isStackSlot(Reg)) {
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michaelmaitland wrote:

But MCRegister has the [isStackSlot function](https://llvm.org/doxygen/classllvm_1_1MCRegister.html#a01c52fcd65bb831db823ecd35cf0a3ba) which suggests that it can be storing a stack slot? 

https://github.com/llvm/llvm-project/pull/118097