[PATCH] D97155: [MSSA] Extending IsGuaranteedLoopInvariant to support an instruction defined in the entry block

[Matteo Favaro via Phabricator via llvm-commits]

fvrmatteo created this revision.
fvrmatteo added a reviewer: fhahn.
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As mentioned in D96979 <https://reviews.llvm.org/D96979>, I'm extending the **IsGuaranteedLoopInvariant** check also to the `MemorySSA.cpp` file.

@fhahn For now I didn't unify the function into `MemorySSA.h` because, as you mentioned, it's not directly MSSA related. I'm open to suggestions to find a better place so we can improve the unification process.

I was also wondering if it would make sense to have a utility function called **isEntryBlockInstruction** (part of llvm::Instruction) to avoid the ugly check used in this (and the mentioned) patch.

I didn't provide a test yet, because it's not clear to me how to create one that is showing the improvement in the MemorySSA case.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D97155

Files:
  llvm/lib/Analysis/MemorySSA.cpp


Index: llvm/lib/Analysis/MemorySSA.cpp
===================================================================
--- llvm/lib/Analysis/MemorySSA.cpp
+++ llvm/lib/Analysis/MemorySSA.cpp
@@ -2551,6 +2551,11 @@
   };
 
   Ptr = Ptr->stripPointerCasts();
+  if (auto *I = dyn_cast<Instruction>(Ptr)) {
+    if (I->getParent() == &I->getFunction()->getEntryBlock()) {
+      return true;
+    }
+  }
   if (auto *GEP = dyn_cast<GEPOperator>(Ptr)) {
     return IsGuaranteedLoopInvariantBase(GEP->getPointerOperand()) &&
            GEP->hasAllConstantIndices();


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