[llvm] [SeparateConstOffsetFromGEP] Support GEP reordering for different types (PR #90802)

[Nikita Popov via llvm-commits]

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@@ -972,22 +972,23 @@ SeparateConstOffsetFromGEP::lowerToArithmetics(GetElementPtrInst *Variadic,
 
 bool SeparateConstOffsetFromGEP::reorderGEP(GetElementPtrInst *GEP,
                                             TargetTransformInfo &TTI) {
-  Type *GEPType = GEP->getResultElementType();
+  Type *GEPType = GEP->getSourceElementType();
   // TODO: support reordering for non-trivial GEP chains
   if (GEPType->isAggregateType() || GEP->getNumIndices() != 1)
     return false;
 
   auto PtrGEP = dyn_cast<GetElementPtrInst>(GEP->getPointerOperand());
   if (!PtrGEP)
     return false;
-  Type *PtrGEPType = PtrGEP->getResultElementType();
+  Type *PtrGEPType = PtrGEP->getSourceElementType();
   // TODO: support reordering for non-trivial GEP chains
   if (PtrGEPType->isAggregateType() || PtrGEP->getNumIndices() != 1)
     return false;
 
-  // TODO: support reordering for non-trivial GEP chains
-  if (PtrGEPType != GEPType ||
-      PtrGEP->getSourceElementType() != GEP->getSourceElementType())
+  bool GEPIsPtr = GEPType->getScalarType()->isPtrOrPtrVectorTy();
+  bool PtrGEPIsPtr = PtrGEPType->getScalarType()->isPtrOrPtrVectorTy();
+
+  if (GEPIsPtr != PtrGEPIsPtr)
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nikic wrote:

What's the point of this check? Why do we care that the source element type is a pointer or vector of pointers?

https://github.com/llvm/llvm-project/pull/90802