[PATCH] D15618: [NaryReassociate] allow candidate to have a different type

[Jingyue Wu via llvm-commits]

jingyue created this revision.
jingyue added a reviewer: meheff.
jingyue added a subscriber: llvm-commits.
Herald added a subscriber: jholewinski.

If Candiadte may have a different type from GEP, we should bitcast or
pointer cast it to GEP's type so that the later RAUW doesn't complain.

Added a test in nary-gep.ll

http://reviews.llvm.org/D15618

Files:
  lib/Transforms/Scalar/NaryReassociate.cpp
  test/Transforms/NaryReassociate/NVPTX/nary-gep.ll

Index: test/Transforms/NaryReassociate/NVPTX/nary-gep.ll
===================================================================
--- test/Transforms/NaryReassociate/NVPTX/nary-gep.ll
+++ test/Transforms/NaryReassociate/NVPTX/nary-gep.ll
@@ -123,4 +123,21 @@
   ret void
 }
 
+%struct.complex = type { float, float }
+
+declare void @bar(%struct.complex*)
+
+define void @different_types(%struct.complex* %input, i64 %i) {
+; CHECK-LABEL: @different_types(
+  %t1 = getelementptr %struct.complex, %struct.complex* %input, i64 %i
+  call void @bar(%struct.complex* %t1)
+  %j = add i64 %i, 5
+  %t2 = getelementptr %struct.complex, %struct.complex* %input, i64 %j, i32 0
+; CHECK: [[cast:[^ ]+]] = bitcast %struct.complex* %t1 to float*
+; CHECK-NEXT: %t2 = getelementptr float, float* [[cast]], i64 10
+; CHECK-NEXT: call void @foo(float* %t2)
+  call void @foo(float* %t2)
+  ret void
+}
+
 declare void @llvm.assume(i1)
Index: lib/Transforms/Scalar/NaryReassociate.cpp
===================================================================
--- lib/Transforms/Scalar/NaryReassociate.cpp
+++ lib/Transforms/Scalar/NaryReassociate.cpp
@@ -421,19 +421,20 @@
       GEP->getSourceElementType(), SE->getSCEV(GEP->getPointerOperand()),
       IndexExprs, GEP->isInBounds());
 
-  auto *Candidate = findClosestMatchingDominator(CandidateExpr, GEP);
+  Value *Candidate = findClosestMatchingDominator(CandidateExpr, GEP);
   if (Candidate == nullptr)
     return nullptr;
 
-  PointerType *TypeOfCandidate = dyn_cast<PointerType>(Candidate->getType());
-  // Pretty rare but theoretically possible when a numeric value happens to
-  // share CandidateExpr.
-  if (TypeOfCandidate == nullptr)
-    return nullptr;
+  IRBuilder<> Builder(GEP);
+  // Candidate does not necessarily have the same pointer type as GEP. Use
+  // bitcast or pointer cast to make sure they have the same type, so that the
+  // later RAUW doesn't complain.
+  Candidate = Builder.CreateBitOrPointerCast(Candidate, GEP->getType());
+  assert(Candidate->getType() == GEP->getType());
 
   // NewGEP = (char *)Candidate + RHS * sizeof(IndexedType)
   uint64_t IndexedSize = DL->getTypeAllocSize(IndexedType);
-  Type *ElementType = TypeOfCandidate->getElementType();
+  Type *ElementType = GEP->getType()->getElementType();
   uint64_t ElementSize = DL->getTypeAllocSize(ElementType);
   // Another less rare case: because I is not necessarily the last index of the
   // GEP, the size of the type at the I-th index (IndexedSize) is not
@@ -453,8 +454,7 @@
     return nullptr;
 
   // NewGEP = &Candidate[RHS * (sizeof(IndexedType) / sizeof(Candidate[0])));
-  IRBuilder<> Builder(GEP);
-  Type *IntPtrTy = DL->getIntPtrType(TypeOfCandidate);
+  Type *IntPtrTy = DL->getIntPtrType(GEP->getType());
   if (RHS->getType() != IntPtrTy)
     RHS = Builder.CreateSExtOrTrunc(RHS, IntPtrTy);
   if (IndexedSize != ElementSize) {


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