[opaque pointer type] Pass explicit pointer type through GEP constant folding

llvm-svn: 236670

3 files changed, 34 insertions, 12 deletions

diff --git a/llvm/lib/IR/ConstantFold.cpp b/llvm/lib/IR/ConstantFold.cpp
index 2a524937391..8afb3e489de 100644
--- a/llvm/lib/IR/ConstantFold.cpp
+++ b/llvm/lib/IR/ConstantFold.cpp
@@ -2028,7 +2028,7 @@ static bool isIndexInRangeOfSequentialType(const SequentialType *STy,
 }
 
 template<typename IndexTy>
-static Constant *ConstantFoldGetElementPtrImpl(Constant *C,
+static Constant *ConstantFoldGetElementPtrImpl(Type *PointeeTy, Constant *C,
                                                bool inBounds,
                                                ArrayRef<IndexTy> Idxs) {
   if (Idxs.empty()) return C;
@@ -2165,9 +2165,9 @@ static Constant *ConstantFoldGetElementPtrImpl(Constant *C,
   // factored out into preceding dimensions.
   bool Unknown = false;
   SmallVector<Constant *, 8> NewIdxs;
-  Type *Ty = C->getType();
-  Type *Prev = nullptr;
-  for (unsigned i = 0, e = Idxs.size(); i != e;
+  Type *Ty = PointeeTy;
+  Type *Prev = C->getType();
+  for (unsigned i = 1, e = Idxs.size(); i != e;
        Prev = Ty, Ty = cast<CompositeType>(Ty)->getTypeAtIndex(Idxs[i]), ++i) {
     if (ConstantInt *CI = dyn_cast<ConstantInt>(Idxs[i])) {
       if (isa<ArrayType>(Ty) || isa<VectorType>(Ty))
@@ -2229,7 +2229,7 @@ static Constant *ConstantFoldGetElementPtrImpl(Constant *C,
   if (!Unknown && !inBounds)
     if (auto *GV = dyn_cast<GlobalVariable>(C))
       if (!GV->hasExternalWeakLinkage() && isInBoundsIndices(Idxs))
-        return ConstantExpr::getInBoundsGetElementPtr(nullptr, C, Idxs);
+        return ConstantExpr::getInBoundsGetElementPtr(PointeeTy, C, Idxs);
 
   return nullptr;
 }
@@ -2237,11 +2237,27 @@ static Constant *ConstantFoldGetElementPtrImpl(Constant *C,
 Constant *llvm::ConstantFoldGetElementPtr(Constant *C,
                                           bool inBounds,
                                           ArrayRef<Constant *> Idxs) {
-  return ConstantFoldGetElementPtrImpl(C, inBounds, Idxs);
+  return ConstantFoldGetElementPtrImpl(
+      cast<PointerType>(C->getType()->getScalarType())->getElementType(), C,
+      inBounds, Idxs);
 }
 
 Constant *llvm::ConstantFoldGetElementPtr(Constant *C,
                                           bool inBounds,
                                           ArrayRef<Value *> Idxs) {
-  return ConstantFoldGetElementPtrImpl(C, inBounds, Idxs);
+  return ConstantFoldGetElementPtrImpl(
+      cast<PointerType>(C->getType()->getScalarType())->getElementType(), C,
+      inBounds, Idxs);
+}
+
+Constant *llvm::ConstantFoldGetElementPtr(Type *Ty, Constant *C,
+                                          bool inBounds,
+                                          ArrayRef<Constant *> Idxs) {
+  return ConstantFoldGetElementPtrImpl(Ty, C, inBounds, Idxs);
+}
+
+Constant *llvm::ConstantFoldGetElementPtr(Type *Ty, Constant *C,
+                                          bool inBounds,
+                                          ArrayRef<Value *> Idxs) {
+  return ConstantFoldGetElementPtrImpl(Ty, C, inBounds, Idxs);
 }
diff --git a/llvm/lib/IR/ConstantFold.h b/llvm/lib/IR/ConstantFold.h
index a516abe024e..42a9c6ba908 100644
--- a/llvm/lib/IR/ConstantFold.h
+++ b/llvm/lib/IR/ConstantFold.h
@@ -51,6 +51,10 @@ namespace llvm {
                                       ArrayRef<Constant *> Idxs);
   Constant *ConstantFoldGetElementPtr(Constant *C, bool inBounds,
                                       ArrayRef<Value *> Idxs);
+  Constant *ConstantFoldGetElementPtr(Type *Ty, Constant *C, bool inBounds,
+                                      ArrayRef<Constant *> Idxs);
+  Constant *ConstantFoldGetElementPtr(Type *Ty, Constant *C, bool inBounds,
+                                      ArrayRef<Value *> Idxs);
 } // End llvm namespace
 
 #endif
diff --git a/llvm/lib/IR/Constants.cpp b/llvm/lib/IR/Constants.cpp
index 20a5206c230..b598c2807ce 100644
--- a/llvm/lib/IR/Constants.cpp
+++ b/llvm/lib/IR/Constants.cpp
@@ -2015,14 +2015,16 @@ Constant *ConstantExpr::getSelect(Constant *C, Constant *V1, Constant *V2,
 Constant *ConstantExpr::getGetElementPtr(Type *Ty, Constant *C,
                                          ArrayRef<Value *> Idxs, bool InBounds,
                                          Type *OnlyIfReducedTy) {
-  if (Constant *FC = ConstantFoldGetElementPtr(C, InBounds, Idxs))
-    return FC;          // Fold a few common cases.
-
   if (!Ty)
     Ty = cast<PointerType>(C->getType()->getScalarType())->getElementType();
   else
-    assert(Ty ==
-           cast<PointerType>(C->getType()->getScalarType())->getElementType());
+    assert(
+        Ty ==
+        cast<PointerType>(C->getType()->getScalarType())->getContainedType(0u));
+
+  if (Constant *FC = ConstantFoldGetElementPtr(Ty, C, InBounds, Idxs))
+    return FC;          // Fold a few common cases.
+
   // Get the result type of the getelementptr!
   Type *DestTy = GetElementPtrInst::getIndexedType(Ty, Idxs);
   assert(DestTy && "GEP indices invalid!");