1 files changed, 52 insertions, 3 deletions

diff --git a/clang/lib/CodeGen/CGExprScalar.cpp b/clang/lib/CodeGen/CGExprScalar.cpp
index e70c31ad63a..dc8186563ce 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -3407,6 +3407,52 @@ static Value *ConvertVec3AndVec4(CGBuilderTy &Builder, CodeGenFunction &CGF,
   return Builder.CreateShuffleVector(Src, UnV, Mask);
 }
 
+// Create cast instructions for converting LLVM value \p Src to LLVM type \p
+// DstTy. \p Src has the same size as \p DstTy. Both are single value types
+// but could be scalar or vectors of different lengths, and either can be
+// pointer.
+// There are 4 cases:
+// 1. non-pointer -> non-pointer  : needs 1 bitcast
+// 2. pointer -> pointer          : needs 1 bitcast or addrspacecast
+// 3. pointer -> non-pointer
+//   a) pointer -> intptr_t       : needs 1 ptrtoint
+//   b) pointer -> non-intptr_t   : needs 1 ptrtoint then 1 bitcast
+// 4. non-pointer -> pointer
+//   a) intptr_t -> pointer       : needs 1 inttoptr
+//   b) non-intptr_t -> pointer   : needs 1 bitcast then 1 inttoptr
+// Note: for cases 3b and 4b two casts are required since LLVM casts do not
+// allow casting directly between pointer types and non-integer non-pointer
+// types.
+static Value *createCastsForTypeOfSameSize(CGBuilderTy &Builder,
+                                           const llvm::DataLayout &DL,
+                                           Value *Src, llvm::Type *DstTy,
+                                           StringRef Name = "") {
+  auto SrcTy = Src->getType();
+
+  // Case 1.
+  if (!SrcTy->isPointerTy() && !DstTy->isPointerTy())
+    return Builder.CreateBitCast(Src, DstTy, Name);
+
+  // Case 2.
+  if (SrcTy->isPointerTy() && DstTy->isPointerTy())
+    return Builder.CreatePointerBitCastOrAddrSpaceCast(Src, DstTy, Name);
+
+  // Case 3.
+  if (SrcTy->isPointerTy() && !DstTy->isPointerTy()) {
+    // Case 3b.
+    if (!DstTy->isIntegerTy())
+      Src = Builder.CreatePtrToInt(Src, DL.getIntPtrType(SrcTy));
+    // Cases 3a and 3b.
+    return Builder.CreateBitOrPointerCast(Src, DstTy, Name);
+  }
+
+  // Case 4b.
+  if (!SrcTy->isIntegerTy())
+    Src = Builder.CreateBitCast(Src, DL.getIntPtrType(DstTy));
+  // Cases 4a and 4b.
+  return Builder.CreateIntToPtr(Src, DstTy, Name);
+}
+
 Value *ScalarExprEmitter::VisitAsTypeExpr(AsTypeExpr *E) {
   Value *Src  = CGF.EmitScalarExpr(E->getSrcExpr());
   llvm::Type *DstTy = ConvertType(E->getType());
@@ -3421,7 +3467,8 @@ Value *ScalarExprEmitter::VisitAsTypeExpr(AsTypeExpr *E) {
   // vector to get a vec4, then a bitcast if the target type is different.
   if (NumElementsSrc == 3 && NumElementsDst != 3) {
     Src = ConvertVec3AndVec4(Builder, CGF, Src, 4);
-    Src = Builder.CreateBitCast(Src, DstTy);
+    Src = createCastsForTypeOfSameSize(Builder, CGF.CGM.getDataLayout(), Src,
+                                       DstTy);
     Src->setName("astype");
     return Src;
   }
@@ -3431,13 +3478,15 @@ Value *ScalarExprEmitter::VisitAsTypeExpr(AsTypeExpr *E) {
   // get a vec3.
   if (NumElementsSrc != 3 && NumElementsDst == 3) {
     auto Vec4Ty = llvm::VectorType::get(DstTy->getVectorElementType(), 4);
-    Src = Builder.CreateBitCast(Src, Vec4Ty);
+    Src = createCastsForTypeOfSameSize(Builder, CGF.CGM.getDataLayout(), Src,
+                                       Vec4Ty);
     Src = ConvertVec3AndVec4(Builder, CGF, Src, 3);
     Src->setName("astype");
     return Src;
   }
 
-  return Builder.CreateBitCast(Src, DstTy, "astype");
+  return Src = createCastsForTypeOfSameSize(Builder, CGF.CGM.getDataLayout(),
+                                            Src, DstTy, "astype");
 }
 
 Value *ScalarExprEmitter::VisitAtomicExpr(AtomicExpr *E) {