[SROA] Use offset sizes from the DataLayout instead of the pointer siezes.

[Nicola]

Summary

This fixes an assertion when constant folding a GEP when the part of the offset was in i32 (IndexSize, as per DataLayout) and part in the i64 (PointerSize) in the newly created test case.

[efriedma]

Please use FileCheck to check that the output is actually what you expect, in addition to not crashing.

[delena]

I'm ok with the code itself. I agree with Eli that you should add CHECKs.

[Nicola]

Changed the test to return a value and keep alive the interesting GEP

lib/Transforms/Scalar/SROA.cpp

 /// indicated by Indices to have the correct offset.
 static Value *getNaturalGEPWithType(IRBuilderTy &IRB, const DataLayout &DL,
                                     Value *BasePtr, Type *Ty, Type *TargetTy,
                                     SmallVectorImpl<Value *> &Indices,
                                     Twine NamePrefix) {
   if (Ty == TargetTy)
     return buildGEP(IRB, BasePtr, Indices, NamePrefix);
 
-  // Pointer size to use for the indices.
-  unsigned PtrSize = DL.getPointerTypeSizeInBits(BasePtr->getType());
+  // Offset size to use for the indices.
+  unsigned OffsetSize = DL.getIndexTypeSizeInBits(BasePtr->getType());
 
   // See if we can descend into a struct and locate a field with the correct
   // type.
   unsigned NumLayers = 0;
   Type *ElementTy = Ty;
   do {
     if (ElementTy->isPointerTy())
       break;
 
     if (ArrayType *ArrayTy = dyn_cast<ArrayType>(ElementTy)) {
       ElementTy = ArrayTy->getElementType();
-      Indices.push_back(IRB.getIntN(PtrSize, 0));
+      Indices.push_back(IRB.getIntN(OffsetSize, 0));
     } else if (VectorType *VectorTy = dyn_cast<VectorType>(ElementTy)) {
       ElementTy = VectorTy->getElementType();
       Indices.push_back(IRB.getInt32(0));
     } else if (StructType *STy = dyn_cast<StructType>(ElementTy)) {
       if (STy->element_begin() == STy->element_end())
         break; // Nothing left to descend into.
       ElementTy = *STy->element_begin();
       Indices.push_back(IRB.getInt32(0));
if (LastSROAPrefix != StringRef::npos) {
           OldName = OldName.substr(OffsetEnd + 1);
       }
     }
     // Strip any SROA suffixes as well.
     OldName = OldName.substr(0, OldName.find(".sroa_"));
 #endif
 
     return getAdjustedPtr(IRB, DL, &NewAI,
-                          APInt(DL.getPointerTypeSizeInBits(PointerTy), Offset),
+                          APInt(DL.getIndexTypeSizeInBits(PointerTy), Offset),
                           PointerTy,
 #ifndef NDEBUG
                           Twine(OldName) + "."
 #else
                           Twine()
 #endif
                           );
   }
if (AllocaInst *AI =
              "Splittable transfers cannot reach the same alloca on both ends.");
       Pass.Worklist.insert(AI);
     }
 
     Type *OtherPtrTy = OtherPtr->getType();
     unsigned OtherAS = OtherPtrTy->getPointerAddressSpace();
 
     // Compute the relative offset for the other pointer within the transfer.
-    unsigned IntPtrWidth = DL.getPointerSizeInBits(OtherAS);
-    APInt OtherOffset(IntPtrWidth, NewBeginOffset - BeginOffset);
+    unsigned OffsetWidth = DL.getIndexSizeInBits(OtherAS);
+    APInt OtherOffset(OffsetWidth, NewBeginOffset - BeginOffset);
     unsigned OtherAlign =
       IsDest ? II.getSourceAlignment() : II.getDestAlignment();
     OtherAlign =  MinAlign(OtherAlign ? OtherAlign : 1,
                            OtherOffset.zextOrTrunc(64).getZExtValue());
 
     if (EmitMemCpy) {
       // Compute the other pointer, folding as much as possible to produce
       // a single, simple GEP in most cases.

test/Transforms/SROA/pointer-offset-size.ll

+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -sroa -S | FileCheck %s
+target datalayout = "e-p:64:64:64:32"
+
+%struct.test = type { %struct.basic, %struct.basic }
+%struct.basic = type { i16, i8 }
+
+define i16 @test(%struct.test* %ts2.i) {
+; CHECK-LABEL: @test(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[S_SROA_0:%.*]] = alloca [3 x i8], align 2
+; CHECK-NEXT:    [[S_SROA_0_0__SROA_CAST:%.*]] = bitcast %struct.test* [[TS2_I:%.*]] to i8*
+; CHECK-NEXT:    [[S_SROA_0_0__SROA_IDX:%.*]] = getelementptr inbounds [3 x i8], [3 x i8]* [[S_SROA_0]], i32 0, i32 0
+; CHECK-NEXT:    call void @llvm.memcpy.p0i8.p0i8.i32(i8* align 1 [[S_SROA_0_0__SROA_CAST]], i8* align 2 [[S_SROA_0_0__SROA_IDX]], i32 3, i1 false)
+; CHECK-NEXT:    [[X1_I_I:%.*]] = getelementptr inbounds [[STRUCT_TEST:%.*]], %struct.test* [[TS2_I]], i32 0, i32 0, i32 0
+; CHECK-NEXT:    [[TMP0:%.*]] = load i16, i16* [[X1_I_I]]
+; CHECK-NEXT:    ret i16 [[TMP0]]
+;
+entry:
+  %s = alloca %struct.test
+  %0 = bitcast %struct.test* %ts2.i to i8*
+  %1 = bitcast %struct.test* %s to i8*
+  call void @llvm.memcpy.p0i8.p0i8.i32(i8* %0, i8* %1, i32 3, i1 false)
+  %x1.i.i = getelementptr inbounds %struct.test, %struct.test* %ts2.i, i32 0, i32 0, i32 0
+  %2 = load i16, i16* %x1.i.i
+  ret i16 %2
+}
+
+declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture writeonly, i8* nocapture readonly, i32, i1)