Use correct address space size GEP index in SROA

[chandlerc]

See below, only half of this change is necessary.

lib/Transforms/Scalar/SROA.cpp

2024–2026

This change is unnecessary, and doesn't make any sense. The alloca pointer is always in address space zero.

2432

We should test this by wrapping around the end of the address space if we want to be pedantic. Maybe not necessary.

[arsenm]

Split out removing default address space argument part, change test to modify one added by the other SROA patch

[chandlerc]

Looks good now that the basis is in place. Inspired a tweak to IRBuilder. I made that tweak and applied in r202252 to avoid you having to rebase, etc.

Thanks!

lib/Transforms/Scalar/SROA.cpp

   if (Ty == TargetTy)
     return buildGEP(IRB, BasePtr, Indices);
 
+  // Pointer size to use for the indices.
+  unsigned PtrSize = DL.getPointerTypeSizeInBits(BasePtr->getType());
+
   // See if we can descend into a struct and locate a field with the correct
   // type.
   unsigned NumLayers = 0;

   do {
     if (ElementTy->isPointerTy())
       break;
-    if (SequentialType *SeqTy = dyn_cast<SequentialType>(ElementTy)) {
-      ElementTy = SeqTy->getElementType();
-      // Note that we use the default address space as this index is over an
-      // array or a vector, not a pointer.
-      Indices.push_back(IRB.getInt(APInt(DL.getPointerSizeInBits(0), 0)));
+
+    if (ArrayType *ArrayTy = dyn_cast<ArrayType>(ElementTy)) {
+      ElementTy = ArrayTy->getElementType();
+      Indices.push_back(IRB.getInt(APInt(PtrSize, 0)));
+    } else if (VectorType *VectorTy = dyn_cast<VectorType>(ElementTy)) {
+      ElementTy = VectorTy->getElementType();
+      Indices.push_back(IRB.getInt(APInt(32, 0)));
     } else if (StructType *STy = dyn_cast<StructType>(ElementTy)) {
       if (STy->element_begin() == STy->element_end())
         break; // Nothing left to descend into.

test/Transforms/SROA/basictest.ll

 ; CHECK: alloca [16 x i8], align 8
 
   %gep = getelementptr inbounds { [16 x i8] } addrspace(1)* %ptr, i64 -1
-; CHECK-NEXT: getelementptr inbounds { [16 x i8] } addrspace(1)* %ptr, i16 -1, i32 0, i64 0
+; CHECK-NEXT: getelementptr inbounds { [16 x i8] } addrspace(1)* %ptr, i16 -1, i32 0, i16 0
 
   %cast1 = bitcast { [16 x i8 ] } addrspace(1)* %gep to i8 addrspace(1)*
   %cast2 = bitcast { [16 x i8 ] }* %a to i8*