[SelectionDAG] Use TypeSize for the stack offset.

[HsiangKai]

Summary

The return value type of getSizeInBits() is TypeSize now. Keep the type of the offset as TypeSize to enable concat_vectors to handle scalable vector objects correctly.

[paulwalker-arm]

Change looks sensible but please add a test.

[craig.topper]

llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp

1436–1438

Does this assert need to be updated so that it doesn't implicitly cast TypeByteSize to an unsigned? I assume that will print a warning about assuming fixed size.

[evandro]

LGTM

[paulwalker-arm]

As before I still believe there should be a test to protect this fix as presumably you're doing it for a reason.

[HsiangKai]

In D91834#2478933, @paulwalker-arm wrote:

As before I still believe there should be a test to protect this fix as presumably you're doing it for a reason.

I agree. I encountered the bug when implementing some vector instructions in the downstream. Currently, we are changing the way to implement these vector instructions. We could not trigger it any more under the new implementation. So, I have no idea how to create the test case now. I will not land this commit until I could find a way to test it.

llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp

SDValue SelectionDAGLegalize::ExpandVectorBuildThroughStack(SDNode* Node) {
   SDLoc dl(Node);
   SDValue FIPtr = DAG.CreateStackTemporary(VT);
   int FI = cast<FrameIndexSDNode>(FIPtr.getNode())->getIndex();
   MachinePointerInfo PtrInfo =
       MachinePointerInfo::getFixedStack(DAG.getMachineFunction(), FI);
 
   // Emit a store of each element to the stack slot.
   SmallVector<SDValue, 8> Stores;
-  unsigned TypeByteSize = MemVT.getSizeInBits() / 8;
-  assert(TypeByteSize > 0 && "Vector element type too small for stack store!");
+  TypeSize TypeByteSize = MemVT.getStoreSize();
+  assert(TypeByteSize.getKnownMinSize() > 0 &&
+         "Vector element type too small for stack store!");
 
   // If the destination vector element type of a BUILD_VECTOR is narrower than
   // the source element type, only store the bits necessary.
   bool Truncate = isa<BuildVectorSDNode>(Node) &&
                   MemVT.bitsLT(Node->getOperand(0).getValueType());
 
   // Store (in the right endianness) the elements to memory.
   for (unsigned i = 0, e = Node->getNumOperands(); i != e; ++i) {
     // Ignore undef elements.
     if (Node->getOperand(i).isUndef()) continue;
 
-    unsigned Offset = TypeByteSize*i;
+    TypeSize Offset = TypeByteSize * i;
 
-    SDValue Idx = DAG.getMemBasePlusOffset(FIPtr, TypeSize::Fixed(Offset), dl);
+    SDValue Idx = DAG.getMemBasePlusOffset(FIPtr, Offset, dl);
 
     if (Truncate)
       Stores.push_back(DAG.getTruncStore(DAG.getEntryNode(), dl,
                                          Node->getOperand(i), Idx,
                                          PtrInfo.getWithOffset(Offset), MemVT));
     else
       Stores.push_back(DAG.getStore(DAG.getEntryNode(), dl, Node->getOperand(i),
                                     Idx, PtrInfo.getWithOffset(Offset)));