[CodeGen] Make OrigTy in CC lowering the non-aggregate type (#153414)

https://github.com/llvm/llvm-project/pull/152709 exposed the original IR
argument type to the CC lowering logic. However, in SDAG, this used the
raw type, prior to aggregate splitting. This PR changes it to use the
non-aggregate type instead. (This matches what happened in the
GlobalISel case already.)

I've also added some more detailed documentation on the
InputArg/OutputArg fields, to explain how they differ. In most cases
ArgVT is going to be the EVT of OrigTy, so they encode very similar
information (OrigTy just preserves some additional information lost in
EVTs, like pointer types). One case where they do differ is in
post-legalization lowering of libcalls, where ArgVT is going to be a
legalized type, while OrigTy is going to be the original non-legalized
type.

1 files changed, 6 insertions, 6 deletions

diff --git a/llvm/lib/CodeGen/TargetLoweringBase.cpp b/llvm/lib/CodeGen/TargetLoweringBase.cpp
index 61ff2df..350948a 100644
--- a/llvm/lib/CodeGen/TargetLoweringBase.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringBase.cpp
@@ -1738,13 +1738,13 @@ void llvm::GetReturnInfo(CallingConv::ID CC, Type *ReturnType,
                          AttributeList attr,
                          SmallVectorImpl<ISD::OutputArg> &Outs,
                          const TargetLowering &TLI, const DataLayout &DL) {
-  SmallVector<EVT, 4> ValueVTs;
-  ComputeValueVTs(TLI, DL, ReturnType, ValueVTs);
-  unsigned NumValues = ValueVTs.size();
+  SmallVector<Type *, 4> Types;
+  ComputeValueTypes(DL, ReturnType, Types);
+  unsigned NumValues = Types.size();
   if (NumValues == 0) return;
 
-  for (unsigned j = 0, f = NumValues; j != f; ++j) {
-    EVT VT = ValueVTs[j];
+  for (Type *Ty : Types) {
+    EVT VT = TLI.getValueType(DL, Ty);
     ISD::NodeType ExtendKind = ISD::ANY_EXTEND;
 
     if (attr.hasRetAttr(Attribute::SExt))
@@ -1772,7 +1772,7 @@ void llvm::GetReturnInfo(CallingConv::ID CC, Type *ReturnType,
       Flags.setZExt();
 
     for (unsigned i = 0; i < NumParts; ++i)
-      Outs.push_back(ISD::OutputArg(Flags, PartVT, VT, ReturnType, 0, 0));
+      Outs.push_back(ISD::OutputArg(Flags, PartVT, VT, Ty, 0, 0));
   }
 }