[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, 30 insertions, 22 deletions

diff --git a/llvm/lib/CodeGen/Analysis.cpp b/llvm/lib/CodeGen/Analysis.cpp
index e7b9417..2ef96cc 100644
--- a/llvm/lib/CodeGen/Analysis.cpp
+++ b/llvm/lib/CodeGen/Analysis.cpp
@@ -69,18 +69,10 @@ unsigned llvm::ComputeLinearIndex(Type *Ty,
   return CurIndex + 1;
 }
 
-/// ComputeValueVTs - Given an LLVM IR type, compute a sequence of
-/// EVTs that represent all the individual underlying
-/// non-aggregate types that comprise it.
-///
-/// If Offsets is non-null, it points to a vector to be filled in
-/// with the in-memory offsets of each of the individual values.
-///
-void llvm::ComputeValueVTs(const TargetLowering &TLI, const DataLayout &DL,
-                           Type *Ty, SmallVectorImpl<EVT> &ValueVTs,
-                           SmallVectorImpl<EVT> *MemVTs,
-                           SmallVectorImpl<TypeSize> *Offsets,
-                           TypeSize StartingOffset) {
+void llvm::ComputeValueTypes(const DataLayout &DL, Type *Ty,
+                             SmallVectorImpl<Type *> &Types,
+                             SmallVectorImpl<TypeSize> *Offsets,
+                             TypeSize StartingOffset) {
   assert((Ty->isScalableTy() == StartingOffset.isScalable() ||
           StartingOffset.isZero()) &&
          "Offset/TypeSize mismatch!");
@@ -90,15 +82,13 @@ void llvm::ComputeValueVTs(const TargetLowering &TLI, const DataLayout &DL,
     // us to support structs with scalable vectors for operations that don't
     // need offsets.
     const StructLayout *SL = Offsets ? DL.getStructLayout(STy) : nullptr;
-    for (StructType::element_iterator EB = STy->element_begin(),
-                                      EI = EB,
+    for (StructType::element_iterator EB = STy->element_begin(), EI = EB,
                                       EE = STy->element_end();
          EI != EE; ++EI) {
       // Don't compute the element offset if we didn't get a StructLayout above.
       TypeSize EltOffset =
           SL ? SL->getElementOffset(EI - EB) : TypeSize::getZero();
-      ComputeValueVTs(TLI, DL, *EI, ValueVTs, MemVTs, Offsets,
-                      StartingOffset + EltOffset);
+      ComputeValueTypes(DL, *EI, Types, Offsets, StartingOffset + EltOffset);
     }
     return;
   }
@@ -107,21 +97,39 @@ void llvm::ComputeValueVTs(const TargetLowering &TLI, const DataLayout &DL,
     Type *EltTy = ATy->getElementType();
     TypeSize EltSize = DL.getTypeAllocSize(EltTy);
     for (unsigned i = 0, e = ATy->getNumElements(); i != e; ++i)
-      ComputeValueVTs(TLI, DL, EltTy, ValueVTs, MemVTs, Offsets,
-                      StartingOffset + i * EltSize);
+      ComputeValueTypes(DL, EltTy, Types, Offsets,
+                        StartingOffset + i * EltSize);
     return;
   }
   // Interpret void as zero return values.
   if (Ty->isVoidTy())
     return;
-  // Base case: we can get an EVT for this LLVM IR type.
-  ValueVTs.push_back(TLI.getValueType(DL, Ty));
-  if (MemVTs)
-    MemVTs->push_back(TLI.getMemValueType(DL, Ty));
+  Types.push_back(Ty);
   if (Offsets)
     Offsets->push_back(StartingOffset);
 }
 
+/// ComputeValueVTs - Given an LLVM IR type, compute a sequence of
+/// EVTs that represent all the individual underlying
+/// non-aggregate types that comprise it.
+///
+/// If Offsets is non-null, it points to a vector to be filled in
+/// with the in-memory offsets of each of the individual values.
+///
+void llvm::ComputeValueVTs(const TargetLowering &TLI, const DataLayout &DL,
+                           Type *Ty, SmallVectorImpl<EVT> &ValueVTs,
+                           SmallVectorImpl<EVT> *MemVTs,
+                           SmallVectorImpl<TypeSize> *Offsets,
+                           TypeSize StartingOffset) {
+  SmallVector<Type *> Types;
+  ComputeValueTypes(DL, Ty, Types, Offsets, StartingOffset);
+  for (Type *Ty : Types) {
+    ValueVTs.push_back(TLI.getValueType(DL, Ty));
+    if (MemVTs)
+      MemVTs->push_back(TLI.getMemValueType(DL, Ty));
+  }
+}
+
 void llvm::ComputeValueVTs(const TargetLowering &TLI, const DataLayout &DL,
                            Type *Ty, SmallVectorImpl<EVT> &ValueVTs,
                            SmallVectorImpl<EVT> *MemVTs,