[NFC][AMDGPU] Drop recursive types in LowerBufferFatPointers

[krzysz00]

Now that IRMover and the rest of LLVM don't allow recursive types, drop support for them from the clone of the IRMover code used when lowering buffer fat pointer operations.

[llvmbot]

@llvm/pr-subscribers-backend-amdgpu

Author: Krzysztof Drewniak (krzysz00)

Changes

Now that IRMover and the rest of LLVM don't allow recursive types, drop support for them from the clone of the IRMover code used when lowering buffer fat pointer operations.

---

Full diff: https://github.com/llvm/llvm-project/pull/137735.diff

1 Files Affected:

• (modified) llvm/lib/Target/AMDGPU/AMDGPULowerBufferFatPointers.cpp (+4-20)

diff --git a/llvm/lib/Target/AMDGPU/AMDGPULowerBufferFatPointers.cpp b/llvm/lib/Target/AMDGPU/AMDGPULowerBufferFatPointers.cpp
index 7163ad2aa7dca..284f6ede2b85b 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPULowerBufferFatPointers.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPULowerBufferFatPointers.cpp
@@ -267,7 +267,7 @@ namespace {
 class BufferFatPtrTypeLoweringBase : public ValueMapTypeRemapper {
   DenseMap<Type *, Type *> Map;
 
-  Type *remapTypeImpl(Type *Ty, SmallPtrSetImpl<StructType *> &Seen);
+  Type *remapTypeImpl(Type *Ty);
 
 protected:
   virtual Type *remapScalar(PointerType *PT) = 0;
@@ -305,8 +305,7 @@ class BufferFatPtrToStructTypeMap : public BufferFatPtrTypeLoweringBase {
 } // namespace
 
 // This code is adapted from the type remapper in lib/Linker/IRMover.cpp
-Type *BufferFatPtrTypeLoweringBase::remapTypeImpl(
-    Type *Ty, SmallPtrSetImpl<StructType *> &Seen) {
+Type *BufferFatPtrTypeLoweringBase::remapTypeImpl(Type *Ty) {
   Type **Entry = &Map[Ty];
   if (*Entry)
     return *Entry;
@@ -331,18 +330,11 @@ Type *BufferFatPtrTypeLoweringBase::remapTypeImpl(
   // require recursion.
   if (Ty->getNumContainedTypes() == 0 && IsUniqued)
     return *Entry = Ty;
-  if (!IsUniqued) {
-    // Create a dummy type for recursion purposes.
-    if (!Seen.insert(TyAsStruct).second) {
-      StructType *Placeholder = StructType::create(Ty->getContext());
-      return *Entry = Placeholder;
-    }
-  }
   bool Changed = false;
   SmallVector<Type *> ElementTypes(Ty->getNumContainedTypes(), nullptr);
   for (unsigned int I = 0, E = Ty->getNumContainedTypes(); I < E; ++I) {
     Type *OldElem = Ty->getContainedType(I);
-    Type *NewElem = remapTypeImpl(OldElem, Seen);
+    Type *NewElem = remapTypeImpl(OldElem);
     ElementTypes[I] = NewElem;
     Changed |= (OldElem != NewElem);
   }
@@ -366,13 +358,6 @@ Type *BufferFatPtrTypeLoweringBase::remapTypeImpl(
       return *Entry = StructType::get(Ty->getContext(), ElementTypes, IsPacked);
     SmallString<16> Name(STy->getName());
     STy->setName("");
-    Type **RecursionEntry = &Map[Ty];
-    if (*RecursionEntry) {
-      auto *Placeholder = cast<StructType>(*RecursionEntry);
-      Placeholder->setBody(ElementTypes, IsPacked);
-      Placeholder->setName(Name);
-      return *Entry = Placeholder;
-    }
     return *Entry = StructType::create(Ty->getContext(), ElementTypes, Name,
                                        IsPacked);
   }
@@ -380,8 +365,7 @@ Type *BufferFatPtrTypeLoweringBase::remapTypeImpl(
 }
 
 Type *BufferFatPtrTypeLoweringBase::remapType(Type *SrcTy) {
-  SmallPtrSet<StructType *, 2> Visited;
-  return remapTypeImpl(SrcTy, Visited);
+  return remapTypeImpl(SrcTy);
 }
 
 Type *BufferFatPtrToStructTypeMap::remapScalar(PointerType *PT) {