From 8d11a8dd9ec92399d1d0c54ea8a1f311e4917fb1 Mon Sep 17 00:00:00 2001
From: Krzysztof Drewniak <Krzysztof.Drewniak@amd.com>
Date: Mon, 28 Apr 2025 23:39:53 +0000
Subject: [PATCH] [NFC][AMDGPU] Drop recursive types in LowerBufferFatPointers

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.
---
 .../AMDGPU/AMDGPULowerBufferFatPointers.cpp   | 24 ++++---------------
 1 file changed, 4 insertions(+), 20 deletions(-)

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) {