[PATCH] D104902: [OpaquePtr] Allow globals with opaque pointer value type

[Nikita Popov via Phabricator via llvm-commits]

nikic created this revision.
nikic added a reviewer: opaque-pointers.
Herald added subscribers: dexonsmith, hiraditya.
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Herald added a subscriber: llvm-commits.

Do this by making opaque pointers a valid pointer element type, for which we implicitly create an opaque pointer (moving the logic from getPointerTo into PointerType::get).

We'll never create something like a "pointer to opaque pointer", but accept it in the API, because a lot of code reasonably assumes that you can create a pointer to pointer type.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D104902

Files:
  llvm/lib/IR/Type.cpp
  llvm/test/Assembler/opaque-ptr.ll


Index: llvm/test/Assembler/opaque-ptr.ll
===================================================================
--- llvm/test/Assembler/opaque-ptr.ll
+++ llvm/test/Assembler/opaque-ptr.ll
@@ -1,6 +1,9 @@
 ; RUN: llvm-as < %s | llvm-dis | llvm-as | llvm-dis | FileCheck %s
 ; RUN: verify-uselistorder %s
 
+; CHECK: @global = external global ptr
+ at global = external global ptr
+
 ; CHECK: define ptr @f(ptr %a) {
 ; CHECK:     %b = bitcast ptr %a to ptr
 ; CHECK:     ret ptr %b
Index: llvm/lib/IR/Type.cpp
===================================================================
--- llvm/lib/IR/Type.cpp
+++ llvm/lib/IR/Type.cpp
@@ -690,7 +690,9 @@
 
   LLVMContextImpl *CImpl = EltTy->getContext().pImpl;
 
-  if (CImpl->ForceOpaquePointers)
+  // Create opaque pointer for pointer to opaque pointer.
+  if (CImpl->ForceOpaquePointers ||
+      (isa<PointerType>(EltTy) && cast<PointerType>(EltTy)->isOpaque()))
     return get(EltTy->getContext(), AddressSpace);
 
   // Since AddressSpace #0 is the common case, we special case it.
@@ -729,19 +731,13 @@
 }
 
 PointerType *Type::getPointerTo(unsigned AddrSpace) const {
-  // Pointer to opaque pointer is opaque pointer.
-  if (auto *PTy = dyn_cast<PointerType>(this))
-    if (PTy->isOpaque())
-      return PointerType::get(getContext(), AddrSpace);
-
   return PointerType::get(const_cast<Type*>(this), AddrSpace);
 }
 
 bool PointerType::isValidElementType(Type *ElemTy) {
   return !ElemTy->isVoidTy() && !ElemTy->isLabelTy() &&
          !ElemTy->isMetadataTy() && !ElemTy->isTokenTy() &&
-         !ElemTy->isX86_AMXTy() &&
-         !(ElemTy->isPointerTy() && cast<PointerType>(ElemTy)->isOpaque());
+         !ElemTy->isX86_AMXTy();
 }
 
 bool PointerType::isLoadableOrStorableType(Type *ElemTy) {


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