[clang] [AMDGPU] Do not allow the region address space to be converted to generic (PR #117171)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-amdgpu

Author: Joseph Huber (jhuber6)

<details>
<summary>Changes</summary>

Summary:
Previous changes relaxed the address space rules based on what the
target says about them. This accidentally included the AS(2) region as
convertible to generic. Simply check for AS(2) and reject it.


---
Full diff: https://github.com/llvm/llvm-project/pull/117171.diff


2 Files Affected:

- (modified) clang/lib/Basic/Targets/AMDGPU.h (+2-1) 
- (modified) clang/test/Sema/amdgcn-address-spaces.c (+1-1) 


``````````diff
diff --git a/clang/lib/Basic/Targets/AMDGPU.h b/clang/lib/Basic/Targets/AMDGPU.h
index db7a095ba2a4fe..ea4189cdea47da 100644
--- a/clang/lib/Basic/Targets/AMDGPU.h
+++ b/clang/lib/Basic/Targets/AMDGPU.h
@@ -120,7 +120,8 @@ class LLVM_LIBRARY_VISIBILITY AMDGPUTargetInfo final : public TargetInfo {
               toTargetAddressSpace(A) == llvm::AMDGPUAS::FLAT_ADDRESS)) &&
             isTargetAddressSpace(B) &&
             toTargetAddressSpace(B) >= llvm::AMDGPUAS::FLAT_ADDRESS &&
-            toTargetAddressSpace(B) <= llvm::AMDGPUAS::PRIVATE_ADDRESS);
+            toTargetAddressSpace(B) <= llvm::AMDGPUAS::PRIVATE_ADDRESS &&
+            toTargetAddressSpace(B) != llvm::AMDGPUAS::REGION_ADDRESS);
   }
 
   uint64_t getMaxPointerWidth() const override {
diff --git a/clang/test/Sema/amdgcn-address-spaces.c b/clang/test/Sema/amdgcn-address-spaces.c
index 50c12993ac69b8..70545db920c807 100644
--- a/clang/test/Sema/amdgcn-address-spaces.c
+++ b/clang/test/Sema/amdgcn-address-spaces.c
@@ -9,7 +9,7 @@
 #define _AS999 __attribute__((address_space(999)))
 
 void *p1(void _AS1 *p) { return p; }
-void *p2(void _AS2 *p) { return p; }
+void *p2(void _AS2 *p) { return p; } // expected-error {{returning '_AS2 void *' from a function with result type 'void *' changes address space of pointer}}
 void *p3(void _AS3 *p) { return p; }
 void *p4(void _AS4 *p) { return p; }
 void *p5(void _AS5 *p) { return p; }

``````````

</details>


https://github.com/llvm/llvm-project/pull/117171