[clang] a823a2a - [SPIR-V] Do not allow AS(2) to convert to generic (#175275)

[via cfe-commits]

Author: Joseph Huber
Date: 2026-01-12T14:49:08Z
New Revision: a823a2ab6d9032be7cf037ec2e1db3ec501659db

URL: https://github.com/llvm/llvm-project/commit/a823a2ab6d9032be7cf037ec2e1db3ec501659db
DIFF: https://github.com/llvm/llvm-project/commit/a823a2ab6d9032be7cf037ec2e1db3ec501659db.diff

LOG: [SPIR-V] Do not allow AS(2) to convert to generic (#175275)

Summary:
The original logic permitted this, while it's not permitted by the
standard.

---------

Co-authored-by: Dmitry Sidorov <18708689+MrSidims at users.noreply.github.com>

Added: 
    

Modified: 
    clang/lib/Basic/Targets/SPIR.h
    clang/test/Sema/spirv-address-space.c

Removed: 
    


################################################################################
diff  --git a/clang/lib/Basic/Targets/SPIR.h b/clang/lib/Basic/Targets/SPIR.h
index 8030aa9e10370..ea992b0e01dbe 100644
--- a/clang/lib/Basic/Targets/SPIR.h
+++ b/clang/lib/Basic/Targets/SPIR.h
@@ -320,12 +320,13 @@ class LLVM_LIBRARY_VISIBILITY BaseSPIRVTargetInfo : public BaseSPIRTargetInfo {
 
   virtual bool isAddressSpaceSupersetOf(LangAS A, LangAS B) const override {
     // The generic space AS(4) is a superset of all the other address
-    // spaces used by the backend target.
+    // spaces used by the backend target except constant address space.
     return A == B || ((A == LangAS::Default ||
                        (isTargetAddressSpace(A) &&
                         toTargetAddressSpace(A) == /*Generic=*/4)) &&
                       isTargetAddressSpace(B) &&
-                      toTargetAddressSpace(B) <= /*Generic=*/4);
+                      (toTargetAddressSpace(B) <= /*Generic=*/4 &&
+                       toTargetAddressSpace(B) != /*Constant=*/2));
   }
 
   void getTargetDefines(const LangOptions &Opts,

diff  --git a/clang/test/Sema/spirv-address-space.c b/clang/test/Sema/spirv-address-space.c
index 7ec41fd79bd96..fc212577b4841 100644
--- a/clang/test/Sema/spirv-address-space.c
+++ b/clang/test/Sema/spirv-address-space.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; } // expected-error {{returning '_AS5 void *' from a function with result type 'void *' changes address space of pointer}}
@@ -18,4 +18,3 @@ void *pc(void __attribute__((opencl_local)) *p) { return p; } // expected-error
 void _AS1 *r0(void _AS1 *p) { return p; }
 void _AS1 *r1(void *p) { return p; } // expected-error {{returning 'void *' from a function with result type '_AS1 void *' changes address space of pointer}}
 void _AS1 *r2(void *p) { return (void _AS1 *)p; }
-