[clang] [OpenCL] Fix image2d_t qualifier for intel_sub_group_block_write_ui (PR #199232)

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<!--LLVM PR SUMMARY COMMENT-->

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Author: Igor Gorban (igorban-intel)

<details>
<summary>Changes</summary>

The intel_sub_group_block_write_ui[2,4,8] overloads for image2d_t were
declared with a read_only qualifier, both in opencl-c.h and in
OpenCLBuiltins.td.  A write operation cannot target a read_only image, and
the base intel_sub_group_block_write together with the analogous _us, _uc
and _ul aliases all correctly use write_only image2d_t.

Per the cl_intel_subgroups_short [1], cl_intel_subgroups_char [2] and
cl_intel_subgroups_long [3] specifications, the _ui aliases are added "for
naming consistency [...] There is no change to the description or behavior
of these functions" relative to the cl_intel_subgroups base, which uses
write_only image2d_t for writes.

The typo was introduced in b833bf6ae14f and preserved across all
later edits to this area.

Switch the qualifier from read_only to write_only in both opencl-c.h and
OpenCLBuiltins.td, and update intel-subgroups-builtins.cl to match the
corrected signature (the existing test was exercising the buggy overload).

[1] https://registry.khronos.org/OpenCL/extensions/intel/cl_intel_subgroups_short.html
[2] https://registry.khronos.org/OpenCL/extensions/intel/cl_intel_subgroups_char.html
[3] https://registry.khronos.org/OpenCL/extensions/intel/cl_intel_subgroups_long.html

Co-Authored-By: Claude Opus

---
Full diff: https://github.com/llvm/llvm-project/pull/199232.diff


3 Files Affected:

- (modified) clang/lib/Headers/opencl-c.h (+4-4) 
- (modified) clang/lib/Sema/OpenCLBuiltins.td (+4-4) 
- (modified) clang/test/SemaOpenCL/intel-subgroups-builtins.cl (+1-1) 


``````````diff
diff --git a/clang/lib/Headers/opencl-c.h b/clang/lib/Headers/opencl-c.h
index f4c7dbae2a00c..5d06df89acf1d 100644
--- a/clang/lib/Headers/opencl-c.h
+++ b/clang/lib/Headers/opencl-c.h
@@ -17553,10 +17553,10 @@ uint4      __ovld __conv intel_sub_group_block_read_ui4( const __global uint* p
 uint8      __ovld __conv intel_sub_group_block_read_ui8( const __global uint* p );
 
 #if defined(__opencl_c_images)
-void       __ovld __conv intel_sub_group_block_write_ui(read_only image2d_t, int2, uint);
-void       __ovld __conv intel_sub_group_block_write_ui2(read_only image2d_t, int2, uint2);
-void       __ovld __conv intel_sub_group_block_write_ui4(read_only image2d_t, int2, uint4);
-void       __ovld __conv intel_sub_group_block_write_ui8(read_only image2d_t, int2, uint8);
+void       __ovld __conv intel_sub_group_block_write_ui(write_only image2d_t, int2, uint);
+void       __ovld __conv intel_sub_group_block_write_ui2(write_only image2d_t, int2, uint2);
+void       __ovld __conv intel_sub_group_block_write_ui4(write_only image2d_t, int2, uint4);
+void       __ovld __conv intel_sub_group_block_write_ui8(write_only image2d_t, int2, uint8);
 #endif // defined(__opencl_c_images)
 
 #if defined(__opencl_c_read_write_images)
diff --git a/clang/lib/Sema/OpenCLBuiltins.td b/clang/lib/Sema/OpenCLBuiltins.td
index 356e54c09d02f..6049e87d3fcfe 100644
--- a/clang/lib/Sema/OpenCLBuiltins.td
+++ b/clang/lib/Sema/OpenCLBuiltins.td
@@ -1964,10 +1964,10 @@ let Extension = FuncExtIntelSubgroups in {
   def : Builtin<"intel_sub_group_block_read_ui4", [VectorType<UInt, 4>, PointerType<ConstType<UInt>, GlobalAS>], Attr.Convergent>;
   def : Builtin<"intel_sub_group_block_read_ui8", [VectorType<UInt, 8>, PointerType<ConstType<UInt>, GlobalAS>], Attr.Convergent>;
 
-  def : Builtin<"intel_sub_group_block_write_ui", [Void, ImageType<Image2d, "RO">, VectorType<Int, 2>, UInt], Attr.Convergent>;
-  def : Builtin<"intel_sub_group_block_write_ui2", [Void, ImageType<Image2d, "RO">, VectorType<Int, 2>, VectorType<UInt, 2>], Attr.Convergent>;
-  def : Builtin<"intel_sub_group_block_write_ui4", [Void, ImageType<Image2d, "RO">, VectorType<Int, 2>, VectorType<UInt, 4>], Attr.Convergent>;
-  def : Builtin<"intel_sub_group_block_write_ui8", [Void, ImageType<Image2d, "RO">, VectorType<Int, 2>, VectorType<UInt, 8>], Attr.Convergent>;
+  def : Builtin<"intel_sub_group_block_write_ui", [Void, ImageType<Image2d, "WO">, VectorType<Int, 2>, UInt], Attr.Convergent>;
+  def : Builtin<"intel_sub_group_block_write_ui2", [Void, ImageType<Image2d, "WO">, VectorType<Int, 2>, VectorType<UInt, 2>], Attr.Convergent>;
+  def : Builtin<"intel_sub_group_block_write_ui4", [Void, ImageType<Image2d, "WO">, VectorType<Int, 2>, VectorType<UInt, 4>], Attr.Convergent>;
+  def : Builtin<"intel_sub_group_block_write_ui8", [Void, ImageType<Image2d, "WO">, VectorType<Int, 2>, VectorType<UInt, 8>], Attr.Convergent>;
 
   def : Builtin<"intel_sub_group_block_write_ui", [Void, PointerType<UInt, GlobalAS>, UInt], Attr.Convergent>;
   def : Builtin<"intel_sub_group_block_write_ui2", [Void, PointerType<UInt, GlobalAS>, VectorType<UInt, 2>], Attr.Convergent>;
diff --git a/clang/test/SemaOpenCL/intel-subgroups-builtins.cl b/clang/test/SemaOpenCL/intel-subgroups-builtins.cl
index 473ab5296113d..be77471e89f80 100644
--- a/clang/test/SemaOpenCL/intel-subgroups-builtins.cl
+++ b/clang/test/SemaOpenCL/intel-subgroups-builtins.cl
@@ -123,7 +123,7 @@ void test_block_write_ui_global(__global uint *out, uint value, uint2 value2,
   intel_sub_group_block_write_ui8(out, value8);
 }
 
-void test_block_write_ui_image(read_only image2d_t image,
+void test_block_write_ui_image(write_only image2d_t image,
                                read_write image2d_t rw, int2 coord,
                                uint value, uint2 value2, uint4 value4,
                                uint8 value8) {

``````````

</details>


https://github.com/llvm/llvm-project/pull/199232