[clang] [OpenCL] Emit opencl.cxx.version metadata for C++ (PR #92140)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang-codegen

Author: Sven van Haastregt (svenvh)

<details>
<summary>Changes</summary>

Currently there is no way to tell whether an IR module was generated using `-cl-std=cl3.0` or `-cl-std=clc++2021`, i.e., whether the origin was a OpenCL C or C++ for OpenCL source.

Add new `opencl.cxx.version` named metadata when compiling C++.  Keep the `opencl.ocl.version` metadata to convey the compatible OpenCL C version.

Fixes https://github.com/llvm/llvm-project/issues/91912

---
Full diff: https://github.com/llvm/llvm-project/pull/92140.diff


2 Files Affected:

- (modified) clang/lib/CodeGen/CodeGenModule.cpp (+19-11) 
- (added) clang/test/CodeGenOpenCLCXX/version.clcpp (+21) 


``````````diff
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 489c08a4d4819..028ae9c5915db 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -1394,17 +1394,25 @@ void CodeGenModule::Release() {
 void CodeGenModule::EmitOpenCLMetadata() {
   // SPIR v2.0 s2.13 - The OpenCL version used by the module is stored in the
   // opencl.ocl.version named metadata node.
-  // C++ for OpenCL has a distinct mapping for versions compatibile with OpenCL.
-  auto Version = LangOpts.getOpenCLCompatibleVersion();
-  llvm::Metadata *OCLVerElts[] = {
-      llvm::ConstantAsMetadata::get(llvm::ConstantInt::get(
-          Int32Ty, Version / 100)),
-      llvm::ConstantAsMetadata::get(llvm::ConstantInt::get(
-          Int32Ty, (Version % 100) / 10))};
-  llvm::NamedMDNode *OCLVerMD =
-      TheModule.getOrInsertNamedMetadata("opencl.ocl.version");
-  llvm::LLVMContext &Ctx = TheModule.getContext();
-  OCLVerMD->addOperand(llvm::MDNode::get(Ctx, OCLVerElts));
+  // C++ for OpenCL has a distinct mapping for versions compatible with OpenCL.
+  auto CLVersion = LangOpts.getOpenCLCompatibleVersion();
+
+  auto EmitVersion = [this](StringRef MDName, int Version) {
+    llvm::Metadata *OCLVerElts[] = {
+        llvm::ConstantAsMetadata::get(
+            llvm::ConstantInt::get(Int32Ty, Version / 100)),
+        llvm::ConstantAsMetadata::get(
+            llvm::ConstantInt::get(Int32Ty, (Version % 100) / 10))};
+    llvm::NamedMDNode *OCLVerMD = TheModule.getOrInsertNamedMetadata(MDName);
+    llvm::LLVMContext &Ctx = TheModule.getContext();
+    OCLVerMD->addOperand(llvm::MDNode::get(Ctx, OCLVerElts));
+  };
+
+  EmitVersion("opencl.ocl.version", CLVersion);
+  if (LangOpts.OpenCLCPlusPlus) {
+    // In addition to the OpenCL compatible version, emit the C++ version.
+    EmitVersion("opencl.cxx.version", LangOpts.OpenCLCPlusPlusVersion);
+  }
 }
 
 void CodeGenModule::EmitBackendOptionsMetadata(
diff --git a/clang/test/CodeGenOpenCLCXX/version.clcpp b/clang/test/CodeGenOpenCLCXX/version.clcpp
new file mode 100644
index 0000000000000..2f2aa022afab2
--- /dev/null
+++ b/clang/test/CodeGenOpenCLCXX/version.clcpp
@@ -0,0 +1,21 @@
+// RUN: %clang_cc1 %s -triple "spir64-unknown-unknown" -emit-llvm -o - -cl-std=CL2.0 | FileCheck %s --check-prefix=CHECK-NO-CXX
+
+// RUN: %clang_cc1 %s -triple "spir64-unknown-unknown" -emit-llvm -o - -cl-std=clc++1.0 | FileCheck %s --check-prefix=CHECK-CXX100
+// RUN: %clang_cc1 %s -triple "spir64-unknown-unknown" -emit-llvm -o - -cl-std=clc++2021 | FileCheck %s --check-prefix=CHECK-CXX2021
+
+// This test checks that opencl.cxx.version metadata is emitted accordingly.
+// It avoids any C++ features to enable checking that the metadata is not emitted in non-C++ mode.
+
+kernel void foo() {}
+
+// CHECK-NO-CXX-NOT: opencl.cxx.version
+
+// CHECK-CXX100-DAG: !opencl.ocl.version = !{[[OCL:![0-9]+]]}
+// CHECK-CXX100-DAG: !opencl.cxx.version = !{[[CXX:![0-9]+]]}
+// CHECK-CXX100-DAG: [[OCL]] = !{i32 2, i32 0}
+// CHECK-CXX100-DAG: [[CXX]] = !{i32 1, i32 0}
+
+// CHECK-CXX2021-DAG: !opencl.ocl.version = !{[[OCL:![0-9]+]]}
+// CHECK-CXX2021-DAG: !opencl.cxx.version = !{[[CXX:![0-9]+]]}
+// CHECK-CXX2021-DAG: [[OCL]] = !{i32 3, i32 0}
+// CHECK-CXX2021-DAG: [[CXX]] = !{i32 2021, i32 0}

``````````

</details>


https://github.com/llvm/llvm-project/pull/92140