Add clang patch to enable BFloat16 for SPIR/SPIR-V

.github/workflows/on-push-verification-in-tree.yml

@@ -35,9 +35,19 @@ jobs:
       - name: Checkout opencl-clang sources for action files
         uses: actions/checkout@a5ac7e51b41094c92402da3b24376905380afc29 # v4.1.6
 
+      # This step will fail when the branch naming scheme 'ocl-open-XXX' changes!
+      - name: Parse LLVM version from branch name
+        id: check-llvm-version
+        run: |
+          BRANCH="${{ github.base_ref }}"          # on: pull_request, otherwise null
+          BRANCH=${BRANCH:-${{ github.ref_name }}} # on: push
+          LLVM_VERSION_LONG=$(echo $BRANCH | grep -oP '\d+') # Eg. 190 for LLVM 19
+          LLVM_VERSION_SHORT=${LLVM_VERSION_LONG::-1}        # Eg. 19  for LLVM 19
+          echo "llvm_version=$LLVM_VERSION_SHORT" >> $GITHUB_OUTPUT
+
       - name: Run build-opencl-clang action
         uses: ./.github/actions/build-opencl-clang
         with:
-          ref_llvm: main
-          ref_translator: main
+          ref_llvm: release/${{ steps.check-llvm-version.outputs.llvm_version }}.x
+          ref_translator: llvm_release_${{ steps.check-llvm-version.outputs.llvm_version }}0
           ref_opencl-clang: ${{ github.ref }}

cmake/modules/CMakeFunctions.cmake

@@ -141,7 +141,7 @@ function(apply_patches repo_dir patches_dir base_revision target_branch)
                 message(STATUS "[OPENCL-CLANG] Not present - ${patching_log}")
             endif()
         endforeach(patch)
-    elsef(patches_needed EQUAL 0) # The target branch already exists
+    elseif(patches_needed EQUAL 0) # The target branch already exists
         execute_process( # Check it out
             COMMAND ${GIT_EXECUTABLE} checkout ${target_branch}
             WORKING_DIRECTORY ${repo_dir}

patches/clang/0001-Clang-Enable-BFloat16-for-SPIR-SPIR-V.patch

@@ -0,0 +1,36 @@
+From 6e240c1b150b4623d126539320b00375f6ee4ed6 Mon Sep 17 00:00:00 2001
+From: Wenju He <[email protected]>
+Date: Fri, 21 Nov 2025 05:37:58 +0100
+Subject: [PATCH] [Clang] Enable BFloat16 for SPIR/SPIR-V
+
+---
+ clang/lib/Basic/Targets/SPIR.h | 6 +++---
+ 1 file changed, 3 insertions(+), 3 deletions(-)
+
+diff --git a/clang/lib/Basic/Targets/SPIR.h b/clang/lib/Basic/Targets/SPIR.h
+index 37cf9d7921ba..f593971bb3a0 100644
+--- a/clang/lib/Basic/Targets/SPIR.h
++++ b/clang/lib/Basic/Targets/SPIR.h
+@@ -101,6 +101,9 @@ protected:
+     UseAddrSpaceMapMangling = true;
+     HasLegalHalfType = true;
+     HasFloat16 = true;
++    HasBFloat16 = true;
++    BFloat16Width = BFloat16Align = 16;
++    BFloat16Format = &llvm::APFloat::BFloat();
+     // Define available target features
+     // These must be defined in sorted order!
+     NoAsmVariants = true;
+@@ -384,9 +387,6 @@ public:
+     resetDataLayout("e-i64:64-v16:16-v24:32-v32:32-v48:64-"
+                     "v96:128-v192:256-v256:256-v512:512-v1024:1024-G1-P4-A0");
+
+-    BFloat16Width = BFloat16Align = 16;
+-    BFloat16Format = &llvm::APFloat::BFloat();
+-
+     HasLegalHalfType = true;
+     HasFloat16 = true;
+     HalfArgsAndReturns = true;
+-- 
+2.39.1
+