[Clang] Support __bf16 type for SPIR/SPIR-V

[wenju-he]

SPIR/SPIR-V are generic targets. Assume they support __bf16.

[llvmbot]

@llvm/pr-subscribers-clang

Author: Wenju He (wenju-he)

Changes

SPIR/SPIR-V are generic targets. Assume they support __bf16.

---

Full diff: https://github.com/llvm/llvm-project/pull/169012.diff

3 Files Affected:

• (modified) clang/lib/Basic/Targets/SPIR.h (+4-5)
• (added) clang/test/CodeGenOpenCL/__bf16.cl (+31)
• (modified) clang/test/SemaSYCL/bf16.cpp (+4-3)

diff --git a/clang/lib/Basic/Targets/SPIR.h b/clang/lib/Basic/Targets/SPIR.h
index 22b2799518dd0..332bf79e2babd 100644
--- a/clang/lib/Basic/Targets/SPIR.h
+++ b/clang/lib/Basic/Targets/SPIR.h
@@ -108,6 +108,10 @@ class LLVM_LIBRARY_VISIBILITY BaseSPIRTargetInfo : public TargetInfo {
     UseAddrSpaceMapMangling = true;
     HasFastHalfType = true;
     HasFloat16 = true;
+    HasBFloat16 = true;
+    HasFullBFloat16 = true;
+    BFloat16Width = BFloat16Align = 16;
+    BFloat16Format = &llvm::APFloat::BFloat();
     // Define available target features
     // These must be defined in sorted order!
     NoAsmVariants = true;
@@ -427,9 +431,6 @@ class LLVM_LIBRARY_VISIBILITY SPIRV64AMDGCNTargetInfo final
     resetDataLayout("e-i64:64-v16:16-v24:32-v32:32-v48:64-v96:128-v192:256-"
                     "v256:256-v512:512-v1024:1024-n32:64-S32-G1-P4-A0");
 
-    BFloat16Width = BFloat16Align = 16;
-    BFloat16Format = &llvm::APFloat::BFloat();
-
     HasFastHalfType = true;
     HasFloat16 = true;
     HalfArgsAndReturns = true;
@@ -437,8 +438,6 @@ class LLVM_LIBRARY_VISIBILITY SPIRV64AMDGCNTargetInfo final
     MaxAtomicPromoteWidth = MaxAtomicInlineWidth = 64;
   }
 
-  bool hasBFloat16Type() const override { return true; }
-
   ArrayRef<const char *> getGCCRegNames() const override;
 
   BuiltinVaListKind getBuiltinVaListKind() const override {
diff --git a/clang/test/CodeGenOpenCL/__bf16.cl b/clang/test/CodeGenOpenCL/__bf16.cl
new file mode 100644
index 0000000000000..a40a795bc1600
--- /dev/null
+++ b/clang/test/CodeGenOpenCL/__bf16.cl
@@ -0,0 +1,31 @@
+// RUN: %clang_cc1 %s -cl-std=cl3.0 -emit-llvm -o - -triple spir-unknown-unknown | FileCheck %s
+// RUN: %clang_cc1 %s -cl-std=cl3.0 -emit-llvm -o - -triple spirv64-unknown-unknown | FileCheck %s
+
+kernel void test(global __bf16 *a, global __bf16 *b){
+// CHECK-LABEL: spir_kernel void @test(
+// CHECK: fadd bfloat
+// CHECK: fsub bfloat
+// CHECK: fmul bfloat
+// CHECK: fdiv bfloat
+
+  *b += *a;
+  *b -= *a;
+  *b *= *a;
+  *b /= *a;
+}
+
+typedef __bf16 __bf16v4 __attribute((ext_vector_type(4)));
+
+kernel void test_v4(global __bf16v4 *a, global __bf16v4 *b){
+// CHECK-LABEL: spir_kernel void @test_v4(
+// CHECK: fadd <4 x bfloat>
+// CHECK: fsub <4 x bfloat>
+// CHECK: fmul <4 x bfloat>
+// CHECK: fdiv <4 x bfloat>
+
+  *b += *a;
+  *b -= *a;
+  *b *= *a;
+  *b /= *a;
+}
+
diff --git a/clang/test/SemaSYCL/bf16.cpp b/clang/test/SemaSYCL/bf16.cpp
index d1b4776f34044..2ffb277b4eea1 100644
--- a/clang/test/SemaSYCL/bf16.cpp
+++ b/clang/test/SemaSYCL/bf16.cpp
@@ -1,8 +1,9 @@
 // RUN: %clang_cc1 -triple spir64 -aux-triple x86_64-unknown-linux-gnu -fsycl-is-device -verify -fsyntax-only %s
+// expected-no-diagnostics
 
 template <typename Name, typename Func>
 __attribute__((sycl_kernel)) void kernel(const Func &kernelFunc) {
-  kernelFunc(); // expected-note {{called by 'kernel}}
+  kernelFunc();
 }
 
 void host_ok(void) {
@@ -11,9 +12,9 @@ void host_ok(void) {
 
 int main()
 {  host_ok();
-  __bf16 var; // expected-note {{'var' defined here}}
+  __bf16 var;
   kernel<class variables>([=]() {
-    (void)var; // expected-error {{'var' requires 16 bit size '__bf16' type support, but target 'spir64' does not support it}}
+    (void)var;
     int B = sizeof(__bf16);
   });
 

[Copilot]

Pull Request Overview

This PR enables __bf16 (bfloat16) type support for SPIR and SPIR-V targets by configuring the base target class with bfloat16 properties and removing target-specific overrides that are now redundant.

Key changes:

• Configured bfloat16 support in the base BaseSPIRTargetInfo class, making it available to all SPIR/SPIR-V targets
• Removed redundant bfloat16 configuration from SPIRV64AMDGCNTargetInfo subclass
• Updated test expectations to reflect that __bf16 is now supported without diagnostics

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
clang/test/SemaSYCL/bf16.cpp	Updated test expectations to verify __bf16 is now accepted without errors on SPIR targets
clang/test/CodeGenOpenCL/__bf16.cl	Added new test validating code generation for __bf16 operations on SPIR/SPIR-V targets
clang/lib/Basic/Targets/SPIR.h	Moved bfloat16 configuration to base class and removed redundant subclass overrides

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🐧 Linux x64 Test Results

• 111349 tests passed
• 4435 tests skipped