[clang] [Clang] Support __bf16 type for SPIR/SPIR-V (PR #169012)
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Thu Nov 20 23:54:45 PST 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang
Author: Wenju He (wenju-he)
<details>
<summary>Changes</summary>
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
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);
});
``````````
</details>
https://github.com/llvm/llvm-project/pull/169012
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