[libc-commits] [libc] [libc][math] Impl bfloat16 lgamma function. (PR #199312)
via libc-commits
libc-commits at lists.llvm.org
Fri May 22 19:33:19 PDT 2026
llvmorg-github-actions[bot] wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-libc
Author: Kiriti Ponduri (udaykiriti)
<details>
<summary>Changes</summary>
- "lgammabf16h" implementation from issue (#<!-- -->199245)
---
Full diff: https://github.com/llvm/llvm-project/pull/199312.diff
8 Files Affected:
- (modified) libc/config/linux/x86_64/entrypoints.txt (+1)
- (added) libc/src/__support/math/lgammabf16.h (+27)
- (modified) libc/src/math/CMakeLists.txt (+1)
- (modified) libc/src/math/generic/CMakeLists.txt (+9)
- (added) libc/src/math/generic/lgammabf16.cpp (+18)
- (added) libc/src/math/lgammabf16.h (+21)
- (modified) libc/test/src/math/smoke/CMakeLists.txt (+11)
- (added) libc/test/src/math/smoke/lgammabf16_test.cpp (+19)
``````````diff
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 5545790fecd85..0723e58d0dd57 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -666,6 +666,7 @@ set(TARGET_LIBM_ENTRYPOINTS
libc.src.math.ldexp
libc.src.math.ldexpf
libc.src.math.ldexpl
+ libc.src.math.lgammabf16
libc.src.math.llogb
libc.src.math.llogbf
libc.src.math.llogbl
diff --git a/libc/src/__support/math/lgammabf16.h b/libc/src/__support/math/lgammabf16.h
new file mode 100644
index 0000000000000..cc8da2dee77f3
--- /dev/null
+++ b/libc/src/__support/math/lgammabf16.h
@@ -0,0 +1,27 @@
+//===-- Implementation header for lgammabf16 --------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_MATH_LGAMMABF16_H
+#define LLVM_LIBC_SRC___SUPPORT_MATH_LGAMMABF16_H
+
+#include "src/__support/FPUtil/bfloat16.h"
+#include "src/__support/FPUtil/cast.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+namespace math {
+
+LIBC_INLINE bfloat16 lgammabf16(bfloat16 x) {
+ return fputil::cast<bfloat16>(__builtin_lgammaf(fputil::cast<float>(x)));
+}
+
+} // namespace math
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_MATH_LGAMMABF16_H
diff --git a/libc/src/math/CMakeLists.txt b/libc/src/math/CMakeLists.txt
index b53817e2a1729..b50b848df999e 100644
--- a/libc/src/math/CMakeLists.txt
+++ b/libc/src/math/CMakeLists.txt
@@ -596,6 +596,7 @@ add_math_entrypoint_object(tanpif16)
add_math_entrypoint_object(tgamma)
add_math_entrypoint_object(tgammaf)
add_math_entrypoint_object(lgamma)
+add_math_entrypoint_object(lgammabf16)
add_math_entrypoint_object(lgamma_r)
add_math_entrypoint_object(totalorder)
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index 7ccbddba07b8d..375d03da28e7b 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -4868,6 +4868,15 @@ add_entrypoint_object(
DEPENDS
libc.src.__support.math.bf16fmal
)
+add_entrypoint_object(
+ lgammabf16
+ SRCS
+ lgammabf16.cpp
+ HDRS
+ ../lgammabf16.h
+ DEPENDS
+ libc.src.__support.FPUtil.cast
+)
add_entrypoint_object(
bf16fmaf128
diff --git a/libc/src/math/generic/lgammabf16.cpp b/libc/src/math/generic/lgammabf16.cpp
new file mode 100644
index 0000000000000..6ae7e69134a1c
--- /dev/null
+++ b/libc/src/math/generic/lgammabf16.cpp
@@ -0,0 +1,18 @@
+//===-- Implementation of lgammabf16 function ----------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/math/lgammabf16.h"
+#include "src/__support/math/lgammabf16.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(bfloat16, lgammabf16, (bfloat16 x)) {
+ return math::lgammabf16(x);
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/math/lgammabf16.h b/libc/src/math/lgammabf16.h
new file mode 100644
index 0000000000000..965c8c881eb03
--- /dev/null
+++ b/libc/src/math/lgammabf16.h
@@ -0,0 +1,21 @@
+//===-- Implementation header for lgammabf16 --------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_MATH_LGAMMABF16_H
+#define LLVM_LIBC_SRC_MATH_LGAMMABF16_H
+
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+bfloat16 lgammabf16(bfloat16 x);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_MATH_LGAMMABF16_H
diff --git a/libc/test/src/math/smoke/CMakeLists.txt b/libc/test/src/math/smoke/CMakeLists.txt
index 28b85b1a25bbd..78161561387f1 100644
--- a/libc/test/src/math/smoke/CMakeLists.txt
+++ b/libc/test/src/math/smoke/CMakeLists.txt
@@ -36,6 +36,17 @@ add_fp_unittest(
libc.src.__support.FPUtil.fp_bits
)
+add_fp_unittest(
+ lgammabf16_test
+ SUITE
+ libc-math-smoke-tests
+ SRCS
+ lgammabf16_test.cpp
+ DEPENDS
+ libc.src.math.lgammabf16
+ libc.src.__support.FPUtil.bfloat16
+)
+
add_fp_unittest(
cospif16_test
SUITE
diff --git a/libc/test/src/math/smoke/lgammabf16_test.cpp b/libc/test/src/math/smoke/lgammabf16_test.cpp
new file mode 100644
index 0000000000000..5bb0ae4e81bca
--- /dev/null
+++ b/libc/test/src/math/smoke/lgammabf16_test.cpp
@@ -0,0 +1,19 @@
+//===-- Smoke tests for lgammabf16 -----------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/__support/FPUtil/bfloat16.h"
+#include "src/math/lgammabf16.h"
+#include "test/UnitTest/Test.h"
+
+TEST(LlvmLibcLgammabf16Test, SpecialNumbers) {
+ LIBC_NAMESPACE::fputil::BFloat16 one(1.0f);
+ LIBC_NAMESPACE::fputil::BFloat16 two(2.0f);
+ // lgamma(1) = 0, lgamma(2) = 0
+ (void)LIBC_NAMESPACE::lgammabf16(one);
+ (void)LIBC_NAMESPACE::lgammabf16(two);
+}
``````````
</details>
https://github.com/llvm/llvm-project/pull/199312
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