[libc-commits] [libc] [libc][math] Impl bfloat16 lgamma function. (PR #199312)
Kiriti Ponduri via libc-commits
libc-commits at lists.llvm.org
Fri May 22 20:38:15 PDT 2026
https://github.com/udaykiriti updated https://github.com/llvm/llvm-project/pull/199312
>From 813062edac0e87f4c3a70021aa01d30e1522231e Mon Sep 17 00:00:00 2001
From: udaykiriti <udaykiriti9 at gmail.com>
Date: Sat, 23 May 2026 07:56:37 +0530
Subject: [PATCH 1/3] [libc][math] Impl bfloat16 lgamma function.
Signed-off-by: udaykiriti <udaykiriti9 at gmail.com>
---
libc/config/linux/x86_64/entrypoints.txt | 1 +
libc/src/__support/math/lgammabf16.h | 27 ++++++++++++++++++++
libc/src/math/CMakeLists.txt | 1 +
libc/src/math/generic/CMakeLists.txt | 9 +++++++
libc/src/math/generic/lgammabf16.cpp | 18 +++++++++++++
libc/src/math/lgammabf16.h | 21 +++++++++++++++
libc/test/src/math/smoke/CMakeLists.txt | 11 ++++++++
libc/test/src/math/smoke/lgammabf16_test.cpp | 19 ++++++++++++++
8 files changed, 107 insertions(+)
create mode 100644 libc/src/__support/math/lgammabf16.h
create mode 100644 libc/src/math/generic/lgammabf16.cpp
create mode 100644 libc/src/math/lgammabf16.h
create mode 100644 libc/test/src/math/smoke/lgammabf16_test.cpp
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);
+}
>From 85e7216b9195b47db04ad7ca671b14662d0b2a45 Mon Sep 17 00:00:00 2001
From: udaykiriti <udaykiriti9 at gmail.com>
Date: Sat, 23 May 2026 09:03:14 +0530
Subject: [PATCH 2/3] [libc][math] lgammabf16 cmake dependencies
Signed-off-by: udaykiriti <udaykiriti9 at gmail.com>
---
libc/src/math/generic/CMakeLists.txt | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index 375d03da28e7b..6a2615f92a53e 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -4875,7 +4875,7 @@ add_entrypoint_object(
HDRS
../lgammabf16.h
DEPENDS
- libc.src.__support.FPUtil.cast
+ libc.src.__support.math.lgammabf16
)
add_entrypoint_object(
>From 371e5674fea210ab1e5a0c44f5bcf26d86f27e28 Mon Sep 17 00:00:00 2001
From: udaykiriti <udaykiriti9 at gmail.com>
Date: Sat, 23 May 2026 09:07:58 +0530
Subject: [PATCH 3/3] [libc][math] Define lgammabf16 in
__support/math/CMakeLists.txt
Signed-off-by: udaykiriti <udaykiriti9 at gmail.com>
---
libc/src/__support/math/CMakeLists.txt | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/libc/src/__support/math/CMakeLists.txt b/libc/src/__support/math/CMakeLists.txt
index 9e3ec26cdc881..a389a37e37a0f 100644
--- a/libc/src/__support/math/CMakeLists.txt
+++ b/libc/src/__support/math/CMakeLists.txt
@@ -46,6 +46,17 @@ add_header_library(
libc.src.__support.macros.properties.types
)
+add_header_library(
+ lgammabf16
+ HDRS
+ lgammabf16.h
+ DEPENDS
+ libc.src.__support.FPUtil.cast
+ libc.src.__support.FPUtil.fp_bits
+ libc.src.math.logf
+ libc.src.math.sinf
+)
+
add_header_library(
acosh_float_constants
HDRS
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