[libc-commits] [libc] [llvm] [libc][math] Add tgammabf16 math support for bfloat16. (PR #208689)

Vedant Neve via libc-commits libc-commits at lists.llvm.org
Mon Jul 13 06:45:05 PDT 2026


https://github.com/0bVdnt updated https://github.com/llvm/llvm-project/pull/208689

>From 7d19fcec11b40bddb1a203f2c02f7011d58bb1bf Mon Sep 17 00:00:00 2001
From: Vedant Neve <vedantneve13 at gmail.com>
Date: Tue, 7 Jul 2026 11:42:52 +0530
Subject: [PATCH] [libc][math] Add bfloat16 tgamma function

This patch implements the `tgammabf16` function for LLVM-libc.

Fixes #207495

Signed-off-by: Vedant Neve <vedantneve13 at gmail.com>
---
 libc/config/baremetal/aarch64/entrypoints.txt |   1 +
 libc/config/baremetal/arm/entrypoints.txt     |   1 +
 libc/config/baremetal/riscv/entrypoints.txt   |   1 +
 libc/config/darwin/aarch64/entrypoints.txt    |   1 +
 libc/config/darwin/x86_64/entrypoints.txt     |   1 +
 libc/config/freebsd/x86_64/entrypoints.txt    |   1 +
 libc/config/gpu/amdgpu/entrypoints.txt        |   1 +
 libc/config/gpu/nvptx/entrypoints.txt         |   1 +
 libc/config/linux/aarch64/entrypoints.txt     |   1 +
 libc/config/linux/arm/entrypoints.txt         |   1 +
 libc/config/linux/riscv/entrypoints.txt       |   1 +
 libc/config/linux/x86_64/entrypoints.txt      |   1 +
 libc/config/windows/entrypoints.txt           |   2 +-
 libc/shared/math.h                            |   1 +
 libc/shared/math/tgammabf16.h                 |  23 +++
 libc/src/__support/math/CMakeLists.txt        |  19 ++
 libc/src/__support/math/tgammabf16.h          | 179 ++++++++++++++++++
 libc/src/math/CMakeLists.txt                  |   1 +
 libc/src/math/generic/CMakeLists.txt          |  10 +
 libc/src/math/generic/tgammabf16.cpp          |  18 ++
 libc/src/math/tgammabf16.h                    |  21 ++
 libc/test/shared/CMakeLists.txt               |   1 +
 libc/test/shared/shared_math_test.cpp         |   3 +
 libc/test/src/math/CMakeLists.txt             |  12 ++
 libc/test/src/math/smoke/CMakeLists.txt       |  13 ++
 libc/test/src/math/smoke/tgammabf16_test.cpp  |  79 ++++++++
 libc/test/src/math/tgammabf16_test.cpp        |  42 ++++
 libc/utils/MPFRWrapper/MPCommon.cpp           |   6 +
 libc/utils/MPFRWrapper/MPCommon.h             |   1 +
 libc/utils/MPFRWrapper/MPFRUtils.cpp          |   2 +
 libc/utils/MPFRWrapper/MPFRUtils.h            |   1 +
 .../llvm-project-overlay/libc/BUILD.bazel     |  26 +++
 32 files changed, 471 insertions(+), 1 deletion(-)
 create mode 100644 libc/shared/math/tgammabf16.h
 create mode 100644 libc/src/__support/math/tgammabf16.h
 create mode 100644 libc/src/math/generic/tgammabf16.cpp
 create mode 100644 libc/src/math/tgammabf16.h
 create mode 100644 libc/test/src/math/smoke/tgammabf16_test.cpp
 create mode 100644 libc/test/src/math/tgammabf16_test.cpp

diff --git a/libc/config/baremetal/aarch64/entrypoints.txt b/libc/config/baremetal/aarch64/entrypoints.txt
index 149c790bb2448..5db00c527ef52 100644
--- a/libc/config/baremetal/aarch64/entrypoints.txt
+++ b/libc/config/baremetal/aarch64/entrypoints.txt
@@ -869,6 +869,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
   libc.src.math.setpayloadsigbf16
   libc.src.math.sqrtbf16
   libc.src.math.tanbf16
+  libc.src.math.tgammabf16
   libc.src.math.truncbf16
   libc.src.math.totalorderbf16
   libc.src.math.totalordermagbf16
diff --git a/libc/config/baremetal/arm/entrypoints.txt b/libc/config/baremetal/arm/entrypoints.txt
index 8a8ab3d6a78fd..e9e34e59d3688 100644
--- a/libc/config/baremetal/arm/entrypoints.txt
+++ b/libc/config/baremetal/arm/entrypoints.txt
@@ -880,6 +880,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
   libc.src.math.setpayloadsigbf16
   libc.src.math.sqrtbf16
   libc.src.math.tanbf16
+  libc.src.math.tgammabf16
   libc.src.math.truncbf16
   libc.src.math.totalorderbf16
   libc.src.math.totalordermagbf16
diff --git a/libc/config/baremetal/riscv/entrypoints.txt b/libc/config/baremetal/riscv/entrypoints.txt
index d0b8f091cd6e2..b22952210b0d7 100644
--- a/libc/config/baremetal/riscv/entrypoints.txt
+++ b/libc/config/baremetal/riscv/entrypoints.txt
@@ -877,6 +877,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
   libc.src.math.setpayloadsigbf16
   libc.src.math.sqrtbf16
   libc.src.math.tanbf16
+  libc.src.math.tgammabf16
   libc.src.math.truncbf16
   libc.src.math.totalorderbf16
   libc.src.math.totalordermagbf16
diff --git a/libc/config/darwin/aarch64/entrypoints.txt b/libc/config/darwin/aarch64/entrypoints.txt
index eeb9ec244b415..1b6174a569d2d 100644
--- a/libc/config/darwin/aarch64/entrypoints.txt
+++ b/libc/config/darwin/aarch64/entrypoints.txt
@@ -690,6 +690,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
   libc.src.math.setpayloadsigbf16
   libc.src.math.sqrtbf16
   libc.src.math.tanbf16
+  libc.src.math.tgammabf16
   libc.src.math.truncbf16
   libc.src.math.totalorderbf16
   libc.src.math.totalordermagbf16
diff --git a/libc/config/darwin/x86_64/entrypoints.txt b/libc/config/darwin/x86_64/entrypoints.txt
index 18184e8136a9e..e561cdae925f6 100644
--- a/libc/config/darwin/x86_64/entrypoints.txt
+++ b/libc/config/darwin/x86_64/entrypoints.txt
@@ -306,6 +306,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
   libc.src.math.setpayloadsigbf16
   libc.src.math.sqrtbf16
   libc.src.math.tanbf16
+  libc.src.math.tgammabf16
   libc.src.math.truncbf16
   libc.src.math.totalorderbf16
   libc.src.math.totalordermagbf16
diff --git a/libc/config/freebsd/x86_64/entrypoints.txt b/libc/config/freebsd/x86_64/entrypoints.txt
index df6c0f907725b..8ea696469cc3c 100644
--- a/libc/config/freebsd/x86_64/entrypoints.txt
+++ b/libc/config/freebsd/x86_64/entrypoints.txt
@@ -629,6 +629,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
   libc.src.math.setpayloadsigbf16
   libc.src.math.sqrtbf16
   libc.src.math.tanbf16
+  libc.src.math.tgammabf16
   libc.src.math.truncbf16
   libc.src.math.totalorderbf16
   libc.src.math.totalordermagbf16
diff --git a/libc/config/gpu/amdgpu/entrypoints.txt b/libc/config/gpu/amdgpu/entrypoints.txt
index ea5dff846499f..17e797e9c7ae2 100644
--- a/libc/config/gpu/amdgpu/entrypoints.txt
+++ b/libc/config/gpu/amdgpu/entrypoints.txt
@@ -713,6 +713,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
   libc.src.math.setpayloadsigbf16
   libc.src.math.sqrtbf16
   libc.src.math.tanbf16
+  libc.src.math.tgammabf16
   libc.src.math.truncbf16
   libc.src.math.totalorderbf16
   libc.src.math.totalordermagbf16
diff --git a/libc/config/gpu/nvptx/entrypoints.txt b/libc/config/gpu/nvptx/entrypoints.txt
index 8ccb39cfd6605..4bff935042427 100644
--- a/libc/config/gpu/nvptx/entrypoints.txt
+++ b/libc/config/gpu/nvptx/entrypoints.txt
@@ -715,6 +715,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
   libc.src.math.setpayloadsigbf16
   libc.src.math.sqrtbf16
   libc.src.math.tanbf16
+  libc.src.math.tgammabf16
   libc.src.math.truncbf16
   libc.src.math.totalorderbf16
   libc.src.math.totalordermagbf16
diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index c4db45ad3c50e..12200581643ca 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -991,6 +991,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
   libc.src.math.setpayloadsigbf16
   libc.src.math.sqrtbf16
   libc.src.math.tanbf16
+  libc.src.math.tgammabf16
   libc.src.math.truncbf16
   libc.src.math.totalorderbf16
   libc.src.math.totalordermagbf16
diff --git a/libc/config/linux/arm/entrypoints.txt b/libc/config/linux/arm/entrypoints.txt
index 20763eec40e8b..556caef00465d 100644
--- a/libc/config/linux/arm/entrypoints.txt
+++ b/libc/config/linux/arm/entrypoints.txt
@@ -568,6 +568,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
   libc.src.math.setpayloadsigbf16
   libc.src.math.sqrtbf16
   libc.src.math.tanbf16
+  libc.src.math.tgammabf16
   libc.src.math.truncbf16
   libc.src.math.totalorderbf16
   libc.src.math.totalordermagbf16
diff --git a/libc/config/linux/riscv/entrypoints.txt b/libc/config/linux/riscv/entrypoints.txt
index bef3bca77df0e..0613f407ec0de 100644
--- a/libc/config/linux/riscv/entrypoints.txt
+++ b/libc/config/linux/riscv/entrypoints.txt
@@ -1012,6 +1012,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
   libc.src.math.setpayloadsigbf16
   libc.src.math.sqrtbf16
   libc.src.math.tanbf16
+  libc.src.math.tgammabf16
   libc.src.math.truncbf16
   libc.src.math.totalorderbf16
   libc.src.math.totalordermagbf16
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index e0bf4ff52d13a..fe902b29db717 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -1083,6 +1083,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
   libc.src.math.setpayloadsigbf16
   libc.src.math.sqrtbf16
   libc.src.math.tanbf16
+  libc.src.math.tgammabf16
   libc.src.math.truncbf16
   libc.src.math.totalorderbf16
   libc.src.math.totalordermagbf16
diff --git a/libc/config/windows/entrypoints.txt b/libc/config/windows/entrypoints.txt
index 5333bc4042070..9a71f82a5dc22 100644
--- a/libc/config/windows/entrypoints.txt
+++ b/libc/config/windows/entrypoints.txt
@@ -395,6 +395,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
   libc.src.math.setpayloadsigbf16
   libc.src.math.sqrtbf16
   libc.src.math.tanbf16
+  libc.src.math.tgammabf16
   libc.src.math.truncbf16
   libc.src.math.totalorderbf16
   libc.src.math.totalordermagbf16
@@ -406,4 +407,3 @@ set(TARGET_LLVMLIBC_ENTRYPOINTS
   ${TARGET_LIBC_ENTRYPOINTS}
   ${TARGET_LIBM_ENTRYPOINTS}
 )
-
diff --git a/libc/shared/math.h b/libc/shared/math.h
index 8e01154c5ab56..edae1d5f77c55 100644
--- a/libc/shared/math.h
+++ b/libc/shared/math.h
@@ -482,6 +482,7 @@
 #include "math/tanhf16.h"
 #include "math/tanpif.h"
 #include "math/tanpif16.h"
+#include "math/tgammabf16.h"
 #include "math/totalorder.h"
 #include "math/totalorderbf16.h"
 #include "math/totalorderf.h"
diff --git a/libc/shared/math/tgammabf16.h b/libc/shared/math/tgammabf16.h
new file mode 100644
index 0000000000000..1d1db83182300
--- /dev/null
+++ b/libc/shared/math/tgammabf16.h
@@ -0,0 +1,23 @@
+//===-- Shared tgammabf16 function ------------------------------*- 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_SHARED_MATH_TGAMMABF16_H
+#define LLVM_LIBC_SHARED_MATH_TGAMMABF16_H
+
+#include "shared/libc_common.h"
+#include "src/__support/math/tgammabf16.h"
+
+namespace LIBC_NAMESPACE_DECL {
+namespace shared {
+
+using math::tgammabf16;
+
+} // namespace shared
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SHARED_MATH_TGAMMABF16_H
diff --git a/libc/src/__support/math/CMakeLists.txt b/libc/src/__support/math/CMakeLists.txt
index deafc85b487a6..a076a4f219992 100644
--- a/libc/src/__support/math/CMakeLists.txt
+++ b/libc/src/__support/math/CMakeLists.txt
@@ -5438,6 +5438,25 @@ add_header_library(
     libc.src.__support.FPUtil.bfloat16
 )
 
+add_header_library(
+  tgammabf16
+  HDRS
+    tgammabf16.h
+  DEPENDS
+    libc.hdr.errno_macros
+    libc.hdr.fenv_macros
+    libc.src.__support.FPUtil.bfloat16
+    libc.src.__support.FPUtil.cast
+    libc.src.__support.FPUtil.fenv_impl
+    libc.src.__support.FPUtil.fp_bits
+    libc.src.__support.FPUtil.multiply_add
+    libc.src.__support.macros.config
+    libc.src.__support.macros.optimization
+    libc.src.__support.math.exp
+    libc.src.__support.math.log
+    libc.src.__support.math.sin
+)
+
 add_header_library(
   tanf
   HDRS
diff --git a/libc/src/__support/math/tgammabf16.h b/libc/src/__support/math/tgammabf16.h
new file mode 100644
index 0000000000000..275f9fc15745b
--- /dev/null
+++ b/libc/src/__support/math/tgammabf16.h
@@ -0,0 +1,179 @@
+//===-- Implementation header for tgammabf16 --------------------*- 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_TGAMMABF16_H
+#define LLVM_LIBC_SRC___SUPPORT_MATH_TGAMMABF16_H
+
+#include "hdr/errno_macros.h"
+#include "hdr/fenv_macros.h"
+#include "src/__support/FPUtil/FEnvImpl.h"
+#include "src/__support/FPUtil/FPBits.h"
+#include "src/__support/FPUtil/bfloat16.h"
+#include "src/__support/FPUtil/cast.h"
+#include "src/__support/FPUtil/multiply_add.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/optimization.h"
+#include "src/__support/math/exp.h"
+#include "src/__support/math/log.h"
+#include "src/__support/math/sin.h"
+
+namespace LIBC_NAMESPACE_DECL {
+namespace math {
+
+namespace tgammabf16_internal {
+
+LIBC_INLINE_VAR constexpr double PI = 0x1.921fb54442d18p+1;
+LIBC_INLINE_VAR constexpr double LOG_SQRT_2_PI = 0x1.d67f1c864beb5p-1;
+
+// Paul Godfrey's exact Lanczos approximation coefficients (g=7, n=9)
+LIBC_INLINE_VAR constexpr double LANCZOS_COEFFS[9] = {
+    0.99999999999980993,  676.5203681218851,     -1259.1392167224028,
+    771.32342877765313,   -176.61502916214059,   12.507343278224757,
+    -0.13857109526572012, 9.9843695780195716e-6, 1.5056327351493116e-7};
+
+LIBC_INLINE bool is_negative_integer(double x) {
+  if (x > -1.0)
+    return false;
+  if (x <= -128.0)
+    return true;
+  int n = static_cast<int>(x);
+  return x == static_cast<double>(n);
+}
+
+} // namespace tgammabf16_internal
+
+LIBC_INLINE bfloat16 tgammabf16(bfloat16 x) {
+  using FPBits = fputil::FPBits<bfloat16>;
+  using namespace tgammabf16_internal;
+
+  FPBits xbits(x);
+
+  if (LIBC_UNLIKELY(xbits.is_nan())) {
+    if (xbits.is_signaling_nan()) {
+      fputil::raise_except_if_required(FE_INVALID);
+      return FPBits::quiet_nan().get_val();
+    }
+    return x;
+  }
+
+  if (LIBC_UNLIKELY(xbits.is_inf())) {
+    if (xbits.is_pos())
+      return x;
+    fputil::set_errno_if_required(EDOM);
+    fputil::raise_except_if_required(FE_INVALID);
+    return FPBits::quiet_nan().get_val();
+  }
+
+  if (LIBC_UNLIKELY(xbits.is_zero())) {
+    fputil::set_errno_if_required(ERANGE);
+    fputil::raise_except_if_required(FE_DIVBYZERO);
+    return FPBits::inf(xbits.sign()).get_val();
+  }
+
+  double xd = static_cast<double>(static_cast<float>(x));
+  if (LIBC_UNLIKELY(is_negative_integer(xd))) {
+    fputil::set_errno_if_required(EDOM);
+    fputil::raise_except_if_required(FE_INVALID);
+    return FPBits::quiet_nan().get_val();
+  }
+
+  // Fast path for exact positive integers
+  if (xd > 0.0 && xd <= 35.0) {
+    int n = static_cast<int>(xd);
+    if (xd == static_cast<double>(n)) {
+      double res = 1.0;
+      for (int i = 1; i < n; ++i)
+        res *= i;
+      return fputil::cast<bfloat16>(res);
+    }
+  }
+
+  bool reflection = false;
+  bool divide_by_x = false;
+  double x_eval = xd;
+  double res;
+
+  // Fast path for tiny positive inputs to prevent exact-boundary overshoots
+  // For tiny x, Gamma(x) ~= 1/x - gamma
+  if (LIBC_UNLIKELY(xd > 0.0 && xd < 0x1.0p-8)) {
+    res = (1.0 / xd) - 0.577215664901532860606;
+  } else {
+    if (xd < 0.0) {
+      reflection = true;
+      x_eval = 1.0 - xd;
+    } else if (xd < 1.0) {
+      divide_by_x = true;
+      x_eval = xd + 1.0;
+    }
+
+    double z = x_eval - 1.0;
+    double a = LANCZOS_COEFFS[0];
+    for (int i = 1; i < 9; ++i) {
+      a += LANCZOS_COEFFS[i] / (z + static_cast<double>(i));
+    }
+
+    double t = z + 7.5;
+
+    // ILP Optimization: FMA for the exponent argument
+    double log_t = math::log(t);
+    double base_term = (LOG_SQRT_2_PI - t) + math::log(a);
+    double exp_arg = fputil::multiply_add(z + 0.5, log_t, base_term);
+
+    res = math::exp(exp_arg);
+
+    if (reflection) {
+      double sin_pi_x = math::sin(PI * xd);
+      double denom = sin_pi_x * res;
+
+      if (LIBC_UNLIKELY(denom == 0.0)) {
+        fputil::set_errno_if_required(ERANGE);
+        fputil::raise_except_if_required(FE_UNDERFLOW);
+        return FPBits::zero(Sign::POS).get_val();
+      }
+      res = PI / denom;
+    } else if (divide_by_x) {
+      res = res / xd;
+    }
+  }
+
+  double abs_res = res < 0.0 ? -res : res;
+
+  // 0x1.ffp127 is max normal + 0.5 ULP in bfloat16, the exact RTN overflow
+  // threshold
+  if (LIBC_UNLIKELY(abs_res > 0x1.ffp+127)) {
+    fputil::set_errno_if_required(ERANGE);
+    fputil::raise_except_if_required(FE_OVERFLOW);
+
+#ifdef LIBC_MATH_HAS_ASSUME_ROUND_NEAREST_ONLY
+    return FPBits::inf(res > 0.0 ? Sign::POS : Sign::NEG).get_val();
+#else
+    Sign sign = res > 0.0 ? Sign::POS : Sign::NEG;
+    switch (fputil::quick_get_round()) {
+    case FE_TONEAREST:
+      return FPBits::inf(sign).get_val();
+    case FE_UPWARD:
+      return sign == Sign::POS ? FPBits::inf(Sign::POS).get_val()
+                               : FPBits::max_normal(Sign::NEG).get_val();
+    case FE_DOWNWARD:
+      return sign == Sign::POS ? FPBits::max_normal(Sign::POS).get_val()
+                               : FPBits::inf(Sign::NEG).get_val();
+    case FE_TOWARDZERO:
+      return FPBits::max_normal(sign).get_val();
+    default:
+      return FPBits::max_normal(sign).get_val();
+    }
+#endif
+  }
+
+  return fputil::cast<bfloat16>(res);
+}
+
+} // namespace math
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_MATH_TGAMMABF16_H
diff --git a/libc/src/math/CMakeLists.txt b/libc/src/math/CMakeLists.txt
index fd768eaed26af..f3e86d9439f4a 100644
--- a/libc/src/math/CMakeLists.txt
+++ b/libc/src/math/CMakeLists.txt
@@ -600,6 +600,7 @@ add_math_entrypoint_object(tanpif)
 add_math_entrypoint_object(tanpif16)
 
 add_math_entrypoint_object(tgamma)
+add_math_entrypoint_object(tgammabf16)
 add_math_entrypoint_object(tgammaf)
 add_math_entrypoint_object(lgamma)
 add_math_entrypoint_object(lgamma_r)
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index 28b708e0c8f7a..64da6c553eb25 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -425,6 +425,16 @@ add_entrypoint_object(
     libc.src.__support.math.tanbf16
 )
 
+add_entrypoint_object(
+  tgammabf16
+  SRCS
+    tgammabf16.cpp
+  HDRS
+    ../tgammabf16.h
+  DEPENDS
+    libc.src.__support.math.tgammabf16
+)
+
 add_entrypoint_object(
   tanf
   SRCS
diff --git a/libc/src/math/generic/tgammabf16.cpp b/libc/src/math/generic/tgammabf16.cpp
new file mode 100644
index 0000000000000..c5772f00c154f
--- /dev/null
+++ b/libc/src/math/generic/tgammabf16.cpp
@@ -0,0 +1,18 @@
+//===-- Implementation of tgammabf16 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/__support/math/tgammabf16.h"
+#include "src/math/tgammabf16.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(bfloat16, tgammabf16, (bfloat16 x)) {
+  return math::tgammabf16(x);
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/math/tgammabf16.h b/libc/src/math/tgammabf16.h
new file mode 100644
index 0000000000000..1aa93bb10c103
--- /dev/null
+++ b/libc/src/math/tgammabf16.h
@@ -0,0 +1,21 @@
+//===-- Implementation header for tgammabf16 --------------------*- 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_TGAMMABF16_H
+#define LLVM_LIBC_SRC_MATH_TGAMMABF16_H
+
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+bfloat16 tgammabf16(bfloat16 x);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_MATH_TGAMMABF16_H
diff --git a/libc/test/shared/CMakeLists.txt b/libc/test/shared/CMakeLists.txt
index 5156e7e5b32d0..1685a9234c055 100644
--- a/libc/test/shared/CMakeLists.txt
+++ b/libc/test/shared/CMakeLists.txt
@@ -487,6 +487,7 @@ add_fp_unittest(
     libc.src.__support.math.tanhf16
     libc.src.__support.math.tanpif
     libc.src.__support.math.tanpif16
+    libc.src.__support.math.tgammabf16
     libc.src.__support.math.trunc
     libc.src.__support.math.truncbf16
     libc.src.__support.math.truncf
diff --git a/libc/test/shared/shared_math_test.cpp b/libc/test/shared/shared_math_test.cpp
index 8ae2aac3d51ed..08c69b19dfbf8 100644
--- a/libc/test/shared/shared_math_test.cpp
+++ b/libc/test/shared/shared_math_test.cpp
@@ -802,6 +802,9 @@ TEST(LlvmLibcSharedMathTest, AllBFloat16) {
                                                          bfloat16(0.0)));
   EXPECT_FP_EQ(bfloat16(0.0), setpayloadsigbf16_res);
 
+  EXPECT_FP_EQ(bfloat16(1.0f),
+               LIBC_NAMESPACE::shared::tgammabf16(bfloat16(1.0f)));
+
   EXPECT_FP_EQ(bfloat16(1.0), LIBC_NAMESPACE::shared::expbf16(bfloat16(0.0)));
   EXPECT_FP_EQ(bfloat16(0.0), LIBC_NAMESPACE::shared::log_bf16(bfloat16(1.0)));
 
diff --git a/libc/test/src/math/CMakeLists.txt b/libc/test/src/math/CMakeLists.txt
index 4698f246fe4cc..d33158f037fd8 100644
--- a/libc/test/src/math/CMakeLists.txt
+++ b/libc/test/src/math/CMakeLists.txt
@@ -3193,6 +3193,18 @@ add_fp_unittest(
     libc.src.__support.FPUtil.bfloat16
 )
 
+add_fp_unittest(
+  tgammabf16_test
+  NEED_MPFR
+  SUITE
+    libc-math-unittests
+  SRCS
+    tgammabf16_test.cpp
+  DEPENDS
+    libc.src.math.tgammabf16
+    libc.src.__support.FPUtil.bfloat16
+)
+
 add_fp_unittest(
   dmull_test
   NEED_MPFR
diff --git a/libc/test/src/math/smoke/CMakeLists.txt b/libc/test/src/math/smoke/CMakeLists.txt
index e4e2fb11438d4..820425cc13161 100644
--- a/libc/test/src/math/smoke/CMakeLists.txt
+++ b/libc/test/src/math/smoke/CMakeLists.txt
@@ -6229,6 +6229,19 @@ add_fp_unittest(
     libc.src.__support.FPUtil.bfloat16
 )
 
+add_fp_unittest(
+  tgammabf16_test
+  SUITE
+    libc-math-smoke-tests
+  SRCS
+    tgammabf16_test.cpp
+  DEPENDS
+    libc.hdr.errno_macros
+    libc.hdr.fenv_macros
+    libc.src.math.tgammabf16
+    libc.src.__support.FPUtil.bfloat16
+)
+
 add_fp_unittest(
   dmull_test
   SUITE
diff --git a/libc/test/src/math/smoke/tgammabf16_test.cpp b/libc/test/src/math/smoke/tgammabf16_test.cpp
new file mode 100644
index 0000000000000..d6f1223c5214c
--- /dev/null
+++ b/libc/test/src/math/smoke/tgammabf16_test.cpp
@@ -0,0 +1,79 @@
+//===-- Unittests for tgammabf16 ------------------------------------------===//
+//
+// 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 "hdr/errno_macros.h"
+#include "hdr/fenv_macros.h"
+#include "src/__support/FPUtil/bfloat16.h"
+#include "src/math/tgammabf16.h"
+#include "test/UnitTest/FEnvSafeTest.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+
+class LlvmLibcTgammaBf16Test : public LIBC_NAMESPACE::testing::FEnvSafeTest {
+  DECLARE_SPECIAL_CONSTANTS(bfloat16)
+
+public:
+  void test_special_numbers() {
+    EXPECT_FP_EQ_ALL_ROUNDING(aNaN, LIBC_NAMESPACE::tgammabf16(aNaN));
+    EXPECT_MATH_ERRNO(0);
+
+    EXPECT_FP_EQ_WITH_EXCEPTION(aNaN, LIBC_NAMESPACE::tgammabf16(sNaN),
+                                FE_INVALID);
+    EXPECT_MATH_ERRNO(0);
+
+    EXPECT_FP_EQ_ALL_ROUNDING(inf, LIBC_NAMESPACE::tgammabf16(inf));
+    EXPECT_MATH_ERRNO(0);
+
+    EXPECT_FP_EQ_WITH_EXCEPTION_ALL_ROUNDING(
+        aNaN, LIBC_NAMESPACE::tgammabf16(neg_inf), FE_INVALID);
+    EXPECT_MATH_ERRNO(EDOM);
+
+    EXPECT_FP_EQ_WITH_EXCEPTION_ALL_ROUNDING(
+        inf, LIBC_NAMESPACE::tgammabf16(zero), FE_DIVBYZERO);
+    EXPECT_MATH_ERRNO(ERANGE);
+
+    EXPECT_FP_EQ_WITH_EXCEPTION_ALL_ROUNDING(
+        neg_inf, LIBC_NAMESPACE::tgammabf16(neg_zero), FE_DIVBYZERO);
+    EXPECT_MATH_ERRNO(ERANGE);
+  }
+
+  void test_poles() {
+    EXPECT_FP_EQ_WITH_EXCEPTION_ALL_ROUNDING(
+        aNaN, LIBC_NAMESPACE::tgammabf16(bfloat16(-1.0f)), FE_INVALID);
+    EXPECT_MATH_ERRNO(EDOM);
+
+    EXPECT_FP_EQ_WITH_EXCEPTION_ALL_ROUNDING(
+        aNaN, LIBC_NAMESPACE::tgammabf16(bfloat16(-2.0f)), FE_INVALID);
+    EXPECT_MATH_ERRNO(EDOM);
+  }
+
+  void test_values() {
+    EXPECT_FP_EQ_ALL_ROUNDING(bfloat16(1.0f),
+                              LIBC_NAMESPACE::tgammabf16(bfloat16(1.0f)));
+    EXPECT_FP_EQ_ALL_ROUNDING(bfloat16(1.0f),
+                              LIBC_NAMESPACE::tgammabf16(bfloat16(2.0f)));
+    EXPECT_FP_EQ_ALL_ROUNDING(bfloat16(2.0f),
+                              LIBC_NAMESPACE::tgammabf16(bfloat16(3.0f)));
+    EXPECT_FP_EQ_ALL_ROUNDING(bfloat16(24.0f),
+                              LIBC_NAMESPACE::tgammabf16(bfloat16(5.0f)));
+  }
+
+  void test_boundaries() {
+    EXPECT_FP_EQ_ALL_ROUNDING(bfloat16(2.951479e38f),
+                              LIBC_NAMESPACE::tgammabf16(bfloat16(35.0f)));
+
+    EXPECT_FP_EQ_WITH_EXCEPTION(
+        inf, LIBC_NAMESPACE::tgammabf16(bfloat16(36.0f)), FE_OVERFLOW);
+    EXPECT_MATH_ERRNO(ERANGE);
+  }
+};
+
+TEST_F(LlvmLibcTgammaBf16Test, SpecialNumbers) { test_special_numbers(); }
+TEST_F(LlvmLibcTgammaBf16Test, Poles) { test_poles(); }
+TEST_F(LlvmLibcTgammaBf16Test, Values) { test_values(); }
+TEST_F(LlvmLibcTgammaBf16Test, Boundaries) { test_boundaries(); }
diff --git a/libc/test/src/math/tgammabf16_test.cpp b/libc/test/src/math/tgammabf16_test.cpp
new file mode 100644
index 0000000000000..5d4087ccc85c5
--- /dev/null
+++ b/libc/test/src/math/tgammabf16_test.cpp
@@ -0,0 +1,42 @@
+//===-- Exhaustive test for tgammabf16 ------------------------------------===//
+//
+// 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/tgammabf16.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+#include "utils/MPFRWrapper/MPFRUtils.h"
+
+using LlvmLibcTgammaBf16Test = LIBC_NAMESPACE::testing::FPTest<bfloat16>;
+
+namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
+
+static bool is_negative_integer(bfloat16 x) {
+  float xf = static_cast<float>(x);
+  if (xf > -1.0f)
+    return false;
+  if (xf <= -128.0f)
+    return true;
+  int n = static_cast<int>(xf);
+  return xf == static_cast<float>(n);
+}
+
+TEST_F(LlvmLibcTgammaBf16Test, Exhaustive) {
+  for (uint32_t v = 0x0000; v < 0x10000; ++v) {
+    bfloat16 x =
+        LIBC_NAMESPACE::fputil::FPBits<bfloat16>(static_cast<uint16_t>(v))
+            .get_val();
+    LIBC_NAMESPACE::fputil::FPBits<bfloat16> bits(x);
+
+    if (bits.is_nan() || bits.is_zero() ||
+        (bits.is_neg() && is_negative_integer(x)))
+      continue;
+    EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Tgamma, x,
+                                   LIBC_NAMESPACE::tgammabf16(x), 1.0);
+  }
+}
diff --git a/libc/utils/MPFRWrapper/MPCommon.cpp b/libc/utils/MPFRWrapper/MPCommon.cpp
index 452a1391058d4..b5ca8370848e2 100644
--- a/libc/utils/MPFRWrapper/MPCommon.cpp
+++ b/libc/utils/MPFRWrapper/MPCommon.cpp
@@ -529,6 +529,12 @@ MPFRNumber MPFRNumber::tanh() const {
   return result;
 }
 
+MPFRNumber MPFRNumber::tgamma() const {
+  MPFRNumber result(*this);
+  mpfr_gamma(result.value, value, mpfr_rounding);
+  return result;
+}
+
 MPFRNumber MPFRNumber::tanpi() const {
   MPFRNumber result(*this);
 
diff --git a/libc/utils/MPFRWrapper/MPCommon.h b/libc/utils/MPFRWrapper/MPCommon.h
index 935a2614968a2..96149487170a5 100644
--- a/libc/utils/MPFRWrapper/MPCommon.h
+++ b/libc/utils/MPFRWrapper/MPCommon.h
@@ -237,6 +237,7 @@ class MPFRNumber {
   MPFRNumber tan() const;
   MPFRNumber tanh() const;
   MPFRNumber tanpi() const;
+  MPFRNumber tgamma() const;
   MPFRNumber trunc() const;
   MPFRNumber fma(const MPFRNumber &b, const MPFRNumber &c);
   MPFRNumber mul(const MPFRNumber &b);
diff --git a/libc/utils/MPFRWrapper/MPFRUtils.cpp b/libc/utils/MPFRWrapper/MPFRUtils.cpp
index 356764302bda8..2fadaf4bc8388 100644
--- a/libc/utils/MPFRWrapper/MPFRUtils.cpp
+++ b/libc/utils/MPFRWrapper/MPFRUtils.cpp
@@ -113,6 +113,8 @@ unary_operation(Operation op, InputType input, unsigned int precision,
     return mpfrInput.tanh();
   case Operation::Tanpi:
     return mpfrInput.tanpi();
+  case Operation::Tgamma:
+    return mpfrInput.tgamma();
   case Operation::Trunc:
     return mpfrInput.trunc();
   default:
diff --git a/libc/utils/MPFRWrapper/MPFRUtils.h b/libc/utils/MPFRWrapper/MPFRUtils.h
index 64343fde2969f..3383d2d2434c9 100644
--- a/libc/utils/MPFRWrapper/MPFRUtils.h
+++ b/libc/utils/MPFRWrapper/MPFRUtils.h
@@ -67,6 +67,7 @@ enum class Operation : int {
   Tan,
   Tanh,
   Tanpi,
+  Tgamma,
   Trunc,
   EndUnaryOperationsSingleOutput,
 
diff --git a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
index 56ef8876c9e2d..a1bd87e143979 100644
--- a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
+++ b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
@@ -9267,6 +9267,25 @@ libc_support_library(
     ],
 )
 
+libc_support_library(
+    name = "__support_math_tgammabf16",
+    hdrs = ["src/__support/math/tgammabf16.h"],
+    deps = [
+        ":__support_fputil_bfloat16",
+        ":__support_fputil_cast",
+        ":__support_fputil_fenv_impl",
+        ":__support_fputil_fp_bits",
+        ":__support_fputil_multiply_add",
+        ":__support_macros_config",
+        ":__support_macros_optimization",
+        ":__support_math_exp",
+        ":__support_math_log",
+        ":__support_math_sin",
+        ":hdr_errno_macros",
+        ":hdr_fenv_macros",
+    ],
+)
+
 libc_support_library(
     name = "__support_math_totalorder",
     hdrs = ["src/__support/math/totalorder.h"],
@@ -12972,6 +12991,13 @@ libc_math_function(
     additional_deps = [":__support_math_tanpif16"],
 )
 
+libc_math_function(
+    name = "tgammabf16",
+    additional_deps = [
+        ":__support_math_tgammabf16",
+    ],
+)
+
 libc_math_function(
     name = "totalorder",
     additional_deps = [



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