[libc] [llvm] [libc][math] change bf16fmal to be header-only and constexpr-compat (PR #181666)

via llvm-commits llvm-commits at lists.llvm.org
Wed Feb 18 05:09:13 PST 2026 

https://github.com/Serosh-commits updated https://github.com/llvm/llvm-project/pull/181666

>From e072f012cf859e0b9827fd1e27e040b4e42ab44a Mon Sep 17 00:00:00 2001
From: Serosh-commits <janmejayapanda400 at gmail.com>
Date: Mon, 16 Feb 2026 19:13:42 +0530
Subject: [PATCH] addressed reviewer feedback

---
 libc/shared/math.h                            |  1 +
 libc/shared/math/bf16fmal.h                   | 25 ++++++++++++++++++
 libc/src/__support/math/CMakeLists.txt        | 10 +++++++
 libc/src/__support/math/bf16fmal.h            | 26 +++++++++++++++++++
 libc/src/math/generic/CMakeLists.txt          |  6 +----
 libc/src/math/generic/bf16fmal.cpp            |  9 +++----
 libc/test/shared/CMakeLists.txt               |  1 +
 libc/test/shared/shared_math_test.cpp         |  2 ++
 .../llvm-project-overlay/libc/BUILD.bazel     | 18 +++++++++++++
 9 files changed, 87 insertions(+), 11 deletions(-)
 create mode 100644 libc/shared/math/bf16fmal.h
 create mode 100644 libc/src/__support/math/bf16fmal.h

diff --git a/libc/shared/math.h b/libc/shared/math.h
index 828980a3500df..89b9f78bec2b2 100644
--- a/libc/shared/math.h
+++ b/libc/shared/math.h
@@ -35,6 +35,7 @@
 #include "math/bf16addf128.h"
 #include "math/bf16divf.h"
 #include "math/bf16fmaf.h"
+#include "math/bf16fmal.h"
 #include "math/canonicalize.h"
 #include "math/canonicalizebf16.h"
 #include "math/canonicalizef.h"
diff --git a/libc/shared/math/bf16fmal.h b/libc/shared/math/bf16fmal.h
new file mode 100644
index 0000000000000..24aacc53c72a8
--- /dev/null
+++ b/libc/shared/math/bf16fmal.h
@@ -0,0 +1,25 @@
+//===-- Shared bf16fmal 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_BF16FMAL_H
+#define LLVM_LIBC_SHARED_MATH_BF16FMAL_H
+
+#include "shared/libc_common.h"
+#include "src/__support/math/bf16fmal.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+namespace shared {
+
+using math::bf16fmal;
+
+} // namespace shared
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SHARED_MATH_BF16FMAL_H
diff --git a/libc/src/__support/math/CMakeLists.txt b/libc/src/__support/math/CMakeLists.txt
index af2c66597b75a..c8b75425389bc 100644
--- a/libc/src/__support/math/CMakeLists.txt
+++ b/libc/src/__support/math/CMakeLists.txt
@@ -845,6 +845,16 @@ add_header_library(
     libc.include.llvm-libc-macros.float16_macros
 )
 
+add_header_library(
+  bf16fmal
+  HDRS
+    bf16fmal.h
+  DEPENDS
+    libc.src.__support.macros.config
+    libc.src.__support.FPUtil.fma
+    libc.src.__support.FPUtil.bfloat16
+)
+
 add_header_library(
   ilogb
   HDRS
diff --git a/libc/src/__support/math/bf16fmal.h b/libc/src/__support/math/bf16fmal.h
new file mode 100644
index 0000000000000..93a04d0ec8fac
--- /dev/null
+++ b/libc/src/__support/math/bf16fmal.h
@@ -0,0 +1,26 @@
+//===-- Implementation header for bf16fmal ----------------------*- 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_BF16FMAL_H
+#define LLVM_LIBC_SRC___SUPPORT_MATH_BF16FMAL_H
+
+#include "src/__support/FPUtil/FMA.h"
+#include "src/__support/FPUtil/bfloat16.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+namespace math {
+
+LIBC_INLINE bfloat16 bf16fmal(long double x, long double y, long double z) {
+  return fputil::fma<bfloat16>(x, y, z);
+}
+
+} // namespace math
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_MATH_BF16FMAL_H
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index 47101706ce4c8..886c790b8e27a 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -5241,11 +5241,7 @@ add_entrypoint_object(
   HDRS
     ../bf16fmal.h
   DEPENDS
-    libc.src.__support.common
-    libc.src.__support.FPUtil.bfloat16
-    libc.src.__support.FPUtil.fma
-    libc.src.__support.macros.config
-    libc.src.__support.macros.properties.types
+    libc.src.__support.math.bf16fmal
 )
 
 add_entrypoint_object(
diff --git a/libc/src/math/generic/bf16fmal.cpp b/libc/src/math/generic/bf16fmal.cpp
index f31ec6904760b..0e8f1901c2093 100644
--- a/libc/src/math/generic/bf16fmal.cpp
+++ b/libc/src/math/generic/bf16fmal.cpp
@@ -7,16 +7,13 @@
 //===----------------------------------------------------------------------===//
 
 #include "src/math/bf16fmal.h"
-
-#include "src/__support/FPUtil/FMA.h"
-#include "src/__support/FPUtil/bfloat16.h"
-#include "src/__support/common.h"
-#include "src/__support/macros/config.h"
+#include "src/__support/math/bf16fmal.h"
 
 namespace LIBC_NAMESPACE_DECL {
 
 LLVM_LIBC_FUNCTION(bfloat16, bf16fmal,
                    (long double x, long double y, long double z)) {
-  return fputil::fma<bfloat16>(x, y, z);
+  return math::bf16fmal(x, y, z);
 }
+
 } // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/test/shared/CMakeLists.txt b/libc/test/shared/CMakeLists.txt
index dfe2378269921..89719a995a13d 100644
--- a/libc/test/shared/CMakeLists.txt
+++ b/libc/test/shared/CMakeLists.txt
@@ -31,6 +31,7 @@ add_fp_unittest(
     libc.src.__support.math.bf16addf128
     libc.src.__support.math.bf16divf
     libc.src.__support.math.bf16fmaf
+    libc.src.__support.math.bf16fmal
     libc.src.__support.math.canonicalize
     libc.src.__support.math.canonicalizebf16
     libc.src.__support.math.canonicalizef
diff --git a/libc/test/shared/shared_math_test.cpp b/libc/test/shared/shared_math_test.cpp
index 8eba836538c41..70345ad2e5cfe 100644
--- a/libc/test/shared/shared_math_test.cpp
+++ b/libc/test/shared/shared_math_test.cpp
@@ -236,6 +236,8 @@ TEST(LlvmLibcSharedMathTest, AllFloat128) {
 TEST(LlvmLibcSharedMathTest, AllBFloat16) {
   EXPECT_FP_EQ(bfloat16(5.0), LIBC_NAMESPACE::shared::bf16add(2.0, 3.0));
   EXPECT_FP_EQ(bfloat16(2.0f), LIBC_NAMESPACE::shared::bf16divf(4.0f, 2.0f));
+  EXPECT_FP_EQ(bfloat16(10.0),
+               LIBC_NAMESPACE::shared::bf16fmal(2.0L, 3.0L, 4.0L));
 
   bfloat16 canonicalizebf16_cx = bfloat16(0.0);
   bfloat16 canonicalizebf16_x = bfloat16(0.0);
diff --git a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
index a5b6823b9ca3d..e5c3a5b6da429 100644
--- a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
+++ b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
@@ -3036,6 +3036,17 @@ libc_support_library(
     ],
 )
 
+libc_support_library(
+    name = "__support_math_bf16fmal",
+    hdrs = ["src/__support/math/bf16fmal.h"],
+    deps = [
+        ":__support_common",
+        ":__support_fputil_fma",
+        ":__support_fputil_bfloat16",
+        ":__support_macros_config",
+    ],
+)
+
 libc_support_library(
     name = "__support_math_ffma",
     hdrs = ["src/__support/math/ffma.h"],
@@ -4793,6 +4804,13 @@ libc_math_function(
     additional_deps = [":__support_math_f16fmal"],
 )
 
+libc_math_function(
+    name = "bf16fmal",
+    additional_deps = [
+        ":__support_math_bf16fmal",
+    ],
+)
+
 libc_math_function(name = "f16mul")
 
 libc_math_function(name = "f16mulf")

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