[libc][math][c++23] Add sqrtbf16 math function (#156654)

krishna2803 · web-flow · commit 8dda18f83611 · 2025-09-06T14:36:02.000+05:30
This PR adds sqrtbf16 higher math function for BFloat16 type along with
the tests.

---------

Signed-off-by: Krishna Pandey &lt;kpandey81930@gmail.com&gt;
diff --git a/libc/config/baremetal/aarch64/entrypoints.txt b/libc/config/baremetal/aarch64/entrypoints.txt
@@ -822,6 +822,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
   libc.src.math.scalbnbf16
   libc.src.math.setpayloadbf16
   libc.src.math.setpayloadsigbf16
+  libc.src.math.sqrtbf16
   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
@@ -822,6 +822,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
   libc.src.math.scalbnbf16
   libc.src.math.setpayloadbf16
   libc.src.math.setpayloadsigbf16
+  libc.src.math.sqrtbf16
   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
@@ -822,6 +822,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
   libc.src.math.scalbnbf16
   libc.src.math.setpayloadbf16
   libc.src.math.setpayloadsigbf16
+  libc.src.math.sqrtbf16
   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
@@ -652,6 +652,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
   libc.src.math.scalbnbf16
   libc.src.math.setpayloadbf16
   libc.src.math.setpayloadsigbf16
+  libc.src.math.sqrtbf16
   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
@@ -295,6 +295,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
   libc.src.math.scalbnbf16
   libc.src.math.setpayloadbf16
   libc.src.math.setpayloadsigbf16
+  libc.src.math.sqrtbf16
   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
@@ -678,6 +678,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
   libc.src.math.scalbnbf16
   libc.src.math.setpayloadbf16
   libc.src.math.setpayloadsigbf16
+  libc.src.math.sqrtbf16
   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
@@ -680,6 +680,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
   libc.src.math.scalbnbf16
   libc.src.math.setpayloadbf16
   libc.src.math.setpayloadsigbf16
+  libc.src.math.sqrtbf16
   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
@@ -907,6 +907,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
   libc.src.math.scalbnbf16
   libc.src.math.setpayloadbf16
   libc.src.math.setpayloadsigbf16
+  libc.src.math.sqrtbf16
   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
@@ -522,6 +522,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
   libc.src.math.scalbnbf16
   libc.src.math.setpayloadbf16
   libc.src.math.setpayloadsigbf16
+  libc.src.math.sqrtbf16
   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
@@ -925,6 +925,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
   libc.src.math.scalbnbf16
   libc.src.math.setpayloadbf16
   libc.src.math.setpayloadsigbf16
+  libc.src.math.sqrtbf16
   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
@@ -960,6 +960,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
   libc.src.math.scalbnbf16
   libc.src.math.setpayloadbf16
   libc.src.math.setpayloadsigbf16
+  libc.src.math.sqrtbf16
   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
@@ -368,6 +368,7 @@ list(APPEND TARGET_LIBM_ENTRYPOINTS
   libc.src.math.scalbnbf16
   libc.src.math.setpayloadbf16
   libc.src.math.setpayloadsigbf16
+  libc.src.math.sqrtbf16
   libc.src.math.truncbf16
   libc.src.math.totalorderbf16
   libc.src.math.totalordermagbf16
diff --git a/libc/docs/headers/math/index.rst b/libc/docs/headers/math/index.rst
diff --git a/libc/src/math/CMakeLists.txt b/libc/src/math/CMakeLists.txt
@@ -562,6 +562,7 @@ add_math_entrypoint_object(sqrtf)
 add_math_entrypoint_object(sqrtl)
 add_math_entrypoint_object(sqrtf16)
 add_math_entrypoint_object(sqrtf128)
+add_math_entrypoint_object(sqrtbf16)
 
 add_math_entrypoint_object(tan)
 add_math_entrypoint_object(tanf)
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
@@ -3255,7 +3255,21 @@ add_entrypoint_object(
     libc.src.__support.macros.optimization
     libc.src.__support.macros.properties.types
     libc.src.__support.FPUtil.sqrt
-  )
+)
+
+add_entrypoint_object(
+  sqrtbf16
+  SRCS
+    sqrtbf16.cpp
+  HDRS
+    ../sqrtbf16.h
+  DEPENDS
+    libc.src.__support.common
+    libc.src.__support.FPUtil.bfloat16
+    libc.src.__support.FPUtil.sqrt
+    libc.src.__support.macros.config
+    libc.src.__support.macros.properties.types
+)
 
 add_entrypoint_object(
   remquof
diff --git a/libc/src/math/generic/sqrtbf16.cpp b/libc/src/math/generic/sqrtbf16.cpp
@@ -0,0 +1,21 @@
+//===-- Implementation of sqrtbf16 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/sqrtbf16.h"
+#include "src/__support/FPUtil/bfloat16.h"
+#include "src/__support/FPUtil/sqrt.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(bfloat16, sqrtbf16, (bfloat16 x)) {
+  return fputil::sqrt<bfloat16>(x);
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/math/sqrtbf16.h b/libc/src/math/sqrtbf16.h
@@ -0,0 +1,21 @@
+//===-- Implementation header for sqrtbf16 ----------------------*- 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_SQRTBF16_H
+#define LLVM_LIBC_SRC_MATH_SQRTBF16_H
+
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+bfloat16 sqrtbf16(bfloat16 x);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_MATH_SQRTBF16_H
diff --git a/libc/test/src/math/CMakeLists.txt b/libc/test/src/math/CMakeLists.txt
@@ -1705,6 +1705,18 @@ add_fp_unittest(
     libc.src.math.sqrtf128
 )
 
+add_fp_unittest(
+  sqrtbf16_test
+  NEED_MPFR
+  SUITE
+    libc-math-unittests
+  SRCS
+    sqrtbf16_test.cpp
+  DEPENDS
+    libc.src.math.sqrtbf16
+    libc.src.__support.FPUtil.bfloat16
+)
+
 add_fp_unittest(
   generic_sqrtf_test
   NEED_MPFR
diff --git a/libc/test/src/math/smoke/CMakeLists.txt b/libc/test/src/math/smoke/CMakeLists.txt
@@ -3527,6 +3527,19 @@ add_fp_unittest(
     libc.src.math.sqrtf128
 )
 
+add_fp_unittest(
+  sqrtbf16_test
+  SUITE
+    libc-math-smoke-tests
+  SRCS
+    sqrtbf16_test.cpp
+  HDRS
+    SqrtTest.h
+  DEPENDS
+    libc.src.math.sqrtbf16
+    libc.src.__support.FPUtil.bfloat16
+)
+
 add_fp_unittest(
   generic_sqrtf_test
   SUITE
diff --git a/libc/test/src/math/smoke/sqrtbf16_test.cpp b/libc/test/src/math/smoke/sqrtbf16_test.cpp
@@ -0,0 +1,14 @@
+//===-- Unittests for sqrtbf16 --------------------------------------------===//
+//
+// 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 "SqrtTest.h"
+
+#include "src/__support/FPUtil/bfloat16.h"
+#include "src/math/sqrtbf16.h"
+
+LIST_SQRT_TESTS(bfloat16, LIBC_NAMESPACE::sqrtbf16);
diff --git a/libc/test/src/math/sqrtbf16_test.cpp b/libc/test/src/math/sqrtbf16_test.cpp
@@ -0,0 +1,29 @@
+//===-- Exhaustive test for sqrtbf16 --------------------------------------===//
+//
+// 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/sqrtbf16.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+#include "utils/MPFRWrapper/MPFRUtils.h"
+
+using LlvmLibcSqrtf16Test = LIBC_NAMESPACE::testing::FPTest<bfloat16>;
+
+namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
+
+// range: [0, inf]
+static constexpr uint16_t POS_START = 0x0000U;
+static constexpr uint16_t POS_STOP = 0x7f80U;
+
+TEST_F(LlvmLibcSqrtf16Test, PositiveRange) {
+  for (uint16_t v = POS_START; v <= POS_STOP; ++v) {
+    bfloat16 x = FPBits(v).get_val();
+    EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Sqrt, x,
+                                   LIBC_NAMESPACE::sqrtbf16(x), 0.5);
+  }
+}
diff --git a/libc/utils/MPFRWrapper/MPFRUtils.cpp b/libc/utils/MPFRWrapper/MPFRUtils.cpp
@@ -274,6 +274,10 @@ template void explain_unary_operation_single_output_error(Operation op,
                                                           double, RoundingMode);
 #endif // LIBC_TYPES_FLOAT128_IS_NOT_LONG_DOUBLE
 
+template void explain_unary_operation_single_output_error(Operation op,
+                                                          bfloat16, bfloat16,
+                                                          double, RoundingMode);
+
 template <typename T>
 void explain_unary_operation_two_outputs_error(
     Operation op, T input, const BinaryOutput<T> &libc_result,
@@ -561,6 +565,9 @@ template bool compare_unary_operation_single_output(Operation, float128,
                                                     long double, double,
                                                     RoundingMode);
 #endif // LIBC_TYPES_FLOAT128_IS_NOT_LONG_DOUBLE
+template bool compare_unary_operation_single_output(Operation, bfloat16,
+                                                    bfloat16, double,
+                                                    RoundingMode);
 
 template <typename T>
 bool compare_unary_operation_two_outputs(Operation op, T input,
