[libc-commits] [libc] [llvm] [libc][math][c23] Add rsqrtf() function (PR #159615)

Anton Shepelev via libc-commits libc-commits at lists.llvm.org
Wed Sep 24 13:57:58 PDT 2025


https://github.com/amemov updated https://github.com/llvm/llvm-project/pull/159615

>From e84a1e6fe073929c6bc97bbb673ba90e7b9c79b4 Mon Sep 17 00:00:00 2001
From: Anton Shepelev <shepelev777 at gmail.com>
Date: Thu, 18 Sep 2025 10:42:53 -0700
Subject: [PATCH 1/6] - Initial implementation of rsqrt for single precision
 float

Some small unrelated changes to this PR:
- Added extra - to the top comments to make it look nicer in libc/shared/math/rsqrtf16.h
- Put rsqrtf16 inside of libc/src/__support/math/CMakeLists.txt in sorted order
- Rearanged libc_math_function rsqrtf16 in Bazel to match alphabetical order
---
 libc/config/linux/aarch64/entrypoints.txt     |  1 +
 libc/config/linux/riscv/entrypoints.txt       |  1 +
 libc/config/linux/x86_64/entrypoints.txt      |  1 +
 libc/docs/headers/math/index.rst              |  2 +-
 libc/include/math.yaml                        |  6 +++
 libc/shared/math.h                            |  2 +-
 libc/shared/math/rsqrtf.h                     | 23 ++++++++++
 libc/shared/math/rsqrtf16.h                   |  2 +-
 libc/src/__support/math/CMakeLists.txt        | 46 ++++++++++++-------
 libc/src/math/CMakeLists.txt                  |  1 +
 libc/src/math/generic/CMakeLists.txt          | 11 +++++
 libc/src/math/generic/rsqrtf.cpp              | 15 ++++++
 libc/src/math/rsqrtf.h                        | 20 ++++++++
 libc/test/shared/CMakeLists.txt               |  2 +-
 libc/test/shared/shared_math_test.cpp         |  1 +
 libc/test/src/math/CMakeLists.txt             | 11 +++++
 libc/test/src/math/rsqrtf_test.cpp            | 41 +++++++++++++++++
 libc/test/src/math/smoke/CMakeLists.txt       | 11 +++++
 libc/test/src/math/smoke/rsqrtf_test.cpp      | 42 +++++++++++++++++
 .../llvm-project-overlay/libc/BUILD.bazel     | 38 +++++++++++----
 20 files changed, 249 insertions(+), 28 deletions(-)
 create mode 100644 libc/shared/math/rsqrtf.h
 create mode 100644 libc/src/math/generic/rsqrtf.cpp
 create mode 100644 libc/src/math/rsqrtf.h
 create mode 100644 libc/test/src/math/rsqrtf_test.cpp
 create mode 100644 libc/test/src/math/smoke/rsqrtf_test.cpp

diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index 00c4b2ec0f828..9e04eedd16162 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -735,6 +735,7 @@ if(LIBC_TYPES_HAS_FLOAT16)
     libc.src.math.rintf16
     libc.src.math.roundevenf16
     libc.src.math.roundf16
+    libc.src.math.rsqrtf
     libc.src.math.rsqrtf16
     libc.src.math.scalblnf16
     libc.src.math.scalbnf16
diff --git a/libc/config/linux/riscv/entrypoints.txt b/libc/config/linux/riscv/entrypoints.txt
index 89e3653186d13..f5742faf5355e 100644
--- a/libc/config/linux/riscv/entrypoints.txt
+++ b/libc/config/linux/riscv/entrypoints.txt
@@ -749,6 +749,7 @@ if(LIBC_TYPES_HAS_FLOAT16)
     libc.src.math.rintf16
     libc.src.math.roundevenf16
     libc.src.math.roundf16
+    libc.src.math.rsqrtf
     libc.src.math.rsqrtf16
     libc.src.math.scalblnf16
     libc.src.math.scalbnf16
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 0bb8a683c5b01..0b861c537df9e 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -784,6 +784,7 @@ if(LIBC_TYPES_HAS_FLOAT16)
     libc.src.math.rintf16
     libc.src.math.roundevenf16
     libc.src.math.roundf16
+    libc.src.math.rsqrtf
     libc.src.math.rsqrtf16
     libc.src.math.scalblnf16
     libc.src.math.scalbnf16
diff --git a/libc/docs/headers/math/index.rst b/libc/docs/headers/math/index.rst
index 7d5b341ba674a..392b419b2d949 100644
--- a/libc/docs/headers/math/index.rst
+++ b/libc/docs/headers/math/index.rst
@@ -343,7 +343,7 @@ Higher Math Functions
 +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+------------------------+----------------------------+
 | rootn     |                  |                 |                        |                      |                        |                        | 7.12.7.8               | F.10.4.8                   |
 +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+------------------------+----------------------------+
-| rsqrt     |                  |                 |                        | |check|              |                        |                        | 7.12.7.9               | F.10.4.9                   |
+| rsqrt     | |check|          |                 |                        | |check|              |                        |                        | 7.12.7.9               | F.10.4.9                   |
 +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+------------------------+----------------------------+
 | sin       | |check|          | |check|         |                        | |check|              |                        |                        | 7.12.4.6               | F.10.1.6                   |
 +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+------------------------+----------------------------+
diff --git a/libc/include/math.yaml b/libc/include/math.yaml
index 6c800a0e2aa28..afd3ae33305c1 100644
--- a/libc/include/math.yaml
+++ b/libc/include/math.yaml
@@ -2349,6 +2349,12 @@ functions:
     return_type: long double
     arguments:
       - type: long double
+  - name: rsqrtf
+    standards:
+      - stdc
+    return_type: float
+    arguments:
+      - type: float
   - name: rsqrtf16
     standards:
       - stdc
diff --git a/libc/shared/math.h b/libc/shared/math.h
index 4f20095912bf1..abcea786a28b5 100644
--- a/libc/shared/math.h
+++ b/libc/shared/math.h
@@ -52,7 +52,7 @@
 #include "math/ldexpf.h"
 #include "math/ldexpf128.h"
 #include "math/ldexpf16.h"
-
+#include "math/rsqrtf.h"
 #include "math/rsqrtf16.h"
 
 #endif // LLVM_LIBC_SHARED_MATH_H
diff --git a/libc/shared/math/rsqrtf.h b/libc/shared/math/rsqrtf.h
new file mode 100644
index 0000000000000..32d0a61f7c21b
--- /dev/null
+++ b/libc/shared/math/rsqrtf.h
@@ -0,0 +1,23 @@
+//===-- Shared rsqrtf 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_RSQRTF_H
+#define LLVM_LIBC_SHARED_MATH_RSQRTF_H
+
+#include "shared/libc_common.h"
+#include "src/__support/math/rsqrtf.h"
+
+namespace LIBC_NAMESPACE_DECL {
+namespace shared {
+
+using math::rsqrtf;
+
+} // namespace shared
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SHARED_MATH_RSQRTF_H
diff --git a/libc/shared/math/rsqrtf16.h b/libc/shared/math/rsqrtf16.h
index 54c7499214636..8dbf065802f49 100644
--- a/libc/shared/math/rsqrtf16.h
+++ b/libc/shared/math/rsqrtf16.h
@@ -1,4 +1,4 @@
-//===-- Shared rsqrtf16 function -------------------------------*- C++ -*-===//
+//===-- Shared rsqrtf16 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.
diff --git a/libc/src/__support/math/CMakeLists.txt b/libc/src/__support/math/CMakeLists.txt
index ed5f314b0a9b5..26ad5a1d8901a 100644
--- a/libc/src/__support/math/CMakeLists.txt
+++ b/libc/src/__support/math/CMakeLists.txt
@@ -109,22 +109,6 @@ add_header_library(
     libc.src.__support.macros.properties.types
 )
 
-
-add_header_library(
-  rsqrtf16
-  HDRS
-    rsqrtf16.h
-  DEPENDS
-    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.FPUtil.polyeval
-    libc.src.__support.FPUtil.manipulation_functions
-    libc.src.__support.macros.optimization
-    libc.src.__support.macros.properties.types
-)
-
 add_header_library(
   asin_utils
   HDRS
@@ -775,6 +759,36 @@ add_header_library(
     libc.src.__support.common
 )
 
+add_header_library(
+  rsqrtf16
+  HDRS
+    rsqrtf16.h
+  DEPENDS
+    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.FPUtil.polyeval
+    libc.src.__support.FPUtil.manipulation_functions
+    libc.src.__support.macros.optimization
+    libc.src.__support.macros.properties.types
+)
+
+add_header_library(
+  rsqrtf
+  HDRS
+    rsqrtf.h
+  DEPENDS
+    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.FPUtil.polyeval
+    libc.src.__support.FPUtil.manipulation_functions
+    libc.src.__support.macros.optimization
+    libc.src.__support.macros.properties.types
+)
+
 add_header_library(
   sincos_eval
   HDRS
diff --git a/libc/src/math/CMakeLists.txt b/libc/src/math/CMakeLists.txt
index a6f400c873b7e..271c1c0ae1045 100644
--- a/libc/src/math/CMakeLists.txt
+++ b/libc/src/math/CMakeLists.txt
@@ -516,6 +516,7 @@ add_math_entrypoint_object(roundevenf16)
 add_math_entrypoint_object(roundevenf128)
 add_math_entrypoint_object(roundevenbf16)
 
+add_math_entrypoint_object(rsqrtf)
 add_math_entrypoint_object(rsqrtf16)
 
 add_math_entrypoint_object(scalbln)
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index ca7baeccae01a..2d92d7342ec96 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -988,6 +988,17 @@ add_entrypoint_object(
     ROUND_OPT
 )
 
+add_entrypoint_object(
+  rsqrtf
+  SRCS
+    rsqrtf.cpp
+  HDRS
+    ../rsqrtf.h
+  DEPENDS
+    libc.src.__support.math.rsqrtf
+    libc.src.errno.errno
+)
+
 add_entrypoint_object(
   rsqrtf16
   SRCS
diff --git a/libc/src/math/generic/rsqrtf.cpp b/libc/src/math/generic/rsqrtf.cpp
new file mode 100644
index 0000000000000..1c37979b35ed5
--- /dev/null
+++ b/libc/src/math/generic/rsqrtf.cpp
@@ -0,0 +1,15 @@
+//===-- Single-precision rsqrt 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/rsqrtf.h"
+#include "src/__support/math/rsqrtf.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(float, rsqrtf, (float x)) { return math::rsqrtf(x); }
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/math/rsqrtf.h b/libc/src/math/rsqrtf.h
new file mode 100644
index 0000000000000..bc559043be828
--- /dev/null
+++ b/libc/src/math/rsqrtf.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for rsqrtf ------------------------*- 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_RSQRTF_H
+#define LLVM_LIBC_SRC_MATH_RSQRTF_H
+
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+float rsqrtf(float x);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_MATH_RSQRTF_H
diff --git a/libc/test/shared/CMakeLists.txt b/libc/test/shared/CMakeLists.txt
index 495d6f0a81a4c..0fa89e3ae6b62 100644
--- a/libc/test/shared/CMakeLists.txt
+++ b/libc/test/shared/CMakeLists.txt
@@ -48,6 +48,6 @@ add_fp_unittest(
     libc.src.__support.math.ldexpf
     libc.src.__support.math.ldexpf128
     libc.src.__support.math.ldexpf16
+    libc.src.__support.math.rsqrtf
     libc.src.__support.math.rsqrtf16
-
 )
diff --git a/libc/test/shared/shared_math_test.cpp b/libc/test/shared/shared_math_test.cpp
index aa459f88c29f5..46bd112549cbd 100644
--- a/libc/test/shared/shared_math_test.cpp
+++ b/libc/test/shared/shared_math_test.cpp
@@ -67,6 +67,7 @@ TEST(LlvmLibcSharedMathTest, AllFloat) {
 
   ASSERT_FP_EQ(float(8 << 5), LIBC_NAMESPACE::shared::ldexpf(8.0f, 5));
   ASSERT_FP_EQ(float(-1 * (8 << 5)), LIBC_NAMESPACE::shared::ldexpf(-8.0f, 5));
+  EXPECT_FP_EQ(0x1p+0f, LIBC_NAMESPACE::shared::rsqrtf(1.0f));
 }
 
 TEST(LlvmLibcSharedMathTest, AllDouble) {
diff --git a/libc/test/src/math/CMakeLists.txt b/libc/test/src/math/CMakeLists.txt
index 9d644703a61ae..f728eb83ebcf4 100644
--- a/libc/test/src/math/CMakeLists.txt
+++ b/libc/test/src/math/CMakeLists.txt
@@ -1678,6 +1678,17 @@ add_fp_unittest(
     libc.src.math.sqrtl
 )
 
+add_fp_unittest(
+  rsqrtf_test
+  NEED_MPFR
+  SUITE
+    libc-math-unittests
+  SRCS
+    rsqrtf_test.cpp
+  DEPENDS
+    libc.src.math.rsqrtf
+)
+
 add_fp_unittest(
   rsqrtf16_test
   NEED_MPFR
diff --git a/libc/test/src/math/rsqrtf_test.cpp b/libc/test/src/math/rsqrtf_test.cpp
new file mode 100644
index 0000000000000..cedafb63a31de
--- /dev/null
+++ b/libc/test/src/math/rsqrtf_test.cpp
@@ -0,0 +1,41 @@
+//===-- Exhaustive test for rsqrtf ----------------------------------------===//
+//
+// 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/rsqrtf.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+#include "utils/MPFRWrapper/MPFRUtils.h"
+
+using LlvmLibcRsqrtfTest = LIBC_NAMESPACE::testing::FPTest<float>;
+
+namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
+
+// Range: [0, Inf]
+static constexpr uint32_t POS_START = 0x00000000u; 
+static constexpr uint32_t POS_STOP = 0x7F800000u;
+
+// Range: [-Inf, 0)
+// rsqrt(-0.0) is -inf, not the same for mpfr.
+static constexpr uint32_t NEG_START = 0x80000001u;
+static constexpr uint32_t NEG_STOP = 0xFF800000u;
+
+TEST_F(LlvmLibcRsqrtfTest, PositiveRange) {
+  for (uint32_t v = POS_START; v <= POS_STOP; ++v) {
+    float x = FPBits(v).get_val();
+    EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Rsqrt, x,
+                                   LIBC_NAMESPACE::rsqrtf(x), 0.5);
+  }
+}
+
+TEST_F(LlvmLibcRsqrtfTest, NegativeRange) {
+  for (uint32_t v = NEG_START; v <= NEG_STOP; ++v) {
+    float x = FPBits(v).get_val();
+    EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Rsqrt, x,
+                                   LIBC_NAMESPACE::rsqrtf(x), 0.5);
+  }
+}
diff --git a/libc/test/src/math/smoke/CMakeLists.txt b/libc/test/src/math/smoke/CMakeLists.txt
index eadd5f0970722..644fa90a412fa 100644
--- a/libc/test/src/math/smoke/CMakeLists.txt
+++ b/libc/test/src/math/smoke/CMakeLists.txt
@@ -3502,6 +3502,17 @@ add_fp_unittest(
     libc.src.math.sqrtl
 )
 
+add_fp_unittest(
+  rsqrtf_test
+  SUITE
+    libc-math-smoke-tests
+  SRCS
+    rsqrtf_test.cpp
+  DEPENDS
+    libc.src.math.rsqrtf
+    libc.hdr.errno_macros
+)
+
 add_fp_unittest(
   rsqrtf16_test
   SUITE
diff --git a/libc/test/src/math/smoke/rsqrtf_test.cpp b/libc/test/src/math/smoke/rsqrtf_test.cpp
new file mode 100644
index 0000000000000..9ffde79e5e9a7
--- /dev/null
+++ b/libc/test/src/math/smoke/rsqrtf_test.cpp
@@ -0,0 +1,42 @@
+//===-- Unittests for rsqrtf --------------------------------------------===//
+//
+// 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 "src/math/rsqrtf.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+
+using LlvmLibcRsqrtfTest = LIBC_NAMESPACE::testing::FPTest<float>;
+
+TEST_F(LlvmLibcRsqrtfTest, SpecialNumbers) {
+  EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::rsqrtf(aNaN));
+  EXPECT_MATH_ERRNO(0);
+
+  EXPECT_FP_IS_NAN_WITH_EXCEPTION(LIBC_NAMESPACE::rsqrtf(sNaN), FE_INVALID);
+  EXPECT_MATH_ERRNO(0);
+
+  EXPECT_FP_EQ(inf, LIBC_NAMESPACE::rsqrtf(zero));
+  EXPECT_MATH_ERRNO(ERANGE);
+
+  EXPECT_FP_EQ(neg_inf, LIBC_NAMESPACE::rsqrtf(neg_zero));
+  EXPECT_MATH_ERRNO(ERANGE);
+
+  EXPECT_FP_EQ(
+      1.0f,
+      LIBC_NAMESPACE::rsqrtf(1.0f));
+  EXPECT_MATH_ERRNO(0);
+
+  EXPECT_FP_EQ(zero, LIBC_NAMESPACE::rsqrtf(inf));
+  EXPECT_MATH_ERRNO(0);
+
+  EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::rsqrtf(neg_inf));
+  EXPECT_MATH_ERRNO(EDOM);
+
+  EXPECT_FP_EQ(aNaN, LIBC_NAMESPACE::rsqrtf(-2.0f));
+  EXPECT_MATH_ERRNO(EDOM);
+}
diff --git a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
index 921163a413067..87ad0926bfee6 100644
--- a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
+++ b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
@@ -2296,6 +2296,20 @@ libc_support_library(
     ],
 )
 
+libc_support_library(
+    name = "__support_math_rsqrtf",
+    hdrs = ["src/__support/math/rsqrtf.h"],
+    deps = [
+        ":__support_fputil_fenv_impl",
+        ":__support_fputil_fp_bits",
+        ":__support_fputil_manipulation_functions",
+        ":__support_fputil_multiply_add",
+        ":__support_fputil_polyeval",
+        ":__support_macros_optimization",
+        ":__support_macros_properties_types",
+    ],
+)
+
 libc_support_library(
     name = "__support_math_rsqrtf16",
     hdrs = ["src/__support/math/rsqrtf16.h"],
@@ -3259,14 +3273,6 @@ libc_math_function(
     ],
 )
 
-libc_math_function(
-    name = "rsqrtf16",
-    additional_deps = [
-        ":__support_math_rsqrtf16",
-        ":errno",
-    ],
-)
-
 libc_math_function(
     name = "acoshf16",
     additional_deps = [
@@ -4497,6 +4503,22 @@ libc_math_function(name = "roundevenf128")
 
 libc_math_function(name = "roundevenf16")
 
+libc_math_function(
+    name = "rsqrtf",
+    additional_deps = [
+        ":__support_math_rsqrtf",
+        ":errno",
+    ],
+)
+
+libc_math_function(
+    name = "rsqrtf16",
+    additional_deps = [
+        ":__support_math_rsqrtf16",
+        ":errno",
+    ],
+)
+
 libc_math_function(name = "scalbln")
 
 libc_math_function(name = "scalblnf")

>From 5b8b21a3364e121a37c7053818d574639e296d36 Mon Sep 17 00:00:00 2001
From: Anton Shepelev <shepelev777 at gmail.com>
Date: Thu, 18 Sep 2025 11:03:41 -0700
Subject: [PATCH 2/6] - clang-formatted the files - added missing header

---
 libc/src/__support/math/rsqrtf.h         | 81 ++++++++++++++++++++++++
 libc/test/src/math/rsqrtf_test.cpp       |  2 +-
 libc/test/src/math/smoke/rsqrtf_test.cpp |  4 +-
 3 files changed, 83 insertions(+), 4 deletions(-)
 create mode 100644 libc/src/__support/math/rsqrtf.h

diff --git a/libc/src/__support/math/rsqrtf.h b/libc/src/__support/math/rsqrtf.h
new file mode 100644
index 0000000000000..d31d277be68db
--- /dev/null
+++ b/libc/src/__support/math/rsqrtf.h
@@ -0,0 +1,81 @@
+//===-- Implementation header for rsqrtf ----------------------*- 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_RSQRTF_H
+#define LLVM_LIBC_SRC___SUPPORT_MATH_RSQRTF_H
+
+#include "src/__support/FPUtil/FEnvImpl.h"
+#include "src/__support/FPUtil/FPBits.h"
+#include "src/__support/FPUtil/ManipulationFunctions.h"
+#include "src/__support/FPUtil/cast.h"
+#include "src/__support/FPUtil/multiply_add.h"
+#include "src/__support/FPUtil/sqrt.h"
+#include "src/__support/macros/optimization.h"
+
+namespace LIBC_NAMESPACE_DECL {
+namespace math {
+
+LIBC_INLINE static constexpr float rsqrtf(float x) {
+  using FPBits = fputil::FPBits<float>;
+  FPBits xbits(x);
+
+  uint32_t x_u = xbits.uintval();
+  uint32_t x_abs = x_u & 0x7fff'ffffU;
+
+  constexpr uint32_t INF_BIT = FPBits::inf().uintval();
+
+  // x is 0, inf/nan, or negative.
+  if (LIBC_UNLIKELY(x_u == 0 || x_u >= INF_BIT)) {
+    // x is NaN
+    if (x_abs > INF_BIT) {
+      if (xbits.is_signaling_nan()) {
+        fputil::raise_except_if_required(FE_INVALID);
+        return FPBits::quiet_nan().get_val();
+      }
+      return x;
+    }
+
+    // |x| = 0
+    if (x_abs == 0) {
+      fputil::raise_except_if_required(FE_DIVBYZERO);
+      fputil::set_errno_if_required(ERANGE);
+      return FPBits::inf(xbits.sign()).get_val();
+    }
+
+    // -inf <= x < 0
+    if (x_u > 0x7fff'ffffU) {
+      fputil::raise_except_if_required(FE_INVALID);
+      fputil::set_errno_if_required(EDOM);
+      return FPBits::quiet_nan().get_val();
+    }
+
+    // x = +inf => rsqrt(x) = 0
+    return FPBits::zero().get_val();
+  }
+
+  // TODO: add integer based implementation when LIBC_TARGET_CPU_HAS_FPU_FLOAT
+  // is not defined
+  double result = 1.0f / fputil::sqrt<double>(fputil::cast<double>(x));
+
+  // Targeted post-corrections to ensure correct rounding in half for specific
+  // mantissa patterns
+  /*
+  const uint32_t half_mantissa = x_abs & 0x3ff;
+  if (LIBC_UNLIKELY(half_mantissa == 0x011F)) {
+    result = fputil::multiply_add(result, 0x1.0p-21f, result);
+  } else if (LIBC_UNLIKELY(half_mantissa == 0x0313)) {
+    result = fputil::multiply_add(result, -0x1.0p-21f, result);
+  }*/
+
+  return fputil::cast<float>(result);
+}
+
+} // namespace math
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_MATH_RSQRTF_H
diff --git a/libc/test/src/math/rsqrtf_test.cpp b/libc/test/src/math/rsqrtf_test.cpp
index cedafb63a31de..3287dc8b5d0d5 100644
--- a/libc/test/src/math/rsqrtf_test.cpp
+++ b/libc/test/src/math/rsqrtf_test.cpp
@@ -16,7 +16,7 @@ using LlvmLibcRsqrtfTest = LIBC_NAMESPACE::testing::FPTest<float>;
 namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
 
 // Range: [0, Inf]
-static constexpr uint32_t POS_START = 0x00000000u; 
+static constexpr uint32_t POS_START = 0x00000000u;
 static constexpr uint32_t POS_STOP = 0x7F800000u;
 
 // Range: [-Inf, 0)
diff --git a/libc/test/src/math/smoke/rsqrtf_test.cpp b/libc/test/src/math/smoke/rsqrtf_test.cpp
index 9ffde79e5e9a7..02f67c4378197 100644
--- a/libc/test/src/math/smoke/rsqrtf_test.cpp
+++ b/libc/test/src/math/smoke/rsqrtf_test.cpp
@@ -26,9 +26,7 @@ TEST_F(LlvmLibcRsqrtfTest, SpecialNumbers) {
   EXPECT_FP_EQ(neg_inf, LIBC_NAMESPACE::rsqrtf(neg_zero));
   EXPECT_MATH_ERRNO(ERANGE);
 
-  EXPECT_FP_EQ(
-      1.0f,
-      LIBC_NAMESPACE::rsqrtf(1.0f));
+  EXPECT_FP_EQ(1.0f, LIBC_NAMESPACE::rsqrtf(1.0f));
   EXPECT_MATH_ERRNO(0);
 
   EXPECT_FP_EQ(zero, LIBC_NAMESPACE::rsqrtf(inf));

>From 26674a6a2d7b4980795ba9837ce80c3596de89bc Mon Sep 17 00:00:00 2001
From: Anton Shepelev <shepelev777 at gmail.com>
Date: Fri, 19 Sep 2025 11:22:58 -0700
Subject: [PATCH 3/6] - Created exhaustive test for rsqrt in
 libc/test/src/math/exhaustive/ - Created unit test template for rsqrt
 functions that can be called in the future by other precision functions -
 Changed range of values for unit-test to match the
 libc/test/src/math/SqrtTest.h - Changed the comments in rsqrtf.h, removed
 unnecessary code in the comments

---
 libc/src/__support/math/rsqrtf.h              | 14 +---
 libc/test/src/math/RsqrtTest.h                | 74 +++++++++++++++++++
 libc/test/src/math/exhaustive/CMakeLists.txt  | 16 ++++
 libc/test/src/math/exhaustive/rsqrtf_test.cpp | 27 +++++++
 libc/test/src/math/rsqrtf_test.cpp            | 37 +---------
 5 files changed, 123 insertions(+), 45 deletions(-)
 create mode 100644 libc/test/src/math/RsqrtTest.h
 create mode 100644 libc/test/src/math/exhaustive/rsqrtf_test.cpp

diff --git a/libc/src/__support/math/rsqrtf.h b/libc/src/__support/math/rsqrtf.h
index d31d277be68db..ae3cf26317dc0 100644
--- a/libc/src/__support/math/rsqrtf.h
+++ b/libc/src/__support/math/rsqrtf.h
@@ -58,20 +58,10 @@ LIBC_INLINE static constexpr float rsqrtf(float x) {
     return FPBits::zero().get_val();
   }
 
-  // TODO: add integer based implementation when LIBC_TARGET_CPU_HAS_FPU_FLOAT
-  // is not defined
+  // TODO: add float based approximation when
+  // LIBC_TARGET_CPU_HAS_FPU_DOUBLE is not defined
   double result = 1.0f / fputil::sqrt<double>(fputil::cast<double>(x));
 
-  // Targeted post-corrections to ensure correct rounding in half for specific
-  // mantissa patterns
-  /*
-  const uint32_t half_mantissa = x_abs & 0x3ff;
-  if (LIBC_UNLIKELY(half_mantissa == 0x011F)) {
-    result = fputil::multiply_add(result, 0x1.0p-21f, result);
-  } else if (LIBC_UNLIKELY(half_mantissa == 0x0313)) {
-    result = fputil::multiply_add(result, -0x1.0p-21f, result);
-  }*/
-
   return fputil::cast<float>(result);
 }
 
diff --git a/libc/test/src/math/RsqrtTest.h b/libc/test/src/math/RsqrtTest.h
new file mode 100644
index 0000000000000..8cabc14fd2d28
--- /dev/null
+++ b/libc/test/src/math/RsqrtTest.h
@@ -0,0 +1,74 @@
+//===-- Utility class to test rsqrt -----------------------------*- 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_TEST_SRC_MATH_RSQRTTEST_H
+#define LLVM_LIBC_TEST_SRC_MATH_RSQRTTEST_H
+
+#include "test/UnitTest/FEnvSafeTest.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+#include "utils/MPFRWrapper/MPFRUtils.h"
+
+namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
+
+template <typename OutType, typename InType = OutType>
+class RsqrtTest : public LIBC_NAMESPACE::testing::FEnvSafeTest {
+
+  DECLARE_SPECIAL_CONSTANTS(InType)
+
+  static constexpr StorageType HIDDEN_BIT =
+      StorageType(1) << LIBC_NAMESPACE::fputil::FPBits<InType>::FRACTION_LEN;
+
+public:
+  using RsqrtFunc = OutType (*)(InType);
+
+  // Subnormal inputs: probe both power-of-two mantissas and an even sampling
+  // across the subnormal range.
+  void test_denormal_values(RsqrtFunc func) {
+    // Powers of two in the subnormal mantissa space.
+    for (StorageType mant = 1; mant < HIDDEN_BIT; mant <<= 1) {
+      FPBits denormal(zero);
+      denormal.set_mantissa(mant);
+      InType x = denormal.get_val();
+      ASSERT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Rsqrt, x, func(x), 0.5);
+    }
+
+    // Even sampling across all subnormals.
+    constexpr StorageType COUNT = 200'001;
+    constexpr StorageType STEP = HIDDEN_BIT / COUNT;
+    for (StorageType i = 0, v = 0; i <= COUNT; ++i, v += STEP) {
+      InType x = FPBits(i).get_val();
+      ASSERT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Rsqrt, x, func(x), 0.5);
+    }
+  }
+
+  // Positive normal range sampling: skip NaNs and negative values.
+  void test_normal_range(RsqrtFunc func) {
+    constexpr StorageType COUNT = 200'001;
+    constexpr StorageType STEP = STORAGE_MAX / COUNT;
+    for (StorageType i = 0, v = 0; i <= COUNT; ++i, v += STEP) {
+      FPBits x_bits(v);
+      InType x = x_bits.get_val();
+      if (x_bits.is_nan() || (x < static_cast<InType>(0)))
+        continue;
+      ASSERT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Rsqrt, x, func(x), 0.5);
+    }
+  }
+};
+
+#define LIST_RSQRT_TESTS(T, func)                                              \
+  using LlvmLibcRsqrtTest = RsqrtTest<T, T>;                                   \
+  TEST_F(LlvmLibcRsqrtTest, DenormalValues) { test_denormal_values(&func); }   \
+  TEST_F(LlvmLibcRsqrtTest, NormalRange) { test_normal_range(&func); }
+
+#define LIST_NARROWING_RSQRT_TESTS(OutType, InType, func)                      \
+  using LlvmLibcRsqrtTest = RsqrtTest<OutType, InType>;                        \
+  TEST_F(LlvmLibcRsqrtTest, DenormalValues) { test_denormal_values(&func); }   \
+  TEST_F(LlvmLibcRsqrtTest, NormalRange) { test_normal_range(&func); }
+
+#endif // LLVM_LIBC_TEST_SRC_MATH_RSQRTTEST_H
diff --git a/libc/test/src/math/exhaustive/CMakeLists.txt b/libc/test/src/math/exhaustive/CMakeLists.txt
index 07c36f424a0c3..c73a870fc0c09 100644
--- a/libc/test/src/math/exhaustive/CMakeLists.txt
+++ b/libc/test/src/math/exhaustive/CMakeLists.txt
@@ -26,6 +26,22 @@ add_fp_unittest(
     -lpthread
 )
 
+add_fp_unittest(
+  rsqrtf_test
+  NO_RUN_POSTBUILD
+  NEED_MPFR
+  SUITE
+    libc_math_exhaustive_tests
+  SRCS
+    rsqrtf_test.cpp
+  DEPENDS
+    .exhaustive_test
+    libc.src.math.rsqrtf
+    libc.src.__support.FPUtil.fp_bits
+  LINK_LIBRARIES
+    -lpthread
+)
+
 add_fp_unittest(
   sinf_test
   NO_RUN_POSTBUILD
diff --git a/libc/test/src/math/exhaustive/rsqrtf_test.cpp b/libc/test/src/math/exhaustive/rsqrtf_test.cpp
new file mode 100644
index 0000000000000..803c9b4820fc2
--- /dev/null
+++ b/libc/test/src/math/exhaustive/rsqrtf_test.cpp
@@ -0,0 +1,27 @@
+//===-- Exhaustive test for rsqrtf ----------------------------------------===//
+//
+// 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 "exhaustive_test.h"
+#include "src/math/rsqrtf.h"
+#include "utils/MPFRWrapper/MPFRUtils.h"
+
+using LlvmLibcRsqrtfTest = LIBC_NAMESPACE::testing::FPTest<float>;
+
+using LlvmLibcRsqrtfExhaustiveTest =
+    LlvmLibcUnaryOpExhaustiveMathTest<float, mpfr::Operation::Rsqrt,
+                                      LIBC_NAMESPACE::rsqrtf>;
+
+namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
+
+// Range: [0, Inf]
+static constexpr uint32_t POS_START = 0x0000'0000U;
+static constexpr uint32_t POS_STOP = 0x7f80'0000U;
+
+TEST_F(LlvmLibcRsqrtfExhaustiveTest, PositiveRange) {
+  test_full_range_all_roundings(POS_START, POS_STOP);
+}
diff --git a/libc/test/src/math/rsqrtf_test.cpp b/libc/test/src/math/rsqrtf_test.cpp
index 3287dc8b5d0d5..4e476c0be8d41 100644
--- a/libc/test/src/math/rsqrtf_test.cpp
+++ b/libc/test/src/math/rsqrtf_test.cpp
@@ -1,41 +1,12 @@
-//===-- Exhaustive test for rsqrtf ----------------------------------------===//
-//
+//===-- Unittests for rsqrtf ----------------------------------------------===//
 // 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/rsqrtf.h"
-#include "test/UnitTest/FPMatcher.h"
-#include "test/UnitTest/Test.h"
-#include "utils/MPFRWrapper/MPFRUtils.h"
-
-using LlvmLibcRsqrtfTest = LIBC_NAMESPACE::testing::FPTest<float>;
-
-namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
+#include "RsqrtTest.h"
 
-// Range: [0, Inf]
-static constexpr uint32_t POS_START = 0x00000000u;
-static constexpr uint32_t POS_STOP = 0x7F800000u;
-
-// Range: [-Inf, 0)
-// rsqrt(-0.0) is -inf, not the same for mpfr.
-static constexpr uint32_t NEG_START = 0x80000001u;
-static constexpr uint32_t NEG_STOP = 0xFF800000u;
-
-TEST_F(LlvmLibcRsqrtfTest, PositiveRange) {
-  for (uint32_t v = POS_START; v <= POS_STOP; ++v) {
-    float x = FPBits(v).get_val();
-    EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Rsqrt, x,
-                                   LIBC_NAMESPACE::rsqrtf(x), 0.5);
-  }
-}
+#include "src/math/rsqrtf.h"
 
-TEST_F(LlvmLibcRsqrtfTest, NegativeRange) {
-  for (uint32_t v = NEG_START; v <= NEG_STOP; ++v) {
-    float x = FPBits(v).get_val();
-    EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Rsqrt, x,
-                                   LIBC_NAMESPACE::rsqrtf(x), 0.5);
-  }
-}
+LIST_RSQRT_TESTS(float, LIBC_NAMESPACE::rsqrtf)

>From 0d8e57a9cdc07a920e65a78e69e0211e3e9d85f1 Mon Sep 17 00:00:00 2001
From: Anton Shepelev <shepelev777 at gmail.com>
Date: Fri, 19 Sep 2025 12:22:09 -0700
Subject: [PATCH 4/6] - Added comments to RsqrtTest.h template, to clarify use
 case

---
 libc/test/src/math/RsqrtTest.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libc/test/src/math/RsqrtTest.h b/libc/test/src/math/RsqrtTest.h
index 8cabc14fd2d28..14cb708176237 100644
--- a/libc/test/src/math/RsqrtTest.h
+++ b/libc/test/src/math/RsqrtTest.h
@@ -1,4 +1,4 @@
-//===-- Utility class to test rsqrt -----------------------------*- C++ -*-===//
+//===-- Utility class to test rsqrt[f|l] ------------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.

>From 1cc47f3078dc9270f40d75fac44ec423b4a32a5c Mon Sep 17 00:00:00 2001
From: Anton Shepelev <shepelev777 at gmail.com>
Date: Wed, 24 Sep 2025 13:44:51 -0700
Subject: [PATCH 5/6] Addressed the comments, fixed include in
 rsqrtf16_test.cpp and cmake to match rsqrtf_test.cpp

---
 libc/src/__support/math/CMakeLists.txt        | 20 +++++++++----------
 libc/src/__support/math/rsqrtf.h              | 20 +++++++++----------
 libc/src/math/generic/CMakeLists.txt          |  1 -
 libc/src/math/generic/rsqrtf.cpp              |  1 +
 libc/test/src/math/RsqrtTest.h                |  2 +-
 libc/test/src/math/exhaustive/CMakeLists.txt  |  1 -
 libc/test/src/math/smoke/CMakeLists.txt       |  8 +++++---
 libc/test/src/math/smoke/rsqrtf16_test.cpp    |  3 ++-
 libc/test/src/math/smoke/rsqrtf_test.cpp      |  3 ++-
 .../llvm-project-overlay/libc/BUILD.bazel     | 14 ++++++-------
 10 files changed, 36 insertions(+), 37 deletions(-)

diff --git a/libc/src/__support/math/CMakeLists.txt b/libc/src/__support/math/CMakeLists.txt
index 26ad5a1d8901a..7fd91e116ff0c 100644
--- a/libc/src/__support/math/CMakeLists.txt
+++ b/libc/src/__support/math/CMakeLists.txt
@@ -760,24 +760,22 @@ add_header_library(
 )
 
 add_header_library(
-  rsqrtf16
+  rsqrtf
   HDRS
-    rsqrtf16.h
+    rsqrtf.h
   DEPENDS
-    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.FPUtil.polyeval
-    libc.src.__support.FPUtil.manipulation_functions
+    libc.hdr.errno_macros  
+    libc.hdr.fenv_macros  
+    libc.src.__support.FPUtil.cast  
+    libc.src.__support.FPUtil.fenv_impl  
+    libc.src.__support.FPUtil.fp_bits  
     libc.src.__support.macros.optimization
-    libc.src.__support.macros.properties.types
 )
 
 add_header_library(
-  rsqrtf
+  rsqrtf16
   HDRS
-    rsqrtf.h
+    rsqrtf16.h
   DEPENDS
     libc.src.__support.FPUtil.cast
     libc.src.__support.FPUtil.fenv_impl
diff --git a/libc/src/__support/math/rsqrtf.h b/libc/src/__support/math/rsqrtf.h
index ae3cf26317dc0..2b2531f9fbc0f 100644
--- a/libc/src/__support/math/rsqrtf.h
+++ b/libc/src/__support/math/rsqrtf.h
@@ -1,4 +1,4 @@
-//===-- Implementation header for rsqrtf ----------------------*- C++ -*-===//
+//===-- Implementation header for rsqrtf ------------------------*- C++ -*-===//  
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
@@ -9,11 +9,11 @@
 #ifndef LLVM_LIBC_SRC___SUPPORT_MATH_RSQRTF_H
 #define LLVM_LIBC_SRC___SUPPORT_MATH_RSQRTF_H
 
-#include "src/__support/FPUtil/FEnvImpl.h"
-#include "src/__support/FPUtil/FPBits.h"
-#include "src/__support/FPUtil/ManipulationFunctions.h"
-#include "src/__support/FPUtil/cast.h"
-#include "src/__support/FPUtil/multiply_add.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/cast.h"  
 #include "src/__support/FPUtil/sqrt.h"
 #include "src/__support/macros/optimization.h"
 
@@ -27,12 +27,12 @@ LIBC_INLINE static constexpr float rsqrtf(float x) {
   uint32_t x_u = xbits.uintval();
   uint32_t x_abs = x_u & 0x7fff'ffffU;
 
-  constexpr uint32_t INF_BIT = FPBits::inf().uintval();
+  constexpr uint32_t INF_BITS = FPBits::inf().uintval();
 
   // x is 0, inf/nan, or negative.
-  if (LIBC_UNLIKELY(x_u == 0 || x_u >= INF_BIT)) {
+  if (LIBC_UNLIKELY(x_u == 0 || x_u >= INF_BITS)) {
     // x is NaN
-    if (x_abs > INF_BIT) {
+    if (x_abs > INF_BITS) {
       if (xbits.is_signaling_nan()) {
         fputil::raise_except_if_required(FE_INVALID);
         return FPBits::quiet_nan().get_val();
@@ -55,7 +55,7 @@ LIBC_INLINE static constexpr float rsqrtf(float x) {
     }
 
     // x = +inf => rsqrt(x) = 0
-    return FPBits::zero().get_val();
+    return FPBits::zero(xbits.sign()).get_val();
   }
 
   // TODO: add float based approximation when
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index 2d92d7342ec96..54dc16d57baf5 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -996,7 +996,6 @@ add_entrypoint_object(
     ../rsqrtf.h
   DEPENDS
     libc.src.__support.math.rsqrtf
-    libc.src.errno.errno
 )
 
 add_entrypoint_object(
diff --git a/libc/src/math/generic/rsqrtf.cpp b/libc/src/math/generic/rsqrtf.cpp
index 1c37979b35ed5..6a38fa7d43d2e 100644
--- a/libc/src/math/generic/rsqrtf.cpp
+++ b/libc/src/math/generic/rsqrtf.cpp
@@ -12,4 +12,5 @@
 namespace LIBC_NAMESPACE_DECL {
 
 LLVM_LIBC_FUNCTION(float, rsqrtf, (float x)) { return math::rsqrtf(x); }
+
 } // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/test/src/math/RsqrtTest.h b/libc/test/src/math/RsqrtTest.h
index 14cb708176237..d11d708f644d9 100644
--- a/libc/test/src/math/RsqrtTest.h
+++ b/libc/test/src/math/RsqrtTest.h
@@ -54,7 +54,7 @@ class RsqrtTest : public LIBC_NAMESPACE::testing::FEnvSafeTest {
     for (StorageType i = 0, v = 0; i <= COUNT; ++i, v += STEP) {
       FPBits x_bits(v);
       InType x = x_bits.get_val();
-      if (x_bits.is_nan() || (x < static_cast<InType>(0)))
+      if (x_bits.is_nan() || x_bits.is_neg())
         continue;
       ASSERT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Rsqrt, x, func(x), 0.5);
     }
diff --git a/libc/test/src/math/exhaustive/CMakeLists.txt b/libc/test/src/math/exhaustive/CMakeLists.txt
index c73a870fc0c09..1583ab6f74680 100644
--- a/libc/test/src/math/exhaustive/CMakeLists.txt
+++ b/libc/test/src/math/exhaustive/CMakeLists.txt
@@ -37,7 +37,6 @@ add_fp_unittest(
   DEPENDS
     .exhaustive_test
     libc.src.math.rsqrtf
-    libc.src.__support.FPUtil.fp_bits
   LINK_LIBRARIES
     -lpthread
 )
diff --git a/libc/test/src/math/smoke/CMakeLists.txt b/libc/test/src/math/smoke/CMakeLists.txt
index 644fa90a412fa..28f20f7956551 100644
--- a/libc/test/src/math/smoke/CMakeLists.txt
+++ b/libc/test/src/math/smoke/CMakeLists.txt
@@ -3509,8 +3509,9 @@ add_fp_unittest(
   SRCS
     rsqrtf_test.cpp
   DEPENDS
-    libc.src.math.rsqrtf
-    libc.hdr.errno_macros
+    libc.hdr.errno_macros  
+    libc.hdr.fenv_macros  
+    libc.src.math.rsqrtf 
 )
 
 add_fp_unittest(
@@ -3520,8 +3521,9 @@ add_fp_unittest(
   SRCS
     rsqrtf16_test.cpp
   DEPENDS
+    libc.hdr.errno_macros  
+    libc.hdr.fenv_macros 
     libc.src.math.rsqrtf16
-    libc.hdr.errno_macros
 )
 
 add_fp_unittest(
diff --git a/libc/test/src/math/smoke/rsqrtf16_test.cpp b/libc/test/src/math/smoke/rsqrtf16_test.cpp
index 5eb3e2fd6692c..c24972d7ba29d 100644
--- a/libc/test/src/math/smoke/rsqrtf16_test.cpp
+++ b/libc/test/src/math/smoke/rsqrtf16_test.cpp
@@ -6,7 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "hdr/errno_macros.h"
+#include "hdr/fenv_macros.h"  
+#include "hdr/errno_macros.h" 
 #include "src/__support/FPUtil/cast.h"
 #include "src/math/rsqrtf16.h"
 #include "test/UnitTest/FPMatcher.h"
diff --git a/libc/test/src/math/smoke/rsqrtf_test.cpp b/libc/test/src/math/smoke/rsqrtf_test.cpp
index 02f67c4378197..0644c07d042a6 100644
--- a/libc/test/src/math/smoke/rsqrtf_test.cpp
+++ b/libc/test/src/math/smoke/rsqrtf_test.cpp
@@ -6,7 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "hdr/errno_macros.h"
+#include "hdr/fenv_macros.h"  
+#include "hdr/errno_macros.h" 
 #include "src/math/rsqrtf.h"
 #include "test/UnitTest/FPMatcher.h"
 #include "test/UnitTest/Test.h"
diff --git a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
index 87ad0926bfee6..1466545d50d3e 100644
--- a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
+++ b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
@@ -2300,13 +2300,12 @@ libc_support_library(
     name = "__support_math_rsqrtf",
     hdrs = ["src/__support/math/rsqrtf.h"],
     deps = [
-        ":__support_fputil_fenv_impl",
-        ":__support_fputil_fp_bits",
-        ":__support_fputil_manipulation_functions",
-        ":__support_fputil_multiply_add",
-        ":__support_fputil_polyeval",
-        ":__support_macros_optimization",
-        ":__support_macros_properties_types",
+        ":hdr_errno_macros",  
+        ":hdr_fenv_macros",  
+        ":__support_fputil_cast",  
+        ":__support_fputil_fenv_impl",  
+        ":__support_fputil_fp_bits",  
+        ":__support_macros_optimization",  
     ],
 )
 
@@ -4507,7 +4506,6 @@ libc_math_function(
     name = "rsqrtf",
     additional_deps = [
         ":__support_math_rsqrtf",
-        ":errno",
     ],
 )
 

>From 0faacb661a3828aa8e64901e6c88b51d36c6eb57 Mon Sep 17 00:00:00 2001
From: Anton Shepelev <shepelev777 at gmail.com>
Date: Wed, 24 Sep 2025 13:57:45 -0700
Subject: [PATCH 6/6] Clang-formatted the files in question, ran Buildifier on
 .bazel

---
 libc/src/__support/math/rsqrtf.h                  | 12 ++++++------
 libc/test/src/math/smoke/rsqrtf16_test.cpp        |  4 ++--
 libc/test/src/math/smoke/rsqrtf_test.cpp          |  4 ++--
 utils/bazel/llvm-project-overlay/libc/BUILD.bazel | 12 ++++++------
 4 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/libc/src/__support/math/rsqrtf.h b/libc/src/__support/math/rsqrtf.h
index 2b2531f9fbc0f..cbdf2663f08c9 100644
--- a/libc/src/__support/math/rsqrtf.h
+++ b/libc/src/__support/math/rsqrtf.h
@@ -1,4 +1,4 @@
-//===-- Implementation header for rsqrtf ------------------------*- C++ -*-===//  
+//===-- Implementation header for rsqrtf ------------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
@@ -9,11 +9,11 @@
 #ifndef LLVM_LIBC_SRC___SUPPORT_MATH_RSQRTF_H
 #define LLVM_LIBC_SRC___SUPPORT_MATH_RSQRTF_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/cast.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/cast.h"
 #include "src/__support/FPUtil/sqrt.h"
 #include "src/__support/macros/optimization.h"
 
diff --git a/libc/test/src/math/smoke/rsqrtf16_test.cpp b/libc/test/src/math/smoke/rsqrtf16_test.cpp
index c24972d7ba29d..24e8be400a366 100644
--- a/libc/test/src/math/smoke/rsqrtf16_test.cpp
+++ b/libc/test/src/math/smoke/rsqrtf16_test.cpp
@@ -6,8 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "hdr/fenv_macros.h"  
-#include "hdr/errno_macros.h" 
+#include "hdr/errno_macros.h"
+#include "hdr/fenv_macros.h"
 #include "src/__support/FPUtil/cast.h"
 #include "src/math/rsqrtf16.h"
 #include "test/UnitTest/FPMatcher.h"
diff --git a/libc/test/src/math/smoke/rsqrtf_test.cpp b/libc/test/src/math/smoke/rsqrtf_test.cpp
index 0644c07d042a6..d71b82c1e5be1 100644
--- a/libc/test/src/math/smoke/rsqrtf_test.cpp
+++ b/libc/test/src/math/smoke/rsqrtf_test.cpp
@@ -6,8 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "hdr/fenv_macros.h"  
-#include "hdr/errno_macros.h" 
+#include "hdr/errno_macros.h"
+#include "hdr/fenv_macros.h"
 #include "src/math/rsqrtf.h"
 #include "test/UnitTest/FPMatcher.h"
 #include "test/UnitTest/Test.h"
diff --git a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
index 1466545d50d3e..a275bcbbd3e58 100644
--- a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
+++ b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
@@ -2300,12 +2300,12 @@ libc_support_library(
     name = "__support_math_rsqrtf",
     hdrs = ["src/__support/math/rsqrtf.h"],
     deps = [
-        ":hdr_errno_macros",  
-        ":hdr_fenv_macros",  
-        ":__support_fputil_cast",  
-        ":__support_fputil_fenv_impl",  
-        ":__support_fputil_fp_bits",  
-        ":__support_macros_optimization",  
+        ":__support_fputil_cast",
+        ":__support_fputil_fenv_impl",
+        ":__support_fputil_fp_bits",
+        ":__support_macros_optimization",
+        ":hdr_errno_macros",
+        ":hdr_fenv_macros",
     ],
 )
 



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