[libc][math][c23] Add rsqrtf() function #159615
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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
amemov
requested review from
rupprecht,
keith and
aaronmondal
as code owners
llvmbot
added
backend:RISC-V
libc
bazel
|
@llvm/pr-subscribers-backend-risc-v @llvm/pr-subscribers-libc Author: Anton Shepelev (amemov) ChangesAddresses #159614 Changes:
Some small unrelated style changes to this PR (that I missed in my rsqrtf16 PR):
Full diff: https://github.com/llvm/llvm-project/pull/159615.diff 20 Files Affected:
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")
|
|
✅ With the latest revision this PR passed the C/C++ code formatter. |
- added missing header
|
@lntue I implemented the |
- 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
|
@amemov FYI, you need to write "Fixes #(issue number)" or "Closes #(issue number)" (or a few variations of these) instead of "Addresses #(issue number)" for GitHub to automatically close the issue once the PR is merged. |
overmighty
requested changes
Sep 24, 2025
overmighty
requested changes
Oct 4, 2025
overmighty
reviewed
Oct 4, 2025
| deps = [ | ||
| ":__support_fputil_cast", | ||
| ":__support_fputil_fenv_impl", | ||
| ":__support_fputil_fp_bits", |
There was a problem hiding this comment.
Suggested change
| ":__support_fputil_fp_bits", | |
| ":__support_fputil_fp_bits", | |
| ":__support_fputil_sqrt", |
There was a problem hiding this comment.
Why did you remove cast? If I understand correctly, here in the bazel it should add the same dependencies as CMake in libc/src/__support/math , which are:
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.FPUtil.sqrt
libc.src.__support.macros.optimization
overmighty
reviewed
Oct 4, 2025
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Closes #159614
Changes:
Some small unrelated style changes to this PR (that I missed in my rsqrtf16 PR):