[libc-commits] [libc] [libc][stdfix] Add sqrt for fixed point types. (PR #83042)
via libc-commits
libc-commits at lists.llvm.org
Mon Feb 26 11:28:31 PST 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-libc
Author: None (lntue)
<details>
<summary>Changes</summary>
---
Patch is 25.53 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/83042.diff
23 Files Affected:
- (modified) libc/config/linux/x86_64/entrypoints.txt (+6)
- (modified) libc/docs/math/stdfix.rst (+1-1)
- (modified) libc/spec/stdc_ext.td (+8)
- (modified) libc/src/__support/fixed_point/CMakeLists.txt (+13)
- (added) libc/src/__support/fixed_point/sqrt.h (+139)
- (modified) libc/src/stdfix/CMakeLists.txt (+15)
- (added) libc/src/stdfix/sqrtuhk.cpp (+19)
- (added) libc/src/stdfix/sqrtuhk.h (+20)
- (added) libc/src/stdfix/sqrtuhr.cpp (+19)
- (added) libc/src/stdfix/sqrtuhr.h (+20)
- (added) libc/src/stdfix/sqrtuk.cpp (+19)
- (added) libc/src/stdfix/sqrtuk.h (+20)
- (added) libc/src/stdfix/sqrtulr.cpp (+19)
- (added) libc/src/stdfix/sqrtulr.h (+20)
- (added) libc/src/stdfix/sqrtur.cpp (+19)
- (added) libc/src/stdfix/sqrtur.h (+20)
- (modified) libc/test/src/stdfix/CMakeLists.txt (+22)
- (added) libc/test/src/stdfix/SqrtTest.h (+66)
- (added) libc/test/src/stdfix/sqrtuhk_test.cpp (+13)
- (added) libc/test/src/stdfix/sqrtuhr_test.cpp (+13)
- (added) libc/test/src/stdfix/sqrtuk_test.cpp (+13)
- (added) libc/test/src/stdfix/sqrtulr_test.cpp (+13)
- (added) libc/test/src/stdfix/sqrtur_test.cpp (+13)
``````````diff
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index f2a224d45bbae7..cd44b5c52b58cd 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -473,6 +473,12 @@ if(LIBC_COMPILER_HAS_FIXED_POINT)
libc.src.stdfix.roundur
libc.src.stdfix.roundulk
libc.src.stdfix.roundulr
+ libc.src.stdfix.sqrtuhk
+ libc.src.stdfix.sqrtuhr
+ libc.src.stdfix.sqrtuk
+ libc.src.stdfix.sqrtur
+ # libc.src.stdfix.sqrtulk
+ libc.src.stdfix.sqrtulr
)
endif()
diff --git a/libc/docs/math/stdfix.rst b/libc/docs/math/stdfix.rst
index 080066e53bd2f1..79f499e61f121c 100644
--- a/libc/docs/math/stdfix.rst
+++ b/libc/docs/math/stdfix.rst
@@ -78,7 +78,7 @@ Fixed-point Arithmetics
+---------------+----------------+-------------+---------------+------------+----------------+-------------+----------------+-------------+---------------+------------+----------------+-------------+
| round | |check| | |check| | |check| | |check| | |check| | |check| | |check| | |check| | |check| | |check| | |check| | |check| |
+---------------+----------------+-------------+---------------+------------+----------------+-------------+----------------+-------------+---------------+------------+----------------+-------------+
-| sqrt | | | | | | | | | | | | |
+| sqrt | |check| | | |check| | | |check| | | |check| | | |check| | | | |
+---------------+----------------+-------------+---------------+------------+----------------+-------------+----------------+-------------+---------------+------------+----------------+-------------+
================== =========
diff --git a/libc/spec/stdc_ext.td b/libc/spec/stdc_ext.td
index 6620142146c471..be1e6d4ba2fcdc 100644
--- a/libc/spec/stdc_ext.td
+++ b/libc/spec/stdc_ext.td
@@ -47,6 +47,14 @@ def StdcExt : StandardSpec<"stdc_ext"> {
GuardedFunctionSpec<"rounduhk", RetValSpec<UnsignedShortAccumType>, [ArgSpec<UnsignedShortAccumType>, ArgSpec<IntType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
GuardedFunctionSpec<"rounduk", RetValSpec<UnsignedAccumType>, [ArgSpec<UnsignedAccumType>, ArgSpec<IntType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
GuardedFunctionSpec<"roundulk", RetValSpec<UnsignedLongAccumType>, [ArgSpec<UnsignedLongAccumType>, ArgSpec<IntType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
+
+ GuardedFunctionSpec<"sqrtuhr", RetValSpec<UnsignedShortFractType>, [ArgSpec<UnsignedShortFractType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
+ GuardedFunctionSpec<"sqrtur", RetValSpec<UnsignedFractType>, [ArgSpec<UnsignedFractType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
+ GuardedFunctionSpec<"sqrtulr", RetValSpec<UnsignedLongFractType>, [ArgSpec<UnsignedLongFractType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
+
+ GuardedFunctionSpec<"sqrtuhk", RetValSpec<UnsignedShortAccumType>, [ArgSpec<UnsignedShortAccumType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
+ GuardedFunctionSpec<"sqrtuk", RetValSpec<UnsignedAccumType>, [ArgSpec<UnsignedAccumType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
+ GuardedFunctionSpec<"sqrtulk", RetValSpec<UnsignedLongAccumType>, [ArgSpec<UnsignedLongAccumType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
]
>;
diff --git a/libc/src/__support/fixed_point/CMakeLists.txt b/libc/src/__support/fixed_point/CMakeLists.txt
index 64f9dacc7ba5f0..0ed118f2408849 100644
--- a/libc/src/__support/fixed_point/CMakeLists.txt
+++ b/libc/src/__support/fixed_point/CMakeLists.txt
@@ -21,3 +21,16 @@ add_header_library(
libc.src.__support.CPP.bit
libc.src.__support.math_extras
)
+
+add_header_library(
+ sqrt
+ HDRS
+ sqrt.h
+ DEPENDS
+ .fx_rep
+ libc.include.llvm-libc-macros.stdfix_macros
+ libc.src.__support.macros.attributes
+ libc.src.__support.macros.optimization
+ libc.src.__support.CPP.bit
+ libc.src.__support.CPP.type_traits
+)
diff --git a/libc/src/__support/fixed_point/sqrt.h b/libc/src/__support/fixed_point/sqrt.h
new file mode 100644
index 00000000000000..dcf2c715497130
--- /dev/null
+++ b/libc/src/__support/fixed_point/sqrt.h
@@ -0,0 +1,139 @@
+//===-- Calculate square root of fixed point numbers. -----*- 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_FIXEDPOINT_SQRT_H
+#define LLVM_LIBC_SRC___SUPPORT_FIXEDPOINT_SQRT_H
+
+#include "include/llvm-libc-macros/stdfix-macros.h"
+#include "src/__support/CPP/bit.h"
+#include "src/__support/CPP/type_traits.h"
+#include "src/__support/macros/attributes.h" // LIBC_INLINE
+#include "src/__support/macros/optimization.h" // LIBC_UNLIKELY
+
+#include "fx_rep.h"
+
+#ifdef LIBC_COMPILER_HAS_FIXED_POINT
+
+namespace LIBC_NAMESPACE::fixed_point {
+
+namespace internal {
+
+template <typename T> struct SqrtConfig;
+
+template <> struct SqrtConfig<unsigned short fract> {
+ using Type = unsigned short fract;
+ static constexpr int EXTRA_STEPS = 0;
+};
+
+template <> struct SqrtConfig<unsigned fract> {
+ using Type = unsigned fract;
+ static constexpr int EXTRA_STEPS = 1;
+};
+
+template <> struct SqrtConfig<unsigned long fract> {
+ using Type = unsigned long fract;
+ static constexpr int EXTRA_STEPS = 2;
+};
+
+template <>
+struct SqrtConfig<unsigned short accum> : SqrtConfig<unsigned fract> {};
+
+template <>
+struct SqrtConfig<unsigned accum> : SqrtConfig<unsigned long fract> {};
+
+// TODO: unsigned long accum type is 64-bit, and will need 64-bit fract type.
+// Probably we will use DyadicFloat<64> for intermediate computations instead.
+
+// Linear approximation for the initial values, with errors bounded by:
+// max(1.5 * 2^-11, eps)
+// Generated with Sollya:
+// > for i from 4 to 15 do {
+// P = fpminimax(sqrt(x), 1, [|8, 8|], [i * 2^-4, (i + 1)*2^-4],
+// fixed, absolute);
+// print("{", coeff(P, 1), "uhr,", coeff(P, 0), "uhr},");
+// };
+// Clang is having issues with this array:
+// static constexpr unsigned short fract SQRT_FIRST_APPROX[12][2] = {
+// {0x1.e8p-1uhr, 0x1.0cp-2uhr}, {0x1.bap-1uhr, 0x1.28p-2uhr},
+// {0x1.94p-1uhr, 0x1.44p-2uhr}, {0x1.74p-1uhr, 0x1.6p-2uhr},
+// {0x1.6p-1uhr, 0x1.74p-2uhr}, {0x1.4ep-1uhr, 0x1.88p-2uhr},
+// {0x1.3ep-1uhr, 0x1.9cp-2uhr}, {0x1.32p-1uhr, 0x1.acp-2uhr},
+// {0x1.22p-1uhr, 0x1.c4p-2uhr}, {0x1.18p-1uhr, 0x1.d4p-2uhr},
+// {0x1.08p-1uhr, 0x1.fp-2uhr}, {0x1.04p-1uhr, 0x1.f8p-2uhr},
+// };
+// We are using their storage type instead.
+// TODO(https://github.com/llvm/llvm-project/issues/83050): Use fixed point
+// array when the bug is fixed.
+static constexpr uint8_t SQRT_FIRST_APPROX[12][2] = {
+ {244, 67}, {221, 74}, {202, 81}, {186, 88}, {176, 93}, {167, 98},
+ {159, 103}, {153, 107}, {145, 113}, {140, 117}, {132, 124}, {130, 126},
+};
+
+} // namespace internal
+
+template <typename T>
+LIBC_INLINE constexpr cpp::enable_if_t<cpp::is_fixed_point_v<T>, T> sqrt(T x) {
+ using BitType = typename FXRep<T>::StorageType;
+ BitType x_bit = cpp::bit_cast<BitType>(x);
+
+ if (LIBC_UNLIKELY(x_bit == 0))
+ return FXRep<T>::ZERO();
+
+ int leading_zeros = cpp::countl_zero(x_bit);
+ constexpr int STORAGE_LENGTH = sizeof(BitType) * CHAR_BIT;
+ constexpr int EXP_ADJUSTMENT = STORAGE_LENGTH - FXRep<T>::FRACTION_LEN - 1;
+ // x_exp is the real exponent of the leading bit of x.
+ int x_exp = EXP_ADJUSTMENT - leading_zeros;
+ int shift = EXP_ADJUSTMENT - 1 - (x_exp & (~1));
+ // Normalize.
+ x_bit <<= shift;
+ using FracType = typename internal::SqrtConfig<T>::Type;
+ FracType x_frac = cpp::bit_cast<FracType>(x_bit);
+
+ // Use use Newton method to approximate sqrt(a):
+ // x_{n + 1} = 1/2 (x_n + a / x_n)
+ // For the initial values, we choose x_0
+
+ // Use the leading 4 bits to do look up for sqrt(x).
+ int index = (x_bit >> (STORAGE_LENGTH - 4)) - 4;
+ FracType a = static_cast<FracType>(cpp::bit_cast<unsigned short fract>(
+ internal::SQRT_FIRST_APPROX[index][0]));
+ FracType b = static_cast<FracType>(cpp::bit_cast<unsigned short fract>(
+ internal::SQRT_FIRST_APPROX[index][1]));
+
+ // Initial approximation step.
+ // Estimated error bounds: | r - sqrt(x_frac) | < max(1.5 * 2^-11, eps).
+ FracType r = a * x_frac + b;
+
+ // Further Newton-method iterations for square-root:
+ // x_{n + 1} = 0.5 * (x_n + a / x_n)
+ // We distribute and do the multiplication by 0.5 first to avoid overflow.
+ // TODO: Investigate the performance and accuracy of using division-free
+ // iterations from:
+ // Blanchard, J. D. and Chamberland, M., "Newton's Method Without Division",
+ // The American Mathematical Monthly (2023).
+ // https://chamberland.math.grinnell.edu/papers/newton.pdf
+ for (int i = 0; i < internal::SqrtConfig<T>::EXTRA_STEPS; ++i) {
+ r = (r >> 1) + (x_frac >> 1) / r;
+ }
+
+ int r_exp = (x_exp >> 1);
+ int shift_back = EXP_ADJUSTMENT - r_exp;
+
+ // Re-scaling
+ r >>= shift_back;
+
+ // Return result.
+ return cpp::bit_cast<T>(r);
+}
+
+} // namespace LIBC_NAMESPACE::fixed_point
+
+#endif // LIBC_COMPILER_HAS_FIXED_POINT
+
+#endif // LLVM_LIBC_SRC___SUPPORT_FIXEDPOINT_SQRT_H
diff --git a/libc/src/stdfix/CMakeLists.txt b/libc/src/stdfix/CMakeLists.txt
index 6e2ed1bdfeafe7..cb2134fe33cf9c 100644
--- a/libc/src/stdfix/CMakeLists.txt
+++ b/libc/src/stdfix/CMakeLists.txt
@@ -17,6 +17,21 @@ foreach(suffix IN ITEMS hr r lr hk k lk)
)
endforeach()
+foreach(suffix IN ITEMS uhr ur ulr uhk uk)
+ add_entrypoint_object(
+ sqrt${suffix}
+ HDRS
+ sqrt${suffix}.h
+ SRCS
+ sqrt${suffix}.cpp
+ COMPILE_OPTIONS
+ -O3
+ -ffixed-point
+ DEPENDS
+ libc.src.__support.fixed_point.sqrt
+ )
+endforeach()
+
foreach(suffix IN ITEMS hr r lr hk k lk uhr ur ulr uhk uk ulk)
add_entrypoint_object(
round${suffix}
diff --git a/libc/src/stdfix/sqrtuhk.cpp b/libc/src/stdfix/sqrtuhk.cpp
new file mode 100644
index 00000000000000..e8dc842c8a9980
--- /dev/null
+++ b/libc/src/stdfix/sqrtuhk.cpp
@@ -0,0 +1,19 @@
+//===-- Implementation of sqrtuhk 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 "sqrtuhk.h"
+#include "src/__support/common.h"
+#include "src/__support/fixed_point/sqrt.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(unsigned short accum, sqrtuhk, (unsigned short accum x)) {
+ return fixed_point::sqrt(x);
+}
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/stdfix/sqrtuhk.h b/libc/src/stdfix/sqrtuhk.h
new file mode 100644
index 00000000000000..80000a0079696d
--- /dev/null
+++ b/libc/src/stdfix/sqrtuhk.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for sqrtuhk -----------------------*- 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_STDFIX_SQRTUHK_H
+#define LLVM_LIBC_SRC_STDFIX_SQRTUHK_H
+
+#include "include/llvm-libc-macros/stdfix-macros.h"
+
+namespace LIBC_NAMESPACE {
+
+unsigned short accum sqrtuhk(unsigned short accum x);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_STDFIX_SQRTUHK_H
diff --git a/libc/src/stdfix/sqrtuhr.cpp b/libc/src/stdfix/sqrtuhr.cpp
new file mode 100644
index 00000000000000..6bba07aa20d595
--- /dev/null
+++ b/libc/src/stdfix/sqrtuhr.cpp
@@ -0,0 +1,19 @@
+//===-- Implementation of sqrtuhr 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 "sqrtuhr.h"
+#include "src/__support/common.h"
+#include "src/__support/fixed_point/sqrt.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(unsigned short fract, sqrtuhr, (unsigned short fract x)) {
+ return fixed_point::sqrt(x);
+}
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/stdfix/sqrtuhr.h b/libc/src/stdfix/sqrtuhr.h
new file mode 100644
index 00000000000000..fd95f0924e8d48
--- /dev/null
+++ b/libc/src/stdfix/sqrtuhr.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for sqrtuhr -----------------------*- 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_STDFIX_SQRTUHR_H
+#define LLVM_LIBC_SRC_STDFIX_SQRTUHR_H
+
+#include "include/llvm-libc-macros/stdfix-macros.h"
+
+namespace LIBC_NAMESPACE {
+
+unsigned short fract sqrtuhr(unsigned short fract x);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_STDFIX_SQRTUHR_H
diff --git a/libc/src/stdfix/sqrtuk.cpp b/libc/src/stdfix/sqrtuk.cpp
new file mode 100644
index 00000000000000..6e5d8118c83b73
--- /dev/null
+++ b/libc/src/stdfix/sqrtuk.cpp
@@ -0,0 +1,19 @@
+//===-- Implementation of sqrtuk 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 "sqrtuk.h"
+#include "src/__support/common.h"
+#include "src/__support/fixed_point/sqrt.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(unsigned accum, sqrtuk, (unsigned accum x)) {
+ return fixed_point::sqrt(x);
+}
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/stdfix/sqrtuk.h b/libc/src/stdfix/sqrtuk.h
new file mode 100644
index 00000000000000..04d0adadde9ad2
--- /dev/null
+++ b/libc/src/stdfix/sqrtuk.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for sqrtuk ------------------------*- 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_STDFIX_SQRTUK_H
+#define LLVM_LIBC_SRC_STDFIX_SQRTUK_H
+
+#include "include/llvm-libc-macros/stdfix-macros.h"
+
+namespace LIBC_NAMESPACE {
+
+unsigned accum sqrtuk(unsigned accum x);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_STDFIX_SQRTUK_H
diff --git a/libc/src/stdfix/sqrtulr.cpp b/libc/src/stdfix/sqrtulr.cpp
new file mode 100644
index 00000000000000..c9e5cd51f66bc5
--- /dev/null
+++ b/libc/src/stdfix/sqrtulr.cpp
@@ -0,0 +1,19 @@
+//===-- Implementation of sqrtulr 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 "sqrtulr.h"
+#include "src/__support/common.h"
+#include "src/__support/fixed_point/sqrt.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(unsigned long fract, sqrtulr, (unsigned long fract x)) {
+ return fixed_point::sqrt(x);
+}
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/stdfix/sqrtulr.h b/libc/src/stdfix/sqrtulr.h
new file mode 100644
index 00000000000000..284adaaf35bf59
--- /dev/null
+++ b/libc/src/stdfix/sqrtulr.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for sqrtulr -----------------------*- 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_STDFIX_SQRTULR_H
+#define LLVM_LIBC_SRC_STDFIX_SQRTULR_H
+
+#include "include/llvm-libc-macros/stdfix-macros.h"
+
+namespace LIBC_NAMESPACE {
+
+unsigned long fract sqrtulr(unsigned long fract x);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_STDFIX_SQRTULR_H
diff --git a/libc/src/stdfix/sqrtur.cpp b/libc/src/stdfix/sqrtur.cpp
new file mode 100644
index 00000000000000..ac5be84910849f
--- /dev/null
+++ b/libc/src/stdfix/sqrtur.cpp
@@ -0,0 +1,19 @@
+//===-- Implementation of sqrtur 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 "sqrtur.h"
+#include "src/__support/common.h"
+#include "src/__support/fixed_point/sqrt.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(unsigned fract, sqrtur, (unsigned fract x)) {
+ return fixed_point::sqrt(x);
+}
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/stdfix/sqrtur.h b/libc/src/stdfix/sqrtur.h
new file mode 100644
index 00000000000000..df9dfe5a0bf39e
--- /dev/null
+++ b/libc/src/stdfix/sqrtur.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for sqrtur ------------------------*- 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_STDFIX_SQRTUR_H
+#define LLVM_LIBC_SRC_STDFIX_SQRTUR_H
+
+#include "include/llvm-libc-macros/stdfix-macros.h"
+
+namespace LIBC_NAMESPACE {
+
+unsigned fract sqrtur(unsigned fract x);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_STDFIX_SQRTUR_H
diff --git a/libc/test/src/stdfix/CMakeLists.txt b/libc/test/src/stdfix/CMakeLists.txt
index b6e0256bb68800..4140b5b29f3b3c 100644
--- a/libc/test/src/stdfix/CMakeLists.txt
+++ b/libc/test/src/stdfix/CMakeLists.txt
@@ -22,6 +22,28 @@ foreach(suffix IN ITEMS hr r lr hk k lk)
)
endforeach()
+foreach(suffix IN ITEMS uhr ur ulr uhk uk)
+ add_libc_test(
+ sqrt${suffix}_test
+ SUITE
+ libc-stdfix-tests
+ HDRS
+ SqrtTest.h
+ SRCS
+ sqrt${suffix}_test.cpp
+ COMPILE_OPTIONS
+ -O3
+ -ffixed-point
+ DEPENDS
+ libc.src.stdfix.sqrt${suffix}
+ libc.src.__support.CPP.bit
+ libc.src.__support.fixed_point.fx_rep
+ libc.src.__support.fixed_point.sqrt
+ libc.src.__support.FPUtil.basic_operations
+ libc.src.__support.FPUtil.sqrt
+ )
+endforeach()
+
foreach(suffix IN ITEMS hr r lr hk k lk uhr ur ulr uhk uk ulk)
add_libc_test(
round${suffix}_test
diff --git a/libc/test/src/stdfix/SqrtTest.h b/libc/test/src/stdfix/SqrtTest.h
new file mode 100644
index 00000000000000..628be0deb770fb
--- /dev/null
+++ b/libc/test/src/stdfix/SqrtTest.h
@@ -0,0 +1,66 @@
+//===-- Utility class to test fixed-point sqrt ------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "test/UnitTest/Test.h"
+
+#include "src/__support/CPP/bit.h"...
[truncated]
``````````
</details>
https://github.com/llvm/llvm-project/pull/83042
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