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[libc][stdbit] implement stdc_first_leading_zero (C23) (#81340)
1 parent ab70251 commit d2d6b36

23 files changed

+388
-2
lines changed

‎libc/config/linux/x86_64/entrypoints.txt‎

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@@ -112,6 +112,11 @@ set(TARGET_LIBC_ENTRYPOINTS
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libc.src.stdbit.stdc_trailing_ones_ui
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libc.src.stdbit.stdc_trailing_ones_ul
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libc.src.stdbit.stdc_trailing_ones_ull
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libc.src.stdbit.stdc_first_leading_zero_uc
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libc.src.stdbit.stdc_first_leading_zero_us
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libc.src.stdbit.stdc_first_leading_zero_ui
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libc.src.stdbit.stdc_first_leading_zero_ul
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libc.src.stdbit.stdc_first_leading_zero_ull
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# stdlib.h entrypoints
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libc.src.stdlib.abs

‎libc/include/llvm-libc-macros/stdbit-macros.h‎

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@@ -71,6 +71,21 @@ inline unsigned stdc_trailing_ones(unsigned long x) {
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inline unsigned stdc_trailing_ones(unsigned long long x) {
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return stdc_trailing_ones_ull(x);
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}
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inline unsigned stdc_first_leading_zero(unsigned char x) {
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return stdc_first_leading_zero_uc(x);
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}
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inline unsigned stdc_first_leading_zero(unsigned short x) {
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return stdc_first_leading_zero_us(x);
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}
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inline unsigned stdc_first_leading_zero(unsigned x) {
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return stdc_first_leading_zero_ui(x);
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}
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inline unsigned stdc_first_leading_zero(unsigned long x) {
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return stdc_first_leading_zero_ul(x);
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}
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inline unsigned stdc_first_leading_zero(unsigned long long x) {
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return stdc_first_leading_zero_ull(x);
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}
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#else
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#define stdc_leading_zeros(x) \
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_Generic((x), \
@@ -100,6 +115,13 @@ inline unsigned stdc_trailing_ones(unsigned long long x) {
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unsigned: stdc_trailing_ones_ui, \
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unsigned long: stdc_trailing_ones_ul, \
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unsigned long long: stdc_trailing_ones_ull)(x)
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#define stdc_first_leading_zero(x) \
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_Generic((x), \
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unsigned char: stdc_first_leading_zero_uc, \
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unsigned short: stdc_first_leading_zero_us, \
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unsigned: stdc_first_leading_zero_ui, \
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unsigned long: stdc_first_leading_zero_ul, \
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unsigned long long: stdc_first_leading_zero_ull)(x)
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#endif // __cplusplus
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#endif // __LLVM_LIBC_MACROS_STDBIT_MACROS_H

‎libc/spec/stdc.td‎

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@@ -780,7 +780,8 @@ def StdC : StandardSpec<"stdc"> {
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Macro<"stdc_leading_zeros">,
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Macro<"stdc_leading_ones">,
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Macro<"stdc_trailing_zeros">,
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Macro<"stdc_trailing_ones">
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Macro<"stdc_trailing_ones">,
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Macro<"stdc_first_leading_zero">
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], // Macros
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[], // Types
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[], // Enumerations
@@ -804,7 +805,12 @@ def StdC : StandardSpec<"stdc"> {
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FunctionSpec<"stdc_trailing_ones_us", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedShortType>]>,
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FunctionSpec<"stdc_trailing_ones_ui", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedIntType>]>,
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FunctionSpec<"stdc_trailing_ones_ul", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedLongType>]>,
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FunctionSpec<"stdc_trailing_ones_ull", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedLongLongType>]>
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FunctionSpec<"stdc_trailing_ones_ull", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedLongLongType>]>,
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FunctionSpec<"stdc_first_leading_zero_uc", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedCharType>]>,
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FunctionSpec<"stdc_first_leading_zero_us", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedShortType>]>,
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FunctionSpec<"stdc_first_leading_zero_ui", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedIntType>]>,
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FunctionSpec<"stdc_first_leading_zero_ul", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedLongType>]>,
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FunctionSpec<"stdc_first_leading_zero_ull", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedLongLongType>]>
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] // Functions
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>;
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‎libc/src/__support/CPP/bit.h‎

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@@ -238,6 +238,36 @@ LIBC_INLINE constexpr To bit_or_static_cast(const From &from) {
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}
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}
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#define SPECIALIZE_FLZ(NAME, TYPE, BUILTIN) \
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template <> [[nodiscard]] LIBC_INLINE constexpr int NAME<TYPE>(TYPE value) { \
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static_assert(cpp::is_unsigned_v<TYPE>); \
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return value == cpp::numeric_limits<TYPE>::max() \
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? 0 \
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: BUILTIN(static_cast<TYPE>(~value)) + 1; \
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}
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template <typename T, typename = cpp::enable_if_t<cpp::is_unsigned_v<T>>>
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[[nodiscard]] LIBC_INLINE constexpr int first_leading_zero(T value) {
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return value == cpp::numeric_limits<T>::max()
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? 0
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: countl_zero(static_cast<T>(~value)) + 1;
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}
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#if LIBC_HAS_BUILTIN(__builtin_clzs)
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SPECIALIZE_FLZ(first_leading_zero, unsigned short, __builtin_clzs)
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#endif
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#if LIBC_HAS_BUILTIN(__builtin_clz)
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SPECIALIZE_FLZ(first_leading_zero, unsigned int, __builtin_clz)
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#endif
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#if LIBC_HAS_BUILTIN(__builtin_clzl)
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SPECIALIZE_FLZ(first_leading_zero, unsigned long, __builtin_clzl)
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#endif
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#if LIBC_HAS_BUILTIN(__builtin_clzll)
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SPECIALIZE_FLZ(first_leading_zero, unsigned long long, __builtin_clzll)
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#endif
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#undef SPECIALIZE_FLZ
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} // namespace LIBC_NAMESPACE::cpp
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#endif // LLVM_LIBC_SRC___SUPPORT_CPP_BIT_H

‎libc/src/stdbit/CMakeLists.txt‎

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@@ -3,6 +3,7 @@ set(prefixes
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leading_ones
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trailing_zeros
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trailing_ones
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first_leading_zero
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)
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set(suffixes c s i l ll)
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foreach(prefix IN LISTS prefixes)

‎libc/src/stdbit/stdc_first_leading_zero_uc.cpp‎

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//===-- Implementation of stdc_first_leading_zero_uc ----------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "src/stdbit/stdc_first_leading_zero_uc.h"
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#include "src/__support/CPP/bit.h"
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#include "src/__support/common.h"
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namespace LIBC_NAMESPACE {
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LLVM_LIBC_FUNCTION(unsigned, stdc_first_leading_zero_uc,
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(unsigned char value)) {
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return static_cast<unsigned>(cpp::first_leading_zero(value));
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}
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} // namespace LIBC_NAMESPACE

‎libc/src/stdbit/stdc_first_leading_zero_uc.h‎

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//===-- Implementation header for stdc_first_leading_zero_uc ----*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ZERO_UC_H
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#define LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ZERO_UC_H
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namespace LIBC_NAMESPACE {
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unsigned stdc_first_leading_zero_uc(unsigned char value);
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} // namespace LIBC_NAMESPACE
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#endif // LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ZERO_UC_H

‎libc/src/stdbit/stdc_first_leading_zero_ui.cpp‎

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@@ -0,0 +1,20 @@
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//===-- Implementation of stdc_first_leading_zero_ui ----------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "src/stdbit/stdc_first_leading_zero_ui.h"
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#include "src/__support/CPP/bit.h"
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#include "src/__support/common.h"
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namespace LIBC_NAMESPACE {
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LLVM_LIBC_FUNCTION(unsigned, stdc_first_leading_zero_ui, (unsigned value)) {
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return static_cast<unsigned>(cpp::first_leading_zero(value));
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}
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} // namespace LIBC_NAMESPACE

‎libc/src/stdbit/stdc_first_leading_zero_ui.h‎

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@@ -0,0 +1,18 @@
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//===-- Implementation header for stdc_first_leading_zero_ui ----*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ZERO_UI_H
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#define LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ZERO_UI_H
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namespace LIBC_NAMESPACE {
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unsigned stdc_first_leading_zero_ui(unsigned value);
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} // namespace LIBC_NAMESPACE
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#endif // LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ZERO_UI_H

‎libc/src/stdbit/stdc_first_leading_zero_ul.cpp‎

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@@ -0,0 +1,21 @@
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//===-- Implementation of stdc_first_leading_zero_ul ----------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "src/stdbit/stdc_first_leading_zero_ul.h"
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#include "src/__support/CPP/bit.h"
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#include "src/__support/common.h"
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namespace LIBC_NAMESPACE {
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LLVM_LIBC_FUNCTION(unsigned, stdc_first_leading_zero_ul,
17+
(unsigned long value)) {
18+
return static_cast<unsigned>(cpp::first_leading_zero(value));
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}
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} // namespace LIBC_NAMESPACE

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