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[libc][stdbit] implement stdc_first_leading_zero (C23) (#81340)

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This commit is contained in:
Nick Desaulniers 2024-02-12 08:31:53 -08:00 committed by GitHub
parent ab702513f1
commit d2d6b368a1
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GPG Key ID: B5690EEEBB952194
23 changed files with 388 additions and 2 deletions
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5
libc/config/linux/x86_64/entrypoints.txt
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@ -112,6 +112,11 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.stdbit.stdc_trailing_ones_ui
libc.src.stdbit.stdc_trailing_ones_ul
libc.src.stdbit.stdc_trailing_ones_ull
libc.src.stdbit.stdc_first_leading_zero_uc
libc.src.stdbit.stdc_first_leading_zero_us
libc.src.stdbit.stdc_first_leading_zero_ui
libc.src.stdbit.stdc_first_leading_zero_ul
libc.src.stdbit.stdc_first_leading_zero_ull
# stdlib.h entrypoints
libc.src.stdlib.abs

22
libc/include/llvm-libc-macros/stdbit-macros.h
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@ -71,6 +71,21 @@ inline unsigned stdc_trailing_ones(unsigned long x) {
inline unsigned stdc_trailing_ones(unsigned long long x) {
return stdc_trailing_ones_ull(x);
}
inline unsigned stdc_first_leading_zero(unsigned char x) {
return stdc_first_leading_zero_uc(x);
}
inline unsigned stdc_first_leading_zero(unsigned short x) {
return stdc_first_leading_zero_us(x);
}
inline unsigned stdc_first_leading_zero(unsigned x) {
return stdc_first_leading_zero_ui(x);
}
inline unsigned stdc_first_leading_zero(unsigned long x) {
return stdc_first_leading_zero_ul(x);
}
inline unsigned stdc_first_leading_zero(unsigned long long x) {
return stdc_first_leading_zero_ull(x);
}
#else
#define stdc_leading_zeros(x) \
_Generic((x), \
@ -100,6 +115,13 @@ inline unsigned stdc_trailing_ones(unsigned long long x) {
unsigned: stdc_trailing_ones_ui, \
unsigned long: stdc_trailing_ones_ul, \
unsigned long long: stdc_trailing_ones_ull)(x)
#define stdc_first_leading_zero(x) \
_Generic((x), \
unsigned char: stdc_first_leading_zero_uc, \
unsigned short: stdc_first_leading_zero_us, \
unsigned: stdc_first_leading_zero_ui, \
unsigned long: stdc_first_leading_zero_ul, \
unsigned long long: stdc_first_leading_zero_ull)(x)
#endif // __cplusplus
#endif // __LLVM_LIBC_MACROS_STDBIT_MACROS_H

10
libc/spec/stdc.td
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@ -780,7 +780,8 @@ def StdC : StandardSpec<"stdc"> {
Macro<"stdc_leading_zeros">,
Macro<"stdc_leading_ones">,
Macro<"stdc_trailing_zeros">,
Macro<"stdc_trailing_ones">
Macro<"stdc_trailing_ones">,
Macro<"stdc_first_leading_zero">
], // Macros
[], // Types
[], // Enumerations
@ -804,7 +805,12 @@ def StdC : StandardSpec<"stdc"> {
FunctionSpec<"stdc_trailing_ones_us", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedShortType>]>,
FunctionSpec<"stdc_trailing_ones_ui", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedIntType>]>,
FunctionSpec<"stdc_trailing_ones_ul", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedLongType>]>,
FunctionSpec<"stdc_trailing_ones_ull", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedLongLongType>]>
FunctionSpec<"stdc_trailing_ones_ull", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedLongLongType>]>,
FunctionSpec<"stdc_first_leading_zero_uc", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedCharType>]>,
FunctionSpec<"stdc_first_leading_zero_us", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedShortType>]>,
FunctionSpec<"stdc_first_leading_zero_ui", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedIntType>]>,
FunctionSpec<"stdc_first_leading_zero_ul", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedLongType>]>,
FunctionSpec<"stdc_first_leading_zero_ull", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedLongLongType>]>
] // Functions
>;

30
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) {
}
}
#define SPECIALIZE_FLZ(NAME, TYPE, BUILTIN) \
template <> [[nodiscard]] LIBC_INLINE constexpr int NAME<TYPE>(TYPE value) { \
static_assert(cpp::is_unsigned_v<TYPE>); \
return value == cpp::numeric_limits<TYPE>::max() \
? 0 \
: BUILTIN(static_cast<TYPE>(~value)) + 1; \
}
template <typename T, typename = cpp::enable_if_t<cpp::is_unsigned_v<T>>>
[[nodiscard]] LIBC_INLINE constexpr int first_leading_zero(T value) {
return value == cpp::numeric_limits<T>::max()
? 0
: countl_zero(static_cast<T>(~value)) + 1;
}
#if LIBC_HAS_BUILTIN(__builtin_clzs)
SPECIALIZE_FLZ(first_leading_zero, unsigned short, __builtin_clzs)
#endif
#if LIBC_HAS_BUILTIN(__builtin_clz)
SPECIALIZE_FLZ(first_leading_zero, unsigned int, __builtin_clz)
#endif
#if LIBC_HAS_BUILTIN(__builtin_clzl)
SPECIALIZE_FLZ(first_leading_zero, unsigned long, __builtin_clzl)
#endif
#if LIBC_HAS_BUILTIN(__builtin_clzll)
SPECIALIZE_FLZ(first_leading_zero, unsigned long long, __builtin_clzll)
#endif
#undef SPECIALIZE_FLZ
} // namespace LIBC_NAMESPACE::cpp
#endif // LLVM_LIBC_SRC___SUPPORT_CPP_BIT_H

1
libc/src/stdbit/CMakeLists.txt
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@ -3,6 +3,7 @@ set(prefixes
leading_ones
trailing_zeros
trailing_ones
first_leading_zero
)
set(suffixes c s i l ll)
foreach(prefix IN LISTS prefixes)

21
libc/src/stdbit/stdc_first_leading_zero_uc.cpp Normal file
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@ -0,0 +1,21 @@
//===-- Implementation of stdc_first_leading_zero_uc ----------------------===//
//
// 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/stdbit/stdc_first_leading_zero_uc.h"
#include "src/__support/CPP/bit.h"
#include "src/__support/common.h"
namespace LIBC_NAMESPACE {
LLVM_LIBC_FUNCTION(unsigned, stdc_first_leading_zero_uc,
(unsigned char value)) {
return static_cast<unsigned>(cpp::first_leading_zero(value));
}
} // namespace LIBC_NAMESPACE

18
libc/src/stdbit/stdc_first_leading_zero_uc.h Normal file
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@ -0,0 +1,18 @@
//===-- Implementation header for stdc_first_leading_zero_uc ----*- 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_STDBIT_STDC_FIRST_LEADING_ZERO_UC_H
#define LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ZERO_UC_H
namespace LIBC_NAMESPACE {
unsigned stdc_first_leading_zero_uc(unsigned char value);
} // namespace LIBC_NAMESPACE
#endif // LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ZERO_UC_H

20
libc/src/stdbit/stdc_first_leading_zero_ui.cpp Normal file
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@ -0,0 +1,20 @@
//===-- Implementation of stdc_first_leading_zero_ui ----------------------===//
//
// 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/stdbit/stdc_first_leading_zero_ui.h"
#include "src/__support/CPP/bit.h"
#include "src/__support/common.h"
namespace LIBC_NAMESPACE {
LLVM_LIBC_FUNCTION(unsigned, stdc_first_leading_zero_ui, (unsigned value)) {
return static_cast<unsigned>(cpp::first_leading_zero(value));
}
} // namespace LIBC_NAMESPACE

18
libc/src/stdbit/stdc_first_leading_zero_ui.h Normal file
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@ -0,0 +1,18 @@
//===-- Implementation header for stdc_first_leading_zero_ui ----*- 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_STDBIT_STDC_FIRST_LEADING_ZERO_UI_H
#define LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ZERO_UI_H
namespace LIBC_NAMESPACE {
unsigned stdc_first_leading_zero_ui(unsigned value);
} // namespace LIBC_NAMESPACE
#endif // LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ZERO_UI_H

21
libc/src/stdbit/stdc_first_leading_zero_ul.cpp Normal file
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@ -0,0 +1,21 @@
//===-- Implementation of stdc_first_leading_zero_ul ----------------------===//
//
// 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/stdbit/stdc_first_leading_zero_ul.h"
#include "src/__support/CPP/bit.h"
#include "src/__support/common.h"
namespace LIBC_NAMESPACE {
LLVM_LIBC_FUNCTION(unsigned, stdc_first_leading_zero_ul,
(unsigned long value)) {
return static_cast<unsigned>(cpp::first_leading_zero(value));
}
} // namespace LIBC_NAMESPACE

18
libc/src/stdbit/stdc_first_leading_zero_ul.h Normal file
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@ -0,0 +1,18 @@
//===-- Implementation header for stdc_first_leading_zero_ul ----*- 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_STDBIT_STDC_FIRST_LEADING_ZERO_UL_H
#define LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ZERO_UL_H
namespace LIBC_NAMESPACE {
unsigned stdc_first_leading_zero_ul(unsigned long value);
} // namespace LIBC_NAMESPACE
#endif // LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ZERO_UL_H

21
libc/src/stdbit/stdc_first_leading_zero_ull.cpp Normal file
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@ -0,0 +1,21 @@
//===-- Implementation of stdc_first_leading_zero_ull ---------------------===//
//
// 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/stdbit/stdc_first_leading_zero_ull.h"
#include "src/__support/CPP/bit.h"
#include "src/__support/common.h"
namespace LIBC_NAMESPACE {
LLVM_LIBC_FUNCTION(unsigned, stdc_first_leading_zero_ull,
(unsigned long long value)) {
return static_cast<unsigned>(cpp::first_leading_zero(value));
}
} // namespace LIBC_NAMESPACE

18
libc/src/stdbit/stdc_first_leading_zero_ull.h Normal file
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@ -0,0 +1,18 @@
//===-- Implementation header for stdc_first_leading_zero_ull ---*- 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_STDBIT_STDC_FIRST_LEADING_ZERO_ULL_H
#define LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ZERO_ULL_H
namespace LIBC_NAMESPACE {
unsigned stdc_first_leading_zero_ull(unsigned long long value);
} // namespace LIBC_NAMESPACE
#endif // LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ZERO_ULL_H

21
libc/src/stdbit/stdc_first_leading_zero_us.cpp Normal file
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@ -0,0 +1,21 @@
//===-- Implementation of stdc_first_leading_zero_us ----------------------===//
//
// 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/stdbit/stdc_first_leading_zero_us.h"
#include "src/__support/CPP/bit.h"
#include "src/__support/common.h"
namespace LIBC_NAMESPACE {
LLVM_LIBC_FUNCTION(unsigned, stdc_first_leading_zero_us,
(unsigned short value)) {
return static_cast<unsigned>(cpp::first_leading_zero(value));
}
} // namespace LIBC_NAMESPACE

18
libc/src/stdbit/stdc_first_leading_zero_us.h Normal file
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@ -0,0 +1,18 @@
//===-- Implementation header for stdc_first_leading_zero_us ----*- 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_STDBIT_STDC_FIRST_LEADING_ZERO_US_H
#define LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ZERO_US_H
namespace LIBC_NAMESPACE {
unsigned stdc_first_leading_zero_us(unsigned short value);
} // namespace LIBC_NAMESPACE
#endif // LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ZERO_US_H

15
libc/test/include/stdbit_test.cpp
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@ -43,6 +43,13 @@ unsigned stdc_trailing_ones_us(unsigned short) noexcept { return 0xDBU; }
unsigned stdc_trailing_ones_ui(unsigned) noexcept { return 0xDCU; }
unsigned stdc_trailing_ones_ul(unsigned long) noexcept { return 0xDDU; }
unsigned stdc_trailing_ones_ull(unsigned long long) noexcept { return 0xDFU; }
unsigned stdc_first_leading_zero_uc(unsigned char) noexcept { return 0xEAU; }
unsigned stdc_first_leading_zero_us(unsigned short) noexcept { return 0xEBU; }
unsigned stdc_first_leading_zero_ui(unsigned) noexcept { return 0xECU; }
unsigned stdc_first_leading_zero_ul(unsigned long) noexcept { return 0xEDU; }
unsigned stdc_first_leading_zero_ull(unsigned long long) noexcept {
return 0xEFU;
}
}
#include "include/llvm-libc-macros/stdbit-macros.h"
@ -78,3 +85,11 @@ TEST(LlvmLibcStdbitTest, TypeGenericMacroTrailingOnes) {
EXPECT_EQ(stdc_trailing_ones(0UL), 0xDDU);
EXPECT_EQ(stdc_trailing_ones(0ULL), 0xDFU);
}
TEST(LlvmLibcStdbitTest, TypeGenericMacroFirstLeadingZero) {
EXPECT_EQ(stdc_first_leading_zero(static_cast<unsigned char>(0U)), 0xEAU);
EXPECT_EQ(stdc_first_leading_zero(static_cast<unsigned short>(0U)), 0xEBU);
EXPECT_EQ(stdc_first_leading_zero(0U), 0xECU);
EXPECT_EQ(stdc_first_leading_zero(0UL), 0xEDU);
EXPECT_EQ(stdc_first_leading_zero(0ULL), 0xEFU);
}

7
libc/test/src/__support/CPP/bit_test.cpp
View File

@ -206,4 +206,11 @@ TEST(LlvmLibcBitTest, Rotr) {
rotr<uint64_t>(0x12345678deadbeefULL, -19));
}
TYPED_TEST(LlvmLibcBitTest, FirstLeadingZero, UnsignedTypes) {
EXPECT_EQ(first_leading_zero<T>(cpp::numeric_limits<T>::max()), 0);
for (int i = 0U; i != cpp::numeric_limits<T>::digits; ++i)
EXPECT_EQ(first_leading_zero<T>(~(T(1) << i)),
cpp::numeric_limits<T>::digits - i);
}
} // namespace LIBC_NAMESPACE::cpp

1
libc/test/src/stdbit/CMakeLists.txt
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@ -5,6 +5,7 @@ set(prefixes
leading_ones
trailing_zeros
trailing_ones
first_leading_zero
)
set(suffixes c s i l ll)
foreach(prefix IN LISTS prefixes)

21
libc/test/src/stdbit/stdc_first_leading_zero_uc_test.cpp Normal file
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@ -0,0 +1,21 @@
//===-- Unittests for stdc_first_leading_zero_uc --------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "src/__support/CPP/limits.h"
#include "src/stdbit/stdc_first_leading_zero_uc.h"
#include "test/UnitTest/Test.h"
TEST(LlvmLibcStdcFirstLeadingZeroUcTest, ALL) {
EXPECT_EQ(LIBC_NAMESPACE::stdc_first_leading_zero_uc(UCHAR_MAX), 0U);
}
TEST(LlvmLibcStdcFirstLeadingZeroUcTest, ZeroHot) {
for (unsigned i = 0U; i != UCHAR_WIDTH; ++i)
EXPECT_EQ(LIBC_NAMESPACE::stdc_first_leading_zero_uc(~(1U << i)),
UCHAR_WIDTH - i);
}

21
libc/test/src/stdbit/stdc_first_leading_zero_ui_test.cpp Normal file
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@ -0,0 +1,21 @@
//===-- Unittests for stdc_first_leading_zero_ui --------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "src/__support/CPP/limits.h"
#include "src/stdbit/stdc_first_leading_zero_ui.h"
#include "test/UnitTest/Test.h"
TEST(LlvmLibcStdcFirstLeadingZeroUiTest, ALL) {
EXPECT_EQ(LIBC_NAMESPACE::stdc_first_leading_zero_ui(UINT_MAX), 0U);
}
TEST(LlvmLibcStdcFirstLeadingZeroUiTest, ZeroHot) {
for (unsigned i = 0U; i != UINT_WIDTH; ++i)
EXPECT_EQ(LIBC_NAMESPACE::stdc_first_leading_zero_ui(~(1U << i)),
UINT_WIDTH - i);
}

21
libc/test/src/stdbit/stdc_first_leading_zero_ul_test.cpp Normal file
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@ -0,0 +1,21 @@
//===-- Unittests for stdc_first_leading_zero_ul --------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "src/__support/CPP/limits.h"
#include "src/stdbit/stdc_first_leading_zero_ul.h"
#include "test/UnitTest/Test.h"
TEST(LlvmLibcStdcFirstLeadingZeroUlTest, ALL) {
EXPECT_EQ(LIBC_NAMESPACE::stdc_first_leading_zero_ul(ULONG_MAX), 0U);
}
TEST(LlvmLibcStdcFirstLeadingZeroUlTest, ZeroHot) {
for (unsigned i = 0U; i != ULONG_WIDTH; ++i)
EXPECT_EQ(LIBC_NAMESPACE::stdc_first_leading_zero_ul(~(1UL << i)),
ULONG_WIDTH - i);
}

21
libc/test/src/stdbit/stdc_first_leading_zero_ull_test.cpp Normal file
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@ -0,0 +1,21 @@
//===-- Unittests for stdc_first_leading_zero_ull -------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "src/__support/CPP/limits.h"
#include "src/stdbit/stdc_first_leading_zero_ull.h"
#include "test/UnitTest/Test.h"
TEST(LlvmLibcStdcFirstLeadingZeroUllTest, ALL) {
EXPECT_EQ(LIBC_NAMESPACE::stdc_first_leading_zero_ull(ULLONG_MAX), 0U);
}
TEST(LlvmLibcStdcFirstLeadingZeroUllTest, ZeroHot) {
for (unsigned i = 0U; i != ULLONG_WIDTH; ++i)
EXPECT_EQ(LIBC_NAMESPACE::stdc_first_leading_zero_ull(~(1ULL << i)),
ULLONG_WIDTH - i);
}

21
libc/test/src/stdbit/stdc_first_leading_zero_us_test.cpp Normal file
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@ -0,0 +1,21 @@
//===-- Unittests for stdc_first_leading_zero_us --------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "src/__support/CPP/limits.h"
#include "src/stdbit/stdc_first_leading_zero_us.h"
#include "test/UnitTest/Test.h"
TEST(LlvmLibcStdcFirstLeadingZeroUsTest, ALL) {
EXPECT_EQ(LIBC_NAMESPACE::stdc_first_leading_zero_us(USHRT_MAX), 0U);
}
TEST(LlvmLibcStdcFirstLeadingZeroUsTest, ZeroHot) {
for (unsigned i = 0U; i != USHRT_WIDTH; ++i)
EXPECT_EQ(LIBC_NAMESPACE::stdc_first_leading_zero_us(~(1U << i)),
USHRT_WIDTH - i);
}