[libc-commits] [libc] [libc][stdbit] implement stdc_first_leading_one (C23) (PR #81502)
Nick Desaulniers via libc-commits
libc-commits at lists.llvm.org
Wed Feb 14 09:12:37 PST 2024
https://github.com/nickdesaulniers updated https://github.com/llvm/llvm-project/pull/81502
>From 1fabc28d9378cb0eedd86a9c545073d97c32efbe Mon Sep 17 00:00:00 2001
From: Nick Desaulniers <ndesaulniers at google.com>
Date: Mon, 12 Feb 2024 09:40:01 -0800
Subject: [PATCH 1/4] [libc][stdbit] implement stdc_first_leading_one (C23)
---
libc/config/linux/x86_64/entrypoints.txt | 5 +++
libc/docs/stdbit.rst | 40 +++++++++----------
libc/include/llvm-libc-macros/stdbit-macros.h | 22 ++++++++++
libc/spec/stdc.td | 10 ++++-
libc/src/__support/CPP/bit.h | 6 +++
libc/src/stdbit/CMakeLists.txt | 1 +
libc/src/stdbit/stdc_first_leading_one_uc.cpp | 20 ++++++++++
libc/src/stdbit/stdc_first_leading_one_uc.h | 18 +++++++++
libc/src/stdbit/stdc_first_leading_one_ui.cpp | 20 ++++++++++
libc/src/stdbit/stdc_first_leading_one_ui.h | 18 +++++++++
libc/src/stdbit/stdc_first_leading_one_ul.cpp | 20 ++++++++++
libc/src/stdbit/stdc_first_leading_one_ul.h | 18 +++++++++
.../src/stdbit/stdc_first_leading_one_ull.cpp | 21 ++++++++++
libc/src/stdbit/stdc_first_leading_one_ull.h | 18 +++++++++
libc/src/stdbit/stdc_first_leading_one_us.cpp | 21 ++++++++++
libc/src/stdbit/stdc_first_leading_one_us.h | 18 +++++++++
libc/test/include/stdbit_test.cpp | 15 +++++++
libc/test/src/__support/CPP/bit_test.cpp | 7 ++++
libc/test/src/stdbit/CMakeLists.txt | 1 +
.../stdbit/stdc_first_leading_one_uc_test.cpp | 21 ++++++++++
.../stdbit/stdc_first_leading_one_ui_test.cpp | 21 ++++++++++
.../stdbit/stdc_first_leading_one_ul_test.cpp | 21 ++++++++++
.../stdc_first_leading_one_ull_test.cpp | 21 ++++++++++
.../stdbit/stdc_first_leading_one_us_test.cpp | 21 ++++++++++
24 files changed, 382 insertions(+), 22 deletions(-)
create mode 100644 libc/src/stdbit/stdc_first_leading_one_uc.cpp
create mode 100644 libc/src/stdbit/stdc_first_leading_one_uc.h
create mode 100644 libc/src/stdbit/stdc_first_leading_one_ui.cpp
create mode 100644 libc/src/stdbit/stdc_first_leading_one_ui.h
create mode 100644 libc/src/stdbit/stdc_first_leading_one_ul.cpp
create mode 100644 libc/src/stdbit/stdc_first_leading_one_ul.h
create mode 100644 libc/src/stdbit/stdc_first_leading_one_ull.cpp
create mode 100644 libc/src/stdbit/stdc_first_leading_one_ull.h
create mode 100644 libc/src/stdbit/stdc_first_leading_one_us.cpp
create mode 100644 libc/src/stdbit/stdc_first_leading_one_us.h
create mode 100644 libc/test/src/stdbit/stdc_first_leading_one_uc_test.cpp
create mode 100644 libc/test/src/stdbit/stdc_first_leading_one_ui_test.cpp
create mode 100644 libc/test/src/stdbit/stdc_first_leading_one_ul_test.cpp
create mode 100644 libc/test/src/stdbit/stdc_first_leading_one_ull_test.cpp
create mode 100644 libc/test/src/stdbit/stdc_first_leading_one_us_test.cpp
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 75e39ae51fdb06..fc30bcf56665c7 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -117,6 +117,11 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.stdbit.stdc_first_leading_zero_ui
libc.src.stdbit.stdc_first_leading_zero_ul
libc.src.stdbit.stdc_first_leading_zero_ull
+ libc.src.stdbit.stdc_first_leading_one_uc
+ libc.src.stdbit.stdc_first_leading_one_us
+ libc.src.stdbit.stdc_first_leading_one_ui
+ libc.src.stdbit.stdc_first_leading_one_ul
+ libc.src.stdbit.stdc_first_leading_one_ull
# stdlib.h entrypoints
libc.src.stdlib.abs
diff --git a/libc/docs/stdbit.rst b/libc/docs/stdbit.rst
index 4f242d21f8b842..c4e49a8228683e 100644
--- a/libc/docs/stdbit.rst
+++ b/libc/docs/stdbit.rst
@@ -41,26 +41,26 @@ stdc_leading_ones_us |check|
stdc_leading_ones_ui |check|
stdc_leading_ones_ul |check|
stdc_leading_ones_ull |check|
-stdc_trailing_zeros_uc
-stdc_trailing_zeros_us
-stdc_trailing_zeros_ui
-stdc_trailing_zeros_ul
-stdc_trailing_zeros_ull
-stdc_trailing_ones_uc
-stdc_trailing_ones_us
-stdc_trailing_ones_ui
-stdc_trailing_ones_ul
-stdc_trailing_ones_ull
-stdc_first_leading_zero_uc
-stdc_first_leading_zero_us
-stdc_first_leading_zero_ui
-stdc_first_leading_zero_ul
-stdc_first_leading_zero_ull
-stdc_first_leading_one_uc
-stdc_first_leading_one_us
-stdc_first_leading_one_ui
-stdc_first_leading_one_ul
-stdc_first_leading_one_ull
+stdc_trailing_zeros_uc |check|
+stdc_trailing_zeros_us |check|
+stdc_trailing_zeros_ui |check|
+stdc_trailing_zeros_ul |check|
+stdc_trailing_zeros_ull |check|
+stdc_trailing_ones_uc |check|
+stdc_trailing_ones_us |check|
+stdc_trailing_ones_ui |check|
+stdc_trailing_ones_ul |check|
+stdc_trailing_ones_ull |check|
+stdc_first_leading_zero_uc |check|
+stdc_first_leading_zero_us |check|
+stdc_first_leading_zero_ui |check|
+stdc_first_leading_zero_ul |check|
+stdc_first_leading_zero_ull |check|
+stdc_first_leading_one_uc |check|
+stdc_first_leading_one_us |check|
+stdc_first_leading_one_ui |check|
+stdc_first_leading_one_ul |check|
+stdc_first_leading_one_ull |check|
stdc_first_trailing_zero_uc
stdc_first_trailing_zero_us
stdc_first_trailing_zero_ui
diff --git a/libc/include/llvm-libc-macros/stdbit-macros.h b/libc/include/llvm-libc-macros/stdbit-macros.h
index 693a45e63419ff..87c590e61e3999 100644
--- a/libc/include/llvm-libc-macros/stdbit-macros.h
+++ b/libc/include/llvm-libc-macros/stdbit-macros.h
@@ -86,6 +86,21 @@ inline unsigned stdc_first_leading_zero(unsigned long x) {
inline unsigned stdc_first_leading_zero(unsigned long long x) {
return stdc_first_leading_zero_ull(x);
}
+inline unsigned stdc_first_leading_one(unsigned char x) {
+ return stdc_first_leading_one_uc(x);
+}
+inline unsigned stdc_first_leading_one(unsigned short x) {
+ return stdc_first_leading_one_us(x);
+}
+inline unsigned stdc_first_leading_one(unsigned x) {
+ return stdc_first_leading_one_ui(x);
+}
+inline unsigned stdc_first_leading_one(unsigned long x) {
+ return stdc_first_leading_one_ul(x);
+}
+inline unsigned stdc_first_leading_one(unsigned long long x) {
+ return stdc_first_leading_one_ull(x);
+}
#else
#define stdc_leading_zeros(x) \
_Generic((x), \
@@ -122,6 +137,13 @@ inline unsigned stdc_first_leading_zero(unsigned long long x) {
unsigned: stdc_first_leading_zero_ui, \
unsigned long: stdc_first_leading_zero_ul, \
unsigned long long: stdc_first_leading_zero_ull)(x)
+#define stdc_first_leading_one(x) \
+ _Generic((x), \
+ unsigned char: stdc_first_leading_one_uc, \
+ unsigned short: stdc_first_leading_one_us, \
+ unsigned: stdc_first_leading_one_ui, \
+ unsigned long: stdc_first_leading_one_ul, \
+ unsigned long long: stdc_first_leading_one_ull)(x)
#endif // __cplusplus
#endif // __LLVM_LIBC_MACROS_STDBIT_MACROS_H
diff --git a/libc/spec/stdc.td b/libc/spec/stdc.td
index 1720a4a3c3aaf9..5e87831b907fb5 100644
--- a/libc/spec/stdc.td
+++ b/libc/spec/stdc.td
@@ -781,7 +781,8 @@ def StdC : StandardSpec<"stdc"> {
Macro<"stdc_leading_ones">,
Macro<"stdc_trailing_zeros">,
Macro<"stdc_trailing_ones">,
- Macro<"stdc_first_leading_zero">
+ Macro<"stdc_first_leading_zero">,
+ Macro<"stdc_first_leading_one">
], // Macros
[], // Types
[], // Enumerations
@@ -810,7 +811,12 @@ def StdC : StandardSpec<"stdc"> {
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>]>
+ FunctionSpec<"stdc_first_leading_zero_ull", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedLongLongType>]>,
+ FunctionSpec<"stdc_first_leading_one_uc", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedCharType>]>,
+ FunctionSpec<"stdc_first_leading_one_us", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedShortType>]>,
+ FunctionSpec<"stdc_first_leading_one_ui", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedIntType>]>,
+ FunctionSpec<"stdc_first_leading_one_ul", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedLongType>]>,
+ FunctionSpec<"stdc_first_leading_one_ull", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedLongLongType>]>
] // Functions
>;
diff --git a/libc/src/__support/CPP/bit.h b/libc/src/__support/CPP/bit.h
index 4115d67c7705c0..747b0ef371e405 100644
--- a/libc/src/__support/CPP/bit.h
+++ b/libc/src/__support/CPP/bit.h
@@ -231,6 +231,12 @@ template <typename T, typename = cpp::enable_if_t<cpp::is_unsigned_v<T>>>
return value == cpp::numeric_limits<T>::max() ? 0 : countl_one(value) + 1;
}
+template <typename T, typename = cpp::enable_if_t<cpp::is_unsigned_v<T>>>
+[[nodiscard]] LIBC_INLINE constexpr int first_leading_one(T value) {
+ return value == static_cast<T>(0) ? 0
+ : countl_zero<T>(static_cast<T>(value)) + 1;
+}
+
} // namespace LIBC_NAMESPACE::cpp
#endif // LLVM_LIBC_SRC___SUPPORT_CPP_BIT_H
diff --git a/libc/src/stdbit/CMakeLists.txt b/libc/src/stdbit/CMakeLists.txt
index 65d5f344307475..6ee93861b8db40 100644
--- a/libc/src/stdbit/CMakeLists.txt
+++ b/libc/src/stdbit/CMakeLists.txt
@@ -4,6 +4,7 @@ set(prefixes
trailing_zeros
trailing_ones
first_leading_zero
+ first_leading_one
)
set(suffixes c s i l ll)
foreach(prefix IN LISTS prefixes)
diff --git a/libc/src/stdbit/stdc_first_leading_one_uc.cpp b/libc/src/stdbit/stdc_first_leading_one_uc.cpp
new file mode 100644
index 00000000000000..02871595fdb6b8
--- /dev/null
+++ b/libc/src/stdbit/stdc_first_leading_one_uc.cpp
@@ -0,0 +1,20 @@
+//===-- Implementation of stdc_first_leading_one_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_one_uc.h"
+
+#include "src/__support/CPP/bit.h"
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(unsigned, stdc_first_leading_one_uc, (unsigned char value)) {
+ return static_cast<unsigned>(cpp::first_leading_one(value));
+}
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/stdbit/stdc_first_leading_one_uc.h b/libc/src/stdbit/stdc_first_leading_one_uc.h
new file mode 100644
index 00000000000000..58892c3f0ff298
--- /dev/null
+++ b/libc/src/stdbit/stdc_first_leading_one_uc.h
@@ -0,0 +1,18 @@
+//===-- Implementation header for stdc_first_leading_one_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_ONE_UC_H
+#define LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ONE_UC_H
+
+namespace LIBC_NAMESPACE {
+
+unsigned stdc_first_leading_one_uc(unsigned char value);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ONE_UC_H
diff --git a/libc/src/stdbit/stdc_first_leading_one_ui.cpp b/libc/src/stdbit/stdc_first_leading_one_ui.cpp
new file mode 100644
index 00000000000000..a6c7ef5a833914
--- /dev/null
+++ b/libc/src/stdbit/stdc_first_leading_one_ui.cpp
@@ -0,0 +1,20 @@
+//===-- Implementation of stdc_first_leading_one_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_one_ui.h"
+
+#include "src/__support/CPP/bit.h"
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(unsigned, stdc_first_leading_one_ui, (unsigned value)) {
+ return static_cast<unsigned>(cpp::first_leading_one(value));
+}
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/stdbit/stdc_first_leading_one_ui.h b/libc/src/stdbit/stdc_first_leading_one_ui.h
new file mode 100644
index 00000000000000..613adf4e1ff762
--- /dev/null
+++ b/libc/src/stdbit/stdc_first_leading_one_ui.h
@@ -0,0 +1,18 @@
+//===-- Implementation header for stdc_first_leading_one_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_ONE_UI_H
+#define LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ONE_UI_H
+
+namespace LIBC_NAMESPACE {
+
+unsigned stdc_first_leading_one_ui(unsigned value);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ONE_UI_H
diff --git a/libc/src/stdbit/stdc_first_leading_one_ul.cpp b/libc/src/stdbit/stdc_first_leading_one_ul.cpp
new file mode 100644
index 00000000000000..d1bcab5dda02a9
--- /dev/null
+++ b/libc/src/stdbit/stdc_first_leading_one_ul.cpp
@@ -0,0 +1,20 @@
+//===-- Implementation of stdc_first_leading_one_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_one_ul.h"
+
+#include "src/__support/CPP/bit.h"
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(unsigned, stdc_first_leading_one_ul, (unsigned long value)) {
+ return static_cast<unsigned>(cpp::first_leading_one(value));
+}
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/stdbit/stdc_first_leading_one_ul.h b/libc/src/stdbit/stdc_first_leading_one_ul.h
new file mode 100644
index 00000000000000..47c179f3fbacd1
--- /dev/null
+++ b/libc/src/stdbit/stdc_first_leading_one_ul.h
@@ -0,0 +1,18 @@
+//===-- Implementation header for stdc_first_leading_one_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_ONE_UL_H
+#define LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ONE_UL_H
+
+namespace LIBC_NAMESPACE {
+
+unsigned stdc_first_leading_one_ul(unsigned long value);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ONE_UL_H
diff --git a/libc/src/stdbit/stdc_first_leading_one_ull.cpp b/libc/src/stdbit/stdc_first_leading_one_ull.cpp
new file mode 100644
index 00000000000000..7be8f1051ec231
--- /dev/null
+++ b/libc/src/stdbit/stdc_first_leading_one_ull.cpp
@@ -0,0 +1,21 @@
+//===-- Implementation of stdc_first_leading_one_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_one_ull.h"
+
+#include "src/__support/CPP/bit.h"
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(unsigned, stdc_first_leading_one_ull,
+ (unsigned long long value)) {
+ return static_cast<unsigned>(cpp::first_leading_one(value));
+}
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/stdbit/stdc_first_leading_one_ull.h b/libc/src/stdbit/stdc_first_leading_one_ull.h
new file mode 100644
index 00000000000000..344d03f7100f47
--- /dev/null
+++ b/libc/src/stdbit/stdc_first_leading_one_ull.h
@@ -0,0 +1,18 @@
+//===-- Implementation header for stdc_first_leading_one_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_ONE_ULL_H
+#define LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ONE_ULL_H
+
+namespace LIBC_NAMESPACE {
+
+unsigned stdc_first_leading_one_ull(unsigned long long value);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ONE_ULL_H
diff --git a/libc/src/stdbit/stdc_first_leading_one_us.cpp b/libc/src/stdbit/stdc_first_leading_one_us.cpp
new file mode 100644
index 00000000000000..7a4c7e673f367f
--- /dev/null
+++ b/libc/src/stdbit/stdc_first_leading_one_us.cpp
@@ -0,0 +1,21 @@
+//===-- Implementation of stdc_first_leading_one_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_one_us.h"
+
+#include "src/__support/CPP/bit.h"
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(unsigned, stdc_first_leading_one_us,
+ (unsigned short value)) {
+ return static_cast<unsigned>(cpp::first_leading_one(value));
+}
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/stdbit/stdc_first_leading_one_us.h b/libc/src/stdbit/stdc_first_leading_one_us.h
new file mode 100644
index 00000000000000..9d5feaf1e92f08
--- /dev/null
+++ b/libc/src/stdbit/stdc_first_leading_one_us.h
@@ -0,0 +1,18 @@
+//===-- Implementation header for stdc_first_leading_one_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_ONE_US_H
+#define LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ONE_US_H
+
+namespace LIBC_NAMESPACE {
+
+unsigned stdc_first_leading_one_us(unsigned short value);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ONE_US_H
diff --git a/libc/test/include/stdbit_test.cpp b/libc/test/include/stdbit_test.cpp
index 9a66a76de20bc5..c2fbcb8ce2d321 100644
--- a/libc/test/include/stdbit_test.cpp
+++ b/libc/test/include/stdbit_test.cpp
@@ -50,6 +50,13 @@ unsigned stdc_first_leading_zero_ul(unsigned long) noexcept { return 0xEDU; }
unsigned stdc_first_leading_zero_ull(unsigned long long) noexcept {
return 0xEFU;
}
+unsigned stdc_first_leading_one_uc(unsigned char) noexcept { return 0xFAU; }
+unsigned stdc_first_leading_one_us(unsigned short) noexcept { return 0xFBU; }
+unsigned stdc_first_leading_one_ui(unsigned) noexcept { return 0xFCU; }
+unsigned stdc_first_leading_one_ul(unsigned long) noexcept { return 0xFDU; }
+unsigned stdc_first_leading_one_ull(unsigned long long) noexcept {
+ return 0xFFU;
+}
}
#include "include/llvm-libc-macros/stdbit-macros.h"
@@ -93,3 +100,11 @@ TEST(LlvmLibcStdbitTest, TypeGenericMacroFirstLeadingZero) {
EXPECT_EQ(stdc_first_leading_zero(0UL), 0xEDU);
EXPECT_EQ(stdc_first_leading_zero(0ULL), 0xEFU);
}
+
+TEST(LlvmLibcStdbitTest, TypeGenericMacroFirstLeadingOne) {
+ EXPECT_EQ(stdc_first_leading_one(static_cast<unsigned char>(0U)), 0xFAU);
+ EXPECT_EQ(stdc_first_leading_one(static_cast<unsigned short>(0U)), 0xFBU);
+ EXPECT_EQ(stdc_first_leading_one(0U), 0xFCU);
+ EXPECT_EQ(stdc_first_leading_one(0UL), 0xFDU);
+ EXPECT_EQ(stdc_first_leading_one(0ULL), 0xFFU);
+}
diff --git a/libc/test/src/__support/CPP/bit_test.cpp b/libc/test/src/__support/CPP/bit_test.cpp
index 00d8ca5d293ace..a70726d4feb241 100644
--- a/libc/test/src/__support/CPP/bit_test.cpp
+++ b/libc/test/src/__support/CPP/bit_test.cpp
@@ -213,4 +213,11 @@ TYPED_TEST(LlvmLibcBitTest, FirstLeadingZero, UnsignedTypes) {
cpp::numeric_limits<T>::digits - i);
}
+TYPED_TEST(LlvmLibcBitTest, FirstLeadingOne, UnsignedTypes) {
+ EXPECT_EQ(first_leading_one<T>(static_cast<T>(0)), 0);
+ for (int i = 0U; i != cpp::numeric_limits<T>::digits; ++i)
+ EXPECT_EQ(first_leading_one<T>(T(1) << i),
+ cpp::numeric_limits<T>::digits - i);
+}
+
} // namespace LIBC_NAMESPACE::cpp
diff --git a/libc/test/src/stdbit/CMakeLists.txt b/libc/test/src/stdbit/CMakeLists.txt
index bc7e49d186a0d5..e32663f88e8620 100644
--- a/libc/test/src/stdbit/CMakeLists.txt
+++ b/libc/test/src/stdbit/CMakeLists.txt
@@ -6,6 +6,7 @@ set(prefixes
trailing_zeros
trailing_ones
first_leading_zero
+ first_leading_one
)
set(suffixes c s i l ll)
foreach(prefix IN LISTS prefixes)
diff --git a/libc/test/src/stdbit/stdc_first_leading_one_uc_test.cpp b/libc/test/src/stdbit/stdc_first_leading_one_uc_test.cpp
new file mode 100644
index 00000000000000..b8c8db587098e4
--- /dev/null
+++ b/libc/test/src/stdbit/stdc_first_leading_one_uc_test.cpp
@@ -0,0 +1,21 @@
+//===-- Unittests for stdc_first_leading_one_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_one_uc.h"
+#include "test/UnitTest/Test.h"
+
+TEST(LlvmLibcStdcFirstLeadingOneUcTest, Zero) {
+ EXPECT_EQ(LIBC_NAMESPACE::stdc_first_leading_one_uc(0U), 0U);
+}
+
+TEST(LlvmLibcStdcFirstLeadingOneUcTest, OneHot) {
+ for (unsigned i = 0U; i != UCHAR_WIDTH; ++i)
+ EXPECT_EQ(LIBC_NAMESPACE::stdc_first_leading_one_uc(1U << i),
+ UCHAR_WIDTH - i);
+}
diff --git a/libc/test/src/stdbit/stdc_first_leading_one_ui_test.cpp b/libc/test/src/stdbit/stdc_first_leading_one_ui_test.cpp
new file mode 100644
index 00000000000000..319d7482c50f9e
--- /dev/null
+++ b/libc/test/src/stdbit/stdc_first_leading_one_ui_test.cpp
@@ -0,0 +1,21 @@
+//===-- Unittests for stdc_first_leading_one_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_one_ui.h"
+#include "test/UnitTest/Test.h"
+
+TEST(LlvmLibcStdcFirstLeadingOneUiTest, Zero) {
+ EXPECT_EQ(LIBC_NAMESPACE::stdc_first_leading_one_ui(0U), 0U);
+}
+
+TEST(LlvmLibcStdcFirstLeadingOneUiTest, OneHot) {
+ for (unsigned i = 0U; i != UINT_WIDTH; ++i)
+ EXPECT_EQ(LIBC_NAMESPACE::stdc_first_leading_one_ui(1U << i),
+ UINT_WIDTH - i);
+}
diff --git a/libc/test/src/stdbit/stdc_first_leading_one_ul_test.cpp b/libc/test/src/stdbit/stdc_first_leading_one_ul_test.cpp
new file mode 100644
index 00000000000000..5884cec418ce2b
--- /dev/null
+++ b/libc/test/src/stdbit/stdc_first_leading_one_ul_test.cpp
@@ -0,0 +1,21 @@
+//===-- Unittests for stdc_first_leading_one_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_one_ul.h"
+#include "test/UnitTest/Test.h"
+
+TEST(LlvmLibcStdcFirstLeadingOneUlTest, Zero) {
+ EXPECT_EQ(LIBC_NAMESPACE::stdc_first_leading_one_ul(0UL), 0U);
+}
+
+TEST(LlvmLibcStdcFirstLeadingOneUlTest, OneHot) {
+ for (unsigned i = 0U; i != ULONG_WIDTH; ++i)
+ EXPECT_EQ(LIBC_NAMESPACE::stdc_first_leading_one_ul(1UL << i),
+ ULONG_WIDTH - i);
+}
diff --git a/libc/test/src/stdbit/stdc_first_leading_one_ull_test.cpp b/libc/test/src/stdbit/stdc_first_leading_one_ull_test.cpp
new file mode 100644
index 00000000000000..bf57f16c1dcaaa
--- /dev/null
+++ b/libc/test/src/stdbit/stdc_first_leading_one_ull_test.cpp
@@ -0,0 +1,21 @@
+//===-- Unittests for stdc_first_leading_one_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_one_ull.h"
+#include "test/UnitTest/Test.h"
+
+TEST(LlvmLibcStdcFirstLeadingOneUllTest, Zero) {
+ EXPECT_EQ(LIBC_NAMESPACE::stdc_first_leading_one_ull(0ULL), 0U);
+}
+
+TEST(LlvmLibcStdcFirstLeadingOneUllTest, OneHot) {
+ for (unsigned i = 0U; i != ULLONG_WIDTH; ++i)
+ EXPECT_EQ(LIBC_NAMESPACE::stdc_first_leading_one_ull(1ULL << i),
+ ULLONG_WIDTH - i);
+}
diff --git a/libc/test/src/stdbit/stdc_first_leading_one_us_test.cpp b/libc/test/src/stdbit/stdc_first_leading_one_us_test.cpp
new file mode 100644
index 00000000000000..e9488335d9b008
--- /dev/null
+++ b/libc/test/src/stdbit/stdc_first_leading_one_us_test.cpp
@@ -0,0 +1,21 @@
+//===-- Unittests for stdc_first_leading_one_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_one_us.h"
+#include "test/UnitTest/Test.h"
+
+TEST(LlvmLibcStdcFirstLeadingOneUsTest, Zero) {
+ EXPECT_EQ(LIBC_NAMESPACE::stdc_first_leading_one_us(0U), 0U);
+}
+
+TEST(LlvmLibcStdcFirstLeadingOneUsTest, OneHot) {
+ for (unsigned i = 0U; i != USHRT_WIDTH; ++i)
+ EXPECT_EQ(LIBC_NAMESPACE::stdc_first_leading_one_us(1U << i),
+ USHRT_WIDTH - i);
+}
>From c2381aad04284a644370008cdee14fbb6e505767 Mon Sep 17 00:00:00 2001
From: Nick Desaulniers <ndesaulniers at google.com>
Date: Mon, 12 Feb 2024 10:23:05 -0800
Subject: [PATCH 2/4] add tg macros to doc
---
libc/docs/stdbit.rst | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/libc/docs/stdbit.rst b/libc/docs/stdbit.rst
index c4e49a8228683e..5ff36dcb0f5929 100644
--- a/libc/docs/stdbit.rst
+++ b/libc/docs/stdbit.rst
@@ -116,10 +116,10 @@ __STDC_ENDIAN_BIG__
__STDC_ENDIAN_NATIVE__
stdc_leading_zeros |check|
stdc_leading_ones |check|
-stdc_trailing_zeros
-stdc_trailing_ones
-stdc_first_leading_zero
-stdc_first_leading_one
+stdc_trailing_zeros |check|
+stdc_trailing_ones |check|
+stdc_first_leading_zero |check|
+stdc_first_leading_one |check|
stdc_first_trailing_zero
stdc_first_trailing_one
stdc_count_zeros
>From 950f8f71531dba4bdb0e1d580d9b2f9592433eea Mon Sep 17 00:00:00 2001
From: Nick Desaulniers <ndesaulniers at google.com>
Date: Tue, 13 Feb 2024 14:12:20 -0800
Subject: [PATCH 3/4] shorten ternary
---
libc/src/__support/CPP/bit.h | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/libc/src/__support/CPP/bit.h b/libc/src/__support/CPP/bit.h
index 747b0ef371e405..82020d8c60161c 100644
--- a/libc/src/__support/CPP/bit.h
+++ b/libc/src/__support/CPP/bit.h
@@ -233,8 +233,7 @@ template <typename T, typename = cpp::enable_if_t<cpp::is_unsigned_v<T>>>
template <typename T, typename = cpp::enable_if_t<cpp::is_unsigned_v<T>>>
[[nodiscard]] LIBC_INLINE constexpr int first_leading_one(T value) {
- return value == static_cast<T>(0) ? 0
- : countl_zero<T>(static_cast<T>(value)) + 1;
+ return !value ? 0 : countl_zero<T>(static_cast<T>(value)) + 1;
}
} // namespace LIBC_NAMESPACE::cpp
>From acb2d5a140a23b21857290f03f183953ea77cae8 Mon Sep 17 00:00:00 2001
From: Nick Desaulniers <ndesaulniers at google.com>
Date: Wed, 14 Feb 2024 09:12:22 -0800
Subject: [PATCH 4/4] implement first_leading_one in terms of
first_leading_zero
---
libc/src/__support/CPP/bit.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/libc/src/__support/CPP/bit.h b/libc/src/__support/CPP/bit.h
index 82020d8c60161c..23e305ab86219e 100644
--- a/libc/src/__support/CPP/bit.h
+++ b/libc/src/__support/CPP/bit.h
@@ -233,7 +233,7 @@ template <typename T, typename = cpp::enable_if_t<cpp::is_unsigned_v<T>>>
template <typename T, typename = cpp::enable_if_t<cpp::is_unsigned_v<T>>>
[[nodiscard]] LIBC_INLINE constexpr int first_leading_one(T value) {
- return !value ? 0 : countl_zero<T>(static_cast<T>(value)) + 1;
+ return first_leading_zero(static_cast<T>(~value));
}
} // namespace LIBC_NAMESPACE::cpp
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