Recommit r339943 - Establish the <bit> header. NFC yet. Reviewed as https://reviews.llvm.org/D50815 - with a fix for the sanitizer bots
llvm-svn: 340045
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: e02ee4f013632aac34e1fb84d868984a91773e2a
diff --git a/include/bit b/include/bit
new file mode 100644
index 0000000..2d403bf
--- /dev/null
+++ b/include/bit
@@ -0,0 +1,169 @@
+// -*- C++ -*-
+//===------------------------------ bit ----------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===---------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_BIT
+#define _LIBCPP_BIT
+
+/*
+ bit synopsis
+
+namespace std {
+
+} // namespace std
+
+*/
+
+#include <__config>
+
+#if defined(__IBMCPP__)
+#include "support/ibm/support.h"
+#endif
+#if defined(_LIBCPP_COMPILER_MSVC)
+#include <intrin.h>
+#endif
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// Precondition: __x != 0
+inline _LIBCPP_INLINE_VISIBILITY
+unsigned __ctz(unsigned __x) {
+#ifndef _LIBCPP_COMPILER_MSVC
+ return static_cast<unsigned>(__builtin_ctz(__x));
+#else
+ static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
+ static_assert(sizeof(unsigned long) == 4, "");
+ unsigned long where;
+ // Search from LSB to MSB for first set bit.
+ // Returns zero if no set bit is found.
+ if (_BitScanForward(&where, __x))
+ return where;
+ return 32;
+#endif
+}
+
+inline _LIBCPP_INLINE_VISIBILITY
+unsigned long __ctz(unsigned long __x) {
+#ifndef _LIBCPP_COMPILER_MSVC
+ return static_cast<unsigned long>(__builtin_ctzl(__x));
+#else
+ static_assert(sizeof(unsigned long) == sizeof(unsigned), "");
+ return __ctz(static_cast<unsigned>(__x));
+#endif
+}
+
+inline _LIBCPP_INLINE_VISIBILITY
+unsigned long long __ctz(unsigned long long __x) {
+#ifndef _LIBCPP_COMPILER_MSVC
+ return static_cast<unsigned long long>(__builtin_ctzll(__x));
+#else
+ unsigned long where;
+// Search from LSB to MSB for first set bit.
+// Returns zero if no set bit is found.
+#if defined(_LIBCPP_HAS_BITSCAN64)
+ (defined(_M_AMD64) || defined(__x86_64__))
+ if (_BitScanForward64(&where, __x))
+ return static_cast<int>(where);
+#else
+ // Win32 doesn't have _BitScanForward64 so emulate it with two 32 bit calls.
+ // Scan the Low Word.
+ if (_BitScanForward(&where, static_cast<unsigned long>(__x)))
+ return where;
+ // Scan the High Word.
+ if (_BitScanForward(&where, static_cast<unsigned long>(__x >> 32)))
+ return where + 32; // Create a bit offset from the LSB.
+#endif
+ return 64;
+#endif // _LIBCPP_COMPILER_MSVC
+}
+
+// Precondition: __x != 0
+inline _LIBCPP_INLINE_VISIBILITY
+unsigned __clz(unsigned __x) {
+#ifndef _LIBCPP_COMPILER_MSVC
+ return static_cast<unsigned>(__builtin_clz(__x));
+#else
+ static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
+ static_assert(sizeof(unsigned long) == 4, "");
+ unsigned long where;
+ // Search from LSB to MSB for first set bit.
+ // Returns zero if no set bit is found.
+ if (_BitScanReverse(&where, __x))
+ return 31 - where;
+ return 32; // Undefined Behavior.
+#endif
+}
+
+inline _LIBCPP_INLINE_VISIBILITY
+unsigned long __clz(unsigned long __x) {
+#ifndef _LIBCPP_COMPILER_MSVC
+ return static_cast<unsigned long>(__builtin_clzl (__x));
+#else
+ static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
+ return __clz(static_cast<unsigned>(__x));
+#endif
+}
+
+inline _LIBCPP_INLINE_VISIBILITY
+unsigned long long __clz(unsigned long long __x) {
+#ifndef _LIBCPP_COMPILER_MSVC
+ return static_cast<unsigned long long>(__builtin_clzll(__x));
+#else
+ unsigned long where;
+// BitScanReverse scans from MSB to LSB for first set bit.
+// Returns 0 if no set bit is found.
+#if defined(_LIBCPP_HAS_BITSCAN64)
+ if (_BitScanReverse64(&where, __x))
+ return static_cast<int>(63 - where);
+#else
+ // Scan the high 32 bits.
+ if (_BitScanReverse(&where, static_cast<unsigned long>(__x >> 32)))
+ return 63 - (where + 32); // Create a bit offset from the MSB.
+ // Scan the low 32 bits.
+ if (_BitScanReverse(&where, static_cast<unsigned long>(__x)))
+ return 63 - where;
+#endif
+ return 64; // Undefined Behavior.
+#endif // _LIBCPP_COMPILER_MSVC
+}
+
+inline _LIBCPP_INLINE_VISIBILITY int __pop_count(unsigned __x) {
+#ifndef _LIBCPP_COMPILER_MSVC
+ return __builtin_popcount (__x);
+#else
+ static_assert(sizeof(unsigned) == 4, "");
+ return __popcnt(__x);
+#endif
+}
+
+inline _LIBCPP_INLINE_VISIBILITY int __pop_count(unsigned long __x) {
+#ifndef _LIBCPP_COMPILER_MSVC
+ return __builtin_popcountl (__x);
+#else
+ static_assert(sizeof(unsigned long) == 4, "");
+ return __popcnt(__x);
+#endif
+}
+
+inline _LIBCPP_INLINE_VISIBILITY int __pop_count(unsigned long long __x) {
+#ifndef _LIBCPP_COMPILER_MSVC
+ return __builtin_popcountll(__x);
+#else
+ static_assert(sizeof(unsigned long long) == 8, "");
+ return __popcnt64(__x);
+#endif
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_BIT