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Rewrite bit counting functions

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Get rid of macros and use templates instead,
this is safer and allows us fix the warning:

ISO C++ forbids braced-groups within expressions

That broke compilation with -pedantic flag under
gcc and POPCNT enabled.

No functional and no performance change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba
2010-10-04 11:45:04 +02:00
parent 3249777cdb
commit d4876dc963
8 changed files with 66 additions and 69 deletions
Download Patch File Download Diff File Expand all files Collapse all files

89
src/bitcount.h
View File

@@ -24,27 +24,23 @@
#include "types.h"
// Select type of intrinsic bit count instruction to use, see
// README.txt on how to pgo compile with POPCNT support.
#if !defined(USE_POPCNT)
#define POPCNT_INTRINSIC(x) 0
#elif defined(_MSC_VER)
#define POPCNT_INTRINSIC(x) (int)__popcnt64(x)
#elif defined(__GNUC__)
enum BitCountType {
CNT64,
CNT64_MAX15,
CNT32,
CNT32_MAX15,
CNT_POPCNT
};
#define POPCNT_INTRINSIC(x) ({ \
unsigned long __ret; \
__asm__("popcnt %1, %0" : "=r" (__ret) : "r" (x)); \
__ret; })
/// count_1s() counts the number of nonzero bits in a bitboard.
/// We have different optimized versions according if platform
/// is 32 or 64 bits, and to the maximum number of nonzero bits.
/// We also support hardware popcnt instruction. See Readme.txt
/// on how to pgo compile with popcnt support.
template<BitCountType> inline int count_1s(Bitboard);
#endif
/// Software implementation of bit count functions
#if defined(IS_64BIT)
inline int count_1s(Bitboard b) {
template<>
inline int count_1s<CNT64>(Bitboard b) {
b -= ((b>>1) & 0x5555555555555555ULL);
b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
b = ((b>>4) + b) & 0x0F0F0F0F0F0F0F0FULL;
@@ -52,16 +48,16 @@ inline int count_1s(Bitboard b) {
return int(b >> 56);
}
inline int count_1s_max_15(Bitboard b) {
template<>
inline int count_1s<CNT64_MAX15>(Bitboard b) {
b -= (b>>1) & 0x5555555555555555ULL;
b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
b *= 0x1111111111111111ULL;
return int(b >> 60);
}
#else // if !defined(IS_64BIT)
inline int count_1s(Bitboard b) {
template<>
inline int count_1s<CNT32>(Bitboard b) {
unsigned w = unsigned(b >> 32), v = unsigned(b);
v -= (v >> 1) & 0x55555555; // 0-2 in 2 bits
w -= (w >> 1) & 0x55555555;
@@ -73,7 +69,8 @@ inline int count_1s(Bitboard b) {
return int(v >> 24);
}
inline int count_1s_max_15(Bitboard b) {
template<>
inline int count_1s<CNT32_MAX15>(Bitboard b) {
unsigned w = unsigned(b >> 32), v = unsigned(b);
v -= (v >> 1) & 0x55555555; // 0-2 in 2 bits
w -= (w >> 1) & 0x55555555;
@@ -84,27 +81,21 @@ inline int count_1s_max_15(Bitboard b) {
return int(v >> 28);
}
#endif // BITCOUNT
/// count_1s() counts the number of nonzero bits in a bitboard.
/// If template parameter is true an intrinsic is called, otherwise
/// we fallback on a software implementation.
template<bool UseIntrinsic>
inline int count_1s(Bitboard b) {
return UseIntrinsic ? POPCNT_INTRINSIC(b) : count_1s(b);
}
template<bool UseIntrinsic>
inline int count_1s_max_15(Bitboard b) {
return UseIntrinsic ? POPCNT_INTRINSIC(b) : count_1s_max_15(b);
template<>
inline int count_1s<CNT_POPCNT>(Bitboard b) {
#if !defined(USE_POPCNT)
return int(b != 0); // Avoid 'b not used' warning
#elif defined(_MSC_VER)
return __popcnt64(b);
#elif defined(__GNUC__)
unsigned long ret;
__asm__("popcnt %1, %0" : "=r" (ret) : "r" (b));
return ret;
#endif
}
// Detect hardware POPCNT support
/// cpu_has_popcnt() detects support for popcnt instruction at runtime
inline bool cpu_has_popcnt() {
int CPUInfo[4] = {-1};
@@ -113,9 +104,9 @@ inline bool cpu_has_popcnt() {
}
// Global constant initialized at startup that is set to true if
// CPU on which application runs supports POPCNT intrinsic. Unless
// USE_POPCNT is not defined.
/// CpuHasPOPCNT is a global constant initialized at startup that
/// is set to true if CPU on which application runs supports popcnt
/// hardware instruction. Unless USE_POPCNT is not defined.
#if defined(USE_POPCNT)
const bool CpuHasPOPCNT = cpu_has_popcnt();
#else
@@ -123,12 +114,12 @@ const bool CpuHasPOPCNT = false;
#endif
// Global constant used to print info about the use of 64 optimized
// functions to verify that a 64 bit compile has been correctly built.
/// CpuIs64Bit is a global constant initialized at compile time that
/// is set to true if CPU on which application runs is a 64 bits.
#if defined(IS_64BIT)
const bool CpuHas64BitPath = true;
const bool CpuIs64Bit = true;
#else
const bool CpuHas64BitPath = false;
const bool CpuIs64Bit = false;
#endif
#endif // !defined(BITCOUNT_H_INCLUDED)