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Unify BitCountType selection

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Now that HasPopCnt is a compile time constant we can
centralize and unify the BitCountType selection.

Also rename count_1s() in the more standard popcount()

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba
2011-12-31 09:46:43 +01:00
parent fb4b4f772e
commit e9296d694c
6 changed files with 50 additions and 44 deletions
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48
src/bitcount.h
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@@ -21,25 +21,29 @@
#if !defined(BITCOUNT_H_INCLUDED)
#define BITCOUNT_H_INCLUDED
#include <cassert>
#include "types.h"
enum BitCountType {
CNT64,
CNT64_MAX15,
CNT32,
CNT32_MAX15,
CNT_POPCNT
CNT_64,
CNT_64_MAX15,
CNT_32,
CNT_32_MAX15,
CNT_HW_POPCNT
};
/// 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);
/// Determine at compile time the best popcount<> specialization according if
/// platform is 32 or 64 bits, to the maximum number of nonzero bits to count or
/// use hardware popcnt instruction when available.
const BitCountType Full = HasPopCnt ? CNT_HW_POPCNT : Is64Bit ? CNT_64 : CNT_32;
const BitCountType Max15 = HasPopCnt ? CNT_HW_POPCNT : Is64Bit ? CNT_64_MAX15 : CNT_32_MAX15;
/// popcount() counts the number of nonzero bits in a bitboard
template<BitCountType> inline int popcount(Bitboard);
template<>
inline int count_1s<CNT64>(Bitboard b) {
inline int popcount<CNT_64>(Bitboard b) {
b -= ((b>>1) & 0x5555555555555555ULL);
b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
b = ((b>>4) + b) & 0x0F0F0F0F0F0F0F0FULL;
@@ -48,7 +52,7 @@ inline int count_1s<CNT64>(Bitboard b) {
}
template<>
inline int count_1s<CNT64_MAX15>(Bitboard b) {
inline int popcount<CNT_64_MAX15>(Bitboard b) {
b -= (b>>1) & 0x5555555555555555ULL;
b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
b *= 0x1111111111111111ULL;
@@ -56,7 +60,7 @@ inline int count_1s<CNT64_MAX15>(Bitboard b) {
}
template<>
inline int count_1s<CNT32>(Bitboard b) {
inline int popcount<CNT_32>(Bitboard b) {
unsigned w = unsigned(b >> 32), v = unsigned(b);
v -= (v >> 1) & 0x55555555; // 0-2 in 2 bits
w -= (w >> 1) & 0x55555555;
@@ -69,7 +73,7 @@ inline int count_1s<CNT32>(Bitboard b) {
}
template<>
inline int count_1s<CNT32_MAX15>(Bitboard b) {
inline int popcount<CNT_32_MAX15>(Bitboard b) {
unsigned w = unsigned(b >> 32), v = unsigned(b);
v -= (v >> 1) & 0x55555555; // 0-2 in 2 bits
w -= (w >> 1) & 0x55555555;
@@ -81,17 +85,27 @@ inline int count_1s<CNT32_MAX15>(Bitboard b) {
}
template<>
inline int count_1s<CNT_POPCNT>(Bitboard b) {
inline int popcount<CNT_HW_POPCNT>(Bitboard b) {
#if !defined(USE_POPCNT)
assert(false);
return int(b != 0); // Avoid 'b not used' warning
#elif defined(_MSC_VER) && defined(__INTEL_COMPILER)
return _mm_popcnt_u64(b);
#elif defined(_MSC_VER)
return (int)__popcnt64(b);
#elif defined(__GNUC__)
#else
unsigned long ret;
__asm__("popcnt %1, %0" : "=r" (ret) : "r" (b));
return ret;
#endif
}