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Revert _BitScanForward64 support

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It shows almost no improvment and adds a good
bunch of complexity.

So remove for now. No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba
2009-05-25 07:28:55 +01:00
parent d63ff85a43
commit f1591447cf
2 changed files with 50 additions and 98 deletions
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24
src/bitcount.h
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@@ -66,7 +66,6 @@ inline bool cpu_has_popcnt() {
}
#define POPCNT_INTRINSIC(x) __popcnt64(x)
#define BITSCAN_INTRINSIC(idx, x) _BitScanForward64(idx, x)
#elif defined(__INTEL_COMPILER) && (defined(__x86_64) || defined(_M_X64)) // Intel compiler
@@ -80,14 +79,12 @@ inline bool cpu_has_popcnt() {
}
#define POPCNT_INTRINSIC(x) _mm_popcnt_u64(x)
#define BITSCAN_INTRINSIC(idx, x) _BitScanForward64(idx, x)
#else // Safe fallback for unsupported compilers
inline bool cpu_has_popcnt() { return false; }
#define POPCNT_INTRINSIC(x) count_1s(x)
#define BITSCAN_INTRINSIC(idx, x) count_1s(x) // dummy
#endif
@@ -168,27 +165,6 @@ inline int count_1s_max_15(Bitboard b) {
}
/// pop_1st_bit() finds and clears the least significant nonzero bit in a
/// nonzero bitboard. If template parameter is true an intrinsic is called,
/// otherwise we fallback on a software implementation.
template<bool UseIntrinsic>
inline Square pop_1st_bit(Bitboard *b) {
return pop_1st_bit(b);
}
template<>
inline Square pop_1st_bit<true>(Bitboard *b) {
unsigned long idx;
Bitboard bb = *b;
BITSCAN_INTRINSIC(&idx, bb);
*b &= (bb - 1);
return Square(idx);
}
// Global variable initialized at startup that is set to true if
// CPU on which application runs supports POPCNT intrinsic. Unless
// DISABLE_POPCNT_SUPPORT is defined.