Use intrinsic in pop_1st_bit() under MSVC 64 bits
Around 1% speedup when compiled with MSVC 64 No functional change. Signed-off-by: Marco Costalba <mcostalba@gmail.com>sf_2.3.1_base
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635be39acf
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5ea08e79c4
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@ -257,15 +257,25 @@ inline bool squares_aligned(Square s1, Square s2, Square s3) {
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/// pop_1st_bit() finds and clears the least significant nonzero bit in a
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/// nonzero bitboard.
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#if defined(USE_BSFQ) // Assembly code by Heinz van Saanen
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#if defined(USE_BSFQ)
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inline Square first_1(Bitboard b) {
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#if defined(_MSC_VER) && !defined(__INTEL_COMPILER)
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FORCE_INLINE Square first_1(Bitboard b) {
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unsigned long index;
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_BitScanForward64(&index, b);
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return (Square) index;
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}
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#else
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FORCE_INLINE Square first_1(Bitboard b) { // Assembly code by Heinz van Saanen
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Bitboard dummy;
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__asm__("bsfq %1, %0": "=r"(dummy): "rm"(b) );
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return (Square)(dummy);
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return (Square) dummy;
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}
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#endif
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inline Square pop_1st_bit(Bitboard* b) {
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FORCE_INLINE Square pop_1st_bit(Bitboard* b) {
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const Square s = first_1(*b);
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*b &= ~(1ULL<<s);
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return s;
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@ -77,9 +77,8 @@ typedef unsigned __int64 uint64_t;
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#define IS_64BIT
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#endif
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// Automatic detection for use of bsfq asm-instruction under Windows.
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// Works only in 64-bit mode. Does not work with MSVC.
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#if defined(_WIN64) && defined(__INTEL_COMPILER)
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// Automatic detection for use of bsfq asm-instruction under Windows
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#if defined(_WIN64)
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#define USE_BSFQ
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#endif
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