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L1/L2 friendly PhaseTable[]

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In Movepicker c'tor we access during initialization one of
MainSearchPhaseIndex..QsearchWithoutChecksPhaseIndex globals.

Postpone definition of PhaseTable[] just after them so that
when PhaseTable[] will be accessed later in get_next_move()
it will be already present in L1/L2.

It works like an implicit prefetching of PhaseTable[].

Also shrink PhaseTable[] to fit an L1 cache line of 16 bytes
using uint8_t instead of int.

This apparentely innocuous patch gives an astonish speed
up of 1.6% under MSVC 2010 beta, pgo optimized !

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba
2009-08-15 15:18:17 +01:00
parent f3d0b76feb
commit e0c47a6ceb
2 changed files with 9 additions and 2 deletions
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4
src/movepick.cpp
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@@ -42,12 +42,12 @@ namespace {
/// Variables /// Variables
MovePicker::MovegenPhase PhaseTable[32]; CACHE_LINE_ALIGNMENT
int MainSearchPhaseIndex; int MainSearchPhaseIndex;
int EvasionsPhaseIndex; int EvasionsPhaseIndex;
int QsearchWithChecksPhaseIndex; int QsearchWithChecksPhaseIndex;
int QsearchWithoutChecksPhaseIndex; int QsearchWithoutChecksPhaseIndex;
uint8_t PhaseTable[32];
} }

7
src/types.h
View File

@@ -66,4 +66,11 @@ typedef uint64_t Bitboard;
#define USE_BSFQ #define USE_BSFQ
#endif #endif
// Cache line alignment specification
#if defined(_MSC_VER) || defined(__INTEL_COMPILER)
#define CACHE_LINE_ALIGNMENT __declspec(align(64))
#else
#define CACHE_LINE_ALIGNMENT __attribute__ ((aligned(64)))
#endif
#endif // !defined(TYPES_H_INCLUDED) #endif // !defined(TYPES_H_INCLUDED)