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ARM: Optimize hash algorithm for 3-operand CPUs.

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Mike Pall 2011-05-31 21:38:16 +02:00
parent 514ccfceb8
commit 496d3753f5
1 changed files with 8 additions and 0 deletions
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8
src/lj_tab.h
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@ -17,9 +17,17 @@
/* Scramble the bits of numbers and pointers. */ /* Scramble the bits of numbers and pointers. */
static LJ_AINLINE uint32_t hashrot(uint32_t lo, uint32_t hi) static LJ_AINLINE uint32_t hashrot(uint32_t lo, uint32_t hi)
{ {
#if LJ_TARGET_X86ORX64
/* Prefer variant that compiles well for a 2-operand CPU. */
lo ^= hi; hi = lj_rol(hi, HASH_ROT1); lo ^= hi; hi = lj_rol(hi, HASH_ROT1);
lo -= hi; hi = lj_rol(hi, HASH_ROT2); lo -= hi; hi = lj_rol(hi, HASH_ROT2);
hi ^= lo; hi -= lj_rol(lo, HASH_ROT3); hi ^= lo; hi -= lj_rol(lo, HASH_ROT3);
#else
lo ^= hi;
lo = lo - lj_rol(hi, HASH_ROT1);
hi = lo ^ lj_rol(hi, HASH_ROT1 + HASH_ROT2);
hi = hi - lj_rol(lo, HASH_ROT3);
#endif
return hi; return hi;
} }