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Abstract out pointer hash to hashrot(). Tune hash constants.

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This commit is contained in:
Mike Pall
2010-07-21 21:42:40 +02:00
parent 6667ab0f26
commit d05873ee0a
4 changed files with 32 additions and 32 deletions
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11
src/lj_record.c
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@@ -1051,15 +1051,6 @@ static TRef rec_idx(jit_State *J, RecordIndex *ix)
/* -- Upvalue access ------------------------------------------------------ */
/* Shrink disambiguation hash into an 8 bit value. */
static uint32_t shrink_dhash(uint32_t lo, uint32_t hi)
{
lo ^= hi; hi = lj_rol(hi, 14);
lo -= hi; hi = lj_rol(hi, 5);
hi ^= lo; hi -= lj_rol(lo, 27);
return (hi & 0xff);
}
/* Record upvalue load/store. */
static TRef rec_upvalue(jit_State *J, uint32_t uv, TRef val)
{
@@ -1068,7 +1059,7 @@ static TRef rec_upvalue(jit_State *J, uint32_t uv, TRef val)
IRRef uref;
int needbarrier = 0;
/* Note: this effectively limits LJ_MAX_UPVAL to 127. */
uv = (uv << 8) | shrink_dhash(uvp->dhash, uvp->dhash-0x04c11db7);
uv = (uv << 8) | (hashrot(uvp->dhash, uvp->dhash + HASH_BIAS) & 0xff);
if (!uvp->closed) {
/* In current stack? */
if (uvval(uvp) >= J->L->stack && uvval(uvp) < J->L->maxstack) {