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https://github.com/LuaJIT/LuaJIT.git
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Abstract out pointer hash to hashrot(). Tune hash constants.
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parent
6667ab0f26
commit
d05873ee0a
17
src/lj_asm.c
17
src/lj_asm.c
@ -1572,7 +1572,7 @@ static void asm_aref(ASMState *as, IRIns *ir)
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emit_rr(as, XO_MOV, dest, as->mrm.base);
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}
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/* Must match with hashkey() and hashrot() in lj_tab.c. */
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/* Must match with hash*() in lj_tab.c. */
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static uint32_t ir_khash(IRIns *ir)
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{
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uint32_t lo, hi;
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@ -1587,12 +1587,9 @@ static uint32_t ir_khash(IRIns *ir)
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} else {
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lua_assert(irt_isgcv(ir->t));
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lo = u32ptr(ir_kgc(ir));
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hi = lo - 0x04c11db7;
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hi = lo + HASH_BIAS;
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}
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lo ^= hi; hi = lj_rol(hi, 14);
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lo -= hi; hi = lj_rol(hi, 5);
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hi ^= lo; hi -= lj_rol(lo, 27);
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return hi;
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return hashrot(lo, hi);
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}
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/* Merge NE(HREF, niltv) check. */
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@ -1717,11 +1714,11 @@ static void asm_href(ASMState *as, IRIns *ir)
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} else { /* Must match with hashrot() in lj_tab.c. */
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emit_rmro(as, XO_ARITH(XOg_AND), dest, tab, offsetof(GCtab, hmask));
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emit_rr(as, XO_ARITH(XOg_SUB), dest, tmp);
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emit_shifti(as, XOg_ROL, tmp, 27);
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emit_shifti(as, XOg_ROL, tmp, HASH_ROT3);
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emit_rr(as, XO_ARITH(XOg_XOR), dest, tmp);
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emit_shifti(as, XOg_ROL, dest, 5);
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emit_shifti(as, XOg_ROL, dest, HASH_ROT2);
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emit_rr(as, XO_ARITH(XOg_SUB), tmp, dest);
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emit_shifti(as, XOg_ROL, dest, 14);
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emit_shifti(as, XOg_ROL, dest, HASH_ROT1);
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emit_rr(as, XO_ARITH(XOg_XOR), tmp, dest);
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if (irt_isnum(kt)) {
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emit_rr(as, XO_ARITH(XOg_ADD), dest, dest);
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@ -1735,7 +1732,7 @@ static void asm_href(ASMState *as, IRIns *ir)
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#endif
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} else {
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emit_rr(as, XO_MOV, tmp, key);
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emit_rmro(as, XO_LEA, dest, key, -0x04c11db7);
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emit_rmro(as, XO_LEA, dest, key, HASH_BIAS);
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}
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}
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}
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@ -1051,15 +1051,6 @@ static TRef rec_idx(jit_State *J, RecordIndex *ix)
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/* -- Upvalue access ------------------------------------------------------ */
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/* Shrink disambiguation hash into an 8 bit value. */
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static uint32_t shrink_dhash(uint32_t lo, uint32_t hi)
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{
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lo ^= hi; hi = lj_rol(hi, 14);
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lo -= hi; hi = lj_rol(hi, 5);
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hi ^= lo; hi -= lj_rol(lo, 27);
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return (hi & 0xff);
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}
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/* Record upvalue load/store. */
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static TRef rec_upvalue(jit_State *J, uint32_t uv, TRef val)
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{
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@ -1068,7 +1059,7 @@ static TRef rec_upvalue(jit_State *J, uint32_t uv, TRef val)
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IRRef uref;
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int needbarrier = 0;
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/* Note: this effectively limits LJ_MAX_UPVAL to 127. */
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uv = (uv << 8) | shrink_dhash(uvp->dhash, uvp->dhash-0x04c11db7);
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uv = (uv << 8) | (hashrot(uvp->dhash, uvp->dhash + HASH_BIAS) & 0xff);
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if (!uvp->closed) {
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/* In current stack? */
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if (uvval(uvp) >= J->L->stack && uvval(uvp) < J->L->maxstack) {
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21
src/lj_tab.c
21
src/lj_tab.c
@ -17,22 +17,19 @@
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/* -- Object hashing ------------------------------------------------------ */
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/* Hash values are masked with the table hash mask and used as an index. */
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#define hashmask(t, x) (&noderef(t->node)[(x) & t->hmask])
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static LJ_AINLINE Node *hashmask(const GCtab *t, uint32_t hash)
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{
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Node *n = noderef(t->node);
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return &n[hash & t->hmask];
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}
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/* String hashes are precomputed when they are interned. */
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#define hashstr(t, s) hashmask(t, (s)->hash)
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#define hashnum(t, o) hashrot(t, (o)->u32.lo, ((o)->u32.hi << 1))
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#define hashgcref(t, r) hashrot(t, gcrefu(r), gcrefu(r)-0x04c11db7)
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/* Scramble the bits of numbers and pointers. */
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static LJ_AINLINE Node *hashrot(const GCtab *t, uint32_t lo, uint32_t hi)
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{
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lo ^= hi; hi = lj_rol(hi, 14);
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lo -= hi; hi = lj_rol(hi, 5);
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hi ^= lo; hi -= lj_rol(lo, 27);
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return hashmask(t, hi);
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}
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#define hashlohi(t, lo, hi) hashmask((t), hashrot((lo), (hi)))
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#define hashnum(t, o) hashlohi((t), (o)->u32.lo, ((o)->u32.hi << 1))
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#define hashptr(t, p) hashlohi((t), u32ptr(p), u32ptr(p) + HASH_BIAS)
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#define hashgcref(t, r) hashlohi((t), gcrefu(r), gcrefu(r) + HASH_BIAS)
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/* Hash an arbitrary key and return its anchor position in the hash table. */
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static Node *hashkey(const GCtab *t, cTValue *key)
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15
src/lj_tab.h
15
src/lj_tab.h
@ -8,6 +8,21 @@
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#include "lj_obj.h"
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/* Hash constants. Tuned using a brute force search. */
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#define HASH_BIAS (-0x04c11db7)
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#define HASH_ROT1 14
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#define HASH_ROT2 5
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#define HASH_ROT3 13
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/* Scramble the bits of numbers and pointers. */
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static LJ_AINLINE uint32_t hashrot(uint32_t lo, uint32_t hi)
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{
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lo ^= hi; hi = lj_rol(hi, HASH_ROT1);
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lo -= hi; hi = lj_rol(hi, HASH_ROT2);
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hi ^= lo; hi -= lj_rol(lo, HASH_ROT3);
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return hi;
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}
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#define hsize2hbits(s) ((s) ? ((s)==1 ? 1 : 1+lj_fls((uint32_t)((s)-1))) : 0)
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LJ_FUNCA GCtab *lj_tab_new(lua_State *L, uint32_t asize, uint32_t hbits);
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