From 6cc099bf98f384de1de3c0d8542c83db43fb5cec Mon Sep 17 00:00:00 2001 From: Sverker Eriksson Date: Tue, 10 Feb 2015 23:32:12 +0100 Subject: erts: Make hashmap compare non-recursive --- erts/emulator/beam/utils.c | 253 +++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 234 insertions(+), 19 deletions(-) (limited to 'erts/emulator/beam/utils.c') diff --git a/erts/emulator/beam/utils.c b/erts/emulator/beam/utils.c index 9fd53e941d..f79cb8db7d 100644 --- a/erts/emulator/beam/utils.c +++ b/erts/emulator/beam/utils.c @@ -2512,7 +2512,18 @@ Sint erts_cmp_rel_opt(Eterm a, Eterm* a_base, Eterm b, Eterm* b_base, int exact) Sint erts_cmp(Eterm a, Eterm b, int exact) #endif { - DECLARE_WSTACK(stack); +#define PSTACK_TYPE struct erts_cmp_hashmap_state + struct erts_cmp_hashmap_state { + Sint wstack_rollback; + int was_exact; + Eterm *ap; + Eterm *bp; + Eterm min_key; + Sint cmp_res; /* result so far -1,0,+1 */ + }; + PSTACK_DECLARE(hmap_stack, 1); + WSTACK_DECLARE(stack); + WSTACK_DECLARE(b_stack); /* only used by hashmaps */ Eterm* aa; Eterm* bb; int i; @@ -2528,6 +2539,26 @@ Sint erts_cmp(Eterm a, Eterm b, int exact) Uint32 *anum; Uint32 *bnum; +/* The WSTACK contains naked Eterms and Operations marked with header-tags */ +#define OP_BITS 4 +#define OP_MASK 0xF +#define TERM_ARRAY_OP 0 +#define SWITCH_EXACT_OFF_OP 1 +#define HASHMAP_PHASE1_ARE_KEYS_EQUAL 2 +#define HASHMAP_PHASE1_IS_MIN_KEY 3 +#define HASHMAP_PHASE1_CMP_VALUES 4 +#define HASHMAP_PHASE2_ARE_KEYS_EQUAL 5 +#define HASHMAP_PHASE2_IS_MIN_KEY_A 6 +#define HASHMAP_PHASE2_IS_MIN_KEY_B 7 + + +#define OP_WORD(OP) (((OP) << _TAG_PRIMARY_SIZE) | TAG_PRIMARY_HEADER) +#define TERM_ARRAY_OP_WORD(SZ) OP_WORD(((SZ) << OP_BITS) | TERM_ARRAY_OP) + +#define GET_OP(WORD) (ASSERT(is_header(WORD)), ((WORD) >> _TAG_PRIMARY_SIZE) & OP_MASK) +#define GET_OP_ARG(WORD) (ASSERT(is_header(WORD)), ((WORD) >> (OP_BITS + _TAG_PRIMARY_SIZE))) + + #define RETURN_NEQ(cmp) { j=(cmp); ASSERT(j != 0); goto not_equal; } #define ON_CMP_GOTO(cmp) if ((j=(cmp)) == 0) goto pop_next; else goto not_equal @@ -2543,6 +2574,8 @@ Sint erts_cmp(Eterm a, Eterm b, int exact) } while (0) +bodyrecur: + j = 0; tailrecur: if (is_same(a,a_base,b,b_base)) { /* Equal values or pointers. */ goto pop_next; @@ -2692,28 +2725,60 @@ tailrecur_ne: } else { /* Value array */ - WSTACK_PUSH3(stack, i, (UWord)(bb+1), (UWord)(aa+1) | TAG_PRIMARY_HEADER); - /* Marker to switch back from 'exact' compare */ - WSTACK_PUSH(stack, (UWord)NULL | TAG_PRIMARY_HEADER); + WSTACK_PUSH3(stack, (UWord)(bb+1), (UWord)(aa+1), TERM_ARRAY_OP_WORD(i)); + /* Switch back from 'exact' key compare */ + WSTACK_PUSH(stack, OP_WORD(SWITCH_EXACT_OFF_OP)); /* Now do 'exact' compare of key tuples */ a = *aa; b = *bb; exact = 1; - goto tailrecur; + goto bodyrecur; } case (_TAG_HEADER_HASHMAP >> _TAG_PRIMARY_SIZE) : { + struct erts_cmp_hashmap_state* sp; if (!is_hashmap_rel(b,b_base)) { a_tag = HASHMAP_DEF; goto mixed_types; } - i = (((hashmap_head_t*) hashmap_val_rel(a,a_base))->size - - ((hashmap_head_t*) hashmap_val_rel(b,b_base))->size); + i = hashmap_size_rel(a,a_base) - hashmap_size_rel(b,b_base); if (i) { RETURN_NEQ(i); } - ON_CMP_GOTO(hashmap_cmp(a, b)); + if (hashmap_size_rel(a,a_base) == 0) { + goto pop_next; + } + + /* Hashmap compare strategy: + Phase 1. While keys are identical + Do synchronous stepping through leafs of both trees in hash + order. Maintain value compare result of minimal key. + + Phase 2. If key diff was found in phase 1 + Ignore values from now on. + Continue iterate trees by always advancing the one + lagging behind hash-wise. Identical keys are skipped. + A minimal key can only be candidate as tie-breaker if we + have passed that hash value in the other tree (which means + the key did not exist in the other tree). + */ + + sp = PSTACK_PUSH(hmap_stack); + hashmap_iterator_init(&stack, a); + hashmap_iterator_init(&b_stack, b); + sp->ap = hashmap_iterator_next(&stack); + sp->bp = hashmap_iterator_next(&b_stack); + sp->cmp_res = 0; + ASSERT(sp->ap && sp->bp); + + a = CAR(sp->ap); + b = CAR(sp->bp); + sp->was_exact = exact; + exact = 1; + WSTACK_PUSH(stack, OP_WORD(HASHMAP_PHASE1_ARE_KEYS_EQUAL)); + sp->wstack_rollback = WSTACK_COUNT(stack); + goto bodyrecur; } case (_TAG_HEADER_FLOAT >> _TAG_PRIMARY_SIZE): if (!is_float_rel(b,b_base)) { @@ -3074,8 +3139,7 @@ term_array: /* arrays in 'aa' and 'bb', length in 'i' */ goto not_equal; } } else { - /* (ab)Use TAG_PRIMARY_HEADER to recognize a term_array */ - WSTACK_PUSH3(stack, i, (UWord)bb, (UWord)aa | TAG_PRIMARY_HEADER); + WSTACK_PUSH3(stack, (UWord)bb, (UWord)aa, TERM_ARRAY_OP_WORD(i)); goto tailrecur_ne; } } @@ -3087,28 +3151,179 @@ term_array: /* arrays in 'aa' and 'bb', length in 'i' */ pop_next: if (!WSTACK_ISEMPTY(stack)) { UWord something = WSTACK_POP(stack); - if (primary_tag((Eterm) something) == TAG_PRIMARY_HEADER) { /* a term_array */ - if (something == ((UWord)NULL | TAG_PRIMARY_HEADER)) { + struct erts_cmp_hashmap_state* sp; + if (primary_tag((Eterm) something) == TAG_PRIMARY_HEADER) { /* an operation */ + switch (GET_OP(something)) { + case TERM_ARRAY_OP: + i = GET_OP_ARG(something); + aa = (Eterm*)WSTACK_POP(stack); + bb = (Eterm*) WSTACK_POP(stack); + goto term_array; + + case SWITCH_EXACT_OFF_OP: /* Done with exact compare of map keys, switch back */ ASSERT(exact); exact = 0; goto pop_next; - } - aa = (Eterm *)something; - bb = (Eterm*) WSTACK_POP(stack); - i = WSTACK_POP(stack); - goto term_array; + + case HASHMAP_PHASE1_ARE_KEYS_EQUAL: { + sp = PSTACK_TOP(hmap_stack); + if (j) { + /* Key diff found, enter phase 2 */ + if (hashmap_key_hash_cmp(sp->ap, sp->bp) < 0) { + sp->min_key = CAR(sp->ap); + sp->cmp_res = -1; + sp->ap = hashmap_iterator_next(&stack); + } + else { + sp->min_key = CAR(sp->bp); + sp->cmp_res = 1; + sp->bp = hashmap_iterator_next(&b_stack); + } + exact = 1; /* only exact key compares in phase 2 */ + goto case_HASHMAP_PHASE2_LOOP; + } + + /* No key diff found so far, compare values if min key */ + + if (sp->cmp_res) { + a = CAR(sp->ap); + b = sp->min_key; + exact = 1; + WSTACK_PUSH(stack, OP_WORD(HASHMAP_PHASE1_IS_MIN_KEY)); + sp->wstack_rollback = WSTACK_COUNT(stack); + goto bodyrecur; + } + /* no min key-value found yet */ + a = CDR(sp->ap); + b = CDR(sp->bp); + exact = sp->was_exact; + WSTACK_PUSH(stack, OP_WORD(HASHMAP_PHASE1_CMP_VALUES)); + sp->wstack_rollback = WSTACK_COUNT(stack); + goto bodyrecur; + } + case HASHMAP_PHASE1_IS_MIN_KEY: + sp = PSTACK_TOP(hmap_stack); + if (j < 0) { + a = CDR(sp->ap); + b = CDR(sp->bp); + exact = sp->was_exact; + WSTACK_PUSH(stack, OP_WORD(HASHMAP_PHASE1_CMP_VALUES)); + sp->wstack_rollback = WSTACK_COUNT(stack); + goto bodyrecur; + } + goto case_HASHMAP_PHASE1_LOOP; + + case HASHMAP_PHASE1_CMP_VALUES: + sp = PSTACK_TOP(hmap_stack); + if (j) { + sp->cmp_res = j; + sp->min_key = CAR(sp->ap); + } + case_HASHMAP_PHASE1_LOOP: + sp->ap = hashmap_iterator_next(&stack); + sp->bp = hashmap_iterator_next(&b_stack); + if (!sp->ap) { + /* end of maps with identical keys */ + ASSERT(!sp->bp); + j = sp->cmp_res; + exact = sp->was_exact; + (void) PSTACK_POP(hmap_stack); + ON_CMP_GOTO(j); + } + a = CAR(sp->ap); + b = CAR(sp->bp); + exact = 1; + WSTACK_PUSH(stack, OP_WORD(HASHMAP_PHASE1_ARE_KEYS_EQUAL)); + sp->wstack_rollback = WSTACK_COUNT(stack); + goto bodyrecur; + + case_HASHMAP_PHASE2_LOOP: + if (sp->ap && sp->bp) { + a = CAR(sp->ap); + b = CAR(sp->bp); + ASSERT(exact); + WSTACK_PUSH(stack, OP_WORD(HASHMAP_PHASE2_ARE_KEYS_EQUAL)); + sp->wstack_rollback = WSTACK_COUNT(stack); + goto bodyrecur; + } + goto case_HASHMAP_PHASE2_NEXT_STEP; + + case HASHMAP_PHASE2_ARE_KEYS_EQUAL: + sp = PSTACK_TOP(hmap_stack); + if (j == 0) { + /* keys are equal, skip them */ + sp->ap = hashmap_iterator_next(&stack); + sp->bp = hashmap_iterator_next(&b_stack); + goto case_HASHMAP_PHASE2_LOOP; + } + /* fall through */ + case_HASHMAP_PHASE2_NEXT_STEP: + if (sp->ap || sp->bp) { + if (hashmap_key_hash_cmp(sp->ap, sp->bp) < 0) { + ASSERT(sp->ap); + a = CAR(sp->ap); + b = sp->min_key; + ASSERT(exact); + WSTACK_PUSH(stack, OP_WORD(HASHMAP_PHASE2_IS_MIN_KEY_A)); + } + else { /* hash_cmp > 0 */ + ASSERT(sp->bp); + a = CAR(sp->bp); + b = sp->min_key; + ASSERT(exact); + WSTACK_PUSH(stack, OP_WORD(HASHMAP_PHASE2_IS_MIN_KEY_B)); + } + sp->wstack_rollback = WSTACK_COUNT(stack); + goto bodyrecur; + } + /* End of both maps */ + j = sp->cmp_res; + exact = sp->was_exact; + (void) PSTACK_POP(hmap_stack); + ON_CMP_GOTO(j); + + case HASHMAP_PHASE2_IS_MIN_KEY_A: + sp = PSTACK_TOP(hmap_stack); + if (j < 0) { + sp->min_key = CAR(sp->ap); + sp->cmp_res = -1; + } + sp->ap = hashmap_iterator_next(&stack); + goto case_HASHMAP_PHASE2_LOOP; + + case HASHMAP_PHASE2_IS_MIN_KEY_B: + sp = PSTACK_TOP(hmap_stack); + if (j < 0) { + sp->min_key = CAR(sp->bp); + sp->cmp_res = 1; + } + sp->bp = hashmap_iterator_next(&b_stack); + goto case_HASHMAP_PHASE2_LOOP; + + default: + ASSERT(!"Invalid cmp op"); + } /* switch */ } a = (Eterm) something; b = (Eterm) WSTACK_POP(stack); goto tailrecur; } - DESTROY_WSTACK(stack); + ASSERT(PSTACK_IS_EMPTY(hmap_stack)); + PSTACK_DESTROY(hmap_stack); + WSTACK_DESTROY(stack); + WSTACK_DESTROY(b_stack); return 0; not_equal: - DESTROY_WSTACK(stack); + if (!PSTACK_IS_EMPTY(hmap_stack)) { + WSTACK_ROLLBACK(stack, PSTACK_TOP(hmap_stack)->wstack_rollback); + goto pop_next; + } + PSTACK_DESTROY(hmap_stack); + WSTACK_DESTROY(stack); + WSTACK_DESTROY(b_stack); return j; #undef CMP_NODES -- cgit v1.2.3