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tweaks to hashing

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Faster hasing of booleans, correct potential loss of distinction
for a compound structure that ends in a symbol or keyword, and
shortcuiting lookup in an empty immutable hash table.
This commit is contained in:
Matthew Flatt 2016-07-09 06:13:54 -06:00
parent 52bfb32cd3
commit 671adc0de2
1 changed files with 15 additions and 3 deletions
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18
racket/src/racket/src/hash.c
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@ -1368,9 +1368,14 @@ XFORM_NONGCING static uintptr_t fast_equal_hash_key(Scheme_Object *o, uintptr_t
top: top:
t = SCHEME_TYPE(o); t = SCHEME_TYPE(o);
k += t;
switch(t) { switch(t) {
case scheme_true_type:
return k + PTR_TO_LONG(o);
break;
case scheme_false_type:
return k + PTR_TO_LONG(o);
break;
case scheme_integer_type: case scheme_integer_type:
{ {
uintptr_t iv = to_unsigned_hash(SCHEME_INT_VAL(o)); uintptr_t iv = to_unsigned_hash(SCHEME_INT_VAL(o));
@ -1484,7 +1489,7 @@ XFORM_NONGCING static uintptr_t fast_equal_hash_key(Scheme_Object *o, uintptr_t
# else # else
case scheme_keyword_type: case scheme_keyword_type:
case scheme_symbol_type: case scheme_symbol_type:
return PTR_TO_LONG(o); return k + PTR_TO_LONG(o);
# endif # endif
default: default:
{ {
@ -1889,7 +1894,7 @@ intptr_t scheme_equal_hash_key(Scheme_Object *o)
uintptr_t k; uintptr_t k;
int done = 1; int done = 1;
k = fast_equal_hash_key(o, 0, &done); k = fast_equal_hash_key(o, SCHEME_TYPE(o), &done);
if (done) if (done)
return to_signed_hash(k); return to_signed_hash(k);
else else
@ -1917,6 +1922,10 @@ XFORM_NONGCING static uintptr_t fast_equal_hash_key2(Scheme_Object *o, int *_don
*_done = 1; *_done = 1;
switch(t) { switch(t) {
case scheme_true_type:
return 1;
case scheme_false_type:
return 2;
case scheme_integer_type: case scheme_integer_type:
return t - SCHEME_INT_VAL(o); return t - SCHEME_INT_VAL(o);
#ifdef MZ_USE_SINGLE_FLOATS #ifdef MZ_USE_SINGLE_FLOATS
@ -3202,6 +3211,9 @@ Scheme_Object *scheme_hash_tree_get_w_key_wraps(Scheme_Hash_Tree *tree, Scheme_O
int stype, pos; int stype, pos;
tree = resolve_placeholder(tree); tree = resolve_placeholder(tree);
if (!tree->count)
return NULL;
stype = SCHEME_TYPE(tree); stype = SCHEME_TYPE(tree);
if (stype == scheme_eq_hash_tree_type) if (stype == scheme_eq_hash_tree_type)