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Better idea for avoiding level-1 property cache collisions.

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This commit is contained in:
Brendan Eich 2008-08-08 14:28:10 -07:00
parent 5513550625
commit e63c1bc88e
1 changed files with 7 additions and 7 deletions
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14
js/src/jsinterp.h
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@ -148,17 +148,17 @@ typedef struct JSInlineFrame {
#define PROPERTY_CACHE_SIZE JS_BIT(PROPERTY_CACHE_LOG2)
#define PROPERTY_CACHE_MASK JS_BITMASK(PROPERTY_CACHE_LOG2)
/*
* Add kshape rather than xor it to avoid collisions between nearby bytecode
* that are evolving an object by setting successive properties, incrementing
* the object's scope->shape on each set.
*/
#define PROPERTY_CACHE_HASH(pc,kshape) \
((((jsuword)(pc) >> PROPERTY_CACHE_LOG2) ^ (jsuword)(pc) ^ (kshape)) & \
(((((jsuword)(pc) >> PROPERTY_CACHE_LOG2) ^ (jsuword)(pc)) + (kshape)) & \
PROPERTY_CACHE_MASK)
/*
* We shift kshape left by 1 to let the low bit of the pc avoid collisions
* between nearby bytecode that are evolving an object by setting properties
* and incrementing the object's scope->shape on each set.
*/
#define PROPERTY_CACHE_HASH_PC(pc,kshape) \
PROPERTY_CACHE_HASH(pc, (kshape) << 1)
PROPERTY_CACHE_HASH(pc, kshape)
#define PROPERTY_CACHE_HASH_ATOM(atom,obj,pobj) \
PROPERTY_CACHE_HASH((jsuword)(atom) >> 2, OBJ_SCOPE(obj)->shape)