June 2009 - squirrelfish-dev - lists.macosforge.org

http://trac.webkit.org/changeset/45039
by Geoffrey Garen 24 Jun '09

24 Jun '09

Traditionally, if we find a dictionary in the prototype chain when we're trying to cache, we do a fromDictionary transition, so the cache can succeed. For example, in tryCacheGetById: // Since we're accessing a prototype in a loop, it's a good bet that it // should not be treated as a dictionary. if (slotBaseObject->structure()->isDictionary()) slotBaseObject- >setStructure(Structure::fromDictionaryTransition(slotBaseObject- >structure())); Is there a good reason not to do that in this case? Geoff

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http://trac.webkit.org/changeset/44797
by Geoffrey Garen 18 Jun '09

18 Jun '09

> Roll out r43849 as it appears that we cannot rely on the address of > an objects property storage being constant even if the structure is > unchanged. Did you figure out why we can't rely on the address of an object's property storage being constant even if its structure is unchanged? It's fine to roll out the change to fix the crash for now, but I'd rather not lose this speedup. Do we need a bug for figuring out what's going on here and rolling back in the optimization? Geoff

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X86 instructions in JITArithmetic?
by Gabor Loki 04 Jun '09

04 Jun '09

Hi, I was wondering why JITArithmetic.cpp uses so many functions from X86Assembler. This should not be happened. MacroAssembler was introduced to be the 'common interface' for every back ends (not only for x86). Am I right? For example: In 'emit_op_rshift' function http://trac.webkit.org/browser/trunk/JavaScriptCore/jit/JITArithmetic.cpp#L… 121#if USE(ALTERNATE_JSIMMEDIATE) 122 addSlowCase(emitJumpIfNotImmediateNumber(regT0)); 123 __ movq_rr(regT0, X86::xmm0); 124#else 125 emitJumpSlowCaseIfNotJSCell(regT0, op1); 126 addSlowCase(checkStructure(regT0, m_globalData->numberStructure.get())); ******************* 127 __ movsd_mr(FIELD_OFFSET(JSNumberCell, m_value), regT0, X86::xmm0); ******************* 128#endif IMHO, if a platform specific solution have to be used, creates a separate file which will contain those solutions/optimizations. What do you think about this issue? --Gabor

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