April 2012 - squirrelfish-dev - lists.macosforge.org

inlining scopechainnode into scope objects
by Andy Wingo 30 Apr '12

30 Apr '12

Hi Gavin, hi list, As we discussed last week, it could be a good idea to inline ScopeChainNode into scope objects, effectively giving scope objects a pointer to the next object in the chain. "With" objects would be on the chain via a wrapper object. This way we remove an indirection on accessing scopes and an allocation when creating them. I'm giving it a go, as it make some block stuff easier. So far so good. The current class hierarchy looks like: JSScopeObject: A new base class, holding the next pointer, global object, and global this + JSDynamicScope: A new class, wrapping "with" objects in the scope. + JSVariableObject + JSStaticScopeObject + JSActivation + JSGlobalObject Anyway, now my question: what is the deal with the "globalThis" object? Specifically, does it exist in a 1-to-1 relationship with the global object? If so, then it's fine to have globalThis be a (possibly settable) field of JSGlobalObject. If not, I have to rethink this plan. In the meantime I'll continue pushing forward here. Regards, & comments welcome, Andy -- Igalia, S.L.

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Instruction emission slow cases
by wingoog moon 17 Apr '12

17 Apr '12

Hi! As I understand there are two passes to translate SFX bytecode to the native code(functions privateCompileMainPass() and privateCompileSlowCases()). So whats the purpose of privateCompileSlowCases(). Why we need slow cases for each bytecodeInstruction? Is it needed when arguments of instruction not integer or something else? Thanks for attention!

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cti functions and emit_op_new_array
by wingoog moon 03 Apr '12

03 Apr '12

Hi!! Trying to understand cti functions on the example of emit_op_new_array functions. Here is the code of emit_op_new_array void JIT::emit_op_new_array(Instruction* currentInstruction) { JITStubCall stubCall(this, cti_op_new_array); stubCall.addArgument(Imm32(currentInstruction[2].u.operand)); stubCall.addArgument(Imm32(currentInstruction[3].u.operand)); stubCall.call(currentInstruction[1].u.operand); } As I understand stubCall.call(currentInstruction[1].u.operand) calls function DEFINE_STUB_FUNCTION(JSObject*, op_new_array) from JITStubs.cpp. And at this point execution of our JS programm is "interputing" and here C functions starting to work to "create array". The question is how can I get reference to the craeted array to manipulate it in future? And in general, can anyone please explain in detail how this scheme of cti functions works? Thanks!

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