[swift-dev] JIT-ting Swift

[Robert Widmann]

%Sp is not an argument, it is the space necessary to hold a reference to the CommandLine enumeration's static argv member.  

When JIT'ing Swift, the value of argv doesn't matter because we replace the process' arguments dynamically https://github.com/apple/swift/blob/master/lib/Immediate/Immediate.cpp#L318.  Do you have a trace for the crash?

~Robert Widmann

2017/03/06 12:33、Alex Denisov via swift-dev <swift-dev at swift.org> のメッセージ:

> Hi there,
> 
> I could not find a list for swift-corelibs-xctest so I am posting it here.
> 
> I am trying to run tests based on XCTest (https://github.com/apple/swift-corelibs-xctest) using LLVM's JIT.
> Everything is working good so far. However, I am getting a crash.
> Based on a shallow investigation I can see that this is somehow related to the way Swift treats the command line arguments. Or, to be more precise, to the way I pass the arguments to the swift's 'main' function.
> 
> What I did so far is not different from what I do to run C or C++ using JIT:
> 
> auto main = ((int (*)(int, const char **))(intptr_t)mainPointer);
> const int argc = 1;
> const char *argv[] = { "some-name", NULL };
> auto result = main(argc, argv);
> 
> Based on what I see in the IR[1] the 'argv' has type "%Sp = type <{ i8* }>", which seems to be a struct with a pointer to something.
> 
> So the question is: what is being passed as a second argument to the 'main' function of a swift program?
> 
> Any other advice on JIT-ting Swift are more than welcome :)
> 
> [1] https://gist.github.com/AlexDenisov/3c10540b544e82cfb6e58e1452491904
> -- 
> AlexDenisov
> Software Engineer, https://lowlevelbits.org
> 
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