How to debug the SFX

http://mac-os-forge.2317878.n4.nabble.com/x86-64-JIT-td177690.html#a177705

Q: FWIW, it crashes with a corrupted stack: 

(gdb) bt 
#0  0x00007fd115002c00 in ?? () 
#1  0x00007fd11f4f6d26 in JSC::JITStubs::cti_op_call_NotJSFunction (args=0x7fff27e13820) at ../JavaScriptCore/runtime/JSCell.h:206 
#2  0x00007fd11fc55a3a in ?? () 
#3  0x0000000000000000 in ?? () 

A: I'd suggest trying to produce a reduction of the test case your   

looking at – JIT crashers can usually be reduced down to a very small   
test case.  You may then want to step though the JIT code to see where   
the bogus value is coming from.  Adding calls to breakpoint() from   
JIT::privateCompile and JIT::privateCompileMainPass can help with   
this, inserting breakpoints into the JIT code that the debugger will   

then hit.