On Nov 4, 2009, at 8:37 AM, ll Jefferry wrote:
Hi,
when i reading the jit for arm source code, i am not very clear the
functionality of the flowing functions:
ctiTrampoline
This code is used when entering from the C runtime into JIT generated
code. JIT generated code does not necessarily respect C calling
conventions, so this routine sets up the stack frame, preserves
registers, etc, as necessary to allow the JIT code to be run.
ctiVMThrowTrampoline
To perform certain operations the JIT will call back into C code.
Usually the C callback can just return in a perfectly normal fashion
and continue execution once it has completed, however in the case that
an exception is thrown special handling is required to change the
control flow. The return address of the C callback is instead changed
to point to this, and this piece of code handles looking up the
exception handler at which execution will be resumed.
ctiOpThrowNotCaught
This is used to from within cti_op_throw, which implements the 'throw'
keyword in JavaScript. The cti_op_throw method will attempt to look
up a handler routine that catches the exception. However if the
exception is not caught it is necessary to force an early termination
of JIT execution. The cti_op_throw C callback always modifies its
return address, either to point to the code for the appropriate
exception handler to catch the exception, or to ctiOpThrowNotCaught if
no handler is found.
could you explain to me?
and another question is that: in cacheFlush function, why the
system call number is 0xf0002? if it is defined by the toolchain?
Zoltan, Gabor?
thanks!
BR,
Jeff
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