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Re: throw c++ exceptions from signal handler and -fnon-call-exceptions


"Chen, Miaobo" <miaobo.chen@intel.com> writes:

> I saw an example in libjava/include/i386_signal.h, in macro
> MAKE_THROW_FRAME, upon trapping instructions we advance eip by 2 and
> throw C++ exceptions from signal handler. My question is:
> 
> Why we advance eip by a fixed value 2 here? Does this work for any
> trapping instructions for invalid memory access on ia32? I tested with:
> 
> __asm__ ("movl  $0x4,0xffffffe8(%eax)"); //suppose eax=0 for invalid
> memory access
> 
> which is a 7 bytes instruction but looks it does not work anymore,
> neither did when advancing eip by 2 or 7.

In current mainline, MAKE_THROW_FRAME in libjava/include/i386-signal.h
does nothing.  According to the ChangeLog, the patch was made for
    http://gcc.gnu.org/PR26208

Ian


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