[xdebug-general] Re: Details on issue #1229?

Hi Rainer!

On Mon, 14 Dec 2015, Rainer Jung wrote:

> I'm testing XDebug 2.4.0RC3 in combination with PHP 7.0.0 on Solaris
> 10 Sparc.
>
> I'm seeing crashes with slightly unclear reproducibility. I wonder
> whether they are related to your issue #1229 (crashes because of -O2
> for GCC 4.8). I'm using GCC 4.9.3 in combination with -O2.
>
> The issue says same code gets removed under -O2. What part of the code
> is it? I'd like to check, whether that's also happening for gcc 4.9.3.
> Could you please provide any details?

It was line 1004 in xdebug_var.c - the one just above this one:

> #2 0xfe9d555c in xdebug_var_export (struc=0xffbfe528, struc[@]entry=0xffbfe5ec,
> str=str[@]entry=0xffbfe59c, level=level[@]entry=1, debug_zval=debug_zval[@]entry=0,
> options=options[@]entry=0x2398c0) at /tmp/pear/temp/xdebug/xdebug_var.c:1005
> tmpz = 0x0
> myht = <optimized out>
> tmp_str = <optimized out>
> is_temp = 0
> num = <optimized out>
> key = <optimized out>
> val = <optimized out>
>
> The tmpz 0x0 looks fishy to me, also I don't see how it could crash in this
> line (but it could in the next effective line). See below.

So it looks GCC 4.9 is affected too, for some reason, the

         zval *tmpz = &((*struc)->value.ref->val);

Got removed while compiling... Removing -O2 fixed it, but I am wondering
whether I am not doing something really wrong and that the compiler is
right? If you could provide some insight, that'd be awesome.

cheers,
Derick

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