Re: [PATCH] Fix middle-end/67133, part 1

[Jeff Law <law at redhat dot com>]

On 08/20/2015 10:51 AM, Marek Polacek wrote:
> > Based on the error, I suspect we've got a block ending with a GIMPLE_COND
> > with no successors in the CFG.
>
> Except that I'm also seeing a different error:
> /home/brq/mpolacek/gcc/libgo/go/text/template/exec.go:303:1: error: wrong
> outgoing edge flags at end of bb 6
> We have this bb:
>
> <bb 6>:
> # iftmp.1693_53 = PHI <0B(4)>
> _54 = t_5(D)->Pipe;
> GOTMP.163 = template.evalPipeline.pN19_text_template.state (s_7(D), dot, _31);
> [return slot optimization]
> dot = GOTMP.163;
> _61 = __go_new (&__go_tdn_text_template..text_template.state, 64);
> *_35 = *s_7(D);
> # DEBUG newState => _35
> _35->tmpl = iftmp.1693_55;
> GOTMP.166.value = dot;
> _66 = __go_new (&__go_td_AN22_text_template.variable1e, 40);
> SR.4170_67 = "$";
> SR.4171_68 = 1;
> MEM[(struct .text/template.variable *)&GOTMP.166] = "$";
> MEM[(struct .text/template.variable *)&GOTMP.166 + 8B] = 1;
> MEM[(struct .text/template.variable[1] *)_40][0] = GOTMP.166;
> _35->vars.__values = _40;
> _35->vars.__count = 1;
> _35->vars.__capacity = 1;
> _75 ={v} iftmp.1693_55->Tree;
> __builtin_trap ();
> _76 = _46->Root;
> D.8248.__methods =
> &__go_pimt__I25_.text_template_parse.treeFrpN24_text_template_parse.Treeee4_CopyFrN24_text_template_parse.Nodeee8_PositionFrN23_text_template_parse.Posee6_StringFrN6_stringee4_TypeFrN28_text_template_parse.NodeTypeeee__N28_text_template_parse.ListNode;
> D.8248.__object = _47;
> template.walk.pN19_text_template.state (_35, dot, D.8248);
> return;
>
> and single_succ_p (bb) is not satisfied, so it must have more outgoing edges.
> Not sure how can that happen...
OK, iftmp.1693_55 is NULL (via the PHI).  We inserted the trap.  That 
looks reasonable.

What does the CFG look like after splitting the block?   There should be 
flags you can pass to get the edges & flags as part of the debugging output.

My first guess would be some kind of exception handling edge, but I 
thought we avoided the transformation in that case.

Hmm, maybe seeing the CFG with edges & flags at the time of trap 
insertion would be useful too.


Jeff