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Date: Fri, 17 Feb 2017 11:32:00 -0000
From: Richard Biener <rguenther@suse.de>
To: gcc-patches@gcc.gnu.org
Subject: Re: [PATCH] Fix PR79547
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On Fri, 17 Feb 2017, Marc Glisse wrote:

> On Fri, 17 Feb 2017, Richard Biener wrote:
> 
> > On Thu, 16 Feb 2017, Richard Biener wrote:
> > 
> > > 
> > > I am testing the following patch for PR79547.  Those builtins do not
> > > return anything that can be used to re-construct the pointer(s) passed
> > > to them.
> > > 
> > > Queued for GCC 8.
> > 
> > Actually we need calluse constraints.  Thus adjusted as follows.
> > 
> > Richard.
> > 
> > 2017-02-17  Richard Biener  <rguenther@suse.de>
> > 
> > 	PR tree-optimization/79547
> > 	* tree-ssa-structalias.c (find_func_aliases_for_builtin_call):
> > 	Handle strlen, strcmp, strncmp, strcasecmp, strncasecmp, memcmp,
> > 	bcmp, strspn, strcspn, __builtin_object_size and __builtin_constant_p
> > 	without any constraints.
> 
> We have EAF_NOESCAPE that we are using for non-builtins, though it probably
> gets little use there. Would it make sense to use it here as well, or would
> that be pointless?

EAF_NOESCAPE doesn't capture what we want here -- for pure and const
functions arguments already don't escape in EAF_NOESCAPEs sense it's
just that EAF_NOESCAPE doesn't cover "escaping" through the return value.
We do not have sth like ERF_RETURNS_NO_ARG.

Generally all explicitely handled builtins do not need any further
fn-spec attributes added in builtins.def.

Richard.