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Re: PATCH to fix -Wrestrict ICE (PR middle-end/83463)


On Mon, Dec 18, 2017 at 10:00:36AM -0700, Martin Sebor wrote:
> On 12/18/2017 08:10 AM, Marek Polacek wrote:
> > I'm not entirely up to speed with this code, but this one seemed sufficiently
> > obvious: check INTEGRAL_TYPE_P before looking at a tree's min/max value.
> > Otherwise, go with maxobjsize.
> > 
> > Bootstrapped/regtested on x86_64-linux, ok for trunk?
> 
> Thanks for the fix.  I noticed the problem only comes up when
> memcpy is declared without a prototype.  Otherwise, the memcpy
> call is eliminated early on (during gimplification?)  So while
> avoiding the ICE is obviously a necessary change, I wonder if
> this bug also suggests a missing optimization that might still
> be relevant (i.e., eliminating memcpy() with a zero size for
> a memcpy without a prototype):

No, we shouldn't try to optimize if people mess up stuff.
What happens in this case is that
gimple_builtin_call_types_compatible_p
will fail, thus gimple_call_builtin_p and we won't be treating it specially.

That just shows a problem in the new pass:
  tree func = gimple_call_fndecl (call);
  if (!func || DECL_BUILT_IN_CLASS (func) != BUILT_IN_NORMAL)
    return;
is just wrong, it should have been:
  if (!gimple_call_builtin_p (call, BUILT_IN_NORMAL))
    return;

Then you don't need to worry about float or _Complex int third argument,
or just 2 or 27 arguments instead of 3 for memcpy, etc.

	Jakub


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