Re: Stuff to include in libgccjit 5.2

[David Malcolm <dmalcolm@redhat.com>]

On Wed, 2015-07-01 at 07:49 +0100, Dibyendu Majumdar wrote:
> On 1 July 2015 at 01:25, David Malcolm <dmalcolm@redhat.com> wrote:
> > Would it be useful to have some kind of error/warning about unused
> > rvalues?  (this would almost certainly be for post-5.2 at this point
> > though)   Perhaps specifically for gcc_jit_context_new_call, that one
> > seems to be a "gotcha".
> >
> > Something like:
> >
> >   extern void
> >   gcc_jit_context_set_bool_check_for_unused_rvalues (gcc_jit_context *ctxt,
> >                                                      int bool_value);
> >
> > issuing a hard error if enabled and there's an unused rvalue.
> >
> > (defaulting to off?  or maybe to on, if all valid client code runs OK
> > with it on?)
> >
> 
> Probably. I guess I will now be more careful about checking for this
> so hopefully I won't make the same mistake. So you may want to wait
> for other users' feedback before adding an API.
> 
> >> I will try to implement as many op codes as I can over the weekend and
> >> report back in case of issues.
> >
> > FWIW, the deadline for the GCC 5.2 release candidate is Friday, and I
> > need to take Friday off from the computer for family stuff, so
> > effectively the only remaining jit things to go into 5.2 will be
> > whatever we get into trunk, and backport in the next two days.
> >
> 
> Ok
> 
> > I believe the two most important issues for Ravi are:
> >
> > * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66546
> > ("No way to disable check for unreachable blocks")
> > This is fixed in trunk, with a new entrypoint you'll need to call:
> >      gcc_jit_context_set_bool_allow_unreachable_blocks
> > I anticipate backporting this to gcc-5-branch tomorrow.

Done: backported in gcc-5-branch as r225254.

> >
> > * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66700
> > ("Bogus gimplification of jit code using ptrs to functions", aka the
> > "Weird problem" thread)
> > I have a patch for this which I anticipate committing to trunk
> > and backporting to gcc-5-branch, both tomorrow.
> >

Done: committed to trunk as r225248 and to gcc-5-branch as r225258.

> Yes these are the must haves. Rest are all nice to have and can wait.

OK; thanks.  These will be in gcc 5.2, barring any unforeseen mess-ups.

> > Other issues affecting Ravi:
> >
> > * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66594
> > ("jitted code should use -mtune=native")
> > Sadly I don't have a clean fix for this yet, and I don't anticipate
> > having one by the 5.2 deadline.  There's a hackish workaround for x86_64
> > attached to the bug.

Still unlikely to be fixed for 5.2, sorry.


> > * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66628
> > ('jit: Provide a way to add arbitrary options to the toplev "command
> > line"')
> > Fixed in trunk; I anticipate backporting the fix to gcc-5-branch
> > tomorrow.   BTW, note that I don't think you can inject "-mtune=native"
> > this way.

Done: backported to gcc-5-branch as r225253.


> > See also:
> > https://gcc.gnu.org/bugzilla/showdependencytree.cgi?id=66627&hide_resolved=0
> >
> > plus various other patches I've already committed that I hope to
> > backport.
> >
> > Did I miss anything important to Ravi?
> >
> 
> No that's it so far.

Thanks.  I believe gcc 5.2 will contain Ravi's "must-have" bug-fixes.

Dave