Re: [PATCH] libgccjit: Fix float vector comparison

[Antoni Boucher <bouanto@zoho.com>]

Ping David:

Some more notes about the try/catch API:
I finally got unwinding implemented in rustc_codegen_gcc with the
following GCC patch:
https://github.com/antoyo/gcc/commit/fd603a3c715d3708f831cb637fbcc48bf4641859

It still requires clean-up, but you can have a look at it.
I'm still unsure for the CFG:
currently, it requires the finally to be terminated which would prevent
a finally reached through unwinding to work correctly; unless you call
unwind_resume, in which case, that would probably prevent a normal
finally (e.g. reached not by unwinding, but by falling off the try).
I'll try to not require the finally block to be terminated, but I
remember having issues making that work.

What are your thoughts on this? 

On Fri, 2022-12-02 at 09:29 -0500, Antoni Boucher wrote:
> On Thu, 2022-12-01 at 11:57 -0500, David Malcolm wrote:
> > On Thu, 2022-12-01 at 10:33 -0500, Antoni Boucher wrote:
> > > On Thu, 2022-12-01 at 10:25 -0500, David Malcolm wrote:
> > > > On Thu, 2022-12-01 at 10:01 -0500, Antoni Boucher wrote:
> > > > > Thanks, David.
> > > > > Since we're not in phase 1 anymore, do we need an approval
> > > > > before
> > > > > I
> > > > > merge like last year or can I merge immediately?
> > > > 
> > > > I think it counts as a bug fix and thus you can go ahead and
> > > > merge
> > > > (assuming you've done the usual testing).
> > > > 
> > > > > I also have many other patches (all in jit) that I need to
> > > > > prepare
> > > > > and
> > > > > post to this mailing list.
> > > > > What do you think?
> > > > 
> > > > Given that you're one of the main users of libgccjit I think
> > > > there's
> > > > a
> > > > case for stretching the deadlines a bit here.
> > > > 
> > > > Do you have a repo I can look at?
> > > 
> > > Yes! The commits are in my fork:
> > > https://github.com/antoyo/gcc
> > > 
> > > The only big one is the one adding support for target-dependent
> > > builtins:
> > > https://github.com/antoyo/gcc/commit/6d4313d4c02dd878f43917c978f299f5119330f0
> > > 
> > > Regarding this one, there's the issue that since we record the
> > > builtins
> > > on the first context run, we only have access to the builtins
> > > from
> > > the
> > > second run.
> > > Do you have any idea how to fix this?
> > > Or do you consider this is acceptable?
> > 
> > This is implemented behind the new
> > gcc_jit_context_get_target_builtin_function entrypoint, right?
> 
> Yes.
> 
> > 
> > If so, perhaps that recording::context::get_target_builtin_function
> > could detect if it's the first time it's been called on this
> > context,
> > and if so make a playback::context to do the detection?  That way
> > it
> > would be transparent to the user, and work first time.
> 
> Oh, the issue is actually with the type reflection API and also the
> type checking of function calls, so it's in the recording phase.
> While I could think of a workaround for the type checking (e.g.
> delayed
> type checking at the playback phase), I could not think of any better
> solution for the type reflection.
> 
> > 
> > 
> > I see you have patches to add function and variable attributes; I
> > wonder if this would be cleaner internally if there was a
> > recording::attribute class, rather than the std::pair currently in
> > use
> > (some attributes have int arguments rather than string, others have
> > multiple args).
> > 
> > I also wondered if a "gcc_jit_attribute" type could be exposed to
> > the
> > user, e.g.:
> > 
> >   attr1 = gcc_jit_context_new_attribute (ctxt, "noreturn");
> >   attr2 = gcc_jit_context_new_attribute_with_string (ctxt, "alias",
> > "__foo");
> >   gcc_jit_function_add_attribute (ctxt, attr1);
> >   gcc_jit_function_add_attribute (ctxt, attr2);
> > 
> > or somesuch?  But I think the API you currently have is OK.
> 
> Thanks for the suggestion; I'll look into that.
> 
> > 
> > 
> > > 
> > > I also have a WIP branch which adds support for try/catch:
> > > https://github.com/antoyo/gcc/commit/6219339fcacb079431596a0bc6cf8d430a1bd5a1
> > > I'm not sure if this one is going to be ready soon or not.
> > 
> > I see that the new entrypoints have e.g.:
> > 
> > /* Add a try/catch statement.
> >    This is equivalent to this C++ code:
> >      try {
> >         try_block
> >      }
> >      catch {
> >         catch_block
> >      }
> > */
> > 
> > void
> > gcc_jit_block_add_try_catch (gcc_jit_block *block,
> >                              gcc_jit_location *loc,
> >                              gcc_jit_block *try_block,
> >                              gcc_jit_block *catch_block);
> > 
> > but I'm not sure how this is meant to interact with the CFG-like
> > model
> > used by the rest of the gcc_jit_block_* API.  What happens at the
> > end
> > of the blocks?  Does the generated code use the C++ ABI for
> > exception-
> > handling?
> 
> Currently, it requires the try and catch blocks to be terminated, but
> also require the block containing the try/catch to be terminated.
> That doesn't make sense.
> Would it be OK if it doesn't require the try and catch blocks to be
> terminated?
> 
> For the ABI, I'm not sure it's necessarily tied to C++, but I might
> be
> wrong. From what I understand, GCC will use the dwarf-2 exception
> handling model if it's available or the sjlj otherwise (perhaps that
> can be configured).
> And the user can change the personality function via the API I added.
> 
> Thanks for your feedback.
> 
> > 
> > Dave
> > 
> > > 
> > > Thanks.
> > > 
> > > > 
> > > > Dave
> > > > 
> > > > 
> > > > > 
> > > > > On Thu, 2022-12-01 at 09:28 -0500, David Malcolm wrote:
> > > > > > On Sun, 2022-11-20 at 14:03 -0500, Antoni Boucher via Jit
> > > > > > wrote:
> > > > > > > Hi.
> > > > > > > This fixes bug 107770.
> > > > > > > Thanks for the review.
> > > > > > 
> > > > > > Thanks, the patch looks good to me.
> > > > > > 
> > > > > > Dave
> > > > > > 
> > > > > 
> > > > 
> > > 
> > 
>