Hi. See answers below. On Thu, 2023-11-09 at 18:04 -0500, David Malcolm wrote: > On Thu, 2023-11-09 at 17:27 -0500, Antoni Boucher wrote: > > Hi. > > This patch adds support for getting the CPU features in libgccjit > > (bug > > 112466) > > > > There's a TODO in the test: > > I'm not sure how to test that gcc_jit_target_info_arch returns the > > correct value since it is dependant on the CPU. > > Any idea on how to improve this? > > > > Also, I created a CStringHash to be able to have a > > std::unordered_set<const char *>. Is there any built-in way of > > doing > > this? > > Thanks for the patch. > > Some high-level questions: > > Is this specifically about detecting capabilities of the host that > libgccjit is currently running on? or how the target was configured > when libgccjit was built?
I'm less sure about this part. I'll need to do more tests. > > One of the benefits of libgccjit is that, in theory, we support all > of > the targets that GCC already supports. Does this patch change that, > or > is this more about giving client code the ability to determine > capabilities of the specific host being compiled for? This should not change that. If it does, this is a bug. > > I'm nervous about having per-target jit code. Presumably there's a > reason that we can't reuse existing target logic here - can you > please > describe what the problem is. I see that the ChangeLog has: > > > * config/i386/i386-jit.cc: New file. > > where i386-jit.cc has almost 200 lines of nontrivial code. Where did > this come from? Did you base it on existing code in our source tree, > making modifications to fit the new internal API, or did you write it > from scratch? In either case, how onerous would this be for other > targets? This was mostly copied from the same code done for the Rust and D frontends. See this commit and the following: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=b1c06fd9723453dd2b2ec306684cb806dc2b4fbb The equivalent to i386-jit.cc is there: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=22e3557e2d52f129f2bbfdc98688b945dba28dc9 > > I'm not at expert at target hooks (or at the i386 backend), so if we > do > go with this approach I'd want someone else to review those parts of > the patch. > > Have you verified that GCC builds with this patch with jit *not* > enabled in the enabled languages? I will do. > > [...snip...] > > A nitpick: > > > +.. function:: const char * \ > > + gcc_jit_target_info_arch (gcc_jit_target_info *info) > > + > > + Get the architecture of the currently running CPU. > > What does this string look like? > How long does the pointer remain valid? It's the march string, like "znver2", for instance. It remains valid until we free the gcc_jit_target_info object. > > Thanks again; hope the above makes sense > Dave >
