See more answers below. On Thu, 2023-11-09 at 19:33 -0500, Antoni Boucher wrote: > > 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.
This detects the capabilities of the host that libgccjit is currently running on. > > > > > > > > > > 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. To add to this, libgccjit will just report that the feature is not detected when cross-compiling. > > > > > > > > > > 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. It does build. > > > > > > > > > > [...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 > > > > > >
