From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sender4-pp-o92.zoho.com (sender4-pp-o92.zoho.com [136.143.188.92]) by sourceware.org (Postfix) with ESMTPS id 8F22A384AB7E; Fri, 19 Apr 2024 12:34:45 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 8F22A384AB7E Authentication-Results: sourceware.org; dmarc=pass (p=reject dis=none) header.from=zoho.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=zoho.com ARC-Filter: OpenARC Filter v1.0.0 sourceware.org 8F22A384AB7E Authentication-Results: server2.sourceware.org; arc=pass smtp.remote-ip=136.143.188.92 ARC-Seal: i=2; a=rsa-sha256; d=sourceware.org; s=key; t=1713530087; cv=pass; b=RfKNmhFKD584FTDV0DERKsFp0Y+ZSEEHyxXCRSJb2wSyQsC0dBZW4MwSQRVvVMQmT+/IbnwY/d564I1TY+q/5KNAfJ3XSkSsZl31D+DP3xNxL4TJxArDSmLXRgxggLU7EJ7MAzo82haRF+7GnUAd39HZJ6G8mVAtz3G5vqSD4TE= ARC-Message-Signature: i=2; a=rsa-sha256; d=sourceware.org; s=key; t=1713530087; c=relaxed/simple; bh=UNJTaljj9sY2v4lbwEKapy1ykIoBc1bSp0pKBkLo1tQ=; h=DKIM-Signature:Message-ID:Date:MIME-Version:Subject:From:To; b=rTfqfUpqNr9qSta+LDy2ComIphnXyZBYLR6GkoRhYNDE4vYa+wlMvVEmEjNwcoezaBt7qzWGO8v1yx8svR9XKFjEbilENmCymdx+GY/XNZJeXU9o2PY/oEhwWi2rV7sESnT36bEc77q1oDKk7bNrcdhlXsZanDEN8WVrLGq7UI8= ARC-Authentication-Results: i=2; server2.sourceware.org ARC-Seal: i=1; a=rsa-sha256; t=1713530081; cv=none; d=zohomail.com; s=zohoarc; b=dSJDHv+MRbs8auLuwcMOTFYo2Etk8yR4wGB+XUKhFOpHsAxYzqXsZ9FD0KbBNeqR2oDK8DTUyRQ7kcPRp/NkF98H0eg6Ot4U2B9Yzc9iT8PVETYoOCvwrLa5GEGaO1Zz1UuP78+ySed+PXXHoSzPTqPe0fvtEFkTqIHLrFTBjpA= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1713530081; h=Content-Type:Content-Transfer-Encoding:Date:Date:From:From:In-Reply-To:MIME-Version:Message-ID:References:Subject:Subject:To:To:Message-Id:Reply-To:Cc; bh=JGz714we/7CMWlY6VjXC0sUOmzMuFCCRdNO2njqoY+A=; b=It0XRgbgIBSrd4UT3T6yN0qkZ0cRJmMlNEsS8yAoQ6gQ0JBXM329Wu1WLqewLoGgrxNPouwLGy8vg3lMWZ1TTWNkS2bkyO5mM7G2aaom9Yw7ymAZ9U4+mCxJCALkhBIkkcapF0Yo8jpMO8BGh2npRQcWsx1rFYDpvwL4rAyFm+k= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass header.i=zoho.com; spf=pass smtp.mailfrom=bouanto@zoho.com; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1713530081; s=zm2022; d=zoho.com; i=bouanto@zoho.com; h=Message-ID:Date:Date:MIME-Version:Subject:Subject:From:From:To:To:References:In-Reply-To:Content-Type:Content-Transfer-Encoding:Feedback-ID:Message-Id:Reply-To:Cc; bh=JGz714we/7CMWlY6VjXC0sUOmzMuFCCRdNO2njqoY+A=; b=cTp2nK2WAj1A2HXDF3/cBBkMfC1VnGN0eA5I0gZSGm+TJ8oNoo62xmCDkTArVETc WZhL0/mfr5cop3AYNbmhqwOdkRLbPiwQZ7Zu7AS7Q6AvQq5tky504txfS+qVQdTZ7b8 byFguHTFvToPVJ6IE7YDet1K0JZbzCLNZdIYLqPA= Received: by mx.zohomail.com with SMTPS id 1713530078717657.9712446415512; Fri, 19 Apr 2024 05:34:38 -0700 (PDT) Message-ID: Date: Fri, 19 Apr 2024 08:34:37 -0400 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: Frontend access to target features (was Re: [PATCH] libgccjit: Add ability to get CPU features) From: Antoni Boucher To: David Malcolm , jit@gcc.gnu.org, gcc-patches@gcc.gnu.org References: <8b0199d9835f568b7bcde41bf9432c21f604e489.camel@zoho.com> <755705e37731c4fbc3ab7eb1a96d8df0147bb002.camel@redhat.com> <6050c91ae34a2cdaeebd79ada9e2b9ffaf881e21.camel@zoho.com> <997ddb068ca13f755accd03f38141e56c87b84a7.camel@redhat.com> <1f7f229f-5d42-4bb6-9a47-0f3c630bea44@zoho.com> <4d106b99-20b4-466e-9c25-89e00df164f2@zoho.com> Content-Language: en-US, fr In-Reply-To: <4d106b99-20b4-466e-9c25-89e00df164f2@zoho.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Feedback-ID: rr080112288265a3eddfbb0f0edad01f8c000029544367d904aad2229b74fc2343646b1c7446c6996c068f7fb6:zu080112269f097296085aba450eda154f00000434e9008eef73cb2fb43b0b4f28de949605623da3a1faa7:rf0801122cc5f768ff80c837733883f58d000022e677d8ea8e53a1538b1ecdfd5872543f3a2f4716536ec75c775198be39:ZohoMail X-ZohoMailClient: External X-Spam-Status: No, score=-3.0 required=5.0 tests=BAYES_00,BODY_8BITS,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,KAM_SHORT,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: David: Ping. Le 2024-04-09 à 09 h 21, Antoni Boucher a écrit : > David: Ping. > > Le 2024-04-01 à 08 h 20, Antoni Boucher a écrit : >> David: Ping. >> >> Le 2024-03-19 à 07 h 03, Arthur Cohen a écrit : >>> Hi, >>> >>> On 3/5/24 16:09, David Malcolm wrote: >>>> 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. 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 >>>> >>>> [CCing Iain and Arthur re those patches; for reference, the patch being >>>> discussed is attached to : >>>> https://gcc.gnu.org/pipermail/jit/2024q1/001792.html ] >>>> >>>> One of my concerns about this patch is that we seem to be gaining code >>>> that's per-(frontend x config) which seems to be copied and pasted with >>>> a search and replace, which could lead to an M*N explosion. >>> >>> I think this is definitely already the case, and it would be worth >>> investigating if C/C++/Rust/jit can reuse a similar set of target >>> files, or how to factor them together. I imagine that all of these >>> components share similar needs for the targets they support. >>> >>>> >>>> Is there any real difference between the per-config code for the >>>> different frontends, or should there be a general "enumerate all >>>> features of the target" hook that's independent of the frontend? (but >>>> perhaps calls into it). >>>> >>>> Am I right in thinking that (rustc with default LLVM backend) has some >>>> set of feature strings that both (rustc with rustc_codegen_gcc) and >>>> gccrs are trying to emulate?  If so, is it presumably a goal that >>>> libgccjit gives identical results to gccrs?  If so, would it be crazy >>>> for libgccjit to consume e.g. config/i386/i386-rust.cc ? >>> >>> I think this would definitely make sense, and it could probably be >>> extended to other frontends. For the time being I think it makes >>> sense to try it out for gccrs and jit. But finding a fitting name >>> will be hard :) >>> >>> Best, >>> >>> Arthur >>> >>>> >>>> Dave >>>> >>>>> >>>>>> >>>>>> 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 >>>>>> >>>>> >>>>