From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by sourceware.org (Postfix) with ESMTPS id 62EBF3858D20 for ; Fri, 27 Jan 2023 08:57:11 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 62EBF3858D20 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1674809831; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:in-reply-to:in-reply-to: references:references; bh=Wj0e/nP1OhjrdbaPH3mP4xj1ZLSQ5EyUX7vn5CmNTPA=; b=NpeJ6SPlVXzfJfeztqugTa6b+YXCTXoG0HeTq7JZ7RIWXVDuXb0PA7jEa+AnuMFH2De8z6 EXbHSPlzcUBrIn+bwyjq6A6buA5VlFegeXgeBeKkRTDGeyOsqJoIkLAItvHKS/P8/+XTTT HokuvWq/fhi3oU5W95IZRJILt5dr6B8= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-614-gHEqbNYCOveBOyfuNeGMBw-1; Fri, 27 Jan 2023 03:57:07 -0500 X-MC-Unique: gHEqbNYCOveBOyfuNeGMBw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 67F05802C18; Fri, 27 Jan 2023 08:57:07 +0000 (UTC) Received: from tucnak.zalov.cz (unknown [10.39.192.223]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 20C497AD4; Fri, 27 Jan 2023 08:57:07 +0000 (UTC) Received: from tucnak.zalov.cz (localhost [127.0.0.1]) by tucnak.zalov.cz (8.17.1/8.17.1) with ESMTPS id 30R8v4j2681216 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Fri, 27 Jan 2023 09:57:04 +0100 Received: (from jakub@localhost) by tucnak.zalov.cz (8.17.1/8.17.1/Submit) id 30R8v2Jm681215; Fri, 27 Jan 2023 09:57:02 +0100 Date: Fri, 27 Jan 2023 09:57:02 +0100 From: Jakub Jelinek To: Richard Biener Cc: Jeff Law , Andrew Pinski , Patrick Palka , gcc-patches@gcc.gnu.org Subject: Re: [PATCH] tree: Fix up tree_code_{length,type} Message-ID: Reply-To: Jakub Jelinek References: <1668794731-9349-1-git-send-email-apinski@marvell.com> MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Spam-Status: No, score=-3.5 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_NONE,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: On Fri, Jan 27, 2023 at 07:42:39AM +0000, Richard Biener wrote: > > BTW, wonder if tree_code_type couldn't be an array of unsigned char > > elements rather than enum tree_code_class and we'd then cast it > > to the enum in the macro, that would shrink that array from 1496 bytes > > to 374. Of course, that sounds like stage1 material. > > One could argue the same way for this patch (and instead revert), Well, this patch is in fact a conditional reversion (revert for C++11/14, add one keyword to 2 declarations otherwise). > I'd say if we tweak this now then tweak it to the maximum extent? > Isn't sth like 'enum unsigned char tree_code_class' now possible? > (and a static assert the enum values all fit, though that would > be diagnosed anyway?) C++11 indeed has enum tree_code_class : unsigned char { tcc_exceptional, ... tcc_expression }; and one indeed gets an error if some enumerator doesn't fit. The problem I see with this is that the type is 8-bit everywhere, which I'd be afraid could cause worse code generation (of course, one would need to try to see how much; e.g. build the compiler unmodified, with the unsigned char array plus explicit casts from the array and finally with unsigned char as underlying type). When passing around enum tree_code_class etc., it is fine if it is 32-bit. And there isn't a way to create an enum with different underlying type but with the same enumerators as in another enum. Perhaps for tree_code_class we could away with the underlying type because it is mostly used in the macros which immediately compare it, in gcc/*.cc just in the following explicitly: expr.cc:get_def_for_expr_class (tree name, enum tree_code_class tclass) fold-const.cc: enum tree_code_class tclass; fold-const.cc: enum tree_code_class tclass = TREE_CODE_CLASS (code); fold-const.cc: enum tree_code_class tclass = TREE_CODE_CLASS (code); fold-const.cc: enum tree_code_class kind = TREE_CODE_CLASS (code); fold-const.cc: enum tree_code_class kind = TREE_CODE_CLASS (code); fold-const.cc: enum tree_code_class kind = TREE_CODE_CLASS (code); fold-const.cc: enum tree_code_class kind = TREE_CODE_CLASS (code); gimple-fold.cc: enum tree_code_class kind = TREE_CODE_CLASS (subcode); print-tree.cc: enum tree_code_class tclass; print-tree.cc: enum tree_code_class tclass; tree.cc: These must correspond to the tree_code_class entries. */ tree.cc:const char *const tree_code_class_strings[] = tree.cc: enum tree_code_class type = TREE_CODE_CLASS (code); tree.cc: enum tree_code_class type = TREE_CODE_CLASS (code); tree.cc:tree_class_check_failed (const_tree node, const enum tree_code_class cl, tree.cc:tree_not_class_check_failed (const_tree node, const enum tree_code_class cl, tree.cc: const enum tree_code_class c = TREE_CODE_CLASS (TREE_CODE (t)); tree.cc: const enum tree_code_class c = TREE_CODE_CLASS (TREE_CODE (t)); tree-dump.cc: enum tree_code_class code_class; tree-inline.cc: enum tree_code_class cl = TREE_CODE_CLASS (code); tree-pretty-print.cc: enum tree_code_class tclass; tree-ssa-live.cc: enum tree_code_class c = TREE_CODE_CLASS (TREE_CODE (t)); tree-ssa-operands.cc: enum tree_code_class codeclass; But as I said, one would need to watch for code generation at least on a couple of common hosts, and while x86_64 should be one of them, it might have bigger effects on others as x86 has byte comparison etc. instructions. > > > 2023-01-26 Patrick Palka > > Jakub Jelinek > > > > * tree-core.h (tree_code_type, tree_code_length): For > > C++17 and later, add inline keyword, otherwise don't define > > the arrays, but declare extern arrays. > > * tree.cc (tree_code_type, tree_code_length): Define these > > arrays for C++14 and older. > > > > --- gcc/tree-core.h.jj 2023-01-02 09:32:31.188158094 +0100 > > +++ gcc/tree-core.h 2023-01-26 16:02:34.212113251 +0100 > > @@ -2284,17 +2284,20 @@ struct floatn_type_info { > > /* Matrix describing the structures contained in a given tree code. */ > > extern bool tree_contains_struct[MAX_TREE_CODES][64]; > > > > +/* Class of tree given its code. */ > > +#if __cpp_inline_variables >= 201606L > > #define DEFTREECODE(SYM, NAME, TYPE, LENGTH) TYPE, > > #define END_OF_BASE_TREE_CODES tcc_exceptional, > > > > - > > -/* Class of tree given its code. */ > > -constexpr enum tree_code_class tree_code_type[] = { > > +constexpr inline enum tree_code_class tree_code_type[] = { > > #include "all-tree.def" > > }; > > Do we need an explicit external definition somewhere when > constant folding isn't possible? > > Otherwise looks good to me. > > Thanks, > Richard. > > > #undef DEFTREECODE > > #undef END_OF_BASE_TREE_CODES > > +#else > > +extern const enum tree_code_class tree_code_type[]; There is one here for the C++11 and C++14 cases. For C++17 and later it isn't needed, constexpr inline enum tree_code_class tree_code_type[] = { ... }; means this is a comdat variable in all TUs which need non-ODR uses of it (tree_code_type[23] evaluates to constant expression, but tree_code_type[x] or &tree_code_type[23] etc. often don't and then the comdat var is emitted and all TUs share one copy of the variable. Jakub