From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by sourceware.org (Postfix) with ESMTP id 8A4FC3858D1E for ; Tue, 18 Apr 2023 11:14:29 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 8A4FC3858D1E Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D5A07168F; Tue, 18 Apr 2023 04:15:12 -0700 (PDT) Received: from localhost (e121540-lin.manchester.arm.com [10.32.110.72]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 79D0C3F5A1; Tue, 18 Apr 2023 04:14:28 -0700 (PDT) From: Richard Sandiford To: "Victor L. Do Nascimento" Mail-Followup-To: "Victor L. Do Nascimento" ,, , richard.sandiford@arm.com Cc: , Subject: Re: [PATCH] constraint: fix relaxed memory and repeated constraint handling References: Date: Tue, 18 Apr 2023 12:14:27 +0100 In-Reply-To: (Victor L. Do Nascimento's message of "Tue, 18 Apr 2023 11:13:55 +0100") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Spam-Status: No, score=-31.0 required=5.0 tests=BAYES_00,GIT_PATCH_0,KAM_DMARC_NONE,KAM_DMARC_STATUS,KAM_LAZY_DOMAIN_SECURITY,SPF_HELO_NONE,SPF_NONE,TXREP,T_SCC_BODY_TEXT_LINE 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: "Victor L. Do Nascimento" writes: > The function `constrain_operands' lacked the logic to consider relaxed > memory constraints when "traditional" memory constraints were not > satisfied, creating potential issues as observed during the reload > compilation pass. > > In addition, it was observed that while `constrain_operands' chooses > to disregard constraints when more than one alternative is provided, > e.g. "m,r" using CONSTRAINT__UNKNOWN, it has no checks in place to > determine whether the multiple constraints in a given string are in > fact repetitions of the same constraint and should thus in fact be > treated as a single constraint, as ought to be the case for something > like "m,m". > > Both of these issues are dealt with here, thus ensuring that we get > appropriate pattern matching. > > Tested on aarch64-linux-gnu & x86_64-linux-gnu. OK to install? > > Victor > > gcc/ > * lra-constraints.cc (constraint_unique): New. > (process_address_1): Apply constraint_unique test. > * recog.cc (constrain_operands): Allow relaxed memory > constaints. > --- > gcc/lra-constraints.cc | 40 +++++++++++++++++++++++++++++++++++++--- > gcc/recog.cc | 3 ++- > 2 files changed, 39 insertions(+), 4 deletions(-) > > diff --git a/gcc/lra-constraints.cc b/gcc/lra-constraints.cc > index dd4f68bbfc0..6a13e64d7e1 100644 > --- a/gcc/lra-constraints.cc > +++ b/gcc/lra-constraints.cc > @@ -3448,6 +3448,42 @@ skip_constraint_modifiers (const char *str) > } > } > > +/* Takes a string of 0 or more comma-separated constraints and the > + constraint_num correspondig to the first constraint. When more corresponding > + than one constraint present, evaluate whether they all correspond is present > + to a single, repeated constraint (e.g. "r,r") or whether we have > + more than one distinct constraints (e.g. "r,m"). */ > +static bool > +constraint_unique (const char *cstr) > +{ > + enum constraint_num ca, cb; > + ca = CONSTRAINT__UNKNOWN; > + for (;;) > + { > + cstr = skip_constraint_modifiers (cstr); > + if (*cstr == '\0' || *cstr == ',') > + cb = CONSTRAINT_X; > + else > + { > + cb = lookup_constraint (cstr); > + if (cb == CONSTRAINT__UNKNOWN) > + return false; > + cstr += CONSTRAINT_LEN (cstr[0], cstr); > + } > + /* Treat the special case of an uninitialized ca. */ Maybe: /* Handle the first iteration of the loop. */ > + if (ca == CONSTRAINT__UNKNOWN) > + ca = cb; > + /* Treat the general case of comparing ca with subsequent > + constraints. */ s/Treat/Handle/ OK with those changes, thanks. Richard > + else if (ca != cb) > + return false; > + if (*cstr == '\0') > + return true; > + if (*cstr == ',') > + cstr += 1; > + } > +} > + > /* Major function to make reloads for an address in operand NOP or > check its correctness (If CHECK_ONLY_P is true). The supported > cases are: > @@ -3507,9 +3543,7 @@ process_address_1 (int nop, bool check_only_p, > operand has one address constraint, probably all others constraints are > address ones. */ > if (constraint[0] != '\0' && get_constraint_type (cn) != CT_ADDRESS > - && *skip_constraint_modifiers (constraint > - + CONSTRAINT_LEN (constraint[0], > - constraint)) != '\0') > + && !constraint_unique (constraint)) > cn = CONSTRAINT__UNKNOWN; > if (insn_extra_address_constraint (cn) > /* When we find an asm operand with an address constraint that > diff --git a/gcc/recog.cc b/gcc/recog.cc > index 200cf4214f1..3ddeab59d92 100644 > --- a/gcc/recog.cc > +++ b/gcc/recog.cc > @@ -3234,7 +3234,8 @@ constrain_operands (int strict, alternative_mask alternatives) > else if (constraint_satisfied_p (op, cn)) > win = 1; > > - else if (insn_extra_memory_constraint (cn) > + else if ((insn_extra_memory_constraint (cn) > + || insn_extra_relaxed_memory_constraint (cn)) > /* Every memory operand can be reloaded to fit. */ > && ((strict < 0 && MEM_P (op)) > /* Before reload, accept what reload can turn