From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from rock.gnat.com (rock.gnat.com [IPv6:2620:20:4000:0:a9e:1ff:fe9b:1d1]) by sourceware.org (Postfix) with ESMTPS id D694238983AD for ; Tue, 28 Jun 2022 13:33:14 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org D694238983AD Received: from localhost (localhost.localdomain [127.0.0.1]) by filtered-rock.gnat.com (Postfix) with ESMTP id 8DE321164EE; Tue, 28 Jun 2022 09:33:13 -0400 (EDT) X-Virus-Scanned: Debian amavisd-new at gnat.com Received: from rock.gnat.com ([127.0.0.1]) by localhost (rock.gnat.com [127.0.0.1]) (amavisd-new, port 10024) with LMTP id M36bLXpTqZPu; Tue, 28 Jun 2022 09:33:13 -0400 (EDT) Received: from free.home (tron.gnat.com [IPv6:2620:20:4000:0:46a8:42ff:fe0e:e294]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by rock.gnat.com (Postfix) with ESMTPS id 53B521164ED; Tue, 28 Jun 2022 09:33:13 -0400 (EDT) Received: from livre (livre.home [172.31.160.2]) by free.home (8.15.2/8.15.2) with ESMTPS id 25SDWsU8928764 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 28 Jun 2022 10:32:55 -0300 From: Alexandre Oliva To: Hans-Peter Nilsson Cc: gcc-patches@gcc.gnu.org Subject: Re: [PATCH] Support multilib-aware target lib flags self-specs overriding Organization: Free thinker, does not speak for AdaCore References: Errors-To: aoliva@lxoliva.fsfla.org Date: Tue, 28 Jun 2022 10:32:54 -0300 In-Reply-To: (Alexandre Oliva's message of "Fri, 03 Jun 2022 04:15:15 -0300") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.84 X-Spam-Status: No, score=-12.3 required=5.0 tests=BAYES_00, GIT_PATCH_0, KAM_DMARC_STATUS, SPF_HELO_NONE, SPF_PASS, 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 X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 28 Jun 2022 13:33:16 -0000 On Jun 3, 2022, Alexandre Oliva wrote: > On Jun 1, 2022, Hans-Peter Nilsson wrote: >> -fmultiflags? > That works for me. I favored -multiflags slightly, because the intended > use is for it to stand for other -m flags, but --multiflags AKA > -fmultiflags will do as well. > Now, is there interest in this feature? (As in, does it any make sense > for me to post a revised patch, or should I keep it downstream?) FTR, here's the patch I ended up with, adjusted to use -fmultiflags. Support multilib-aware target lib flags self-specs overriding This patch introduces -fmultiflags, short for multilib TFLAGS, as an option that does nothing by default, but that can be added to TFLAGS and mapped to useful options by driver self-specs. Regstrapped on x86_64-linux-gnu. Posted mainly FTR, but... I wouldn't mind putting it in, so... Ok to install? ;-) for gcc/ChangeLog * common.opt (fmultiflags): New. * doc/invoke.texi: Document it. * gcc.cc (driver_self_specs): Discard it. * opts.cc (common_handle_option): Ignore it in the driver. --- gcc/common.opt | 4 ++++ gcc/doc/invoke.texi | 30 +++++++++++++++++++++++++++++- gcc/gcc.cc | 6 +++++- gcc/opts.cc | 4 ++++ 4 files changed, 42 insertions(+), 2 deletions(-) diff --git a/gcc/common.opt b/gcc/common.opt index e7a51e882bade..814966c4562fe 100644 --- a/gcc/common.opt +++ b/gcc/common.opt @@ -2177,6 +2177,10 @@ fmove-loop-stores Common Var(flag_move_loop_stores) Optimization Move stores out of loops. +fmultiflags +Common Driver +Building block for specs-based multilib-aware TFLAGS. + fdce Common Var(flag_dce) Init(1) Optimization Use the RTL dead code elimination pass. diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index bde59ff047249..f9c53df37b28b 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -725,7 +725,7 @@ Objective-C and Objective-C++ Dialects}. -flto-report -flto-report-wpa -fmem-report-wpa @gol -fmem-report -fpre-ipa-mem-report -fpost-ipa-mem-report @gol -fopt-info -fopt-info-@var{options}@r{[}=@var{file}@r{]} @gol --fprofile-report @gol +-fmultiflags -fprofile-report @gol -frandom-seed=@var{string} -fsched-verbose=@var{n} @gol -fsel-sched-verbose -fsel-sched-dump-cfg -fsel-sched-pipelining-verbose @gol -fstats -fstack-usage -ftime-report -ftime-report-details @gol @@ -18927,6 +18927,34 @@ allocation for the WPA phase only. Makes the compiler print some statistics about permanent memory allocation before or after interprocedural optimization. +@item -fmultiflags +@opindex fmultiflags +This option enables multilib-aware @code{TFLAGS} to be used to build +target libraries with options different from those the compiler is +configured to use by default, through the use of specs (@xref{Spec +Files}) set up by compiler internals, by the target, or by builders at +configure time. + +Like @code{TFLAGS}, this allows the target libraries to be built for +portable baseline environments, while the compiler defaults to more +demanding ones. That's useful because users can easily override the +defaults the compiler is configured to use to build their own programs, +if the defaults are not ideal for their target environment, whereas +rebuilding the runtime libraries is usually not as easy or desirable. + +Unlike @code{TFLAGS}, the use of specs enables different flags to be +selected for different multilibs. The way to accomplish that is to +build with @samp{make TFLAGS=-fmultiflags}, after configuring +@samp{--with-specs=%@{fmultiflags:...@}}. + +This option is discarded by the driver once it's done processing driver +self spec. + +It is also useful to check that @code{TFLAGS} are being used to build +all target libraries, by configuring a non-bootstrap compiler +@samp{--with-specs='%@{!fmultiflags:%emissing TFLAGS@}'} and building +the compiler and target libraries. + @item -fprofile-report @opindex fprofile-report Makes the compiler print some statistics about consistency of the diff --git a/gcc/gcc.cc b/gcc/gcc.cc index 5cbb38560b266..24d3544e68140 100644 --- a/gcc/gcc.cc +++ b/gcc/gcc.cc @@ -1347,7 +1347,11 @@ static const char *const multilib_defaults_raw[] = MULTILIB_DEFAULTS; static const char *const driver_self_specs[] = { "%{fdump-final-insns:-fdump-final-insns=.} %report_bug = value; break; + case OPT_fmultiflags: + gcc_checking_assert (lang_mask == CL_DRIVER); + break; + default: /* If the flag was handled in a standard way, assume the lack of processing here is intentional. */ -- Alexandre Oliva, happy hacker https://FSFLA.org/blogs/lxo/ Free Software Activist GNU Toolchain Engineer Disinformation flourishes because many people care deeply about injustice but very few check the facts. 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