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From: "iains at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug bootstrap/100340] Bootstrap fails with Clang 12.0.5 (XCode 12.5)
Date: Fri, 30 Apr 2021 06:55:00 +0000 [thread overview]
Message-ID: <bug-100340-4-dw1Os4LKT9@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-100340-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100340
--- Comment #6 from Iain Sandoe <iains at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #5)
> Does it work when you use STAGE1_CFLAGS="-O0" (I think clang defaults to
> optimizing?). To rule out compare-debug issues also try
> --without-build-config
The reason for the fail is that the assembler (clang -cc1as) is assembling
branch instructions with differing lengths between the debug and non-debug
cases.
The code is not actually wrong in either case - it simply looks like branch
relaxation has been enabled in one case and not the other.
However this is not in response to changed command line options (so it is an
internal decision in the assembler, probably as a result of detecting either
.loc directives or presence/absence of Lxxxx local labels between branch and
its destination.).
I am discussing with OSS folks at Apple whether this is an intentional change
(i.e to produce better optimised code) or an accidental one.
Short-term workarounds:
1. (re-)install xcode 12.4 command line tools and select them for use
2. disable debug comparison in the bootstrap ( --without-build-config )
next prev parent reply other threads:[~2021-04-30 6:55 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-29 19:48 [Bug bootstrap/100340] New: " juergen.reuter at desy dot de
2021-04-29 19:49 ` [Bug bootstrap/100340] " juergen.reuter at desy dot de
2021-04-29 21:17 ` juergen.reuter at desy dot de
2021-04-29 23:38 ` dominiq at lps dot ens.fr
2021-04-30 5:09 ` juergen.reuter at desy dot de
2021-04-30 6:47 ` rguenth at gcc dot gnu.org
2021-04-30 6:55 ` iains at gcc dot gnu.org [this message]
2021-04-30 8:38 ` [Bug target/100340] " iains at gcc dot gnu.org
2021-04-30 12:09 ` juergen.reuter at desy dot de
2021-05-25 16:25 ` iains at gcc dot gnu.org
2021-07-29 14:49 ` matthew.thompson at nasa dot gov
2021-07-29 15:40 ` iains at gcc dot gnu.org
2021-07-29 20:31 ` juergen.reuter at desy dot de
2021-07-30 15:53 ` jonesc at hep dot phy.cam.ac.uk
2021-07-30 15:55 ` jonesc at hep dot phy.cam.ac.uk
2021-07-30 16:23 ` iains at gcc dot gnu.org
2021-08-02 13:36 ` matthew.thompson at nasa dot gov
2021-08-02 13:39 ` jonesc at hep dot phy.cam.ac.uk
2021-08-02 13:42 ` jonesc at hep dot phy.cam.ac.uk
2021-08-02 13:43 ` matthew.thompson at nasa dot gov
2021-08-02 14:17 ` iains at gcc dot gnu.org
2021-08-04 15:45 ` iains at gcc dot gnu.org
2021-08-17 18:39 ` cvs-commit at gcc dot gnu.org
2021-08-17 18:42 ` iains at gcc dot gnu.org
2021-09-27 17:10 ` matthew.thompson at nasa dot gov
2021-09-27 17:59 ` iains at gcc dot gnu.org
2021-10-02 22:51 ` fink at snaggledworks dot com
2021-10-13 19:59 ` cvs-commit at gcc dot gnu.org
2021-11-29 19:00 ` egallager at gcc dot gnu.org
2022-04-19 10:51 ` kirill at korins dot ky
2022-04-19 11:08 ` iains at gcc dot gnu.org
2022-04-19 11:45 ` kirill at korins dot ky
2022-05-27 9:04 ` rguenth at gcc dot gnu.org
2022-05-27 9:29 ` iains at gcc dot gnu.org
2022-05-29 19:03 ` cvs-commit at gcc dot gnu.org
2022-05-29 19:21 ` iains at gcc dot gnu.org
2022-07-27 17:12 ` egallager at gcc dot gnu.org
2022-07-27 18:18 ` iains at gcc dot gnu.org
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