From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-x52d.google.com (mail-ed1-x52d.google.com [IPv6:2a00:1450:4864:20::52d]) by sourceware.org (Postfix) with ESMTPS id 364E7389040B for ; Tue, 12 Jan 2021 07:44:48 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 364E7389040B Received: by mail-ed1-x52d.google.com with SMTP id j16so1238480edr.0 for ; Mon, 11 Jan 2021 23:44:48 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=bjyO/GoEiL9+/dC3mmLM7FEWxYeXzH1FLE60T5kAtZs=; b=g64C2eZJ584GaAgeO1wycKFjk4DakyIwtsskGKLs3JhBWZIa1257WdVb15mcwIJ0kY uyW8pFTMJWOMJk6FyaQsjfiZsDgV5Guce0uDwJoiWWaWo+0IJL0MRozRnc3mKyzzGFET nAVOrmIVVboFMi0mQiKEsRp4Kt3wognmZHQS6cf9saSgaTcxWThBymA6gjuMyQp9JHp+ 7XaF5uilAC7YqyYPVRS8cmXAN+BKZSqSnhUJTjqPShEdksp0my3tpN9gklmjAUrUTLhR MaOO26psTJu6DSM5k7nkDdtjeEUgwhYyjDyR+3nvlqx1e2lKYPgYywahGyy2ox//7S1C vIFA== X-Gm-Message-State: AOAM530D/hnVPYkYblvfqvZOdw/GhodrpUBUk8SUwoRnXth8OPMYOXtR NJ95jmlpQh9mZFeQgPsm5N+KDBdwu/NcYKCx1xs= X-Google-Smtp-Source: ABdhPJxqchBwJ/JEWGxKN+l7hqRpXM2uqyYyEG/fLGQFgYC4zNpUPopCM+h8t6WnhlIYgqCt1errJbkguobTvdiiYAE= X-Received: by 2002:a50:f61b:: with SMTP id c27mr2341398edn.61.1610437487329; Mon, 11 Jan 2021 23:44:47 -0800 (PST) MIME-Version: 1.0 References: <20210111215657.3542216-1-dmalcolm@redhat.com> In-Reply-To: <20210111215657.3542216-1-dmalcolm@redhat.com> From: Richard Biener Date: Tue, 12 Jan 2021 08:44:36 +0100 Message-ID: Subject: Re: [PATCH] Handle fancy_abort before diagnostic initialization [PR98586] To: David Malcolm Cc: GCC Patches Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-9.5 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) 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, 12 Jan 2021 07:44:49 -0000 On Mon, Jan 11, 2021 at 10:57 PM David Malcolm via Gcc-patches wrote: > > If fancy_abort is called before the diagnostic subsystem is initialized, > internal_error will crash internally in a way that prevents a useful > message reaching the user. > > This can happen with libgccjit in the case of gcc_assert failures > that occur outside of the libgccjit mutex that guards the rest of > gcc's state, including global_dc (when global_dc may not be > initialized yet, or might be in use by another thread). > > I tried a few approaches to fixing this as noted in PR jit/98586 > e.g. using a temporary diagnostic_context and initializing it for > the call to internal_error, however the more code that runs, the > more chance there is for other errors to occur. > > The best fix appears to be to simply fall back to a minimal abort > implementation that only relies on i18n, as implemented by this > patch. > > Successfully bootstrapped & regrtested on x86_64-pc-linux-gnu. > > Is there a better way to fix this? If not I plan to push this > to master in a few days. The only other idea I can come up with is to somehow statically initialize global_dc to a minimal implementation to catch those. Otherwise your approach is entirely reasonable. Richard. > gcc/ChangeLog: > PR jit/98586 > * diagnostic.c (diagnostic_kind_text): Break out this array > from... > (diagnostic_build_prefix): ...here. > (fancy_abort): Detect when diagnostic_initialize has not yet been > called and fall back to a minimal implementation of printing the > ICE, rather than segfaulting in internal_error. > --- > gcc/diagnostic.c | 45 +++++++++++++++++++++++++++++++++++++++------ > 1 file changed, 39 insertions(+), 6 deletions(-) > > diff --git a/gcc/diagnostic.c b/gcc/diagnostic.c > index 4250bf96c8b..3be7748eb39 100644 > --- a/gcc/diagnostic.c > +++ b/gcc/diagnostic.c > @@ -431,6 +431,13 @@ diagnostic_get_location_text (diagnostic_context *context, > line_col, locus_ce); > } > > +static const char *const diagnostic_kind_text[] = { > +#define DEFINE_DIAGNOSTIC_KIND(K, T, C) (T), > +#include "diagnostic.def" > +#undef DEFINE_DIAGNOSTIC_KIND > + "must-not-happen" > +}; > + > /* Return a malloc'd string describing a location and the severity of the > diagnostic, e.g. "foo.c:42:10: error: ". The caller is responsible for > freeing the memory. */ > @@ -438,12 +445,6 @@ char * > diagnostic_build_prefix (diagnostic_context *context, > const diagnostic_info *diagnostic) > { > - static const char *const diagnostic_kind_text[] = { > -#define DEFINE_DIAGNOSTIC_KIND(K, T, C) (T), > -#include "diagnostic.def" > -#undef DEFINE_DIAGNOSTIC_KIND > - "must-not-happen" > - }; > gcc_assert (diagnostic->kind < DK_LAST_DIAGNOSTIC_KIND); > > const char *text = _(diagnostic_kind_text[diagnostic->kind]); > @@ -1832,6 +1833,38 @@ error_recursion (diagnostic_context *context) > void > fancy_abort (const char *file, int line, const char *function) > { > + /* If fancy_abort is called before the diagnostic subsystem is initialized, > + internal_error will crash internally in a way that prevents a > + useful message reaching the user. > + This can happen with libgccjit in the case of gcc_assert failures > + that occur outside of the libgccjit mutex that guards the rest of > + gcc's state, including global_dc (when global_dc may not be > + initialized yet, or might be in use by another thread). > + Handle such cases as gracefully as possible by falling back to a > + minimal abort handler that only relies on i18n. */ > + if (global_dc->printer == NULL) > + { > + /* Print the error message. */ > + fnotice (stderr, diagnostic_kind_text[DK_ICE]); > + fnotice (stderr, "in %s, at %s:%d", function, trim_filename (file), line); > + fputc ('\n', stderr); > + > + /* Attempt to print a backtrace. */ > + struct backtrace_state *state > + = backtrace_create_state (NULL, 0, bt_err_callback, NULL); > + int count = 0; > + if (state != NULL) > + backtrace_full (state, 2, bt_callback, bt_err_callback, > + (void *) &count); > + > + /* We can't call warn_if_plugins or emergency_dump_function as these > + rely on GCC state that might not be initialized, or might be in > + use by another thread. */ > + > + /* Abort the process. */ > + real_abort (); > + } > + > internal_error ("in %s, at %s:%d", function, trim_filename (file), line); > } > > -- > 2.26.2 >