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From: "cvs-commit at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org> To: gdb-prs@sourceware.org Subject: [Bug rust/30116] "start" fails for Rust with new DWARF indexer Date: Sat, 18 Feb 2023 23:22:17 +0000 [thread overview] Message-ID: <bug-30116-4717-KmQtNj0dWE@http.sourceware.org/bugzilla/> (raw) In-Reply-To: <bug-30116-4717@http.sourceware.org/bugzilla/> https://sourceware.org/bugzilla/show_bug.cgi?id=30116 --- Comment #2 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Tom Tromey <tromey@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=47fe57c92810c7302bb80eafdec6f4345bcc69c8 commit 47fe57c92810c7302bb80eafdec6f4345bcc69c8 Author: Tom Tromey <tom@tromey.com> Date: Mon Feb 13 17:44:54 2023 -0700 Fix "start" for D, Rust, etc The new DWARF indexer broke "start" for some languages. For D, it is broken because, while the code in cooked_index_shard::add specifically excludes Ada, it fails to exclude D. This means that the C "main" will be detected as "main" here -- whereas what is intended is for the code in find_main_name to use d_main_name to find the name. The Rust compiler, on the other hand, uses DW_AT_main_subprogram. However, the code in dwarf2_build_psymtabs_hard fails to create a fully-qualified name, so the name always ends up as plain "main". For D and Ada, a very simple approach suffices: remove the check against "main" from cooked_index_shard::add. This also has the benefit of slightly speeding up DWARF indexing. I assume this approach will work for Pascal and Modula-2 as well, but I don't have a way to test those at present. For Rust, though, this is not sufficient. And, computing the fully-qualified name in dwarf2_build_psymtabs_hard will crash, because cooked_index_entry::full_name uses the canonical name -- and that is not computed until after canonicalization. However, we don't want to wait for canonicalization to be done before computing the main name. That would remove any benefit from doing canonicalization is the background. This patch solves this dilemma by noticing that languages using DW_AT_main_subprogram are, currently, disjoint from languages requiring canonicalization. Because of this, we can add a parameter to full_name to let us avoid crashes, slowdowns, and races here. This is kind of tricky and ugly, so I've tried to comment it sufficiently. While doing this, I had to change gdb.dwarf2/main-subprogram.exp. A different possibility here would be to ignore the canonicalization needs of C in this situation, because those only affect certain types. However, I chose this approach because the test case is artificial anyhow. A long time ago, in an earlier threading attempt, I changed the global current_language to be a function (hidden behind a macro) to let us attempt lazily computing the current language. Perhaps this approach could still be made to work. However, that also seemed rather tricky, more so than this patch. Reviewed-By: Andrew Burgess <aburgess@redhat.com> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30116 -- You are receiving this mail because: You are on the CC list for the bug.
next prev parent reply other threads:[~2023-02-18 23:22 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-02-12 16:25 [Bug rust/30116] New: " tromey at sourceware dot org 2023-02-12 16:25 ` [Bug rust/30116] " tromey at sourceware dot org 2023-02-14 0:39 ` tromey at sourceware dot org 2023-02-18 23:22 ` cvs-commit at gcc dot gnu.org [this message] 2023-02-18 23:30 ` cvs-commit at gcc dot gnu.org 2023-02-18 23:31 ` tromey at sourceware dot org
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