From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 29739 invoked by alias); 16 Jun 2012 16:33:23 -0000 Received: (qmail 29716 invoked by uid 22791); 16 Jun 2012 16:33:21 -0000 X-SWARE-Spam-Status: No, hits=-3.7 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00,KHOP_THREADED,TW_MJ X-Spam-Check-By: sourceware.org Received: from localhost (HELO sourceware.org) (127.0.0.1) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Sat, 16 Jun 2012 16:32:59 +0000 From: "fche at redhat dot com" To: systemtap@sourceware.org Subject: [Bug translator/6941] better prologue heuristics needed for userspace (non-regparm) Date: Sat, 16 Jun 2012 16:33:00 -0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: systemtap X-Bugzilla-Component: translator X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: fche at redhat dot com X-Bugzilla-Status: NEW X-Bugzilla-Priority: P2 X-Bugzilla-Assigned-To: systemtap at sourceware dot org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Changed-Fields: CC Message-ID: In-Reply-To: References: X-Bugzilla-URL: http://sourceware.org/bugzilla/ Auto-Submitted: auto-generated Content-Type: text/plain; charset="UTF-8" MIME-Version: 1.0 Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org X-SW-Source: 2012-q2/txt/msg00276.txt.bz2 http://sourceware.org/bugzilla/show_bug.cgi?id=6941 Frank Ch. Eigler changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |jan.kratochvil at redhat | |dot com, mjw at redhat dot | |com --- Comment #3 from Frank Ch. Eigler 2012-06-16 16:32:58 UTC --- With gcc VTA, prologue searching at -O2 is becoming unnecessary. However, at -O0 it is becoming essential, for gcc does not run VTA processing at -O0, and the dwarf location list data it emits is only accurate in the post-prologue section. So we need to figure out whether the given target executable was built with -O0, and then perform proper prologue search heuristics. To find out -O*, one can look at the DW_AT_producer of the DW_TAG_compile_unit,; recent gcc emits the compiler option list in there. We can look for the absence of -O[123] and/or the presence of -O0, or -fno-var-tracking. It's a heuristic, but so there. See gdb's dwarf2read.c:process_full_comp_unit() to see its set of related heuristics. See gdb's symtab.c:skip_prologue_sal() and skip_prologue_using_lineinfo() for the actual prologue-skipping heuristics, which are similar to our own in dwflpp.cxx:resolve_prologue_endings(). -- Configure bugmail: http://sourceware.org/bugzilla/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are the assignee for the bug.