From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 19233 invoked by alias); 1 Jun 2015 12:05:36 -0000 Mailing-List: contact gdb-prs-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-prs-owner@sourceware.org Received: (qmail 19130 invoked by uid 55); 1 Jun 2015 12:05:35 -0000 From: "cvs-commit at gcc dot gnu.org" To: gdb-prs@sourceware.org Subject: [Bug symtab/18392] ../../gdb/dwarf2loc.c:834: internal-error: chain_candidate: Assertion `result->callers + result->callees < result->length' failed Date: Mon, 01 Jun 2015 12:05:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gdb X-Bugzilla-Component: symtab X-Bugzilla-Version: 7.9 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: cvs-commit at gcc dot gnu.org X-Bugzilla-Status: NEW X-Bugzilla-Resolution: X-Bugzilla-Priority: P2 X-Bugzilla-Assigned-To: unassigned at sourceware dot org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Bugzilla-URL: http://sourceware.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-SW-Source: 2015-q2/txt/msg00348.txt.bz2 https://sourceware.org/bugzilla/show_bug.cgi?id=18392 --- Comment #1 from cvs-commit at gcc dot gnu.org --- The master branch has been updated by Jan Kratochvil : https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=e0619de699ae6e86d8b93fa96a7668aef2e9636a commit e0619de699ae6e86d8b93fa96a7668aef2e9636a Author: Jan Kratochvil Date: Mon Jun 1 14:02:34 2015 +0200 PR symtab/18392 Initially there is some chain (let's say the longest one but that doe snot matter). Consequently its elements from the middle are being removed and there remains only some few unambiguous top and bottom ones. The original idea why the comparison should be sharp ("<") was that if there are multiple chains like (0xaddr show jmp instruction address): main(0x100) -> a(0x200) -> d(0x400) main(0x100) -> a(0x200) -> c(0x300) -> d(0x400) then - such situation cannot exist - if two jmp instructions in "a" have the same address they must also jump to the same address (*). (*) jump to a computed address would be never considered for the DWARF tail-call records. So there could be: main(0x100) -> a(0x200) -> d(0x400) main(0x100) -> a(0x270) -> c(0x300) -> d(0x400) But then "a" frame itself is ambiguous and it must not be displayed. I did not realize that there can be self-tail-call: main(0x100) -> a(0x200) -> d(0x400) main(0x100) -> a(0x280) -> a(0x200) -> d(0x400) which intersects to: main(0x100) -> ? -> a(0x200) -> d(0x400) And so if the first chain was chosen the main(0x100) -> a(0x200) -> d(0x400) then the final intersection has callers+callees==length. > for example, if CALLERS is 3 and > CALLEES is 2, what does the chain look like? main(0x100) -> x(0x150) -> y(0x200) -> ? -> a(0x200) -> d(0x400) And if LENGTH is 7 then: call_site[0] = main(0x100) call_site[1] = x(0x150) call_site[2] = y(0x200) call_site[3] = garbage call_site[4] = garbage call_site[5] = a(0x200) call_site[6] = d(0x400) gdb/ChangeLog 2015-06-01 Andreas Schwab Jan Kratochvil PR symtab/18392 * dwarf2-frame-tailcall.c (pretended_chain_levels): Correct assertion. * dwarf2loc.c (chain_candidate): Likewise. gdb/testsuite/ChangeLog 2015-06-01 Jan Kratochvil PR symtab/18392 * gdb.arch/amd64-tailcall-self.S: New file. * gdb.arch/amd64-tailcall-self.c: New file. * gdb.arch/amd64-tailcall-self.exp: New file. -- You are receiving this mail because: You are on the CC list for the bug.