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[binutils-gdb] PR symtab/18392
- From: sergiodj+buildbot at redhat dot com
- To: gdb-testers at sourceware dot org
- Date: Mon, 01 Jun 2015 08:39:54 -0400
- Subject: [binutils-gdb] PR symtab/18392
- Authentication-results: sourceware.org; auth=none
*** TEST RESULTS FOR COMMIT e0619de699ae6e86d8b93fa96a7668aef2e9636a ***
Author: Jan Kratochvil <jan.kratochvil@redhat.com>
Branch: master
Commit: e0619de699ae6e86d8b93fa96a7668aef2e9636a
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 <schwab@linux-m68k.org>
Jan Kratochvil <jan.kratochvil@redhat.com>
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 <jan.kratochvil@redhat.com>
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.
- Follow-Ups:
- Failures on Debian-i686, branch master
- Failures on Debian-i686-native-gdbserver, branch master
- Failures on Debian-i686-native-extended-gdbserver, branch master
- Failures on Fedora-ppc64be-cc-with-index, branch master
- Failures on Fedora-s390x-m64, branch master
- Failures on Debian-x86_64-m64, branch master
- Failures on Fedora-i686, branch master
- Failures on Fedora-x86_64-m32, branch master
- Failures on Fedora-x86_64-cc-with-index, branch master
- Failures on Fedora-x86_64-native-gdbserver-m64, branch master
- Failures on Fedora-ppc64le-native-extended-gdbserver-m64, branch master
- Failures on Fedora-ppc64le-cc-with-index, branch master