[Bug debug/42918] New: "-fcompare-debug failure" with "-O2 -ftracer" (2)

[Bug debug/42918] New: "-fcompare-debug failure" with "-O2 -ftracer" (2)

[zsojka at seznam dot cz]

Command line:
gcc -O2 -ftracer -fcompare-debug -c testcase.c

Tested revisions:
r156367 - crash
r155609 - crash
r154830 - crash
r153685 - crash

Output:
$ /mnt/svn/gcc-trunk/binary-156367-lto/bin/gcc -O2 -ftracer -fcompare-debug -c
testcase.c
gcc: testcase.c: -fcompare-debug failure (length)


-- 
           Summary: "-fcompare-debug failure" with "-O2 -ftracer" (2)
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: zsojka at seznam dot cz
  GCC host triplet: x86(_64)-pc-linux-gnu
GCC target triplet: x86(_64)-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42918

[Bug debug/42918] "-fcompare-debug failure" with "-O2 -ftracer" (2)

[zsojka at seznam dot cz]

------- Comment #1 from zsojka at seznam dot cz  2010-01-31 22:53 -------
Created an attachment (id=19768)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=19768&action=view)
reduced testcase

Command line:
gcc -O2 -ftracer -fcompare-debug -c pr42918.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42918

[Bug debug/42918] [4.5 Regression] "-fcompare-debug failure" with "-O2 -ftracer" (2)

[pinskia at gcc dot gnu dot org]

-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |ice-on-valid-code, wrong-
                   |                            |code
            Summary|"-fcompare-debug failure"   |[4.5 Regression] "-fcompare-
                   |with "-O2 -ftracer" (2)     |debug failure" with "-O2 -
                   |                            |ftracer" (2)
   Target Milestone|---                         |4.5.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42918

[Bug debug/42918] [4.5 Regression] "-fcompare-debug failure" with "-O2 -ftracer" (2)

[rguenth at gcc dot gnu dot org]

------- Comment #2 from rguenth at gcc dot gnu dot org  2010-02-11 16:53 -------
Confirmed.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
           Priority|P3                          |P1
   Last reconfirmed|0000-00-00 00:00:00         |2010-02-11 16:53:46
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42918

[Bug debug/42918] [4.5 Regression] "-fcompare-debug failure" with "-O2 -ftracer" (2)

[jakub at gcc dot gnu dot org]

------- Comment #3 from jakub at gcc dot gnu dot org  2010-02-15 17:06 -------
The problem here is missing INSN location on insn generated by insert_restore
with -g (without -g it has one).
Before IRA we have:
(note 26 25 27 5 [bb 5] NOTE_INSN_BASIC_BLOCK)

(call_insn 27 26 28 5 pr42918.c:14 (call (mem:QI (symbol_ref:DI ("fv") [flags
0x41]  <function_decl 0x7feab75d6b00 fv>) [0 S1 A8])
        (const_int 0 [0x0])) 638 {*call_0} (nil)
    (nil))
(note 28 27 30 5 ("lab") NOTE_INSN_DELETED_LABEL 3)
(debug_insn 30 28 34 5 (var_location:SI i (reg/v:SI 59 [ i ])) -1 (nil))
at the end of a basic block (obviously with -g0 the debug_insn is missing).
Now save_call_clobbered_regs restores all still saved regs at the end of a
basic block, when the bb doesn't end with a jump, it restores after the last
insn mentioned in reload_insn_chain for that bb, when it is a jump, then before
it.
As DEBUG_INSNs are included in reload_insn_chain, that is for -g after the
DEBUG_INSN (and as insert_restore inserts after that insn, the insn has no
location as DEBUG_INSN has no location either).  For -g0 that is after the call
insn, which has location and thus the restore insn gets the location of the
call.
Although emit_insn_after ignores DEBUG_INSNs, it doesn't ignore notes and there
is this deleted label note in between.
Changing save_call_clobbered_regs to restore all regs after the last non-debug
insn in a bb wouldn't work well, as the restore insn invalidates the hard regs
that could still hold something in the debug insn.
I guess we could remember the INSN_LOCATOR of the last non-debug insn in the
reload chain and use emit_insn_after_setloc in insert_restore (going to test it
now), but wonder whether the fact that the deleted label is now after the hard
reg restore insn in the -g0 case and before it in the -g case couldn't
introduce other -fcompare-debug differences on other testcases.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42918

[Bug debug/42918] [4.5 Regression] "-fcompare-debug failure" with "-O2 -ftracer" (2)

[jakub at gcc dot gnu dot org]

------- Comment #4 from jakub at gcc dot gnu dot org  2010-02-15 20:55 -------
Created an attachment (id=19882)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=19882&action=view)
gcc45-pr42918.patch

Patch I've bootstrapped/regtested on x86_64-linux and i686-linux.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42918

[Bug debug/42918] [4.5 Regression] "-fcompare-debug failure" with "-O2 -ftracer" (2)

[jakub at gcc dot gnu dot org]

------- Comment #5 from jakub at gcc dot gnu dot org  2010-02-17 08:55 -------
Subject: Bug 42918

Author: jakub
Date: Wed Feb 17 08:54:59 2010
New Revision: 156823

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=156823
Log:
        PR debug/42918
        * caller-save.c (save_call_clobbered_regs): If BB ends with
        a DEBUG_INSN, move any notes in between last real insn and the last
        DEBUG_INSN after the last DEBUG_INSN.

        * gcc.dg/pr42918.c: New test.

Added:
    trunk/gcc/testsuite/gcc.dg/pr42918.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/caller-save.c
    trunk/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42918

[Bug debug/42918] [4.5 Regression] "-fcompare-debug failure" with "-O2 -ftracer" (2)

[jakub at gcc dot gnu dot org]

------- Comment #6 from jakub at gcc dot gnu dot org  2010-02-17 08:59 -------
Fixed.


-- 

jakub at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42918