[Bug c/12626] New: [3.4 regression] Infinite loop compiling gcc.c-torture/compile/950512-1.c at -O1 and above

["danglin at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12626

           Summary: [3.4 regression] Infinite loop compiling gcc.c-
                    torture/compile/950512-1.c at -O1 and above
           Product: gcc
           Version: 3.4
            Status: UNCONFIRMED
          Severity: critical
          Priority: P2
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: danglin at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org,kenner at vlsi1 dot
                    ultra dot nyu dot edu
 GCC build triplet: hppa2.0w-hp-hpux11.11, hppa-unknown-linux-gnu
  GCC host triplet: hppa2.0w-hp-hpux11.11, hppa-unknown-linux-gnu
GCC target triplet: hppa2.0w-hp-hpux11.11, hppa-unknown-linux-gnu

Executing on host: /home/dave/gnu/gcc-3.4/objdir/gcc/xgcc -B/home/dave/gnu/gcc-3
.4/objdir/gcc/   -O1  -w -c  -o 950512-1.o /home/dave/gnu/gcc-3.4/gcc/gcc/testsu
ite/gcc.c-torture/compile/950512-1.c    (timeout = 300)
WARNING: program timed out.
compiler exited with status 1

The failure was introduced by the following patch:

2003-10-10  Richard Kenner  <kenner@vlsi1.ultra.nyu.edu>

        * combine.c (distribute_links): Properly test for REG being set.

A preliminary analysis seems to indicate that the actual problem
is a REG_RETVAL note linked back to itself.  This causes the loop in
distribute_links.  There were some changes to the note handling earlier
in the month but I don't know if this is the cause of the problem.