[Bug target/50721] [4.6/4.7 Regression] Segfault of -O0 compiled program on x86_64 related to register allocator

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

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50721

Tobias Burnus <burnus at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Target|                            |x86_64-unknown-linux-gnu
                 CC|                            |bernds at gcc dot gnu.org
          Component|fortran                     |target
   Target Milestone|---                         |4.6.2
            Summary|[4.6/4.7 Regression]        |[4.6/4.7 Regression]
                   |gfortran miscompiles FGSL   |Segfault of -O0 compiled
                   |                            |program on x86_64 related
                   |                            |to register allocator

--- Comment #7 from Tobias Burnus <burnus at gcc dot gnu.org> 2011-10-13 23:56:40 UTC ---
Another observation: Works with -m32, fails with -m64 (on
x86_64-unknown-linux-gnu)

Regression hunting using 4.6.0 20100429 (experimental):

Works:  Rev. 158910
Fails:  Rev. 158911

That's the following commit:

Author: bernds
Date: Thu Apr 29 21:37:01 2010
New Revision: 158911

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=158911
Log:
    PR target/42895
    * doc/tm.texi (ADJUST_REG_ALLOC_ORDER): Renamed from
    ORDER_REGS_FOR_LOCAL_ALLOC.  All instances of this macro changed.
    (HONOR_REG_ALLOC_ORDER): Describe new macro.
    * ira.c (setup_alloc_regs): Use ADJUST_REG_ALLOC_ORDER if defined.
    * ira-color.c (assign_hard_reg): Take prologue/epilogue costs into
    account only if HONOR_REG_ALLOC_ORDER is not defined.
    * config/arm/arm.h (HONOR_REG_ALLOC_ORDER): Define.
    * system.h (ORDER_REGS_FOR_LOCAL_ALLOC): Poison.