[Bug fortran/40386] New: wrong code generation for SPEC CPU2000's 189.lucas with -O1 -fno-ira-share-spill-slots

[kenneth dot hoste at elis dot ugent dot be]

I'm observing a wrong code generation bug with the 189.lucas benchmark in SPEC
CPU2000.

When the Fortran benchmark is being compiled with -O1
-fno-ira-share-spill-slots, the benchmark outputs the following:

iteration=         2  000000000000000E
iteration=         3  00000000000000C2
iteration=         4  0000000000009302
iteration=         5  00000000546B4C02
iteration=         6  1BD696D9F03D3002
M75460003 Roundoff warning on iteration       7 maxerr =  0.499999970088
 FATAL ERROR...Halting execution.

When compiled with -O1, this is (part of) the output (which is correct, as
specified by the CPU2000 framework):

iteration=         2  000000000000000E
iteration=         3  00000000000000C2
iteration=         4  0000000000009302
iteration=         5  00000000546B4C02
iteration=         6  1BD696D9F03D3002
iteration=         7  8CC88407A9F4C002
iteration=         8  55599F9D37D30002
<snip>
iteration=       122  E9639F5835FD3C2C
  exponent     residue
  75460003  DDD9C8B13BCB64AE


I'm sorry I'm unable to provide a self-contained testcase for this, but I know
little about Fortran. I hope someone else can jump in and provide a testcase
for me.


-- 
           Summary: wrong code generation for SPEC CPU2000's 189.lucas with
                    -O1 -fno-ira-share-spill-slots
           Product: gcc
           Version: 4.4.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: kenneth dot hoste at elis dot ugent dot be
 GCC build triplet: linux, x86-64
  GCC host triplet: linux, x86-64
GCC target triplet: linux, x86-64


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40386