[Bug middle-end/40386] 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]

------- Comment #2 from kenneth dot hoste at elis dot ugent dot be  2009-06-09 13:35 -------
I did some more experiments, and have some more details to share.

It seems the problem with lucas only occurs with the SVN head of the 4.4 branch
I'm working on (r148268), and not with the 4.4.0 release.

However, a similar problem is occuring with the 172.mgrid benchmark, and this
_is_ occuring both with the 4.4.0 release and with revision 148268 of the 4.4
branch.

Again, -O1 -fno-ira-share-spill-slots leads to a binary not producing correct
output (but there's not noticeable crash of the benchmark this time). Using -O1
yields no problems though.

The SPEC framework reports the below as a diff between the expected and
observed output for mgrid, and considers the difference to be serious enough to
report the run to be invalid.

0019:      0.103090E-02
          -0.907513E-03
                      ^
0020:      0.103090E-02
          -0.907513E-03
                      ^
0021:      0.184495E-02
           0.261074E-02
                      ^
0022:      0.184495E-02
           0.261074E-02
                      ^
0023:      0.366257E-03
          -0.677032E-04
                      ^
0024:      0.366257E-03
          -0.677032E-04
                      ^
0025:      0.436098E-03
           0.179609E-03
                      ^
0026:      0.436098E-03
           0.179609E-03
                      ^
0027:      0.442029E-03
           0.212079E-03
                      ^
0028:      0.442029E-03
           0.212079E-03
                      ^
0029:      0.442962E-03
           0.217171E-03
                      ^


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