[Bug c/31642] New: -O2 -fno-guess-branch-probability -fno-tree-ch -fno-tree-dominator-opts -fno-tree-lrs -fno-tree-dce -fno-tree-vrp -funit-at-a-time -ftree-copy-prop -ftree-copyrename yields an infinite loop in SPEC benchmark 176.gcc

["kenneth dot hoste at elis dot ugent dot be" <gcc-bugzilla at gcc dot gnu dot org>]

Using -O2 -fno-guess-branch-probability -fno-tree-ch -fno-tree-dominator-opts
-fno-tree-lrs -fno-tree-dce -fno-tree-vrp -funit-at-a-time -ftree-copy-prop
-ftree-copyrename on the SPEC CPU2000 benchmark 176.gcc yields an infinite loop
(using the train input which usually runs for 2s runs for hours). 

This is confirmed on Fedora Core 4 / x86 (Intel Pentium 4), and also on an
linux/amd64 for which I have no details.

Removing any of the -fno-X flags seems to solve the issue, and adding
-ffloat-store doesn't change a thing, which suggests this is not floating-point
(convergence) related.


-- 
           Summary: -O2 -fno-guess-branch-probability -fno-tree-ch -fno-
                    tree-dominator-opts -fno-tree-lrs -fno-tree-dce -fno-
                    tree-vrp -funit-at-a-time -ftree-copy-prop -ftree-
                    copyrename yields an infinite loop in SPEC benchmark
                    176.gcc
           Product: gcc
           Version: 4.1.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: kenneth dot hoste at elis dot ugent dot be
  GCC host triplet: i686-Linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31642