[Bug tree-optimization/50763] New: [4.7 Regression] ICE: verify_gimple failed: missing PHI def with -O2 -fno-tree-ccp -fno-tree-copy-prop -fno-tree-vrp

[zsojka at seznam dot cz]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50763

             Bug #: 50763
           Summary: [4.7 Regression] ICE: verify_gimple failed: missing
                    PHI def with -O2 -fno-tree-ccp -fno-tree-copy-prop
                    -fno-tree-vrp
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassig...@gcc.gnu.org
        ReportedBy: zso...@seznam.cz
                CC: vr...@gcc.gnu.org
              Host: x86_64-pc-linux-gnu
            Target: x86_64-pc-linux-gnu


Created attachment 25527
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25527
reduced testcase

Compiler output:
$ gcc -O2 -fno-tree-ccp -fno-tree-copy-prop -fno-tree-vrp testcase.c
testcase.c: In function 'f':
testcase.c:6:5: warning: incompatible implicit declaration of built-in function
'exp' [enabled by default]
testcase.c:3:6: error: missing PHI def
.MEM_9 = PHI <.MEM_4(D)(2), .MEM_5(5), (4)>

testcase.c:3:6: internal compiler error: verify_gimple failed
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.

Might be related to -ftree-tail-merge, as it doesn't crash with
-fno-tree-tail-merge.

Tested revisions:
r180072 - crash
r179959 - crash
r178498 - OK
4.6 r177922 - OK