[Bug tree-optimization/53366] New: wrong code generation by tree vectorizer using AVX

[martin@mpa-garching.mpg.de]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53366

             Bug #: 53366
           Summary: wrong code generation by tree vectorizer using AVX
    Classification: Unclassified
           Product: gcc
           Version: 4.7.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: martin@mpa-garching.mpg.de


Created attachment 27410
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27410
Testcase demonstrating the problem

The attached code is the reduction of a numerical library. It should print
"2.816937e+08" if executed correctly.
Using the current head of the 4.7 branch and trunk, and compiling on an
Intel Core i3-2120 using

gcc testcase.c -std=c99 -g -O3 -march=native -fno-tree-vectorize

everything works as expected.
When omitting the "-fno-tree-vectorize", random results are printed, and a
different number is generated for every run.

The testcase is the result of several hours' reduction. Currently I don't have
time to reduce it further.