[Bug tree-optimization/23286] missed fully redundant expression

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23286

--- Comment #39 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-02-20 
11:50:00 UTC ---
Apart from that libada bootstrap issue (reproduces with the stage1 compiler),
the testsuite is clean apart from vectorizer testcases which show that
do_hoist_insertion is hoisting stmts across loops


  for (i = 0; i < N; i++) {
    diff = 0;
    for (j = k; j < M; j+=4) {
      diff += in[j+i]*coeff[j];
    }
    out[i] = out[i] + diff;
  }

is turned into

  for (i = 0; i < N; i++) {
    diff = 0;
    tem = out[i];
    for (j = k; j < M; j+=4) {
      diff += in[j+i]*coeff[j];
    }
    out[i] = tem + diff;
  }

which confuses outer loop vectorization enough to make it fail for

FAIL: gcc.dg/vect/vect-outer-fir-big-array.c -flto scan-tree-dump-times vect
"OU
TER LOOP VECTORIZED" 2
FAIL: gcc.dg/vect/vect-outer-fir-lb-big-array.c -flto scan-tree-dump-times vect 
"OUTER LOOP VECTORIZED" 2
FAIL: gcc.dg/vect/vect-outer-fir-lb.c -flto scan-tree-dump-times vect "OUTER
LOO
P VECTORIZED" 2
FAIL: gcc.dg/vect/vect-outer-fir.c -flto scan-tree-dump-times vect "OUTER LOOP
V
ECTORIZED" 2