[Bug tree-optimization/33299] [4.3 Regression] miscompilation with gfortran -O2 -ffast-math -ftree-vectorize

[dorit at gcc dot gnu dot org]

------- Comment #3 from dorit at gcc dot gnu dot org  2007-09-04 19:11 -------
I'm testing this patch:

Index: tree-vect-transform.c
===================================================================
*** tree-vect-transform.c       (revision 128037)
--- tree-vect-transform.c       (working copy)
*************** vect_create_epilog_for_reduction (tree v
*** 1964,1969 ****
--- 1964,1971 ----
    tree operation = GIMPLE_STMT_OPERAND (stmt, 1);
    bool nested_in_vect_loop = false;
    int op_type;
+   VEC(tree,heap) *phis = NULL;
+   int i;

    if (nested_in_vect_loop_p (loop, stmt))
      {
*************** vect_finalize_reduction:
*** 2260,2270 ****
        epilog_stmt = build_gimple_modify_stmt (new_dest, expr);
        new_temp = make_ssa_name (new_dest, epilog_stmt);
        GIMPLE_STMT_OPERAND (epilog_stmt, 0) = new_temp;
- #if 0
-       bsi_insert_after (&exit_bsi, epilog_stmt, BSI_NEW_STMT);
- #else
        bsi_insert_before (&exit_bsi, epilog_stmt, BSI_SAME_STMT);
- #endif
      }


--- 2262,2268 ----
*************** vect_finalize_reduction:
*** 2274,2318 ****
       Find the loop-closed-use at the loop exit of the original scalar result.
       (The reduction result is expected to have two immediate uses - one at
the
       latch block, and one at the loop exit).  */
!   exit_phi = NULL;
    FOR_EACH_IMM_USE_FAST (use_p, imm_iter, scalar_dest)
      {
        if (!flow_bb_inside_loop_p (loop, bb_for_stmt (USE_STMT (use_p))))
        {
          exit_phi = USE_STMT (use_p);
!         break;
        }
      }
    /* We expect to have found an exit_phi because of loop-closed-ssa form.  */
!   gcc_assert (exit_phi);

!   if (nested_in_vect_loop)
      {
!       stmt_vec_info stmt_vinfo = vinfo_for_stmt (exit_phi);

!       /* FORNOW. Currently not supporting the case that an inner-loop
reduction
!        is not used in the outer-loop (but only outside the outer-loop).  */
!       gcc_assert (STMT_VINFO_RELEVANT_P (stmt_vinfo) 
!                 && !STMT_VINFO_LIVE_P (stmt_vinfo));
! 
!       epilog_stmt = adjustment_def ? epilog_stmt :  new_phi;
!       STMT_VINFO_VEC_STMT (stmt_vinfo) = epilog_stmt;
!       set_stmt_info (get_stmt_ann (epilog_stmt),
!                      new_stmt_vec_info (epilog_stmt, loop_vinfo));

!       if (vect_print_dump_info (REPORT_DETAILS))
!         {
!           fprintf (vect_dump, "vector of partial results after inner-loop:");
!           print_generic_expr (vect_dump, epilog_stmt, TDF_SLIM);
!         }
!       return;
      }
- 
-   /* Replace the uses:  */
-   orig_name = PHI_RESULT (exit_phi);
-   FOR_EACH_IMM_USE_STMT (use_stmt, imm_iter, orig_name)
-     FOR_EACH_IMM_USE_ON_STMT (use_p, imm_iter)
-       SET_USE (use_p, new_temp);
  } 


--- 2272,2313 ----
       Find the loop-closed-use at the loop exit of the original scalar result.
       (The reduction result is expected to have two immediate uses - one at
the 
       latch block, and one at the loop exit).  */
!   phis = VEC_alloc (tree, heap, 10);
    FOR_EACH_IMM_USE_FAST (use_p, imm_iter, scalar_dest)
      {
        if (!flow_bb_inside_loop_p (loop, bb_for_stmt (USE_STMT (use_p))))
        {
          exit_phi = USE_STMT (use_p);
!         VEC_quick_push (tree, phis, exit_phi);
        }
      }
    /* We expect to have found an exit_phi because of loop-closed-ssa form.  */
!   gcc_assert (!VEC_empty (tree, phis));

!   for (i = 0; VEC_iterate (tree, phis, i, exit_phi); i++)
      {
!       if (nested_in_vect_loop)
!       {
!         stmt_vec_info stmt_vinfo = vinfo_for_stmt (exit_phi);

!         /* FORNOW. Currently not supporting the case that an inner-loop
reduction
!            is not used in the outer-loop (but only outside the outer-loop). 
*/
!         gcc_assert (STMT_VINFO_RELEVANT_P (stmt_vinfo) 
!                     && !STMT_VINFO_LIVE_P (stmt_vinfo));
!
!         epilog_stmt = adjustment_def ? epilog_stmt :  new_phi;
!         STMT_VINFO_VEC_STMT (stmt_vinfo) = epilog_stmt;
!         set_stmt_info (get_stmt_ann (epilog_stmt),
!         new_stmt_vec_info (epilog_stmt, loop_vinfo));
!         continue;
!       }

!       /* Replace the uses:  */
!       orig_name = PHI_RESULT (exit_phi);
!       FOR_EACH_IMM_USE_STMT (use_stmt, imm_iter, orig_name)
!       FOR_EACH_IMM_USE_ON_STMT (use_p, imm_iter)
!         SET_USE (use_p, new_temp);
      }
  } 


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33299