[Bug tree-optimization/20543] New: [4.1 Regression] Bootstrap failure at -Os

[rearnsha at gcc dot gnu dot org]

Bootstrapping with BOOT_CFLAGS="-Os -g" fails when the stage2 cc1 is used to
build  crtstuff.o.  The segmentation fault occurs in find_uses_to_rename_use but
the error really seems to be in its caller find_uses_to_rename_bb
(tree-ssa-loop-manip.c).  Looking at the tree dumps we have in t49.loopinit

<L8>:;
  stmt_35 = bsi_stmt (bsi);
  get_stmt_operands (stmt_35);
  var_38 = op_iter_init_tree (&iter, stmt_35, 13);
  goto <bb 9> (<L10>);

<L9>:;
  var_45 = op_iter_next_tree (&iter);

<L10>:;
  D.17355_41 = iter.done;
  D.17353_42 = (int) D.17355_41;
  D.17347_44 = (unsigned char) D.17353_42;
  if (D.17347_44 == 0) goto <L9>; else goto <L12>;

but in t50.lim we have:

<L8>:;
  stmt_35 = bsi_stmt (bsi);
  get_stmt_operands (stmt_35);
  var_38 = op_iter_init_tree (&iter, stmt_35, 13);
  lsm_tmp.500_356 = iter.done;
  goto <bb 9> (<L10>);

<L9>:;
  var_45 = op_iter_next_tree (&iter);

<L10>:;
  D.17355_41 = lsm_tmp.500_356;
  D.17353_42 = (int) D.17355_41;
  D.17347_44 = (unsigned char) D.17353_42;
  if (D.17347_44 == 0) goto <L9>; else goto <L18>;

<L18>:;
  iter.done = lsm_tmp.500_356;

note that the use of iter.done has been hoisted out of the loop even though the
call of op_iter_next_tree passes the address of iter.

-- 
           Summary: [4.1 Regression] Bootstrap failure at -Os
           Product: gcc
           Version: 4.1.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P2
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: rearnsha at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org
  GCC host triplet: i386-unknown-netbsdelf arm-unknown-netbsdelf
GCC target triplet: i386-unknown-netbsdelf arm-unknown-netbsdelf


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20543