Re: Fix bugs introduced by switch-case profile propagation

[Easwaran Raman <eraman at google dot com>]

On Tue, Oct 23, 2012 at 3:03 AM, Jan Hubicka <hubicka@ucw.cz> wrote:
>> Ping.
>>
>>
>> On Wed, Oct 17, 2012 at 1:48 PM, Easwaran Raman <eraman@google.com> wrote:
>> > Hi,
>> >  This patch fixes bugs introduced by my previous patch to propagate
>> > profiles during switch expansion. Bootstrap and profiledbootstrap
>> > successful on x86_64. Confirmed that it fixes the crashes reported in
>> > PR middle-end/54957. OK for trunk?
>> >
>> > - Easwaran
>> >
>> > 2012-10-17   Easwaran Raman  <eraman@google.com>
>> >
>> >         PR target/54938
>> >         PR middle-end/54957
>> >         * optabs.c (emit_cmp_and_jump_insn_1): Add REG_BR_PROB note
>> >         only if it doesn't already exist.
>> >         * except.c (sjlj_emit_function_enter): Remove unused variable.
>> >         * stmt.c (get_outgoing_edge_probs): Return 0 if BB is NULL.
>
> Seems fine, but under what conditions you get NULL here?

When expand_sjlj_dispatch_table calls emit_case_dispatch_table,
stmt_bb is NULL.

- Easwaran

> Honza
>> >         (emit_case_dispatch_table): Handle the case where STMT_BB is
>> >         NULL.
>> >         (expand_sjlj_dispatch_table): Pass BB containing before_case
>> >         to emit_case_dispatch_table.
>> >
>> > Index: gcc/optabs.c
>> > ===================================================================
>> > --- gcc/optabs.c (revision 192488)
>> > +++ gcc/optabs.c (working copy)
>> > @@ -4268,11 +4268,9 @@ emit_cmp_and_jump_insn_1 (rtx test, enum machine_m
>> >        && profile_status != PROFILE_ABSENT
>> >        && insn
>> >        && JUMP_P (insn)
>> > -      && any_condjump_p (insn))
>> > -    {
>> > -      gcc_assert (!find_reg_note (insn, REG_BR_PROB, 0));
>> > -      add_reg_note (insn, REG_BR_PROB, GEN_INT (prob));
>> > -    }
>> > +      && any_condjump_p (insn)
>> > +      && !find_reg_note (insn, REG_BR_PROB, 0))
>> > +    add_reg_note (insn, REG_BR_PROB, GEN_INT (prob));
>> >  }
>> >
>> >  /* Generate code to compare X with Y so that the condition codes are
>> > Index: gcc/except.c
>> > ===================================================================
>> > --- gcc/except.c (revision 192488)
>> > +++ gcc/except.c (working copy)
>> > @@ -1153,7 +1153,7 @@ sjlj_emit_function_enter (rtx dispatch_label)
>> >    if (dispatch_label)
>> >      {
>> >  #ifdef DONT_USE_BUILTIN_SETJMP
>> > -      rtx x, last;
>> > +      rtx x;
>> >        x = emit_library_call_value (setjmp_libfunc, NULL_RTX, LCT_RETURNS_TWICE,
>> >     TYPE_MODE (integer_type_node), 1,
>> >     plus_constant (Pmode, XEXP (fc, 0),
>> > Index: gcc/stmt.c
>> > ===================================================================
>> > --- gcc/stmt.c (revision 192488)
>> > +++ gcc/stmt.c (working copy)
>> > @@ -1867,6 +1867,8 @@ get_outgoing_edge_probs (basic_block bb)
>> >    edge e;
>> >    edge_iterator ei;
>> >    int prob_sum = 0;
>> > +  if (!bb)
>> > +    return 0;
>> >    FOR_EACH_EDGE(e, ei, bb->succs)
>> >      prob_sum += e->probability;
>> >    return prob_sum;
>> > @@ -1916,8 +1918,8 @@ emit_case_dispatch_table (tree index_expr, tree in
>> >    rtx fallback_label = label_rtx (case_list->code_label);
>> >    rtx table_label = gen_label_rtx ();
>> >    bool has_gaps = false;
>> > -  edge default_edge = EDGE_SUCC(stmt_bb, 0);
>> > -  int default_prob = default_edge->probability;
>> > +  edge default_edge = stmt_bb ? EDGE_SUCC(stmt_bb, 0) : NULL;
>> > +  int default_prob = default_edge ? default_edge->probability : 0;
>> >    int base = get_outgoing_edge_probs (stmt_bb);
>> >    bool try_with_tablejump = false;
>> >
>> > @@ -1997,7 +1999,8 @@ emit_case_dispatch_table (tree index_expr, tree in
>> >        default_prob = 0;
>> >      }
>> >
>> > -  default_edge->probability = default_prob;
>> > +  if (default_edge)
>> > +    default_edge->probability = default_prob;
>> >
>> >    /* We have altered the probability of the default edge. So the probabilities
>> >       of all other edges need to be adjusted so that it sums up to
>> > @@ -2289,7 +2292,8 @@ expand_sjlj_dispatch_table (rtx dispatch_index,
>> >
>> >        emit_case_dispatch_table (index_expr, index_type,
>> >   case_list, default_label,
>> > - minval, maxval, range, NULL);
>> > + minval, maxval, range,
>> > +                                BLOCK_FOR_INSN (before_case));
>> >        emit_label (default_label);
>> >        free_alloc_pool (case_node_pool);
>> >      }