Better fix for the x86_64 -mcmodel=large ICEs (PR target/82145)

Message ID 20170913103224.GV1701@tucnak
State New
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Series
  • Better fix for the x86_64 -mcmodel=large ICEs (PR target/82145)
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Commit Message

Jakub Jelinek Sept. 13, 2017, 10:32 a.m.
Hi!

The testcase below (and others) still ICEs with my PR81766 fix.
If there is a cfg cleanup in between ix86_init_pic_reg (during RA)
and postreload, the label which my fix moved to the right spot is
turned into NOTE_INSN_DELETED_LABEL note and moved back where it
originally used to be emitted.

The bug is actually in generic code.
cselib.c has code to handle LABEL_REF properly during hashing, by not
hashing the instructions/notes that are operand thereof, but just the
label number.  Postreload though calls cselib_lookup directly on the
operands of an instruction, and it is very common in many backends to have
(label_ref (match_operand ...)) in many patterns, and thus cselib
doesn't use the LABEL_REF handling in that case.
To avoid crashing postreload.c has:
       /* cselib blows up on CODE_LABELs.  Trying to fix that doesn't seem
          right, so avoid the problem here.  Likewise if we have a constant
          and the insn pattern doesn't tell us the mode we need.  */
       if (LABEL_P (recog_data.operand[i])
           || (CONSTANT_P (recog_data.operand[i])
               && recog_data.operand_mode[i] == VOIDmode))
         continue;
- we won't look up anything useful for those operands anyway.
The problem is that a valid LABEL_REF operand doesn't have to be only
a CODE_LABEL, it can be a NOTE with NOTE_INSN_DELETED_LABEL if all we need
is the label's address and nothing else.

So, the following patch handles NOTE_INSN_DELETED_LABEL like CODE_LABEL
in postreload.c.

Once that is done, my earlier PR81766 fix can be effectively reverted
and instead the CODE_LABEL can be immediately turned into
NOTE_INSN_DELETED_LABEL, something that a cfgcleanup would do.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2017-09-13  Jakub Jelinek  <jakub@redhat.com>

	PR target/82145
	* postreload.c (reload_cse_simplify_operands): Skip
	NOTE_INSN_DELETED_LABEL similarly to skipping CODE_LABEL.
	* config/i386/i386.c (ix86_init_large_pic_reg): Revert 2017-09-01
	changes.  Turn CODE_LABEL into NOTE_INSN_DELETED_LABEL immediately.
	(ix86_init_pic_reg): Revert 2017-09-01 changes.

	* gcc.target/i386/pr82145.c: New test.


	Jakub

Comments

Richard Biener Sept. 13, 2017, 10:48 a.m. | #1
On Wed, 13 Sep 2017, Jakub Jelinek wrote:

> Hi!
> 
> The testcase below (and others) still ICEs with my PR81766 fix.
> If there is a cfg cleanup in between ix86_init_pic_reg (during RA)
> and postreload, the label which my fix moved to the right spot is
> turned into NOTE_INSN_DELETED_LABEL note and moved back where it
> originally used to be emitted.
> 
> The bug is actually in generic code.
> cselib.c has code to handle LABEL_REF properly during hashing, by not
> hashing the instructions/notes that are operand thereof, but just the
> label number.  Postreload though calls cselib_lookup directly on the
> operands of an instruction, and it is very common in many backends to have
> (label_ref (match_operand ...)) in many patterns, and thus cselib
> doesn't use the LABEL_REF handling in that case.
> To avoid crashing postreload.c has:
>        /* cselib blows up on CODE_LABELs.  Trying to fix that doesn't seem
>           right, so avoid the problem here.  Likewise if we have a constant
>           and the insn pattern doesn't tell us the mode we need.  */
>        if (LABEL_P (recog_data.operand[i])
>            || (CONSTANT_P (recog_data.operand[i])
>                && recog_data.operand_mode[i] == VOIDmode))
>          continue;
> - we won't look up anything useful for those operands anyway.
> The problem is that a valid LABEL_REF operand doesn't have to be only
> a CODE_LABEL, it can be a NOTE with NOTE_INSN_DELETED_LABEL if all we need
> is the label's address and nothing else.
> 
> So, the following patch handles NOTE_INSN_DELETED_LABEL like CODE_LABEL
> in postreload.c.
> 
> Once that is done, my earlier PR81766 fix can be effectively reverted
> and instead the CODE_LABEL can be immediately turned into
> NOTE_INSN_DELETED_LABEL, something that a cfgcleanup would do.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

The postreload change is ok.

Thanks,
Richard.

> 2017-09-13  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR target/82145
> 	* postreload.c (reload_cse_simplify_operands): Skip
> 	NOTE_INSN_DELETED_LABEL similarly to skipping CODE_LABEL.
> 	* config/i386/i386.c (ix86_init_large_pic_reg): Revert 2017-09-01
> 	changes.  Turn CODE_LABEL into NOTE_INSN_DELETED_LABEL immediately.
> 	(ix86_init_pic_reg): Revert 2017-09-01 changes.
> 
> 	* gcc.target/i386/pr82145.c: New test.
> 
> --- gcc/config/i386/i386.c.jj	2017-09-08 09:13:59.000000000 +0200
> +++ gcc/config/i386/i386.c	2017-09-11 14:48:50.532094255 +0200
> @@ -8885,7 +8885,7 @@ ix86_use_pseudo_pic_reg (void)
>  
>  /* Initialize large model PIC register.  */
>  
> -static rtx_code_label *
> +static void
>  ix86_init_large_pic_reg (unsigned int tmp_regno)
>  {
>    rtx_code_label *label;
> @@ -8902,7 +8902,10 @@ ix86_init_large_pic_reg (unsigned int tm
>    emit_insn (gen_set_got_offset_rex64 (tmp_reg, label));
>    emit_insn (ix86_gen_add3 (pic_offset_table_rtx,
>  			    pic_offset_table_rtx, tmp_reg));
> -  return label;
> +  const char *name = LABEL_NAME (label);
> +  PUT_CODE (label, NOTE);
> +  NOTE_KIND (label) = NOTE_INSN_DELETED_LABEL;
> +  NOTE_DELETED_LABEL_NAME (label) = name;
>  }
>  
>  /* Create and initialize PIC register if required.  */
> @@ -8911,7 +8914,6 @@ ix86_init_pic_reg (void)
>  {
>    edge entry_edge;
>    rtx_insn *seq;
> -  rtx_code_label *label = NULL;
>  
>    if (!ix86_use_pseudo_pic_reg ())
>      return;
> @@ -8921,7 +8923,7 @@ ix86_init_pic_reg (void)
>    if (TARGET_64BIT)
>      {
>        if (ix86_cmodel == CM_LARGE_PIC)
> -	label = ix86_init_large_pic_reg (R11_REG);
> +	ix86_init_large_pic_reg (R11_REG);
>        else
>  	emit_insn (gen_set_got_rex64 (pic_offset_table_rtx));
>      }
> @@ -8945,22 +8947,6 @@ ix86_init_pic_reg (void)
>    entry_edge = single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun));
>    insert_insn_on_edge (seq, entry_edge);
>    commit_one_edge_insertion (entry_edge);
> -
> -  if (label)
> -    {
> -      basic_block bb = BLOCK_FOR_INSN (label);
> -      rtx_insn *bb_note = PREV_INSN (label);
> -      /* If the note preceding the label starts a basic block, and the
> -	 label is a member of the same basic block, interchange the two.  */
> -      if (bb_note != NULL_RTX
> -	  && NOTE_INSN_BASIC_BLOCK_P (bb_note)
> -	  && bb != NULL
> -	  && bb == BLOCK_FOR_INSN (bb_note))
> -	{
> -	  reorder_insns_nobb (bb_note, bb_note, label);
> -	  BB_HEAD (bb) = label;
> -	}
> -    }
>  }
>  
>  /* Initialize a variable CUM of type CUMULATIVE_ARGS
> --- gcc/postreload.c.jj	2017-09-08 09:13:54.000000000 +0200
> +++ gcc/postreload.c	2017-09-11 14:49:04.977945563 +0200
> @@ -409,9 +409,12 @@ reload_cse_simplify_operands (rtx_insn *
>        CLEAR_HARD_REG_SET (equiv_regs[i]);
>  
>        /* cselib blows up on CODE_LABELs.  Trying to fix that doesn't seem
> -	 right, so avoid the problem here.  Likewise if we have a constant
> -         and the insn pattern doesn't tell us the mode we need.  */
> +	 right, so avoid the problem here.  Similarly NOTE_INSN_DELETED_LABEL.
> +	 Likewise if we have a constant and the insn pattern doesn't tell us
> +	 the mode we need.  */
>        if (LABEL_P (recog_data.operand[i])
> +	  || (NOTE_P (recog_data.operand[i])
> +	      && NOTE_KIND (recog_data.operand[i]) == NOTE_INSN_DELETED_LABEL)
>  	  || (CONSTANT_P (recog_data.operand[i])
>  	      && recog_data.operand_mode[i] == VOIDmode))
>  	continue;
> --- gcc/testsuite/gcc.target/i386/pr82145.c.jj	2017-09-11 14:46:08.612760951 +0200
> +++ gcc/testsuite/gcc.target/i386/pr82145.c	2017-09-11 14:47:22.090004622 +0200
> @@ -0,0 +1,12 @@
> +/* PR target/82145 */
> +/* { dg-do compile { target { pie && lp64 } } } */
> +/* { dg-options "-O2 -fpie -mcmodel=large -march=haswell" } */
> +
> +int l;
> +
> +int
> +main ()
> +{
> +  l++;
> +  return 0;
> +}
> 
> 	Jakub
> 
>
Uros Bizjak Sept. 17, 2017, 3:47 p.m. | #2
On Wed, Sep 13, 2017 at 12:48 PM, Richard Biener <rguenther@suse.de> wrote:
> On Wed, 13 Sep 2017, Jakub Jelinek wrote:
>
>> Hi!
>>
>> The testcase below (and others) still ICEs with my PR81766 fix.
>> If there is a cfg cleanup in between ix86_init_pic_reg (during RA)
>> and postreload, the label which my fix moved to the right spot is
>> turned into NOTE_INSN_DELETED_LABEL note and moved back where it
>> originally used to be emitted.
>>
>> The bug is actually in generic code.
>> cselib.c has code to handle LABEL_REF properly during hashing, by not
>> hashing the instructions/notes that are operand thereof, but just the
>> label number.  Postreload though calls cselib_lookup directly on the
>> operands of an instruction, and it is very common in many backends to have
>> (label_ref (match_operand ...)) in many patterns, and thus cselib
>> doesn't use the LABEL_REF handling in that case.
>> To avoid crashing postreload.c has:
>>        /* cselib blows up on CODE_LABELs.  Trying to fix that doesn't seem
>>           right, so avoid the problem here.  Likewise if we have a constant
>>           and the insn pattern doesn't tell us the mode we need.  */
>>        if (LABEL_P (recog_data.operand[i])
>>            || (CONSTANT_P (recog_data.operand[i])
>>                && recog_data.operand_mode[i] == VOIDmode))
>>          continue;
>> - we won't look up anything useful for those operands anyway.
>> The problem is that a valid LABEL_REF operand doesn't have to be only
>> a CODE_LABEL, it can be a NOTE with NOTE_INSN_DELETED_LABEL if all we need
>> is the label's address and nothing else.
>>
>> So, the following patch handles NOTE_INSN_DELETED_LABEL like CODE_LABEL
>> in postreload.c.
>>
>> Once that is done, my earlier PR81766 fix can be effectively reverted
>> and instead the CODE_LABEL can be immediately turned into
>> NOTE_INSN_DELETED_LABEL, something that a cfgcleanup would do.
>>
>> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
>
> The postreload change is ok.

The revert is OK even without approval.

Uros.

> Thanks,
> Richard.
>
>> 2017-09-13  Jakub Jelinek  <jakub@redhat.com>
>>
>>       PR target/82145
>>       * postreload.c (reload_cse_simplify_operands): Skip
>>       NOTE_INSN_DELETED_LABEL similarly to skipping CODE_LABEL.
>>       * config/i386/i386.c (ix86_init_large_pic_reg): Revert 2017-09-01
>>       changes.  Turn CODE_LABEL into NOTE_INSN_DELETED_LABEL immediately.
>>       (ix86_init_pic_reg): Revert 2017-09-01 changes.
>>
>>       * gcc.target/i386/pr82145.c: New test.
>>
>> --- gcc/config/i386/i386.c.jj 2017-09-08 09:13:59.000000000 +0200
>> +++ gcc/config/i386/i386.c    2017-09-11 14:48:50.532094255 +0200
>> @@ -8885,7 +8885,7 @@ ix86_use_pseudo_pic_reg (void)
>>
>>  /* Initialize large model PIC register.  */
>>
>> -static rtx_code_label *
>> +static void
>>  ix86_init_large_pic_reg (unsigned int tmp_regno)
>>  {
>>    rtx_code_label *label;
>> @@ -8902,7 +8902,10 @@ ix86_init_large_pic_reg (unsigned int tm
>>    emit_insn (gen_set_got_offset_rex64 (tmp_reg, label));
>>    emit_insn (ix86_gen_add3 (pic_offset_table_rtx,
>>                           pic_offset_table_rtx, tmp_reg));
>> -  return label;
>> +  const char *name = LABEL_NAME (label);
>> +  PUT_CODE (label, NOTE);
>> +  NOTE_KIND (label) = NOTE_INSN_DELETED_LABEL;
>> +  NOTE_DELETED_LABEL_NAME (label) = name;
>>  }
>>
>>  /* Create and initialize PIC register if required.  */
>> @@ -8911,7 +8914,6 @@ ix86_init_pic_reg (void)
>>  {
>>    edge entry_edge;
>>    rtx_insn *seq;
>> -  rtx_code_label *label = NULL;
>>
>>    if (!ix86_use_pseudo_pic_reg ())
>>      return;
>> @@ -8921,7 +8923,7 @@ ix86_init_pic_reg (void)
>>    if (TARGET_64BIT)
>>      {
>>        if (ix86_cmodel == CM_LARGE_PIC)
>> -     label = ix86_init_large_pic_reg (R11_REG);
>> +     ix86_init_large_pic_reg (R11_REG);
>>        else
>>       emit_insn (gen_set_got_rex64 (pic_offset_table_rtx));
>>      }
>> @@ -8945,22 +8947,6 @@ ix86_init_pic_reg (void)
>>    entry_edge = single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun));
>>    insert_insn_on_edge (seq, entry_edge);
>>    commit_one_edge_insertion (entry_edge);
>> -
>> -  if (label)
>> -    {
>> -      basic_block bb = BLOCK_FOR_INSN (label);
>> -      rtx_insn *bb_note = PREV_INSN (label);
>> -      /* If the note preceding the label starts a basic block, and the
>> -      label is a member of the same basic block, interchange the two.  */
>> -      if (bb_note != NULL_RTX
>> -       && NOTE_INSN_BASIC_BLOCK_P (bb_note)
>> -       && bb != NULL
>> -       && bb == BLOCK_FOR_INSN (bb_note))
>> -     {
>> -       reorder_insns_nobb (bb_note, bb_note, label);
>> -       BB_HEAD (bb) = label;
>> -     }
>> -    }
>>  }
>>
>>  /* Initialize a variable CUM of type CUMULATIVE_ARGS
>> --- gcc/postreload.c.jj       2017-09-08 09:13:54.000000000 +0200
>> +++ gcc/postreload.c  2017-09-11 14:49:04.977945563 +0200
>> @@ -409,9 +409,12 @@ reload_cse_simplify_operands (rtx_insn *
>>        CLEAR_HARD_REG_SET (equiv_regs[i]);
>>
>>        /* cselib blows up on CODE_LABELs.  Trying to fix that doesn't seem
>> -      right, so avoid the problem here.  Likewise if we have a constant
>> -         and the insn pattern doesn't tell us the mode we need.  */
>> +      right, so avoid the problem here.  Similarly NOTE_INSN_DELETED_LABEL.
>> +      Likewise if we have a constant and the insn pattern doesn't tell us
>> +      the mode we need.  */
>>        if (LABEL_P (recog_data.operand[i])
>> +       || (NOTE_P (recog_data.operand[i])
>> +           && NOTE_KIND (recog_data.operand[i]) == NOTE_INSN_DELETED_LABEL)
>>         || (CONSTANT_P (recog_data.operand[i])
>>             && recog_data.operand_mode[i] == VOIDmode))
>>       continue;
>> --- gcc/testsuite/gcc.target/i386/pr82145.c.jj        2017-09-11 14:46:08.612760951 +0200
>> +++ gcc/testsuite/gcc.target/i386/pr82145.c   2017-09-11 14:47:22.090004622 +0200
>> @@ -0,0 +1,12 @@
>> +/* PR target/82145 */
>> +/* { dg-do compile { target { pie && lp64 } } } */
>> +/* { dg-options "-O2 -fpie -mcmodel=large -march=haswell" } */
>> +
>> +int l;
>> +
>> +int
>> +main ()
>> +{
>> +  l++;
>> +  return 0;
>> +}
>>
>>       Jakub
>>
>>
>
> --
> Richard Biener <rguenther@suse.de>
> SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nuernberg)
Jakub Jelinek Sept. 17, 2017, 5:27 p.m. | #3
On Sun, Sep 17, 2017 at 05:47:11PM +0200, Uros Bizjak wrote:
> > The postreload change is ok.
> 
> The revert is OK even without approval.

Well, it isn't a pure reversion, it is reversion plus addition of
  const char *name = LABEL_NAME (label);
  PUT_CODE (label, NOTE);
  NOTE_KIND (label) = NOTE_INSN_DELETED_LABEL;
  NOTE_DELETED_LABEL_NAME (label) = name;
to the end of ix86_init_large_pic_reg.

> >> 2017-09-13  Jakub Jelinek  <jakub@redhat.com>
> >>
> >>       PR target/82145
> >>       * postreload.c (reload_cse_simplify_operands): Skip
> >>       NOTE_INSN_DELETED_LABEL similarly to skipping CODE_LABEL.
> >>       * config/i386/i386.c (ix86_init_large_pic_reg): Revert 2017-09-01
> >>       changes.  Turn CODE_LABEL into NOTE_INSN_DELETED_LABEL immediately.
> >>       (ix86_init_pic_reg): Revert 2017-09-01 changes.
> >>
> >>       * gcc.target/i386/pr82145.c: New test.

	Jakub
Uros Bizjak Sept. 18, 2017, 9:22 a.m. | #4
On Sun, Sep 17, 2017 at 7:27 PM, Jakub Jelinek <jakub@redhat.com> wrote:
> On Sun, Sep 17, 2017 at 05:47:11PM +0200, Uros Bizjak wrote:
>> > The postreload change is ok.
>>
>> The revert is OK even without approval.

I see.

The patch is also OK.

Thanks,
Uros.

> Well, it isn't a pure reversion, it is reversion plus addition of
>   const char *name = LABEL_NAME (label);
>   PUT_CODE (label, NOTE);
>   NOTE_KIND (label) = NOTE_INSN_DELETED_LABEL;
>   NOTE_DELETED_LABEL_NAME (label) = name;
> to the end of ix86_init_large_pic_reg.
>
>> >> 2017-09-13  Jakub Jelinek  <jakub@redhat.com>
>> >>
>> >>       PR target/82145
>> >>       * postreload.c (reload_cse_simplify_operands): Skip
>> >>       NOTE_INSN_DELETED_LABEL similarly to skipping CODE_LABEL.
>> >>       * config/i386/i386.c (ix86_init_large_pic_reg): Revert 2017-09-01
>> >>       changes.  Turn CODE_LABEL into NOTE_INSN_DELETED_LABEL immediately.
>> >>       (ix86_init_pic_reg): Revert 2017-09-01 changes.
>> >>
>> >>       * gcc.target/i386/pr82145.c: New test.
>
>         Jakub

Patch

--- gcc/config/i386/i386.c.jj	2017-09-08 09:13:59.000000000 +0200
+++ gcc/config/i386/i386.c	2017-09-11 14:48:50.532094255 +0200
@@ -8885,7 +8885,7 @@  ix86_use_pseudo_pic_reg (void)
 
 /* Initialize large model PIC register.  */
 
-static rtx_code_label *
+static void
 ix86_init_large_pic_reg (unsigned int tmp_regno)
 {
   rtx_code_label *label;
@@ -8902,7 +8902,10 @@  ix86_init_large_pic_reg (unsigned int tm
   emit_insn (gen_set_got_offset_rex64 (tmp_reg, label));
   emit_insn (ix86_gen_add3 (pic_offset_table_rtx,
 			    pic_offset_table_rtx, tmp_reg));
-  return label;
+  const char *name = LABEL_NAME (label);
+  PUT_CODE (label, NOTE);
+  NOTE_KIND (label) = NOTE_INSN_DELETED_LABEL;
+  NOTE_DELETED_LABEL_NAME (label) = name;
 }
 
 /* Create and initialize PIC register if required.  */
@@ -8911,7 +8914,6 @@  ix86_init_pic_reg (void)
 {
   edge entry_edge;
   rtx_insn *seq;
-  rtx_code_label *label = NULL;
 
   if (!ix86_use_pseudo_pic_reg ())
     return;
@@ -8921,7 +8923,7 @@  ix86_init_pic_reg (void)
   if (TARGET_64BIT)
     {
       if (ix86_cmodel == CM_LARGE_PIC)
-	label = ix86_init_large_pic_reg (R11_REG);
+	ix86_init_large_pic_reg (R11_REG);
       else
 	emit_insn (gen_set_got_rex64 (pic_offset_table_rtx));
     }
@@ -8945,22 +8947,6 @@  ix86_init_pic_reg (void)
   entry_edge = single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun));
   insert_insn_on_edge (seq, entry_edge);
   commit_one_edge_insertion (entry_edge);
-
-  if (label)
-    {
-      basic_block bb = BLOCK_FOR_INSN (label);
-      rtx_insn *bb_note = PREV_INSN (label);
-      /* If the note preceding the label starts a basic block, and the
-	 label is a member of the same basic block, interchange the two.  */
-      if (bb_note != NULL_RTX
-	  && NOTE_INSN_BASIC_BLOCK_P (bb_note)
-	  && bb != NULL
-	  && bb == BLOCK_FOR_INSN (bb_note))
-	{
-	  reorder_insns_nobb (bb_note, bb_note, label);
-	  BB_HEAD (bb) = label;
-	}
-    }
 }
 
 /* Initialize a variable CUM of type CUMULATIVE_ARGS
--- gcc/postreload.c.jj	2017-09-08 09:13:54.000000000 +0200
+++ gcc/postreload.c	2017-09-11 14:49:04.977945563 +0200
@@ -409,9 +409,12 @@  reload_cse_simplify_operands (rtx_insn *
       CLEAR_HARD_REG_SET (equiv_regs[i]);
 
       /* cselib blows up on CODE_LABELs.  Trying to fix that doesn't seem
-	 right, so avoid the problem here.  Likewise if we have a constant
-         and the insn pattern doesn't tell us the mode we need.  */
+	 right, so avoid the problem here.  Similarly NOTE_INSN_DELETED_LABEL.
+	 Likewise if we have a constant and the insn pattern doesn't tell us
+	 the mode we need.  */
       if (LABEL_P (recog_data.operand[i])
+	  || (NOTE_P (recog_data.operand[i])
+	      && NOTE_KIND (recog_data.operand[i]) == NOTE_INSN_DELETED_LABEL)
 	  || (CONSTANT_P (recog_data.operand[i])
 	      && recog_data.operand_mode[i] == VOIDmode))
 	continue;
--- gcc/testsuite/gcc.target/i386/pr82145.c.jj	2017-09-11 14:46:08.612760951 +0200
+++ gcc/testsuite/gcc.target/i386/pr82145.c	2017-09-11 14:47:22.090004622 +0200
@@ -0,0 +1,12 @@ 
+/* PR target/82145 */
+/* { dg-do compile { target { pie && lp64 } } } */
+/* { dg-options "-O2 -fpie -mcmodel=large -march=haswell" } */
+
+int l;
+
+int
+main ()
+{
+  l++;
+  return 0;
+}