On 21/11/11 17:13, Michael Matz wrote:
> Hi,
>
> On Sat, 19 Nov 2011, Tom de Vries wrote:
>
>> On 11/18/2011 10:29 PM, Eric Botcazou wrote:
>>>> For the test-case of PR50764, a dead label is introduced by
>>>> fixup_reorder_chain in cfg_layout_finalize, called from
>>>> pass_reorder_blocks.
>>>
>>> I presume that there is no reasonable way of preventing fixup_reorder_chain
>>> from introducing it or of teaching fixup_reorder_chain to remove it?
>>>
>>
>> This (untested) patch also removes the dead label for the PR, and I
>> think it is safe. ...
>
> cfgrtl.c has already code to delete labels (delete_insn) when appropriate
> (can_delete_label_p). Perhaps that can be reused somehow.
>
>> Index: cfglayout.c
>> =================================================================== ---
>> cfglayout.c (revision 181377) +++ cfglayout.c (working copy) @@ -702,6
>> +702,21 @@ relink_block_chain (bool stay_in_cfglayo
>> }
>>
>>
>> +static bool
>> +forced_label_p (rtx label)
>> +{
>> + rtx insn, forced_label;
>> + for (insn = forced_labels; insn; insn = XEXP (insn, 1))
>> + {
>> + forced_label = XEXP (insn, 0);
>> + if (!LABEL_P (forced_label))
>> + continue;
>> + if (forced_label == label)
>> + return true;
>> + }
>> + return false;
>> +}
>
> That's in_expr_list_p().
>
>> @@ -857,6 +872,12 @@ fixup_reorder_chain (void)
>> (e_taken->src, e_taken->dest));
>> e_taken->flags |= EDGE_FALLTHRU;
>> update_br_prob_note (bb);
>> + if (LABEL_NUSES (ret_label) == 0
>
>> + && !LABEL_PRESERVE_P (ret_label)
>> + && LABEL_NAME (ret_label) == NULL
>> + && !forced_label_p (ret_label)
>
> And this is cfgrtl.c:can_delete_label_p.
Ok, using that in the new version.
> Note that you actually
> can remove labels also if they are !can_delete_label_p, if you use
> delete_insn (which you do). It will replace such undeletable labels by a
> DELETED_LABEL note.
>
I tried that as well but ran into these errors in rtl_verify_flow_info_1:
...
libquadmath/printf/cmp.c:56:1: error: NOTE_INSN_BASIC_BLOCK is missing for
block 6
libquadmath/printf/cmp.c:56:1: error: NOTE_INSN_BASIC_BLOCK 79 in middle of
basic block 6
libquadmath/printf/cmp.c:56:1: internal compiler error: verify_flow_info failed
a-direct.ads:460:9: error: NOTE_INSN_BASIC_BLOCK is missing for block 6
a-direct.ads:460:9: error: NOTE_INSN_BASIC_BLOCK 25 in middle of basic block 6
+===========================GNAT BUG DETECTED==============================+
| 4.7.0 20111123 (experimental) (x86_64-unknown-linux-gnu) GCC error: |
| verify_flow_info failed |
| Error detected around a-direct.ads:460:9 |
...
Eric,
This new patch was bootstrapped and reg-tested on x86_64.
this new patch or old patch (
http://gcc.gnu.org/ml/gcc-patches/2011-11/msg01953.html ) ok for next stage1?
Thanks,
- Tom
>
> Ciao,
> Michael.
2011-11-25 Tom de Vries <[email protected]>
* rtl.h (can_delete_label_p): Declare.
* cfgrtl.c (can_delete_label_p): Remove static.
* cfglayout.c (fixup_reorder_chain): Delete unused label if
can_delete_label_p.
* gcc.dg/superblock.c: New test.
Index: gcc/cfglayout.c
===================================================================
--- gcc/cfglayout.c (revision 181652)
+++ gcc/cfglayout.c (working copy)
@@ -857,6 +857,10 @@ fixup_reorder_chain (void)
(e_taken->src, e_taken->dest));
e_taken->flags |= EDGE_FALLTHRU;
update_br_prob_note (bb);
+ if (LABEL_NUSES (ret_label) == 0
+ && can_delete_label_p (ret_label)
+ && single_pred_p (e_taken->dest))
+ delete_insn (ret_label);
continue;
}
}
Index: gcc/rtl.h
===================================================================
--- gcc/rtl.h (revision 181652)
+++ gcc/rtl.h (working copy)
@@ -2482,6 +2482,9 @@ extern void dump_combine_total_stats (FI
/* In cfgcleanup.c */
extern void delete_dead_jumptables (void);
+/* In rtlcfg.c */
+int can_delete_label_p (const_rtx);
+
/* In sched-vis.c. */
extern void debug_bb_n_slim (int);
extern void debug_bb_slim (struct basic_block_def *);
Index: gcc/cfgrtl.c
===================================================================
--- gcc/cfgrtl.c (revision 181652)
+++ gcc/cfgrtl.c (working copy)
@@ -66,7 +66,6 @@ along with GCC; see the file COPYING3.
#include "df.h"
static int can_delete_note_p (const_rtx);
-static int can_delete_label_p (const_rtx);
static basic_block rtl_split_edge (edge);
static bool rtl_move_block_after (basic_block, basic_block);
static int rtl_verify_flow_info (void);
@@ -102,7 +101,7 @@ can_delete_note_p (const_rtx note)
/* True if a given label can be deleted. */
-static int
+int
can_delete_label_p (const_rtx label)
{
return (!LABEL_PRESERVE_P (label)
Index: gcc/testsuite/gcc.dg/superblock.c
===================================================================
--- /dev/null (new file)
+++ gcc/testsuite/gcc.dg/superblock.c (revision 0)
@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fno-asynchronous-unwind-tables -fsched2-use-superblocks -fdump-rtl-sched2 -fdump-rtl-bbro" } */
+
+typedef int aligned __attribute__ ((aligned (64)));
+extern void abort (void);
+
+int bar (void *p);
+
+void
+foo (void)
+{
+ char *p = __builtin_alloca (13);
+ aligned i;
+
+ if (bar (p) || bar (&i))
+ abort ();
+}
+
+/* { dg-final { scan-rtl-dump-times "0 uses" 0 "bbro"} } */
+/* { dg-final { scan-rtl-dump-times "ADVANCING TO" 2 "sched2"} } */
+/* { dg-final { cleanup-rtl-dump "bbro" } } */
+/* { dg-final { cleanup-rtl-dump "sched2" } } */
+
