On 02/12/11 11:40, Richard Sandiford wrote:
> Tom de Vries <tom_devr...@mentor.com> writes:
>> On 27/11/11 23:59, Eric Botcazou wrote:
>>>> No, DELETED_LABEL notes still work just fine. It depends on how you
>>>> remove the label and replace it with a note, and Tom isn't showing
>>>> what he did, so...
>>>
>>> I agree that there is no obvious reason why just calling delete_insn would
>>> not
>>> work, so this should be investigated first.
>>>
>>
>> The reason it didn't work, is because after turning a label into a
>> NOTE_INSN_DELETED_LABEL, one needs to move it to after the
>> NOTE_INSN_BASIC_BLOCK
>> as in cfgcleanup.c:try_optimize_cfg():
>> ...
>> delete_insn_chain (label, label, false);
>> /* If the case label is undeletable, move it after the
>> BASIC_BLOCK note. */
>> if (NOTE_KIND (BB_HEAD (b)) == NOTE_INSN_DELETED_LABEL)
>> {
>> rtx bb_note = NEXT_INSN (BB_HEAD (b));
>>
>> reorder_insns_nobb (label, label, bb_note);
>> BB_HEAD (b) = bb_note;
>> if (BB_END (b) == bb_note)
>> BB_END (b) = label;
>> }
>> ...
>>
>> Attached patch factors out this piece of code and reuses it in
>> fixup_reorder_chain.
>
> But isn't...
>
>> @@ -2637,15 +2658,7 @@ try_optimize_cfg (int mode)
>> delete_insn_chain (label, label, false);
>> /* If the case label is undeletable, move it after the
>> BASIC_BLOCK note. */
>> - if (NOTE_KIND (BB_HEAD (b)) == NOTE_INSN_DELETED_LABEL)
>> - {
>> - rtx bb_note = NEXT_INSN (BB_HEAD (b));
>> -
>> - reorder_insns_nobb (label, label, bb_note);
>> - BB_HEAD (b) = bb_note;
>> - if (BB_END (b) == bb_note)
>> - BB_END (b) = label;
>> - }
>> + fixup_deleted_label (b);
>
> ...this "delete_insn_chain (label, label, false);" call equivalent
> to "delete_insn (label)"?
Indeed, it is.
> Splitting the operation in two here and:
>
>> Index: gcc/cfglayout.c
>> ===================================================================
>> --- gcc/cfglayout.c (revision 181652)
>> +++ gcc/cfglayout.c (working copy)
>> @@ -857,6 +857,12 @@ 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
>> + && single_pred_p (e_taken->dest))
>> + {
>> + delete_insn (ret_label);
>> + fixup_deleted_label (e_taken->dest);
>> + }
>
> ...here seems a little odd.
>
> Richard
OK, factored out delete_label now.
Bootstrapped and reg-tested on x86_64.
Ok for next stage1?
Thanks,
- Tom
2011-12-03 Tom de Vries <t...@codesourcery.com>
* cfgcleanup.c (delete_label): New function, factored out of ...
(try_optimize_cfg): Use deleted_label.
* basic-block.h (delete_label): Declare.
* cfglayout.c (fixup_reorder_chain): Delete unused label using
delete_label.
* gcc.dg/superblock.c: New test.
Index: gcc/cfgcleanup.c
===================================================================
--- gcc/cfgcleanup.c (revision 181172)
+++ gcc/cfgcleanup.c (working copy)
@@ -2518,6 +2518,39 @@ trivially_empty_bb_p (basic_block bb)
}
}
+/* Delete the label at the head of BB, and if that results in a DELETED_LABEL
+ note, move it after the BASIC_BLOCK note of BB. */
+
+void
+delete_label (basic_block bb)
+{
+ rtx label = BB_HEAD (bb), deleted_label, bb_note;
+ gcc_assert (LABEL_P (label));
+
+ /* Delete the label. */
+ delete_insn (label);
+ if (dump_file)
+ fprintf (dump_file, "Deleted label in block %i.\n",
+ bb->index);
+
+ /* Find the DELETED_LABEL note. */
+ deleted_label = BB_HEAD (bb);
+ if (deleted_label == NULL_RTX
+ || !NOTE_P (deleted_label)
+ || NOTE_KIND (deleted_label) != NOTE_INSN_DELETED_LABEL)
+ return;
+
+ /* Find the BASIC_BLOCK note. */
+ bb_note = NEXT_INSN (deleted_label);
+ gcc_assert (bb_note != NULL_RTX && NOTE_INSN_BASIC_BLOCK_P (bb_note));
+
+ /* Move the DELETED_LABEL note after the BASIC_BLOCK note. */
+ reorder_insns_nobb (deleted_label, deleted_label, bb_note);
+ BB_HEAD (bb) = bb_note;
+ if (BB_END (bb) == bb_note)
+ BB_END (bb) = deleted_label;
+}
+
/* Do simple CFG optimizations - basic block merging, simplifying of jump
instructions etc. Return nonzero if changes were made. */
@@ -2631,25 +2664,7 @@ try_optimize_cfg (int mode)
|| !JUMP_P (BB_END (single_pred (b)))
|| ! label_is_jump_target_p (BB_HEAD (b),
BB_END (single_pred (b)))))
- {
- rtx label = BB_HEAD (b);
-
- delete_insn_chain (label, label, false);
- /* If the case label is undeletable, move it after the
- BASIC_BLOCK note. */
- if (NOTE_KIND (BB_HEAD (b)) == NOTE_INSN_DELETED_LABEL)
- {
- rtx bb_note = NEXT_INSN (BB_HEAD (b));
-
- reorder_insns_nobb (label, label, bb_note);
- BB_HEAD (b) = bb_note;
- if (BB_END (b) == bb_note)
- BB_END (b) = label;
- }
- if (dump_file)
- fprintf (dump_file, "Deleted label in block %i.\n",
- b->index);
- }
+ delete_label (b);
/* If we fall through an empty block, we can remove it. */
if (!(mode & CLEANUP_CFGLAYOUT)
Index: gcc/cfglayout.c
===================================================================
--- gcc/cfglayout.c (revision 181172)
+++ gcc/cfglayout.c (working copy)
@@ -857,6 +857,9 @@ 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
+ && single_pred_p (e_taken->dest))
+ delete_label (e_taken->dest);
continue;
}
}
Index: gcc/basic-block.h
===================================================================
--- gcc/basic-block.h (revision 181172)
+++ gcc/basic-block.h (working copy)
@@ -813,6 +813,7 @@ extern void rtl_make_eh_edge (sbitmap, b
enum replace_direction { dir_none, dir_forward, dir_backward, dir_both };
/* In cfgcleanup.c. */
+extern void delete_label (basic_block);
extern bool cleanup_cfg (int);
extern int flow_find_cross_jump (basic_block, basic_block, rtx *, rtx *,
enum replace_direction*);
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" } } */
+
