http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45354
Alexander Monakov <amonakov at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
AssignedTo|unassigned at gcc dot |amonakov at gcc dot gnu.org
|gnu.org |
--- Comment #9 from Alexander Monakov <amonakov at gcc dot gnu.org> 2010-11-29
13:58:45 UTC ---
Thanks. We go over-eager when cleaning up degenerate jumps and don't pay
attention to EDGE_CROSSING.
diff --git a/gcc/sel-sched-ir.c b/gcc/sel-sched-ir.c
index 7956cd8..0adc836 100644
--- a/gcc/sel-sched-ir.c
+++ b/gcc/sel-sched-ir.c
@@ -156,6 +156,7 @@ static void move_bb_info (basic_block, basic_block);
static void remove_empty_bb (basic_block, bool);
static void sel_merge_blocks (basic_block, basic_block);
static void sel_remove_loop_preheader (void);
+static bool have_removable_jump_p (basic_block, basic_block);
static bool insn_is_the_only_one_in_bb_p (insn_t);
static void create_initial_data_sets (basic_block);
@@ -3675,7 +3676,7 @@ tidy_control_flow (basic_block xbb, bool full_tidying)
return changed;
/* Check if there is a unnecessary jump after insn left. */
- if (jump_leads_only_to_bb_p (BB_END (xbb), xbb->next_bb)
+ if (have_removable_jump_p (xbb, xbb->next_bb)
&& INSN_SCHED_TIMES (BB_END (xbb)) == 0
&& !IN_CURRENT_FENCE_P (BB_END (xbb)))
{
@@ -3716,7 +3717,7 @@ tidy_control_flow (basic_block xbb, bool full_tidying)
/* And unconditional jump in previous basic block leads to
next basic block of XBB and this jump can be safely removed. */
&& in_current_region_p (xbb->prev_bb)
- && jump_leads_only_to_bb_p (BB_END (xbb->prev_bb), xbb->next_bb)
+ && have_removable_jump_p (xbb->prev_bb, xbb->next_bb)
&& INSN_SCHED_TIMES (BB_END (xbb->prev_bb)) == 0
/* Also this jump is not at the scheduling boundary. */
&& !IN_CURRENT_FENCE_P (BB_END (xbb->prev_bb)))
@@ -6104,11 +6105,13 @@ sel_is_loop_preheader_p (basic_block bb)
return false;
}
-/* Checks whether JUMP leads to basic block DEST_BB and no other blocks. */
-bool
-jump_leads_only_to_bb_p (insn_t jump, basic_block dest_bb)
+/* Check whether JUMP_BB ends with a jump insn that leads only to DEST_BB and
+ can be removed, making the corresponding edge fallthrough (assuming that
+ all basic blocks between JUMP_BB and DEST_BB are empty). */
+static bool
+have_removable_jump_p (basic_block jump_bb, basic_block dest_bb)
{
- basic_block jump_bb = BLOCK_FOR_INSN (jump);
+ insn_t jump = BB_END (jump_bb);
/* It is not jump, jump with side-effects or jump can lead to several
basic blocks. */
@@ -6119,7 +6122,7 @@ jump_leads_only_to_bb_p (insn_t jump, basic_block
dest_bb)
/* Several outgoing edges, abnormal edge or destination of jump is
not DEST_BB. */
if (EDGE_COUNT (jump_bb->succs) != 1
- || EDGE_SUCC (jump_bb, 0)->flags & EDGE_ABNORMAL
+ || EDGE_SUCC (jump_bb, 0)->flags & (EDGE_ABNORMAL | EDGE_CROSSING)
|| EDGE_SUCC (jump_bb, 0)->dest != dest_bb)
return false;
@@ -6199,7 +6202,7 @@ sel_remove_loop_preheader (void)
basic block if it becomes empty. */
if (next_bb->prev_bb == prev_bb
&& prev_bb != ENTRY_BLOCK_PTR
- && jump_leads_only_to_bb_p (BB_END (prev_bb), next_bb))
+ && have_removable_jump_p (prev_bb, next_bb))
{
redirect_edge_and_branch (EDGE_SUCC (prev_bb, 0), next_bb);
if (BB_END (prev_bb) == bb_note (prev_bb))
diff --git a/gcc/sel-sched-ir.h b/gcc/sel-sched-ir.h
index 9ab0466..1f3dec4 100644
--- a/gcc/sel-sched-ir.h
+++ b/gcc/sel-sched-ir.h
@@ -1590,7 +1590,6 @@ extern bool sel_remove_insn (insn_t, bool, bool);
extern bool bb_header_p (insn_t);
extern void sel_init_invalid_data_sets (insn_t);
extern bool insn_at_boundary_p (insn_t);
-extern bool jump_leads_only_to_bb_p (insn_t, basic_block);
/* Basic block and CFG functions. */
