Hi, Can someone review the patch for #829: https://bugs.open64.net/show_bug.cgi?id=829
There is a WHILE_DO loop in the case. In CFG construction, a BB_LOOP
will be created and attached to the following BB_NODE:
_start: BB6 (empty)
_body: BB7 (label for loopback of the WHILE_DO)
_cond: BB10 (cond and TRUEBR to BB7)
The CFG is:
BB1
|
BB2
/ \
+-----> BB3 BB4
| \ /
| BB5 ---> BB12
| |
| BB6
| |
| BB7 <-------+
| | |
+--------- BB8 |
| |
BB9 |
| |
BB10 ------+
|
BB11
|
BB12 <-- BB5
|
BB13 (RETURN)
After MainOPT CFG transformation, BB3 and BB5 is cloned and new CFG is
BB1
|
BB2
/ \
BB14 BB4
| |
BB12 <-- BB15 BB17 --> BB12
| |
BB18 BB19
\ /
+-----------> BB6
| |
| BB7 <-------+
| | |
BB5 <-BB3 <- BB8 |
| |
BB9 |
| |
BB10 ------+
|
BB11
|
BB12 <-- BB5, BB15, BB17
|
BB13 (RETURN)
There will be two loops (6, 7, 8, 3, 5, 9, 10) and (7, 8, 9, 10).
In CFG::Analyze_loops() in opt_cfg.cxx, when call
Fix_SCF_for_mainopt() on BB7, it will set its start/end/step/merge
with the same BB_LOOP*:
5466 BB_LOOP *loop = bb->Loop();
5467 if (loop != NULL && loop->Header() == bb) {
5468 if (loop->End() != NULL) {
5469 if(loop->Start())
5470 loop->Start()->Set_loop(loop);
5471 else {
5472 Is_True(loop->Is_flag_set(LOOP_PRE_WHILE),("wrong
non bottom test loop lowering\n"));
5473 }
5474 loop->End()->Set_loop(loop);
5475 loop->Body()->Set_loop(loop);
5476 if (loop->Step())
5477 loop->Step()->Set_loop(loop);
After calling this function, BB6 and BB7 will share the same BB_LOOP
info. In Find_real_loops(), Collect_loop_body() will be called on both
BB6 and BB7 with the same BB_LOOP*. BB10 will be added to the
BB_LOOP's True_body_set twice. An assertion will happen in the second
time.
In existing code, we already cleaned some of the fields, like the
child, parent, preheader, tail, loopback, etc
5397 static BB_LOOP *
5398 Allocate_loop(BB_NODE *bb, BB_LOOP *parent, CFG *cfg)
5399 {
5400 BB_LOOP *loop = bb->Loop();
5401 if (loop == NULL)
5402 loop = CXX_NEW( BB_LOOP(NULL, NULL, NULL, NULL, NULL, NULL),
5403 cfg->Mem_pool() );
5404 loop->Set_true_body_set(CXX_NEW(BB_NODE_SET(cfg->Total_bb_count(),
cfg,
5405 cfg->Mem_pool(),
BBNS_EMPTY),
5406 cfg->Mem_pool()));
5407 loop->Set_body_set(NULL); // body_set not supported in mainopt
5408 loop->Set_header(bb);
5409 loop->Set_child(NULL);
5410 loop->Set_parent(NULL);
5411 loop->Set_depth(0);
5412 loop->Set_max_depth(0);
5413 Update_loops_for_mainopt(loop);
5414 return loop;
5415 }
5230 void Update_loops_for_mainopt(BB_LOOP *loop)
5231 {
5232 // loop->Header() must be defined
5233
5234 loop->Set_loopback(NULL);
5235 loop->Set_preheader(NULL);
5236 loop->Set_tail(NULL);
5237 loop->Reset_well_formed();
5238
5239 loop->Set_test_at_entry(false);
5240 loop->Set_test_at_exit(false);
5241 loop->Set_exit_early(true);
5242
To fix this issue, I think we need to clear all necessary field in
BB_LOOP when we call Update_loops_for_mainopt():
Index: ../osprey/be/opt/opt_cfg.cxx
===================================================================
--- ../osprey/be/opt/opt_cfg.cxx (revision 3648)
+++ ../osprey/be/opt/opt_cfg.cxx (working copy)
@@ -5231,6 +5231,12 @@
{
// loop->Header() must be defined
+ loop->Set_start(NULL);
+ loop->Set_end(NULL);
+ loop->Set_body(NULL);
+ loop->Set_step(NULL);
+ loop->Set_merge(NULL);
+
loop->Set_loopback(NULL);
loop->Set_preheader(NULL);
loop->Set_tail(NULL);
--
Regards,
Lai Jian-Xin
829.patch
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