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re PR c++/34949 (Dead code in empty destructors.) 

PR c++/34949
	PR c++/50243
	* tree-eh.c (optimize_clobbers): Only remove clobbers if bb doesn't
	contain anything but clobbers, at most one __builtin_stack_restore,
	optionally debug stmts and final resx, and if it has at least one
	incoming EH edge.  Don't check for SSA_NAME on LHS of a clobber.
	(sink_clobbers): Don't check for SSA_NAME on LHS of a clobber.
	Instead of moving clobbers with MEM_REF LHS with SSA_NAME address
	which isn't defaut definition, remove them.
	(unsplit_eh, cleanup_empty_eh): Use single_{pred,succ}_{p,edge}
	instead of EDGE_COUNT comparisons or EDGE_{PRED,SUCC}.
	* tree-ssa-ccp.c (execute_fold_all_builtins): Remove clobbers
	with MEM_REF LHS with SSA_NAME address.

	* g++.dg/opt/vt3.C: New test.
	* g++.dg/opt/vt4.C: New test.

From-SVN: r197580
This commit is contained in:
Jakub Jelinek 2013-04-08 15:46:00 +02:00
parent 4481581f34
commit f223bb1362
6 changed files with 171 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
gcc/ChangeLog
View File

@ -1,3 +1,19 @@
2013-04-08 Jakub Jelinek <jakub@redhat.com>
PR c++/34949
PR c++/50243
* tree-eh.c (optimize_clobbers): Only remove clobbers if bb doesn't
contain anything but clobbers, at most one __builtin_stack_restore,
optionally debug stmts and final resx, and if it has at least one
incoming EH edge. Don't check for SSA_NAME on LHS of a clobber.
(sink_clobbers): Don't check for SSA_NAME on LHS of a clobber.
Instead of moving clobbers with MEM_REF LHS with SSA_NAME address
which isn't defaut definition, remove them.
(unsplit_eh, cleanup_empty_eh): Use single_{pred,succ}_{p,edge}
instead of EDGE_COUNT comparisons or EDGE_{PRED,SUCC}.
* tree-ssa-ccp.c (execute_fold_all_builtins): Remove clobbers
with MEM_REF LHS with SSA_NAME address.
2013-04-08 Jeff Law <law@redhat.com>
* gimple.c (canonicalize_cond_expr_cond): Rewrite x ^ y into x != y.

9
gcc/testsuite/ChangeLog
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@ -1,6 +1,13 @@
2013-04-08 Jakub Jelinek <jakub@redhat.com>
PR c++/34949
PR c++/50243
* g++.dg/opt/vt3.C: New test.
* g++.dg/opt/vt4.C: New test.
2013-04-08 Jeff Law <law@redhat.com>
* gcc.dg/tree-ssa/forwprop-25.c: New test
* gcc.dg/tree-ssa/forwprop-25.c: New test.
2013-04-08 Richard Biener <rguenther@suse.de>

43
gcc/testsuite/g++.dg/opt/vt3.C Normal file
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@ -0,0 +1,43 @@
// PR c++/34949
// { dg-do compile }
// { dg-options "-O3" }
struct E {};
struct A
{
virtual void a (void *) = 0;
};
struct B
{
virtual ~B () {};
unsigned int b1;
E **b2;
A *b3;
};
struct C : public B
{
~C ();
};
C::~C ()
{
for (unsigned int i = 0; i < b1; i++)
b3->a (b2);
}
struct D
{
~D () {}
C d;
};
struct F { virtual ~F () {}; };
struct G { void g (); };
struct H : public F
{
virtual ~H ();
D *h1;
G *h2;
};
H::~H ()
{
h2->g ();
delete h1;
}

31
gcc/testsuite/g++.dg/opt/vt4.C Normal file
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@ -0,0 +1,31 @@
// PR c++/50243
// { dg-do compile }
// { dg-options "-O" }
// { dg-final { scan-assembler-not "_ZTV.A" } }
void foo ();
struct A
{
~A () { }
virtual void a () = 0;
virtual void b () = 0;
virtual void c () = 0;
};
struct B : public A
{
~B () { foo (); }
void a () { foo (); }
void b () { foo (); }
void c () { delete this; }
};
void
test ()
{
A *y = new B ();
y->a ();
y->b ();
y->c ();
}

67
gcc/tree-eh.c
View File

@ -3230,14 +3230,48 @@ static void
optimize_clobbers (basic_block bb)
{
gimple_stmt_iterator gsi = gsi_last_bb (bb);
bool any_clobbers = false;
bool seen_stack_restore = false;
edge_iterator ei;
edge e;
/* Only optimize anything if the bb contains at least one clobber,
ends with resx (checked by caller), optionally contains some
debug stmts or labels, or at most one __builtin_stack_restore
call, and has an incoming EH edge. */
for (gsi_prev (&gsi); !gsi_end_p (gsi); gsi_prev (&gsi))
{
gimple stmt = gsi_stmt (gsi);
if (is_gimple_debug (stmt))
continue;
if (!gimple_clobber_p (stmt)
|| TREE_CODE (gimple_assign_lhs (stmt)) == SSA_NAME)
return;
if (gimple_clobber_p (stmt))
{
any_clobbers = true;
continue;
}
if (!seen_stack_restore
&& gimple_call_builtin_p (stmt, BUILT_IN_STACK_RESTORE))
{
seen_stack_restore = true;
continue;
}
if (gimple_code (stmt) == GIMPLE_LABEL)
break;
return;
}
if (!any_clobbers)
return;
FOR_EACH_EDGE (e, ei, bb->preds)
if (e->flags & EDGE_EH)
break;
if (e == NULL)
return;
gsi = gsi_last_bb (bb);
for (gsi_prev (&gsi); !gsi_end_p (gsi); gsi_prev (&gsi))
{
gimple stmt = gsi_stmt (gsi);
if (!gimple_clobber_p (stmt))
continue;
unlink_stmt_vdef (stmt);
gsi_remove (&gsi, true);
release_defs (stmt);
@ -3278,8 +3312,7 @@ sink_clobbers (basic_block bb)
continue;
if (gimple_code (stmt) == GIMPLE_LABEL)
break;
if (!gimple_clobber_p (stmt)
|| TREE_CODE (gimple_assign_lhs (stmt)) == SSA_NAME)
if (!gimple_clobber_p (stmt))
return 0;
any_clobbers = true;
}
@ -3292,11 +3325,27 @@ sink_clobbers (basic_block bb)
for (gsi_prev (&gsi); !gsi_end_p (gsi); gsi_prev (&gsi))
{
gimple stmt = gsi_stmt (gsi);
tree lhs;
if (is_gimple_debug (stmt))
continue;
if (gimple_code (stmt) == GIMPLE_LABEL)
break;
unlink_stmt_vdef (stmt);
lhs = gimple_assign_lhs (stmt);
/* Unfortunately we don't have dominance info updated at this
point, so checking if
dominated_by_p (CDI_DOMINATORS, succbb,
gimple_bb (SSA_NAME_DEF_STMT (TREE_OPERAND (lhs, 0)))
would be too costly. Thus, avoid sinking any clobbers that
refer to non-(D) SSA_NAMEs. */
if (TREE_CODE (lhs) == MEM_REF
&& TREE_CODE (TREE_OPERAND (lhs, 0)) == SSA_NAME
&& !SSA_NAME_IS_DEFAULT_DEF (TREE_OPERAND (lhs, 0)))
{
gsi_remove (&gsi, true);
release_defs (stmt);
continue;
}
gsi_remove (&gsi, false);
/* Trigger the operand scanner to cause renaming for virtual
operands for this statement.
@ -3737,10 +3786,10 @@ unsplit_eh (eh_landing_pad lp)
edge e_in, e_out;
/* Quickly check the edge counts on BB for singularity. */
if (EDGE_COUNT (bb->preds) != 1 || EDGE_COUNT (bb->succs) != 1)
if (!single_pred_p (bb) || !single_succ_p (bb))
return false;
e_in = EDGE_PRED (bb, 0);
e_out = EDGE_SUCC (bb, 0);
e_in = single_pred_edge (bb);
e_out = single_succ_edge (bb);
/* Input edge must be EH and output edge must be normal. */
if ((e_in->flags & EDGE_EH) == 0 || (e_out->flags & EDGE_EH) != 0)
@ -4142,7 +4191,7 @@ cleanup_empty_eh (eh_landing_pad lp)
e_out = NULL;
break;
case 1:
e_out = EDGE_SUCC (bb, 0);
e_out = single_succ_edge (bb);
break;
default:
return false;

15
gcc/tree-ssa-ccp.c
View File

@ -2396,6 +2396,21 @@ execute_fold_all_builtins (void)
if (gimple_code (stmt) != GIMPLE_CALL)
{
/* Remove all *ssaname_N ={v} {CLOBBER}; stmts,
after the last GIMPLE DSE they aren't needed and might
unnecessarily keep the SSA_NAMEs live. */
if (gimple_clobber_p (stmt))
{
tree lhs = gimple_assign_lhs (stmt);
if (TREE_CODE (lhs) == MEM_REF
&& TREE_CODE (TREE_OPERAND (lhs, 0)) == SSA_NAME)
{
unlink_stmt_vdef (stmt);
gsi_remove (&i, true);
release_defs (stmt);
continue;
}
}
gsi_next (&i);
continue;
}