On 05/30/2012 10:44 AM, Jason Merrill wrote:
The code in build_new_1 already knows how to handle an initializer that
it was unable to stabilize, but the logic was backwards in a critical
place. I'm surprised this typo hasn't been hit before since it was
introduced in 2006...
...and then this patch fixes stabilize_init to actually stabilize the
initializer in this case. And fixes another case I noticed that has
been ICEing since 4.0.
Tested x86_64-pc-linux-gnu, applying to trunk. I'm not going to apply
it to 4.7 because nobody has noticed the other issue.
commit 3f176267c61a889926e3f518ccd79cf55c5e7de1
Author: Jason Merrill <ja...@redhat.com>
Date: Wed May 30 17:31:57 2012 -0400
PR c++/53356
* tree.c (stabilize_init): Handle stabilizing a TARGET_EXPR
representing a bitwise copy of a glvalue.
diff --git a/gcc/cp/tree.c b/gcc/cp/tree.c
index 4e7056f..2b541cd 100644
--- a/gcc/cp/tree.c
+++ b/gcc/cp/tree.c
@@ -3389,7 +3389,7 @@ stabilize_aggr_init (tree call, tree *initp)
takes care not to introduce additional temporaries.
Returns TRUE iff the expression was successfully pre-evaluated,
- i.e., if INIT is now side-effect free, except for, possible, a
+ i.e., if INIT is now side-effect free, except for, possibly, a
single call to a constructor. */
bool
@@ -3402,21 +3402,37 @@ stabilize_init (tree init, tree *initp)
if (t == error_mark_node || processing_template_decl)
return true;
- if (TREE_CODE (t) == INIT_EXPR
- && TREE_CODE (TREE_OPERAND (t, 1)) != TARGET_EXPR
- && TREE_CODE (TREE_OPERAND (t, 1)) != CONSTRUCTOR
- && TREE_CODE (TREE_OPERAND (t, 1)) != AGGR_INIT_EXPR)
- {
- TREE_OPERAND (t, 1) = stabilize_expr (TREE_OPERAND (t, 1), initp);
- return true;
- }
-
if (TREE_CODE (t) == INIT_EXPR)
t = TREE_OPERAND (t, 1);
if (TREE_CODE (t) == TARGET_EXPR)
t = TARGET_EXPR_INITIAL (t);
- if (TREE_CODE (t) == COMPOUND_EXPR)
- t = expr_last (t);
+
+ /* If the RHS can be stabilized without breaking copy elision, stabilize
+ it. We specifically don't stabilize class prvalues here because that
+ would mean an extra copy, but they might be stabilized below. */
+ if (TREE_CODE (init) == INIT_EXPR
+ && TREE_CODE (t) != CONSTRUCTOR
+ && TREE_CODE (t) != AGGR_INIT_EXPR
+ && (SCALAR_TYPE_P (TREE_TYPE (t))
+ || lvalue_or_rvalue_with_address_p (t)))
+ {
+ TREE_OPERAND (init, 1) = stabilize_expr (t, initp);
+ return true;
+ }
+
+ if (TREE_CODE (t) == COMPOUND_EXPR
+ && TREE_CODE (init) == INIT_EXPR)
+ {
+ tree last = expr_last (t);
+ /* Handle stabilizing the EMPTY_CLASS_EXPR pattern. */
+ if (!TREE_SIDE_EFFECTS (last))
+ {
+ *initp = t;
+ TREE_OPERAND (init, 1) = last;
+ return true;
+ }
+ }
+
if (TREE_CODE (t) == CONSTRUCTOR)
{
/* Aggregate initialization: stabilize each of the field
@@ -3439,11 +3455,6 @@ stabilize_init (tree init, tree *initp)
return good;
}
- /* If the initializer is a COND_EXPR, we can't preevaluate
- anything. */
- if (TREE_CODE (t) == COND_EXPR)
- return false;
-
if (TREE_CODE (t) == CALL_EXPR)
{
stabilize_call (t, initp);
diff --git a/gcc/testsuite/g++.dg/init/new34.C b/gcc/testsuite/g++.dg/init/new34.C
new file mode 100644
index 0000000..9e67eb34
--- /dev/null
+++ b/gcc/testsuite/g++.dg/init/new34.C
@@ -0,0 +1,11 @@
+// PR c++/53356
+
+struct A { A(); ~A(); };
+
+struct B {
+ operator const A () const;
+};
+
+A* cause_ICE() {
+ return new A((A(),A()));
+}
diff --git a/gcc/testsuite/g++.dg/tree-ssa/stabilize1.C b/gcc/testsuite/g++.dg/tree-ssa/stabilize1.C
new file mode 100644
index 0000000..2fe723c
--- /dev/null
+++ b/gcc/testsuite/g++.dg/tree-ssa/stabilize1.C
@@ -0,0 +1,14 @@
+// PR c++/53356
+// { dg-options "-fdump-tree-gimple" }
+// { dg-final { scan-tree-dump-not "= 0" "gimple" } }
+// { dg-final { cleanup-tree-dump "gimple" } }
+
+class A {};
+
+struct B {
+ operator const A &() const;
+};
+
+A* cause_ICE() {
+ return new A(B());
+}
