private_typeinfo: limit is_dst_type_derived_from_static_type optimization
Patch by Ryan Prichard
If the destination type does not derive from the static type, we can skip
the search_above_dst call, but we still need to run the
!does_dst_type_point_to_our_static_type block of code. That block of code
will increment info->number_to_dst_ptr to 2, and because dest isn't derived
from static, the cast will ultimately fail.
Fixes PR33439
Reviewed as https://reviews.llvm.org/D36447
git-svn-id: https://llvm.org/svn/llvm-project/libcxxabi/trunk@332767 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/src/private_typeinfo.cpp b/src/private_typeinfo.cpp
index 6da3c77..a0326a1 100644
--- a/src/private_typeinfo.cpp
+++ b/src/private_typeinfo.cpp
@@ -859,13 +859,14 @@
// Record the access path that got us here
// If there is more than one dst_type this path doesn't matter.
info->path_dynamic_ptr_to_dst_ptr = path_below;
+ bool does_dst_type_point_to_our_static_type = false;
// Only search above here if dst_type derives from static_type, or
// if it is unknown if dst_type derives from static_type.
if (info->is_dst_type_derived_from_static_type != no)
{
// Set up flags to record results from all base classes
bool is_dst_type_derived_from_static_type = false;
- bool does_dst_type_point_to_our_static_type = false;
+
// We've found a dst_type with a potentially public path to here.
// We have to assume the path is public because it may become
// public later (if we get back to here with a public path).
@@ -909,21 +910,6 @@
}
}
}
- if (!does_dst_type_point_to_our_static_type)
- {
- // We found a dst_type that doesn't point to (static_ptr, static_type)
- // So record the address of this dst_ptr and increment the
- // count of the number of such dst_types found in the tree.
- info->dst_ptr_not_leading_to_static_ptr = current_ptr;
- info->number_to_dst_ptr += 1;
- // If there exists another dst with a private path to
- // (static_ptr, static_type), then the cast from
- // (dynamic_ptr, dynamic_type) to dst_type is now ambiguous,
- // so stop search.
- if (info->number_to_static_ptr == 1 &&
- info->path_dst_ptr_to_static_ptr == not_public_path)
- info->search_done = true;
- }
// If we found no static_type,s then dst_type doesn't derive
// from static_type, else it does. Record this result so that
// next time we hit a dst_type we will know not to search above
@@ -932,7 +918,22 @@
info->is_dst_type_derived_from_static_type = yes;
else
info->is_dst_type_derived_from_static_type = no;
- }
+ }
+ if (!does_dst_type_point_to_our_static_type)
+ {
+ // We found a dst_type that doesn't point to (static_ptr, static_type)
+ // So record the address of this dst_ptr and increment the
+ // count of the number of such dst_types found in the tree.
+ info->dst_ptr_not_leading_to_static_ptr = current_ptr;
+ info->number_to_dst_ptr += 1;
+ // If there exists another dst with a private path to
+ // (static_ptr, static_type), then the cast from
+ // (dynamic_ptr, dynamic_type) to dst_type is now ambiguous,
+ // so stop search.
+ if (info->number_to_static_ptr == 1 &&
+ info->path_dst_ptr_to_static_ptr == not_public_path)
+ info->search_done = true;
+ }
}
}
else
@@ -1030,13 +1031,13 @@
// Record the access path that got us here
// If there is more than one dst_type this path doesn't matter.
info->path_dynamic_ptr_to_dst_ptr = path_below;
+ bool does_dst_type_point_to_our_static_type = false;
// Only search above here if dst_type derives from static_type, or
// if it is unknown if dst_type derives from static_type.
if (info->is_dst_type_derived_from_static_type != no)
{
// Set up flags to record results from all base classes
bool is_dst_type_derived_from_static_type = false;
- bool does_dst_type_point_to_our_static_type = false;
// Zero out found flags
info->found_our_static_ptr = false;
info->found_any_static_type = false;
@@ -1047,20 +1048,6 @@
if (info->found_our_static_ptr)
does_dst_type_point_to_our_static_type = true;
}
- if (!does_dst_type_point_to_our_static_type)
- {
- // We found a dst_type that doesn't point to (static_ptr, static_type)
- // So record the address of this dst_ptr and increment the
- // count of the number of such dst_types found in the tree.
- info->dst_ptr_not_leading_to_static_ptr = current_ptr;
- info->number_to_dst_ptr += 1;
- // If there exists another dst with a private path to
- // (static_ptr, static_type), then the cast from
- // (dynamic_ptr, dynamic_type) to dst_type is now ambiguous.
- if (info->number_to_static_ptr == 1 &&
- info->path_dst_ptr_to_static_ptr == not_public_path)
- info->search_done = true;
- }
// If we found no static_type,s then dst_type doesn't derive
// from static_type, else it does. Record this result so that
// next time we hit a dst_type we will know not to search above
@@ -1070,6 +1057,20 @@
else
info->is_dst_type_derived_from_static_type = no;
}
+ if (!does_dst_type_point_to_our_static_type)
+ {
+ // We found a dst_type that doesn't point to (static_ptr, static_type)
+ // So record the address of this dst_ptr and increment the
+ // count of the number of such dst_types found in the tree.
+ info->dst_ptr_not_leading_to_static_ptr = current_ptr;
+ info->number_to_dst_ptr += 1;
+ // If there exists another dst with a private path to
+ // (static_ptr, static_type), then the cast from
+ // (dynamic_ptr, dynamic_type) to dst_type is now ambiguous.
+ if (info->number_to_static_ptr == 1 &&
+ info->path_dst_ptr_to_static_ptr == not_public_path)
+ info->search_done = true;
+ }
}
}
else
diff --git a/test/dynamic_cast.pass.cpp b/test/dynamic_cast.pass.cpp
index cd24798..5288f7c 100644
--- a/test/dynamic_cast.pass.cpp
+++ b/test/dynamic_cast.pass.cpp
@@ -95,9 +95,60 @@
} // t3
+namespace t4
+{
+
+// PR33439
+struct C2 { virtual ~C2() {} Pad1 _; };
+struct C3 { virtual ~C3() {} Pad2 _; };
+struct C4 : C3 { Pad3 _; };
+struct C8 : C2, virtual C4 { Pad4 _; };
+struct C9 : C4, C8 { Pad5 _; };
+
+C9 c9;
+C2 *c2 = &c9;
+
+void test()
+{
+ assert(dynamic_cast<C2*>(c2) == static_cast<C2*>(&c9));
+ assert(dynamic_cast<C3*>(c2) == 0);
+ assert(dynamic_cast<C4*>(c2) == 0);
+ assert(dynamic_cast<C8*>(c2) == static_cast<C8*>(&c9));
+ assert(dynamic_cast<C9*>(c2) == static_cast<C9*>(&c9));
+}
+
+} // t4
+
+namespace t5
+{
+
+// PR33439
+struct Dummy { virtual ~Dummy() {} Pad1 _; };
+struct Src { virtual ~Src() {} Pad2 _; };
+struct Dest : Dummy { Pad3 _; };
+struct A1 : Dest { Pad4 _; };
+struct A2 : Dest { Pad5 _; };
+struct Root : Src, A1, A2 { Pad6 _; };
+
+Root root;
+Src *src = &root;
+
+void test()
+{
+ assert(dynamic_cast<Dummy*>(src) == 0);
+ assert(dynamic_cast<Src*>(src) == static_cast<Src*>(&root));
+ assert(dynamic_cast<Dest*>(src) == 0);
+ assert(dynamic_cast<A1*>(src) == static_cast<A1*>(&root));
+ assert(dynamic_cast<A2*>(src) == static_cast<A2*>(&root));
+}
+
+} // t5
+
int main()
{
t1::test();
t2::test();
t3::test();
+ t4::test();
+ t5::test();
}
