blob: e7b49b99504eb94202f9fa48f4b288457e31060f [file] [log] [blame]
//===----------------------- private_typeinfo.cpp -------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "private_typeinfo.h"
// The flag _LIBCXX_DYNAMIC_FALLBACK is used to make dynamic_cast more
// forgiving when type_info's mistakenly have hidden visibility and thus
// multiple type_infos can exist for a single type.
//
// When _LIBCXX_DYNAMIC_FALLBACK is defined, and only in the case where
// there is a detected inconsistency in the type_info hierarchy during a
// dynamic_cast, then the equality operation will fall back to using strcmp
// on type_info names to determine type_info equality.
//
// This change happens *only* under dynamic_cast, and only when
// dynamic_cast is faced with the choice: abort, or possibly give back the
// wrong answer. If when the dynamic_cast is done with this fallback
// algorithm and an inconsistency is still detected, dynamic_cast will call
// abort with an appropriate message.
//
// The current implementation of _LIBCXX_DYNAMIC_FALLBACK requires a
// printf-like function called syslog:
//
// void syslog(int facility_priority, const char* format, ...);
//
// If you want this functionality but your platform doesn't have syslog,
// just implement it in terms of fprintf(stderr, ...).
//
// _LIBCXX_DYNAMIC_FALLBACK is currently off by default.
#if _LIBCXX_DYNAMIC_FALLBACK
#include "abort_message.h"
#include <string.h>
#include <sys/syslog.h>
#endif
// On Windows, typeids are different between DLLs and EXEs, so comparing
// type_info* will work for typeids from the same compiled file but fail
// for typeids from a DLL and an executable. Among other things, exceptions
// are not caught by handlers since can_catch() returns false.
//
// Defining _LIBCXX_DYNAMIC_FALLBACK does not help since can_catch() calls
// is_equal() with use_strcmp=false so the string names are not compared.
#ifdef _WIN32
#include <string.h>
#endif
namespace __cxxabiv1
{
#pragma GCC visibility push(hidden)
#if _LIBCXX_DYNAMIC_FALLBACK
inline
bool
is_equal(const std::type_info* x, const std::type_info* y, bool use_strcmp)
{
if (!use_strcmp)
return x == y;
return strcmp(x->name(), y->name()) == 0;
}
#else // !_LIBCXX_DYNAMIC_FALLBACK
inline
bool
is_equal(const std::type_info* x, const std::type_info* y, bool)
{
#ifndef _WIN32
return x == y;
#else
return (x == y) || (strcmp(x->name(), y->name()) == 0);
#endif
}
#endif // _LIBCXX_DYNAMIC_FALLBACK
// __shim_type_info
__shim_type_info::~__shim_type_info()
{
}
void __shim_type_info::noop1() const {}
void __shim_type_info::noop2() const {}
// __fundamental_type_info
// This miraculously (compiler magic) emits the type_info's for:
// 1. all of the fundamental types
// 2. pointers to all of the fundamental types
// 3. pointers to all of the const fundamental types
__fundamental_type_info::~__fundamental_type_info()
{
}
// __array_type_info
__array_type_info::~__array_type_info()
{
}
// __function_type_info
__function_type_info::~__function_type_info()
{
}
// __enum_type_info
__enum_type_info::~__enum_type_info()
{
}
// __class_type_info
__class_type_info::~__class_type_info()
{
}
// __si_class_type_info
__si_class_type_info::~__si_class_type_info()
{
}
// __vmi_class_type_info
__vmi_class_type_info::~__vmi_class_type_info()
{
}
// __pbase_type_info
__pbase_type_info::~__pbase_type_info()
{
}
// __pointer_type_info
__pointer_type_info::~__pointer_type_info()
{
}
// __pointer_to_member_type_info
__pointer_to_member_type_info::~__pointer_to_member_type_info()
{
}
// can_catch
// A handler is a match for an exception object of type E if
// 1. The handler is of type cv T or cv T& and E and T are the same type
// (ignoring the top-level cv-qualifiers), or
// 2. the handler is of type cv T or cv T& and T is an unambiguous public
// base class of E, or
// 3. the handler is of type cv1 T* cv2 and E is a pointer type that can be
// converted to the type of the handler by either or both of
// A. a standard pointer conversion (4.10) not involving conversions to
// pointers to private or protected or ambiguous classes
// B. a qualification conversion
// 4. the handler is a pointer or pointer to member type and E is
// std::nullptr_t.
// adjustedPtr:
//
// catch (A& a) : adjustedPtr == &a
// catch (A* a) : adjustedPtr == a
// catch (A** a) : adjustedPtr == a
//
// catch (D2& d2) : adjustedPtr == &d2 (d2 is base class of thrown object)
// catch (D2* d2) : adjustedPtr == d2
// catch (D2*& d2) : adjustedPtr == d2
//
// catch (...) : adjustedPtr == & of the exception
// Handles bullet 1
bool
__fundamental_type_info::can_catch(const __shim_type_info* thrown_type,
void*&) const
{
return is_equal(this, thrown_type, false);
}
bool
__array_type_info::can_catch(const __shim_type_info*, void*&) const
{
// We can get here if someone tries to catch an array by reference.
// However if someone tries to throw an array, it immediately gets
// converted to a pointer, which will not convert back to an array
// at the catch clause. So this can never catch anything.
return false;
}
bool
__function_type_info::can_catch(const __shim_type_info*, void*&) const
{
// We can get here if someone tries to catch a function by reference.
// However if someone tries to throw a function, it immediately gets
// converted to a pointer, which will not convert back to a function
// at the catch clause. So this can never catch anything.
return false;
}
// Handles bullet 1
bool
__enum_type_info::can_catch(const __shim_type_info* thrown_type,
void*&) const
{
return is_equal(this, thrown_type, false);
}
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wmissing-field-initializers"
// Handles bullets 1 and 2
bool
__class_type_info::can_catch(const __shim_type_info* thrown_type,
void*& adjustedPtr) const
{
// bullet 1
if (is_equal(this, thrown_type, false))
return true;
const __class_type_info* thrown_class_type =
dynamic_cast<const __class_type_info*>(thrown_type);
if (thrown_class_type == 0)
return false;
// bullet 2
__dynamic_cast_info info = {thrown_class_type, 0, this, -1, 0};
info.number_of_dst_type = 1;
thrown_class_type->has_unambiguous_public_base(&info, adjustedPtr, public_path);
if (info.path_dst_ptr_to_static_ptr == public_path)
{
adjustedPtr = const_cast<void*>(info.dst_ptr_leading_to_static_ptr);
return true;
}
return false;
}
#pragma clang diagnostic pop
void
__class_type_info::process_found_base_class(__dynamic_cast_info* info,
void* adjustedPtr,
int path_below) const
{
if (info->dst_ptr_leading_to_static_ptr == 0)
{
// First time here
info->dst_ptr_leading_to_static_ptr = adjustedPtr;
info->path_dst_ptr_to_static_ptr = path_below;
info->number_to_static_ptr = 1;
}
else if (info->dst_ptr_leading_to_static_ptr == adjustedPtr)
{
// We've been here before. Update path to "most public"
if (info->path_dst_ptr_to_static_ptr == not_public_path)
info->path_dst_ptr_to_static_ptr = path_below;
}
else
{
// We've detected an ambiguous cast from (thrown_class_type, adjustedPtr)
// to a static_type
info->number_to_static_ptr += 1;
info->path_dst_ptr_to_static_ptr = not_public_path;
info->search_done = true;
}
}
void
__class_type_info::has_unambiguous_public_base(__dynamic_cast_info* info,
void* adjustedPtr,
int path_below) const
{
if (is_equal(this, info->static_type, false))
process_found_base_class(info, adjustedPtr, path_below);
}
void
__si_class_type_info::has_unambiguous_public_base(__dynamic_cast_info* info,
void* adjustedPtr,
int path_below) const
{
if (is_equal(this, info->static_type, false))
process_found_base_class(info, adjustedPtr, path_below);
else
__base_type->has_unambiguous_public_base(info, adjustedPtr, path_below);
}
void
__base_class_type_info::has_unambiguous_public_base(__dynamic_cast_info* info,
void* adjustedPtr,
int path_below) const
{
ptrdiff_t offset_to_base = 0;
if (adjustedPtr != nullptr)
{
offset_to_base = __offset_flags >> __offset_shift;
if (__offset_flags & __virtual_mask)
{
const char* vtable = *static_cast<const char*const*>(adjustedPtr);
offset_to_base = *reinterpret_cast<const ptrdiff_t*>(vtable + offset_to_base);
}
}
__base_type->has_unambiguous_public_base(
info,
static_cast<char*>(adjustedPtr) + offset_to_base,
(__offset_flags & __public_mask) ? path_below : not_public_path);
}
void
__vmi_class_type_info::has_unambiguous_public_base(__dynamic_cast_info* info,
void* adjustedPtr,
int path_below) const
{
if (is_equal(this, info->static_type, false))
process_found_base_class(info, adjustedPtr, path_below);
else
{
typedef const __base_class_type_info* Iter;
const Iter e = __base_info + __base_count;
Iter p = __base_info;
p->has_unambiguous_public_base(info, adjustedPtr, path_below);
if (++p < e)
{
do
{
p->has_unambiguous_public_base(info, adjustedPtr, path_below);
if (info->search_done)
break;
} while (++p < e);
}
}
}
// Handles bullets 1 and 4 for both pointers and member pointers
bool
__pbase_type_info::can_catch(const __shim_type_info* thrown_type,
void*&) const
{
return is_equal(this, thrown_type, false) ||
is_equal(thrown_type, &typeid(std::nullptr_t), false);
}
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wmissing-field-initializers"
// Handles bullets 1, 3 and 4
// NOTE: It might not be safe to adjust the pointer if it is not not a pointer
// type. Only adjust the pointer after we know it is safe to do so.
bool
__pointer_type_info::can_catch(const __shim_type_info* thrown_type,
void*& adjustedPtr) const
{
// bullets 1 and 4
if (__pbase_type_info::can_catch(thrown_type, adjustedPtr)) {
if (adjustedPtr != NULL)
adjustedPtr = *static_cast<void**>(adjustedPtr);
return true;
}
// bullet 3
const __pointer_type_info* thrown_pointer_type =
dynamic_cast<const __pointer_type_info*>(thrown_type);
if (thrown_pointer_type == 0)
return false;
// Do the dereference adjustment
if (adjustedPtr != NULL)
adjustedPtr = *static_cast<void**>(adjustedPtr);
// bullet 3B
if (thrown_pointer_type->__flags & ~__flags)
return false;
if (is_equal(__pointee, thrown_pointer_type->__pointee, false))
return true;
// bullet 3A
if (is_equal(__pointee, &typeid(void), false))
return true;
// Handle pointer to pointer
const __pointer_type_info* nested_pointer_type =
dynamic_cast<const __pointer_type_info*>(__pointee);
if (nested_pointer_type) {
if (~__flags & __const_mask) return false;
return nested_pointer_type->can_catch_nested(thrown_pointer_type->__pointee);
}
// Handle pointer to pointer to member
const __pointer_to_member_type_info* member_ptr_type =
dynamic_cast<const __pointer_to_member_type_info*>(__pointee);
if (member_ptr_type) {
if (~__flags & __const_mask) return false;
return member_ptr_type->can_catch_nested(thrown_pointer_type->__pointee);
}
// Handle pointer to class type
const __class_type_info* catch_class_type =
dynamic_cast<const __class_type_info*>(__pointee);
if (catch_class_type == 0)
return false;
const __class_type_info* thrown_class_type =
dynamic_cast<const __class_type_info*>(thrown_pointer_type->__pointee);
if (thrown_class_type == 0)
return false;
__dynamic_cast_info info = {thrown_class_type, 0, catch_class_type, -1, 0};
info.number_of_dst_type = 1;
thrown_class_type->has_unambiguous_public_base(&info, adjustedPtr, public_path);
if (info.path_dst_ptr_to_static_ptr == public_path)
{
if (adjustedPtr != NULL)
adjustedPtr = const_cast<void*>(info.dst_ptr_leading_to_static_ptr);
return true;
}
return false;
}
bool __pointer_type_info::can_catch_nested(
const __shim_type_info* thrown_type) const
{
const __pointer_type_info* thrown_pointer_type =
dynamic_cast<const __pointer_type_info*>(thrown_type);
if (thrown_pointer_type == 0)
return false;
// bullet 3B
if (thrown_pointer_type->__flags & ~__flags)
return false;
if (is_equal(__pointee, thrown_pointer_type->__pointee, false))
return true;
// If the pointed to types differ then the catch type must be const
// qualified.
if (~__flags & __const_mask)
return false;
// Handle pointer to pointer
const __pointer_type_info* nested_pointer_type =
dynamic_cast<const __pointer_type_info*>(__pointee);
if (nested_pointer_type) {
return nested_pointer_type->can_catch_nested(
thrown_pointer_type->__pointee);
}
// Handle pointer to pointer to member
const __pointer_to_member_type_info* member_ptr_type =
dynamic_cast<const __pointer_to_member_type_info*>(__pointee);
if (member_ptr_type) {
return member_ptr_type->can_catch_nested(thrown_pointer_type->__pointee);
}
return false;
}
bool __pointer_to_member_type_info::can_catch(
const __shim_type_info* thrown_type, void*& adjustedPtr) const {
// bullets 1 and 4
if (__pbase_type_info::can_catch(thrown_type, adjustedPtr))
return true;
const __pointer_to_member_type_info* thrown_pointer_type =
dynamic_cast<const __pointer_to_member_type_info*>(thrown_type);
if (thrown_pointer_type == 0)
return false;
if (thrown_pointer_type->__flags & ~__flags)
return false;
if (!is_equal(__pointee, thrown_pointer_type->__pointee, false))
return false;
if (is_equal(__context, thrown_pointer_type->__context, false))
return true;
__dynamic_cast_info info = {__context, 0, thrown_pointer_type->__context, -1, 0};
info.number_of_dst_type = 1;
__context->has_unambiguous_public_base(&info, adjustedPtr, public_path);
if (info.path_dst_ptr_to_static_ptr == public_path)
return true;
return false;
}
bool __pointer_to_member_type_info::can_catch_nested(
const __shim_type_info* thrown_type) const
{
const __pointer_to_member_type_info* thrown_member_ptr_type =
dynamic_cast<const __pointer_to_member_type_info*>(thrown_type);
if (thrown_member_ptr_type == 0)
return false;
if (~__flags & thrown_member_ptr_type->__flags)
return false;
if (!is_equal(__pointee, thrown_member_ptr_type->__pointee, false))
return false;
if (!is_equal(__context, thrown_member_ptr_type->__context, false))
return false;
return true;
}
#ifdef __clang__
#pragma clang diagnostic pop
#pragma GCC visibility pop
#pragma GCC visibility push(default)
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wmissing-field-initializers"
// __dynamic_cast
// static_ptr: pointer to an object of type static_type; nonnull, and since the
// object is polymorphic, *(void**)static_ptr is a virtual table pointer.
// static_ptr is &v in the expression dynamic_cast<T>(v).
// static_type: static type of the object pointed to by static_ptr.
// dst_type: destination type of the cast (the "T" in "dynamic_cast<T>(v)").
// src2dst_offset: a static hint about the location of the
// source subobject with respect to the complete object;
// special negative values are:
// -1: no hint
// -2: static_type is not a public base of dst_type
// -3: static_type is a multiple public base type but never a
// virtual base type
// otherwise, the static_type type is a unique public nonvirtual
// base type of dst_type at offset src2dst_offset from the
// origin of dst_type.
//
// (dynamic_ptr, dynamic_type) are the run time type of the complete object
// referred to by static_ptr and a pointer to it. These can be found from
// static_ptr for polymorphic types.
// static_type is guaranteed to be a polymorphic type.
//
// (dynamic_ptr, dynamic_type) is the root of a DAG that grows upward. Each
// node of the tree represents a base class/object of its parent (or parents) below.
// Each node is uniquely represented by a pointer to the object, and a pointer
// to a type_info - its type. Different nodes may have the same pointer and
// different nodes may have the same type. But only one node has a specific
// (pointer-value, type) pair. In C++ two objects of the same type can not
// share the same address.
//
// There are two flavors of nodes which have the type dst_type:
// 1. Those that are derived from (below) (static_ptr, static_type).
// 2. Those that are not derived from (below) (static_ptr, static_type).
//
// Invariants of the DAG:
//
// There is at least one path from the root (dynamic_ptr, dynamic_type) to
// the node (static_ptr, static_type). This path may or may not be public.
// There may be more than one such path (some public some not). Such a path may
// or may not go through a node having type dst_type.
//
// No node of type T appears above a node of the same type. That means that
// there is only one node with dynamic_type. And if dynamic_type == dst_type,
// then there is only one dst_type in the DAG.
//
// No node of type dst_type appears above a node of type static_type. Such
// DAG's are possible in C++, but the compiler computes those dynamic_casts at
// compile time, and only calls __dynamic_cast when dst_type lies below
// static_type in the DAG.
//
// dst_type != static_type: The compiler computes the dynamic_cast in this case too.
// dynamic_type != static_type: The compiler computes the dynamic_cast in this case too.
//
// Returns:
//
// If there is exactly one dst_type of flavor 1, and
// If there is a public path from that dst_type to (static_ptr, static_type), or
// If there are 0 dst_types of flavor 2, and there is a public path from
// (dynamic_ptr, dynamic_type) to (static_ptr, static_type) and a public
// path from (dynamic_ptr, dynamic_type) to the one dst_type, then return
// a pointer to that dst_type.
// Else if there are 0 dst_types of flavor 1 and exactly 1 dst_type of flavor 2, and
// if there is a public path from (dynamic_ptr, dynamic_type) to
// (static_ptr, static_type) and a public path from (dynamic_ptr, dynamic_type)
// to the one dst_type, then return a pointer to that one dst_type.
// Else return nullptr.
//
// If dynamic_type == dst_type, then the above algorithm collapses to the
// following cheaper algorithm:
//
// If there is a public path from (dynamic_ptr, dynamic_type) to
// (static_ptr, static_type), then return dynamic_ptr.
// Else return nullptr.
extern "C"
void*
__dynamic_cast(const void* static_ptr,
const __class_type_info* static_type,
const __class_type_info* dst_type,
std::ptrdiff_t src2dst_offset)
{
// Possible future optimization: Take advantage of src2dst_offset
// Currently clang always sets src2dst_offset to -1 (no hint).
// Get (dynamic_ptr, dynamic_type) from static_ptr
void** vtable = *(void***)static_ptr;
ptrdiff_t offset_to_derived = reinterpret_cast<ptrdiff_t>(vtable[-2]);
const void* dynamic_ptr = static_cast<const char*>(static_ptr) + offset_to_derived;
const __class_type_info* dynamic_type = static_cast<const __class_type_info*>(vtable[-1]);
// Initialize answer to nullptr. This will be changed from the search
// results if a non-null answer is found. Regardless, this is what will
// be returned.
const void* dst_ptr = 0;
// Initialize info struct for this search.
__dynamic_cast_info info = {dst_type, static_ptr, static_type, src2dst_offset, 0};
// Find out if we can use a giant short cut in the search
if (is_equal(dynamic_type, dst_type, false))
{
// Using giant short cut. Add that information to info.
info.number_of_dst_type = 1;
// Do the search
dynamic_type->search_above_dst(&info, dynamic_ptr, dynamic_ptr, public_path, false);
#if _LIBCXX_DYNAMIC_FALLBACK
// The following if should always be false because we should definitely
// find (static_ptr, static_type), either on a public or private path
if (info.path_dst_ptr_to_static_ptr == unknown)
{
// We get here only if there is some kind of visibility problem
// in client code.
syslog(LOG_ERR, "dynamic_cast error 1: Both of the following type_info's "
"should have public visibility. At least one of them is hidden. %s"
", %s.\n", static_type->name(), dynamic_type->name());
// Redo the search comparing type_info's using strcmp
info = {dst_type, static_ptr, static_type, src2dst_offset, 0};
info.number_of_dst_type = 1;
dynamic_type->search_above_dst(&info, dynamic_ptr, dynamic_ptr, public_path, true);
}
#endif // _LIBCXX_DYNAMIC_FALLBACK
// Query the search.
if (info.path_dst_ptr_to_static_ptr == public_path)
dst_ptr = dynamic_ptr;
}
else
{
// Not using giant short cut. Do the search
dynamic_type->search_below_dst(&info, dynamic_ptr, public_path, false);
#if _LIBCXX_DYNAMIC_FALLBACK
// The following if should always be false because we should definitely
// find (static_ptr, static_type), either on a public or private path
if (info.path_dst_ptr_to_static_ptr == unknown &&
info.path_dynamic_ptr_to_static_ptr == unknown)
{
syslog(LOG_ERR, "dynamic_cast error 2: One or more of the following type_info's "
" has hidden visibility. They should all have public visibility. "
" %s, %s, %s.\n", static_type->name(), dynamic_type->name(),
dst_type->name());
// Redo the search comparing type_info's using strcmp
info = {dst_type, static_ptr, static_type, src2dst_offset, 0};
dynamic_type->search_below_dst(&info, dynamic_ptr, public_path, true);
}
#endif // _LIBCXX_DYNAMIC_FALLBACK
// Query the search.
switch (info.number_to_static_ptr)
{
case 0:
if (info.number_to_dst_ptr == 1 &&
info.path_dynamic_ptr_to_static_ptr == public_path &&
info.path_dynamic_ptr_to_dst_ptr == public_path)
dst_ptr = info.dst_ptr_not_leading_to_static_ptr;
break;
case 1:
if (info.path_dst_ptr_to_static_ptr == public_path ||
(
info.number_to_dst_ptr == 0 &&
info.path_dynamic_ptr_to_static_ptr == public_path &&
info.path_dynamic_ptr_to_dst_ptr == public_path
)
)
dst_ptr = info.dst_ptr_leading_to_static_ptr;
break;
}
}
return const_cast<void*>(dst_ptr);
}
#pragma clang diagnostic pop
#pragma GCC visibility pop
#pragma GCC visibility push(hidden)
// Call this function when you hit a static_type which is a base (above) a dst_type.
// Let caller know you hit a static_type. But only start recording details if
// this is (static_ptr, static_type) -- the node we are casting from.
// If this is (static_ptr, static_type)
// Record the path (public or not) from the dst_type to here. There may be
// multiple paths from the same dst_type to here, record the "most public" one.
// Record the dst_ptr as pointing to (static_ptr, static_type).
// If more than one (dst_ptr, dst_type) points to (static_ptr, static_type),
// then mark this dyanmic_cast as ambiguous and stop the search.
void
__class_type_info::process_static_type_above_dst(__dynamic_cast_info* info,
const void* dst_ptr,
const void* current_ptr,
int path_below) const
{
// Record that we found a static_type
info->found_any_static_type = true;
if (current_ptr == info->static_ptr)
{
// Record that we found (static_ptr, static_type)
info->found_our_static_ptr = true;
if (info->dst_ptr_leading_to_static_ptr == 0)
{
// First time here
info->dst_ptr_leading_to_static_ptr = dst_ptr;
info->path_dst_ptr_to_static_ptr = path_below;
info->number_to_static_ptr = 1;
// If there is only one dst_type in the entire tree and the path from
// there to here is public then we are done!
if (info->number_of_dst_type == 1 && info->path_dst_ptr_to_static_ptr == public_path)
info->search_done = true;
}
else if (info->dst_ptr_leading_to_static_ptr == dst_ptr)
{
// We've been here before. Update path to "most public"
if (info->path_dst_ptr_to_static_ptr == not_public_path)
info->path_dst_ptr_to_static_ptr = path_below;
// If there is only one dst_type in the entire tree and the path from
// there to here is public then we are done!
if (info->number_of_dst_type == 1 && info->path_dst_ptr_to_static_ptr == public_path)
info->search_done = true;
}
else
{
// We've detected an ambiguous cast from (static_ptr, static_type)
// to a dst_type
info->number_to_static_ptr += 1;
info->search_done = true;
}
}
}
// Call this function when you hit a static_type which is not a base (above) a dst_type.
// If this is (static_ptr, static_type)
// Record the path (public or not) from (dynamic_ptr, dynamic_type) to here. There may be
// multiple paths from (dynamic_ptr, dynamic_type) to here, record the "most public" one.
void
__class_type_info::process_static_type_below_dst(__dynamic_cast_info* info,
const void* current_ptr,
int path_below) const
{
if (current_ptr == info->static_ptr)
{
// Record the most public path from (dynamic_ptr, dynamic_type) to
// (static_ptr, static_type)
if (info->path_dynamic_ptr_to_static_ptr != public_path)
info->path_dynamic_ptr_to_static_ptr = path_below;
}
}
// Call this function when searching below a dst_type node. This function searches
// for a path to (static_ptr, static_type) and for paths to one or more dst_type nodes.
// If it finds a static_type node, there is no need to further search base classes
// above.
// If it finds a dst_type node it should search base classes using search_above_dst
// to find out if this dst_type points to (static_ptr, static_type) or not.
// Either way, the dst_type is recorded as one of two "flavors": one that does
// or does not point to (static_ptr, static_type).
// If this is neither a static_type nor a dst_type node, continue searching
// base classes above.
// All the hoopla surrounding the search code is doing nothing but looking for
// excuses to stop the search prematurely (break out of the for-loop). That is,
// the algorithm below is simply an optimization of this:
// void
// __vmi_class_type_info::search_below_dst(__dynamic_cast_info* info,
// const void* current_ptr,
// int path_below) const
// {
// typedef const __base_class_type_info* Iter;
// if (this == info->static_type)
// process_static_type_below_dst(info, current_ptr, path_below);
// else if (this == info->dst_type)
// {
// // Record the most public access path that got us here
// if (info->path_dynamic_ptr_to_dst_ptr != public_path)
// info->path_dynamic_ptr_to_dst_ptr = path_below;
// bool does_dst_type_point_to_our_static_type = false;
// for (Iter p = __base_info, e= __base_info + __base_count; p < e; ++p)
// {
// p->search_above_dst(info, current_ptr, current_ptr, public_path);
// if (info->found_our_static_ptr)
// does_dst_type_point_to_our_static_type = true;
// // break out early here if you can detect it doesn't matter if you do
// }
// 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;
// }
// }
// else
// {
// // This is not a static_type and not a dst_type.
// for (Iter p = __base_info, e = __base_info + __base_count; p < e; ++p)
// {
// p->search_below_dst(info, current_ptr, public_path);
// // break out early here if you can detect it doesn't matter if you do
// }
// }
// }
void
__vmi_class_type_info::search_below_dst(__dynamic_cast_info* info,
const void* current_ptr,
int path_below,
bool use_strcmp) const
{
typedef const __base_class_type_info* Iter;
if (is_equal(this, info->static_type, use_strcmp))
process_static_type_below_dst(info, current_ptr, path_below);
else if (is_equal(this, info->dst_type, use_strcmp))
{
// We've been here before if we've recorded current_ptr in one of these
// two places:
if (current_ptr == info->dst_ptr_leading_to_static_ptr ||
current_ptr == info->dst_ptr_not_leading_to_static_ptr)
{
// We've seen this node before, and therefore have already searched
// its base classes above.
// Update path to here that is "most public".
if (path_below == public_path)
info->path_dynamic_ptr_to_dst_ptr = public_path;
}
else // We have haven't been here before
{
// 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;
// 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).
// We can stop looking above if:
// 1. We've found a public path to (static_ptr, static_type).
// 2. We've found an ambiguous cast from (static_ptr, static_type) to a dst_type.
// This is detected at the (static_ptr, static_type).
// 3. We can prove that there is no public path to (static_ptr, static_type)
// above here.
const Iter e = __base_info + __base_count;
for (Iter p = __base_info; p < e; ++p)
{
// Zero out found flags
info->found_our_static_ptr = false;
info->found_any_static_type = false;
p->search_above_dst(info, current_ptr, current_ptr, public_path, use_strcmp);
if (info->search_done)
break;
if (info->found_any_static_type)
{
is_dst_type_derived_from_static_type = true;
if (info->found_our_static_ptr)
{
does_dst_type_point_to_our_static_type = true;
// If we found what we're looking for, stop looking above.
if (info->path_dst_ptr_to_static_ptr == public_path)
break;
// We found a private path to (static_ptr, static_type)
// If there is no diamond then there is only one path
// to (static_ptr, static_type) and we just found it.
if (!(__flags & __diamond_shaped_mask))
break;
}
else
{
// If we found a static_type that isn't the one we're looking
// for, and if there are no repeated types above here,
// then stop looking.
if (!(__flags & __non_diamond_repeat_mask))
break;
}
}
}
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
// it if it doesn't derive from static_type.
if (is_dst_type_derived_from_static_type)
info->is_dst_type_derived_from_static_type = yes;
else
info->is_dst_type_derived_from_static_type = no;
}
}
}
else
{
// This is not a static_type and not a dst_type.
const Iter e = __base_info + __base_count;
Iter p = __base_info;
p->search_below_dst(info, current_ptr, path_below, use_strcmp);
if (++p < e)
{
if ((__flags & __diamond_shaped_mask) || info->number_to_static_ptr == 1)
{
// If there are multiple paths to a base above from here, or if
// a dst_type pointing to (static_ptr, static_type) has been found,
// then there is no way to break out of this loop early unless
// something below detects the search is done.
do
{
if (info->search_done)
break;
p->search_below_dst(info, current_ptr, path_below, use_strcmp);
} while (++p < e);
}
else if (__flags & __non_diamond_repeat_mask)
{
// There are not multiple paths to any base class from here and a
// dst_type pointing to (static_ptr, static_type) has not yet been
// found.
do
{
if (info->search_done)
break;
// If we just found a dst_type with a public path to (static_ptr, static_type),
// then the only reason to continue the search is to make sure
// no other dst_type points to (static_ptr, static_type).
// If !diamond, then we don't need to search here.
if (info->number_to_static_ptr == 1 &&
info->path_dst_ptr_to_static_ptr == public_path)
break;
p->search_below_dst(info, current_ptr, path_below, use_strcmp);
} while (++p < e);
}
else
{
// There are no repeated types above this node.
// There are no nodes with multiple parents above this node.
// no dst_type has been found to (static_ptr, static_type)
do
{
if (info->search_done)
break;
// If we just found a dst_type with a public path to (static_ptr, static_type),
// then the only reason to continue the search is to make sure sure
// no other dst_type points to (static_ptr, static_type).
// If !diamond, then we don't need to search here.
// if we just found a dst_type with a private path to (static_ptr, static_type),
// then we're only looking for a public path to (static_ptr, static_type)
// and to check for other dst_types.
// If !diamond & !repeat, then there is not a pointer to (static_ptr, static_type)
// and not a dst_type under here.
if (info->number_to_static_ptr == 1)
break;
p->search_below_dst(info, current_ptr, path_below, use_strcmp);
} while (++p < e);
}
}
}
}
// This is the same algorithm as __vmi_class_type_info::search_below_dst but
// simplified to the case that there is only a single base class.
void
__si_class_type_info::search_below_dst(__dynamic_cast_info* info,
const void* current_ptr,
int path_below,
bool use_strcmp) const
{
if (is_equal(this, info->static_type, use_strcmp))
process_static_type_below_dst(info, current_ptr, path_below);
else if (is_equal(this, info->dst_type, use_strcmp))
{
// We've been here before if we've recorded current_ptr in one of these
// two places:
if (current_ptr == info->dst_ptr_leading_to_static_ptr ||
current_ptr == info->dst_ptr_not_leading_to_static_ptr)
{
// We've seen this node before, and therefore have already searched
// its base classes above.
// Update path to here that is "most public".
if (path_below == public_path)
info->path_dynamic_ptr_to_dst_ptr = public_path;
}
else // We have haven't been here before
{
// 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;
// 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;
__base_type->search_above_dst(info, current_ptr, current_ptr, public_path, use_strcmp);
if (info->found_any_static_type)
{
is_dst_type_derived_from_static_type = true;
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
// it if it doesn't derive from static_type.
if (is_dst_type_derived_from_static_type)
info->is_dst_type_derived_from_static_type = yes;
else
info->is_dst_type_derived_from_static_type = no;
}
}
}
else
{
// This is not a static_type and not a dst_type
__base_type->search_below_dst(info, current_ptr, path_below, use_strcmp);
}
}
// This is the same algorithm as __vmi_class_type_info::search_below_dst but
// simplified to the case that there is no base class.
void
__class_type_info::search_below_dst(__dynamic_cast_info* info,
const void* current_ptr,
int path_below,
bool use_strcmp) const
{
if (is_equal(this, info->static_type, use_strcmp))
process_static_type_below_dst(info, current_ptr, path_below);
else if (is_equal(this, info->dst_type, use_strcmp))
{
// We've been here before if we've recorded current_ptr in one of these
// two places:
if (current_ptr == info->dst_ptr_leading_to_static_ptr ||
current_ptr == info->dst_ptr_not_leading_to_static_ptr)
{
// We've seen this node before, and therefore have already searched
// its base classes above.
// Update path to here that is "most public".
if (path_below == public_path)
info->path_dynamic_ptr_to_dst_ptr = public_path;
}
else // We have haven't been here before
{
// 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;
// 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;
// We found that dst_type does not derive from static_type
info->is_dst_type_derived_from_static_type = no;
}
}
}
// Call this function when searching above a dst_type node. This function searches
// for a public path to (static_ptr, static_type).
// This function is guaranteed not to find a node of type dst_type.
// Theoretically this is a very simple function which just stops if it finds a
// static_type node: All the hoopla surrounding the search code is doing
// nothing but looking for excuses to stop the search prematurely (break out of
// the for-loop). That is, the algorithm below is simply an optimization of this:
// void
// __vmi_class_type_info::search_above_dst(__dynamic_cast_info* info,
// const void* dst_ptr,
// const void* current_ptr,
// int path_below) const
// {
// if (this == info->static_type)
// process_static_type_above_dst(info, dst_ptr, current_ptr, path_below);
// else
// {
// typedef const __base_class_type_info* Iter;
// // This is not a static_type and not a dst_type
// for (Iter p = __base_info, e = __base_info + __base_count; p < e; ++p)
// {
// p->search_above_dst(info, dst_ptr, current_ptr, public_path);
// // break out early here if you can detect it doesn't matter if you do
// }
// }
// }
void
__vmi_class_type_info::search_above_dst(__dynamic_cast_info* info,
const void* dst_ptr,
const void* current_ptr,
int path_below,
bool use_strcmp) const
{
if (is_equal(this, info->static_type, use_strcmp))
process_static_type_above_dst(info, dst_ptr, current_ptr, path_below);
else
{
typedef const __base_class_type_info* Iter;
// This is not a static_type and not a dst_type
// Save flags so they can be restored when returning to nodes below.
bool found_our_static_ptr = info->found_our_static_ptr;
bool found_any_static_type = info->found_any_static_type;
// We've found a dst_type below with a path to here. If the path
// to here is not public, there may be another path to here that
// is public. So we have to assume that the path to here is public.
// We can stop looking above if:
// 1. We've found a public path to (static_ptr, static_type).
// 2. We've found an ambiguous cast from (static_ptr, static_type) to a dst_type.
// This is detected at the (static_ptr, static_type).
// 3. We can prove that there is no public path to (static_ptr, static_type)
// above here.
const Iter e = __base_info + __base_count;
Iter p = __base_info;
// Zero out found flags
info->found_our_static_ptr = false;
info->found_any_static_type = false;
p->search_above_dst(info, dst_ptr, current_ptr, path_below, use_strcmp);
if (++p < e)
{
do
{
if (info->search_done)
break;
if (info->found_our_static_ptr)
{
// If we found what we're looking for, stop looking above.
if (info->path_dst_ptr_to_static_ptr == public_path)
break;
// We found a private path to (static_ptr, static_type)
// If there is no diamond then there is only one path
// to (static_ptr, static_type) from here and we just found it.
if (!(__flags & __diamond_shaped_mask))
break;
}
else if (info->found_any_static_type)
{
// If we found a static_type that isn't the one we're looking
// for, and if there are no repeated types above here,
// then stop looking.
if (!(__flags & __non_diamond_repeat_mask))
break;
}
// Zero out found flags
info->found_our_static_ptr = false;
info->found_any_static_type = false;
p->search_above_dst(info, dst_ptr, current_ptr, path_below, use_strcmp);
} while (++p < e);
}
// Restore flags
info->found_our_static_ptr = found_our_static_ptr;
info->found_any_static_type = found_any_static_type;
}
}
// This is the same algorithm as __vmi_class_type_info::search_above_dst but
// simplified to the case that there is only a single base class.
void
__si_class_type_info::search_above_dst(__dynamic_cast_info* info,
const void* dst_ptr,
const void* current_ptr,
int path_below,
bool use_strcmp) const
{
if (is_equal(this, info->static_type, use_strcmp))
process_static_type_above_dst(info, dst_ptr, current_ptr, path_below);
else
__base_type->search_above_dst(info, dst_ptr, current_ptr, path_below, use_strcmp);
}
// This is the same algorithm as __vmi_class_type_info::search_above_dst but
// simplified to the case that there is no base class.
void
__class_type_info::search_above_dst(__dynamic_cast_info* info,
const void* dst_ptr,
const void* current_ptr,
int path_below,
bool use_strcmp) const
{
if (is_equal(this, info->static_type, use_strcmp))
process_static_type_above_dst(info, dst_ptr, current_ptr, path_below);
}
// The search functions for __base_class_type_info are simply convenience
// functions for adjusting the current_ptr and path_below as the search is
// passed up to the base class node.
void
__base_class_type_info::search_above_dst(__dynamic_cast_info* info,
const void* dst_ptr,
const void* current_ptr,
int path_below,
bool use_strcmp) const
{
ptrdiff_t offset_to_base = __offset_flags >> __offset_shift;
if (__offset_flags & __virtual_mask)
{
const char* vtable = *static_cast<const char*const*>(current_ptr);
offset_to_base = *reinterpret_cast<const ptrdiff_t*>(vtable + offset_to_base);
}
__base_type->search_above_dst(info, dst_ptr,
static_cast<const char*>(current_ptr) + offset_to_base,
(__offset_flags & __public_mask) ?
path_below :
not_public_path,
use_strcmp);
}
void
__base_class_type_info::search_below_dst(__dynamic_cast_info* info,
const void* current_ptr,
int path_below,
bool use_strcmp) const
{
ptrdiff_t offset_to_base = __offset_flags >> __offset_shift;
if (__offset_flags & __virtual_mask)
{
const char* vtable = *static_cast<const char*const*>(current_ptr);
offset_to_base = *reinterpret_cast<const ptrdiff_t*>(vtable + offset_to_base);
}
__base_type->search_below_dst(info,
static_cast<const char*>(current_ptr) + offset_to_base,
(__offset_flags & __public_mask) ?
path_below :
not_public_path,
use_strcmp);
}
#pragma GCC visibility pop
} // __cxxabiv1