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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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#ifndef SHARE_VM_PRIMS_METHODCOMPARATOR_HPP
#define SHARE_VM_PRIMS_METHODCOMPARATOR_HPP
#include "interpreter/bytecodeStream.hpp"
#include "oops/constantPoolOop.hpp"
#include "oops/methodOop.hpp"
class BciMap;
// methodComparator provides an interface for determining if methods of
// different versions of classes are equivalent or switchable
class MethodComparator {
private:
static BytecodeStream *_s_old, *_s_new;
static constantPoolOop _old_cp, _new_cp;
static BciMap *_bci_map;
static bool _switchable_test;
static GrowableArray<int> *_fwd_jmps;
static bool args_same(Bytecodes::Code c_old, Bytecodes::Code c_new);
static bool pool_constants_same(int cpi_old, int cpi_new);
static int check_stack_and_locals_size(methodOop old_method, methodOop new_method);
public:
// Check if the new method is equivalent to the old one modulo constant pool (EMCP).
// Intuitive definition: two versions of the same method are EMCP, if they don't differ
// on the source code level. Practically, we check whether the only difference between
// method versions is some constantpool indices embedded into the bytecodes, and whether
// these indices eventually point to the same constants for both method versions.
static bool methods_EMCP(methodOop old_method, methodOop new_method);
static bool methods_switchable(methodOop old_method, methodOop new_method, BciMap &bci_map);
};
// ByteCode Index Map. For two versions of the same method, where the new version may contain
// fragments not found in the old version, provides a mapping from an index of a bytecode in
// the old method to the index of the same bytecode in the new method.
class BciMap {
private:
int *_old_bci, *_new_st_bci, *_new_end_bci;
int _cur_size, _cur_pos;
int _pos;
public:
BciMap() {
_cur_size = 50;
_old_bci = (int*) malloc(sizeof(int) * _cur_size);
_new_st_bci = (int*) malloc(sizeof(int) * _cur_size);
_new_end_bci = (int*) malloc(sizeof(int) * _cur_size);
_cur_pos = 0;
}
~BciMap() {
free(_old_bci);
free(_new_st_bci);
free(_new_end_bci);
}
// Store the position of an added fragment, e.g.
//
// |<- old_bci
// -----------------------------------------
// Old method |invokevirtual 5|aload 1|...
// -----------------------------------------
//
// |<- new_st_bci |<- new_end_bci
// --------------------------------------------------------------------
// New method |invokevirual 5|aload 2|invokevirtual 6|aload 1|...
// --------------------------------------------------------------------
// ^^^^^^^^^^^^^^^^^^^^^^^^
// Added fragment
void store_fragment_location(int old_bci, int new_st_bci, int new_end_bci) {
if (_cur_pos == _cur_size) {
_cur_size += 10;
_old_bci = (int*) realloc(_old_bci, sizeof(int) * _cur_size);
_new_st_bci = (int*) realloc(_new_st_bci, sizeof(int) * _cur_size);
_new_end_bci = (int*) realloc(_new_end_bci, sizeof(int) * _cur_size);
}
_old_bci[_cur_pos] = old_bci;
_new_st_bci[_cur_pos] = new_st_bci;
_new_end_bci[_cur_pos] = new_end_bci;
_cur_pos++;
}
int new_bci_for_old(int old_bci) {
if (_cur_pos == 0 || old_bci < _old_bci[0]) return old_bci;
_pos = 1;
while (_pos < _cur_pos && old_bci >= _old_bci[_pos])
_pos++;
return _new_end_bci[_pos-1] + (old_bci - _old_bci[_pos-1]);
}
// Test if two indexes - one in the old method and another in the new one - correspond
// to the same bytecode
bool old_and_new_locations_same(int old_dest_bci, int new_dest_bci) {
if (new_bci_for_old(old_dest_bci) == new_dest_bci)
return true;
else if (_old_bci[_pos-1] == old_dest_bci)
return (new_dest_bci == _new_st_bci[_pos-1]);
else return false;
}
};
#endif // SHARE_VM_PRIMS_METHODCOMPARATOR_HPP