// We need a special instruction size method, since lookupswitches and tableswitches might not be
// properly alligned during relocation
int Relocator::rc_instr_len(int bci) {
Bytecodes::Code bc= code_at(bci);
switch (bc) {
// In the case of switch instructions, see if we have the original
// padding recorded.
case Bytecodes::_tableswitch:
case Bytecodes::_lookupswitch:
case Bytecodes::_fast_linearswitch:
case Bytecodes::_fast_binaryswitch:
{
int pad = get_orig_switch_pad(bci, is_opcode_lookupswitch(bc));
if (pad == -1) {
return instruction_length_at(bci);
}
// Otherwise, depends on the switch type.
switch (bc) {
case Bytecodes::_tableswitch: {
int lo = int_at(bci + 1 + pad + 4 * 1);
int hi = int_at(bci + 1 + pad + 4 * 2);
int n = hi - lo + 1;
return 1 + pad + 4*(3 + n);
}
case Bytecodes::_lookupswitch:
case Bytecodes::_fast_linearswitch:
case Bytecodes::_fast_binaryswitch: {
int npairs = int_at(bci + 1 + pad + 4 * 1);
return 1 + pad + 4*(2 + 2*npairs);
}
default:
ShouldNotReachHere();
}
}
}
return instruction_length_at(bci);
}
int Bytecodes::special_length_at(address bcp) {
Code code = code_at(bcp);
switch (code) {
case _wide:
return wide_length_for(cast(*(bcp + 1)));
case _tableswitch:
{ address aligned_bcp = (address)round_to((intptr_t)bcp + 1, jintSize);
jlong lo = (jint)Bytes::get_Java_u4(aligned_bcp + 1*jintSize);
jlong hi = (jint)Bytes::get_Java_u4(aligned_bcp + 2*jintSize);
jlong len = (aligned_bcp - bcp) + (3 + hi - lo + 1)*jintSize;
// only return len if it can be represented as a positive int;
// return -1 otherwise
return (len > 0 && len == (int)len) ? len : -1;
}
case _lookupswitch: // fall through
case _fast_binaryswitch: // fall through
case _fast_linearswitch:
{ address aligned_bcp = (address)round_to((intptr_t)bcp + 1, jintSize);
jlong npairs = (jint)Bytes::get_Java_u4(aligned_bcp + jintSize);
jlong len = (aligned_bcp - bcp) + (2 + 2*npairs)*jintSize;
// only return len if it can be represented as a positive int;
// return -1 otherwise
return (len > 0 && len == (int)len) ? len : -1;
}
}
return 0;
}
int Bytecodes::special_length_at(address bcp, address end) {
Code code = code_at(bcp);
switch (code) {
case _wide:
if (end != NULL && bcp + 1 >= end) {
return -1; // don't read past end of code buffer
}
return wide_length_for(cast(*(bcp + 1)));
case _tableswitch:
{ address aligned_bcp = (address)round_to((intptr_t)bcp + 1, jintSize);
if (end != NULL && aligned_bcp + 3*jintSize >= end) {
return -1; // don't read past end of code buffer
}
jlong lo = (jint)Bytes::get_Java_u4(aligned_bcp + 1*jintSize);
jlong hi = (jint)Bytes::get_Java_u4(aligned_bcp + 2*jintSize);
jlong len = (aligned_bcp - bcp) + (3 + hi - lo + 1)*jintSize;
// only return len if it can be represented as a positive int;
// return -1 otherwise
return (len > 0 && len == (int)len) ? len : -1;
}
case _lookupswitch: // fall through
case _fast_binaryswitch: // fall through
case _fast_linearswitch:
{ address aligned_bcp = (address)round_to((intptr_t)bcp + 1, jintSize);
if (end != NULL && aligned_bcp + 2*jintSize >= end) {
return -1; // don't read past end of code buffer
}
jlong npairs = (jint)Bytes::get_Java_u4(aligned_bcp + jintSize);
jlong len = (aligned_bcp - bcp) + (2 + 2*npairs)*jintSize;
// only return len if it can be represented as a positive int;
// return -1 otherwise
return (len > 0 && len == (int)len) ? len : -1;
}
}
// Note: Length functions must return <=0 for invalid bytecodes.
return 0;
}
static int length_at (address bcp) {
int l = length_for(code_at(bcp));
return l > 0 ? l : special_length_at(bcp);
}
static Code java_code_at(address bcp, methodOop method = NULL) {
return java_code(code_at(bcp, method));
}
// handle jump_widen instruction. Called be ChangeJumpWiden class
bool Relocator::handle_jump_widen(int bci, int delta) {
int ilen = rc_instr_len(bci);
Bytecodes::Code bc = code_at(bci);
switch (bc) {
case Bytecodes::_ifeq:
case Bytecodes::_ifne:
case Bytecodes::_iflt:
case Bytecodes::_ifge:
case Bytecodes::_ifgt:
case Bytecodes::_ifle:
case Bytecodes::_if_icmpeq:
case Bytecodes::_if_icmpne:
case Bytecodes::_if_icmplt:
case Bytecodes::_if_icmpge:
case Bytecodes::_if_icmpgt:
case Bytecodes::_if_icmple:
case Bytecodes::_if_acmpeq:
case Bytecodes::_if_acmpne:
case Bytecodes::_ifnull:
case Bytecodes::_ifnonnull: {
const int goto_length = Bytecodes::length_for(Bytecodes::_goto);
// If 'if' points to the next bytecode after goto, it's already handled.
// it shouldn't be.
assert (short_at(bci+1) != ilen+goto_length, "if relocation already handled");
assert(ilen == 3, "check length");
// Convert to 0 if <cond> goto 6
// 3 _goto 11
// 6 _goto_w <wide delta offset>
// 11 <else code>
const int goto_w_length = Bytecodes::length_for(Bytecodes::_goto_w);
const int add_bci = goto_length + goto_w_length;
if (!relocate_code(bci, 3, /*delta*/add_bci)) return false;
// if bytecode points to goto_w instruction
short_at_put(bci + 1, ilen + goto_length);
int cbci = bci + ilen;
// goto around
code_at_put(cbci, Bytecodes::_goto);
short_at_put(cbci + 1, add_bci);
// goto_w <wide delta>
cbci = cbci + goto_length;
code_at_put(cbci, Bytecodes::_goto_w);
if (delta > 0) {
delta += 2; // goto_w is 2 bytes more than "if" code
} else {
delta -= ilen+goto_length; // branch starts at goto_w offset
}
int_at_put(cbci + 1, delta);
break;
}
case Bytecodes::_goto:
case Bytecodes::_jsr:
assert(ilen == 3, "check length");
if (!relocate_code(bci, 3, 2)) return false;
if (bc == Bytecodes::_goto)
code_at_put(bci, Bytecodes::_goto_w);
else
code_at_put(bci, Bytecodes::_jsr_w);
// If it's a forward jump, add 2 for the widening.
if (delta > 0) delta += 2;
int_at_put(bci + 1, delta);
break;
default: ShouldNotReachHere();
}
return true;
}
// Changes all jumps crossing "break_bci" by "delta". May enqueue things
// on "rc->changes"
void Relocator::change_jumps(int break_bci, int delta) {
int bci = 0;
Bytecodes::Code bc;
// Now, adjust any affected instructions.
while (bci < code_length()) {
switch (bc= code_at(bci)) {
case Bytecodes::_ifeq:
case Bytecodes::_ifne:
case Bytecodes::_iflt:
case Bytecodes::_ifge:
case Bytecodes::_ifgt:
case Bytecodes::_ifle:
case Bytecodes::_if_icmpeq:
case Bytecodes::_if_icmpne:
case Bytecodes::_if_icmplt:
case Bytecodes::_if_icmpge:
case Bytecodes::_if_icmpgt:
case Bytecodes::_if_icmple:
case Bytecodes::_if_acmpeq:
case Bytecodes::_if_acmpne:
case Bytecodes::_ifnull:
case Bytecodes::_ifnonnull:
case Bytecodes::_goto:
case Bytecodes::_jsr:
change_jump(bci, bci+1, true, break_bci, delta);
break;
case Bytecodes::_goto_w:
case Bytecodes::_jsr_w:
change_jump(bci, bci+1, false, break_bci, delta);
break;
case Bytecodes::_tableswitch:
case Bytecodes::_lookupswitch:
case Bytecodes::_fast_linearswitch:
case Bytecodes::_fast_binaryswitch: {
int recPad = get_orig_switch_pad(bci, (bc != Bytecodes::_tableswitch));
int oldPad = (recPad != -1) ? recPad : align(bci+1) - (bci+1);
if (bci > break_bci) {
int new_bci = bci + delta;
int newPad = align(new_bci+1) - (new_bci+1);
// Do we need to check the padding?
if (newPad != oldPad) {
if (recPad == -1) {
_changes->push(new ChangeSwitchPad(bci, oldPad, (bc != Bytecodes::_tableswitch)));
}
}
}
// Then the rest, which depend on the kind of switch.
switch (bc) {
case Bytecodes::_tableswitch: {
change_jump(bci, bci +1 + oldPad, false, break_bci, delta);
// We cannot use the Bytecode_tableswitch abstraction, since the padding might not be correct.
int lo = int_at(bci + 1 + oldPad + 4 * 1);
int hi = int_at(bci + 1 + oldPad + 4 * 2);
int n = hi - lo + 1;
for (int k = 0; k < n; k++) {
change_jump(bci, bci +1 + oldPad + 4*(k+3), false, break_bci, delta);
}
// Special next-bci calculation here...
bci += 1 + oldPad + (n+3)*4;
continue;
}
case Bytecodes::_lookupswitch:
case Bytecodes::_fast_linearswitch:
case Bytecodes::_fast_binaryswitch: {
change_jump(bci, bci +1 + oldPad, false, break_bci, delta);
// We cannot use the Bytecode_lookupswitch abstraction, since the padding might not be correct.
int npairs = int_at(bci + 1 + oldPad + 4 * 1);
for (int k = 0; k < npairs; k++) {
change_jump(bci, bci + 1 + oldPad + 4*(2 + 2*k + 1), false, break_bci, delta);
}
/* Special next-bci calculation here... */
bci += 1 + oldPad + (2 + (npairs*2))*4;
continue;
}
default:
ShouldNotReachHere();
}
}
default:
break;
}
bci += rc_instr_len(bci);
}
}
Bytecodes::Code Bytecodes::code_at(Method* method, int bci) {
return code_at(method, method->bcp_from(bci));
}
Bytecodes::Code Bytecodes::code_at(methodOop method, int bci) {
return code_at(method->bcp_from(bci), method);
}