// The current instruction of "c" is a jump; one of its offset starts
// at "offset" and is a short if "isShort" is "TRUE",
// and an integer otherwise. If the jump crosses "breakPC", change
// the span of the jump by "delta".
void Relocator::change_jump(int bci, int offset, bool is_short, int break_bci, int delta) {
int bci_delta = (is_short) ? short_at(offset) : int_at(offset);
int targ = bci + bci_delta;
if ((bci <= break_bci && targ > break_bci) ||
(bci > break_bci && targ <= break_bci)) {
int new_delta;
if (bci_delta > 0)
new_delta = bci_delta + delta;
else
new_delta = bci_delta - delta;
if (is_short && ((new_delta > MAX_SHORT) || new_delta < MIN_SHORT)) {
push_jump_widen(bci, delta, new_delta);
} else if (is_short) {
short_at_put(offset, new_delta);
} else {
int_at_put(offset, new_delta);
}
}
}
// 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;
}
void set_register_at(int index, Assembler::Register reg) { int_at_put(index, (jint)reg); }
void set_top_of_stack(int index) { int_at_put(0, index); }