ciMethodBlocks::ciMethodBlocks(Arena *arena, ciMethod *meth): _method(meth),
_arena(arena), _num_blocks(0), _code_size(meth->code_size()) {
int block_estimate = _code_size / 8;
_blocks = new(_arena) GrowableArray<ciBlock *>(block_estimate);
int b2bsize = _code_size * sizeof(ciBlock **);
_bci_to_block = (ciBlock **) arena->Amalloc(b2bsize);
Copy::zero_to_words((HeapWord*) _bci_to_block, b2bsize / sizeof(HeapWord));
// create initial block covering the entire method
ciBlock *b = new(arena) ciBlock(_method, _num_blocks++, 0);
_blocks->append(b);
_bci_to_block[0] = b;
// create blocks for exception handlers
if (meth->has_exception_handlers()) {
for(ciExceptionHandlerStream str(meth); !str.is_done(); str.next()) {
ciExceptionHandler* handler = str.handler();
ciBlock *eb = make_block_at(handler->handler_bci());
//
// Several exception handlers can have the same handler_bci:
//
// try {
// if (a.foo(b) < 0) {
// return a.error();
// }
// return CoderResult.UNDERFLOW;
// } finally {
// a.position(b);
// }
//
// The try block above is divided into 2 exception blocks
// separated by 'areturn' bci.
//
int ex_start = handler->start();
int ex_end = handler->limit();
// ensure a block at the start of exception range and start of following code
(void) make_block_at(ex_start);
if (ex_end < _code_size)
(void) make_block_at(ex_end);
if (eb->is_handler()) {
// Extend old handler exception range to cover additional range.
int old_ex_start = eb->ex_start_bci();
int old_ex_end = eb->ex_limit_bci();
if (ex_start > old_ex_start)
ex_start = old_ex_start;
if (ex_end < old_ex_end)
ex_end = old_ex_end;
eb->clear_exception_handler(); // Reset exception information
}
eb->set_exception_range(ex_start, ex_end);
}
}
// scan the bytecodes and identify blocks
do_analysis();
// mark blocks that have exception handlers
if (meth->has_exception_handlers()) {
for(ciExceptionHandlerStream str(meth); !str.is_done(); str.next()) {
ciExceptionHandler* handler = str.handler();
int ex_start = handler->start();
int ex_end = handler->limit();
int bci = ex_start;
while (bci < ex_end) {
ciBlock *b = block_containing(bci);
b->set_has_handler();
bci = b->limit_bci();
}
}
}
}
void MethodLiveness::init_basic_blocks() {
bool bailout = false;
int method_len = method()->code_size();
// Create an array to store the bci->BasicBlock mapping.
_block_map = new (arena()) GrowableArray<BasicBlock*>(arena(), method_len, method_len, NULL);
_block_list = new (arena()) GrowableArray<BasicBlock*>(arena(), 128, 0, NULL);
// Used for patching up jsr/ret control flow.
GrowableArray<BasicBlock*>* jsr_exit_list = new GrowableArray<BasicBlock*>(5);
GrowableArray<BasicBlock*>* ret_list = new GrowableArray<BasicBlock*>(5);
// Make blocks begin at all exception handling instructions.
{
ciExceptionHandlerStream handlers(method());
for (; !handlers.is_done(); handlers.next()) {
ciExceptionHandler* handler = handlers.handler();
int handler_bci = handler->handler_bci();
make_block_at(handler_bci, NULL);
}
}
BasicBlock *current_block = NULL;
ciByteCodeStream bytes(method());
Bytecodes::Code code;
while ((code = bytes.next()) != ciByteCodeStream::EOBC && !bailout) {
int bci = bytes.cur_bci();
// Should we start a new block here?
BasicBlock *other = _block_map->at(bci);
if (other == NULL) {
// This bci has not yet been marked as the start of
// a new basic block. If current_block is NULL, then
// we are beginning a new block. Otherwise, we continue
// with the old block.
if (current_block == NULL) {
// Make a new block with no predecessors.
current_block = make_block_at(bci, NULL);
}
// Mark this index as belonging to the current block.
_block_map->at_put(bci, current_block);
} else {
// This bci has been marked as the start of a new basic
// block.
if (current_block != NULL) {
other->add_normal_predecessor(current_block);
current_block->set_limit_bci(bci);
}
current_block = other;
}
// Now we need to interpret the instruction's effect
// on control flow.
switch (code) {
assert (current_block != NULL, "we must have a current block");
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:
// Two way branch. Make a new block at each destination.
make_block_at(bytes.next_bci(), current_block);
make_block_at(bytes.get_dest(), current_block);
current_block->set_limit_bci(bytes.next_bci());
current_block = NULL;
break;
case Bytecodes::_goto:
make_block_at(bytes.get_dest(), current_block);
current_block->set_limit_bci(bytes.next_bci());
current_block = NULL;
break;
case Bytecodes::_goto_w:
make_block_at(bytes.get_far_dest(), current_block);
current_block->set_limit_bci(bytes.next_bci());
current_block = NULL;
break;
case Bytecodes::_tableswitch:
{
Bytecode_tableswitch *tableswitch =
Bytecode_tableswitch_at(bytes.cur_bcp());
int len = tableswitch->length();
make_block_at(bci + tableswitch->default_offset(), current_block);
while (--len >= 0) {
make_block_at(bci + tableswitch->dest_offset_at(len),
current_block);
}
current_block->set_limit_bci(bytes.next_bci());
current_block = NULL;
break;
}
// Some synthetic opcodes here
case Bytecodes::_fast_linearswitch:
case Bytecodes::_fast_binaryswitch:
case Bytecodes::_lookupswitch:
{
Bytecode_lookupswitch *lookupswitch =
Bytecode_lookupswitch_at(bytes.cur_bcp());
int npairs = lookupswitch->number_of_pairs();
make_block_at(bci + lookupswitch->default_offset(), current_block);
while(--npairs >= 0) {
LookupswitchPair *pair = lookupswitch->pair_at(npairs);
make_block_at(bci + pair->offset(), current_block);
}
current_block->set_limit_bci(bytes.next_bci());
current_block = NULL;
break;
}
case Bytecodes::_jsr:
{
assert(bytes.is_wide()==false, "sanity check");
make_block_at(bytes.get_dest(), current_block);
BasicBlock *jsrExit = make_block_at(bci + 3, NULL);
jsr_exit_list->append(jsrExit);
current_block->set_limit_bci(bytes.next_bci());
current_block = NULL;
break;
}
case Bytecodes::_jsr_w:
{
make_block_at(bytes.get_far_dest(), current_block);
BasicBlock *jsrExit = make_block_at(bci + 5, NULL);
jsr_exit_list->append(jsrExit);
current_block->set_limit_bci(bytes.next_bci());
current_block = NULL;
break;
}
case Bytecodes::_wide:
assert(false, "wide opcodes should not be seen here");
break;
case Bytecodes::_athrow:
case Bytecodes::_ireturn:
case Bytecodes::_lreturn:
case Bytecodes::_freturn:
case Bytecodes::_dreturn:
case Bytecodes::_areturn:
case Bytecodes::_return:
// We are done with the current block. These opcodes are
// not the normal predecessors of any other opcodes.
current_block->set_limit_bci(bytes.next_bci());
current_block = NULL;
break;
case Bytecodes::_ret:
// We will patch up jsr/rets in a subsequent pass.
ret_list->append(current_block);
current_block->set_limit_bci(bytes.next_bci());
current_block = NULL;
break;
case Bytecodes::_breakpoint:
// Bail out of there are breakpoints in here.
bailout = true;
break;
default:
// Do nothing.
break;
}
}
if (bailout) {
_block_list->clear();
_block_map = NULL; // do not use this field now!
return;
}
// Patch up the jsr/ret's. We conservatively assume that any ret
// can return to any jsr site.
int ret_list_len = ret_list->length();
int jsr_exit_list_len = jsr_exit_list->length();
if (ret_list_len > 0 && jsr_exit_list_len > 0) {
for (int i = jsr_exit_list_len - 1; i >= 0; i--) {
BasicBlock *jsrExit = jsr_exit_list->at(i);
for (int i = ret_list_len - 1; i >= 0; i--) {
jsrExit->add_normal_predecessor(ret_list->at(i));
}
}
}
// Compute exception edges.
for (int b=_block_list->length()-1; b >= 0; b--) {
BasicBlock *block = _block_list->at(b);
int block_start = block->start_bci();
int block_limit = block->limit_bci();
ciExceptionHandlerStream handlers(method());
for (; !handlers.is_done(); handlers.next()) {
ciExceptionHandler* handler = handlers.handler();
int start = handler->start();
int limit = handler->limit();
int handler_bci = handler->handler_bci();
int intersect_start = MAX2(block_start, start);
int intersect_limit = MIN2(block_limit, limit);
if (intersect_start < intersect_limit) {
// The catch range has a nonempty intersection with this
// basic block. That means this basic block can be an
// exceptional predecessor.
_block_map->at(handler_bci)->add_exception_predecessor(block);
if (handler->is_catch_all()) {
// This is a catch-all block.
if (intersect_start == block_start && intersect_limit == block_limit) {
// The basic block is entirely contained in this catch-all block.
// Skip the rest of the exception handlers -- they can never be
// reached in execution.
break;
}
}
}
}
}
}
void ciMethodBlocks::do_analysis() {
ciBytecodeStream s(_method);
ciBlock *cur_block = block_containing(0);
int limit_bci = _method->code_size();
while (s.next() != ciBytecodeStream::EOBC()) {
int bci = s.cur_bci();
// Determine if a new block has been made at the current bci. If
// this block differs from our current range, switch to the new
// one and end the old one.
assert(cur_block != NULL, "must always have a current block");
ciBlock *new_block = block_containing(bci);
if (new_block == NULL || new_block == cur_block) {
// We have not marked this bci as the start of a new block.
// Keep interpreting the current_range.
_bci_to_block[bci] = cur_block;
} else {
cur_block->set_limit_bci(bci);
cur_block = new_block;
}
switch (s.cur_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 :
{
cur_block->set_control_bci(bci);
ciBlock *fall_through = make_block_at(s.next_bci());
int dest_bci = s.get_dest();
ciBlock *dest = make_block_at(dest_bci);
break;
}
case Bytecodes::_goto :
{
cur_block->set_control_bci(bci);
if (s.next_bci() < limit_bci) {
(void) make_block_at(s.next_bci());
}
int dest_bci = s.get_dest();
ciBlock *dest = make_block_at(dest_bci);
break;
}
case Bytecodes::_jsr :
{
cur_block->set_control_bci(bci);
ciBlock *ret = make_block_at(s.next_bci());
int dest_bci = s.get_dest();
ciBlock *dest = make_block_at(dest_bci);
break;
}
case Bytecodes::_tableswitch :
{
cur_block->set_control_bci(bci);
Bytecode_tableswitch* switch_ = Bytecode_tableswitch_at(s.cur_bcp());
int len = switch_->length();
ciBlock *dest;
int dest_bci;
for (int i = 0; i < len; i++) {
dest_bci = s.cur_bci() + switch_->dest_offset_at(i);
dest = make_block_at(dest_bci);
}
dest_bci = s.cur_bci() + switch_->default_offset();
make_block_at(dest_bci);
if (s.next_bci() < limit_bci) {
dest = make_block_at(s.next_bci());
}
}
break;
case Bytecodes::_lookupswitch:
{
cur_block->set_control_bci(bci);
Bytecode_lookupswitch* switch_ = Bytecode_lookupswitch_at(s.cur_bcp());
int len = switch_->number_of_pairs();
ciBlock *dest;
int dest_bci;
for (int i = 0; i < len; i++) {
dest_bci = s.cur_bci() + switch_->pair_at(i)->offset();
dest = make_block_at(dest_bci);
}
dest_bci = s.cur_bci() + switch_->default_offset();
dest = make_block_at(dest_bci);
if (s.next_bci() < limit_bci) {
dest = make_block_at(s.next_bci());
}
}
break;
case Bytecodes::_goto_w :
{
cur_block->set_control_bci(bci);
if (s.next_bci() < limit_bci) {
(void) make_block_at(s.next_bci());
}
int dest_bci = s.get_far_dest();
ciBlock *dest = make_block_at(dest_bci);
break;
}
case Bytecodes::_jsr_w :
{
cur_block->set_control_bci(bci);
ciBlock *ret = make_block_at(s.next_bci());
int dest_bci = s.get_far_dest();
ciBlock *dest = make_block_at(dest_bci);
break;
}
case Bytecodes::_athrow :
cur_block->set_may_throw();
// fall-through
case Bytecodes::_ret :
case Bytecodes::_ireturn :
case Bytecodes::_lreturn :
case Bytecodes::_freturn :
case Bytecodes::_dreturn :
case Bytecodes::_areturn :
case Bytecodes::_return :
cur_block->set_control_bci(bci);
if (s.next_bci() < limit_bci) {
(void) make_block_at(s.next_bci());
}
break;
}
}
// End the last block
cur_block->set_limit_bci(limit_bci);
}
