JDK14/Java14源码在线阅读
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#ifndef SHARE_CI_CITYPEFLOW_HPP
#define SHARE_CI_CITYPEFLOW_HPP
#ifdef COMPILER2
#include "ci/ciEnv.hpp"
#include "ci/ciKlass.hpp"
#include "ci/ciMethodBlocks.hpp"
#endif
class ciTypeFlow : public ResourceObj {
private:
ciEnv* _env;
ciMethod* _method;
ciMethodBlocks* _methodBlocks;
int _osr_bci;
// information cached from the method:
int _max_locals;
int _max_stack;
int _code_size;
bool _has_irreducible_entry;
const char* _failure_reason;
public:
class StateVector;
class Loop;
class Block;
// Build a type flow analyzer
// Do an OSR analysis if osr_bci >= 0.
ciTypeFlow(ciEnv* env, ciMethod* method, int osr_bci = InvocationEntryBci);
// Accessors
ciMethod* method() const { return _method; }
ciEnv* env() { return _env; }
Arena* arena() { return _env->arena(); }
bool is_osr_flow() const{ return _osr_bci != InvocationEntryBci; }
int start_bci() const { return is_osr_flow()? _osr_bci: 0; }
int max_locals() const { return _max_locals; }
int max_stack() const { return _max_stack; }
int max_cells() const { return _max_locals + _max_stack; }
int code_size() const { return _code_size; }
bool has_irreducible_entry() const { return _has_irreducible_entry; }
// Represents information about an "active" jsr call. This
// class represents a call to the routine at some entry address
// with some distinct return address.
class JsrRecord : public ResourceObj {
private:
int _entry_address;
int _return_address;
public:
JsrRecord(int entry_address, int return_address) {
_entry_address = entry_address;
_return_address = return_address;
}
int entry_address() const { return _entry_address; }
int return_address() const { return _return_address; }
void print_on(outputStream* st) const {
#ifndef PRODUCT
st->print("%d->%d", entry_address(), return_address());
#endif
}
};
// A JsrSet represents some set of JsrRecords. This class
// is used to record a set of all jsr routines which we permit
// execution to return (ret) from.
//
// During abstract interpretation, JsrSets are used to determine
// whether two paths which reach a given block are unique, and
// should be cloned apart, or are compatible, and should merge
// together.
//
// Note that different amounts of effort can be expended determining
// if paths are compatible. <DISCUSSION>
class JsrSet : public ResourceObj {
private:
GrowableArray<JsrRecord*>* _set;
JsrRecord* record_at(int i) {
return _set->at(i);
}
// Insert the given JsrRecord into the JsrSet, maintaining the order
// of the set and replacing any element with the same entry address.
void insert_jsr_record(JsrRecord* record);
// Remove the JsrRecord with the given return address from the JsrSet.
void remove_jsr_record(int return_address);
public:
JsrSet(Arena* arena, int default_len = 4);
// Copy this JsrSet.
void copy_into(JsrSet* jsrs);
// Is this JsrSet compatible with some other JsrSet?
bool is_compatible_with(JsrSet* other);
// Apply the effect of a single bytecode to the JsrSet.
void apply_control(ciTypeFlow* analyzer,
ciBytecodeStream* str,
StateVector* state);
// What is the cardinality of this set?
int size() const { return _set->length(); }
void print_on(outputStream* st) const PRODUCT_RETURN;
};
class LocalSet {
private:
enum Constants { max = 63 };
uint64_t _bits;
public:
LocalSet() : _bits(0) {}
void add(uint32_t i) { if (i < (uint32_t)max) _bits |= (1LL << i); }
void add(LocalSet* ls) { _bits |= ls->_bits; }
bool test(uint32_t i) const { return i < (uint32_t)max ? (_bits>>i)&1U : true; }
void clear() { _bits = 0; }
void print_on(outputStream* st, int limit) const PRODUCT_RETURN;
};
// Used as a combined index for locals and temps
enum Cell {
Cell_0, Cell_max = INT_MAX
};
// A StateVector summarizes the type information at some
// point in the program
class StateVector : public ResourceObj {
private:
ciType** _types;
int _stack_size;
int _monitor_count;
ciTypeFlow* _outer;
int _trap_bci;
int _trap_index;
LocalSet _def_locals; // For entire block
static ciType* type_meet_internal(ciType* t1, ciType* t2, ciTypeFlow* analyzer);
public:
// Special elements in our type lattice.
enum {
T_TOP = T_VOID, // why not?
T_BOTTOM = T_CONFLICT,
T_LONG2 = T_SHORT, // 2nd word of T_LONG
T_DOUBLE2 = T_CHAR, // 2nd word of T_DOUBLE
T_NULL = T_BYTE // for now.
};
static ciType* top_type() { return ciType::make((BasicType)T_TOP); }
static ciType* bottom_type() { return ciType::make((BasicType)T_BOTTOM); }
static ciType* long2_type() { return ciType::make((BasicType)T_LONG2); }
static ciType* double2_type(){ return ciType::make((BasicType)T_DOUBLE2); }
static ciType* null_type() { return ciType::make((BasicType)T_NULL); }
static ciType* half_type(ciType* t) {
switch (t->basic_type()) {
case T_LONG: return long2_type();
case T_DOUBLE: return double2_type();
default: ShouldNotReachHere(); return NULL;
}
}
// The meet operation for our type lattice.
ciType* type_meet(ciType* t1, ciType* t2) {
return type_meet_internal(t1, t2, outer());
}
// Accessors
ciTypeFlow* outer() const { return _outer; }
int stack_size() const { return _stack_size; }
void set_stack_size(int ss) { _stack_size = ss; }
int monitor_count() const { return _monitor_count; }
void set_monitor_count(int mc) { _monitor_count = mc; }
LocalSet* def_locals() { return &_def_locals; }
const LocalSet* def_locals() const { return &_def_locals; }
static Cell start_cell() { return (Cell)0; }
static Cell next_cell(Cell c) { return (Cell)(((int)c) + 1); }
Cell limit_cell() const {
return (Cell)(outer()->max_locals() + stack_size());
}
// Cell creation
Cell local(int lnum) const {
assert(lnum < outer()->max_locals(), "index check");
return (Cell)(lnum);
}
Cell stack(int snum) const {
assert(snum < stack_size(), "index check");
return (Cell)(outer()->max_locals() + snum);
}
Cell tos() const { return stack(stack_size()-1); }
// For external use only:
ciType* local_type_at(int i) const { return type_at(local(i)); }
ciType* stack_type_at(int i) const { return type_at(stack(i)); }
// Accessors for the type of some Cell c
ciType* type_at(Cell c) const {
assert(start_cell() <= c && c < limit_cell(), "out of bounds");
return _types[c];
}
void set_type_at(Cell c, ciType* type) {
assert(start_cell() <= c && c < limit_cell(), "out of bounds");
_types[c] = type;
}
// Top-of-stack operations.
void set_type_at_tos(ciType* type) { set_type_at(tos(), type); }
ciType* type_at_tos() const { return type_at(tos()); }
void push(ciType* type) {
_stack_size++;
set_type_at_tos(type);
}
void pop() {
debug_only(set_type_at_tos(bottom_type()));
_stack_size--;
}
ciType* pop_value() {
ciType* t = type_at_tos();
pop();
return t;
}
// Convenience operations.
bool is_reference(ciType* type) const {
return type == null_type() || !type->is_primitive_type();
}
bool is_int(ciType* type) const {
return type->basic_type() == T_INT;
}
bool is_long(ciType* type) const {
return type->basic_type() == T_LONG;
}
bool is_float(ciType* type) const {
return type->basic_type() == T_FLOAT;
}
bool is_double(ciType* type) const {
return type->basic_type() == T_DOUBLE;
}
void store_to_local(int lnum) {
_def_locals.add((uint) lnum);
}
void push_translate(ciType* type);
void push_int() {
push(ciType::make(T_INT));
}
void pop_int() {
assert(is_int(type_at_tos()), "must be integer");
pop();
}
void check_int(Cell c) {
assert(is_int(type_at(c)), "must be integer");
}
void push_double() {
push(ciType::make(T_DOUBLE));
push(double2_type());
}
void pop_double() {
assert(type_at_tos() == double2_type(), "must be 2nd half");
pop();
assert(is_double(type_at_tos()), "must be double");
pop();
}
void push_float() {
push(ciType::make(T_FLOAT));
}
void pop_float() {
assert(is_float(type_at_tos()), "must be float");
pop();
}
void push_long() {
push(ciType::make(T_LONG));
push(long2_type());
}
void pop_long() {
assert(type_at_tos() == long2_type(), "must be 2nd half");
pop();
assert(is_long(type_at_tos()), "must be long");
pop();
}
void push_object(ciKlass* klass) {
push(klass);
}
void pop_object() {
assert(is_reference(type_at_tos()), "must be reference type");
pop();
}
void pop_array() {
assert(type_at_tos() == null_type() ||
type_at_tos()->is_array_klass(), "must be array type");
pop();
}
// pop_objArray and pop_typeArray narrow the tos to ciObjArrayKlass
// or ciTypeArrayKlass (resp.). In the rare case that an explicit
// null is popped from the stack, we return NULL. Caller beware.
ciObjArrayKlass* pop_objArray() {
ciType* array = pop_value();
if (array == null_type()) return NULL;
assert(array->is_obj_array_klass(), "must be object array type");
return array->as_obj_array_klass();
}
ciTypeArrayKlass* pop_typeArray() {
ciType* array = pop_value();
if (array == null_type()) return NULL;
assert(array->is_type_array_klass(), "must be prim array type");
return array->as_type_array_klass();
}
void push_null() {
push(null_type());
}
void do_null_assert(ciKlass* unloaded_klass);
// Helper convenience routines.
void do_aaload(ciBytecodeStream* str);
void do_checkcast(ciBytecodeStream* str);
void do_getfield(ciBytecodeStream* str);
void do_getstatic(ciBytecodeStream* str);
void do_invoke(ciBytecodeStream* str, bool has_receiver);
void do_jsr(ciBytecodeStream* str);
void do_ldc(ciBytecodeStream* str);
void do_multianewarray(ciBytecodeStream* str);
void do_new(ciBytecodeStream* str);
void do_newarray(ciBytecodeStream* str);
void do_putfield(ciBytecodeStream* str);
void do_putstatic(ciBytecodeStream* str);
void do_ret(ciBytecodeStream* str);
void overwrite_local_double_long(int index) {
// Invalidate the previous local if it contains first half of
// a double or long value since it's seconf half is being overwritten.
int prev_index = index - 1;
if (prev_index >= 0 &&
(is_double(type_at(local(prev_index))) ||
is_long(type_at(local(prev_index))))) {
set_type_at(local(prev_index), bottom_type());
}
}
void load_local_object(int index) {
ciType* type = type_at(local(index));
assert(is_reference(type), "must be reference type");
push(type);
}
void store_local_object(int index) {
ciType* type = pop_value();
assert(is_reference(type) || type->is_return_address(),
"must be reference type or return address");
overwrite_local_double_long(index);
set_type_at(local(index), type);
store_to_local(index);
}
void load_local_double(int index) {
ciType* type = type_at(local(index));
ciType* type2 = type_at(local(index+1));
assert(is_double(type), "must be double type");
assert(type2 == double2_type(), "must be 2nd half");
push(type);
push(double2_type());
}
void store_local_double(int index) {
ciType* type2 = pop_value();
ciType* type = pop_value();
assert(is_double(type), "must be double");
assert(type2 == double2_type(), "must be 2nd half");
overwrite_local_double_long(index);
set_type_at(local(index), type);
set_type_at(local(index+1), type2);
store_to_local(index);
store_to_local(index+1);
}
void load_local_float(int index) {
ciType* type = type_at(local(index));
assert(is_float(type), "must be float type");
push(type);
}
void store_local_float(int index) {
ciType* type = pop_value();
assert(is_float(type), "must be float type");
overwrite_local_double_long(index);
set_type_at(local(index), type);
store_to_local(index);
}
void load_local_int(int index) {
ciType* type = type_at(local(index));
assert(is_int(type), "must be int type");
push(type);
}
void store_local_int(int index) {
ciType* type = pop_value();
assert(is_int(type), "must be int type");
overwrite_local_double_long(index);
set_type_at(local(index), type);
store_to_local(index);
}
void load_local_long(int index) {
ciType* type = type_at(local(index));
ciType* type2 = type_at(local(index+1));
assert(is_long(type), "must be long type");
assert(type2 == long2_type(), "must be 2nd half");
push(type);
push(long2_type());
}
void store_local_long(int index) {
ciType* type2 = pop_value();
ciType* type = pop_value();
assert(is_long(type), "must be long");
assert(type2 == long2_type(), "must be 2nd half");
overwrite_local_double_long(index);
set_type_at(local(index), type);
set_type_at(local(index+1), type2);
store_to_local(index);
store_to_local(index+1);
}
// Stop interpretation of this path with a trap.
void trap(ciBytecodeStream* str, ciKlass* klass, int index);
public:
StateVector(ciTypeFlow* outer);
// Copy our value into some other StateVector
void copy_into(StateVector* copy) const;
// Meets this StateVector with another, destructively modifying this
// one. Returns true if any modification takes place.
bool meet(const StateVector* incoming);
// Ditto, except that the incoming state is coming from an exception.
bool meet_exception(ciInstanceKlass* exc, const StateVector* incoming);
// Apply the effect of one bytecode to this StateVector
bool apply_one_bytecode(ciBytecodeStream* stream);
// What is the bci of the trap?
int trap_bci() { return _trap_bci; }
// What is the index associated with the trap?
int trap_index() { return _trap_index; }
void print_cell_on(outputStream* st, Cell c) const PRODUCT_RETURN;
void print_on(outputStream* st) const PRODUCT_RETURN;
};
// Parameter for "find_block" calls:
// Describes the difference between a public and backedge copy.
enum CreateOption {
create_public_copy,
create_backedge_copy,
no_create
};
// Successor iterator
class SuccIter : public StackObj {
private:
Block* _pred;
int _index;
Block* _succ;
public:
SuccIter() : _pred(NULL), _index(-1), _succ(NULL) {}
SuccIter(Block* pred) : _pred(pred), _index(-1), _succ(NULL) { next(); }
int index() { return _index; }
Block* pred() { return _pred; } // Return predecessor
bool done() { return _index < 0; } // Finished?
Block* succ() { return _succ; } // Return current successor
void next(); // Advance
void set_succ(Block* succ); // Update current successor
bool is_normal_ctrl() { return index() < _pred->successors()->length(); }
};
// A basic block
class Block : public ResourceObj {
private:
ciBlock* _ciblock;
GrowableArray<Block*>* _exceptions;
GrowableArray<ciInstanceKlass*>* _exc_klasses;
GrowableArray<Block*>* _successors;
GrowableArray<Block*>* _predecessors;
StateVector* _state;
JsrSet* _jsrs;
int _trap_bci;
int _trap_index;
// pre_order, assigned at first visit. Used as block ID and "visited" tag
int _pre_order;
// A post-order, used to compute the reverse post order (RPO) provided to the client
int _post_order; // used to compute rpo
// Has this block been cloned for a loop backedge?
bool _backedge_copy;
// This block is entry to irreducible loop.
bool _irreducible_entry;
// This block has monitor entry point.
bool _has_monitorenter;
// A pointer used for our internal work list
bool _on_work_list; // on the work list
Block* _next;
Block* _rpo_next; // Reverse post order list
// Loop info
Loop* _loop; // nearest loop
ciBlock* ciblock() const { return _ciblock; }
StateVector* state() const { return _state; }
// Compute the exceptional successors and types for this Block.
void compute_exceptions();
public:
// constructors
Block(ciTypeFlow* outer, ciBlock* ciblk, JsrSet* jsrs);
void set_trap(int trap_bci, int trap_index) {
_trap_bci = trap_bci;
_trap_index = trap_index;
assert(has_trap(), "");
}
bool has_trap() const { return _trap_bci != -1; }
int trap_bci() const { assert(has_trap(), ""); return _trap_bci; }
int trap_index() const { assert(has_trap(), ""); return _trap_index; }
// accessors
ciTypeFlow* outer() const { return state()->outer(); }
int start() const { return _ciblock->start_bci(); }
int limit() const { return _ciblock->limit_bci(); }
int control() const { return _ciblock->control_bci(); }
JsrSet* jsrs() const { return _jsrs; }
bool is_backedge_copy() const { return _backedge_copy; }
void set_backedge_copy(bool z);
int backedge_copy_count() const { return outer()->backedge_copy_count(ciblock()->index(), _jsrs); }
// access to entry state
int stack_size() const { return _state->stack_size(); }
int monitor_count() const { return _state->monitor_count(); }
ciType* local_type_at(int i) const { return _state->local_type_at(i); }
ciType* stack_type_at(int i) const { return _state->stack_type_at(i); }
// Data flow on locals
bool is_invariant_local(uint v) const {
assert(is_loop_head(), "only loop heads");
// Find outermost loop with same loop head
Loop* lp = loop();
while (lp->parent() != NULL) {
if (lp->parent()->head() != lp->head()) break;
lp = lp->parent();
}
return !lp->def_locals()->test(v);
}
LocalSet* def_locals() { return _state->def_locals(); }
const LocalSet* def_locals() const { return _state->def_locals(); }
// Get the successors for this Block.
GrowableArray<Block*>* successors(ciBytecodeStream* str,
StateVector* state,
JsrSet* jsrs);
GrowableArray<Block*>* successors() {
assert(_successors != NULL, "must be filled in");
return _successors;
}
// Predecessors of this block (including exception edges)
GrowableArray<Block*>* predecessors() {
assert(_predecessors != NULL, "must be filled in");
return _predecessors;
}
// Get the exceptional successors for this Block.
GrowableArray<Block*>* exceptions() {
if (_exceptions == NULL) {
compute_exceptions();
}
return _exceptions;
}
// Get the exception klasses corresponding to the
// exceptional successors for this Block.
GrowableArray<ciInstanceKlass*>* exc_klasses() {
if (_exc_klasses == NULL) {
compute_exceptions();
}
return _exc_klasses;
}
// Is this Block compatible with a given JsrSet?
bool is_compatible_with(JsrSet* other) {
return _jsrs->is_compatible_with(other);
}
// Copy the value of our state vector into another.
void copy_state_into(StateVector* copy) const {
_state->copy_into(copy);
}
// Copy the value of our JsrSet into another
void copy_jsrs_into(JsrSet* copy) const {
_jsrs->copy_into(copy);
}
// Meets the start state of this block with another state, destructively
// modifying this one. Returns true if any modification takes place.
bool meet(const StateVector* incoming) {
return state()->meet(incoming);
}
// Ditto, except that the incoming state is coming from an
// exception path. This means the stack is replaced by the
// appropriate exception type.
bool meet_exception(ciInstanceKlass* exc, const StateVector* incoming) {
return state()->meet_exception(exc, incoming);
}
// Work list manipulation
void set_next(Block* block) { _next = block; }
Block* next() const { return _next; }
void set_on_work_list(bool c) { _on_work_list = c; }
bool is_on_work_list() const { return _on_work_list; }
bool has_pre_order() const { return _pre_order >= 0; }
void set_pre_order(int po) { assert(!has_pre_order(), ""); _pre_order = po; }
int pre_order() const { assert(has_pre_order(), ""); return _pre_order; }
void set_next_pre_order() { set_pre_order(outer()->inc_next_pre_order()); }
bool is_start() const { return _pre_order == outer()->start_block_num(); }
// Reverse post order
void df_init();
bool has_post_order() const { return _post_order >= 0; }
void set_post_order(int po) { assert(!has_post_order() && po >= 0, ""); _post_order = po; }
void reset_post_order(int o){ _post_order = o; }
int post_order() const { assert(has_post_order(), ""); return _post_order; }
bool has_rpo() const { return has_post_order() && outer()->have_block_count(); }
int rpo() const { assert(has_rpo(), ""); return outer()->block_count() - post_order() - 1; }
void set_rpo_next(Block* b) { _rpo_next = b; }
Block* rpo_next() { return _rpo_next; }
// Loops
Loop* loop() const { return _loop; }
void set_loop(Loop* lp) { _loop = lp; }
bool is_loop_head() const { return _loop && _loop->head() == this; }
void set_irreducible_entry(bool c) { _irreducible_entry = c; }
bool is_irreducible_entry() const { return _irreducible_entry; }
void set_has_monitorenter() { _has_monitorenter = true; }
bool has_monitorenter() const { return _has_monitorenter; }
bool is_visited() const { return has_pre_order(); }
bool is_post_visited() const { return has_post_order(); }
bool is_clonable_exit(Loop* lp);
Block* looping_succ(Loop* lp); // Successor inside of loop
bool is_single_entry_loop_head() const {
if (!is_loop_head()) return false;
for (Loop* lp = loop(); lp != NULL && lp->head() == this; lp = lp->parent())
if (lp->is_irreducible()) return false;
return true;
}
void print_value_on(outputStream* st) const PRODUCT_RETURN;
void print_on(outputStream* st) const PRODUCT_RETURN;
};
// Loop
class Loop : public ResourceObj {
private:
Loop* _parent;
Loop* _sibling; // List of siblings, null terminated
Loop* _child; // Head of child list threaded thru sibling pointer
Block* _head; // Head of loop
Block* _tail; // Tail of loop
bool _irreducible;
LocalSet _def_locals;
public:
Loop(Block* head, Block* tail) :
_parent(NULL), _sibling(NULL), _child(NULL),
_head(head), _tail(tail),
_irreducible(false), _def_locals() {}
Loop* parent() const { return _parent; }
Loop* sibling() const { return _sibling; }
Loop* child() const { return _child; }
Block* head() const { return _head; }
Block* tail() const { return _tail; }
void set_parent(Loop* p) { _parent = p; }
void set_sibling(Loop* s) { _sibling = s; }
void set_child(Loop* c) { _child = c; }
void set_head(Block* hd) { _head = hd; }
void set_tail(Block* tl) { _tail = tl; }
int depth() const; // nesting depth
// Returns true if lp is a nested loop or us.
bool contains(Loop* lp) const;
bool contains(Block* blk) const { return contains(blk->loop()); }
// Data flow on locals
LocalSet* def_locals() { return &_def_locals; }
const LocalSet* def_locals() const { return &_def_locals; }
// Merge the branch lp into this branch, sorting on the loop head
// pre_orders. Returns the new branch.
Loop* sorted_merge(Loop* lp);
// Mark non-single entry to loop
void set_irreducible(Block* entry) {
_irreducible = true;
entry->set_irreducible_entry(true);
}
bool is_irreducible() const { return _irreducible; }
bool is_root() const { return _tail->pre_order() == max_jint; }
void print(outputStream* st = tty, int indent = 0) const PRODUCT_RETURN;
};
// Preorder iteration over the loop tree.
class PreorderLoops : public StackObj {
private:
Loop* _root;
Loop* _current;
public:
PreorderLoops(Loop* root) : _root(root), _current(root) {}
bool done() { return _current == NULL; } // Finished iterating?
void next(); // Advance to next loop
Loop* current() { return _current; } // Return current loop.
};
// Standard indexes of successors, for various bytecodes.
enum {
FALL_THROUGH = 0, // normal control
IF_NOT_TAKEN = 0, // the not-taken branch of an if (i.e., fall-through)
IF_TAKEN = 1, // the taken branch of an if
GOTO_TARGET = 0, // unique successor for goto, jsr, or ret
SWITCH_DEFAULT = 0, // default branch of a switch
SWITCH_CASES = 1 // first index for any non-default switch branches
// Unlike in other blocks, the successors of a switch are listed uniquely.
};
private:
// A mapping from pre_order to Blocks. This array is created
// only at the end of the flow.
Block** _block_map;
// For each ciBlock index, a list of Blocks which share this ciBlock.
GrowableArray<Block*>** _idx_to_blocklist;
// count of ciBlocks
int _ciblock_count;
// Tells if a given instruction is able to generate an exception edge.
bool can_trap(ciBytecodeStream& str);
// Clone the loop heads. Returns true if any cloning occurred.
bool clone_loop_heads(Loop* lp, StateVector* temp_vector, JsrSet* temp_set);
// Clone lp's head and replace tail's successors with clone.
Block* clone_loop_head(Loop* lp, StateVector* temp_vector, JsrSet* temp_set);
public:
// Return the block beginning at bci which has a JsrSet compatible
// with jsrs.
Block* block_at(int bci, JsrSet* set, CreateOption option = create_public_copy);
// block factory
Block* get_block_for(int ciBlockIndex, JsrSet* jsrs, CreateOption option = create_public_copy);
// How many of the blocks have the backedge_copy bit set?
int backedge_copy_count(int ciBlockIndex, JsrSet* jsrs) const;
// Return an existing block containing bci which has a JsrSet compatible
// with jsrs, or NULL if there is none.
Block* existing_block_at(int bci, JsrSet* set) { return block_at(bci, set, no_create); }
// Tell whether the flow analysis has encountered an error of some sort.
bool failing() { return env()->failing() || _failure_reason != NULL; }
// Reason this compilation is failing, such as "too many basic blocks".
const char* failure_reason() { return _failure_reason; }
// Note a failure.
void record_failure(const char* reason);
// Return the block of a given pre-order number.
int have_block_count() const { return _block_map != NULL; }
int block_count() const { assert(have_block_count(), "");
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