1N/A

1N/A

1N/Aclass ciEnv;

1N/Aclass nmethod;

1N/Aclass OopRecorder;

1N/Aclass xmlStream;

1N/Aclass CompileLog;

1N/Aclass DepChange;

1N/Aclass No_Safepoint_Verifier;

1N/A

1N/Aclass Dependencies: public ResourceObj {

1N/A public:

1N/A // Note: In the comments on dependency types, most uses of the terms

1N/A // subtype and supertype are used in a "non-strict" or "inclusive"

1N/A // sense, and are starred to remind the reader of this fact.

1N/A // Strict uses of the terms use the word "proper".

1N/A //

1N/A // Specifically, every class is its own subtype* and supertype*.

1N/A // (This trick is easier than continually saying things like "Y is a

1N/A // subtype of X or X itself".)

1N/A //

1N/A // Sometimes we write X > Y to mean X is a proper supertype of Y.

1N/A // The notation X > {Y, Z} means X has proper subtypes Y, Z.

1N/A // The notation X.m > Y means that Y inherits m from X, while

1N/A // X.m > Y.m means Y overrides X.m. A star denotes abstractness,

1N/A // as *I > A, meaning (abstract) interface I is a super type of A,

1N/A // or A.*m > B.m, meaning B.m implements abstract method A.m.

1N/A //

1N/A // In this module, the terms "subtype" and "supertype" refer to

1N/A // Java-level reference type conversions, as detected by

1N/A // "instanceof" and performed by "checkcast" operations. The method

1N/A // Klass::is_subtype_of tests these relations. Note that "subtype"

1N/A // is richer than "subclass" (as tested by Klass::is_subclass_of),

1N/A // since it takes account of relations involving interface and array

1N/A // types.

1N/A //

1N/A // To avoid needless complexity, dependencies involving array types

1N/A // are not accepted. If you need to make an assertion about an

1N/A // array type, make the assertion about its corresponding element

1N/A // types. Any assertion that might change about an array type can

1N/A // be converted to an assertion about its element type.

1N/A //

1N/A // Most dependencies are evaluated over a "context type" CX, which

1N/A // stands for the set Subtypes(CX) of every Java type that is a subtype*

1N/A // of CX. When the system loads a new class or interface N, it is

1N/A // responsible for re-evaluating changed dependencies whose context

1N/A // type now includes N, that is, all super types of N.

1N/A //

1N/A enum DepType {

1N/A end_marker = 0,

1N/A

1N/A // An 'evol' dependency simply notes that the contents of the

1N/A // method were used. If it evolves (is replaced), the nmethod

1N/A // must be recompiled. No other dependencies are implied.

1N/A evol_method,

1N/A FIRST_TYPE = evol_method,

1N/A

1N/A // A context type CX is a leaf it if has no proper subtype.

1N/A leaf_type,

1N/A

1N/A // An abstract class CX has exactly one concrete subtype CC.

1N/A abstract_with_unique_concrete_subtype,

1N/A

1N/A // The type CX is purely abstract, with no concrete subtype* at all.

1N/A abstract_with_no_concrete_subtype,

1N/A

1N/A // The concrete CX is free of concrete proper subtypes.

1N/A concrete_with_no_concrete_subtype,

1N/A

1N/A // Given a method M1 and a context class CX, the set MM(CX, M1) of

1N/A // "concrete matching methods" in CX of M1 is the set of every

1N/A // concrete M2 for which it is possible to create an invokevirtual

1N/A // or invokeinterface call site that can reach either M1 or M2.

1N/A // That is, M1 and M2 share a name, signature, and vtable index.

1N/A // We wish to notice when the set MM(CX, M1) is just {M1}, or

1N/A // perhaps a set of two {M1,M2}, and issue dependencies on this.

1N/A

1N/A // The set MM(CX, M1) can be computed by starting with any matching

1N/A // concrete M2 that is inherited into CX, and then walking the

1N/A // subtypes* of CX looking for concrete definitions.

1N/A

// The parameters to this dependency are the method M1 and the

// context class CX. M1 must be either inherited in CX or defined

// in a subtype* of CX. It asserts that MM(CX, M1) is no greater

// than {M1}.

unique_concrete_method, // one unique concrete method under CX

// An "exclusive" assertion concerns two methods or subtypes, and

// declares that there are at most two (or perhaps later N>2)

// specific items that jointly satisfy the restriction.

// We list all items explicitly rather than just giving their

// count, for robustness in the face of complex schema changes.

// A context class CX (which may be either abstract or concrete)

// has two exclusive concrete subtypes* C1, C2 if every concrete

// subtype* of CX is either C1 or C2. Note that if neither C1 or C2

// are equal to CX, then CX itself must be abstract. But it is

// also possible (for example) that C1 is CX (a concrete class)

// and C2 is a proper subtype of C1.

abstract_with_exclusive_concrete_subtypes_2,

// This dependency asserts that MM(CX, M1) is no greater than {M1,M2}.

exclusive_concrete_methods_2,

// This dependency asserts that no instances of class or it's

// subclasses require finalization registration.

no_finalizable_subclasses,

TYPE_LIMIT

};

enum {

LG2_TYPE_LIMIT = 4, // assert(TYPE_LIMIT <= (1<<LG2_TYPE_LIMIT))

// handy categorizations of dependency types:

all_types = ((1<<TYPE_LIMIT)-1) & ((-1)<<FIRST_TYPE),

non_ctxk_types = (1<<evol_method),

ctxk_types = all_types & ~non_ctxk_types,

max_arg_count = 3, // current maximum number of arguments (incl. ctxk)

// A "context type" is a class or interface that

// provides context for evaluating a dependency.

// When present, it is one of the arguments (dep_context_arg).

//

// If a dependency does not have a context type, there is a

// default context, depending on the type of the dependency.

// This bit signals that a default context has been compressed away.

default_context_type_bit = (1<<LG2_TYPE_LIMIT)

};

static const char* dep_name(DepType dept);

static int dep_args(DepType dept);

static int dep_context_arg(DepType dept) {

return dept_in_mask(dept, ctxk_types)? 0: -1;

}

private:

// State for writing a new set of dependencies:

GrowableArray<int>* _dep_seen; // (seen[h->ident] & (1<<dept))

GrowableArray<ciObject*>* _deps[TYPE_LIMIT];

static const char* _dep_name[TYPE_LIMIT];

static int _dep_args[TYPE_LIMIT];

static bool dept_in_mask(DepType dept, int mask) {

return (int)dept >= 0 && dept < TYPE_LIMIT && ((1<<dept) & mask) != 0;

}

bool note_dep_seen(int dept, ciObject* x) {

assert(dept < BitsPerInt, "oob");

int x_id = x->ident();

assert(_dep_seen != NULL, "deps must be writable");

int seen = _dep_seen->at_grow(x_id, 0);

_dep_seen->at_put(x_id, seen | (1<<dept));

// return true if we've already seen dept/x

return (seen & (1<<dept)) != 0;

}

bool maybe_merge_ctxk(GrowableArray<ciObject*>* deps,

int ctxk_i, ciKlass* ctxk);

void sort_all_deps();

size_t estimate_size_in_bytes();

// Initialize _deps, etc.

void initialize(ciEnv* env);

// State for making a new set of dependencies:

OopRecorder* _oop_recorder;

// Logging support

CompileLog* _log;

address _content_bytes; // everything but the oop references, encoded

size_t _size_in_bytes;

public:

// Make a new empty dependencies set.

Dependencies(ciEnv* env) {

initialize(env);

}

private:

// Check for a valid context type.

// Enforce the restriction against array types.

static void check_ctxk(ciKlass* ctxk) {

assert(ctxk->is_instance_klass(), "java types only");

}

static void check_ctxk_concrete(ciKlass* ctxk) {

assert(is_concrete_klass(ctxk->as_instance_klass()), "must be concrete");

}

static void check_ctxk_abstract(ciKlass* ctxk) {

check_ctxk(ctxk);

assert(!is_concrete_klass(ctxk->as_instance_klass()), "must be abstract");

}

void assert_common_1(DepType dept, ciObject* x);

void assert_common_2(DepType dept, ciKlass* ctxk, ciObject* x);

void assert_common_3(DepType dept, ciKlass* ctxk, ciObject* x, ciObject* x2);

public:

// Adding assertions to a new dependency set at compile time:

void assert_evol_method(ciMethod* m);

void assert_leaf_type(ciKlass* ctxk);

void assert_abstract_with_unique_concrete_subtype(ciKlass* ctxk, ciKlass* conck);

void assert_abstract_with_no_concrete_subtype(ciKlass* ctxk);

void assert_concrete_with_no_concrete_subtype(ciKlass* ctxk);

void assert_unique_concrete_method(ciKlass* ctxk, ciMethod* uniqm);

void assert_abstract_with_exclusive_concrete_subtypes(ciKlass* ctxk, ciKlass* k1, ciKlass* k2);

void assert_exclusive_concrete_methods(ciKlass* ctxk, ciMethod* m1, ciMethod* m2);

void assert_has_no_finalizable_subclasses(ciKlass* ctxk);

// Define whether a given method or type is concrete.

// These methods define the term "concrete" as used in this module.

// For this module, an "abstract" class is one which is non-concrete.

//

// Future optimizations may allow some classes to remain

// non-concrete until their first instantiation, and allow some

// methods to remain non-concrete until their first invocation.

// In that case, there would be a middle ground between concrete

// and abstract (as defined by the Java language and VM).

static bool is_concrete_klass(klassOop k); // k is instantiable

static bool is_concrete_method(methodOop m); // m is invocable

static Klass* find_finalizable_subclass(Klass* k);

// These versions of the concreteness queries work through the CI.

// The CI versions are allowed to skew sometimes from the VM

// (oop-based) versions. The cost of such a difference is a

// (safely) aborted compilation, or a deoptimization, or a missed

// optimization opportunity.

//

// In order to prevent spurious assertions, query results must

// remain stable within any single ciEnv instance. (I.e., they must

// not go back into the VM to get their value; they must cache the

// bit in the CI, either eagerly or lazily.)

static bool is_concrete_klass(ciInstanceKlass* k); // k appears instantiable

static bool is_concrete_method(ciMethod* m); // m appears invocable

static bool has_finalizable_subclass(ciInstanceKlass* k);

// As a general rule, it is OK to compile under the assumption that

// a given type or method is concrete, even if it at some future

// point becomes abstract. So dependency checking is one-sided, in

// that it permits supposedly concrete classes or methods to turn up

// as really abstract. (This shouldn't happen, except during class

// evolution, but that's the logic of the checking.) However, if a

// supposedly abstract class or method suddenly becomes concrete, a

// dependency on it must fail.

// Checking old assertions at run-time (in the VM only):

static klassOop check_evol_method(methodOop m);

static klassOop check_leaf_type(klassOop ctxk);

static klassOop check_abstract_with_unique_concrete_subtype(klassOop ctxk, klassOop conck,

DepChange* changes = NULL);

static klassOop check_abstract_with_no_concrete_subtype(klassOop ctxk,

DepChange* changes = NULL);

static klassOop check_concrete_with_no_concrete_subtype(klassOop ctxk,

DepChange* changes = NULL);

static klassOop check_unique_concrete_method(klassOop ctxk, methodOop uniqm,

DepChange* changes = NULL);

static klassOop check_abstract_with_exclusive_concrete_subtypes(klassOop ctxk, klassOop k1, klassOop k2,

DepChange* changes = NULL);

static klassOop check_exclusive_concrete_methods(klassOop ctxk, methodOop m1, methodOop m2,

DepChange* changes = NULL);

static klassOop check_has_no_finalizable_subclasses(klassOop ctxk,

DepChange* changes = NULL);

// A returned klassOop is NULL if the dependency assertion is still

// valid. A non-NULL klassOop is a 'witness' to the assertion

// failure, a point in the class hierarchy where the assertion has

// been proven false. For example, if check_leaf_type returns

// non-NULL, the value is a subtype of the supposed leaf type. This

// witness value may be useful for logging the dependency failure.

// Note that, when a dependency fails, there may be several possible

// witnesses to the failure. The value returned from the check_foo

// method is chosen arbitrarily.

// The 'changes' value, if non-null, requests a limited spot-check

// near the indicated recent changes in the class hierarchy.

// It is used by DepStream::spot_check_dependency_at.

// Detecting possible new assertions:

static klassOop find_unique_concrete_subtype(klassOop ctxk);

static methodOop find_unique_concrete_method(klassOop ctxk, methodOop m);

static int find_exclusive_concrete_subtypes(klassOop ctxk, int klen, klassOop k[]);

static int find_exclusive_concrete_methods(klassOop ctxk, int mlen, methodOop m[]);

// Create the encoding which will be stored in an nmethod.

void encode_content_bytes();

address content_bytes() {

assert(_content_bytes != NULL, "encode it first");

return _content_bytes;

}

size_t size_in_bytes() {

assert(_content_bytes != NULL, "encode it first");

return _size_in_bytes;

}

OopRecorder* oop_recorder() { return _oop_recorder; }

CompileLog* log() { return _log; }

void copy_to(nmethod* nm);

void log_all_dependencies();

void log_dependency(DepType dept, int nargs, ciObject* args[]) {

write_dependency_to(log(), dept, nargs, args);

}

void log_dependency(DepType dept,

ciObject* x0,

ciObject* x1 = NULL,

ciObject* x2 = NULL) {

if (log() == NULL) return;

ciObject* args[max_arg_count];

args[0] = x0;

args[1] = x1;

args[2] = x2;

assert(2 < max_arg_count, "");

log_dependency(dept, dep_args(dept), args);

}

static void write_dependency_to(CompileLog* log,

DepType dept,

int nargs, ciObject* args[],

klassOop witness = NULL);

static void write_dependency_to(CompileLog* log,

DepType dept,

int nargs, oop args[],

klassOop witness = NULL);

static void write_dependency_to(xmlStream* xtty,

DepType dept,

int nargs, oop args[],

klassOop witness = NULL);

static void print_dependency(DepType dept,

int nargs, oop args[],

klassOop witness = NULL);

private:

// helper for encoding common context types as zero:

static ciKlass* ctxk_encoded_as_null(DepType dept, ciObject* x);

static klassOop ctxk_encoded_as_null(DepType dept, oop x);

public:

// Use this to iterate over an nmethod's dependency set.

// Works on new and old dependency sets.

// Usage:

//

// ;

// Dependencies::DepType dept;

// for (Dependencies::DepStream deps(nm); deps.next(); ) {

// ...

// }

//

// The caller must be in the VM, since oops are not wrapped in handles.

class DepStream {

private:

nmethod* _code; // null if in a compiler thread

Dependencies* _deps; // null if not in a compiler thread

CompressedReadStream _bytes;

#ifdef ASSERT

size_t _byte_limit;

#endif

// iteration variables:

DepType _type;

int _xi[max_arg_count+1];

void initial_asserts(size_t byte_limit) NOT_DEBUG({});

inline oop recorded_oop_at(int i);

// => _code? _code->oop_at(i): *_deps->_oop_recorder->handle_at(i)

klassOop check_dependency_impl(DepChange* changes);

public:

DepStream(Dependencies* deps)

: _deps(deps),

_code(NULL),

_bytes(deps->content_bytes())

{

initial_asserts(deps->size_in_bytes());

}

DepStream(nmethod* code)

: _deps(NULL),

_code(code),

_bytes(code->dependencies_begin())

{

initial_asserts(code->dependencies_size());

}

bool next();

DepType type() { return _type; }

int argument_count() { return dep_args(type()); }

int argument_index(int i) { assert(0 <= i && i < argument_count(), "oob");

return _xi[i]; }

oop argument(int i); // => recorded_oop_at(argument_index(i))

klassOop context_type();

methodOop method_argument(int i) {

oop x = argument(i);

assert(x->is_method(), "type");

return (methodOop) x;

}

klassOop type_argument(int i) {

oop x = argument(i);

assert(x->is_klass(), "type");

return (klassOop) x;

}

// The point of the whole exercise: Is this dep is still OK?

klassOop check_dependency() {

return check_dependency_impl(NULL);

}

// A lighter version: Checks only around recent changes in a class

// hierarchy. (See Universe::flush_dependents_on.)

klassOop spot_check_dependency_at(DepChange& changes);

// Log the current dependency to xtty or compilation log.

void log_dependency(klassOop witness = NULL);

// Print the current dependency to tty.

void print_dependency(klassOop witness = NULL, bool verbose = false);

};

friend class Dependencies::DepStream;

static void print_statistics() PRODUCT_RETURN;

};

class DepChange : public StackObj {

public:

enum ChangeType {

NO_CHANGE = 0, // an uninvolved klass

Change_new_type, // a newly loaded type

Change_new_sub, // a super with a new subtype

Change_new_impl, // an interface with a new implementation

CHANGE_LIMIT,

Start_Klass = CHANGE_LIMIT // internal indicator for ContextStream

};

private:

// each change set is rooted in exactly one new type (at present):

KlassHandle _new_type;

void initialize();

public:

// notes the new type, marks it and all its super-types

DepChange(KlassHandle new_type)

: _new_type(new_type)

{

initialize();

}

// cleans up the marks

~DepChange();

klassOop new_type() { return _new_type(); }

// involves_context(k) is true if k is new_type or any of the super types

bool involves_context(klassOop k);

// Usage:

// for (DepChange::ContextStream str(changes); str.next(); ) {

// klassOop k = str.klass();

// switch (str.change_type()) {

// ...

// }

// }

class ContextStream : public StackObj {

private:

DepChange& _changes;

friend class DepChange;

// iteration variables:

ChangeType _change_type;

klassOop _klass;

objArrayOop _ti_base; // i.e., transitive_interfaces

int _ti_index;

int _ti_limit;

// start at the beginning:

void start() {

klassOop new_type = _changes.new_type();

_change_type = (new_type == NULL ? NO_CHANGE: Start_Klass);

_klass = new_type;

_ti_base = NULL;

_ti_index = 0;

_ti_limit = 0;

}

public:

ContextStream(DepChange& changes)

: _changes(changes)

{ start(); }

ContextStream(DepChange& changes, No_Safepoint_Verifier& nsv)

: _changes(changes)

// the nsv argument makes it safe to hold oops like _klass

{ start(); }

bool next();

ChangeType change_type() { return _change_type; }

klassOop klass() { return _klass; }

};

friend class DepChange::ContextStream;

void print();

};