/*
* Copyright (c) 2005, 2019, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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*/
#ifndef SHARE_CODE_DEPENDENCIES_HPP
#define SHARE_CODE_DEPENDENCIES_HPP
#include "ci/ciCallSite.hpp"
#include "ci/ciKlass.hpp"
#include "ci/ciMethod.hpp"
#include "ci/ciMethodHandle.hpp"
#include "classfile/systemDictionary.hpp"
#include "code/compressedStream.hpp"
#include "code/nmethod.hpp"
#include "memory/resourceArea.hpp"
#include "runtime/safepointVerifiers.hpp"
#include "utilities/growableArray.hpp"
#include "utilities/hashtable.hpp"
//** Dependencies represent assertions (approximate invariants) within
// the runtime system, e.g. class hierarchy changes. An example is an
// assertion that a given method is not overridden; another example is
// that a type has only one concrete subtype. Compiled code which
// relies on such assertions must be discarded if they are overturned
// by changes in the runtime system. We can think of these assertions
// as approximate invariants, because we expect them to be overturned
// very infrequently. We are willing to perform expensive recovery
// operations when they are overturned. The benefit, of course, is
// performing optimistic optimizations (!) on the object code.
//
// Changes in the class hierarchy due to dynamic linking or
// class evolution can violate dependencies. There is enough
// indexing between classes and nmethods to make dependency
// checking reasonably efficient.
class ciEnv;
class nmethod;
class OopRecorder;
class xmlStream;
class CompileLog;
class DepChange;
class KlassDepChange;
class CallSiteDepChange;
class NoSafepointVerifier;
class Dependencies: public ResourceObj {
public:
// Note: In the comments on dependency types, most uses of the terms
// subtype and supertype are used in a "non-strict" or "inclusive"
// sense, and are starred to remind the reader of this fact.
// Strict uses of the terms use the word "proper".
//
// Specifically, every class is its own subtype* and supertype*.
// (This trick is easier than continually saying things like "Y is a
// subtype of X or X itself".)
//
// Sometimes we write X > Y to mean X is a proper supertype of Y.
// The notation X > {Y, Z} means X has proper subtypes Y, Z.
// The notation X.m > Y means that Y inherits m from X, while
// X.m > Y.m means Y overrides X.m. A star denotes abstractness,
// as *I > A, meaning (abstract) interface I is a super type of A,
// or A.*m > B.m, meaning B.m implements abstract method A.m.
//
// In this module, the terms "subtype" and "supertype" refer to
// Java-level reference type conversions, as detected by
// "instanceof" and performed by "checkcast" operations. The method
// Klass::is_subtype_of tests these relations. Note that "subtype"
// is richer than "subclass" (as tested by Klass::is_subclass_of),
// since it takes account of relations involving interface and array
// types.
//
// To avoid needless complexity, dependencies involving array types
// are not accepted. If you need to make an assertion about an
// array type, make the assertion about its corresponding element
// types. Any assertion that might change about an array type can
// be converted to an assertion about its element type.
//
// Most dependencies are evaluated over a "context type" CX, which
// stands for the set Subtypes(CX) of every Java type that is a subtype*
// of CX. When the system loads a new class or interface N, it is
// responsible for re-evaluating changed dependencies whose context
// type now includes N, that is, all super types of N.
//
enum DepType {
end_marker = 0,
// An 'evol' dependency simply notes that the contents of the
// method were used. If it evolves (is replaced), the nmethod
// must be recompiled. No other dependencies are implied.
evol_method,
FIRST_TYPE = evol_method,
// A context type CX is a leaf it if has no proper subtype.
leaf_type,
// An abstract class CX has exactly one concrete subtype CC.
abstract_with_unique_concrete_subtype,
// The type CX is purely abstract, with no concrete subtype* at all.
abstract_with_no_concrete_subtype,
// The concrete CX is free of concrete proper subtypes.
concrete_with_no_concrete_subtype,
// Given a method M1 and a context class CX, the set MM(CX, M1) of
// "concrete matching methods" in CX of M1 is the set of every
// concrete M2 for which it is possible to create an invokevirtual
// or invokeinterface call site that can reach either M1 or M2.
// That is, M1 and M2 share a name, signature, and vtable index.
// We wish to notice when the set MM(CX, M1) is just {M1}, or
// perhaps a set of two {M1,M2}, and issue dependencies on this.
// The set MM(CX, M1) can be computed by starting with any matching
// concrete M2 that is inherited into CX, and then walking the
// subtypes* of CX looking for concrete definitions.
// 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,
// This dependency asserts when the CallSite.target value changed.
call_site_target_value,
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) & ((~0u) << FIRST_TYPE),
non_klass_types = (1 << call_site_target_value),
klass_types = all_types & ~non_klass_types,
non_ctxk_types = (1 << evol_method) | (1 << call_site_target_value),
implicit_ctxk_types = 0,
explicit_ctxk_types = all_types & ~(non_ctxk_types | implicit_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 bool is_klass_type( DepType dept) { return dept_in_mask(dept, klass_types ); }
static bool has_explicit_context_arg(DepType dept) { return dept_in_mask(dept, explicit_ctxk_types); }
static bool has_implicit_context_arg(DepType dept) { return dept_in_mask(dept, implicit_ctxk_types); }
static int dep_context_arg(DepType dept) { return has_explicit_context_arg(dept) ? 0 : -1; }
static int dep_implicit_context_arg(DepType dept) { return has_implicit_context_arg(dept) ? 0 : -1; }
static void check_valid_dependency_type(DepType dept);
#if INCLUDE_JVMCI
// A Metadata* or object value recorded in an OopRecorder
class DepValue {
private:
// Unique identifier of the value within the associated OopRecorder that
// encodes both the category of the value (0: invalid, positive: metadata, negative: object)
// and the index within a category specific array (metadata: index + 1, object: -(index + 1))
int _id;
public:
DepValue() : _id(0) {}
DepValue(OopRecorder* rec, Metadata* metadata, DepValue* candidate = NULL) {
assert(candidate == NULL || candidate->is_metadata(), "oops");
if (candidate != NULL && candidate->as_metadata(rec) == metadata) {
_id = candidate->_id;
} else {
_id = rec->find_index(metadata) + 1;
}
}
DepValue(OopRecorder* rec, jobject obj, DepValue* candidate = NULL) {
assert(candidate == NULL || candidate->is_object(), "oops");
if (candidate != NULL && candidate->as_object(rec) == obj) {
_id = candidate->_id;
} else {
_id = -(rec->find_index(obj) + 1);
}
}
// Used to sort values in ascending order of index() with metadata values preceding object values
int sort_key() const { return -_id; }
bool operator == (const DepValue& other) const { return other._id == _id; }
bool is_valid() const { return _id != 0; }
int index() const { assert(is_valid(), "oops"); return _id < 0 ? -(_id + 1) : _id - 1; }
bool is_metadata() const { assert(is_valid(), "oops"); return _id > 0; }
bool is_object() const { assert(is_valid(), "oops"); return _id < 0; }
Metadata* as_metadata(OopRecorder* rec) const { assert(is_metadata(), "oops"); return rec->metadata_at(index()); }
Klass* as_klass(OopRecorder* rec) const {
Metadata* m = as_metadata(rec);
assert(m != NULL, "as_metadata returned NULL");
assert(m->is_klass(), "oops");
return (Klass*) m;
}
Method* as_method(OopRecorder* rec) const {
Metadata* m = as_metadata(rec);
assert(m != NULL, "as_metadata returned NULL");
assert(m->is_method(), "oops");
return (Method*) m;
}
jobject as_object(OopRecorder* rec) const { assert(is_object(), "oops"); return rec->oop_at(index()); }
};
#endif // INCLUDE_JVMCI
private:
// State for writing a new set of dependencies:
GrowableArray<int>* _dep_seen; // (seen[h->ident] & (1<<dept))
GrowableArray<ciBaseObject*>* _deps[TYPE_LIMIT];
#if INCLUDE_JVMCI
bool _using_dep_values;
GrowableArray<DepValue>* _dep_values[TYPE_LIMIT];
#endif
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, ciBaseObject* 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;
}
#if INCLUDE_JVMCI
bool note_dep_seen(int dept, DepValue x) {
assert(dept < BitsPerInt, "oops");
// place metadata deps at even indexes, object deps at odd indexes
int x_id = x.is_metadata() ? x.index() * 2 : (x.index() * 2) + 1;
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;
}
#endif
bool maybe_merge_ctxk(GrowableArray<ciBaseObject*>* deps,
int ctxk_i, ciKlass* ctxk);
#if INCLUDE_JVMCI
bool maybe_merge_ctxk(GrowableArray<DepValue>* deps,
int ctxk_i, DepValue ctxk);
#endif
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);
}
#if INCLUDE_JVMCI
Dependencies(Arena* arena, OopRecorder* oop_recorder, CompileLog* log);
#endif
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");
}
static void check_unique_method(ciKlass* ctxk, ciMethod* m) {
assert(!m->can_be_statically_bound(ctxk->as_instance_klass()), "redundant");
}
void assert_common_1(DepType dept, ciBaseObject* x);
void assert_common_2(DepType dept, ciBaseObject* x0, ciBaseObject* x1);
void assert_common_3(DepType dept, ciKlass* ctxk, ciBaseObject* x1, ciBaseObject* 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);
void assert_call_site_target_value(ciCallSite* call_site, ciMethodHandle* method_handle);
#if INCLUDE_JVMCI
private:
static void check_ctxk(Klass* ctxk) {
assert(ctxk->is_instance_klass(), "java types only");
}
static void check_ctxk_abstract(Klass* ctxk) {
check_ctxk(ctxk);
assert(ctxk->is_abstract(), "must be abstract");
}
static void check_unique_method(Klass* ctxk, Method* m) {
assert(!m->can_be_statically_bound(InstanceKlass::cast(ctxk)), "redundant");
}
void assert_common_1(DepType dept, DepValue x);
void assert_common_2(DepType dept, DepValue x0, DepValue x1);
public:
void assert_evol_method(Method* m);
void assert_has_no_finalizable_subclasses(Klass* ctxk);
void assert_leaf_type(Klass* ctxk);
void assert_unique_concrete_method(Klass* ctxk, Method* uniqm);
void assert_abstract_with_unique_concrete_subtype(Klass* ctxk, Klass* conck);
void assert_call_site_target_value(oop callSite, oop methodHandle);
#endif // INCLUDE_JVMCI
// 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(Klass* k); // k is instantiable
static bool is_concrete_method(Method* m, Klass* k); // 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 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 Klass* check_evol_method(Method* m);
static Klass* check_leaf_type(Klass* ctxk);
static Klass* check_abstract_with_unique_concrete_subtype(Klass* ctxk, Klass* conck,
KlassDepChange* changes = NULL);
static Klass* check_abstract_with_no_concrete_subtype(Klass* ctxk,
KlassDepChange* changes = NULL);
static Klass* check_concrete_with_no_concrete_subtype(Klass* ctxk,
KlassDepChange* changes = NULL);
static Klass* check_unique_concrete_method(Klass* ctxk, Method* uniqm,
KlassDepChange* changes = NULL);
static Klass* check_abstract_with_exclusive_concrete_subtypes(Klass* ctxk, Klass* k1, Klass* k2,
KlassDepChange* changes = NULL);
static Klass* check_exclusive_concrete_methods(Klass* ctxk, Method* m1, Method* m2,
KlassDepChange* changes = NULL);
static Klass* check_has_no_finalizable_subclasses(Klass* ctxk, KlassDepChange* changes = NULL);
static Klass* check_call_site_target_value(oop call_site, oop method_handle, CallSiteDepChange* changes = NULL);
// A returned Klass* is NULL if the dependency assertion is still
// valid. A non-NULL Klass* 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 Klass* find_unique_concrete_subtype(Klass* ctxk);
static Method* find_unique_concrete_method(Klass* ctxk, Method* m);
static int find_exclusive_concrete_subtypes(Klass* ctxk, int klen, Klass* k[]);
// 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);
DepType validate_dependencies(CompileTask* task, char** failure_detail = NULL);
void log_all_dependencies();
void log_dependency(DepType dept, GrowableArray<ciBaseObject*>* args) {
ResourceMark rm;
int argslen = args->length();
write_dependency_to(log(), dept, args);
guarantee(argslen == args->length(),
"args array cannot grow inside nested ResoureMark scope");
}
void log_dependency(DepType dept,
ciBaseObject* x0,
ciBaseObject* x1 = NULL,
ciBaseObject* x2 = NULL) {
if (log() == NULL) {
return;
}
ResourceMark rm;
GrowableArray<ciBaseObject*>* ciargs =
new GrowableArray<ciBaseObject*>(dep_args(dept));
assert (x0 != NULL, "no log x0");
ciargs->push(x0);
if (x1 != NULL) {
ciargs->push(x1);
}
if (x2 != NULL) {
ciargs->push(x2);
}
assert(ciargs->length() == dep_args(dept), "");
log_dependency(dept, ciargs);
}
class DepArgument : public ResourceObj {
private:
bool _is_oop;
bool _valid;
void* _value;
public:
DepArgument() : _is_oop(false), _valid(false), _value(NULL) {}
DepArgument(oop v): _is_oop(true), _valid(true), _value(v) {}
DepArgument(Metadata* v): _is_oop(false), _valid(true), _value(v) {}
bool is_null() const { return _value == NULL; }
bool is_oop() const { return _is_oop; }
bool is_metadata() const { return !_is_oop; }
bool is_klass() const { return is_metadata() && metadata_value()->is_klass(); }
bool is_method() const { return is_metadata() && metadata_value()->is_method(); }
oop oop_value() const { assert(_is_oop && _valid, "must be"); return (oop) _value; }
Metadata* metadata_value() const { assert(!_is_oop && _valid, "must be"); return (Metadata*) _value; }
};
static void print_dependency(DepType dept,
GrowableArray<DepArgument>* args,
Klass* witness = NULL, outputStream* st = tty);
private:
// helper for encoding common context types as zero:
static ciKlass* ctxk_encoded_as_null(DepType dept, ciBaseObject* x);
static Klass* ctxk_encoded_as_null(DepType dept, Metadata* x);
static void write_dependency_to(CompileLog* log,
DepType dept,
GrowableArray<ciBaseObject*>* args,
Klass* witness = NULL);
static void write_dependency_to(CompileLog* log,
DepType dept,
GrowableArray<DepArgument>* args,
Klass* witness = NULL);
static void write_dependency_to(xmlStream* xtty,
DepType dept,
GrowableArray<DepArgument>* args,
Klass* witness = NULL);
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 Metadata* recorded_metadata_at(int i);
inline oop recorded_oop_at(int i);
Klass* check_klass_dependency(KlassDepChange* changes);
Klass* check_call_site_dependency(CallSiteDepChange* changes);
void trace_and_log_witness(Klass* witness);
public:
DepStream(Dependencies* deps)
: _code(NULL),
_deps(deps),
_bytes(deps->content_bytes())
{
initial_asserts(deps->size_in_bytes());
}
DepStream(nmethod* code)
: _code(code),
_deps(NULL),
_bytes(code->dependencies_begin())
{
initial_asserts(code->dependencies_size());
}
bool next();
DepType type() { return _type; }
bool is_oop_argument(int i) { return type() == call_site_target_value; }
uintptr_t get_identifier(int i);
int argument_count() { return dep_args(type()); }
int argument_index(int i) { assert(0 <= i && i < argument_count(), "oob");
return _xi[i]; }
Metadata* argument(int i); // => recorded_oop_at(argument_index(i))
oop argument_oop(int i); // => recorded_oop_at(argument_index(i))
Klass* context_type();
bool is_klass_type() { return Dependencies::is_klass_type(type()); }
Method* method_argument(int i) {
Metadata* x = argument(i);
assert(x->is_method(), "type");
return (Method*) x;
}
Klass* type_argument(int i) {
Metadata* x = argument(i);
assert(x->is_klass(), "type");
return (Klass*) x;
}
// The point of the whole exercise: Is this dep still OK?
Klass* check_dependency() {
Klass* result = check_klass_dependency(NULL);
if (result != NULL) return result;
return check_call_site_dependency(NULL);
}
// A lighter version: Checks only around recent changes in a class
// hierarchy. (See Universe::flush_dependents_on.)
Klass* spot_check_dependency_at(DepChange& changes);
// Log the current dependency to xtty or compilation log.
void log_dependency(Klass* witness = NULL);
// Print the current dependency to tty.
void print_dependency(Klass* witness = NULL, bool verbose = false, outputStream* st = tty);
};
friend class Dependencies::DepStream;
static void print_statistics() PRODUCT_RETURN;
};
class DependencySignature : public ResourceObj {
private:
int _args_count;
uintptr_t _argument_hash[Dependencies::max_arg_count];
Dependencies::DepType _type;
public:
DependencySignature(Dependencies::DepStream& dep) {
_args_count = dep.argument_count();
_type = dep.type();
for (int i = 0; i < _args_count; i++) {
_argument_hash[i] = dep.get_identifier(i);
}
}
static bool equals(DependencySignature const& s1, DependencySignature const& s2);
static unsigned hash (DependencySignature const& s1) { return s1.arg(0) >> 2; }
int args_count() const { return _args_count; }
uintptr_t arg(int idx) const { return _argument_hash[idx]; }
Dependencies::DepType type() const { return _type; }
};
// Every particular DepChange is a sub-class of this class.
class DepChange : public StackObj {
public:
// What kind of DepChange is this?
virtual bool is_klass_change() const { return false; }
virtual bool is_call_site_change() const { return false; }
virtual void mark_for_deoptimization(nmethod* nm) = 0;
// Subclass casting with assertions.
KlassDepChange* as_klass_change() {
assert(is_klass_change(), "bad cast");
return (KlassDepChange*) this;
}
CallSiteDepChange* as_call_site_change() {
assert(is_call_site_change(), "bad cast");
return (CallSiteDepChange*) this;
}
void print();
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
};
// Usage:
// for (DepChange::ContextStream str(changes); str.next(); ) {
// Klass* k = str.klass();
// switch (str.change_type()) {
// ...
// }
// }
class ContextStream : public StackObj {
private:
DepChange& _changes;
friend class DepChange;
// iteration variables:
ChangeType _change_type;
Klass* _klass;
Array<InstanceKlass*>* _ti_base; // i.e., transitive_interfaces
int _ti_index;
int _ti_limit;
// start at the beginning:
void start();
public:
ContextStream(DepChange& changes)
: _changes(changes)
{ start(); }
ContextStream(DepChange& changes, NoSafepointVerifier& nsv)
: _changes(changes)
// the nsv argument makes it safe to hold oops like _klass
{ start(); }
bool next();
ChangeType change_type() { return _change_type; }
Klass* klass() { return _klass; }
};
friend class DepChange::ContextStream;
};
// A class hierarchy change coming through the VM (under the Compile_lock).
// The change is structured as a single new type with any number of supers
// and implemented interface types. Other than the new type, any of the
// super types can be context types for a relevant dependency, which the
// new type could invalidate.
class KlassDepChange : public DepChange {
private:
// each change set is rooted in exactly one new type (at present):
Klass* _new_type;
void initialize();
public:
// notes the new type, marks it and all its super-types
KlassDepChange(Klass* new_type)
: _new_type(new_type)
{
initialize();
}
// cleans up the marks
~KlassDepChange();
// What kind of DepChange is this?
virtual bool is_klass_change() const { return true; }
virtual void mark_for_deoptimization(nmethod* nm) {
nm->mark_for_deoptimization(/*inc_recompile_counts=*/true);
}
Klass* new_type() { return _new_type; }
// involves_context(k) is true if k is new_type or any of the super types
bool involves_context(Klass* k);
};
// A CallSite has changed its target.
class CallSiteDepChange : public DepChange {
private:
Handle _call_site;
Handle _method_handle;
public:
CallSiteDepChange(Handle call_site, Handle method_handle);
// What kind of DepChange is this?
virtual bool is_call_site_change() const { return true; }
virtual void mark_for_deoptimization(nmethod* nm) {
nm->mark_for_deoptimization(/*inc_recompile_counts=*/false);
}
oop call_site() const { return _call_site(); }
oop method_handle() const { return _method_handle(); }
};
#endif // SHARE_CODE_DEPENDENCIES_HPP