graal-compiler: src/share/vm/code/dependencies.hpp comparison

comparison src/share/vm/code/dependencies.hpp @ 0:a61af66fc99e jdk7-b24

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author	duke
date	Sat, 01 Dec 2007 00:00:00 +0000
parents
children	167c2986d91b

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+:a61af66fc99e
+/*
+* Copyright 2005-2006 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+* CA 95054 USA or visit www.sun.com if you need additional information or
+* have any questions.
+*
+*/
+//** Dependencies represent assertions (approximate invariants) within
+// the class hierarchy.  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 class hierarchy.  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 No_Safepoint_Verifier;
+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,
+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;
+};
+// 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 DepChange : public StackObj {
+private:
+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
+};
+// 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;
+}
+ContextStream(DepChange& changes)
+: _changes(changes)
+{ start(); }
+public:
+ContextStream(DepChange& changes, No_Safepoint_Verifier& nsv)
+: _changes(changes)
+// the nsv argument makes it safe to hold oops like _klass
+{ start(); }
+bool next();
+klassOop   klass()           { return _klass; }
+};
+friend class DepChange::ContextStream;
+void print();
+};

Mercurial > hg > graal-compiler

comparison src/share/vm/code/dependencies.hpp @ 0:a61af66fc99e jdk7-b24