1 // General object definitions: pointers, reference counting, garbage collection.
7 #include "cln/modules.h"
12 // We don't have to deal with circular structures, so normal reference counting
13 // is sufficient. Is also has the advantage of being mostly non-interrupting.
16 // An object is either a pointer to heap allocated data
19 // It is possible to distinguish these because pointers are aligned.
20 // cl_word_alignment is the guaranteed alignment of a `void*' or `long'
21 // in memory. Must be > 1.
23 #define cl_word_alignment 2
25 #if defined(__i386__) || (defined(__mips__) && !defined(__LP64__)) || (defined(__sparc__) && !defined(__arch64__)) || defined(__hppa__) || defined(__arm__) || defined(__rs6000__) || defined(__m88k__) || defined(__convex__) || (defined(__s390__) && !defined(__s390x__)) || defined(__sh__) || (defined(__x86_64__) && defined(__ILP32__))
26 #define cl_word_alignment 4
28 #if defined(__alpha__) || defined(__ia64__) || defined(__mips64__) || defined(__powerpc64__) || (defined(__sparc__) && defined(__arch64__)) || (defined(__x86_64__) && !defined(__ILP32__)) || defined(__s390x__) || defined(__aarch64__)
29 #define cl_word_alignment 8
31 #if !defined(cl_word_alignment)
32 #error "Define cl_word_alignment for your CPU!"
36 // Four basic classes are introduced:
40 // gcpointer rcpointer
42 // `gcobject' = garbage collectible object (pointer or immediate),
43 // `gcpointer' = garbage collectible pointer,
44 // `rcobject' = reference counted object (pointer or immediate),
45 // `rcpointer' = reference counted pointer.
47 // "garbage collectible" means that a reference count is maintained, and
48 // when the reference count drops to 0, the object is freed. This is useful
49 // for all kind of short- or long-lived objects.
50 // "reference counted" means that a reference count is maintained, which
51 // cannot drop to 0. This is useful for objects which are registered in a
52 // global cache table, in order to know which objects can be thrown away
53 // when the cache is cleaned. (If the cache were never cleaned, its objects
54 // would never be freed, and we could get away with normal C pointers.)
56 // It is permissible to treat a `rcobject' as a `gcobject', and a `rcpointer'
57 // as a `gcpointer', but this just increases the destructor and copy-constructor
59 // It is also permissible to treat a `gcpointer' as a `gcobject', and a
60 // `rcpointer' as a `rcobject', but this just increases the destructor and
61 // copy-constructor overhead.
64 // Immediate data is a word, as wide as a pointer.
65 typedef sintP cl_sint;
66 typedef uintP cl_uint; // This ought to be called `cl_word'.
67 #define cl_pointer_size intPsize
68 // NB: (cl_pointer_size==64) implies defined(HAVE_FAST_LONGLONG)
69 #if (cl_pointer_size==64)
70 #define CL_WIDE_POINTERS
73 // Distinguish immediate data from pointers.
74 inline bool cl_pointer_p (cl_uint word)
76 return (word & (cl_word_alignment-1)) == 0;
78 inline bool cl_immediate_p (cl_uint word)
80 return (word & (cl_word_alignment-1)) != 0;
83 // Immediate data: Fixnum, Short Float, maybe Single Float.
84 // They have type tags.
85 // |...............................|......|
88 // Number of bits reserved for tagging information:
89 #if (cl_word_alignment <= 4)
94 #define cl_tag_shift 0
95 #define cl_value_shift (cl_tag_len+cl_tag_shift)
96 #define cl_value_len (cl_pointer_size - cl_value_shift)
97 #define cl_tag_mask (((1UL << cl_tag_len) - 1) << cl_tag_shift)
98 #define cl_value_mask (((1UL << cl_value_len) - 1) << cl_value_shift)
100 // Return the tag of a word.
101 inline cl_uint cl_tag (cl_uint word)
103 return (word & cl_tag_mask) >> cl_tag_shift;
106 // Return the value (unsigned) of a word.
107 inline cl_uint cl_value (cl_uint word)
109 // This assumes cl_value_shift + cl_value_len == cl_pointer_size.
110 return word >> cl_value_shift;
113 // Return a word, combining a value and a tag.
114 inline cl_uint cl_combine (cl_uint tag, cl_uint value)
116 return (value << cl_value_shift) + (tag << cl_tag_shift);
118 inline cl_uint cl_combine (cl_uint tag, cl_sint value)
120 // This assumes cl_value_shift + cl_value_len == cl_pointer_size.
121 return (value << cl_value_shift) + (tag << cl_tag_shift);
123 // Keep the compiler happy.
124 inline cl_uint cl_combine (cl_uint tag, unsigned int value)
125 { return cl_combine(tag, (cl_uint)value); }
126 inline cl_uint cl_combine (cl_uint tag, int value)
127 { return cl_combine(tag, (cl_sint)value); }
129 inline cl_uint cl_combine (cl_uint tag, unsigned long long value)
130 { return cl_combine(tag, (cl_uint)value); }
131 inline cl_uint cl_combine (cl_uint tag, long long value)
132 { return cl_combine(tag, (cl_uint)value); }
135 // Definition of the tags.
136 #if !defined(CL_WIDE_POINTERS)
137 #if (cl_word_alignment == 2)
139 #define cl_SF_tag 3 // must satisfy the cl_immediate_p predicate!
141 #if (cl_word_alignment == 4)
145 #else // CL_WIDE_POINTERS
146 // Single Floats are immediate as well.
152 // Corresponding classes.
153 extern const struct cl_class * cl_immediate_classes [1<<cl_tag_len];
156 // Heap allocated data contains a header, for two purposes:
158 // - reference count (a portable alternative to garbage collection,
159 // or the basis for a portable and interoperable garbage collection).
161 int refcount; // reference count
162 const struct cl_class * type; // type tag
165 // Function to destroy the contents of a heap object.
166 typedef void (*cl_heap_destructor_function) (cl_heap* pointer);
167 // Flags, may be ORed together.
168 #define cl_class_flags_subclass_complex 1 // all instances belong to cl_N
169 #define cl_class_flags_subclass_real 2 // all instances belong to cl_R
170 #define cl_class_flags_subclass_float 4 // all instances belong to cl_F
171 #define cl_class_flags_subclass_rational 8 // all instances belong to cl_RA
172 #define cl_class_flags_number_ring 16 // all instances are rings whose
173 // elements belong to cl_number
174 #define cl_class_flags_modint_ring 32 // all instances are rings whose
175 // elements belong to cl_MI
176 #define cl_class_flags_univpoly_ring 64 // all instances are rings whose
177 // elements belong to cl_UP
178 // Function to print an object for debugging, to cerr.
179 typedef void (*cl_heap_dprint_function) (cl_heap* pointer);
182 cl_heap_destructor_function destruct;
184 cl_heap_dprint_function dprint;
187 // Free an object on heap.
188 extern void cl_free_heap_object (cl_heap* pointer);
190 // Debugging support for dynamic typing: Register a debugging print function.
191 #define cl_register_type_printer(type,printer) \
192 { extern cl_class type; type.dprint = (printer); }
195 // cl_private_thing: An immediate value or a pointer into the heap.
196 // This must be as wide as a `cl_uint'.
197 // (Actually, this ought to be a union { void*; cl_uint; }, but using
198 // a pointer type generates better code.)
199 // Never throw away a cl_private_thing, or reference counts will be wrong!
200 typedef struct cl_anything * cl_private_thing;
202 // Increment the reference count.
203 inline void cl_inc_pointer_refcount (cl_heap* pointer)
208 // Decrement the reference count of a garbage collected pointer.
209 inline void cl_gc_dec_pointer_refcount (cl_heap* pointer)
211 if (--pointer->refcount == 0)
212 cl_free_heap_object(pointer);
214 // Decrement the reference count of a reference counted pointer.
215 inline void cl_rc_dec_pointer_refcount (cl_heap* pointer)
220 // Increment the reference count.
221 // This must be a macro, not an inline function, because pointer_p() and
222 // inc_pointer_refcount() are non-virtual member functions, so that the
223 // compiler can optimize it.
224 #define cl_inc_refcount(x) \
225 if ((x).pointer_p()) \
226 (x).inc_pointer_refcount(); \
228 // Decrement the reference count.
229 // This must be a macro, not an inline function, because pointer_p() and
230 // dec_pointer_refcount() are non-virtual member functions, so that the
231 // compiler can optimize it.
232 #define cl_dec_refcount(x) \
233 if ((x).pointer_p()) \
234 (x).dec_pointer_refcount(); \
236 // The declaration of a copy constructor.
237 // Restriction: The base class's default constructor must do nothing or
238 // initialize `pointer' to a constant expression.
239 #define CL_DEFINE_COPY_CONSTRUCTOR1(_class_) \
240 _CL_DEFINE_COPY_CONSTRUCTOR1(_class_,_class_)
241 #define _CL_DEFINE_COPY_CONSTRUCTOR1(_class_,_classname_) \
242 inline _class_::_classname_ (const _class_& x) \
244 cl_uint x_word = x.word; \
245 cl_inc_refcount(x); \
246 this->word = x_word; \
249 // The declaration of a copy constructor.
250 // Restriction: The base class must have the usual `cl_private_thing'
251 // constructor. Drawback: The base class must be known here.
252 #define CL_DEFINE_COPY_CONSTRUCTOR2(_class_,_baseclass_) \
253 _CL_DEFINE_COPY_CONSTRUCTOR2(_class_,_class_,_baseclass_)
254 #define _CL_DEFINE_COPY_CONSTRUCTOR2(_class_,_classname_,_baseclass_) \
255 inline _class_::_classname_ (const _class_& x) \
256 : _baseclass_ (as_cl_private_thing(x)) {}
258 // The declaration of an assignment operator.
259 #define CL_DEFINE_ASSIGNMENT_OPERATOR(dest_class,src_class) \
260 inline dest_class& dest_class::operator= (const src_class& x) \
262 /* Be careful, we might be assigning x to itself. */ \
263 cl_uint x_word = x.word; \
264 cl_inc_refcount(x); \
265 cl_dec_refcount(*this); \
266 this->word = x_word; \
270 // We have a small problem with destructors: The specialized destructor
271 // of a leaf class such as `cl_SF' should be more efficient than the
272 // general destructor for `cl_N'. Since (by C++ specs) destructing a cl_SF
273 // would run the destructors for cl_SF, cl_F, cl_R, cl_N (in that order),
274 // and in the last step the compiler does not know any more that the object
275 // actually is a cl_SF, there is no way to optimize the destructor!
276 // ("progn-reversed" method combination is evil.)
277 // And if we define "mirror"/"shadow" classes with no destructors (such
278 // that `cl_F' inherits from `cl_F_no_destructor' buts adds a destructor)
279 // then we need to add explicit conversion operators cl_SF -> cl_F -> cl_R ...,
280 // with the effect that calling an overloaded function like `as_cl_F'
281 // (which has two signatures `as_cl_F(cl_number)' and `as_cl_F(cl_F)')
282 // with a cl_SF argument gives an "call of overloaded function is ambiguous"
284 // There is no help: If we want overloaded functions to be callable in a way
285 // that makes sense, `cl_SF' has to be a subclass of `cl_F', and then the
286 // destructor of `cl_SF' will do at least as much computation as the `cl_F'
287 // destructor. Praise C++ ! :-((
288 // (Even making `pointer_p()' a virtual function would not help.)
291 // This is obnoxious.
292 template <class key1_type, class value_type> struct cl_htentry1;
294 // The four concrete classes of all objects.
300 cl_heap* heappointer;
304 // Default constructor. (Used for objects with no initializer.)
306 // Destructor. (Used when a variable goes out of scope.)
309 cl_gcobject (const cl_gcobject&);
310 // Assignment operator.
311 cl_gcobject& operator= (const cl_gcobject&);
312 // Distinguish immediate data from pointer.
313 bool pointer_p() const
314 { return cl_pointer_p(word); }
315 // Reference counting.
316 void inc_pointer_refcount () const
317 { cl_inc_pointer_refcount(heappointer); }
318 void dec_pointer_refcount () const
319 { cl_gc_dec_pointer_refcount(heappointer); }
320 // Return the type tag of an immediate number.
321 cl_uint nonpointer_tag () const
322 { return cl_tag(word); }
323 // Return the type tag of a heap-allocated number.
324 const cl_class * pointer_type () const
325 { return heappointer->type; }
326 // Private pointer manipulations.
327 cl_private_thing _as_cl_private_thing () const;
328 // Private constructor.
329 cl_gcobject (cl_private_thing p)
332 void debug_print () const;
333 // Ability to place an object at a given address.
334 void* operator new (size_t size, void* ptr) { (void)size; return ptr; }
335 void* operator new (size_t size) { return ::operator new (size); }
337 inline cl_gcobject::cl_gcobject () {}
338 inline cl_gcobject::~cl_gcobject () { cl_dec_refcount(*this); }
339 CL_DEFINE_COPY_CONSTRUCTOR1(cl_gcobject)
340 CL_DEFINE_ASSIGNMENT_OPERATOR(cl_gcobject,cl_gcobject)
346 cl_heap* heappointer;
350 // Default constructor. (Used for objects with no initializer.)
352 // Destructor. (Used when a variable goes out of scope.)
355 cl_gcpointer (const cl_gcpointer&);
356 // Assignment operator.
357 cl_gcpointer& operator= (const cl_gcpointer&);
358 // Distinguish immediate data from pointer.
359 bool pointer_p() const
361 // Reference counting.
362 void inc_pointer_refcount () const
363 { cl_inc_pointer_refcount(heappointer); }
364 void dec_pointer_refcount () const
365 { cl_gc_dec_pointer_refcount(heappointer); }
366 // Return the type tag of an immediate number.
367 cl_uint nonpointer_tag () const
368 { return cl_tag(word); }
369 // Return the type tag of a heap-allocated number.
370 const cl_class * pointer_type () const
371 { return heappointer->type; }
372 // Private pointer manipulations.
373 cl_private_thing _as_cl_private_thing () const;
374 // Private constructor.
375 cl_gcpointer (cl_private_thing p)
378 void debug_print () const;
379 // Ability to place an object at a given address.
380 void* operator new (size_t size, void* ptr) { (void)size; return ptr; }
381 void* operator new (size_t size) { return ::operator new (size); }
383 inline cl_gcpointer::cl_gcpointer () {}
384 inline cl_gcpointer::~cl_gcpointer () { cl_dec_refcount(*this); }
385 CL_DEFINE_COPY_CONSTRUCTOR1(cl_gcpointer)
386 CL_DEFINE_ASSIGNMENT_OPERATOR(cl_gcpointer,cl_gcpointer)
392 cl_heap* heappointer;
396 // Default constructor. (Used for objects with no initializer.)
398 // Destructor. (Used when a variable goes out of scope.)
401 cl_rcobject (const cl_rcobject&);
402 // Assignment operator.
403 cl_rcobject& operator= (const cl_rcobject&);
404 // Distinguish immediate data from pointer.
405 bool pointer_p() const
406 { return cl_pointer_p(word); }
407 // Reference counting.
408 void inc_pointer_refcount () const
409 { cl_inc_pointer_refcount(heappointer); }
410 void dec_pointer_refcount () const
411 { cl_rc_dec_pointer_refcount(heappointer); }
412 // Return the type tag of an immediate number.
413 cl_uint nonpointer_tag () const
414 { return cl_tag(word); }
415 // Return the type tag of a heap-allocated number.
416 const cl_class * pointer_type () const
417 { return heappointer->type; }
418 // Private pointer manipulations.
419 cl_private_thing _as_cl_private_thing () const;
420 // Private constructor.
421 cl_rcobject (cl_private_thing p)
424 void debug_print () const;
425 // Ability to place an object at a given address.
426 void* operator new (size_t size, void* ptr) { (void)size; return ptr; }
427 void* operator new (size_t size) { return ::operator new (size); }
429 inline cl_rcobject::cl_rcobject () {}
430 inline cl_rcobject::~cl_rcobject () { cl_dec_refcount(*this); }
431 CL_DEFINE_COPY_CONSTRUCTOR1(cl_rcobject)
432 CL_DEFINE_ASSIGNMENT_OPERATOR(cl_rcobject,cl_rcobject)
438 cl_heap* heappointer;
442 // Default constructor. (Used for objects with no initializer.)
444 // Destructor. (Used when a variable goes out of scope.)
447 cl_rcpointer (const cl_rcpointer&);
448 // Assignment operator.
449 cl_rcpointer& operator= (const cl_rcpointer&);
450 // Distinguish immediate data from pointer.
451 bool pointer_p() const
453 // Reference counting.
454 void inc_pointer_refcount () const
455 { cl_inc_pointer_refcount(heappointer); }
456 void dec_pointer_refcount () const
457 { cl_rc_dec_pointer_refcount(heappointer); }
458 // Return the type tag of an immediate number.
459 cl_uint nonpointer_tag () const
460 { return cl_tag(word); }
461 // Return the type tag of a heap-allocated number.
462 const cl_class * pointer_type () const
463 { return heappointer->type; }
464 // Private pointer manipulations.
465 cl_private_thing _as_cl_private_thing () const;
466 // Private constructor.
467 cl_rcpointer (cl_private_thing p)
470 void debug_print () const;
471 // Ability to place an object at a given address.
472 void* operator new (size_t size, void* ptr) { (void)size; return ptr; }
473 void* operator new (size_t size) { return ::operator new (size); }
475 inline cl_rcpointer::cl_rcpointer () {}
476 inline cl_rcpointer::~cl_rcpointer () { cl_dec_refcount(*this); }
477 CL_DEFINE_COPY_CONSTRUCTOR1(cl_rcpointer)
478 CL_DEFINE_ASSIGNMENT_OPERATOR(cl_rcpointer,cl_rcpointer)
480 // Private pointer manipulations.
482 inline cl_private_thing cl_gcobject::_as_cl_private_thing () const
484 cl_private_thing p = (cl_private_thing) pointer;
485 cl_inc_refcount(*this);
488 inline cl_private_thing as_cl_private_thing (const cl_gcobject& x)
490 return x._as_cl_private_thing();
493 inline cl_private_thing cl_gcpointer::_as_cl_private_thing () const
495 cl_private_thing p = (cl_private_thing) pointer;
496 cl_inc_refcount(*this);
499 inline cl_private_thing as_cl_private_thing (const cl_gcpointer& x)
501 return x._as_cl_private_thing();
504 inline cl_private_thing cl_rcobject::_as_cl_private_thing () const
506 cl_private_thing p = (cl_private_thing) pointer;
507 cl_inc_refcount(*this);
510 inline cl_private_thing as_cl_private_thing (const cl_rcobject& x)
512 return x._as_cl_private_thing();
515 inline cl_private_thing cl_rcpointer::_as_cl_private_thing () const
517 cl_private_thing p = (cl_private_thing) pointer;
518 cl_inc_refcount(*this);
521 inline cl_private_thing as_cl_private_thing (const cl_rcpointer& x)
523 return x._as_cl_private_thing();
526 // Note: When we define a function that returns a class object by value,
527 // we normally return it as const value. The declarations
530 // const T func (...); (B)
531 // behave identically and generate identical code, except that the code
533 // compiles fine with (A) but is an error (and yields a warning) with (B).
534 // We want this warning.
536 // Define a conversion operator from one object to another object of the
538 #define CL_DEFINE_CONVERTER(target_class) \
539 operator const target_class & () const \
541 typedef int assert1 [2*(sizeof(target_class)==sizeof(*this))-1]; \
542 return * (const target_class *) (void*) this; \
547 #endif /* _CL_OBJECT_H */