1 #ifdef USE_PRAGMA_IDENT_HDR
2 #pragma ident "@(#)relocInfo.hpp 1.87 07/06/19 09:08:11 JVM"
3 #endif
4 /*
5 * Copyright 1997-2006 Sun Microsystems, Inc. All Rights Reserved.
6 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
7 *
8 * This code is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License version 2 only, as
10 * published by the Free Software Foundation.
11 *
12 * This code is distributed in the hope that it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 * version 2 for more details (a copy is included in the LICENSE file that
16 * accompanied this code).
17 *
18 * You should have received a copy of the GNU General Public License version
19 * 2 along with this work; if not, write to the Free Software Foundation,
20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
21 *
22 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
23 * CA 95054 USA or visit www.sun.com if you need additional information or
24 * have any questions.
25 *
26 */
27
28 // Types in this file:
29 // relocInfo
30 // One element of an array of halfwords encoding compressed relocations.
31 // Also, the source of relocation types (relocInfo::oop_type, ...).
32 // Relocation
33 // A flyweight object representing a single relocation.
34 // It is fully unpacked from the compressed relocation array.
35 // oop_Relocation, ... (subclasses of Relocation)
36 // The location of some type-specific operations (oop_addr, ...).
37 // Also, the source of relocation specs (oop_Relocation::spec, ...).
38 // RelocationHolder
39 // A ValueObj type which acts as a union holding a Relocation object.
40 // Represents a relocation spec passed into a CodeBuffer during assembly.
41 // RelocIterator
42 // A StackObj which iterates over the relocations associated with
43 // a range of code addresses. Can be used to operate a copy of code.
44 // PatchingRelocIterator
45 // Specialized subtype of RelocIterator which removes breakpoints
46 // temporarily during iteration, then restores them.
47 // BoundRelocation
48 // An _internal_ type shared by packers and unpackers of relocations.
49 // It pastes together a RelocationHolder with some pointers into
50 // code and relocInfo streams.
51
52
53 // Notes on relocType:
54 //
55 // These hold enough information to read or write a value embedded in
56 // the instructions of an CodeBlob. They're used to update:
57 //
58 // 1) embedded oops (isOop() == true)
59 // 2) inline caches (isIC() == true)
60 // 3) runtime calls (isRuntimeCall() == true)
61 // 4) internal word ref (isInternalWord() == true)
62 // 5) external word ref (isExternalWord() == true)
63 //
64 // when objects move (GC) or if code moves (compacting the code heap).
65 // They are also used to patch the code (if a call site must change)
66 //
67 // A relocInfo is represented in 16 bits:
68 // 4 bits indicating the relocation type
69 // 12 bits indicating the offset from the previous relocInfo address
70 //
71 // The offsets accumulate along the relocInfo stream to encode the
72 // address within the CodeBlob, which is named RelocIterator::addr().
73 // The address of a particular relocInfo always points to the first
74 // byte of the relevant instruction (and not to any of its subfields
75 // or embedded immediate constants).
76 //
77 // The offset value is scaled appropriately for the target machine.
78 // (See relocInfo_<arch>.hpp for the offset scaling.)
79 //
80 // On some machines, there may also be a "format" field which may provide
81 // additional information about the format of the instruction stream
82 // at the corresponding code address. The format value is usually zero.
83 // Any machine (such as Intel) whose instructions can sometimes contain
84 // more than one relocatable constant needs format codes to distinguish
85 // which operand goes with a given relocation.
86 //
87 // If the target machine needs N format bits, the offset has 12-N bits,
88 // the format is encoded between the offset and the type, and the
89 // relocInfo_<arch>.hpp file has manifest constants for the format codes.
90 //
91 // If the type is "data_prefix_tag" then the offset bits are further encoded,
92 // and in fact represent not a code-stream offset but some inline data.
93 // The data takes the form of a counted sequence of halfwords, which
94 // precedes the actual relocation record. (Clients never see it directly.)
95 // The interpetation of this extra data depends on the relocation type.
96 //
97 // On machines that have 32-bit immediate fields, there is usually
98 // little need for relocation "prefix" data, because the instruction stream
99 // is a perfectly reasonable place to store the value. On machines in
100 // which 32-bit values must be "split" across instructions, the relocation
101 // data is the "true" specification of the value, which is then applied
102 // to some field of the instruction (22 or 13 bits, on SPARC).
103 //
104 // Whenever the location of the CodeBlob changes, any PC-relative
105 // relocations, and any internal_word_type relocations, must be reapplied.
106 // After the GC runs, oop_type relocations must be reapplied.
107 //
108 //
109 // Here are meanings of the types:
110 //
111 // relocInfo::none -- a filler record
112 // Value: none
113 // Instruction: The corresponding code address is ignored
114 // Data: Any data prefix and format code are ignored
115 // (This means that any relocInfo can be disabled by setting
116 // its type to none. See relocInfo::remove.)
117 //
118 // relocInfo::oop_type -- a reference to an oop
119 // Value: an oop, or else the address (handle) of an oop
120 // Instruction types: memory (load), set (load address)
121 // Data: [] an oop stored in 4 bytes of instruction
122 // [n] n is the index of an oop in the CodeBlob's oop pool
123 // [[N]n l] and l is a byte offset to be applied to the oop
124 // [Nn Ll] both index and offset may be 32 bits if necessary
125 // Here is a special hack, used only by the old compiler:
126 // [[N]n 00] the value is the __address__ of the nth oop in the pool
127 // (Note that the offset allows optimal references to class variables.)
128 //
129 // relocInfo::internal_word_type -- an address within the same CodeBlob
130 // relocInfo::section_word_type -- same, but can refer to another section
131 // Value: an address in the CodeBlob's code or constants section
132 // Instruction types: memory (load), set (load address)
133 // Data: [] stored in 4 bytes of instruction
134 // [[L]l] a relative offset (see [About Offsets] below)
135 // In the case of section_word_type, the offset is relative to a section
136 // base address, and the section number (e.g., SECT_INSTS) is encoded
137 // into the low two bits of the offset L.
138 //
139 // relocInfo::external_word_type -- a fixed address in the runtime system
140 // Value: an address
141 // Instruction types: memory (load), set (load address)
142 // Data: [] stored in 4 bytes of instruction
143 // [n] the index of a "well-known" stub (usual case on RISC)
144 // [Ll] a 32-bit address
145 //
146 // relocInfo::runtime_call_type -- a fixed subroutine in the runtime system
147 // Value: an address
148 // Instruction types: PC-relative call (or a PC-relative branch)
149 // Data: [] stored in 4 bytes of instruction
150 //
151 // relocInfo::static_call_type -- a static call
152 // Value: an CodeBlob, a stub, or a fixup routine
153 // Instruction types: a call
154 // Data: []
155 // The identity of the callee is extracted from debugging information.
156 // //%note reloc_3
157 //
158 // relocInfo::virtual_call_type -- a virtual call site (which includes an inline
159 // cache)
160 // Value: an CodeBlob, a stub, the interpreter, or a fixup routine
161 // Instruction types: a call, plus some associated set-oop instructions
162 // Data: [] the associated set-oops are adjacent to the call
163 // [n] n is a relative offset to the first set-oop
164 // [[N]n l] and l is a limit within which the set-oops occur
165 // [Nn Ll] both n and l may be 32 bits if necessary
166 // The identity of the callee is extracted from debugging information.
167 //
168 // relocInfo::opt_virtual_call_type -- a virtual call site that is statically bound
169 //
170 // Same info as a static_call_type. We use a special type, so the handling of
171 // virtuals and statics are separated.
172 //
173 //
174 // The offset n points to the first set-oop. (See [About Offsets] below.)
175 // In turn, the set-oop instruction specifies or contains an oop cell devoted
176 // exclusively to the IC call, which can be patched along with the call.
177 //
178 // The locations of any other set-oops are found by searching the relocation
179 // information starting at the first set-oop, and continuing until all
180 // relocations up through l have been inspected. The value l is another
181 // relative offset. (Both n and l are relative to the call's first byte.)
182 //
183 // The limit l of the search is exclusive. However, if it points within
184 // the call (e.g., offset zero), it is adjusted to point after the call and
185 // any associated machine-specific delay slot.
186 //
187 // Since the offsets could be as wide as 32-bits, these conventions
188 // put no restrictions whatever upon code reorganization.
189 //
190 // The compiler is responsible for ensuring that transition from a clean
191 // state to a monomorphic compiled state is MP-safe. This implies that
192 // the system must respond well to intermediate states where a random
193 // subset of the set-oops has been correctly from the clean state
194 // upon entry to the VEP of the compiled method. In the case of a
195 // machine (Intel) with a single set-oop instruction, the 32-bit
196 // immediate field must not straddle a unit of memory coherence.
197 // //%note reloc_3
198 //
199 // relocInfo::breakpoint_type -- a conditional breakpoint in the code
200 // Value: none
201 // Instruction types: any whatsoever
202 // Data: [b [T]t i...]
203 // The b is a bit-packed word representing the breakpoint's attributes.
204 // The t is a target address which the breakpoint calls (when it is enabled).
205 // The i... is a place to store one or two instruction words overwritten
206 // by a trap, so that the breakpoint may be subsequently removed.
207 //
208 // relocInfo::static_stub_type -- an extra stub for each static_call_type
209 // Value: none
210 // Instruction types: a virtual call: { set_oop; jump; }
211 // Data: [[N]n] the offset of the associated static_call reloc
212 // This stub becomes the target of a static call which must be upgraded
213 // to a virtual call (because the callee is interpreted).
214 // See [About Offsets] below.
215 // //%note reloc_2
216 //
217 // For example:
218 //
219 // INSTRUCTIONS RELOC: TYPE PREFIX DATA
220 // ------------ ---- -----------
221 // sethi %hi(myObject), R oop_type [n(myObject)]
222 // ld [R+%lo(myObject)+fldOffset], R2 oop_type [n(myObject) fldOffset]
223 // add R2, 1, R2
224 // st R2, [R+%lo(myObject)+fldOffset] oop_type [n(myObject) fldOffset]
225 //%note reloc_1
226 //
227 // This uses 4 instruction words, 8 relocation halfwords,
228 // and an entry (which is sharable) in the CodeBlob's oop pool,
229 // for a total of 36 bytes.
230 //
231 // Note that the compiler is responsible for ensuring the "fldOffset" when
232 // added to "%lo(myObject)" does not overflow the immediate fields of the
233 // memory instructions.
234 //
235 //
236 // [About Offsets] Relative offsets are supplied to this module as
237 // positive byte offsets, but they may be internally stored scaled
238 // and/or negated, depending on what is most compact for the target
239 // system. Since the object pointed to by the offset typically
240 // precedes the relocation address, it is profitable to store
241 // these negative offsets as positive numbers, but this decision
242 // is internal to the relocation information abstractions.
243 //
244
245 class Relocation;
246 class CodeBuffer;
247 class CodeSection;
248 class RelocIterator;
249
250 class relocInfo VALUE_OBJ_CLASS_SPEC {
251 friend class RelocIterator;
252 public:
253 enum relocType {
254 none = 0, // Used when no relocation should be generated
255 oop_type = 1, // embedded oop
256 virtual_call_type = 2, // a standard inline cache call for a virtual send
257 opt_virtual_call_type = 3, // a virtual call that has been statically bound (i.e., no IC cache)
258 static_call_type = 4, // a static send
259 static_stub_type = 5, // stub-entry for static send (takes care of interpreter case)
260 runtime_call_type = 6, // call to fixed external routine
261 external_word_type = 7, // reference to fixed external address
262 internal_word_type = 8, // reference within the current code blob
263 section_word_type = 9, // internal, but a cross-section reference
264 poll_type = 10, // polling instruction for safepoints
265 poll_return_type = 11, // polling instruction for safepoints at return
266 breakpoint_type = 12, // an initialization barrier or safepoint
267 yet_unused_type = 13, // Still unused
268 yet_unused_type_2 = 14, // Still unused
269 data_prefix_tag = 15, // tag for a prefix (carries data arguments)
270 type_mask = 15 // A mask which selects only the above values
271 };
272
273 protected:
274 unsigned short _value;
275
276 enum RawBitsToken { RAW_BITS };
277 relocInfo(relocType type, RawBitsToken ignore, int bits)
278 : _value((type << nontype_width) + bits) { }
279
280 relocInfo(relocType type, RawBitsToken ignore, int off, int f)
281 : _value((type << nontype_width) + (off / (unsigned)offset_unit) + (f << offset_width)) { }
282
283 public:
284 // constructor
285 relocInfo(relocType type, int offset, int format = 0)
286 #ifndef ASSERT
287 {
288 (*this) = relocInfo(type, RAW_BITS, offset, format);
289 }
290 #else
291 // Put a bunch of assertions out-of-line.
292 ;
293 #endif
294
295 #define APPLY_TO_RELOCATIONS(visitor) \
296 visitor(oop) \
297 visitor(virtual_call) \
298 visitor(opt_virtual_call) \
299 visitor(static_call) \
300 visitor(static_stub) \
301 visitor(runtime_call) \
302 visitor(external_word) \
303 visitor(internal_word) \
304 visitor(poll) \
305 visitor(poll_return) \
306 visitor(breakpoint) \
307 visitor(section_word) \
308
309
310 public:
311 enum {
312 value_width = sizeof(unsigned short) * BitsPerByte,
313 type_width = 4, // == log2(type_mask+1)
314 nontype_width = value_width - type_width,
315 datalen_width = nontype_width-1,
316 datalen_tag = 1 << datalen_width, // or-ed into _value
317 datalen_limit = 1 << datalen_width,
318 datalen_mask = (1 << datalen_width)-1
319 };
320
321 // accessors
322 public:
323 relocType type() const { return (relocType)((unsigned)_value >> nontype_width); }
324 int format() const { return format_mask==0? 0: format_mask &
325 ((unsigned)_value >> offset_width); }
326 int addr_offset() const { assert(!is_prefix(), "must have offset");
327 return (_value & offset_mask)*offset_unit; }
328
329 protected:
330 const short* data() const { assert(is_datalen(), "must have data");
331 return (const short*)(this + 1); }
332 int datalen() const { assert(is_datalen(), "must have data");
333 return (_value & datalen_mask); }
334 int immediate() const { assert(is_immediate(), "must have immed");
335 return (_value & datalen_mask); }
336 public:
337 static int addr_unit() { return offset_unit; }
338 static int offset_limit() { return (1 << offset_width) * offset_unit; }
339
340 void set_type(relocType type);
341 void set_format(int format);
342
343 void remove() { set_type(none); }
344
345 protected:
346 bool is_none() const { return type() == none; }
347 bool is_prefix() const { return type() == data_prefix_tag; }
348 bool is_datalen() const { assert(is_prefix(), "must be prefix");
349 return (_value & datalen_tag) != 0; }
350 bool is_immediate() const { assert(is_prefix(), "must be prefix");
351 return (_value & datalen_tag) == 0; }
352
353 public:
354 // Occasionally records of type relocInfo::none will appear in the stream.
355 // We do not bother to filter these out, but clients should ignore them.
356 // These records serve as "filler" in three ways:
357 // - to skip large spans of unrelocated code (this is rare)
358 // - to pad out the relocInfo array to the required oop alignment
359 // - to disable old relocation information which is no longer applicable
360
361 inline friend relocInfo filler_relocInfo();
362
363 // Every non-prefix relocation may be preceded by at most one prefix,
364 // which supplies 1 or more halfwords of associated data. Conventionally,
365 // an int is represented by 0, 1, or 2 halfwords, depending on how
366 // many bits are required to represent the value. (In addition,
367 // if the sole halfword is a 10-bit unsigned number, it is made
368 // "immediate" in the prefix header word itself. This optimization
369 // is invisible outside this module.)
370
371 inline friend relocInfo prefix_relocInfo(int datalen = 0);
372
373 protected:
374 // an immediate relocInfo optimizes a prefix with one 10-bit unsigned value
375 static relocInfo immediate_relocInfo(int data0) {
376 assert(fits_into_immediate(data0), "data0 in limits");
377 return relocInfo(relocInfo::data_prefix_tag, RAW_BITS, data0);
378 }
379 static bool fits_into_immediate(int data0) {
380 return (data0 >= 0 && data0 < datalen_limit);
381 }
382
383 public:
384 // Support routines for compilers.
385
386 // This routine takes an infant relocInfo (unprefixed) and
387 // edits in its prefix, if any. It also updates dest.locs_end.
388 void initialize(CodeSection* dest, Relocation* reloc);
389
390 // This routine updates a prefix and returns the limit pointer.
391 // It tries to compress the prefix from 32 to 16 bits, and if
392 // successful returns a reduced "prefix_limit" pointer.
393 relocInfo* finish_prefix(short* prefix_limit);
394
395 // bit-packers for the data array:
396
397 // As it happens, the bytes within the shorts are ordered natively,
398 // but the shorts within the word are ordered big-endian.
399 // This is an arbitrary choice, made this way mainly to ease debugging.
400 static int data0_from_int(jint x) { return x >> value_width; }
401 static int data1_from_int(jint x) { return (short)x; }
402 static jint jint_from_data(short* data) {
403 return (data[0] << value_width) + (unsigned short)data[1];
404 }
405
406 static jint short_data_at(int n, short* data, int datalen) {
407 return datalen > n ? data[n] : 0;
408 }
409
410 static jint jint_data_at(int n, short* data, int datalen) {
411 return datalen > n+1 ? jint_from_data(&data[n]) : short_data_at(n, data, datalen);
412 }
413
414 // Update methods for relocation information
415 // (since code is dynamically patched, we also need to dynamically update the relocation info)
416 // Both methods takes old_type, so it is able to performe sanity checks on the information removed.
417 static void change_reloc_info_for_address(RelocIterator *itr, address pc, relocType old_type, relocType new_type);
418 static void remove_reloc_info_for_address(RelocIterator *itr, address pc, relocType old_type);
419
420 // Machine dependent stuff
421 #include "incls/_relocInfo_pd.hpp.incl"
422
423 protected:
424 // Derived constant, based on format_width which is PD:
425 enum {
426 offset_width = nontype_width - format_width,
427 offset_mask = (1<<offset_width) - 1,
428 format_mask = (1<<format_width) - 1
429 };
430 public:
431 enum {
432 // Conservatively large estimate of maximum length (in shorts)
433 // of any relocation record (probably breakpoints are largest).
434 // Extended format is length prefix, data words, and tag/offset suffix.
435 length_limit = 1 + 1 + (3*BytesPerWord/BytesPerShort) + 1,
436 have_format = format_width > 0
437 };
438 };
439
440 #define FORWARD_DECLARE_EACH_CLASS(name) \
441 class name##_Relocation;
442 APPLY_TO_RELOCATIONS(FORWARD_DECLARE_EACH_CLASS)
443 #undef FORWARD_DECLARE_EACH_CLASS
444
445
446
447 inline relocInfo filler_relocInfo() {
448 return relocInfo(relocInfo::none, relocInfo::offset_limit() - relocInfo::offset_unit);
449 }
450
451 inline relocInfo prefix_relocInfo(int datalen) {
452 assert(relocInfo::fits_into_immediate(datalen), "datalen in limits");
453 return relocInfo(relocInfo::data_prefix_tag, relocInfo::RAW_BITS, relocInfo::datalen_tag | datalen);
454 }
455
456
457 // Holder for flyweight relocation objects.
458 // Although the flyweight subclasses are of varying sizes,
459 // the holder is "one size fits all".
460 class RelocationHolder VALUE_OBJ_CLASS_SPEC {
461 friend class Relocation;
462 friend class CodeSection;
463
464 private:
465 // this preallocated memory must accommodate all subclasses of Relocation
466 // (this number is assertion-checked in Relocation::operator new)
467 enum { _relocbuf_size = 5 };
468 void* _relocbuf[ _relocbuf_size ];
469
470 public:
471 Relocation* reloc() const { return (Relocation*) &_relocbuf[0]; }
472 inline relocInfo::relocType type() const;
473
474 // Add a constant offset to a relocation. Helper for class Address.
475 RelocationHolder plus(int offset) const;
476
477 inline RelocationHolder(); // initializes type to none
478
479 inline RelocationHolder(Relocation* r); // make a copy
480
481 static const RelocationHolder none;
482 };
483
484 // A RelocIterator iterates through the relocation information of a CodeBlob.
485 // It is a variable BoundRelocation which is able to take on successive
486 // values as it is advanced through a code stream.
487 // Usage:
488 // RelocIterator iter(nm);
489 // while (iter.next()) {
490 // iter.reloc()->some_operation();
491 // }
492 // or:
493 // RelocIterator iter(nm);
494 // while (iter.next()) {
495 // switch (iter.type()) {
496 // case relocInfo::oop_type :
497 // case relocInfo::ic_type :
498 // case relocInfo::prim_type :
499 // case relocInfo::uncommon_type :
500 // case relocInfo::runtime_call_type :
501 // case relocInfo::internal_word_type:
502 // case relocInfo::external_word_type:
503 // ...
504 // }
505 // }
506
507 class RelocIterator : public StackObj {
508 enum { SECT_CONSTS = 2,
509 SECT_LIMIT = 3 }; // must be equal to CodeBuffer::SECT_LIMIT
510 friend class Relocation;
511 friend class relocInfo; // for change_reloc_info_for_address only
512 typedef relocInfo::relocType relocType;
513
514 private:
515 address _limit; // stop producing relocations after this _addr
516 relocInfo* _current; // the current relocation information
517 relocInfo* _end; // end marker; we're done iterating when _current == _end
518 CodeBlob* _code; // compiled method containing _addr
519 address _addr; // instruction to which the relocation applies
520 short _databuf; // spare buffer for compressed data
521 short* _data; // pointer to the relocation's data
522 short _datalen; // number of halfwords in _data
523 char _format; // position within the instruction
524
525 // Base addresses needed to compute targets of section_word_type relocs.
526 address _section_start[SECT_LIMIT];
527
528 void set_has_current(bool b) {
529 _datalen = !b ? -1 : 0;
530 debug_only(_data = NULL);
531 }
532 void set_current(relocInfo& ri) {
533 _current = &ri;
534 set_has_current(true);
535 }
536
537 RelocationHolder _rh; // where the current relocation is allocated
538
539 relocInfo* current() const { assert(has_current(), "must have current");
540 return _current; }
541
542 void set_limits(address begin, address limit);
543
544 void advance_over_prefix(); // helper method
545
546 void initialize_misc() {
547 set_has_current(false);
548 for (int i = 0; i < SECT_LIMIT; i++) {
549 _section_start[i] = NULL; // these will be lazily computed, if needed
550 }
551 }
552
553 address compute_section_start(int n) const; // out-of-line helper
554
555 void initialize(CodeBlob* nm, address begin, address limit);
556
557 friend class PatchingRelocIterator;
558 // make an uninitialized one, for PatchingRelocIterator:
559 RelocIterator() { initialize_misc(); }
560
561 public:
562 // constructor
563 RelocIterator(CodeBlob* cb, address begin = NULL, address limit = NULL);
564 RelocIterator(CodeSection* cb, address begin = NULL, address limit = NULL);
565
566 // get next reloc info, return !eos
567 bool next() {
568 _current++;
569 assert(_current <= _end, "must not overrun relocInfo");
570 if (_current == _end) {
571 set_has_current(false);
572 return false;
573 }
574 set_has_current(true);
575
576 if (_current->is_prefix()) {
577 advance_over_prefix();
578 assert(!current()->is_prefix(), "only one prefix at a time");
579 }
580
581 _addr += _current->addr_offset();
582
583 if (_limit != NULL && _addr >= _limit) {
584 set_has_current(false);
585 return false;
586 }
587
588 if (relocInfo::have_format) _format = current()->format();
589 return true;
590 }
591
592 // accessors
593 address limit() const { return _limit; }
594 void set_limit(address x);
595 relocType type() const { return current()->type(); }
596 int format() const { return (relocInfo::have_format) ? current()->format() : 0; }
597 address addr() const { return _addr; }
598 CodeBlob* code() const { return _code; }
599 short* data() const { return _data; }
600 int datalen() const { return _datalen; }
601 bool has_current() const { return _datalen >= 0; }
602
603 void set_addr(address addr) { _addr = addr; }
604 bool addr_in_const() const { return addr() >= section_start(SECT_CONSTS); }
605
606 address section_start(int n) const {
607 address res = _section_start[n];
608 return (res != NULL) ? res : compute_section_start(n);
609 }
610
611 // The address points to the affected displacement part of the instruction.
612 // For RISC, this is just the whole instruction.
613 // For Intel, this is an unaligned 32-bit word.
614
615 // type-specific relocation accessors: oop_Relocation* oop_reloc(), etc.
616 #define EACH_TYPE(name) \
617 inline name##_Relocation* name##_reloc();
618 APPLY_TO_RELOCATIONS(EACH_TYPE)
619 #undef EACH_TYPE
620 // generic relocation accessor; switches on type to call the above
621 Relocation* reloc();
622
623 // CodeBlob's have relocation indexes for faster random access:
624 static int locs_and_index_size(int code_size, int locs_size);
625 // Store an index into [dest_start+dest_count..dest_end).
626 // At dest_start[0..dest_count] is the actual relocation information.
627 // Everything else up to dest_end is free space for the index.
628 static void create_index(relocInfo* dest_begin, int dest_count, relocInfo* dest_end);
629
630 #ifndef PRODUCT
631 public:
632 void print();
633 void print_current();
634 #endif
635 };
636
637
638 // A Relocation is a flyweight object allocated within a RelocationHolder.
639 // It represents the relocation data of relocation record.
640 // So, the RelocIterator unpacks relocInfos into Relocations.
641
642 class Relocation VALUE_OBJ_CLASS_SPEC {
643 friend class RelocationHolder;
644 friend class RelocIterator;
645
646 private:
647 static void guarantee_size();
648
649 // When a relocation has been created by a RelocIterator,
650 // this field is non-null. It allows the relocation to know
651 // its context, such as the address to which it applies.
652 RelocIterator* _binding;
653
654 protected:
655 RelocIterator* binding() const {
656 assert(_binding != NULL, "must be bound");
657 return _binding;
658 }
659 void set_binding(RelocIterator* b) {
660 assert(_binding == NULL, "must be unbound");
661 _binding = b;
662 assert(_binding != NULL, "must now be bound");
663 }
664
665 Relocation() {
666 _binding = NULL;
667 }
668
669 static RelocationHolder newHolder() {
670 return RelocationHolder();
671 }
672
673 public:
674 void* operator new(size_t size, const RelocationHolder& holder) {
675 if (size > sizeof(holder._relocbuf)) guarantee_size();
676 assert((void* const *)holder.reloc() == &holder._relocbuf[0], "ptrs must agree");
677 return holder.reloc();
678 }
679
680 // make a generic relocation for a given type (if possible)
681 static RelocationHolder spec_simple(relocInfo::relocType rtype);
682
683 // here is the type-specific hook which writes relocation data:
684 virtual void pack_data_to(CodeSection* dest) { }
685
686 // here is the type-specific hook which reads (unpacks) relocation data:
687 virtual void unpack_data() {
688 assert(datalen()==0 || type()==relocInfo::none, "no data here");
689 }
690
691 protected:
692 // Helper functions for pack_data_to() and unpack_data().
693
694 // Most of the compression logic is confined here.
695 // (The "immediate data" mechanism of relocInfo works independently
696 // of this stuff, and acts to further compress most 1-word data prefixes.)
697
698 // A variable-width int is encoded as a short if it will fit in 16 bits.
699 // The decoder looks at datalen to decide whether to unpack short or jint.
700 // Most relocation records are quite simple, containing at most two ints.
701
702 static bool is_short(jint x) { return x == (short)x; }
703 static short* add_short(short* p, int x) { *p++ = x; return p; }
704 static short* add_jint (short* p, jint x) {
705 *p++ = relocInfo::data0_from_int(x); *p++ = relocInfo::data1_from_int(x);
706 return p;
707 }
708 static short* add_var_int(short* p, jint x) { // add a variable-width int
709 if (is_short(x)) p = add_short(p, x);
710 else p = add_jint (p, x);
711 return p;
712 }
713
714 static short* pack_1_int_to(short* p, jint x0) {
715 // Format is one of: [] [x] [Xx]
716 if (x0 != 0) p = add_var_int(p, x0);
717 return p;
718 }
719 int unpack_1_int() {
720 assert(datalen() <= 2, "too much data");
721 return relocInfo::jint_data_at(0, data(), datalen());
722 }
723
724 // With two ints, the short form is used only if both ints are short.
725 short* pack_2_ints_to(short* p, jint x0, jint x1) {
726 // Format is one of: [] [x y?] [Xx Y?y]
727 if (x0 == 0 && x1 == 0) {
728 // no halfwords needed to store zeroes
729 } else if (is_short(x0) && is_short(x1)) {
730 // 1-2 halfwords needed to store shorts
731 p = add_short(p, x0); if (x1!=0) p = add_short(p, x1);
732 } else {
733 // 3-4 halfwords needed to store jints
734 p = add_jint(p, x0); p = add_var_int(p, x1);
735 }
736 return p;
737 }
738 void unpack_2_ints(jint& x0, jint& x1) {
739 int dlen = datalen();
740 short* dp = data();
741 if (dlen <= 2) {
742 x0 = relocInfo::short_data_at(0, dp, dlen);
743 x1 = relocInfo::short_data_at(1, dp, dlen);
744 } else {
745 assert(dlen <= 4, "too much data");
746 x0 = relocInfo::jint_data_at(0, dp, dlen);
747 x1 = relocInfo::jint_data_at(2, dp, dlen);
748 }
749 }
750
751 protected:
752 // platform-dependent utilities for decoding and patching instructions
753 void pd_set_data_value (address x, intptr_t off); // a set or mem-ref
754 address pd_call_destination (address orig_addr = NULL);
755 void pd_set_call_destination (address x);
756 void pd_swap_in_breakpoint (address x, short* instrs, int instrlen);
757 void pd_swap_out_breakpoint (address x, short* instrs, int instrlen);
758 static int pd_breakpoint_size ();
759
760 // this extracts the address of an address in the code stream instead of the reloc data
761 address* pd_address_in_code ();
762
763 // this extracts an address from the code stream instead of the reloc data
764 address pd_get_address_from_code ();
765
766 // these convert from byte offsets, to scaled offsets, to addresses
767 static jint scaled_offset(address x, address base) {
768 int byte_offset = x - base;
769 int offset = -byte_offset / relocInfo::addr_unit();
770 assert(address_from_scaled_offset(offset, base) == x, "just checkin'");
771 return offset;
772 }
773 static jint scaled_offset_null_special(address x, address base) {
774 // Some relocations treat offset=0 as meaning NULL.
775 // Handle this extra convention carefully.
776 if (x == NULL) return 0;
777 assert(x != base, "offset must not be zero");
778 return scaled_offset(x, base);
779 }
780 static address address_from_scaled_offset(jint offset, address base) {
781 int byte_offset = -( offset * relocInfo::addr_unit() );
782 return base + byte_offset;
783 }
784
785 // these convert between indexes and addresses in the runtime system
786 static int32_t runtime_address_to_index(address runtime_address);
787 static address index_to_runtime_address(int32_t index);
788
789 // helpers for mapping between old and new addresses after a move or resize
790 address old_addr_for(address newa, const CodeBuffer* src, CodeBuffer* dest);
791 address new_addr_for(address olda, const CodeBuffer* src, CodeBuffer* dest);
792 void normalize_address(address& addr, const CodeSection* dest, bool allow_other_sections = false);
793
794 public:
795 // accessors which only make sense for a bound Relocation
796 address addr() const { return binding()->addr(); }
797 CodeBlob* code() const { return binding()->code(); }
798 bool addr_in_const() const { return binding()->addr_in_const(); }
799 protected:
800 short* data() const { return binding()->data(); }
801 int datalen() const { return binding()->datalen(); }
802 int format() const { return binding()->format(); }
803
804 public:
805 virtual relocInfo::relocType type() { return relocInfo::none; }
806
807 // is it a call instruction?
808 virtual bool is_call() { return false; }
809
810 // is it a data movement instruction?
811 virtual bool is_data() { return false; }
812
813 // some relocations can compute their own values
814 virtual address value();
815
816 // all relocations are able to reassert their values
817 virtual void set_value(address x);
818
819 virtual void clear_inline_cache() { }
820
821 // This method assumes that all virtual/static (inline) caches are cleared (since for static_call_type and
822 // ic_call_type is not always posisition dependent (depending on the state of the cache)). However, this is
823 // probably a reasonable assumption, since empty caches simplifies code reloacation.
824 virtual void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest) { }
825
826 void print();
827 };
828
829
830 // certain inlines must be deferred until class Relocation is defined:
831
832 inline RelocationHolder::RelocationHolder() {
833 // initialize the vtbl, just to keep things type-safe
834 new(*this) Relocation();
835 }
836
837
838 inline RelocationHolder::RelocationHolder(Relocation* r) {
839 // wordwise copy from r (ok if it copies garbage after r)
840 for (int i = 0; i < _relocbuf_size; i++) {
841 _relocbuf[i] = ((void**)r)[i];
842 }
843 }
844
845
846 relocInfo::relocType RelocationHolder::type() const {
847 return reloc()->type();
848 }
849
850 // A DataRelocation always points at a memory or load-constant instruction..
851 // It is absolute on most machines, and the constant is split on RISCs.
852 // The specific subtypes are oop, external_word, and internal_word.
853 // By convention, the "value" does not include a separately reckoned "offset".
854 class DataRelocation : public Relocation {
855 public:
856 bool is_data() { return true; }
857
858 // both target and offset must be computed somehow from relocation data
859 virtual int offset() { return 0; }
860 address value() = 0;
861 void set_value(address x) { set_value(x, offset()); }
862 void set_value(address x, intptr_t o) {
863 if (addr_in_const())
864 *(address*)addr() = x;
865 else
866 pd_set_data_value(x, o);
867 }
868
869 // The "o" (displacement) argument is relevant only to split relocations
870 // on RISC machines. In some CPUs (SPARC), the set-hi and set-lo ins'ns
871 // can encode more than 32 bits between them. This allows compilers to
872 // share set-hi instructions between addresses that differ by a small
873 // offset (e.g., different static variables in the same class).
874 // On such machines, the "x" argument to set_value on all set-lo
875 // instructions must be the same as the "x" argument for the
876 // corresponding set-hi instructions. The "o" arguments for the
877 // set-hi instructions are ignored, and must not affect the high-half
878 // immediate constant. The "o" arguments for the set-lo instructions are
879 // added into the low-half immediate constant, and must not overflow it.
880 };
881
882 // A CallRelocation always points at a call instruction.
883 // It is PC-relative on most machines.
884 class CallRelocation : public Relocation {
885 public:
886 bool is_call() { return true; }
887
888 address destination() { return pd_call_destination(); }
889 void set_destination(address x); // pd_set_call_destination
890
891 void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest);
892 address value() { return destination(); }
893 void set_value(address x) { set_destination(x); }
894 };
895
896 class oop_Relocation : public DataRelocation {
897 relocInfo::relocType type() { return relocInfo::oop_type; }
898
899 public:
900 // encode in one of these formats: [] [n] [n l] [Nn l] [Nn Ll]
901 // an oop in the CodeBlob's oop pool
902 static RelocationHolder spec(int oop_index, int offset = 0) {
903 assert(oop_index > 0, "must be a pool-resident oop");
904 RelocationHolder rh = newHolder();
905 new(rh) oop_Relocation(oop_index, offset);
906 return rh;
907 }
908 // an oop in the instruction stream
909 static RelocationHolder spec_for_immediate() {
910 const int oop_index = 0;
911 const int offset = 0; // if you want an offset, use the oop pool
912 RelocationHolder rh = newHolder();
913 new(rh) oop_Relocation(oop_index, offset);
914 return rh;
915 }
916
917 private:
918 jint _oop_index; // if > 0, index into CodeBlob::oop_at
919 jint _offset; // byte offset to apply to the oop itself
920
921 oop_Relocation(int oop_index, int offset) {
922 _oop_index = oop_index; _offset = offset;
923 }
924
925 friend class RelocIterator;
926 oop_Relocation() { }
927
928 public:
929 int oop_index() { return _oop_index; }
930 int offset() { return _offset; }
931
932 // data is packed in "2_ints" format: [i o] or [Ii Oo]
933 void pack_data_to(CodeSection* dest);
934 void unpack_data();
935
936 void fix_oop_relocation(); // reasserts oop value
937
938 address value() { return (address) *oop_addr(); }
939
940 bool oop_is_immediate() { return oop_index() == 0; }
941
942 oop* oop_addr(); // addr or &pool[jint_data]
943 oop oop_value(); // *oop_addr
944 // Note: oop_value transparently converts Universe::non_oop_word to NULL.
945 };
946
947 class virtual_call_Relocation : public CallRelocation {
948 relocInfo::relocType type() { return relocInfo::virtual_call_type; }
949
950 public:
951 // "first_oop" points to the first associated set-oop.
952 // The oop_limit helps find the last associated set-oop.
953 // (See comments at the top of this file.)
954 static RelocationHolder spec(address first_oop, address oop_limit = NULL) {
955 RelocationHolder rh = newHolder();
956 new(rh) virtual_call_Relocation(first_oop, oop_limit);
957 return rh;
958 }
959
960 virtual_call_Relocation(address first_oop, address oop_limit) {
961 _first_oop = first_oop; _oop_limit = oop_limit;
962 assert(first_oop != NULL, "first oop address must be specified");
963 }
964
965 private:
966 address _first_oop; // location of first set-oop instruction
967 address _oop_limit; // search limit for set-oop instructions
968
969 friend class RelocIterator;
970 virtual_call_Relocation() { }
971
972
973 public:
974 address first_oop();
975 address oop_limit();
976
977 // data is packed as scaled offsets in "2_ints" format: [f l] or [Ff Ll]
978 // oop_limit is set to 0 if the limit falls somewhere within the call.
979 // When unpacking, a zero oop_limit is taken to refer to the end of the call.
980 // (This has the effect of bringing in the call's delay slot on SPARC.)
981 void pack_data_to(CodeSection* dest);
982 void unpack_data();
983
984 void clear_inline_cache();
985
986 // Figure out where an ic_call is hiding, given a set-oop or call.
987 // Either ic_call or first_oop must be non-null; the other is deduced.
988 // Code if non-NULL must be the CodeBlob, else it is deduced.
989 // The address of the patchable oop is also deduced.
990 // The returned iterator will enumerate over the oops and the ic_call,
991 // as well as any other relocations that happen to be in that span of code.
992 // Recognize relevant set_oops with: oop_reloc()->oop_addr() == oop_addr.
993 static RelocIterator parse_ic(CodeBlob* &code, address &ic_call, address &first_oop, oop* &oop_addr, bool *is_optimized);
994 };
995
996
997 class opt_virtual_call_Relocation : public CallRelocation {
998 relocInfo::relocType type() { return relocInfo::opt_virtual_call_type; }
999
1000 public:
1001 static RelocationHolder spec() {
1002 RelocationHolder rh = newHolder();
1003 new(rh) opt_virtual_call_Relocation();
1004 return rh;
1005 }
1006
1007 private:
1008 friend class RelocIterator;
1009 opt_virtual_call_Relocation() { }
1010
1011 public:
1012 void clear_inline_cache();
1013
1014 // find the matching static_stub
1015 address static_stub();
1016 };
1017
1018
1019 class static_call_Relocation : public CallRelocation {
1020 relocInfo::relocType type() { return relocInfo::static_call_type; }
1021
1022 public:
1023 static RelocationHolder spec() {
1024 RelocationHolder rh = newHolder();
1025 new(rh) static_call_Relocation();
1026 return rh;
1027 }
1028
1029 private:
1030 friend class RelocIterator;
1031 static_call_Relocation() { }
1032
1033 public:
1034 void clear_inline_cache();
1035
1036 // find the matching static_stub
1037 address static_stub();
1038 };
1039
1040 class static_stub_Relocation : public Relocation {
1041 relocInfo::relocType type() { return relocInfo::static_stub_type; }
1042
1043 public:
1044 static RelocationHolder spec(address static_call) {
1045 RelocationHolder rh = newHolder();
1046 new(rh) static_stub_Relocation(static_call);
1047 return rh;
1048 }
1049
1050 private:
1051 address _static_call; // location of corresponding static_call
1052
1053 static_stub_Relocation(address static_call) {
1054 _static_call = static_call;
1055 }
1056
1057 friend class RelocIterator;
1058 static_stub_Relocation() { }
1059
1060 public:
1061 void clear_inline_cache();
1062
1063 address static_call() { return _static_call; }
1064
1065 // data is packed as a scaled offset in "1_int" format: [c] or [Cc]
1066 void pack_data_to(CodeSection* dest);
1067 void unpack_data();
1068 };
1069
1070 class runtime_call_Relocation : public CallRelocation {
1071 relocInfo::relocType type() { return relocInfo::runtime_call_type; }
1072
1073 public:
1074 static RelocationHolder spec() {
1075 RelocationHolder rh = newHolder();
1076 new(rh) runtime_call_Relocation();
1077 return rh;
1078 }
1079
1080 private:
1081 friend class RelocIterator;
1082 runtime_call_Relocation() { }
1083
1084 public:
1085 };
1086
1087 class external_word_Relocation : public DataRelocation {
1088 relocInfo::relocType type() { return relocInfo::external_word_type; }
1089
1090 public:
1091 static RelocationHolder spec(address target) {
1092 assert(target != NULL, "must not be null");
1093 RelocationHolder rh = newHolder();
1094 new(rh) external_word_Relocation(target);
1095 return rh;
1096 }
1097
1098 // Use this one where all 32/64 bits of the target live in the code stream.
1099 // The target must be an intptr_t, and must be absolute (not relative).
1100 static RelocationHolder spec_for_immediate() {
1101 RelocationHolder rh = newHolder();
1102 new(rh) external_word_Relocation(NULL);
1103 return rh;
1104 }
1105
1106 private:
1107 address _target; // address in runtime
1108
1109 external_word_Relocation(address target) {
1110 _target = target;
1111 }
1112
1113 friend class RelocIterator;
1114 external_word_Relocation() { }
1115
1116 public:
1117 // data is packed as a well-known address in "1_int" format: [a] or [Aa]
1118 // The function runtime_address_to_index is used to turn full addresses
1119 // to short indexes, if they are pre-registered by the stub mechanism.
1120 // If the "a" value is 0 (i.e., _target is NULL), the address is stored
1121 // in the code stream. See external_word_Relocation::target().
1122 void pack_data_to(CodeSection* dest);
1123 void unpack_data();
1124
1125 void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest);
1126 address target(); // if _target==NULL, fetch addr from code stream
1127 address value() { return target(); }
1128 };
1129
1130 class internal_word_Relocation : public DataRelocation {
1131 relocInfo::relocType type() { return relocInfo::internal_word_type; }
1132
1133 public:
1134 static RelocationHolder spec(address target) {
1135 assert(target != NULL, "must not be null");
1136 RelocationHolder rh = newHolder();
1137 new(rh) internal_word_Relocation(target);
1138 return rh;
1139 }
1140
1141 // use this one where all the bits of the target can fit in the code stream:
1142 static RelocationHolder spec_for_immediate() {
1143 RelocationHolder rh = newHolder();
1144 new(rh) internal_word_Relocation(NULL);
1145 return rh;
1146 }
1147
1148 internal_word_Relocation(address target) {
1149 _target = target;
1150 _section = -1; // self-relative
1151 }
1152
1153 protected:
1154 address _target; // address in CodeBlob
1155 int _section; // section providing base address, if any
1156
1157 friend class RelocIterator;
1158 internal_word_Relocation() { }
1159
1160 // bit-width of LSB field in packed offset, if section >= 0
1161 enum { section_width = 2 }; // must equal CodeBuffer::sect_bits
1162
1163 public:
1164 // data is packed as a scaled offset in "1_int" format: [o] or [Oo]
1165 // If the "o" value is 0 (i.e., _target is NULL), the offset is stored
1166 // in the code stream. See internal_word_Relocation::target().
1167 // If _section is not -1, it is appended to the low bits of the offset.
1168 void pack_data_to(CodeSection* dest);
1169 void unpack_data();
1170
1171 void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest);
1172 address target(); // if _target==NULL, fetch addr from code stream
1173 int section() { return _section; }
1174 address value() { return target(); }
1175 };
1176
1177 class section_word_Relocation : public internal_word_Relocation {
1178 relocInfo::relocType type() { return relocInfo::section_word_type; }
1179
1180 public:
1181 static RelocationHolder spec(address target, int section) {
1182 RelocationHolder rh = newHolder();
1183 new(rh) section_word_Relocation(target, section);
1184 return rh;
1185 }
1186
1187 section_word_Relocation(address target, int section) {
1188 assert(target != NULL, "must not be null");
1189 assert(section >= 0, "must be a valid section");
1190 _target = target;
1191 _section = section;
1192 }
1193
1194 //void pack_data_to -- inherited
1195 void unpack_data();
1196
1197 private:
1198 friend class RelocIterator;
1199 section_word_Relocation() { }
1200 };
1201
1202
1203 class poll_Relocation : public Relocation {
1204 bool is_data() { return true; }
1205 relocInfo::relocType type() { return relocInfo::poll_type; }
1206 };
1207
1208 class poll_return_Relocation : public Relocation {
1209 bool is_data() { return true; }
1210 relocInfo::relocType type() { return relocInfo::poll_return_type; }
1211 };
1212
1213
1214 class breakpoint_Relocation : public Relocation {
1215 relocInfo::relocType type() { return relocInfo::breakpoint_type; }
1216
1217 enum {
1218 // attributes which affect the interpretation of the data:
1219 removable_attr = 0x0010, // buffer [i...] allows for undoing the trap
1220 internal_attr = 0x0020, // the target is an internal addr (local stub)
1221 settable_attr = 0x0040, // the target is settable
1222
1223 // states which can change over time:
1224 enabled_state = 0x0100, // breakpoint must be active in running code
1225 active_state = 0x0200, // breakpoint instruction actually in code
1226
1227 kind_mask = 0x000F, // mask for extracting kind
1228 high_bit = 0x4000 // extra bit which is always set
1229 };
1230
1231 public:
1232 enum {
1233 // kinds:
1234 initialization = 1,
1235 safepoint = 2
1236 };
1237
1238 // If target is NULL, 32 bits are reserved for a later set_target().
1239 static RelocationHolder spec(int kind, address target = NULL, bool internal_target = false) {
1240 RelocationHolder rh = newHolder();
1241 new(rh) breakpoint_Relocation(kind, target, internal_target);
1242 return rh;
1243 }
1244
1245 private:
1246 // We require every bits value to NOT to fit into relocInfo::datalen_width,
1247 // because we are going to actually store state in the reloc, and so
1248 // cannot allow it to be compressed (and hence copied by the iterator).
1249
1250 short _bits; // bit-encoded kind, attrs, & state
1251 address _target;
1252
1253 breakpoint_Relocation(int kind, address target, bool internal_target);
1254
1255 friend class RelocIterator;
1256 breakpoint_Relocation() { }
1257
1258 short bits() const { return _bits; }
1259 short& live_bits() const { return data()[0]; }
1260 short* instrs() const { return data() + datalen() - instrlen(); }
1261 int instrlen() const { return removable() ? pd_breakpoint_size() : 0; }
1262
1263 void set_bits(short x) {
1264 assert(live_bits() == _bits, "must be the only mutator of reloc info");
1265 live_bits() = _bits = x;
1266 }
1267
1268 public:
1269 address target() const;
1270 void set_target(address x);
1271
1272 int kind() const { return bits() & kind_mask; }
1273 bool enabled() const { return (bits() & enabled_state) != 0; }
1274 bool active() const { return (bits() & active_state) != 0; }
1275 bool internal() const { return (bits() & internal_attr) != 0; }
1276 bool removable() const { return (bits() & removable_attr) != 0; }
1277 bool settable() const { return (bits() & settable_attr) != 0; }
1278
1279 void set_enabled(bool b); // to activate, you must also say set_active
1280 void set_active(bool b); // actually inserts bpt (must be enabled 1st)
1281
1282 // data is packed as 16 bits, followed by the target (1 or 2 words), followed
1283 // if necessary by empty storage for saving away original instruction bytes.
1284 void pack_data_to(CodeSection* dest);
1285 void unpack_data();
1286
1287 // during certain operations, breakpoints must be out of the way:
1288 void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest) {
1289 assert(!active(), "cannot perform relocation on enabled breakpoints");
1290 }
1291 };
1292
1293
1294 // We know all the xxx_Relocation classes, so now we can define these:
1295 #define EACH_CASE(name) \
1296 inline name##_Relocation* RelocIterator::name##_reloc() { \
1297 assert(type() == relocInfo::name##_type, "type must agree"); \
1298 /* The purpose of the placed "new" is to re-use the same */ \
1299 /* stack storage for each new iteration. */ \
1300 name##_Relocation* r = new(_rh) name##_Relocation(); \
1301 r->set_binding(this); \
1302 r->name##_Relocation::unpack_data(); \
1303 return r; \
1304 }
1305 APPLY_TO_RELOCATIONS(EACH_CASE);
1306 #undef EACH_CASE
1307
1308 inline RelocIterator::RelocIterator(CodeBlob* cb, address begin, address limit) {
1309 initialize(cb, begin, limit);
1310 }
1311
1312 // if you are going to patch code, you should use this subclass of
1313 // RelocIterator
1314 class PatchingRelocIterator : public RelocIterator {
1315 private:
1316 RelocIterator _init_state;
1317
1318 void prepass(); // deactivates all breakpoints
1319 void postpass(); // reactivates all enabled breakpoints
1320
1321 // do not copy these puppies; it would have unpredictable side effects
1322 // these are private and have no bodies defined because they should not be called
1323 PatchingRelocIterator(const RelocIterator&);
1324 void operator=(const RelocIterator&);
1325
1326 public:
1327 PatchingRelocIterator(CodeBlob* cb, address begin =NULL, address limit =NULL)
1328 : RelocIterator(cb, begin, limit) { prepass(); }
1329
1330 ~PatchingRelocIterator() { postpass(); }
1331 };
1332