1 /*
2 * Copyright 1997-2008 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 // Types in this file:
26 // relocInfo
27 // One element of an array of halfwords encoding compressed relocations.
28 // Also, the source of relocation types (relocInfo::oop_type, ...).
29 // Relocation
30 // A flyweight object representing a single relocation.
31 // It is fully unpacked from the compressed relocation array.
32 // oop_Relocation, ... (subclasses of Relocation)
33 // The location of some type-specific operations (oop_addr, ...).
34 // Also, the source of relocation specs (oop_Relocation::spec, ...).
35 // RelocationHolder
36 // A ValueObj type which acts as a union holding a Relocation object.
37 // Represents a relocation spec passed into a CodeBuffer during assembly.
38 // RelocIterator
39 // A StackObj which iterates over the relocations associated with
40 // a range of code addresses. Can be used to operate a copy of code.
41 // PatchingRelocIterator
42 // Specialized subtype of RelocIterator which removes breakpoints
43 // temporarily during iteration, then restores them.
44 // BoundRelocation
45 // An _internal_ type shared by packers and unpackers of relocations.
46 // It pastes together a RelocationHolder with some pointers into
47 // code and relocInfo streams.
48
49
50 // Notes on relocType:
51 //
52 // These hold enough information to read or write a value embedded in
53 // the instructions of an CodeBlob. They're used to update:
54 //
55 // 1) embedded oops (isOop() == true)
56 // 2) inline caches (isIC() == true)
57 // 3) runtime calls (isRuntimeCall() == true)
58 // 4) internal word ref (isInternalWord() == true)
59 // 5) external word ref (isExternalWord() == true)
60 //
61 // when objects move (GC) or if code moves (compacting the code heap).
62 // They are also used to patch the code (if a call site must change)
63 //
64 // A relocInfo is represented in 16 bits:
65 // 4 bits indicating the relocation type
66 // 12 bits indicating the offset from the previous relocInfo address
67 //
68 // The offsets accumulate along the relocInfo stream to encode the
69 // address within the CodeBlob, which is named RelocIterator::addr().
70 // The address of a particular relocInfo always points to the first
71 // byte of the relevant instruction (and not to any of its subfields
72 // or embedded immediate constants).
73 //
74 // The offset value is scaled appropriately for the target machine.
75 // (See relocInfo_<arch>.hpp for the offset scaling.)
76 //
77 // On some machines, there may also be a "format" field which may provide
78 // additional information about the format of the instruction stream
79 // at the corresponding code address. The format value is usually zero.
80 // Any machine (such as Intel) whose instructions can sometimes contain
81 // more than one relocatable constant needs format codes to distinguish
82 // which operand goes with a given relocation.
83 //
84 // If the target machine needs N format bits, the offset has 12-N bits,
85 // the format is encoded between the offset and the type, and the
86 // relocInfo_<arch>.hpp file has manifest constants for the format codes.
87 //
88 // If the type is "data_prefix_tag" then the offset bits are further encoded,
89 // and in fact represent not a code-stream offset but some inline data.
90 // The data takes the form of a counted sequence of halfwords, which
91 // precedes the actual relocation record. (Clients never see it directly.)
92 // The interpetation of this extra data depends on the relocation type.
93 //
94 // On machines that have 32-bit immediate fields, there is usually
95 // little need for relocation "prefix" data, because the instruction stream
96 // is a perfectly reasonable place to store the value. On machines in
97 // which 32-bit values must be "split" across instructions, the relocation
98 // data is the "true" specification of the value, which is then applied
99 // to some field of the instruction (22 or 13 bits, on SPARC).
100 //
101 // Whenever the location of the CodeBlob changes, any PC-relative
102 // relocations, and any internal_word_type relocations, must be reapplied.
103 // After the GC runs, oop_type relocations must be reapplied.
104 //
105 //
106 // Here are meanings of the types:
107 //
108 // relocInfo::none -- a filler record
109 // Value: none
110 // Instruction: The corresponding code address is ignored
111 // Data: Any data prefix and format code are ignored
112 // (This means that any relocInfo can be disabled by setting
113 // its type to none. See relocInfo::remove.)
114 //
115 // relocInfo::oop_type -- a reference to an oop
116 // Value: an oop, or else the address (handle) of an oop
117 // Instruction types: memory (load), set (load address)
118 // Data: [] an oop stored in 4 bytes of instruction
119 // [n] n is the index of an oop in the CodeBlob's oop pool
120 // [[N]n l] and l is a byte offset to be applied to the oop
121 // [Nn Ll] both index and offset may be 32 bits if necessary
122 // Here is a special hack, used only by the old compiler:
123 // [[N]n 00] the value is the __address__ of the nth oop in the pool
124 // (Note that the offset allows optimal references to class variables.)
125 //
126 // relocInfo::internal_word_type -- an address within the same CodeBlob
127 // relocInfo::section_word_type -- same, but can refer to another section
128 // Value: an address in the CodeBlob's code or constants section
129 // Instruction types: memory (load), set (load address)
130 // Data: [] stored in 4 bytes of instruction
131 // [[L]l] a relative offset (see [About Offsets] below)
132 // In the case of section_word_type, the offset is relative to a section
133 // base address, and the section number (e.g., SECT_INSTS) is encoded
134 // into the low two bits of the offset L.
135 //
136 // relocInfo::external_word_type -- a fixed address in the runtime system
137 // Value: an address
138 // Instruction types: memory (load), set (load address)
139 // Data: [] stored in 4 bytes of instruction
140 // [n] the index of a "well-known" stub (usual case on RISC)
141 // [Ll] a 32-bit address
142 //
143 // relocInfo::runtime_call_type -- a fixed subroutine in the runtime system
144 // Value: an address
145 // Instruction types: PC-relative call (or a PC-relative branch)
146 // Data: [] stored in 4 bytes of instruction
147 //
148 // relocInfo::static_call_type -- a static call
149 // Value: an CodeBlob, a stub, or a fixup routine
150 // Instruction types: a call
151 // Data: []
152 // The identity of the callee is extracted from debugging information.
153 // //%note reloc_3
154 //
155 // relocInfo::virtual_call_type -- a virtual call site (which includes an inline
156 // cache)
157 // Value: an CodeBlob, a stub, the interpreter, or a fixup routine
158 // Instruction types: a call, plus some associated set-oop instructions
159 // Data: [] the associated set-oops are adjacent to the call
160 // [n] n is a relative offset to the first set-oop
161 // [[N]n l] and l is a limit within which the set-oops occur
162 // [Nn Ll] both n and l may be 32 bits if necessary
163 // The identity of the callee is extracted from debugging information.
164 //
165 // relocInfo::opt_virtual_call_type -- a virtual call site that is statically bound
166 //
167 // Same info as a static_call_type. We use a special type, so the handling of
168 // virtuals and statics are separated.
169 //
170 //
171 // The offset n points to the first set-oop. (See [About Offsets] below.)
172 // In turn, the set-oop instruction specifies or contains an oop cell devoted
173 // exclusively to the IC call, which can be patched along with the call.
174 //
175 // The locations of any other set-oops are found by searching the relocation
176 // information starting at the first set-oop, and continuing until all
177 // relocations up through l have been inspected. The value l is another
178 // relative offset. (Both n and l are relative to the call's first byte.)
179 //
180 // The limit l of the search is exclusive. However, if it points within
181 // the call (e.g., offset zero), it is adjusted to point after the call and
182 // any associated machine-specific delay slot.
183 //
184 // Since the offsets could be as wide as 32-bits, these conventions
185 // put no restrictions whatever upon code reorganization.
186 //
187 // The compiler is responsible for ensuring that transition from a clean
188 // state to a monomorphic compiled state is MP-safe. This implies that
189 // the system must respond well to intermediate states where a random
190 // subset of the set-oops has been correctly from the clean state
191 // upon entry to the VEP of the compiled method. In the case of a
192 // machine (Intel) with a single set-oop instruction, the 32-bit
193 // immediate field must not straddle a unit of memory coherence.
194 // //%note reloc_3
195 //
196 // relocInfo::breakpoint_type -- a conditional breakpoint in the code
197 // Value: none
198 // Instruction types: any whatsoever
199 // Data: [b [T]t i...]
200 // The b is a bit-packed word representing the breakpoint's attributes.
201 // The t is a target address which the breakpoint calls (when it is enabled).
202 // The i... is a place to store one or two instruction words overwritten
203 // by a trap, so that the breakpoint may be subsequently removed.
204 //
205 // relocInfo::static_stub_type -- an extra stub for each static_call_type
206 // Value: none
207 // Instruction types: a virtual call: { set_oop; jump; }
208 // Data: [[N]n] the offset of the associated static_call reloc
209 // This stub becomes the target of a static call which must be upgraded
210 // to a virtual call (because the callee is interpreted).
211 // See [About Offsets] below.
212 // //%note reloc_2
213 //
214 // For example:
215 //
216 // INSTRUCTIONS RELOC: TYPE PREFIX DATA
217 // ------------ ---- -----------
218 // sethi %hi(myObject), R oop_type [n(myObject)]
219 // ld [R+%lo(myObject)+fldOffset], R2 oop_type [n(myObject) fldOffset]
220 // add R2, 1, R2
221 // st R2, [R+%lo(myObject)+fldOffset] oop_type [n(myObject) fldOffset]
222 //%note reloc_1
223 //
224 // This uses 4 instruction words, 8 relocation halfwords,
225 // and an entry (which is sharable) in the CodeBlob's oop pool,
226 // for a total of 36 bytes.
227 //
228 // Note that the compiler is responsible for ensuring the "fldOffset" when
229 // added to "%lo(myObject)" does not overflow the immediate fields of the
230 // memory instructions.
231 //
232 //
233 // [About Offsets] Relative offsets are supplied to this module as
234 // positive byte offsets, but they may be internally stored scaled
235 // and/or negated, depending on what is most compact for the target
236 // system. Since the object pointed to by the offset typically
237 // precedes the relocation address, it is profitable to store
238 // these negative offsets as positive numbers, but this decision
239 // is internal to the relocation information abstractions.
240 //
241
242 class Relocation;
243 class CodeBuffer;
244 class CodeSection;
245 class RelocIterator;
246
247 class relocInfo VALUE_OBJ_CLASS_SPEC {
248 friend class RelocIterator;
249 public:
250 enum relocType {
251 none = 0, // Used when no relocation should be generated
252 oop_type = 1, // embedded oop
253 virtual_call_type = 2, // a standard inline cache call for a virtual send
254 opt_virtual_call_type = 3, // a virtual call that has been statically bound (i.e., no IC cache)
255 static_call_type = 4, // a static send
256 static_stub_type = 5, // stub-entry for static send (takes care of interpreter case)
257 runtime_call_type = 6, // call to fixed external routine
258 external_word_type = 7, // reference to fixed external address
259 internal_word_type = 8, // reference within the current code blob
260 section_word_type = 9, // internal, but a cross-section reference
261 poll_type = 10, // polling instruction for safepoints
262 poll_return_type = 11, // polling instruction for safepoints at return
263 breakpoint_type = 12, // an initialization barrier or safepoint
264 yet_unused_type = 13, // Still unused
265 yet_unused_type_2 = 14, // Still unused
266 data_prefix_tag = 15, // tag for a prefix (carries data arguments)
267 type_mask = 15 // A mask which selects only the above values
268 };
269
270 protected:
271 unsigned short _value;
272
273 enum RawBitsToken { RAW_BITS };
274 relocInfo(relocType type, RawBitsToken ignore, int bits)
275 : _value((type << nontype_width) + bits) { }
276
277 relocInfo(relocType type, RawBitsToken ignore, int off, int f)
278 : _value((type << nontype_width) + (off / (unsigned)offset_unit) + (f << offset_width)) { }
279
280 public:
281 // constructor
282 relocInfo(relocType type, int offset, int format = 0)
283 #ifndef ASSERT
284 {
285 (*this) = relocInfo(type, RAW_BITS, offset, format);
286 }
287 #else
288 // Put a bunch of assertions out-of-line.
289 ;
290 #endif
291
292 #define APPLY_TO_RELOCATIONS(visitor) \
293 visitor(oop) \
294 visitor(virtual_call) \
295 visitor(opt_virtual_call) \
296 visitor(static_call) \
297 visitor(static_stub) \
298 visitor(runtime_call) \
299 visitor(external_word) \
300 visitor(internal_word) \
301 visitor(poll) \
302 visitor(poll_return) \
303 visitor(breakpoint) \
304 visitor(section_word) \
305
306
307 public:
308 enum {
309 value_width = sizeof(unsigned short) * BitsPerByte,
310 type_width = 4, // == log2(type_mask+1)
311 nontype_width = value_width - type_width,
312 datalen_width = nontype_width-1,
313 datalen_tag = 1 << datalen_width, // or-ed into _value
314 datalen_limit = 1 << datalen_width,
315 datalen_mask = (1 << datalen_width)-1
316 };
317
318 // accessors
319 public:
320 relocType type() const { return (relocType)((unsigned)_value >> nontype_width); }
321 int format() const { return format_mask==0? 0: format_mask &
322 ((unsigned)_value >> offset_width); }
323 int addr_offset() const { assert(!is_prefix(), "must have offset");
324 return (_value & offset_mask)*offset_unit; }
325
326 protected:
327 const short* data() const { assert(is_datalen(), "must have data");
328 return (const short*)(this + 1); }
329 int datalen() const { assert(is_datalen(), "must have data");
330 return (_value & datalen_mask); }
331 int immediate() const { assert(is_immediate(), "must have immed");
332 return (_value & datalen_mask); }
333 public:
334 static int addr_unit() { return offset_unit; }
335 static int offset_limit() { return (1 << offset_width) * offset_unit; }
336
337 void set_type(relocType type);
338 void set_format(int format);
339
340 void remove() { set_type(none); }
341
342 protected:
343 bool is_none() const { return type() == none; }
344 bool is_prefix() const { return type() == data_prefix_tag; }
345 bool is_datalen() const { assert(is_prefix(), "must be prefix");
346 return (_value & datalen_tag) != 0; }
347 bool is_immediate() const { assert(is_prefix(), "must be prefix");
348 return (_value & datalen_tag) == 0; }
349
350 public:
351 // Occasionally records of type relocInfo::none will appear in the stream.
352 // We do not bother to filter these out, but clients should ignore them.
353 // These records serve as "filler" in three ways:
354 // - to skip large spans of unrelocated code (this is rare)
355 // - to pad out the relocInfo array to the required oop alignment
356 // - to disable old relocation information which is no longer applicable
357
358 inline friend relocInfo filler_relocInfo();
359
360 // Every non-prefix relocation may be preceded by at most one prefix,
361 // which supplies 1 or more halfwords of associated data. Conventionally,
362 // an int is represented by 0, 1, or 2 halfwords, depending on how
363 // many bits are required to represent the value. (In addition,
364 // if the sole halfword is a 10-bit unsigned number, it is made
365 // "immediate" in the prefix header word itself. This optimization
366 // is invisible outside this module.)
367
368 inline friend relocInfo prefix_relocInfo(int datalen = 0);
369
370 protected:
371 // an immediate relocInfo optimizes a prefix with one 10-bit unsigned value
372 static relocInfo immediate_relocInfo(int data0) {
373 assert(fits_into_immediate(data0), "data0 in limits");
374 return relocInfo(relocInfo::data_prefix_tag, RAW_BITS, data0);
375 }
376 static bool fits_into_immediate(int data0) {
377 return (data0 >= 0 && data0 < datalen_limit);
378 }
379
380 public:
381 // Support routines for compilers.
382
383 // This routine takes an infant relocInfo (unprefixed) and
384 // edits in its prefix, if any. It also updates dest.locs_end.
385 void initialize(CodeSection* dest, Relocation* reloc);
386
387 // This routine updates a prefix and returns the limit pointer.
388 // It tries to compress the prefix from 32 to 16 bits, and if
389 // successful returns a reduced "prefix_limit" pointer.
390 relocInfo* finish_prefix(short* prefix_limit);
391
392 // bit-packers for the data array:
393
394 // As it happens, the bytes within the shorts are ordered natively,
395 // but the shorts within the word are ordered big-endian.
396 // This is an arbitrary choice, made this way mainly to ease debugging.
397 static int data0_from_int(jint x) { return x >> value_width; }
398 static int data1_from_int(jint x) { return (short)x; }
399 static jint jint_from_data(short* data) {
400 return (data[0] << value_width) + (unsigned short)data[1];
401 }
402
403 static jint short_data_at(int n, short* data, int datalen) {
404 return datalen > n ? data[n] : 0;
405 }
406
407 static jint jint_data_at(int n, short* data, int datalen) {
408 return datalen > n+1 ? jint_from_data(&data[n]) : short_data_at(n, data, datalen);
409 }
410
411 // Update methods for relocation information
412 // (since code is dynamically patched, we also need to dynamically update the relocation info)
413 // Both methods takes old_type, so it is able to performe sanity checks on the information removed.
414 static void change_reloc_info_for_address(RelocIterator *itr, address pc, relocType old_type, relocType new_type);
415 static void remove_reloc_info_for_address(RelocIterator *itr, address pc, relocType old_type);
416
417 // Machine dependent stuff
418 #include "incls/_relocInfo_pd.hpp.incl"
419
420 protected:
421 // Derived constant, based on format_width which is PD:
422 enum {
423 offset_width = nontype_width - format_width,
424 offset_mask = (1<<offset_width) - 1,
425 format_mask = (1<<format_width) - 1
426 };
427 public:
428 enum {
429 // Conservatively large estimate of maximum length (in shorts)
430 // of any relocation record (probably breakpoints are largest).
431 // Extended format is length prefix, data words, and tag/offset suffix.
432 length_limit = 1 + 1 + (3*BytesPerWord/BytesPerShort) + 1,
433 have_format = format_width > 0
434 };
435 };
436
437 #define FORWARD_DECLARE_EACH_CLASS(name) \
438 class name##_Relocation;
439 APPLY_TO_RELOCATIONS(FORWARD_DECLARE_EACH_CLASS)
440 #undef FORWARD_DECLARE_EACH_CLASS
441
442
443
444 inline relocInfo filler_relocInfo() {
445 return relocInfo(relocInfo::none, relocInfo::offset_limit() - relocInfo::offset_unit);
446 }
447
448 inline relocInfo prefix_relocInfo(int datalen) {
449 assert(relocInfo::fits_into_immediate(datalen), "datalen in limits");
450 return relocInfo(relocInfo::data_prefix_tag, relocInfo::RAW_BITS, relocInfo::datalen_tag | datalen);
451 }
452
453
454 // Holder for flyweight relocation objects.
455 // Although the flyweight subclasses are of varying sizes,
456 // the holder is "one size fits all".
457 class RelocationHolder VALUE_OBJ_CLASS_SPEC {
458 friend class Relocation;
459 friend class CodeSection;
460
461 private:
462 // this preallocated memory must accommodate all subclasses of Relocation
463 // (this number is assertion-checked in Relocation::operator new)
464 enum { _relocbuf_size = 5 };
465 void* _relocbuf[ _relocbuf_size ];
466
467 public:
468 Relocation* reloc() const { return (Relocation*) &_relocbuf[0]; }
469 inline relocInfo::relocType type() const;
470
471 // Add a constant offset to a relocation. Helper for class Address.
472 RelocationHolder plus(int offset) const;
473
474 inline RelocationHolder(); // initializes type to none
475
476 inline RelocationHolder(Relocation* r); // make a copy
477
478 static const RelocationHolder none;
479 };
480
481 // A RelocIterator iterates through the relocation information of a CodeBlob.
482 // It is a variable BoundRelocation which is able to take on successive
483 // values as it is advanced through a code stream.
484 // Usage:
485 // RelocIterator iter(nm);
486 // while (iter.next()) {
487 // iter.reloc()->some_operation();
488 // }
489 // or:
490 // RelocIterator iter(nm);
491 // while (iter.next()) {
492 // switch (iter.type()) {
493 // case relocInfo::oop_type :
494 // case relocInfo::ic_type :
495 // case relocInfo::prim_type :
496 // case relocInfo::uncommon_type :
497 // case relocInfo::runtime_call_type :
498 // case relocInfo::internal_word_type:
499 // case relocInfo::external_word_type:
500 // ...
501 // }
502 // }
503
504 class RelocIterator : public StackObj {
505 enum { SECT_CONSTS = 2,
506 SECT_LIMIT = 3 }; // must be equal to CodeBuffer::SECT_LIMIT
507 friend class Relocation;
508 friend class relocInfo; // for change_reloc_info_for_address only
509 typedef relocInfo::relocType relocType;
510
511 private:
512 address _limit; // stop producing relocations after this _addr
513 relocInfo* _current; // the current relocation information
514 relocInfo* _end; // end marker; we're done iterating when _current == _end
515 nmethod* _code; // compiled method containing _addr
516 address _addr; // instruction to which the relocation applies
517 short _databuf; // spare buffer for compressed data
518 short* _data; // pointer to the relocation's data
519 short _datalen; // number of halfwords in _data
520 char _format; // position within the instruction
521
522 // Base addresses needed to compute targets of section_word_type relocs.
523 address _section_start[SECT_LIMIT];
524
525 void set_has_current(bool b) {
526 _datalen = !b ? -1 : 0;
527 debug_only(_data = NULL);
528 }
529 void set_current(relocInfo& ri) {
530 _current = &ri;
531 set_has_current(true);
532 }
533
534 RelocationHolder _rh; // where the current relocation is allocated
535
536 relocInfo* current() const { assert(has_current(), "must have current");
537 return _current; }
538
539 void set_limits(address begin, address limit);
540
541 void advance_over_prefix(); // helper method
542
543 void initialize_misc() {
544 set_has_current(false);
545 for (int i = 0; i < SECT_LIMIT; i++) {
546 _section_start[i] = NULL; // these will be lazily computed, if needed
547 }
548 }
549
550 address compute_section_start(int n) const; // out-of-line helper
551
552 void initialize(nmethod* nm, address begin, address limit);
553
554 friend class PatchingRelocIterator;
555 // make an uninitialized one, for PatchingRelocIterator:
556 RelocIterator() { initialize_misc(); }
557
558 public:
559 // constructor
560 RelocIterator(nmethod* nm, address begin = NULL, address limit = NULL);
561 RelocIterator(CodeSection* cb, address begin = NULL, address limit = NULL);
562
563 // get next reloc info, return !eos
564 bool next() {
565 _current++;
566 assert(_current <= _end, "must not overrun relocInfo");
567 if (_current == _end) {
568 set_has_current(false);
569 return false;
570 }
571 set_has_current(true);
572
573 if (_current->is_prefix()) {
574 advance_over_prefix();
575 assert(!current()->is_prefix(), "only one prefix at a time");
576 }
577
578 _addr += _current->addr_offset();
579
580 if (_limit != NULL && _addr >= _limit) {
581 set_has_current(false);
582 return false;
583 }
584
585 if (relocInfo::have_format) _format = current()->format();
586 return true;
587 }
588
589 // accessors
590 address limit() const { return _limit; }
591 void set_limit(address x);
592 relocType type() const { return current()->type(); }
593 int format() const { return (relocInfo::have_format) ? current()->format() : 0; }
594 address addr() const { return _addr; }
595 nmethod* code() const { return _code; }
596 short* data() const { return _data; }
597 int datalen() const { return _datalen; }
598 bool has_current() const { return _datalen >= 0; }
599
600 void set_addr(address addr) { _addr = addr; }
601 bool addr_in_const() const { return addr() >= section_start(SECT_CONSTS); }
602
603 address section_start(int n) const {
604 address res = _section_start[n];
605 return (res != NULL) ? res : compute_section_start(n);
606 }
607
608 // The address points to the affected displacement part of the instruction.
609 // For RISC, this is just the whole instruction.
610 // For Intel, this is an unaligned 32-bit word.
611
612 // type-specific relocation accessors: oop_Relocation* oop_reloc(), etc.
613 #define EACH_TYPE(name) \
614 inline name##_Relocation* name##_reloc();
615 APPLY_TO_RELOCATIONS(EACH_TYPE)
616 #undef EACH_TYPE
617 // generic relocation accessor; switches on type to call the above
618 Relocation* reloc();
619
620 // CodeBlob's have relocation indexes for faster random access:
621 static int locs_and_index_size(int code_size, int locs_size);
622 // Store an index into [dest_start+dest_count..dest_end).
623 // At dest_start[0..dest_count] is the actual relocation information.
624 // Everything else up to dest_end is free space for the index.
625 static void create_index(relocInfo* dest_begin, int dest_count, relocInfo* dest_end);
626
627 #ifndef PRODUCT
628 public:
629 void print();
630 void print_current();
631 #endif
632 };
633
634
635 // A Relocation is a flyweight object allocated within a RelocationHolder.
636 // It represents the relocation data of relocation record.
637 // So, the RelocIterator unpacks relocInfos into Relocations.
638
639 class Relocation VALUE_OBJ_CLASS_SPEC {
640 friend class RelocationHolder;
641 friend class RelocIterator;
642
643 private:
644 static void guarantee_size();
645
646 // When a relocation has been created by a RelocIterator,
647 // this field is non-null. It allows the relocation to know
648 // its context, such as the address to which it applies.
649 RelocIterator* _binding;
650
651 protected:
652 RelocIterator* binding() const {
653 assert(_binding != NULL, "must be bound");
654 return _binding;
655 }
656 void set_binding(RelocIterator* b) {
657 assert(_binding == NULL, "must be unbound");
658 _binding = b;
659 assert(_binding != NULL, "must now be bound");
660 }
661
662 Relocation() {
663 _binding = NULL;
664 }
665
666 static RelocationHolder newHolder() {
667 return RelocationHolder();
668 }
669
670 public:
671 void* operator new(size_t size, const RelocationHolder& holder) {
672 if (size > sizeof(holder._relocbuf)) guarantee_size();
673 assert((void* const *)holder.reloc() == &holder._relocbuf[0], "ptrs must agree");
674 return holder.reloc();
675 }
676
677 // make a generic relocation for a given type (if possible)
678 static RelocationHolder spec_simple(relocInfo::relocType rtype);
679
680 // here is the type-specific hook which writes relocation data:
681 virtual void pack_data_to(CodeSection* dest) { }
682
683 // here is the type-specific hook which reads (unpacks) relocation data:
684 virtual void unpack_data() {
685 assert(datalen()==0 || type()==relocInfo::none, "no data here");
686 }
687
688 protected:
689 // Helper functions for pack_data_to() and unpack_data().
690
691 // Most of the compression logic is confined here.
692 // (The "immediate data" mechanism of relocInfo works independently
693 // of this stuff, and acts to further compress most 1-word data prefixes.)
694
695 // A variable-width int is encoded as a short if it will fit in 16 bits.
696 // The decoder looks at datalen to decide whether to unpack short or jint.
697 // Most relocation records are quite simple, containing at most two ints.
698
699 static bool is_short(jint x) { return x == (short)x; }
700 static short* add_short(short* p, int x) { *p++ = x; return p; }
701 static short* add_jint (short* p, jint x) {
702 *p++ = relocInfo::data0_from_int(x); *p++ = relocInfo::data1_from_int(x);
703 return p;
704 }
705 static short* add_var_int(short* p, jint x) { // add a variable-width int
706 if (is_short(x)) p = add_short(p, x);
707 else p = add_jint (p, x);
708 return p;
709 }
710
711 static short* pack_1_int_to(short* p, jint x0) {
712 // Format is one of: [] [x] [Xx]
713 if (x0 != 0) p = add_var_int(p, x0);
714 return p;
715 }
716 int unpack_1_int() {
717 assert(datalen() <= 2, "too much data");
718 return relocInfo::jint_data_at(0, data(), datalen());
719 }
720
721 // With two ints, the short form is used only if both ints are short.
722 short* pack_2_ints_to(short* p, jint x0, jint x1) {
723 // Format is one of: [] [x y?] [Xx Y?y]
724 if (x0 == 0 && x1 == 0) {
725 // no halfwords needed to store zeroes
726 } else if (is_short(x0) && is_short(x1)) {
727 // 1-2 halfwords needed to store shorts
728 p = add_short(p, x0); if (x1!=0) p = add_short(p, x1);
729 } else {
730 // 3-4 halfwords needed to store jints
731 p = add_jint(p, x0); p = add_var_int(p, x1);
732 }
733 return p;
734 }
735 void unpack_2_ints(jint& x0, jint& x1) {
736 int dlen = datalen();
737 short* dp = data();
738 if (dlen <= 2) {
739 x0 = relocInfo::short_data_at(0, dp, dlen);
740 x1 = relocInfo::short_data_at(1, dp, dlen);
741 } else {
742 assert(dlen <= 4, "too much data");
743 x0 = relocInfo::jint_data_at(0, dp, dlen);
744 x1 = relocInfo::jint_data_at(2, dp, dlen);
745 }
746 }
747
748 protected:
749 // platform-dependent utilities for decoding and patching instructions
750 void pd_set_data_value (address x, intptr_t off); // a set or mem-ref
751 address pd_call_destination (address orig_addr = NULL);
752 void pd_set_call_destination (address x);
753 void pd_swap_in_breakpoint (address x, short* instrs, int instrlen);
754 void pd_swap_out_breakpoint (address x, short* instrs, int instrlen);
755 static int pd_breakpoint_size ();
756
757 // this extracts the address of an address in the code stream instead of the reloc data
758 address* pd_address_in_code ();
759
760 // this extracts an address from the code stream instead of the reloc data
761 address pd_get_address_from_code ();
762
763 // these convert from byte offsets, to scaled offsets, to addresses
764 static jint scaled_offset(address x, address base) {
765 int byte_offset = x - base;
766 int offset = -byte_offset / relocInfo::addr_unit();
767 assert(address_from_scaled_offset(offset, base) == x, "just checkin'");
768 return offset;
769 }
770 static jint scaled_offset_null_special(address x, address base) {
771 // Some relocations treat offset=0 as meaning NULL.
772 // Handle this extra convention carefully.
773 if (x == NULL) return 0;
774 assert(x != base, "offset must not be zero");
775 return scaled_offset(x, base);
776 }
777 static address address_from_scaled_offset(jint offset, address base) {
778 int byte_offset = -( offset * relocInfo::addr_unit() );
779 return base + byte_offset;
780 }
781
782 // these convert between indexes and addresses in the runtime system
783 static int32_t runtime_address_to_index(address runtime_address);
784 static address index_to_runtime_address(int32_t index);
785
786 // helpers for mapping between old and new addresses after a move or resize
787 address old_addr_for(address newa, const CodeBuffer* src, CodeBuffer* dest);
788 address new_addr_for(address olda, const CodeBuffer* src, CodeBuffer* dest);
789 void normalize_address(address& addr, const CodeSection* dest, bool allow_other_sections = false);
790
791 public:
792 // accessors which only make sense for a bound Relocation
793 address addr() const { return binding()->addr(); }
794 nmethod* code() const { return binding()->code(); }
795 bool addr_in_const() const { return binding()->addr_in_const(); }
796 protected:
797 short* data() const { return binding()->data(); }
798 int datalen() const { return binding()->datalen(); }
799 int format() const { return binding()->format(); }
800
801 public:
802 virtual relocInfo::relocType type() { return relocInfo::none; }
803
804 // is it a call instruction?
805 virtual bool is_call() { return false; }
806
807 // is it a data movement instruction?
808 virtual bool is_data() { return false; }
809
810 // some relocations can compute their own values
811 virtual address value();
812
813 // all relocations are able to reassert their values
814 virtual void set_value(address x);
815
816 virtual void clear_inline_cache() { }
817
818 // This method assumes that all virtual/static (inline) caches are cleared (since for static_call_type and
819 // ic_call_type is not always posisition dependent (depending on the state of the cache)). However, this is
820 // probably a reasonable assumption, since empty caches simplifies code reloacation.
821 virtual void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest) { }
822
823 void print();
824 };
825
826
827 // certain inlines must be deferred until class Relocation is defined:
828
829 inline RelocationHolder::RelocationHolder() {
830 // initialize the vtbl, just to keep things type-safe
831 new(*this) Relocation();
832 }
833
834
835 inline RelocationHolder::RelocationHolder(Relocation* r) {
836 // wordwise copy from r (ok if it copies garbage after r)
837 for (int i = 0; i < _relocbuf_size; i++) {
838 _relocbuf[i] = ((void**)r)[i];
839 }
840 }
841
842
843 relocInfo::relocType RelocationHolder::type() const {
844 return reloc()->type();
845 }
846
847 // A DataRelocation always points at a memory or load-constant instruction..
848 // It is absolute on most machines, and the constant is split on RISCs.
849 // The specific subtypes are oop, external_word, and internal_word.
850 // By convention, the "value" does not include a separately reckoned "offset".
851 class DataRelocation : public Relocation {
852 public:
853 bool is_data() { return true; }
854
855 // both target and offset must be computed somehow from relocation data
856 virtual int offset() { return 0; }
857 address value() = 0;
858 void set_value(address x) { set_value(x, offset()); }
859 void set_value(address x, intptr_t o) {
860 if (addr_in_const())
861 *(address*)addr() = x;
862 else
863 pd_set_data_value(x, o);
864 }
865
866 // The "o" (displacement) argument is relevant only to split relocations
867 // on RISC machines. In some CPUs (SPARC), the set-hi and set-lo ins'ns
868 // can encode more than 32 bits between them. This allows compilers to
869 // share set-hi instructions between addresses that differ by a small
870 // offset (e.g., different static variables in the same class).
871 // On such machines, the "x" argument to set_value on all set-lo
872 // instructions must be the same as the "x" argument for the
873 // corresponding set-hi instructions. The "o" arguments for the
874 // set-hi instructions are ignored, and must not affect the high-half
875 // immediate constant. The "o" arguments for the set-lo instructions are
876 // added into the low-half immediate constant, and must not overflow it.
877 };
878
879 // A CallRelocation always points at a call instruction.
880 // It is PC-relative on most machines.
881 class CallRelocation : public Relocation {
882 public:
883 bool is_call() { return true; }
884
885 address destination() { return pd_call_destination(); }
886 void set_destination(address x); // pd_set_call_destination
887
888 void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest);
889 address value() { return destination(); }
890 void set_value(address x) { set_destination(x); }
891 };
892
893 class oop_Relocation : public DataRelocation {
894 relocInfo::relocType type() { return relocInfo::oop_type; }
895
896 public:
897 // encode in one of these formats: [] [n] [n l] [Nn l] [Nn Ll]
898 // an oop in the CodeBlob's oop pool
899 static RelocationHolder spec(int oop_index, int offset = 0) {
900 assert(oop_index > 0, "must be a pool-resident oop");
901 RelocationHolder rh = newHolder();
902 new(rh) oop_Relocation(oop_index, offset);
903 return rh;
904 }
905 // an oop in the instruction stream
906 static RelocationHolder spec_for_immediate() {
907 const int oop_index = 0;
908 const int offset = 0; // if you want an offset, use the oop pool
909 RelocationHolder rh = newHolder();
910 new(rh) oop_Relocation(oop_index, offset);
911 return rh;
912 }
913
914 private:
915 jint _oop_index; // if > 0, index into CodeBlob::oop_at
916 jint _offset; // byte offset to apply to the oop itself
917
918 oop_Relocation(int oop_index, int offset) {
919 _oop_index = oop_index; _offset = offset;
920 }
921
922 friend class RelocIterator;
923 oop_Relocation() { }
924
925 public:
926 int oop_index() { return _oop_index; }
927 int offset() { return _offset; }
928
929 // data is packed in "2_ints" format: [i o] or [Ii Oo]
930 void pack_data_to(CodeSection* dest);
931 void unpack_data();
932
933 void fix_oop_relocation(); // reasserts oop value
934
935 address value() { return (address) *oop_addr(); }
936
937 bool oop_is_immediate() { return oop_index() == 0; }
938
939 oop* oop_addr(); // addr or &pool[jint_data]
940 oop oop_value(); // *oop_addr
941 // Note: oop_value transparently converts Universe::non_oop_word to NULL.
942 };
943
944 class virtual_call_Relocation : public CallRelocation {
945 relocInfo::relocType type() { return relocInfo::virtual_call_type; }
946
947 public:
948 // "first_oop" points to the first associated set-oop.
949 // The oop_limit helps find the last associated set-oop.
950 // (See comments at the top of this file.)
951 static RelocationHolder spec(address first_oop, address oop_limit = NULL) {
952 RelocationHolder rh = newHolder();
953 new(rh) virtual_call_Relocation(first_oop, oop_limit);
954 return rh;
955 }
956
957 virtual_call_Relocation(address first_oop, address oop_limit) {
958 _first_oop = first_oop; _oop_limit = oop_limit;
959 assert(first_oop != NULL, "first oop address must be specified");
960 }
961
962 private:
963 address _first_oop; // location of first set-oop instruction
964 address _oop_limit; // search limit for set-oop instructions
965
966 friend class RelocIterator;
967 virtual_call_Relocation() { }
968
969
970 public:
971 address first_oop();
972 address oop_limit();
973
974 // data is packed as scaled offsets in "2_ints" format: [f l] or [Ff Ll]
975 // oop_limit is set to 0 if the limit falls somewhere within the call.
976 // When unpacking, a zero oop_limit is taken to refer to the end of the call.
977 // (This has the effect of bringing in the call's delay slot on SPARC.)
978 void pack_data_to(CodeSection* dest);
979 void unpack_data();
980
981 void clear_inline_cache();
982
983 // Figure out where an ic_call is hiding, given a set-oop or call.
984 // Either ic_call or first_oop must be non-null; the other is deduced.
985 // Code if non-NULL must be the nmethod, else it is deduced.
986 // The address of the patchable oop is also deduced.
987 // The returned iterator will enumerate over the oops and the ic_call,
988 // as well as any other relocations that happen to be in that span of code.
989 // Recognize relevant set_oops with: oop_reloc()->oop_addr() == oop_addr.
990 static RelocIterator parse_ic(nmethod* &nm, address &ic_call, address &first_oop, oop* &oop_addr, bool *is_optimized);
991 };
992
993
994 class opt_virtual_call_Relocation : public CallRelocation {
995 relocInfo::relocType type() { return relocInfo::opt_virtual_call_type; }
996
997 public:
998 static RelocationHolder spec() {
999 RelocationHolder rh = newHolder();
1000 new(rh) opt_virtual_call_Relocation();
1001 return rh;
1002 }
1003
1004 private:
1005 friend class RelocIterator;
1006 opt_virtual_call_Relocation() { }
1007
1008 public:
1009 void clear_inline_cache();
1010
1011 // find the matching static_stub
1012 address static_stub();
1013 };
1014
1015
1016 class static_call_Relocation : public CallRelocation {
1017 relocInfo::relocType type() { return relocInfo::static_call_type; }
1018
1019 public:
1020 static RelocationHolder spec() {
1021 RelocationHolder rh = newHolder();
1022 new(rh) static_call_Relocation();
1023 return rh;
1024 }
1025
1026 private:
1027 friend class RelocIterator;
1028 static_call_Relocation() { }
1029
1030 public:
1031 void clear_inline_cache();
1032
1033 // find the matching static_stub
1034 address static_stub();
1035 };
1036
1037 class static_stub_Relocation : public Relocation {
1038 relocInfo::relocType type() { return relocInfo::static_stub_type; }
1039
1040 public:
1041 static RelocationHolder spec(address static_call) {
1042 RelocationHolder rh = newHolder();
1043 new(rh) static_stub_Relocation(static_call);
1044 return rh;
1045 }
1046
1047 private:
1048 address _static_call; // location of corresponding static_call
1049
1050 static_stub_Relocation(address static_call) {
1051 _static_call = static_call;
1052 }
1053
1054 friend class RelocIterator;
1055 static_stub_Relocation() { }
1056
1057 public:
1058 void clear_inline_cache();
1059
1060 address static_call() { return _static_call; }
1061
1062 // data is packed as a scaled offset in "1_int" format: [c] or [Cc]
1063 void pack_data_to(CodeSection* dest);
1064 void unpack_data();
1065 };
1066
1067 class runtime_call_Relocation : public CallRelocation {
1068 relocInfo::relocType type() { return relocInfo::runtime_call_type; }
1069
1070 public:
1071 static RelocationHolder spec() {
1072 RelocationHolder rh = newHolder();
1073 new(rh) runtime_call_Relocation();
1074 return rh;
1075 }
1076
1077 private:
1078 friend class RelocIterator;
1079 runtime_call_Relocation() { }
1080
1081 public:
1082 };
1083
1084 class external_word_Relocation : public DataRelocation {
1085 relocInfo::relocType type() { return relocInfo::external_word_type; }
1086
1087 public:
1088 static RelocationHolder spec(address target) {
1089 assert(target != NULL, "must not be null");
1090 RelocationHolder rh = newHolder();
1091 new(rh) external_word_Relocation(target);
1092 return rh;
1093 }
1094
1095 // Use this one where all 32/64 bits of the target live in the code stream.
1096 // The target must be an intptr_t, and must be absolute (not relative).
1097 static RelocationHolder spec_for_immediate() {
1098 RelocationHolder rh = newHolder();
1099 new(rh) external_word_Relocation(NULL);
1100 return rh;
1101 }
1102
1103 private:
1104 address _target; // address in runtime
1105
1106 external_word_Relocation(address target) {
1107 _target = target;
1108 }
1109
1110 friend class RelocIterator;
1111 external_word_Relocation() { }
1112
1113 public:
1114 // data is packed as a well-known address in "1_int" format: [a] or [Aa]
1115 // The function runtime_address_to_index is used to turn full addresses
1116 // to short indexes, if they are pre-registered by the stub mechanism.
1117 // If the "a" value is 0 (i.e., _target is NULL), the address is stored
1118 // in the code stream. See external_word_Relocation::target().
1119 void pack_data_to(CodeSection* dest);
1120 void unpack_data();
1121
1122 void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest);
1123 address target(); // if _target==NULL, fetch addr from code stream
1124 address value() { return target(); }
1125 };
1126
1127 class internal_word_Relocation : public DataRelocation {
1128 relocInfo::relocType type() { return relocInfo::internal_word_type; }
1129
1130 public:
1131 static RelocationHolder spec(address target) {
1132 assert(target != NULL, "must not be null");
1133 RelocationHolder rh = newHolder();
1134 new(rh) internal_word_Relocation(target);
1135 return rh;
1136 }
1137
1138 // use this one where all the bits of the target can fit in the code stream:
1139 static RelocationHolder spec_for_immediate() {
1140 RelocationHolder rh = newHolder();
1141 new(rh) internal_word_Relocation(NULL);
1142 return rh;
1143 }
1144
1145 internal_word_Relocation(address target) {
1146 _target = target;
1147 _section = -1; // self-relative
1148 }
1149
1150 protected:
1151 address _target; // address in CodeBlob
1152 int _section; // section providing base address, if any
1153
1154 friend class RelocIterator;
1155 internal_word_Relocation() { }
1156
1157 // bit-width of LSB field in packed offset, if section >= 0
1158 enum { section_width = 2 }; // must equal CodeBuffer::sect_bits
1159
1160 public:
1161 // data is packed as a scaled offset in "1_int" format: [o] or [Oo]
1162 // If the "o" value is 0 (i.e., _target is NULL), the offset is stored
1163 // in the code stream. See internal_word_Relocation::target().
1164 // If _section is not -1, it is appended to the low bits of the offset.
1165 void pack_data_to(CodeSection* dest);
1166 void unpack_data();
1167
1168 void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest);
1169 address target(); // if _target==NULL, fetch addr from code stream
1170 int section() { return _section; }
1171 address value() { return target(); }
1172 };
1173
1174 class section_word_Relocation : public internal_word_Relocation {
1175 relocInfo::relocType type() { return relocInfo::section_word_type; }
1176
1177 public:
1178 static RelocationHolder spec(address target, int section) {
1179 RelocationHolder rh = newHolder();
1180 new(rh) section_word_Relocation(target, section);
1181 return rh;
1182 }
1183
1184 section_word_Relocation(address target, int section) {
1185 assert(target != NULL, "must not be null");
1186 assert(section >= 0, "must be a valid section");
1187 _target = target;
1188 _section = section;
1189 }
1190
1191 //void pack_data_to -- inherited
1192 void unpack_data();
1193
1194 private:
1195 friend class RelocIterator;
1196 section_word_Relocation() { }
1197 };
1198
1199
1200 class poll_Relocation : public Relocation {
1201 bool is_data() { return true; }
1202 relocInfo::relocType type() { return relocInfo::poll_type; }
1203 void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest);
1204 };
1205
1206 class poll_return_Relocation : public Relocation {
1207 bool is_data() { return true; }
1208 relocInfo::relocType type() { return relocInfo::poll_return_type; }
1209 void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest);
1210 };
1211
1212
1213 class breakpoint_Relocation : public Relocation {
1214 relocInfo::relocType type() { return relocInfo::breakpoint_type; }
1215
1216 enum {
1217 // attributes which affect the interpretation of the data:
1218 removable_attr = 0x0010, // buffer [i...] allows for undoing the trap
1219 internal_attr = 0x0020, // the target is an internal addr (local stub)
1220 settable_attr = 0x0040, // the target is settable
1221
1222 // states which can change over time:
1223 enabled_state = 0x0100, // breakpoint must be active in running code
1224 active_state = 0x0200, // breakpoint instruction actually in code
1225
1226 kind_mask = 0x000F, // mask for extracting kind
1227 high_bit = 0x4000 // extra bit which is always set
1228 };
1229
1230 public:
1231 enum {
1232 // kinds:
1233 initialization = 1,
1234 safepoint = 2
1235 };
1236
1237 // If target is NULL, 32 bits are reserved for a later set_target().
1238 static RelocationHolder spec(int kind, address target = NULL, bool internal_target = false) {
1239 RelocationHolder rh = newHolder();
1240 new(rh) breakpoint_Relocation(kind, target, internal_target);
1241 return rh;
1242 }
1243
1244 private:
1245 // We require every bits value to NOT to fit into relocInfo::datalen_width,
1246 // because we are going to actually store state in the reloc, and so
1247 // cannot allow it to be compressed (and hence copied by the iterator).
1248
1249 short _bits; // bit-encoded kind, attrs, & state
1250 address _target;
1251
1252 breakpoint_Relocation(int kind, address target, bool internal_target);
1253
1254 friend class RelocIterator;
1255 breakpoint_Relocation() { }
1256
1257 short bits() const { return _bits; }
1258 short& live_bits() const { return data()[0]; }
1259 short* instrs() const { return data() + datalen() - instrlen(); }
1260 int instrlen() const { return removable() ? pd_breakpoint_size() : 0; }
1261
1262 void set_bits(short x) {
1263 assert(live_bits() == _bits, "must be the only mutator of reloc info");
1264 live_bits() = _bits = x;
1265 }
1266
1267 public:
1268 address target() const;
1269 void set_target(address x);
1270
1271 int kind() const { return bits() & kind_mask; }
1272 bool enabled() const { return (bits() & enabled_state) != 0; }
1273 bool active() const { return (bits() & active_state) != 0; }
1274 bool internal() const { return (bits() & internal_attr) != 0; }
1275 bool removable() const { return (bits() & removable_attr) != 0; }
1276 bool settable() const { return (bits() & settable_attr) != 0; }
1277
1278 void set_enabled(bool b); // to activate, you must also say set_active
1279 void set_active(bool b); // actually inserts bpt (must be enabled 1st)
1280
1281 // data is packed as 16 bits, followed by the target (1 or 2 words), followed
1282 // if necessary by empty storage for saving away original instruction bytes.
1283 void pack_data_to(CodeSection* dest);
1284 void unpack_data();
1285
1286 // during certain operations, breakpoints must be out of the way:
1287 void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest) {
1288 assert(!active(), "cannot perform relocation on enabled breakpoints");
1289 }
1290 };
1291
1292
1293 // We know all the xxx_Relocation classes, so now we can define these:
1294 #define EACH_CASE(name) \
1295 inline name##_Relocation* RelocIterator::name##_reloc() { \
1296 assert(type() == relocInfo::name##_type, "type must agree"); \
1297 /* The purpose of the placed "new" is to re-use the same */ \
1298 /* stack storage for each new iteration. */ \
1299 name##_Relocation* r = new(_rh) name##_Relocation(); \
1300 r->set_binding(this); \
1301 r->name##_Relocation::unpack_data(); \
1302 return r; \
1303 }
1304 APPLY_TO_RELOCATIONS(EACH_CASE);
1305 #undef EACH_CASE
1306
1307 inline RelocIterator::RelocIterator(nmethod* nm, address begin, address limit) {
1308 initialize(nm, begin, limit);
1309 }
1310
1311 // if you are going to patch code, you should use this subclass of
1312 // RelocIterator
1313 class PatchingRelocIterator : public RelocIterator {
1314 private:
1315 RelocIterator _init_state;
1316
1317 void prepass(); // deactivates all breakpoints
1318 void postpass(); // reactivates all enabled breakpoints
1319
1320 // do not copy these puppies; it would have unpredictable side effects
1321 // these are private and have no bodies defined because they should not be called
1322 PatchingRelocIterator(const RelocIterator&);
1323 void operator=(const RelocIterator&);
1324
1325 public:
1326 PatchingRelocIterator(nmethod* nm, address begin = NULL, address limit = NULL)
1327 : RelocIterator(nm, begin, limit) { prepass(); }
1328
1329 ~PatchingRelocIterator() { postpass(); }
1330 };