Sat, 01 Sep 2012 13:25:18 -0400
6964458: Reimplement class meta-data storage to use native memory
Summary: Remove PermGen, allocate meta-data in metaspace linked to class loaders, rewrite GC walking, rewrite and rename metadata to be C++ classes
Reviewed-by: jmasa, stefank, never, coleenp, kvn, brutisso, mgerdin, dholmes, jrose, twisti, roland
Contributed-by: jmasa <jon.masamitsu@oracle.com>, stefank <stefan.karlsson@oracle.com>, mgerdin <mikael.gerdin@oracle.com>, never <tom.rodriguez@oracle.com>
1 /*
2 * Copyright (c) 1997, 2012, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
25 #ifndef SHARE_VM_CODE_RELOCINFO_HPP
26 #define SHARE_VM_CODE_RELOCINFO_HPP
28 #include "memory/allocation.hpp"
29 #include "utilities/top.hpp"
31 class NativeMovConstReg;
33 // Types in this file:
34 // relocInfo
35 // One element of an array of halfwords encoding compressed relocations.
36 // Also, the source of relocation types (relocInfo::oop_type, ...).
37 // Relocation
38 // A flyweight object representing a single relocation.
39 // It is fully unpacked from the compressed relocation array.
40 // metadata_Relocation, ... (subclasses of Relocation)
41 // The location of some type-specific operations (metadata_addr, ...).
42 // Also, the source of relocation specs (metadata_Relocation::spec, ...).
43 // oop_Relocation, ... (subclasses of Relocation)
44 // oops in the code stream (strings, class loaders)
45 // Also, the source of relocation specs (oop_Relocation::spec, ...).
46 // RelocationHolder
47 // A ValueObj type which acts as a union holding a Relocation object.
48 // Represents a relocation spec passed into a CodeBuffer during assembly.
49 // RelocIterator
50 // A StackObj which iterates over the relocations associated with
51 // a range of code addresses. Can be used to operate a copy of code.
52 // PatchingRelocIterator
53 // Specialized subtype of RelocIterator which removes breakpoints
54 // temporarily during iteration, then restores them.
55 // BoundRelocation
56 // An _internal_ type shared by packers and unpackers of relocations.
57 // It pastes together a RelocationHolder with some pointers into
58 // code and relocInfo streams.
61 // Notes on relocType:
62 //
63 // These hold enough information to read or write a value embedded in
64 // the instructions of an CodeBlob. They're used to update:
65 //
66 // 1) embedded oops (isOop() == true)
67 // 2) inline caches (isIC() == true)
68 // 3) runtime calls (isRuntimeCall() == true)
69 // 4) internal word ref (isInternalWord() == true)
70 // 5) external word ref (isExternalWord() == true)
71 //
72 // when objects move (GC) or if code moves (compacting the code heap).
73 // They are also used to patch the code (if a call site must change)
74 //
75 // A relocInfo is represented in 16 bits:
76 // 4 bits indicating the relocation type
77 // 12 bits indicating the offset from the previous relocInfo address
78 //
79 // The offsets accumulate along the relocInfo stream to encode the
80 // address within the CodeBlob, which is named RelocIterator::addr().
81 // The address of a particular relocInfo always points to the first
82 // byte of the relevant instruction (and not to any of its subfields
83 // or embedded immediate constants).
84 //
85 // The offset value is scaled appropriately for the target machine.
86 // (See relocInfo_<arch>.hpp for the offset scaling.)
87 //
88 // On some machines, there may also be a "format" field which may provide
89 // additional information about the format of the instruction stream
90 // at the corresponding code address. The format value is usually zero.
91 // Any machine (such as Intel) whose instructions can sometimes contain
92 // more than one relocatable constant needs format codes to distinguish
93 // which operand goes with a given relocation.
94 //
95 // If the target machine needs N format bits, the offset has 12-N bits,
96 // the format is encoded between the offset and the type, and the
97 // relocInfo_<arch>.hpp file has manifest constants for the format codes.
98 //
99 // If the type is "data_prefix_tag" then the offset bits are further encoded,
100 // and in fact represent not a code-stream offset but some inline data.
101 // The data takes the form of a counted sequence of halfwords, which
102 // precedes the actual relocation record. (Clients never see it directly.)
103 // The interpetation of this extra data depends on the relocation type.
104 //
105 // On machines that have 32-bit immediate fields, there is usually
106 // little need for relocation "prefix" data, because the instruction stream
107 // is a perfectly reasonable place to store the value. On machines in
108 // which 32-bit values must be "split" across instructions, the relocation
109 // data is the "true" specification of the value, which is then applied
110 // to some field of the instruction (22 or 13 bits, on SPARC).
111 //
112 // Whenever the location of the CodeBlob changes, any PC-relative
113 // relocations, and any internal_word_type relocations, must be reapplied.
114 // After the GC runs, oop_type relocations must be reapplied.
115 //
116 //
117 // Here are meanings of the types:
118 //
119 // relocInfo::none -- a filler record
120 // Value: none
121 // Instruction: The corresponding code address is ignored
122 // Data: Any data prefix and format code are ignored
123 // (This means that any relocInfo can be disabled by setting
124 // its type to none. See relocInfo::remove.)
125 //
126 // relocInfo::oop_type, relocInfo::metadata_type -- a reference to an oop or meta data
127 // Value: an oop, or else the address (handle) of an oop
128 // Instruction types: memory (load), set (load address)
129 // Data: [] an oop stored in 4 bytes of instruction
130 // [n] n is the index of an oop in the CodeBlob's oop pool
131 // [[N]n l] and l is a byte offset to be applied to the oop
132 // [Nn Ll] both index and offset may be 32 bits if necessary
133 // Here is a special hack, used only by the old compiler:
134 // [[N]n 00] the value is the __address__ of the nth oop in the pool
135 // (Note that the offset allows optimal references to class variables.)
136 //
137 // relocInfo::internal_word_type -- an address within the same CodeBlob
138 // relocInfo::section_word_type -- same, but can refer to another section
139 // Value: an address in the CodeBlob's code or constants section
140 // Instruction types: memory (load), set (load address)
141 // Data: [] stored in 4 bytes of instruction
142 // [[L]l] a relative offset (see [About Offsets] below)
143 // In the case of section_word_type, the offset is relative to a section
144 // base address, and the section number (e.g., SECT_INSTS) is encoded
145 // into the low two bits of the offset L.
146 //
147 // relocInfo::external_word_type -- a fixed address in the runtime system
148 // Value: an address
149 // Instruction types: memory (load), set (load address)
150 // Data: [] stored in 4 bytes of instruction
151 // [n] the index of a "well-known" stub (usual case on RISC)
152 // [Ll] a 32-bit address
153 //
154 // relocInfo::runtime_call_type -- a fixed subroutine in the runtime system
155 // Value: an address
156 // Instruction types: PC-relative call (or a PC-relative branch)
157 // Data: [] stored in 4 bytes of instruction
158 //
159 // relocInfo::static_call_type -- a static call
160 // Value: an CodeBlob, a stub, or a fixup routine
161 // Instruction types: a call
162 // Data: []
163 // The identity of the callee is extracted from debugging information.
164 // //%note reloc_3
165 //
166 // relocInfo::virtual_call_type -- a virtual call site (which includes an inline
167 // cache)
168 // Value: an CodeBlob, a stub, the interpreter, or a fixup routine
169 // Instruction types: a call, plus some associated set-oop instructions
170 // Data: [] the associated set-oops are adjacent to the call
171 // [n] n is a relative offset to the first set-oop
172 // [[N]n l] and l is a limit within which the set-oops occur
173 // [Nn Ll] both n and l may be 32 bits if necessary
174 // The identity of the callee is extracted from debugging information.
175 //
176 // relocInfo::opt_virtual_call_type -- a virtual call site that is statically bound
177 //
178 // Same info as a static_call_type. We use a special type, so the handling of
179 // virtuals and statics are separated.
180 //
181 //
182 // The offset n points to the first set-oop. (See [About Offsets] below.)
183 // In turn, the set-oop instruction specifies or contains an oop cell devoted
184 // exclusively to the IC call, which can be patched along with the call.
185 //
186 // The locations of any other set-oops are found by searching the relocation
187 // information starting at the first set-oop, and continuing until all
188 // relocations up through l have been inspected. The value l is another
189 // relative offset. (Both n and l are relative to the call's first byte.)
190 //
191 // The limit l of the search is exclusive. However, if it points within
192 // the call (e.g., offset zero), it is adjusted to point after the call and
193 // any associated machine-specific delay slot.
194 //
195 // Since the offsets could be as wide as 32-bits, these conventions
196 // put no restrictions whatever upon code reorganization.
197 //
198 // The compiler is responsible for ensuring that transition from a clean
199 // state to a monomorphic compiled state is MP-safe. This implies that
200 // the system must respond well to intermediate states where a random
201 // subset of the set-oops has been correctly from the clean state
202 // upon entry to the VEP of the compiled method. In the case of a
203 // machine (Intel) with a single set-oop instruction, the 32-bit
204 // immediate field must not straddle a unit of memory coherence.
205 // //%note reloc_3
206 //
207 // relocInfo::breakpoint_type -- a conditional breakpoint in the code
208 // Value: none
209 // Instruction types: any whatsoever
210 // Data: [b [T]t i...]
211 // The b is a bit-packed word representing the breakpoint's attributes.
212 // The t is a target address which the breakpoint calls (when it is enabled).
213 // The i... is a place to store one or two instruction words overwritten
214 // by a trap, so that the breakpoint may be subsequently removed.
215 //
216 // relocInfo::static_stub_type -- an extra stub for each static_call_type
217 // Value: none
218 // Instruction types: a virtual call: { set_oop; jump; }
219 // Data: [[N]n] the offset of the associated static_call reloc
220 // This stub becomes the target of a static call which must be upgraded
221 // to a virtual call (because the callee is interpreted).
222 // See [About Offsets] below.
223 // //%note reloc_2
224 //
225 // For example:
226 //
227 // INSTRUCTIONS RELOC: TYPE PREFIX DATA
228 // ------------ ---- -----------
229 // sethi %hi(myObject), R oop_type [n(myObject)]
230 // ld [R+%lo(myObject)+fldOffset], R2 oop_type [n(myObject) fldOffset]
231 // add R2, 1, R2
232 // st R2, [R+%lo(myObject)+fldOffset] oop_type [n(myObject) fldOffset]
233 //%note reloc_1
234 //
235 // This uses 4 instruction words, 8 relocation halfwords,
236 // and an entry (which is sharable) in the CodeBlob's oop pool,
237 // for a total of 36 bytes.
238 //
239 // Note that the compiler is responsible for ensuring the "fldOffset" when
240 // added to "%lo(myObject)" does not overflow the immediate fields of the
241 // memory instructions.
242 //
243 //
244 // [About Offsets] Relative offsets are supplied to this module as
245 // positive byte offsets, but they may be internally stored scaled
246 // and/or negated, depending on what is most compact for the target
247 // system. Since the object pointed to by the offset typically
248 // precedes the relocation address, it is profitable to store
249 // these negative offsets as positive numbers, but this decision
250 // is internal to the relocation information abstractions.
251 //
253 class Relocation;
254 class CodeBuffer;
255 class CodeSection;
256 class RelocIterator;
258 class relocInfo VALUE_OBJ_CLASS_SPEC {
259 friend class RelocIterator;
260 public:
261 enum relocType {
262 none = 0, // Used when no relocation should be generated
263 oop_type = 1, // embedded oop
264 virtual_call_type = 2, // a standard inline cache call for a virtual send
265 opt_virtual_call_type = 3, // a virtual call that has been statically bound (i.e., no IC cache)
266 static_call_type = 4, // a static send
267 static_stub_type = 5, // stub-entry for static send (takes care of interpreter case)
268 runtime_call_type = 6, // call to fixed external routine
269 external_word_type = 7, // reference to fixed external address
270 internal_word_type = 8, // reference within the current code blob
271 section_word_type = 9, // internal, but a cross-section reference
272 poll_type = 10, // polling instruction for safepoints
273 poll_return_type = 11, // polling instruction for safepoints at return
274 breakpoint_type = 12, // an initialization barrier or safepoint
275 metadata_type = 13, // metadata that used to be oops
276 yet_unused_type_2 = 14, // Still unused
277 data_prefix_tag = 15, // tag for a prefix (carries data arguments)
278 type_mask = 15 // A mask which selects only the above values
279 };
281 protected:
282 unsigned short _value;
284 enum RawBitsToken { RAW_BITS };
285 relocInfo(relocType type, RawBitsToken ignore, int bits)
286 : _value((type << nontype_width) + bits) { }
288 relocInfo(relocType type, RawBitsToken ignore, int off, int f)
289 : _value((type << nontype_width) + (off / (unsigned)offset_unit) + (f << offset_width)) { }
291 public:
292 // constructor
293 relocInfo(relocType type, int offset, int format = 0)
294 #ifndef ASSERT
295 {
296 (*this) = relocInfo(type, RAW_BITS, offset, format);
297 }
298 #else
299 // Put a bunch of assertions out-of-line.
300 ;
301 #endif
303 #define APPLY_TO_RELOCATIONS(visitor) \
304 visitor(oop) \
305 visitor(metadata) \
306 visitor(virtual_call) \
307 visitor(opt_virtual_call) \
308 visitor(static_call) \
309 visitor(static_stub) \
310 visitor(runtime_call) \
311 visitor(external_word) \
312 visitor(internal_word) \
313 visitor(poll) \
314 visitor(poll_return) \
315 visitor(breakpoint) \
316 visitor(section_word) \
319 public:
320 enum {
321 value_width = sizeof(unsigned short) * BitsPerByte,
322 type_width = 4, // == log2(type_mask+1)
323 nontype_width = value_width - type_width,
324 datalen_width = nontype_width-1,
325 datalen_tag = 1 << datalen_width, // or-ed into _value
326 datalen_limit = 1 << datalen_width,
327 datalen_mask = (1 << datalen_width)-1
328 };
330 // accessors
331 public:
332 relocType type() const { return (relocType)((unsigned)_value >> nontype_width); }
333 int format() const { return format_mask==0? 0: format_mask &
334 ((unsigned)_value >> offset_width); }
335 int addr_offset() const { assert(!is_prefix(), "must have offset");
336 return (_value & offset_mask)*offset_unit; }
338 protected:
339 const short* data() const { assert(is_datalen(), "must have data");
340 return (const short*)(this + 1); }
341 int datalen() const { assert(is_datalen(), "must have data");
342 return (_value & datalen_mask); }
343 int immediate() const { assert(is_immediate(), "must have immed");
344 return (_value & datalen_mask); }
345 public:
346 static int addr_unit() { return offset_unit; }
347 static int offset_limit() { return (1 << offset_width) * offset_unit; }
349 void set_type(relocType type);
350 void set_format(int format);
352 void remove() { set_type(none); }
354 protected:
355 bool is_none() const { return type() == none; }
356 bool is_prefix() const { return type() == data_prefix_tag; }
357 bool is_datalen() const { assert(is_prefix(), "must be prefix");
358 return (_value & datalen_tag) != 0; }
359 bool is_immediate() const { assert(is_prefix(), "must be prefix");
360 return (_value & datalen_tag) == 0; }
362 public:
363 // Occasionally records of type relocInfo::none will appear in the stream.
364 // We do not bother to filter these out, but clients should ignore them.
365 // These records serve as "filler" in three ways:
366 // - to skip large spans of unrelocated code (this is rare)
367 // - to pad out the relocInfo array to the required oop alignment
368 // - to disable old relocation information which is no longer applicable
370 inline friend relocInfo filler_relocInfo();
372 // Every non-prefix relocation may be preceded by at most one prefix,
373 // which supplies 1 or more halfwords of associated data. Conventionally,
374 // an int is represented by 0, 1, or 2 halfwords, depending on how
375 // many bits are required to represent the value. (In addition,
376 // if the sole halfword is a 10-bit unsigned number, it is made
377 // "immediate" in the prefix header word itself. This optimization
378 // is invisible outside this module.)
380 inline friend relocInfo prefix_relocInfo(int datalen = 0);
382 protected:
383 // an immediate relocInfo optimizes a prefix with one 10-bit unsigned value
384 static relocInfo immediate_relocInfo(int data0) {
385 assert(fits_into_immediate(data0), "data0 in limits");
386 return relocInfo(relocInfo::data_prefix_tag, RAW_BITS, data0);
387 }
388 static bool fits_into_immediate(int data0) {
389 return (data0 >= 0 && data0 < datalen_limit);
390 }
392 public:
393 // Support routines for compilers.
395 // This routine takes an infant relocInfo (unprefixed) and
396 // edits in its prefix, if any. It also updates dest.locs_end.
397 void initialize(CodeSection* dest, Relocation* reloc);
399 // This routine updates a prefix and returns the limit pointer.
400 // It tries to compress the prefix from 32 to 16 bits, and if
401 // successful returns a reduced "prefix_limit" pointer.
402 relocInfo* finish_prefix(short* prefix_limit);
404 // bit-packers for the data array:
406 // As it happens, the bytes within the shorts are ordered natively,
407 // but the shorts within the word are ordered big-endian.
408 // This is an arbitrary choice, made this way mainly to ease debugging.
409 static int data0_from_int(jint x) { return x >> value_width; }
410 static int data1_from_int(jint x) { return (short)x; }
411 static jint jint_from_data(short* data) {
412 return (data[0] << value_width) + (unsigned short)data[1];
413 }
415 static jint short_data_at(int n, short* data, int datalen) {
416 return datalen > n ? data[n] : 0;
417 }
419 static jint jint_data_at(int n, short* data, int datalen) {
420 return datalen > n+1 ? jint_from_data(&data[n]) : short_data_at(n, data, datalen);
421 }
423 // Update methods for relocation information
424 // (since code is dynamically patched, we also need to dynamically update the relocation info)
425 // Both methods takes old_type, so it is able to performe sanity checks on the information removed.
426 static void change_reloc_info_for_address(RelocIterator *itr, address pc, relocType old_type, relocType new_type);
427 static void remove_reloc_info_for_address(RelocIterator *itr, address pc, relocType old_type);
429 // Machine dependent stuff
430 #ifdef TARGET_ARCH_x86
431 # include "relocInfo_x86.hpp"
432 #endif
433 #ifdef TARGET_ARCH_sparc
434 # include "relocInfo_sparc.hpp"
435 #endif
436 #ifdef TARGET_ARCH_zero
437 # include "relocInfo_zero.hpp"
438 #endif
439 #ifdef TARGET_ARCH_arm
440 # include "relocInfo_arm.hpp"
441 #endif
442 #ifdef TARGET_ARCH_ppc
443 # include "relocInfo_ppc.hpp"
444 #endif
447 protected:
448 // Derived constant, based on format_width which is PD:
449 enum {
450 offset_width = nontype_width - format_width,
451 offset_mask = (1<<offset_width) - 1,
452 format_mask = (1<<format_width) - 1
453 };
454 public:
455 enum {
456 // Conservatively large estimate of maximum length (in shorts)
457 // of any relocation record (probably breakpoints are largest).
458 // Extended format is length prefix, data words, and tag/offset suffix.
459 length_limit = 1 + 1 + (3*BytesPerWord/BytesPerShort) + 1,
460 have_format = format_width > 0
461 };
462 };
464 #define FORWARD_DECLARE_EACH_CLASS(name) \
465 class name##_Relocation;
466 APPLY_TO_RELOCATIONS(FORWARD_DECLARE_EACH_CLASS)
467 #undef FORWARD_DECLARE_EACH_CLASS
471 inline relocInfo filler_relocInfo() {
472 return relocInfo(relocInfo::none, relocInfo::offset_limit() - relocInfo::offset_unit);
473 }
475 inline relocInfo prefix_relocInfo(int datalen) {
476 assert(relocInfo::fits_into_immediate(datalen), "datalen in limits");
477 return relocInfo(relocInfo::data_prefix_tag, relocInfo::RAW_BITS, relocInfo::datalen_tag | datalen);
478 }
481 // Holder for flyweight relocation objects.
482 // Although the flyweight subclasses are of varying sizes,
483 // the holder is "one size fits all".
484 class RelocationHolder VALUE_OBJ_CLASS_SPEC {
485 friend class Relocation;
486 friend class CodeSection;
488 private:
489 // this preallocated memory must accommodate all subclasses of Relocation
490 // (this number is assertion-checked in Relocation::operator new)
491 enum { _relocbuf_size = 5 };
492 void* _relocbuf[ _relocbuf_size ];
494 public:
495 Relocation* reloc() const { return (Relocation*) &_relocbuf[0]; }
496 inline relocInfo::relocType type() const;
498 // Add a constant offset to a relocation. Helper for class Address.
499 RelocationHolder plus(int offset) const;
501 inline RelocationHolder(); // initializes type to none
503 inline RelocationHolder(Relocation* r); // make a copy
505 static const RelocationHolder none;
506 };
508 // A RelocIterator iterates through the relocation information of a CodeBlob.
509 // It is a variable BoundRelocation which is able to take on successive
510 // values as it is advanced through a code stream.
511 // Usage:
512 // RelocIterator iter(nm);
513 // while (iter.next()) {
514 // iter.reloc()->some_operation();
515 // }
516 // or:
517 // RelocIterator iter(nm);
518 // while (iter.next()) {
519 // switch (iter.type()) {
520 // case relocInfo::oop_type :
521 // case relocInfo::ic_type :
522 // case relocInfo::prim_type :
523 // case relocInfo::uncommon_type :
524 // case relocInfo::runtime_call_type :
525 // case relocInfo::internal_word_type:
526 // case relocInfo::external_word_type:
527 // ...
528 // }
529 // }
531 class RelocIterator : public StackObj {
532 enum { SECT_LIMIT = 3 }; // must be equal to CodeBuffer::SECT_LIMIT, checked in ctor
533 friend class Relocation;
534 friend class relocInfo; // for change_reloc_info_for_address only
535 typedef relocInfo::relocType relocType;
537 private:
538 address _limit; // stop producing relocations after this _addr
539 relocInfo* _current; // the current relocation information
540 relocInfo* _end; // end marker; we're done iterating when _current == _end
541 nmethod* _code; // compiled method containing _addr
542 address _addr; // instruction to which the relocation applies
543 short _databuf; // spare buffer for compressed data
544 short* _data; // pointer to the relocation's data
545 short _datalen; // number of halfwords in _data
546 char _format; // position within the instruction
548 // Base addresses needed to compute targets of section_word_type relocs.
549 address _section_start[SECT_LIMIT];
550 address _section_end [SECT_LIMIT];
552 void set_has_current(bool b) {
553 _datalen = !b ? -1 : 0;
554 debug_only(_data = NULL);
555 }
556 void set_current(relocInfo& ri) {
557 _current = &ri;
558 set_has_current(true);
559 }
561 RelocationHolder _rh; // where the current relocation is allocated
563 relocInfo* current() const { assert(has_current(), "must have current");
564 return _current; }
566 void set_limits(address begin, address limit);
568 void advance_over_prefix(); // helper method
570 void initialize_misc();
572 void initialize(nmethod* nm, address begin, address limit);
574 friend class PatchingRelocIterator;
575 // make an uninitialized one, for PatchingRelocIterator:
576 RelocIterator() { initialize_misc(); }
578 public:
579 // constructor
580 RelocIterator(nmethod* nm, address begin = NULL, address limit = NULL);
581 RelocIterator(CodeSection* cb, address begin = NULL, address limit = NULL);
583 // get next reloc info, return !eos
584 bool next() {
585 _current++;
586 assert(_current <= _end, "must not overrun relocInfo");
587 if (_current == _end) {
588 set_has_current(false);
589 return false;
590 }
591 set_has_current(true);
593 if (_current->is_prefix()) {
594 advance_over_prefix();
595 assert(!current()->is_prefix(), "only one prefix at a time");
596 }
598 _addr += _current->addr_offset();
600 if (_limit != NULL && _addr >= _limit) {
601 set_has_current(false);
602 return false;
603 }
605 if (relocInfo::have_format) _format = current()->format();
606 return true;
607 }
609 // accessors
610 address limit() const { return _limit; }
611 void set_limit(address x);
612 relocType type() const { return current()->type(); }
613 int format() const { return (relocInfo::have_format) ? current()->format() : 0; }
614 address addr() const { return _addr; }
615 nmethod* code() const { return _code; }
616 short* data() const { return _data; }
617 int datalen() const { return _datalen; }
618 bool has_current() const { return _datalen >= 0; }
620 void set_addr(address addr) { _addr = addr; }
621 bool addr_in_const() const;
623 address section_start(int n) const {
624 assert(_section_start[n], "must be initialized");
625 return _section_start[n];
626 }
627 address section_end(int n) const {
628 assert(_section_end[n], "must be initialized");
629 return _section_end[n];
630 }
632 // The address points to the affected displacement part of the instruction.
633 // For RISC, this is just the whole instruction.
634 // For Intel, this is an unaligned 32-bit word.
636 // type-specific relocation accessors: oop_Relocation* oop_reloc(), etc.
637 #define EACH_TYPE(name) \
638 inline name##_Relocation* name##_reloc();
639 APPLY_TO_RELOCATIONS(EACH_TYPE)
640 #undef EACH_TYPE
641 // generic relocation accessor; switches on type to call the above
642 Relocation* reloc();
644 // CodeBlob's have relocation indexes for faster random access:
645 static int locs_and_index_size(int code_size, int locs_size);
646 // Store an index into [dest_start+dest_count..dest_end).
647 // At dest_start[0..dest_count] is the actual relocation information.
648 // Everything else up to dest_end is free space for the index.
649 static void create_index(relocInfo* dest_begin, int dest_count, relocInfo* dest_end);
651 #ifndef PRODUCT
652 public:
653 void print();
654 void print_current();
655 #endif
656 };
659 // A Relocation is a flyweight object allocated within a RelocationHolder.
660 // It represents the relocation data of relocation record.
661 // So, the RelocIterator unpacks relocInfos into Relocations.
663 class Relocation VALUE_OBJ_CLASS_SPEC {
664 friend class RelocationHolder;
665 friend class RelocIterator;
667 private:
668 static void guarantee_size();
670 // When a relocation has been created by a RelocIterator,
671 // this field is non-null. It allows the relocation to know
672 // its context, such as the address to which it applies.
673 RelocIterator* _binding;
675 protected:
676 RelocIterator* binding() const {
677 assert(_binding != NULL, "must be bound");
678 return _binding;
679 }
680 void set_binding(RelocIterator* b) {
681 assert(_binding == NULL, "must be unbound");
682 _binding = b;
683 assert(_binding != NULL, "must now be bound");
684 }
686 Relocation() {
687 _binding = NULL;
688 }
690 static RelocationHolder newHolder() {
691 return RelocationHolder();
692 }
694 public:
695 void* operator new(size_t size, const RelocationHolder& holder) {
696 if (size > sizeof(holder._relocbuf)) guarantee_size();
697 assert((void* const *)holder.reloc() == &holder._relocbuf[0], "ptrs must agree");
698 return holder.reloc();
699 }
701 // make a generic relocation for a given type (if possible)
702 static RelocationHolder spec_simple(relocInfo::relocType rtype);
704 // here is the type-specific hook which writes relocation data:
705 virtual void pack_data_to(CodeSection* dest) { }
707 // here is the type-specific hook which reads (unpacks) relocation data:
708 virtual void unpack_data() {
709 assert(datalen()==0 || type()==relocInfo::none, "no data here");
710 }
712 static bool is_reloc_index(intptr_t index) {
713 return 0 < index && index < os::vm_page_size();
714 }
716 protected:
717 // Helper functions for pack_data_to() and unpack_data().
719 // Most of the compression logic is confined here.
720 // (The "immediate data" mechanism of relocInfo works independently
721 // of this stuff, and acts to further compress most 1-word data prefixes.)
723 // A variable-width int is encoded as a short if it will fit in 16 bits.
724 // The decoder looks at datalen to decide whether to unpack short or jint.
725 // Most relocation records are quite simple, containing at most two ints.
727 static bool is_short(jint x) { return x == (short)x; }
728 static short* add_short(short* p, int x) { *p++ = x; return p; }
729 static short* add_jint (short* p, jint x) {
730 *p++ = relocInfo::data0_from_int(x); *p++ = relocInfo::data1_from_int(x);
731 return p;
732 }
733 static short* add_var_int(short* p, jint x) { // add a variable-width int
734 if (is_short(x)) p = add_short(p, x);
735 else p = add_jint (p, x);
736 return p;
737 }
739 static short* pack_1_int_to(short* p, jint x0) {
740 // Format is one of: [] [x] [Xx]
741 if (x0 != 0) p = add_var_int(p, x0);
742 return p;
743 }
744 int unpack_1_int() {
745 assert(datalen() <= 2, "too much data");
746 return relocInfo::jint_data_at(0, data(), datalen());
747 }
749 // With two ints, the short form is used only if both ints are short.
750 short* pack_2_ints_to(short* p, jint x0, jint x1) {
751 // Format is one of: [] [x y?] [Xx Y?y]
752 if (x0 == 0 && x1 == 0) {
753 // no halfwords needed to store zeroes
754 } else if (is_short(x0) && is_short(x1)) {
755 // 1-2 halfwords needed to store shorts
756 p = add_short(p, x0); if (x1!=0) p = add_short(p, x1);
757 } else {
758 // 3-4 halfwords needed to store jints
759 p = add_jint(p, x0); p = add_var_int(p, x1);
760 }
761 return p;
762 }
763 void unpack_2_ints(jint& x0, jint& x1) {
764 int dlen = datalen();
765 short* dp = data();
766 if (dlen <= 2) {
767 x0 = relocInfo::short_data_at(0, dp, dlen);
768 x1 = relocInfo::short_data_at(1, dp, dlen);
769 } else {
770 assert(dlen <= 4, "too much data");
771 x0 = relocInfo::jint_data_at(0, dp, dlen);
772 x1 = relocInfo::jint_data_at(2, dp, dlen);
773 }
774 }
776 protected:
777 // platform-dependent utilities for decoding and patching instructions
778 void pd_set_data_value (address x, intptr_t off, bool verify_only = false); // a set or mem-ref
779 void pd_verify_data_value (address x, intptr_t off) { pd_set_data_value(x, off, true); }
780 address pd_call_destination (address orig_addr = NULL);
781 void pd_set_call_destination (address x);
782 void pd_swap_in_breakpoint (address x, short* instrs, int instrlen);
783 void pd_swap_out_breakpoint (address x, short* instrs, int instrlen);
784 static int pd_breakpoint_size ();
786 // this extracts the address of an address in the code stream instead of the reloc data
787 address* pd_address_in_code ();
789 // this extracts an address from the code stream instead of the reloc data
790 address pd_get_address_from_code ();
792 // these convert from byte offsets, to scaled offsets, to addresses
793 static jint scaled_offset(address x, address base) {
794 int byte_offset = x - base;
795 int offset = -byte_offset / relocInfo::addr_unit();
796 assert(address_from_scaled_offset(offset, base) == x, "just checkin'");
797 return offset;
798 }
799 static jint scaled_offset_null_special(address x, address base) {
800 // Some relocations treat offset=0 as meaning NULL.
801 // Handle this extra convention carefully.
802 if (x == NULL) return 0;
803 assert(x != base, "offset must not be zero");
804 return scaled_offset(x, base);
805 }
806 static address address_from_scaled_offset(jint offset, address base) {
807 int byte_offset = -( offset * relocInfo::addr_unit() );
808 return base + byte_offset;
809 }
811 // these convert between indexes and addresses in the runtime system
812 static int32_t runtime_address_to_index(address runtime_address);
813 static address index_to_runtime_address(int32_t index);
815 // helpers for mapping between old and new addresses after a move or resize
816 address old_addr_for(address newa, const CodeBuffer* src, CodeBuffer* dest);
817 address new_addr_for(address olda, const CodeBuffer* src, CodeBuffer* dest);
818 void normalize_address(address& addr, const CodeSection* dest, bool allow_other_sections = false);
820 public:
821 // accessors which only make sense for a bound Relocation
822 address addr() const { return binding()->addr(); }
823 nmethod* code() const { return binding()->code(); }
824 bool addr_in_const() const { return binding()->addr_in_const(); }
825 protected:
826 short* data() const { return binding()->data(); }
827 int datalen() const { return binding()->datalen(); }
828 int format() const { return binding()->format(); }
830 public:
831 virtual relocInfo::relocType type() { return relocInfo::none; }
833 // is it a call instruction?
834 virtual bool is_call() { return false; }
836 // is it a data movement instruction?
837 virtual bool is_data() { return false; }
839 // some relocations can compute their own values
840 virtual address value();
842 // all relocations are able to reassert their values
843 virtual void set_value(address x);
845 virtual void clear_inline_cache() { }
847 // This method assumes that all virtual/static (inline) caches are cleared (since for static_call_type and
848 // ic_call_type is not always posisition dependent (depending on the state of the cache)). However, this is
849 // probably a reasonable assumption, since empty caches simplifies code reloacation.
850 virtual void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest) { }
852 void print();
853 };
856 // certain inlines must be deferred until class Relocation is defined:
858 inline RelocationHolder::RelocationHolder() {
859 // initialize the vtbl, just to keep things type-safe
860 new(*this) Relocation();
861 }
864 inline RelocationHolder::RelocationHolder(Relocation* r) {
865 // wordwise copy from r (ok if it copies garbage after r)
866 for (int i = 0; i < _relocbuf_size; i++) {
867 _relocbuf[i] = ((void**)r)[i];
868 }
869 }
872 relocInfo::relocType RelocationHolder::type() const {
873 return reloc()->type();
874 }
876 // A DataRelocation always points at a memory or load-constant instruction..
877 // It is absolute on most machines, and the constant is split on RISCs.
878 // The specific subtypes are oop, external_word, and internal_word.
879 // By convention, the "value" does not include a separately reckoned "offset".
880 class DataRelocation : public Relocation {
881 public:
882 bool is_data() { return true; }
884 // both target and offset must be computed somehow from relocation data
885 virtual int offset() { return 0; }
886 address value() = 0;
887 void set_value(address x) { set_value(x, offset()); }
888 void set_value(address x, intptr_t o) {
889 if (addr_in_const())
890 *(address*)addr() = x;
891 else
892 pd_set_data_value(x, o);
893 }
894 void verify_value(address x) {
895 if (addr_in_const())
896 assert(*(address*)addr() == x, "must agree");
897 else
898 pd_verify_data_value(x, offset());
899 }
901 // The "o" (displacement) argument is relevant only to split relocations
902 // on RISC machines. In some CPUs (SPARC), the set-hi and set-lo ins'ns
903 // can encode more than 32 bits between them. This allows compilers to
904 // share set-hi instructions between addresses that differ by a small
905 // offset (e.g., different static variables in the same class).
906 // On such machines, the "x" argument to set_value on all set-lo
907 // instructions must be the same as the "x" argument for the
908 // corresponding set-hi instructions. The "o" arguments for the
909 // set-hi instructions are ignored, and must not affect the high-half
910 // immediate constant. The "o" arguments for the set-lo instructions are
911 // added into the low-half immediate constant, and must not overflow it.
912 };
914 // A CallRelocation always points at a call instruction.
915 // It is PC-relative on most machines.
916 class CallRelocation : public Relocation {
917 public:
918 bool is_call() { return true; }
920 address destination() { return pd_call_destination(); }
921 void set_destination(address x); // pd_set_call_destination
923 void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest);
924 address value() { return destination(); }
925 void set_value(address x) { set_destination(x); }
926 };
928 class oop_Relocation : public DataRelocation {
929 relocInfo::relocType type() { return relocInfo::oop_type; }
931 public:
932 // encode in one of these formats: [] [n] [n l] [Nn l] [Nn Ll]
933 // an oop in the CodeBlob's oop pool
934 static RelocationHolder spec(int oop_index, int offset = 0) {
935 assert(oop_index > 0, "must be a pool-resident oop");
936 RelocationHolder rh = newHolder();
937 new(rh) oop_Relocation(oop_index, offset);
938 return rh;
939 }
940 // an oop in the instruction stream
941 static RelocationHolder spec_for_immediate() {
942 const int oop_index = 0;
943 const int offset = 0; // if you want an offset, use the oop pool
944 RelocationHolder rh = newHolder();
945 new(rh) oop_Relocation(oop_index, offset);
946 return rh;
947 }
949 private:
950 jint _oop_index; // if > 0, index into CodeBlob::oop_at
951 jint _offset; // byte offset to apply to the oop itself
953 oop_Relocation(int oop_index, int offset) {
954 _oop_index = oop_index; _offset = offset;
955 }
957 friend class RelocIterator;
958 oop_Relocation() { }
960 public:
961 int oop_index() { return _oop_index; }
962 int offset() { return _offset; }
964 // data is packed in "2_ints" format: [i o] or [Ii Oo]
965 void pack_data_to(CodeSection* dest);
966 void unpack_data();
968 void fix_oop_relocation(); // reasserts oop value
970 void verify_oop_relocation();
972 address value() { return (address) *oop_addr(); }
974 bool oop_is_immediate() { return oop_index() == 0; }
976 oop* oop_addr(); // addr or &pool[jint_data]
977 oop oop_value(); // *oop_addr
978 // Note: oop_value transparently converts Universe::non_oop_word to NULL.
979 };
982 // copy of oop_Relocation for now but may delete stuff in both/either
983 class metadata_Relocation : public DataRelocation {
984 relocInfo::relocType type() { return relocInfo::metadata_type; }
986 public:
987 // encode in one of these formats: [] [n] [n l] [Nn l] [Nn Ll]
988 // an metadata in the CodeBlob's metadata pool
989 static RelocationHolder spec(int metadata_index, int offset = 0) {
990 assert(metadata_index > 0, "must be a pool-resident metadata");
991 RelocationHolder rh = newHolder();
992 new(rh) metadata_Relocation(metadata_index, offset);
993 return rh;
994 }
995 // an metadata in the instruction stream
996 static RelocationHolder spec_for_immediate() {
997 const int metadata_index = 0;
998 const int offset = 0; // if you want an offset, use the metadata pool
999 RelocationHolder rh = newHolder();
1000 new(rh) metadata_Relocation(metadata_index, offset);
1001 return rh;
1002 }
1004 private:
1005 jint _metadata_index; // if > 0, index into nmethod::metadata_at
1006 jint _offset; // byte offset to apply to the metadata itself
1008 metadata_Relocation(int metadata_index, int offset) {
1009 _metadata_index = metadata_index; _offset = offset;
1010 }
1012 friend class RelocIterator;
1013 metadata_Relocation() { }
1015 // Fixes a Metadata pointer in the code. Most platforms embeds the
1016 // Metadata pointer in the code at compile time so this is empty
1017 // for them.
1018 void pd_fix_value(address x);
1020 public:
1021 int metadata_index() { return _metadata_index; }
1022 int offset() { return _offset; }
1024 // data is packed in "2_ints" format: [i o] or [Ii Oo]
1025 void pack_data_to(CodeSection* dest);
1026 void unpack_data();
1028 void fix_metadata_relocation(); // reasserts metadata value
1030 void verify_metadata_relocation();
1032 address value() { return (address) *metadata_addr(); }
1034 bool metadata_is_immediate() { return metadata_index() == 0; }
1036 Metadata** metadata_addr(); // addr or &pool[jint_data]
1037 Metadata* metadata_value(); // *metadata_addr
1038 // Note: metadata_value transparently converts Universe::non_metadata_word to NULL.
1039 };
1042 class virtual_call_Relocation : public CallRelocation {
1043 relocInfo::relocType type() { return relocInfo::virtual_call_type; }
1045 public:
1046 // "cached_value" points to the first associated set-oop.
1047 // The oop_limit helps find the last associated set-oop.
1048 // (See comments at the top of this file.)
1049 static RelocationHolder spec(address cached_value) {
1050 RelocationHolder rh = newHolder();
1051 new(rh) virtual_call_Relocation(cached_value);
1052 return rh;
1053 }
1055 virtual_call_Relocation(address cached_value) {
1056 _cached_value = cached_value;
1057 assert(cached_value != NULL, "first oop address must be specified");
1058 }
1060 private:
1061 address _cached_value; // location of set-value instruction
1063 friend class RelocIterator;
1064 virtual_call_Relocation() { }
1067 public:
1068 address cached_value();
1070 // data is packed as scaled offsets in "2_ints" format: [f l] or [Ff Ll]
1071 // oop_limit is set to 0 if the limit falls somewhere within the call.
1072 // When unpacking, a zero oop_limit is taken to refer to the end of the call.
1073 // (This has the effect of bringing in the call's delay slot on SPARC.)
1074 void pack_data_to(CodeSection* dest);
1075 void unpack_data();
1077 void clear_inline_cache();
1078 };
1081 class opt_virtual_call_Relocation : public CallRelocation {
1082 relocInfo::relocType type() { return relocInfo::opt_virtual_call_type; }
1084 public:
1085 static RelocationHolder spec() {
1086 RelocationHolder rh = newHolder();
1087 new(rh) opt_virtual_call_Relocation();
1088 return rh;
1089 }
1091 private:
1092 friend class RelocIterator;
1093 opt_virtual_call_Relocation() { }
1095 public:
1096 void clear_inline_cache();
1098 // find the matching static_stub
1099 address static_stub();
1100 };
1103 class static_call_Relocation : public CallRelocation {
1104 relocInfo::relocType type() { return relocInfo::static_call_type; }
1106 public:
1107 static RelocationHolder spec() {
1108 RelocationHolder rh = newHolder();
1109 new(rh) static_call_Relocation();
1110 return rh;
1111 }
1113 private:
1114 friend class RelocIterator;
1115 static_call_Relocation() { }
1117 public:
1118 void clear_inline_cache();
1120 // find the matching static_stub
1121 address static_stub();
1122 };
1124 class static_stub_Relocation : public Relocation {
1125 relocInfo::relocType type() { return relocInfo::static_stub_type; }
1127 public:
1128 static RelocationHolder spec(address static_call) {
1129 RelocationHolder rh = newHolder();
1130 new(rh) static_stub_Relocation(static_call);
1131 return rh;
1132 }
1134 private:
1135 address _static_call; // location of corresponding static_call
1137 static_stub_Relocation(address static_call) {
1138 _static_call = static_call;
1139 }
1141 friend class RelocIterator;
1142 static_stub_Relocation() { }
1144 public:
1145 void clear_inline_cache();
1147 address static_call() { return _static_call; }
1149 // data is packed as a scaled offset in "1_int" format: [c] or [Cc]
1150 void pack_data_to(CodeSection* dest);
1151 void unpack_data();
1152 };
1154 class runtime_call_Relocation : public CallRelocation {
1155 relocInfo::relocType type() { return relocInfo::runtime_call_type; }
1157 public:
1158 static RelocationHolder spec() {
1159 RelocationHolder rh = newHolder();
1160 new(rh) runtime_call_Relocation();
1161 return rh;
1162 }
1164 private:
1165 friend class RelocIterator;
1166 runtime_call_Relocation() { }
1168 public:
1169 };
1171 class external_word_Relocation : public DataRelocation {
1172 relocInfo::relocType type() { return relocInfo::external_word_type; }
1174 public:
1175 static RelocationHolder spec(address target) {
1176 assert(target != NULL, "must not be null");
1177 RelocationHolder rh = newHolder();
1178 new(rh) external_word_Relocation(target);
1179 return rh;
1180 }
1182 // Use this one where all 32/64 bits of the target live in the code stream.
1183 // The target must be an intptr_t, and must be absolute (not relative).
1184 static RelocationHolder spec_for_immediate() {
1185 RelocationHolder rh = newHolder();
1186 new(rh) external_word_Relocation(NULL);
1187 return rh;
1188 }
1190 // Some address looking values aren't safe to treat as relocations
1191 // and should just be treated as constants.
1192 static bool can_be_relocated(address target) {
1193 return target != NULL && !is_reloc_index((intptr_t)target);
1194 }
1196 private:
1197 address _target; // address in runtime
1199 external_word_Relocation(address target) {
1200 _target = target;
1201 }
1203 friend class RelocIterator;
1204 external_word_Relocation() { }
1206 public:
1207 // data is packed as a well-known address in "1_int" format: [a] or [Aa]
1208 // The function runtime_address_to_index is used to turn full addresses
1209 // to short indexes, if they are pre-registered by the stub mechanism.
1210 // If the "a" value is 0 (i.e., _target is NULL), the address is stored
1211 // in the code stream. See external_word_Relocation::target().
1212 void pack_data_to(CodeSection* dest);
1213 void unpack_data();
1215 void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest);
1216 address target(); // if _target==NULL, fetch addr from code stream
1217 address value() { return target(); }
1218 };
1220 class internal_word_Relocation : public DataRelocation {
1221 relocInfo::relocType type() { return relocInfo::internal_word_type; }
1223 public:
1224 static RelocationHolder spec(address target) {
1225 assert(target != NULL, "must not be null");
1226 RelocationHolder rh = newHolder();
1227 new(rh) internal_word_Relocation(target);
1228 return rh;
1229 }
1231 // use this one where all the bits of the target can fit in the code stream:
1232 static RelocationHolder spec_for_immediate() {
1233 RelocationHolder rh = newHolder();
1234 new(rh) internal_word_Relocation(NULL);
1235 return rh;
1236 }
1238 internal_word_Relocation(address target) {
1239 _target = target;
1240 _section = -1; // self-relative
1241 }
1243 protected:
1244 address _target; // address in CodeBlob
1245 int _section; // section providing base address, if any
1247 friend class RelocIterator;
1248 internal_word_Relocation() { }
1250 // bit-width of LSB field in packed offset, if section >= 0
1251 enum { section_width = 2 }; // must equal CodeBuffer::sect_bits
1253 public:
1254 // data is packed as a scaled offset in "1_int" format: [o] or [Oo]
1255 // If the "o" value is 0 (i.e., _target is NULL), the offset is stored
1256 // in the code stream. See internal_word_Relocation::target().
1257 // If _section is not -1, it is appended to the low bits of the offset.
1258 void pack_data_to(CodeSection* dest);
1259 void unpack_data();
1261 void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest);
1262 address target(); // if _target==NULL, fetch addr from code stream
1263 int section() { return _section; }
1264 address value() { return target(); }
1265 };
1267 class section_word_Relocation : public internal_word_Relocation {
1268 relocInfo::relocType type() { return relocInfo::section_word_type; }
1270 public:
1271 static RelocationHolder spec(address target, int section) {
1272 RelocationHolder rh = newHolder();
1273 new(rh) section_word_Relocation(target, section);
1274 return rh;
1275 }
1277 section_word_Relocation(address target, int section) {
1278 assert(target != NULL, "must not be null");
1279 assert(section >= 0, "must be a valid section");
1280 _target = target;
1281 _section = section;
1282 }
1284 //void pack_data_to -- inherited
1285 void unpack_data();
1287 private:
1288 friend class RelocIterator;
1289 section_word_Relocation() { }
1290 };
1293 class poll_Relocation : public Relocation {
1294 bool is_data() { return true; }
1295 relocInfo::relocType type() { return relocInfo::poll_type; }
1296 void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest);
1297 };
1299 class poll_return_Relocation : public Relocation {
1300 bool is_data() { return true; }
1301 relocInfo::relocType type() { return relocInfo::poll_return_type; }
1302 void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest);
1303 };
1306 class breakpoint_Relocation : public Relocation {
1307 relocInfo::relocType type() { return relocInfo::breakpoint_type; }
1309 enum {
1310 // attributes which affect the interpretation of the data:
1311 removable_attr = 0x0010, // buffer [i...] allows for undoing the trap
1312 internal_attr = 0x0020, // the target is an internal addr (local stub)
1313 settable_attr = 0x0040, // the target is settable
1315 // states which can change over time:
1316 enabled_state = 0x0100, // breakpoint must be active in running code
1317 active_state = 0x0200, // breakpoint instruction actually in code
1319 kind_mask = 0x000F, // mask for extracting kind
1320 high_bit = 0x4000 // extra bit which is always set
1321 };
1323 public:
1324 enum {
1325 // kinds:
1326 initialization = 1,
1327 safepoint = 2
1328 };
1330 // If target is NULL, 32 bits are reserved for a later set_target().
1331 static RelocationHolder spec(int kind, address target = NULL, bool internal_target = false) {
1332 RelocationHolder rh = newHolder();
1333 new(rh) breakpoint_Relocation(kind, target, internal_target);
1334 return rh;
1335 }
1337 private:
1338 // We require every bits value to NOT to fit into relocInfo::datalen_width,
1339 // because we are going to actually store state in the reloc, and so
1340 // cannot allow it to be compressed (and hence copied by the iterator).
1342 short _bits; // bit-encoded kind, attrs, & state
1343 address _target;
1345 breakpoint_Relocation(int kind, address target, bool internal_target);
1347 friend class RelocIterator;
1348 breakpoint_Relocation() { }
1350 short bits() const { return _bits; }
1351 short& live_bits() const { return data()[0]; }
1352 short* instrs() const { return data() + datalen() - instrlen(); }
1353 int instrlen() const { return removable() ? pd_breakpoint_size() : 0; }
1355 void set_bits(short x) {
1356 assert(live_bits() == _bits, "must be the only mutator of reloc info");
1357 live_bits() = _bits = x;
1358 }
1360 public:
1361 address target() const;
1362 void set_target(address x);
1364 int kind() const { return bits() & kind_mask; }
1365 bool enabled() const { return (bits() & enabled_state) != 0; }
1366 bool active() const { return (bits() & active_state) != 0; }
1367 bool internal() const { return (bits() & internal_attr) != 0; }
1368 bool removable() const { return (bits() & removable_attr) != 0; }
1369 bool settable() const { return (bits() & settable_attr) != 0; }
1371 void set_enabled(bool b); // to activate, you must also say set_active
1372 void set_active(bool b); // actually inserts bpt (must be enabled 1st)
1374 // data is packed as 16 bits, followed by the target (1 or 2 words), followed
1375 // if necessary by empty storage for saving away original instruction bytes.
1376 void pack_data_to(CodeSection* dest);
1377 void unpack_data();
1379 // during certain operations, breakpoints must be out of the way:
1380 void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest) {
1381 assert(!active(), "cannot perform relocation on enabled breakpoints");
1382 }
1383 };
1386 // We know all the xxx_Relocation classes, so now we can define these:
1387 #define EACH_CASE(name) \
1388 inline name##_Relocation* RelocIterator::name##_reloc() { \
1389 assert(type() == relocInfo::name##_type, "type must agree"); \
1390 /* The purpose of the placed "new" is to re-use the same */ \
1391 /* stack storage for each new iteration. */ \
1392 name##_Relocation* r = new(_rh) name##_Relocation(); \
1393 r->set_binding(this); \
1394 r->name##_Relocation::unpack_data(); \
1395 return r; \
1396 }
1397 APPLY_TO_RELOCATIONS(EACH_CASE);
1398 #undef EACH_CASE
1400 inline RelocIterator::RelocIterator(nmethod* nm, address begin, address limit) {
1401 initialize(nm, begin, limit);
1402 }
1404 // if you are going to patch code, you should use this subclass of
1405 // RelocIterator
1406 class PatchingRelocIterator : public RelocIterator {
1407 private:
1408 RelocIterator _init_state;
1410 void prepass(); // deactivates all breakpoints
1411 void postpass(); // reactivates all enabled breakpoints
1413 // do not copy these puppies; it would have unpredictable side effects
1414 // these are private and have no bodies defined because they should not be called
1415 PatchingRelocIterator(const RelocIterator&);
1416 void operator=(const RelocIterator&);
1418 public:
1419 PatchingRelocIterator(nmethod* nm, address begin = NULL, address limit = NULL)
1420 : RelocIterator(nm, begin, limit) { prepass(); }
1422 ~PatchingRelocIterator() { postpass(); }
1423 };
1425 #endif // SHARE_VM_CODE_RELOCINFO_HPP