1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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24
25 #ifndef SHARE_CODE_RELOCINFO_HPP
26 #define SHARE_CODE_RELOCINFO_HPP
27
28 #include "memory/allocation.hpp"
29 #include "oops/oopsHierarchy.hpp"
30 #include "runtime/osInfo.hpp"
31 #include "utilities/checkedCast.hpp"
32 #include "utilities/globalDefinitions.hpp"
33 #include "utilities/macros.hpp"
34
35 #include <new>
36
37 class CodeBlob;
38 class Metadata;
39 class NativeMovConstReg;
40 class nmethod;
41
42 // Types in this file:
43 // relocInfo
44 // One element of an array of halfwords encoding compressed relocations.
45 // Also, the source of relocation types (relocInfo::oop_type, ...).
46 // Relocation
47 // A flyweight object representing a single relocation.
48 // It is fully unpacked from the compressed relocation array.
49 // metadata_Relocation, ... (subclasses of Relocation)
50 // The location of some type-specific operations (metadata_addr, ...).
51 // Also, the source of relocation specs (metadata_Relocation::spec, ...).
52 // oop_Relocation, ... (subclasses of Relocation)
53 // oops in the code stream (strings, class loaders)
54 // Also, the source of relocation specs (oop_Relocation::spec, ...).
55 // RelocationHolder
56 // A value type which acts as a union holding a Relocation object.
57 // Represents a relocation spec passed into a CodeBuffer during assembly.
58 // RelocIterator
59 // A StackObj which iterates over the relocations associated with
60 // a range of code addresses. Can be used to operate a copy of code.
61
62
63 // Notes on relocType:
64 //
65 // These hold enough information to read or write a value embedded in
66 // the instructions of an CodeBlob. They're used to update:
67 //
68 // 1) embedded oops (isOop() == true)
69 // 2) inline caches (isIC() == true)
70 // 3) runtime calls (isRuntimeCall() == true)
71 // 4) internal word ref (isInternalWord() == true)
72 // 5) external word ref (isExternalWord() == true)
73 //
74 // when objects move (GC) or if code moves (compacting the code heap).
75 // They are also used to patch the code (if a call site must change)
76 //
77 // A relocInfo is represented in 16 bits:
78 // 4 bits indicating the relocation type
79 // 12 bits indicating the offset from the previous relocInfo address
80 //
81 // The offsets accumulate along the relocInfo stream to encode the
82 // address within the CodeBlob, which is named RelocIterator::addr().
83 // The address of a particular relocInfo always points to the first
84 // byte of the relevant instruction (and not to any of its subfields
85 // or embedded immediate constants).
86 //
87 // The offset value is scaled appropriately for the target machine.
88 // (See relocInfo_<arch>.hpp for the offset scaling.)
89 //
90 // On some machines, there may also be a "format" field which may provide
91 // additional information about the format of the instruction stream
92 // at the corresponding code address. The format value is usually zero.
93 // Any machine (such as Intel) whose instructions can sometimes contain
94 // more than one relocatable constant needs format codes to distinguish
95 // which operand goes with a given relocation.
96 //
97 // If the target machine needs N format bits, the offset has 12-N bits,
98 // the format is encoded between the offset and the type, and the
99 // relocInfo_<arch>.hpp file has manifest constants for the format codes.
100 //
101 // If the type is "data_prefix_tag" then the offset bits are further encoded,
102 // and in fact represent not a code-stream offset but some inline data.
103 // The data takes the form of a counted sequence of halfwords, which
104 // precedes the actual relocation record. (Clients never see it directly.)
105 // The interpretation of this extra data depends on the relocation type.
106 //
107 // On machines that have 32-bit immediate fields, there is usually
108 // little need for relocation "prefix" data, because the instruction stream
109 // is a perfectly reasonable place to store the value. On machines in
110 // which 32-bit values must be "split" across instructions, the relocation
111 // data is the "true" specification of the value, which is then applied
112 // to some field of the instruction (22 or 13 bits, on SPARC).
113 //
114 // Whenever the location of the CodeBlob changes, any PC-relative
115 // relocations, and any internal_word_type relocations, must be reapplied.
116 // After the GC runs, oop_type relocations must be reapplied.
117 //
118 //
119 // Here are meanings of the types:
120 //
121 // relocInfo::none -- a filler record
122 // Value: none
123 // Instruction: The corresponding code address is ignored
124 // Data: Any data prefix and format code are ignored
125 // (This means that any relocInfo can be disabled by setting
126 // its type to none. See relocInfo::remove.)
127 //
128 // relocInfo::oop_type, relocInfo::metadata_type -- a reference to an oop or meta data
129 // Value: an oop, or else the address (handle) of an oop
130 // Instruction types: memory (load), set (load address)
131 // Data: [] an oop stored in 4 bytes of instruction
132 // [[N]n] the index of an oop in the CodeBlob's oop pool
133 //
134 // relocInfo::internal_word_type -- an address within the same CodeBlob
135 // relocInfo::section_word_type -- same, but can refer to another section
136 // Value: an address in the CodeBlob's code or constants section
137 // Instruction types: memory (load), set (load address)
138 // Data: [] stored in 4 bytes of instruction
139 // [[L]l] a relative offset (see [About Offsets] below)
140 // In the case of section_word_type, the offset is relative to a section
141 // base address, and the section number (e.g., SECT_INSTS) is encoded
142 // into the low two bits of the offset L.
143 //
144 // relocInfo::external_word_type -- a fixed address in the runtime system
145 // Value: an address
146 // Instruction types: memory (load), set (load address)
147 // Data: [] stored in 4 bytes of instruction
148 // [n] the index of a "well-known" stub (usual case on RISC)
149 // [Ll] a 32-bit address
150 //
151 // relocInfo::runtime_call_type -- a fixed subroutine in the runtime system
152 // Value: an address
153 // Instruction types: PC-relative call (or a PC-relative branch)
154 // Data: [] stored in 4 bytes of instruction
155 //
156 // relocInfo::static_call_type -- a static call
157 // Value: an CodeBlob, a stub, or a fixup routine
158 // Instruction types: a call
159 // Data: []
160 // The identity of the callee is extracted from debugging information.
161 // //%note reloc_3
162 //
163 // relocInfo::virtual_call_type -- a virtual call site (which includes an inline
164 // cache)
165 // Value: an CodeBlob, a stub, the interpreter, or a fixup routine
166 // Instruction types: a call, plus some associated set-oop instructions
167 // Data: [] the associated set-oops are adjacent to the call
168 // [n] n is a relative offset to the first set-oop
169 // [[N]n l] and l is a limit within which the set-oops occur
170 // [Nn Ll] both n and l may be 32 bits if necessary
171 // The identity of the callee is extracted from debugging information.
172 //
173 // relocInfo::opt_virtual_call_type -- a virtual call site that is statically bound
174 //
175 // Same info as a static_call_type. We use a special type, so the handling of
176 // virtuals and statics are separated.
177 //
178 //
179 // The offset n points to the first set-oop. (See [About Offsets] below.)
180 // In turn, the set-oop instruction specifies or contains an oop cell devoted
181 // exclusively to the IC call, which can be patched along with the call.
182 //
183 // The locations of any other set-oops are found by searching the relocation
184 // information starting at the first set-oop, and continuing until all
185 // relocations up through l have been inspected. The value l is another
186 // relative offset. (Both n and l are relative to the call's first byte.)
187 //
188 // The limit l of the search is exclusive. However, if it points within
189 // the call (e.g., offset zero), it is adjusted to point after the call and
190 // any associated machine-specific delay slot.
191 //
192 // Since the offsets could be as wide as 32-bits, these conventions
193 // put no restrictions whatever upon code reorganization.
194 //
195 // The compiler is responsible for ensuring that transition from a clean
196 // state to a monomorphic compiled state is MP-safe. This implies that
197 // the system must respond well to intermediate states where a random
198 // subset of the set-oops has been correctly from the clean state
199 // upon entry to the VEP of the compiled method. In the case of a
200 // machine (Intel) with a single set-oop instruction, the 32-bit
201 // immediate field must not straddle a unit of memory coherence.
202 // //%note reloc_3
203 //
204 // relocInfo::static_stub_type -- an extra stub for each static_call_type
205 // Value: none
206 // Instruction types: a virtual call: { set_oop; jump; }
207 // Data: [[N]n] the offset of the associated static_call reloc
208 // This stub becomes the target of a static call which must be upgraded
209 // to a virtual call (because the callee is interpreted).
210 // See [About Offsets] below.
211 // //%note reloc_2
212 //
213 // relocInfo::poll_[return_]type -- a safepoint poll
214 // Value: none
215 // Instruction types: memory load or test
216 // Data: none
217 //
218 // For example:
219 //
220 // INSTRUCTIONS RELOC: TYPE PREFIX DATA
221 // ------------ ---- -----------
222 // sethi %hi(myObject), R oop_type [n(myObject)]
223 // ld [R+%lo(myObject)+fldOffset], R2 oop_type [n(myObject) fldOffset]
224 // add R2, 1, R2
225 // st R2, [R+%lo(myObject)+fldOffset] oop_type [n(myObject) fldOffset]
226 //%note reloc_1
227 //
228 // This uses 4 instruction words, 8 relocation halfwords,
229 // and an entry (which is shareable) in the CodeBlob's oop pool,
230 // for a total of 36 bytes.
231 //
232 // Note that the compiler is responsible for ensuring the "fldOffset" when
233 // added to "%lo(myObject)" does not overflow the immediate fields of the
234 // memory instructions.
235 //
236 //
237 // [About Offsets] Relative offsets are supplied to this module as
238 // positive byte offsets, but they may be internally stored scaled
239 // and/or negated, depending on what is most compact for the target
240 // system. Since the object pointed to by the offset typically
241 // precedes the relocation address, it is profitable to store
242 // these negative offsets as positive numbers, but this decision
243 // is internal to the relocation information abstractions.
244 //
245
246 class Relocation;
247 class CodeBuffer;
248 class CodeSection;
249 class RelocIterator;
250
251 class relocInfo {
252 friend class RelocIterator;
253 public:
254 enum relocType {
255 none = 0, // Used when no relocation should be generated
256 oop_type = 1, // embedded oop
257 virtual_call_type = 2, // a standard inline cache call for a virtual send
258 opt_virtual_call_type = 3, // a virtual call that has been statically bound (i.e., no IC cache)
259 static_call_type = 4, // a static send
260 static_stub_type = 5, // stub-entry for static send (takes care of interpreter case)
261 runtime_call_type = 6, // call to fixed external routine
262 external_word_type = 7, // reference to fixed external address
263 internal_word_type = 8, // reference within the current code blob
264 section_word_type = 9, // internal, but a cross-section reference
265 poll_type = 10, // polling instruction for safepoints
266 poll_return_type = 11, // polling instruction for safepoints at return
267 metadata_type = 12, // metadata that used to be oops
268 trampoline_stub_type = 13, // stub-entry for trampoline
269 runtime_call_w_cp_type = 14, // Runtime call which may load its target from the constant pool
270 data_prefix_tag = 15, // tag for a prefix (carries data arguments)
271 post_call_nop_type = 16, // A tag for post call nop relocations
272 entry_guard_type = 17, // A tag for an nmethod entry barrier guard value
273 barrier_type = 18, // GC barrier data
274 type_mask = 31 // A mask which selects only the above values
275 };
276
277 private:
278 unsigned short _value;
279
280 static const enum class RawBitsToken {} RAW_BITS{};
281
282 relocInfo(relocType type, RawBitsToken, int bits)
283 : _value(checked_cast<unsigned short>((type << nontype_width) + bits)) { }
284
285 static relocType check_relocType(relocType type) NOT_DEBUG({ return type; });
286
287 static void check_offset_and_format(int offset, int format) NOT_DEBUG_RETURN;
288
289 static int compute_bits(int offset, int format) {
290 check_offset_and_format(offset, format);
291 return (offset / offset_unit) + (format << offset_width);
292 }
293
294 public:
295 relocInfo(relocType type, int offset, int format = 0)
296 : relocInfo(check_relocType(type), RAW_BITS, compute_bits(offset, format)) {}
297
298 #define APPLY_TO_RELOCATIONS(visitor) \
299 visitor(oop) \
300 visitor(metadata) \
301 visitor(virtual_call) \
302 visitor(opt_virtual_call) \
303 visitor(static_call) \
304 visitor(static_stub) \
305 visitor(runtime_call) \
306 visitor(runtime_call_w_cp) \
307 visitor(external_word) \
308 visitor(internal_word) \
309 visitor(poll) \
310 visitor(poll_return) \
311 visitor(section_word) \
312 visitor(trampoline_stub) \
313 visitor(post_call_nop) \
314 visitor(entry_guard) \
315 visitor(barrier) \
316
317
318 public:
319 enum : unsigned short{
320 value_width = sizeof(unsigned short) * BitsPerByte,
321 type_width = 5, // == log2(type_mask+1)
322 nontype_width = value_width - type_width,
323 datalen_width = nontype_width-1,
324 datalen_tag = 1 << datalen_width, // or-ed into _value
325 datalen_limit = 1 << datalen_width,
326 datalen_mask = (1 << datalen_width)-1
327 };
328
329 // accessors
330 public:
331 relocType type() const { return (relocType)((unsigned)_value >> nontype_width); }
332 int format() const { return format_mask==0? 0: format_mask &
333 ((unsigned)_value >> offset_width); }
334 int addr_offset() const { assert(!is_prefix(), "must have offset");
335 return (_value & offset_mask)*offset_unit; }
336
337 protected:
338 const short* data() const { assert(is_datalen(), "must have data");
339 return (const short*)(this + 1); }
340 unsigned short datalen() const { assert(is_datalen(), "must have data");
341 return (_value & datalen_mask); }
342 unsigned short immediate() const { assert(is_immediate(), "must have immed");
343 return (_value & datalen_mask); }
344 public:
345 static int addr_unit() { return offset_unit; }
346 static int offset_limit() { return (1 << offset_width) * offset_unit; }
347
348 void set_type(relocType type);
349
350 void remove() { set_type(none); }
351
352 protected:
353 bool is_none() const { return type() == none; }
354 bool is_prefix() const { return type() == data_prefix_tag; }
355 bool is_datalen() const { assert(is_prefix(), "must be prefix");
356 return (_value & datalen_tag) != 0; }
357 bool is_immediate() const { assert(is_prefix(), "must be prefix");
358 return (_value & datalen_tag) == 0; }
359
360 public:
361 // Occasionally records of type relocInfo::none will appear in the stream.
362 // We do not bother to filter these out, but clients should ignore them.
363 // These records serve as "filler" in three ways:
364 // - to skip large spans of unrelocated code (this is rare)
365 // - to pad out the relocInfo array to the required oop alignment
366 // - to disable old relocation information which is no longer applicable
367
368 static relocInfo filler_info() {
369 return relocInfo(relocInfo::none, relocInfo::offset_limit() - relocInfo::offset_unit);
370 }
371
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.)
379
380 static relocInfo prefix_info(int datalen = 0) {
381 assert(relocInfo::fits_into_immediate(datalen), "datalen in limits");
382 return relocInfo(relocInfo::data_prefix_tag, relocInfo::RAW_BITS, relocInfo::datalen_tag | datalen);
383 }
384
385 private:
386 // an immediate relocInfo optimizes a prefix with one 10-bit unsigned value
387 static relocInfo immediate_relocInfo(int data0) {
388 assert(fits_into_immediate(data0), "data0 in limits");
389 return relocInfo(relocInfo::data_prefix_tag, RAW_BITS, data0);
390 }
391 static bool fits_into_immediate(int data0) {
392 return (data0 >= 0 && data0 < datalen_limit);
393 }
394
395 public:
396 // Support routines for compilers.
397
398 // This routine takes an infant relocInfo (unprefixed) and
399 // edits in its prefix, if any. It also updates dest.locs_end.
400 void initialize(CodeSection* dest, Relocation* reloc);
401
402 // This routine updates a prefix and returns the limit pointer.
403 // It tries to compress the prefix from 32 to 16 bits, and if
404 // successful returns a reduced "prefix_limit" pointer.
405 relocInfo* finish_prefix(short* prefix_limit);
406
407 // bit-packers for the data array:
408
409 // As it happens, the bytes within the shorts are ordered natively,
410 // but the shorts within the word are ordered big-endian.
411 // This is an arbitrary choice, made this way mainly to ease debugging.
412 static short data0_from_int(jint x) { return (short)(x >> value_width); }
413 static short data1_from_int(jint x) { return (short)x; }
414 static jint jint_from_data(short* data) {
415 return (data[0] << value_width) + (unsigned short)data[1];
416 }
417
418 static jint short_data_at(int n, short* data, int datalen) {
419 return datalen > n ? data[n] : 0;
420 }
421
422 static jint jint_data_at(int n, short* data, int datalen) {
423 return datalen > n+1 ? jint_from_data(&data[n]) : short_data_at(n, data, datalen);
424 }
425
426 // Update methods for relocation information
427 // (since code is dynamically patched, we also need to dynamically update the relocation info)
428 // Both methods takes old_type, so it is able to perform sanity checks on the information removed.
429 static void change_reloc_info_for_address(RelocIterator *itr, address pc, relocType old_type, relocType new_type);
430
431 // Machine dependent stuff
432 #include CPU_HEADER(relocInfo)
433
434 protected:
435 // Derived constant, based on format_width which is PD:
436 enum {
437 offset_width = nontype_width - format_width,
438 offset_mask = (1<<offset_width) - 1,
439 format_mask = (1<<format_width) - 1
440 };
441 public:
442 enum {
443 #ifdef _LP64
444 // for use in format
445 // format_width must be at least 1 on _LP64
446 narrow_oop_in_const = 1,
447 #endif
448 // Conservatively large estimate of maximum length (in shorts)
449 // of any relocation record.
450 // Extended format is length prefix, data words, and tag/offset suffix.
451 length_limit = 1 + 1 + (3*BytesPerWord/BytesPerShort) + 1,
452 have_format = format_width > 0
453 };
454
455 static const char* type_name(relocInfo::relocType t);
456 };
457
458 #define FORWARD_DECLARE_EACH_CLASS(name) \
459 class name##_Relocation;
460 APPLY_TO_RELOCATIONS(FORWARD_DECLARE_EACH_CLASS)
461 #undef FORWARD_DECLARE_EACH_CLASS
462
463 // Holder for flyweight relocation objects.
464 // Although the flyweight subclasses are of varying sizes,
465 // the holder is "one size fits all".
466 class RelocationHolder {
467 friend class Relocation;
468
469 private:
470 // A Relocation is "held" by placement constructing a Relocation into
471 // _relocbuf. Hence, _relocbuf must accomodate all subclasses of
472 // Relocation. We also need the Relocation base class to be at the same
473 // address as the start of the object, e.g. at the address of _relocbuf.
474 // Both of these requirements are checked (see emplace_relocation).
475 // The placement of the base class subobject isn't guaranteed by C++, since
476 // these aren't standard layout classes, but all supported implementations
477 // provide that behavior. If that changes, we can instead add a Relocation*
478 // _reloc member to capture the result of the placement new, and use that to
479 // access the base subobject.
480 static const size_t _relocbuf_size = 5 * sizeof(void*);
481 alignas(void*) char _relocbuf[_relocbuf_size];
482
483 template<typename Reloc, typename... Args>
484 void emplace_relocation(const Args&... args) {
485 static_assert(std::is_base_of<Relocation, Reloc>::value, "not Relocation");
486 static_assert(sizeof(Reloc) <= sizeof(_relocbuf), "_relocbuf too small");
487 Relocation* reloc = ::new (_relocbuf) Reloc(args...);
488 // Verify the base class subobject of the object constructed into
489 // _relocbuf is at the same address as the derived object.
490 assert(static_cast<const void*>(reloc) == _relocbuf, "invariant");
491 }
492
493 // Support for Relocation::copy_into.
494 // reloc should be a most derived object.
495 template<typename Reloc>
496 void copy_into_impl(const Reloc& reloc) {
497 emplace_relocation<Reloc>(reloc);
498 }
499
500 // Tag for selecting the constructor below and carrying the type of the
501 // relocation object the new holder will (initially) contain.
502 template<typename Reloc> struct Construct {};
503
504 // Constructor used by construct(). Constructs a new holder containing a
505 // relocation of type Reloc that is constructed using the provided args.
506 template<typename Reloc, typename... Args>
507 RelocationHolder(Construct<Reloc>, const Args&... args) {
508 emplace_relocation<Reloc>(args...);
509 }
510
511 public:
512 Relocation* reloc() const { return (Relocation*)_relocbuf; }
513 inline relocInfo::relocType type() const;
514
515 // Return a holder containing a relocation of type Reloc, constructed using args.
516 template<typename Reloc, typename... Args>
517 static RelocationHolder construct(const Args&... args) {
518 return RelocationHolder(Construct<Reloc>(), args...);
519 }
520
521 RelocationHolder(); // Initializes type to none.
522
523 // Depends on the destructor for all relocation types being trivial
524 // (verified in .cpp file).
525 ~RelocationHolder() = default;
526
527 RelocationHolder(const RelocationHolder& from);
528 RelocationHolder& operator=(const RelocationHolder& from);
529
530 static const RelocationHolder none;
531 };
532
533 // A RelocIterator iterates through the relocation information of a CodeBlob.
534 // It provides access to successive relocations as it is advanced through a
535 // code stream.
536 // Usage:
537 // RelocIterator iter(nm);
538 // while (iter.next()) {
539 // iter.reloc()->some_operation();
540 // }
541 // or:
542 // RelocIterator iter(nm);
543 // while (iter.next()) {
544 // switch (iter.type()) {
545 // case relocInfo::oop_type :
546 // case relocInfo::ic_type :
547 // case relocInfo::prim_type :
548 // case relocInfo::uncommon_type :
549 // case relocInfo::runtime_call_type :
550 // case relocInfo::internal_word_type:
551 // case relocInfo::external_word_type:
552 // ...
553 // }
554 // }
555
556 class RelocIterator : public StackObj {
557 friend class section_word_Relocation; // for section verification
558 enum { SECT_LIMIT = 3 }; // must be equal to CodeBuffer::SECT_LIMIT, checked in ctor
559 friend class Relocation;
560 friend class relocInfo; // for change_reloc_info_for_address only
561 typedef relocInfo::relocType relocType;
562
563 private:
564 address _limit; // stop producing relocations after this _addr
565 relocInfo* _current; // the current relocation information
566 relocInfo* _end; // end marker; we're done iterating when _current == _end
567 nmethod* _code; // compiled method containing _addr
568 address _addr; // instruction to which the relocation applies
569 short _databuf; // spare buffer for compressed data
570 short* _data; // pointer to the relocation's data
571 short _datalen; // number of halfwords in _data
572
573 // Base addresses needed to compute targets of section_word_type relocs.
574 address _section_start[SECT_LIMIT];
575 address _section_end [SECT_LIMIT];
576
577 void set_has_current(bool b) {
578 _datalen = !b ? -1 : 0;
579 debug_only(_data = nullptr);
580 }
581 void set_current(relocInfo& ri) {
582 _current = &ri;
583 set_has_current(true);
584 }
585
586 RelocationHolder _rh; // where the current relocation is allocated
587
588 relocInfo* current() const { assert(has_current(), "must have current");
589 return _current; }
590
591 void set_limits(address begin, address limit);
592
593 void advance_over_prefix(); // helper method
594
595 void initialize_misc();
596
597 void initialize(nmethod* nm, address begin, address limit);
598
599 RelocIterator() { initialize_misc(); }
600
601 public:
602 // constructor
603 RelocIterator(nmethod* nm, address begin = nullptr, address limit = nullptr);
604 RelocIterator(CodeSection* cb, address begin = nullptr, address limit = nullptr);
605
606 // get next reloc info, return !eos
607 bool next() {
608 _current++;
609 assert(_current <= _end, "must not overrun relocInfo");
610 if (_current == _end) {
611 set_has_current(false);
612 return false;
613 }
614 set_has_current(true);
615
616 if (_current->is_prefix()) {
617 advance_over_prefix();
618 assert(!current()->is_prefix(), "only one prefix at a time");
619 }
620
621 _addr += _current->addr_offset();
622
623 if (_limit != nullptr && _addr >= _limit) {
624 set_has_current(false);
625 return false;
626 }
627
628 return true;
629 }
630
631 // accessors
632 address limit() const { return _limit; }
633 relocType type() const { return current()->type(); }
634 int format() const { return (relocInfo::have_format) ? current()->format() : 0; }
635 address addr() const { return _addr; }
636 nmethod* code() const { return _code; }
637 short* data() const { return _data; }
638 int datalen() const { return _datalen; }
639 bool has_current() const { return _datalen >= 0; }
640 bool addr_in_const() const;
641
642 address section_start(int n) const {
643 assert(_section_start[n], "section %d must be initialized", n);
644 return _section_start[n];
645 }
646 address section_end(int n) const {
647 assert(_section_end[n], "section %d must be initialized", n);
648 return _section_end[n];
649 }
650
651 // The address points to the affected displacement part of the instruction.
652 // For RISC, this is just the whole instruction.
653 // For Intel, this is an unaligned 32-bit word.
654
655 // type-specific relocation accessors: oop_Relocation* oop_reloc(), etc.
656 #define EACH_TYPE(name) \
657 inline name##_Relocation* name##_reloc();
658 APPLY_TO_RELOCATIONS(EACH_TYPE)
659 #undef EACH_TYPE
660 // generic relocation accessor; switches on type to call the above
661 Relocation* reloc();
662
663 public:
664 void print_on(outputStream* st);
665 void print_current_on(outputStream* st);
666 };
667
668
669 // A Relocation is a flyweight object allocated within a RelocationHolder.
670 // It represents the relocation data of relocation record.
671 // So, the RelocIterator unpacks relocInfos into Relocations.
672
673 class Relocation {
674 friend class RelocIterator;
675 friend class SCCReader;
676
677 private:
678 // When a relocation has been created by a RelocIterator,
679 // this field is non-null. It allows the relocation to know
680 // its context, such as the address to which it applies.
681 RelocIterator* _binding;
682
683 relocInfo::relocType _rtype;
684
685 protected:
686 RelocIterator* binding() const {
687 assert(_binding != nullptr, "must be bound");
688 return _binding;
689 }
690 void set_binding(RelocIterator* b) {
691 assert(_binding == nullptr, "must be unbound");
692 _binding = b;
693 assert(_binding != nullptr, "must now be bound");
694 }
695
696 explicit Relocation(relocInfo::relocType rtype) : _binding(nullptr), _rtype(rtype) { }
697
698 // Helper for copy_into functions for derived classes.
699 // Forwards operation to RelocationHolder::copy_into_impl so that
700 // RelocationHolder only needs to befriend this class, rather than all
701 // derived classes that implement copy_into.
702 template<typename Reloc>
703 static void copy_into_helper(const Reloc& reloc, RelocationHolder& holder) {
704 holder.copy_into_impl(reloc);
705 }
706
707 public:
708 // make a generic relocation for a given type (if possible)
709 static RelocationHolder spec_simple(relocInfo::relocType rtype);
710
711 // here is the type-specific hook which writes relocation data:
712 virtual void pack_data_to(CodeSection* dest) { }
713
714 // here is the type-specific hook which reads (unpacks) relocation data:
715 virtual void unpack_data() {
716 assert(datalen()==0 || type()==relocInfo::none, "no data here");
717 }
718
719 protected:
720 // Helper functions for pack_data_to() and unpack_data().
721
722 // Most of the compression logic is confined here.
723 // (The "immediate data" mechanism of relocInfo works independently
724 // of this stuff, and acts to further compress most 1-word data prefixes.)
725
726 // A variable-width int is encoded as a short if it will fit in 16 bits.
727 // The decoder looks at datalen to decide whether to unpack short or jint.
728 // Most relocation records are quite simple, containing at most two ints.
729
730 static bool is_short(jint x) { return x == (short)x; }
731 static short* add_short(short* p, short x) { *p++ = x; return p; }
732 static short* add_jint (short* p, jint x) {
733 *p++ = relocInfo::data0_from_int(x); *p++ = relocInfo::data1_from_int(x);
734 return p;
735 }
736 static short* add_var_int(short* p, jint x) { // add a variable-width int
737 if (is_short(x)) p = add_short(p, (short)x);
738 else p = add_jint (p, x);
739 return p;
740 }
741
742 static short* pack_1_int_to(short* p, jint x0) {
743 // Format is one of: [] [x] [Xx]
744 if (x0 != 0) p = add_var_int(p, x0);
745 return p;
746 }
747 int unpack_1_int() {
748 assert(datalen() <= 2, "too much data");
749 return relocInfo::jint_data_at(0, data(), datalen());
750 }
751
752 // With two ints, the short form is used only if both ints are short.
753 short* pack_2_ints_to(short* p, jint x0, jint x1) {
754 // Format is one of: [] [x y?] [Xx Y?y]
755 if (x0 == 0 && x1 == 0) {
756 // no halfwords needed to store zeroes
757 } else if (is_short(x0) && is_short(x1)) {
758 // 1-2 halfwords needed to store shorts
759 p = add_short(p, (short)x0); if (x1!=0) p = add_short(p, (short)x1);
760 } else {
761 // 3-4 halfwords needed to store jints
762 p = add_jint(p, x0); p = add_var_int(p, x1);
763 }
764 return p;
765 }
766 void unpack_2_ints(jint& x0, jint& x1) {
767 int dlen = datalen();
768 short* dp = data();
769 if (dlen <= 2) {
770 x0 = relocInfo::short_data_at(0, dp, dlen);
771 x1 = relocInfo::short_data_at(1, dp, dlen);
772 } else {
773 assert(dlen <= 4, "too much data");
774 x0 = relocInfo::jint_data_at(0, dp, dlen);
775 x1 = relocInfo::jint_data_at(2, dp, dlen);
776 }
777 }
778
779 protected:
780 // platform-independent utility for patching constant section
781 void const_set_data_value (address x);
782 void const_verify_data_value (address x);
783 // platform-dependent utilities for decoding and patching instructions
784 void pd_set_data_value (address x, bool verify_only = false); // a set or mem-ref
785 void pd_verify_data_value (address x) { pd_set_data_value(x, true); }
786 address pd_call_destination (address orig_addr = nullptr);
787 void pd_set_call_destination (address x);
788
789 // this extracts the address of an address in the code stream instead of the reloc data
790 address* pd_address_in_code ();
791
792 // this extracts an address from the code stream instead of the reloc data
793 address pd_get_address_from_code ();
794
795 // these convert from byte offsets, to scaled offsets, to addresses
796 static jint scaled_offset(address x, address base) {
797 int byte_offset = checked_cast<int>(x - base);
798 int offset = -byte_offset / relocInfo::addr_unit();
799 assert(address_from_scaled_offset(offset, base) == x, "just checkin'");
800 return offset;
801 }
802 static jint scaled_offset_null_special(address x, address base) {
803 // Some relocations treat offset=0 as meaning nullptr.
804 // Handle this extra convention carefully.
805 if (x == nullptr) return 0;
806 assert(x != base, "offset must not be zero");
807 return scaled_offset(x, base);
808 }
809 static address address_from_scaled_offset(jint offset, address base) {
810 int byte_offset = -( offset * relocInfo::addr_unit() );
811 return base + byte_offset;
812 }
813
814 // helpers for mapping between old and new addresses after a move or resize
815 address old_addr_for(address newa, const CodeBuffer* src, CodeBuffer* dest);
816 address new_addr_for(address olda, const CodeBuffer* src, CodeBuffer* dest);
817 void normalize_address(address& addr, const CodeSection* dest, bool allow_other_sections = false);
818
819 public:
820 // accessors which only make sense for a bound Relocation
821 address addr() const { return binding()->addr(); }
822 nmethod* code() const { return binding()->code(); }
823 bool addr_in_const() const { return binding()->addr_in_const(); }
824 protected:
825 short* data() const { return binding()->data(); }
826 int datalen() const { return binding()->datalen(); }
827
828 public:
829 // Make a filler relocation.
830 Relocation() : Relocation(relocInfo::none) {}
831
832 // Intentionally public non-virtual destructor, even though polymorphic. We
833 // never heap allocate a Relocation, so never delete through a base pointer.
834 // RelocationHolder depends on the destructor for all relocation types being
835 // trivial, so this must not be virtual (and hence non-trivial).
836 ~Relocation() = default;
837
838 int format() const { return binding()->format(); }
839
840 relocInfo::relocType type() const { return _rtype; }
841
842 // Copy this relocation into holder.
843 virtual void copy_into(RelocationHolder& holder) const;
844
845 // is it a call instruction?
846 virtual bool is_call() { return false; }
847
848 // is it a data movement instruction?
849 virtual bool is_data() { return false; }
850
851 // some relocations can compute their own values
852 virtual address value();
853
854 // all relocations are able to reassert their values
855 virtual void set_value(address x);
856
857 virtual void clear_inline_cache() {}
858
859 // This method assumes that all virtual/static (inline) caches are cleared (since for static_call_type and
860 // ic_call_type is not always position dependent (depending on the state of the cache)). However, this is
861 // probably a reasonable assumption, since empty caches simplifies code reloacation.
862 virtual void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest) { }
863 };
864
865
866 // certain inlines must be deferred until class Relocation is defined:
867
868 inline RelocationHolder::RelocationHolder() :
869 RelocationHolder(Construct<Relocation>())
870 {}
871
872 inline RelocationHolder::RelocationHolder(const RelocationHolder& from) {
873 from.reloc()->copy_into(*this);
874 }
875
876 inline RelocationHolder& RelocationHolder::operator=(const RelocationHolder& from) {
877 // All Relocation types are trivially destructible (verified in .cpp file),
878 // so we don't need to destruct our old value before copying over it.
879 // If not for that we would need to decide what to do about self-assignment.
880 from.reloc()->copy_into(*this);
881 return *this;
882 }
883
884 relocInfo::relocType RelocationHolder::type() const {
885 return reloc()->type();
886 }
887
888 // A DataRelocation always points at a memory or load-constant instruction..
889 // It is absolute on most machines, and the constant is split on RISCs.
890 // The specific subtypes are oop, external_word, and internal_word.
891 class DataRelocation : public Relocation {
892 public:
893 DataRelocation(relocInfo::relocType type) : Relocation(type) {}
894
895 bool is_data() override { return true; }
896
897 // target must be computed somehow from relocation data
898 address value() override = 0;
899 void set_value(address x) override {
900 if (addr_in_const()) {
901 const_set_data_value(x);
902 } else {
903 pd_set_data_value(x);
904 }
905 }
906 void verify_value(address x) {
907 if (addr_in_const()) {
908 const_verify_data_value(x);
909 } else {
910 pd_verify_data_value(x);
911 }
912 }
913 };
914
915 class post_call_nop_Relocation : public Relocation {
916 friend class RelocationHolder;
917
918 public:
919 post_call_nop_Relocation() : Relocation(relocInfo::post_call_nop_type) { }
920
921 static RelocationHolder spec() {
922 return RelocationHolder::construct<post_call_nop_Relocation>();
923 }
924
925 void copy_into(RelocationHolder& holder) const override;
926 };
927
928 class entry_guard_Relocation : public Relocation {
929 friend class RelocationHolder;
930
931 public:
932 entry_guard_Relocation() : Relocation(relocInfo::entry_guard_type) { }
933
934 static RelocationHolder spec() {
935 return RelocationHolder::construct<entry_guard_Relocation>();
936 }
937
938 void copy_into(RelocationHolder& holder) const override;
939 };
940
941 // A CallRelocation always points at a call instruction.
942 // It is PC-relative on most machines.
943 class CallRelocation : public Relocation {
944 public:
945 CallRelocation(relocInfo::relocType type) : Relocation(type) { }
946
947 bool is_call() override { return true; }
948
949 address destination() { return pd_call_destination(); }
950 void set_destination(address x); // pd_set_call_destination
951
952 void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest) override;
953 address value() override { return destination(); }
954 void set_value(address x) override { set_destination(x); }
955 };
956
957 class oop_Relocation : public DataRelocation {
958 public:
959 // an oop in the CodeBlob's oop pool; encoded as [n] or [Nn]
960 static RelocationHolder spec(int oop_index) {
961 assert(oop_index > 0, "must be a pool-resident oop");
962 return RelocationHolder::construct<oop_Relocation>(oop_index);
963 }
964 // an oop in the instruction stream; encoded as []
965 static RelocationHolder spec_for_immediate() {
966 // If no immediate oops are generated, we can skip some walks over nmethods.
967 // Assert that they don't get generated accidentally!
968 assert(relocInfo::mustIterateImmediateOopsInCode(),
969 "Must return true so we will search for oops as roots etc. in the code.");
970 const int oop_index = 0;
971 return RelocationHolder::construct<oop_Relocation>(oop_index);
972 }
973
974 void copy_into(RelocationHolder& holder) const override;
975
976 private:
977 jint _oop_index; // if > 0, index into CodeBlob::oop_at
978
979 oop_Relocation(int oop_index)
980 : DataRelocation(relocInfo::oop_type), _oop_index(oop_index) { }
981
982 friend class RelocationHolder;
983 oop_Relocation() : DataRelocation(relocInfo::oop_type) {}
984
985 public:
986 int oop_index() { return _oop_index; }
987
988 // oop_index is packed in "1_int" format: [n] or [Nn]
989 void pack_data_to(CodeSection* dest) override;
990 void unpack_data() override;
991
992 void fix_oop_relocation(); // reasserts oop value
993
994 void verify_oop_relocation();
995
996 address value() override { return *reinterpret_cast<address*>(oop_addr()); }
997
998 bool oop_is_immediate() { return oop_index() == 0; }
999
1000 oop* oop_addr(); // addr or &pool[jint_data]
1001 oop oop_value(); // *oop_addr
1002 // Note: oop_value transparently converts Universe::non_oop_word to nullptr.
1003 };
1004
1005
1006 // copy of oop_Relocation for now but may delete stuff in both/either
1007 class metadata_Relocation : public DataRelocation {
1008
1009 public:
1010 // an metadata in the CodeBlob's metadata pool; encoded as [n] or [Nn]
1011 static RelocationHolder spec(int metadata_index) {
1012 assert(metadata_index > 0, "must be a pool-resident metadata");
1013 return RelocationHolder::construct<metadata_Relocation>(metadata_index);
1014 }
1015 // an metadata in the instruction stream; encoded as []
1016 static RelocationHolder spec_for_immediate() {
1017 const int metadata_index = 0;
1018 return RelocationHolder::construct<metadata_Relocation>(metadata_index);
1019 }
1020
1021 void copy_into(RelocationHolder& holder) const override;
1022
1023 private:
1024 jint _metadata_index; // if > 0, index into nmethod::metadata_at
1025
1026 metadata_Relocation(int metadata_index)
1027 : DataRelocation(relocInfo::metadata_type), _metadata_index(metadata_index) { }
1028
1029 friend class RelocationHolder;
1030 metadata_Relocation() : DataRelocation(relocInfo::metadata_type) { }
1031
1032 // Fixes a Metadata pointer in the code. Most platforms embeds the
1033 // Metadata pointer in the code at compile time so this is empty
1034 // for them.
1035 void pd_fix_value(address x);
1036
1037 public:
1038 int metadata_index() { return _metadata_index; }
1039
1040 // metadata_index is packed in "1_int" format: [n] or [Nn]
1041 void pack_data_to(CodeSection* dest) override;
1042 void unpack_data() override;
1043
1044 void fix_metadata_relocation(); // reasserts metadata value
1045
1046 address value() override { return (address) *metadata_addr(); }
1047
1048 bool metadata_is_immediate() { return metadata_index() == 0; }
1049
1050 Metadata** metadata_addr(); // addr or &pool[jint_data]
1051 Metadata* metadata_value(); // *metadata_addr
1052 // Note: metadata_value transparently converts Universe::non_metadata_word to nullptr.
1053 };
1054
1055
1056 class barrier_Relocation : public Relocation {
1057
1058 public:
1059 // The uninitialized value used before the relocation has been patched.
1060 // Code assumes that the unpatched value is zero.
1061 static const int16_t unpatched = 0;
1062
1063 static RelocationHolder spec() {
1064 return RelocationHolder::construct<barrier_Relocation>();
1065 }
1066
1067 void copy_into(RelocationHolder& holder) const override;
1068
1069 private:
1070 friend class RelocIterator;
1071 friend class RelocationHolder;
1072 barrier_Relocation() : Relocation(relocInfo::barrier_type) { }
1073 };
1074
1075
1076 class virtual_call_Relocation : public CallRelocation {
1077
1078 public:
1079 // "cached_value" points to the first associated set-oop.
1080 // The oop_limit helps find the last associated set-oop.
1081 // (See comments at the top of this file.)
1082 static RelocationHolder spec(address cached_value, jint method_index = 0) {
1083 return RelocationHolder::construct<virtual_call_Relocation>(cached_value, method_index);
1084 }
1085
1086 void copy_into(RelocationHolder& holder) const override;
1087
1088 private:
1089 address _cached_value; // location of set-value instruction
1090 jint _method_index; // resolved method for a Java call
1091
1092 virtual_call_Relocation(address cached_value, int method_index)
1093 : CallRelocation(relocInfo::virtual_call_type),
1094 _cached_value(cached_value),
1095 _method_index(method_index) {
1096 assert(cached_value != nullptr, "first oop address must be specified");
1097 }
1098
1099 friend class RelocationHolder;
1100 virtual_call_Relocation() : CallRelocation(relocInfo::virtual_call_type) { }
1101
1102 public:
1103 address cached_value();
1104
1105 int method_index() { return _method_index; }
1106 Method* method_value();
1107
1108 // data is packed as scaled offsets in "2_ints" format: [f l] or [Ff Ll]
1109 // oop_limit is set to 0 if the limit falls somewhere within the call.
1110 // When unpacking, a zero oop_limit is taken to refer to the end of the call.
1111 // (This has the effect of bringing in the call's delay slot on SPARC.)
1112 void pack_data_to(CodeSection* dest) override;
1113 void unpack_data() override;
1114
1115 void clear_inline_cache() override;
1116 };
1117
1118
1119 class opt_virtual_call_Relocation : public CallRelocation {
1120 public:
1121 static RelocationHolder spec(int method_index = 0) {
1122 return RelocationHolder::construct<opt_virtual_call_Relocation>(method_index);
1123 }
1124
1125 void copy_into(RelocationHolder& holder) const override;
1126
1127 private:
1128 jint _method_index; // resolved method for a Java call
1129
1130 opt_virtual_call_Relocation(int method_index)
1131 : CallRelocation(relocInfo::opt_virtual_call_type),
1132 _method_index(method_index) { }
1133
1134 friend class RelocationHolder;
1135 opt_virtual_call_Relocation() : CallRelocation(relocInfo::opt_virtual_call_type) {}
1136
1137 public:
1138 int method_index() { return _method_index; }
1139 Method* method_value();
1140
1141 void pack_data_to(CodeSection* dest) override;
1142 void unpack_data() override;
1143
1144 void clear_inline_cache() override;
1145
1146 // find the matching static_stub
1147 address static_stub();
1148 };
1149
1150
1151 class static_call_Relocation : public CallRelocation {
1152 public:
1153 static RelocationHolder spec(int method_index = 0) {
1154 return RelocationHolder::construct<static_call_Relocation>(method_index);
1155 }
1156
1157 void copy_into(RelocationHolder& holder) const override;
1158
1159 private:
1160 jint _method_index; // resolved method for a Java call
1161
1162 static_call_Relocation(int method_index)
1163 : CallRelocation(relocInfo::static_call_type),
1164 _method_index(method_index) { }
1165
1166 friend class RelocationHolder;
1167 static_call_Relocation() : CallRelocation(relocInfo::static_call_type) {}
1168
1169 public:
1170 int method_index() { return _method_index; }
1171 Method* method_value();
1172
1173 void pack_data_to(CodeSection* dest) override;
1174 void unpack_data() override;
1175
1176 void clear_inline_cache() override;
1177
1178 // find the matching static_stub
1179 address static_stub();
1180 };
1181
1182 class static_stub_Relocation : public Relocation {
1183 public:
1184 static RelocationHolder spec(address static_call) {
1185 return RelocationHolder::construct<static_stub_Relocation>(static_call);
1186 }
1187
1188 void copy_into(RelocationHolder& holder) const override;
1189
1190 private:
1191 address _static_call; // location of corresponding static_call
1192
1193 static_stub_Relocation(address static_call)
1194 : Relocation(relocInfo::static_stub_type),
1195 _static_call(static_call) { }
1196
1197 friend class RelocationHolder;
1198 static_stub_Relocation() : Relocation(relocInfo::static_stub_type) { }
1199
1200 public:
1201 void clear_inline_cache() override;
1202
1203 address static_call() { return _static_call; }
1204
1205 // data is packed as a scaled offset in "1_int" format: [c] or [Cc]
1206 void pack_data_to(CodeSection* dest) override;
1207 void unpack_data() override;
1208 };
1209
1210 class runtime_call_Relocation : public CallRelocation {
1211
1212 public:
1213 static RelocationHolder spec() {
1214 return RelocationHolder::construct<runtime_call_Relocation>();
1215 }
1216
1217 void copy_into(RelocationHolder& holder) const override;
1218
1219 private:
1220 friend class RelocationHolder;
1221 runtime_call_Relocation() : CallRelocation(relocInfo::runtime_call_type) { }
1222 };
1223
1224
1225 class runtime_call_w_cp_Relocation : public CallRelocation {
1226 public:
1227 static RelocationHolder spec() {
1228 return RelocationHolder::construct<runtime_call_w_cp_Relocation>();
1229 }
1230
1231 void copy_into(RelocationHolder& holder) const override;
1232
1233 private:
1234 friend class RelocationHolder;
1235 runtime_call_w_cp_Relocation()
1236 : CallRelocation(relocInfo::runtime_call_w_cp_type),
1237 _offset(-4) /* <0 = invalid */ { }
1238
1239 // On z/Architecture, runtime calls are either a sequence
1240 // of two instructions (load destination of call from constant pool + do call)
1241 // or a pc-relative call. The pc-relative call is faster, but it can only
1242 // be used if the destination of the call is not too far away.
1243 // In order to be able to patch a pc-relative call back into one using
1244 // the constant pool, we have to remember the location of the call's destination
1245 // in the constant pool.
1246 int _offset;
1247
1248 public:
1249 void set_constant_pool_offset(int offset) { _offset = offset; }
1250 int get_constant_pool_offset() { return _offset; }
1251 void pack_data_to(CodeSection * dest) override;
1252 void unpack_data() override;
1253 };
1254
1255 // Trampoline Relocations.
1256 // A trampoline allows to encode a small branch in the code, even if there
1257 // is the chance that this branch can not reach all possible code locations.
1258 // If the relocation finds that a branch is too far for the instruction
1259 // in the code, it can patch it to jump to the trampoline where is
1260 // sufficient space for a far branch. Needed on PPC.
1261 class trampoline_stub_Relocation : public Relocation {
1262 #ifdef USE_TRAMPOLINE_STUB_FIX_OWNER
1263 void pd_fix_owner_after_move();
1264 void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest) override;
1265 #endif
1266
1267 public:
1268 static RelocationHolder spec(address static_call) {
1269 return RelocationHolder::construct<trampoline_stub_Relocation>(static_call);
1270 }
1271
1272 void copy_into(RelocationHolder& holder) const override;
1273
1274 private:
1275 address _owner; // Address of the NativeCall that owns the trampoline.
1276
1277 trampoline_stub_Relocation(address owner)
1278 : Relocation(relocInfo::trampoline_stub_type),
1279 _owner(owner) { }
1280
1281 friend class RelocationHolder;
1282 trampoline_stub_Relocation() : Relocation(relocInfo::trampoline_stub_type) { }
1283
1284 public:
1285
1286 // Return the address of the NativeCall that owns the trampoline.
1287 address owner() { return _owner; }
1288
1289 void pack_data_to(CodeSection * dest) override;
1290 void unpack_data() override;
1291 #if defined(AARCH64)
1292 address pd_destination ();
1293 void pd_set_destination (address x);
1294 #endif
1295 address destination() {
1296 #if defined(AARCH64)
1297 return pd_destination();
1298 #else
1299 fatal("trampoline_stub_Relocation::destination() unimplemented");
1300 return (address)-1;
1301 #endif
1302 }
1303 void set_destination(address x) {
1304 #if defined(AARCH64)
1305 pd_set_destination(x);
1306 #else
1307 fatal("trampoline_stub_Relocation::set_destination() unimplemented");
1308 #endif
1309 }
1310
1311 // Find the trampoline stub for a call.
1312 static address get_trampoline_for(address call, nmethod* code);
1313 };
1314
1315 class external_word_Relocation : public DataRelocation {
1316 public:
1317 static RelocationHolder spec(address target) {
1318 assert(target != nullptr, "must not be null");
1319 return RelocationHolder::construct<external_word_Relocation>(target);
1320 }
1321
1322 // Use this one where all 32/64 bits of the target live in the code stream.
1323 // The target must be an intptr_t, and must be absolute (not relative).
1324 static RelocationHolder spec_for_immediate() {
1325 return RelocationHolder::construct<external_word_Relocation>(nullptr);
1326 }
1327
1328 void copy_into(RelocationHolder& holder) const override;
1329
1330 // Some address looking values aren't safe to treat as relocations
1331 // and should just be treated as constants.
1332 static bool can_be_relocated(address target) {
1333 assert(target == nullptr || (uintptr_t)target >= (uintptr_t)OSInfo::vm_page_size(), INTPTR_FORMAT, (intptr_t)target);
1334 return target != nullptr;
1335 }
1336
1337 private:
1338 address _target; // address in runtime
1339
1340 external_word_Relocation(address target)
1341 : DataRelocation(relocInfo::external_word_type), _target(target) { }
1342
1343 friend class RelocationHolder;
1344 external_word_Relocation() : DataRelocation(relocInfo::external_word_type) { }
1345
1346 public:
1347 // data is packed as a well-known address in "1_int" format: [a] or [Aa]
1348 // The function runtime_address_to_index is used to turn full addresses
1349 // to short indexes, if they are pre-registered by the stub mechanism.
1350 // If the "a" value is 0 (i.e., _target is nullptr), the address is stored
1351 // in the code stream. See external_word_Relocation::target().
1352 void pack_data_to(CodeSection* dest) override;
1353 void unpack_data() override;
1354
1355 void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest) override;
1356 address target(); // if _target==nullptr, fetch addr from code stream
1357 address value() override { return target(); }
1358 };
1359
1360 class internal_word_Relocation : public DataRelocation {
1361
1362 public:
1363 static RelocationHolder spec(address target) {
1364 assert(target != nullptr, "must not be null");
1365 return RelocationHolder::construct<internal_word_Relocation>(target);
1366 }
1367
1368 // use this one where all the bits of the target can fit in the code stream:
1369 static RelocationHolder spec_for_immediate() {
1370 return RelocationHolder::construct<internal_word_Relocation>(nullptr);
1371 }
1372
1373 void copy_into(RelocationHolder& holder) const override;
1374
1375 // default section -1 means self-relative
1376 internal_word_Relocation(address target, int section = -1,
1377 relocInfo::relocType type = relocInfo::internal_word_type)
1378 : DataRelocation(type), _target(target), _section(section) { }
1379
1380 protected:
1381 address _target; // address in CodeBlob
1382 int _section; // section providing base address, if any
1383
1384 friend class RelocationHolder;
1385 internal_word_Relocation(relocInfo::relocType type = relocInfo::internal_word_type)
1386 : DataRelocation(type) { }
1387
1388 // bit-width of LSB field in packed offset, if section >= 0
1389 enum { section_width = 2 }; // must equal CodeBuffer::sect_bits
1390
1391 public:
1392 // data is packed as a scaled offset in "1_int" format: [o] or [Oo]
1393 // If the "o" value is 0 (i.e., _target is nullptr), the offset is stored
1394 // in the code stream. See internal_word_Relocation::target().
1395 // If _section is not -1, it is appended to the low bits of the offset.
1396 void pack_data_to(CodeSection* dest) override;
1397 void unpack_data() override;
1398
1399 void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest) override;
1400 address target(); // if _target==nullptr, fetch addr from code stream
1401 int section() { return _section; }
1402 address value() override { return target(); }
1403 };
1404
1405 class section_word_Relocation : public internal_word_Relocation {
1406 public:
1407 static RelocationHolder spec(address target, int section) {
1408 return RelocationHolder::construct<section_word_Relocation>(target, section);
1409 }
1410
1411 void copy_into(RelocationHolder& holder) const override;
1412
1413 section_word_Relocation(address target, int section)
1414 : internal_word_Relocation(target, section, relocInfo::section_word_type) {
1415 assert(target != nullptr, "must not be null");
1416 assert(section >= 0 && section < RelocIterator::SECT_LIMIT, "must be a valid section");
1417 }
1418
1419 //void pack_data_to -- inherited
1420 void unpack_data() override;
1421
1422 private:
1423 friend class RelocationHolder;
1424 section_word_Relocation() : internal_word_Relocation(relocInfo::section_word_type) { }
1425 };
1426
1427
1428 class poll_Relocation : public Relocation {
1429 bool is_data() override { return true; }
1430 void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest) override;
1431 public:
1432 poll_Relocation(relocInfo::relocType type = relocInfo::poll_type) : Relocation(type) { }
1433
1434 void copy_into(RelocationHolder& holder) const override;
1435 };
1436
1437 class poll_return_Relocation : public poll_Relocation {
1438 public:
1439 poll_return_Relocation() : poll_Relocation(relocInfo::relocInfo::poll_return_type) { }
1440
1441 void copy_into(RelocationHolder& holder) const override;
1442 };
1443
1444 // We know all the xxx_Relocation classes, so now we can define these:
1445 #define EACH_CASE_AUX(Accessor, Reloc) \
1446 inline Reloc* RelocIterator::Accessor() { \
1447 static const RelocationHolder proto = RelocationHolder::construct<Reloc>(); \
1448 assert(type() == proto.type(), "type must agree"); \
1449 _rh = proto; \
1450 Reloc* r = static_cast<Reloc*>(_rh.reloc()); \
1451 r->set_binding(this); \
1452 r->Reloc::unpack_data(); \
1453 return r; \
1454 }
1455 #define EACH_CASE(name) \
1456 EACH_CASE_AUX(PASTE_TOKENS(name, _reloc), PASTE_TOKENS(name, _Relocation))
1457 APPLY_TO_RELOCATIONS(EACH_CASE);
1458 #undef EACH_CASE_AUX
1459 #undef EACH_CASE
1460
1461 inline RelocIterator::RelocIterator(nmethod* nm, address begin, address limit) {
1462 initialize(nm, begin, limit);
1463 }
1464
1465 #endif // SHARE_CODE_RELOCINFO_HPP