jdk8-mips64-public/hotspot: src/share/vm/code/relocInfo.hpp@0878d7bae69f (annotated)

src/share/vm/code/relocInfo.hpp@0878d7bae69f (annotated)

src/share/vm/code/relocInfo.hpp

Fri, 27 Aug 2010 01:51:27 -0700

author: twisti
date: Fri, 27 Aug 2010 01:51:27 -0700
changeset 2117: 0878d7bae69f
parent 1934: e9ff18c4ace7
child 2314: f95d63e2154a
permissions: -rw-r--r--

6961697: move nmethod constants section before instruction section
Summary: This is a preparation for 6961690.
Reviewed-by: kvn, never

 /*
  * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 // Types in this file:
 //    relocInfo
 //      One element of an array of halfwords encoding compressed relocations.
 //      Also, the source of relocation types (relocInfo::oop_type, ...).
 //    Relocation
 //      A flyweight object representing a single relocation.
 //      It is fully unpacked from the compressed relocation array.
 //    oop_Relocation, ... (subclasses of Relocation)
 //      The location of some type-specific operations (oop_addr, ...).
 //      Also, the source of relocation specs (oop_Relocation::spec, ...).
 //    RelocationHolder
 //      A ValueObj type which acts as a union holding a Relocation object.
 //      Represents a relocation spec passed into a CodeBuffer during assembly.
 //    RelocIterator
 //      A StackObj which iterates over the relocations associated with
 //      a range of code addresses.  Can be used to operate a copy of code.
 //    PatchingRelocIterator
 //      Specialized subtype of RelocIterator which removes breakpoints
 //      temporarily during iteration, then restores them.
 //    BoundRelocation
 //      An _internal_ type shared by packers and unpackers of relocations.
 //      It pastes together a RelocationHolder with some pointers into
 //      code and relocInfo streams.
 // Notes on relocType:
 //
 // These hold enough information to read or write a value embedded in
 // the instructions of an CodeBlob.  They're used to update:
 //
 //   1) embedded oops     (isOop()          == true)
 //   2) inline caches     (isIC()           == true)
 //   3) runtime calls     (isRuntimeCall()  == true)
 //   4) internal word ref (isInternalWord() == true)
 //   5) external word ref (isExternalWord() == true)
 //
 // when objects move (GC) or if code moves (compacting the code heap).
 // They are also used to patch the code (if a call site must change)
 //
 // A relocInfo is represented in 16 bits:
 //   4 bits indicating the relocation type
 //  12 bits indicating the offset from the previous relocInfo address
 //
 // The offsets accumulate along the relocInfo stream to encode the
 // address within the CodeBlob, which is named RelocIterator::addr().
 // The address of a particular relocInfo always points to the first
 // byte of the relevant instruction (and not to any of its subfields
 // or embedded immediate constants).
 //
 // The offset value is scaled appropriately for the target machine.
 // (See relocInfo_<arch>.hpp for the offset scaling.)
 //
 // On some machines, there may also be a "format" field which may provide
 // additional information about the format of the instruction stream
 // at the corresponding code address.  The format value is usually zero.
 // Any machine (such as Intel) whose instructions can sometimes contain
 // more than one relocatable constant needs format codes to distinguish
 // which operand goes with a given relocation.
 //
 // If the target machine needs N format bits, the offset has 12-N bits,
 // the format is encoded between the offset and the type, and the
 // relocInfo_<arch>.hpp file has manifest constants for the format codes.
 //
 // If the type is "data_prefix_tag" then the offset bits are further encoded,
 // and in fact represent not a code-stream offset but some inline data.
 // The data takes the form of a counted sequence of halfwords, which
 // precedes the actual relocation record.  (Clients never see it directly.)
 // The interpetation of this extra data depends on the relocation type.
 //
 // On machines that have 32-bit immediate fields, there is usually
 // little need for relocation "prefix" data, because the instruction stream
 // is a perfectly reasonable place to store the value.  On machines in
 // which 32-bit values must be "split" across instructions, the relocation
 // data is the "true" specification of the value, which is then applied
 // to some field of the instruction (22 or 13 bits, on SPARC).
 //
 // Whenever the location of the CodeBlob changes, any PC-relative
 // relocations, and any internal_word_type relocations, must be reapplied.
 // After the GC runs, oop_type relocations must be reapplied.
 //
 //
 // Here are meanings of the types:
 //
 // relocInfo::none -- a filler record
 //   Value:  none
 //   Instruction: The corresponding code address is ignored
 //   Data:  Any data prefix and format code are ignored
 //   (This means that any relocInfo can be disabled by setting
 //   its type to none.  See relocInfo::remove.)
 //
 // relocInfo::oop_type -- a reference to an oop
 //   Value:  an oop, or else the address (handle) of an oop
 //   Instruction types: memory (load), set (load address)
 //   Data:  []       an oop stored in 4 bytes of instruction
 //          [n]      n is the index of an oop in the CodeBlob's oop pool
 //          [[N]n l] and l is a byte offset to be applied to the oop
 //          [Nn Ll]  both index and offset may be 32 bits if necessary
 //   Here is a special hack, used only by the old compiler:
 //          [[N]n 00] the value is the __address__ of the nth oop in the pool
 //   (Note that the offset allows optimal references to class variables.)
 //
 // relocInfo::internal_word_type -- an address within the same CodeBlob
 // relocInfo::section_word_type -- same, but can refer to another section
 //   Value:  an address in the CodeBlob's code or constants section
 //   Instruction types: memory (load), set (load address)
 //   Data:  []     stored in 4 bytes of instruction
 //          [[L]l] a relative offset (see [About Offsets] below)
 //   In the case of section_word_type, the offset is relative to a section
 //   base address, and the section number (e.g., SECT_INSTS) is encoded
 //   into the low two bits of the offset L.
 //
 // relocInfo::external_word_type -- a fixed address in the runtime system
 //   Value:  an address
 //   Instruction types: memory (load), set (load address)
 //   Data:  []   stored in 4 bytes of instruction
 //          [n]  the index of a "well-known" stub (usual case on RISC)
 //          [Ll] a 32-bit address
 //
 // relocInfo::runtime_call_type -- a fixed subroutine in the runtime system
 //   Value:  an address
 //   Instruction types: PC-relative call (or a PC-relative branch)
 //   Data:  []   stored in 4 bytes of instruction
 //
 // relocInfo::static_call_type -- a static call
 //   Value:  an CodeBlob, a stub, or a fixup routine
 //   Instruction types: a call
 //   Data:  []
 //   The identity of the callee is extracted from debugging information.
 //   //%note reloc_3
 //
 // relocInfo::virtual_call_type -- a virtual call site (which includes an inline
 //                                 cache)
 //   Value:  an CodeBlob, a stub, the interpreter, or a fixup routine
 //   Instruction types: a call, plus some associated set-oop instructions
 //   Data:  []       the associated set-oops are adjacent to the call
 //          [n]      n is a relative offset to the first set-oop
 //          [[N]n l] and l is a limit within which the set-oops occur
 //          [Nn Ll]  both n and l may be 32 bits if necessary
 //   The identity of the callee is extracted from debugging information.
 //
 // relocInfo::opt_virtual_call_type -- a virtual call site that is statically bound
 //
 //    Same info as a static_call_type. We use a special type, so the handling of
 //    virtuals and statics are separated.
 //
 //
 //   The offset n points to the first set-oop.  (See [About Offsets] below.)
 //   In turn, the set-oop instruction specifies or contains an oop cell devoted
 //   exclusively to the IC call, which can be patched along with the call.
 //
 //   The locations of any other set-oops are found by searching the relocation
 //   information starting at the first set-oop, and continuing until all
 //   relocations up through l have been inspected.  The value l is another
 //   relative offset.  (Both n and l are relative to the call's first byte.)
 //
 //   The limit l of the search is exclusive.  However, if it points within
 //   the call (e.g., offset zero), it is adjusted to point after the call and
 //   any associated machine-specific delay slot.
 //
 //   Since the offsets could be as wide as 32-bits, these conventions
 //   put no restrictions whatever upon code reorganization.
 //
 //   The compiler is responsible for ensuring that transition from a clean
 //   state to a monomorphic compiled state is MP-safe.  This implies that
 //   the system must respond well to intermediate states where a random
 //   subset of the set-oops has been correctly from the clean state
 //   upon entry to the VEP of the compiled method.  In the case of a
 //   machine (Intel) with a single set-oop instruction, the 32-bit
 //   immediate field must not straddle a unit of memory coherence.
 //   //%note reloc_3
 //
 // relocInfo::breakpoint_type -- a conditional breakpoint in the code
 //   Value:  none
 //   Instruction types: any whatsoever
 //   Data:  [b [T]t  i...]
 //   The b is a bit-packed word representing the breakpoint's attributes.
 //   The t is a target address which the breakpoint calls (when it is enabled).
 //   The i... is a place to store one or two instruction words overwritten
 //   by a trap, so that the breakpoint may be subsequently removed.
 //
 // relocInfo::static_stub_type -- an extra stub for each static_call_type
 //   Value:  none
 //   Instruction types: a virtual call:  { set_oop; jump; }
 //   Data:  [[N]n]  the offset of the associated static_call reloc
 //   This stub becomes the target of a static call which must be upgraded
 //   to a virtual call (because the callee is interpreted).
 //   See [About Offsets] below.
 //   //%note reloc_2
 //
 // For example:
 //
 //   INSTRUCTIONS                        RELOC: TYPE    PREFIX DATA
 //   ------------                               ----    -----------
 // sethi      %hi(myObject),  R               oop_type [n(myObject)]
 // ld      [R+%lo(myObject)+fldOffset], R2    oop_type [n(myObject) fldOffset]
 // add R2, 1, R2
 // st  R2, [R+%lo(myObject)+fldOffset]        oop_type [n(myObject) fldOffset]
 //%note reloc_1
 //
 // This uses 4 instruction words, 8 relocation halfwords,
 // and an entry (which is sharable) in the CodeBlob's oop pool,
 // for a total of 36 bytes.
 //
 // Note that the compiler is responsible for ensuring the "fldOffset" when
 // added to "%lo(myObject)" does not overflow the immediate fields of the
 // memory instructions.
 //
 //
 // [About Offsets] Relative offsets are supplied to this module as
 // positive byte offsets, but they may be internally stored scaled
 // and/or negated, depending on what is most compact for the target
 // system.  Since the object pointed to by the offset typically
 // precedes the relocation address, it is profitable to store
 // these negative offsets as positive numbers, but this decision
 // is internal to the relocation information abstractions.
 //
 class Relocation;
 class CodeBuffer;
 class CodeSection;
 class RelocIterator;
 class relocInfo VALUE_OBJ_CLASS_SPEC {
   friend class RelocIterator;
  public:
   enum relocType {
     none                    =  0, // Used when no relocation should be generated
     oop_type                =  1, // embedded oop
     virtual_call_type       =  2, // a standard inline cache call for a virtual send
     opt_virtual_call_type   =  3, // a virtual call that has been statically bound (i.e., no IC cache)
     static_call_type        =  4, // a static send
     static_stub_type        =  5, // stub-entry for static send  (takes care of interpreter case)
     runtime_call_type       =  6, // call to fixed external routine
     external_word_type      =  7, // reference to fixed external address
     internal_word_type      =  8, // reference within the current code blob
     section_word_type       =  9, // internal, but a cross-section reference
     poll_type               = 10, // polling instruction for safepoints
     poll_return_type        = 11, // polling instruction for safepoints at return
     breakpoint_type         = 12, // an initialization barrier or safepoint
     yet_unused_type         = 13, // Still unused
     yet_unused_type_2       = 14, // Still unused
     data_prefix_tag         = 15, // tag for a prefix (carries data arguments)
     type_mask               = 15  // A mask which selects only the above values
   };
  protected:
   unsigned short _value;
   enum RawBitsToken { RAW_BITS };
   relocInfo(relocType type, RawBitsToken ignore, int bits)
     : _value((type << nontype_width) + bits) { }
   relocInfo(relocType type, RawBitsToken ignore, int off, int f)
     : _value((type << nontype_width) + (off / (unsigned)offset_unit) + (f << offset_width)) { }
  public:
   // constructor
   relocInfo(relocType type, int offset, int format = 0)
 #ifndef ASSERT
   {
     (*this) = relocInfo(type, RAW_BITS, offset, format);
   }
 #else
   // Put a bunch of assertions out-of-line.
   ;
 #endif
   #define APPLY_TO_RELOCATIONS(visitor) \
     visitor(oop) \
     visitor(virtual_call) \
     visitor(opt_virtual_call) \
     visitor(static_call) \
     visitor(static_stub) \
     visitor(runtime_call) \
     visitor(external_word) \
     visitor(internal_word) \
     visitor(poll) \
     visitor(poll_return) \
     visitor(breakpoint) \
     visitor(section_word) \
  public:
   enum {
     value_width             = sizeof(unsigned short) * BitsPerByte,
     type_width              = 4,   // == log2(type_mask+1)
     nontype_width           = value_width - type_width,
     datalen_width           = nontype_width-1,
     datalen_tag             = 1 << datalen_width,  // or-ed into _value
     datalen_limit           = 1 << datalen_width,
     datalen_mask            = (1 << datalen_width)-1
   };
   // accessors
  public:
   relocType  type()       const { return (relocType)((unsigned)_value >> nontype_width); }
   int  format()           const { return format_mask==0? 0: format_mask &
                                          ((unsigned)_value >> offset_width); }
   int  addr_offset()      const { assert(!is_prefix(), "must have offset");
                                   return (_value & offset_mask)*offset_unit; }
  protected:
   const short* data()     const { assert(is_datalen(), "must have data");
                                   return (const short*)(this + 1); }
   int          datalen()  const { assert(is_datalen(), "must have data");
                                   return (_value & datalen_mask); }
   int         immediate() const { assert(is_immediate(), "must have immed");
                                   return (_value & datalen_mask); }
  public:
   static int addr_unit()        { return offset_unit; }
   static int offset_limit()     { return (1 << offset_width) * offset_unit; }
   void set_type(relocType type);
   void set_format(int format);
   void remove() { set_type(none); }
  protected:
   bool is_none()                const { return type() == none; }
   bool is_prefix()              const { return type() == data_prefix_tag; }
   bool is_datalen()             const { assert(is_prefix(), "must be prefix");
                                         return (_value & datalen_tag) != 0; }
   bool is_immediate()           const { assert(is_prefix(), "must be prefix");
                                         return (_value & datalen_tag) == 0; }
  public:
   // Occasionally records of type relocInfo::none will appear in the stream.
   // We do not bother to filter these out, but clients should ignore them.
   // These records serve as "filler" in three ways:
   //  - to skip large spans of unrelocated code (this is rare)
   //  - to pad out the relocInfo array to the required oop alignment
   //  - to disable old relocation information which is no longer applicable
   inline friend relocInfo filler_relocInfo();
   // Every non-prefix relocation may be preceded by at most one prefix,
   // which supplies 1 or more halfwords of associated data.  Conventionally,
   // an int is represented by 0, 1, or 2 halfwords, depending on how
   // many bits are required to represent the value.  (In addition,
   // if the sole halfword is a 10-bit unsigned number, it is made
   // "immediate" in the prefix header word itself.  This optimization
   // is invisible outside this module.)
   inline friend relocInfo prefix_relocInfo(int datalen = 0);
  protected:
   // an immediate relocInfo optimizes a prefix with one 10-bit unsigned value
   static relocInfo immediate_relocInfo(int data0) {
     assert(fits_into_immediate(data0), "data0 in limits");
     return relocInfo(relocInfo::data_prefix_tag, RAW_BITS, data0);
   }
   static bool fits_into_immediate(int data0) {
     return (data0 >= 0 && data0 < datalen_limit);
   }
  public:
   // Support routines for compilers.
   // This routine takes an infant relocInfo (unprefixed) and
   // edits in its prefix, if any.  It also updates dest.locs_end.
   void initialize(CodeSection* dest, Relocation* reloc);
   // This routine updates a prefix and returns the limit pointer.
   // It tries to compress the prefix from 32 to 16 bits, and if
   // successful returns a reduced "prefix_limit" pointer.
   relocInfo* finish_prefix(short* prefix_limit);
   // bit-packers for the data array:
   // As it happens, the bytes within the shorts are ordered natively,
   // but the shorts within the word are ordered big-endian.
   // This is an arbitrary choice, made this way mainly to ease debugging.
   static int data0_from_int(jint x)         { return x >> value_width; }
   static int data1_from_int(jint x)         { return (short)x; }
   static jint jint_from_data(short* data) {
     return (data[0] << value_width) + (unsigned short)data[1];
   }
   static jint short_data_at(int n, short* data, int datalen) {
     return datalen > n ? data[n] : 0;
   }
   static jint jint_data_at(int n, short* data, int datalen) {
     return datalen > n+1 ? jint_from_data(&data[n]) : short_data_at(n, data, datalen);
   }
   // Update methods for relocation information
   // (since code is dynamically patched, we also need to dynamically update the relocation info)
   // Both methods takes old_type, so it is able to performe sanity checks on the information removed.
   static void change_reloc_info_for_address(RelocIterator *itr, address pc, relocType old_type, relocType new_type);
   static void remove_reloc_info_for_address(RelocIterator *itr, address pc, relocType old_type);
   // Machine dependent stuff
   #include "incls/_relocInfo_pd.hpp.incl"
  protected:
   // Derived constant, based on format_width which is PD:
   enum {
     offset_width       = nontype_width - format_width,
     offset_mask        = (1<<offset_width) - 1,
     format_mask        = (1<<format_width) - 1
   };
  public:
   enum {
     // Conservatively large estimate of maximum length (in shorts)
     // of any relocation record (probably breakpoints are largest).
     // Extended format is length prefix, data words, and tag/offset suffix.
     length_limit       = 1 + 1 + (3*BytesPerWord/BytesPerShort) + 1,
     have_format        = format_width > 0
   };
 };
 #define FORWARD_DECLARE_EACH_CLASS(name)              \
 class name##_Relocation;
 APPLY_TO_RELOCATIONS(FORWARD_DECLARE_EACH_CLASS)
 #undef FORWARD_DECLARE_EACH_CLASS
 inline relocInfo filler_relocInfo() {
   return relocInfo(relocInfo::none, relocInfo::offset_limit() - relocInfo::offset_unit);
 }
 inline relocInfo prefix_relocInfo(int datalen) {
   assert(relocInfo::fits_into_immediate(datalen), "datalen in limits");
   return relocInfo(relocInfo::data_prefix_tag, relocInfo::RAW_BITS, relocInfo::datalen_tag | datalen);
 }
 // Holder for flyweight relocation objects.
 // Although the flyweight subclasses are of varying sizes,
 // the holder is "one size fits all".
 class RelocationHolder VALUE_OBJ_CLASS_SPEC {
   friend class Relocation;
   friend class CodeSection;
  private:
   // this preallocated memory must accommodate all subclasses of Relocation
   // (this number is assertion-checked in Relocation::operator new)
   enum { _relocbuf_size = 5 };
   void* _relocbuf[ _relocbuf_size ];
  public:
   Relocation* reloc() const { return (Relocation*) &_relocbuf[0]; }
   inline relocInfo::relocType type() const;
   // Add a constant offset to a relocation.  Helper for class Address.
   RelocationHolder plus(int offset) const;
   inline RelocationHolder();                // initializes type to none
   inline RelocationHolder(Relocation* r);   // make a copy
   static const RelocationHolder none;
 };
 // A RelocIterator iterates through the relocation information of a CodeBlob.
 // It is a variable BoundRelocation which is able to take on successive
 // values as it is advanced through a code stream.
 // Usage:
 //   RelocIterator iter(nm);
 //   while (iter.next()) {
 //     iter.reloc()->some_operation();
 //   }
 // or:
 //   RelocIterator iter(nm);
 //   while (iter.next()) {
 //     switch (iter.type()) {
 //      case relocInfo::oop_type          :
 //      case relocInfo::ic_type           :
 //      case relocInfo::prim_type         :
 //      case relocInfo::uncommon_type     :
 //      case relocInfo::runtime_call_type :
 //      case relocInfo::internal_word_type:
 //      case relocInfo::external_word_type:
 //      ...
 //     }
 //   }
 class RelocIterator : public StackObj {
   enum { SECT_LIMIT = 3 };  // must be equal to CodeBuffer::SECT_LIMIT, checked in ctor
   friend class Relocation;
   friend class relocInfo;       // for change_reloc_info_for_address only
   typedef relocInfo::relocType relocType;
  private:
   address    _limit;   // stop producing relocations after this _addr
   relocInfo* _current; // the current relocation information
   relocInfo* _end;     // end marker; we're done iterating when _current == _end
   nmethod*   _code;    // compiled method containing _addr
   address    _addr;    // instruction to which the relocation applies
   short      _databuf; // spare buffer for compressed data
   short*     _data;    // pointer to the relocation's data
   short      _datalen; // number of halfwords in _data
   char       _format;  // position within the instruction
   // Base addresses needed to compute targets of section_word_type relocs.
   address    _section_start[SECT_LIMIT];
   address    _section_end  [SECT_LIMIT];
   void set_has_current(bool b) {
     _datalen = !b ? -1 : 0;
     debug_only(_data = NULL);
   }
   void set_current(relocInfo& ri) {
     _current = &ri;
     set_has_current(true);
   }
   RelocationHolder _rh; // where the current relocation is allocated
   relocInfo* current() const { assert(has_current(), "must have current");
                                return _current; }
   void set_limits(address begin, address limit);
   void advance_over_prefix();    // helper method
   void initialize_misc();
   void initialize(nmethod* nm, address begin, address limit);
   friend class PatchingRelocIterator;
   // make an uninitialized one, for PatchingRelocIterator:
   RelocIterator() { initialize_misc(); }
  public:
   // constructor
   RelocIterator(nmethod* nm,     address begin = NULL, address limit = NULL);
   RelocIterator(CodeSection* cb, address begin = NULL, address limit = NULL);
   // get next reloc info, return !eos
   bool next() {
     _current++;
     assert(_current <= _end, "must not overrun relocInfo");
     if (_current == _end) {
       set_has_current(false);
       return false;
     }
     set_has_current(true);
     if (_current->is_prefix()) {
       advance_over_prefix();
       assert(!current()->is_prefix(), "only one prefix at a time");
     }
     _addr += _current->addr_offset();
     if (_limit != NULL && _addr >= _limit) {
       set_has_current(false);
       return false;
     }
     if (relocInfo::have_format)  _format = current()->format();
     return true;
   }
   // accessors
   address      limit()        const { return _limit; }
   void     set_limit(address x);
   relocType    type()         const { return current()->type(); }
   int          format()       const { return (relocInfo::have_format) ? current()->format() : 0; }
   address      addr()         const { return _addr; }
   nmethod*     code()         const { return _code; }
   short*       data()         const { return _data; }
   int          datalen()      const { return _datalen; }
   bool     has_current()      const { return _datalen >= 0; }
   void       set_addr(address addr) { _addr = addr; }
   bool   addr_in_const()      const;
   address section_start(int n) const {
     assert(_section_start[n], "must be initialized");
     return _section_start[n];
   }
   address section_end(int n) const {
     assert(_section_end[n], "must be initialized");
     return _section_end[n];
   }
   // The address points to the affected displacement part of the instruction.
   // For RISC, this is just the whole instruction.
   // For Intel, this is an unaligned 32-bit word.
   // type-specific relocation accessors:  oop_Relocation* oop_reloc(), etc.
   #define EACH_TYPE(name)                               \
   inline name##_Relocation* name##_reloc();
   APPLY_TO_RELOCATIONS(EACH_TYPE)
   #undef EACH_TYPE
   // generic relocation accessor; switches on type to call the above
   Relocation* reloc();
   // CodeBlob's have relocation indexes for faster random access:
   static int locs_and_index_size(int code_size, int locs_size);
   // Store an index into [dest_start+dest_count..dest_end).
   // At dest_start[0..dest_count] is the actual relocation information.
   // Everything else up to dest_end is free space for the index.
   static void create_index(relocInfo* dest_begin, int dest_count, relocInfo* dest_end);
 #ifndef PRODUCT
  public:
   void print();
   void print_current();
 #endif
 };
 // A Relocation is a flyweight object allocated within a RelocationHolder.
 // It represents the relocation data of relocation record.
 // So, the RelocIterator unpacks relocInfos into Relocations.
 class Relocation VALUE_OBJ_CLASS_SPEC {
   friend class RelocationHolder;
   friend class RelocIterator;
  private:
   static void guarantee_size();
   // When a relocation has been created by a RelocIterator,
   // this field is non-null.  It allows the relocation to know
   // its context, such as the address to which it applies.
   RelocIterator* _binding;
  protected:
   RelocIterator* binding() const {
     assert(_binding != NULL, "must be bound");
     return _binding;
   }
   void set_binding(RelocIterator* b) {
     assert(_binding == NULL, "must be unbound");
     _binding = b;
     assert(_binding != NULL, "must now be bound");
   }
   Relocation() {
     _binding = NULL;
   }
   static RelocationHolder newHolder() {
     return RelocationHolder();
   }
  public:
   void* operator new(size_t size, const RelocationHolder& holder) {
     if (size > sizeof(holder._relocbuf)) guarantee_size();
     assert((void* const *)holder.reloc() == &holder._relocbuf[0], "ptrs must agree");
     return holder.reloc();
   }
   // make a generic relocation for a given type (if possible)
   static RelocationHolder spec_simple(relocInfo::relocType rtype);
   // here is the type-specific hook which writes relocation data:
   virtual void pack_data_to(CodeSection* dest) { }
   // here is the type-specific hook which reads (unpacks) relocation data:
   virtual void unpack_data() {
     assert(datalen()==0 || type()==relocInfo::none, "no data here");
   }
  protected:
   // Helper functions for pack_data_to() and unpack_data().
   // Most of the compression logic is confined here.
   // (The "immediate data" mechanism of relocInfo works independently
   // of this stuff, and acts to further compress most 1-word data prefixes.)
   // A variable-width int is encoded as a short if it will fit in 16 bits.
   // The decoder looks at datalen to decide whether to unpack short or jint.
   // Most relocation records are quite simple, containing at most two ints.
   static bool is_short(jint x) { return x == (short)x; }
   static short* add_short(short* p, int x)  { *p++ = x; return p; }
   static short* add_jint (short* p, jint x) {
     *p++ = relocInfo::data0_from_int(x); *p++ = relocInfo::data1_from_int(x);
     return p;
   }
   static short* add_var_int(short* p, jint x) {   // add a variable-width int
     if (is_short(x))  p = add_short(p, x);
     else              p = add_jint (p, x);
     return p;
   }
   static short* pack_1_int_to(short* p, jint x0) {
     // Format is one of:  [] [x] [Xx]
     if (x0 != 0)  p = add_var_int(p, x0);
     return p;
   }
   int unpack_1_int() {
     assert(datalen() <= 2, "too much data");
     return relocInfo::jint_data_at(0, data(), datalen());
   }
   // With two ints, the short form is used only if both ints are short.
   short* pack_2_ints_to(short* p, jint x0, jint x1) {
     // Format is one of:  [] [x y?] [Xx Y?y]
     if (x0 == 0 && x1 == 0) {
       // no halfwords needed to store zeroes
     } else if (is_short(x0) && is_short(x1)) {
       // 1-2 halfwords needed to store shorts
       p = add_short(p, x0); if (x1!=0) p = add_short(p, x1);
     } else {
       // 3-4 halfwords needed to store jints
       p = add_jint(p, x0);             p = add_var_int(p, x1);
     }
     return p;
   }
   void unpack_2_ints(jint& x0, jint& x1) {
     int    dlen = datalen();
     short* dp  = data();
     if (dlen <= 2) {
       x0 = relocInfo::short_data_at(0, dp, dlen);
       x1 = relocInfo::short_data_at(1, dp, dlen);
     } else {
       assert(dlen <= 4, "too much data");
       x0 = relocInfo::jint_data_at(0, dp, dlen);
       x1 = relocInfo::jint_data_at(2, dp, dlen);
     }
   }
  protected:
   // platform-dependent utilities for decoding and patching instructions
   void       pd_set_data_value       (address x, intptr_t off); // a set or mem-ref
   address    pd_call_destination     (address orig_addr = NULL);
   void       pd_set_call_destination (address x);
   void       pd_swap_in_breakpoint   (address x, short* instrs, int instrlen);
   void       pd_swap_out_breakpoint  (address x, short* instrs, int instrlen);
   static int pd_breakpoint_size      ();
   // this extracts the address of an address in the code stream instead of the reloc data
   address* pd_address_in_code       ();
   // this extracts an address from the code stream instead of the reloc data
   address  pd_get_address_from_code ();
   // these convert from byte offsets, to scaled offsets, to addresses
   static jint scaled_offset(address x, address base) {
     int byte_offset = x - base;
     int offset = -byte_offset / relocInfo::addr_unit();
     assert(address_from_scaled_offset(offset, base) == x, "just checkin'");
     return offset;
   }
   static jint scaled_offset_null_special(address x, address base) {
     // Some relocations treat offset=0 as meaning NULL.
     // Handle this extra convention carefully.
     if (x == NULL)  return 0;
     assert(x != base, "offset must not be zero");
     return scaled_offset(x, base);
   }
   static address address_from_scaled_offset(jint offset, address base) {
     int byte_offset = -( offset * relocInfo::addr_unit() );
     return base + byte_offset;
   }
   // these convert between indexes and addresses in the runtime system
   static int32_t runtime_address_to_index(address runtime_address);
   static address index_to_runtime_address(int32_t index);
   // helpers for mapping between old and new addresses after a move or resize
   address old_addr_for(address newa, const CodeBuffer* src, CodeBuffer* dest);
   address new_addr_for(address olda, const CodeBuffer* src, CodeBuffer* dest);
   void normalize_address(address& addr, const CodeSection* dest, bool allow_other_sections = false);
  public:
   // accessors which only make sense for a bound Relocation
   address  addr()         const { return binding()->addr(); }
   nmethod* code()         const { return binding()->code(); }
   bool     addr_in_const() const { return binding()->addr_in_const(); }
  protected:
   short*   data()         const { return binding()->data(); }
   int      datalen()      const { return binding()->datalen(); }
   int      format()       const { return binding()->format(); }
  public:
   virtual relocInfo::relocType type()            { return relocInfo::none; }
   // is it a call instruction?
   virtual bool is_call()                         { return false; }
   // is it a data movement instruction?
   virtual bool is_data()                         { return false; }
   // some relocations can compute their own values
   virtual address  value();
   // all relocations are able to reassert their values
   virtual void set_value(address x);
   virtual void clear_inline_cache()              { }
   // This method assumes that all virtual/static (inline) caches are cleared (since for static_call_type and
   // ic_call_type is not always posisition dependent (depending on the state of the cache)). However, this is
   // probably a reasonable assumption, since empty caches simplifies code reloacation.
   virtual void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest) { }
   void print();
 };
 // certain inlines must be deferred until class Relocation is defined:
 inline RelocationHolder::RelocationHolder() {
   // initialize the vtbl, just to keep things type-safe
   new(*this) Relocation();
 }
 inline RelocationHolder::RelocationHolder(Relocation* r) {
   // wordwise copy from r (ok if it copies garbage after r)
   for (int i = 0; i < _relocbuf_size; i++) {
     _relocbuf[i] = ((void**)r)[i];
   }
 }
 relocInfo::relocType RelocationHolder::type() const {
   return reloc()->type();
 }
 // A DataRelocation always points at a memory or load-constant instruction..
 // It is absolute on most machines, and the constant is split on RISCs.
 // The specific subtypes are oop, external_word, and internal_word.
 // By convention, the "value" does not include a separately reckoned "offset".
 class DataRelocation : public Relocation {
  public:
   bool          is_data()                      { return true; }
   // both target and offset must be computed somehow from relocation data
   virtual int    offset()                      { return 0; }
   address         value()                      = 0;
   void        set_value(address x)             { set_value(x, offset()); }
   void        set_value(address x, intptr_t o) {
     if (addr_in_const())
       *(address*)addr() = x;
     else
       pd_set_data_value(x, o);
   }
   // The "o" (displacement) argument is relevant only to split relocations
   // on RISC machines.  In some CPUs (SPARC), the set-hi and set-lo ins'ns
   // can encode more than 32 bits between them.  This allows compilers to
   // share set-hi instructions between addresses that differ by a small
   // offset (e.g., different static variables in the same class).
   // On such machines, the "x" argument to set_value on all set-lo
   // instructions must be the same as the "x" argument for the
   // corresponding set-hi instructions.  The "o" arguments for the
   // set-hi instructions are ignored, and must not affect the high-half
   // immediate constant.  The "o" arguments for the set-lo instructions are
   // added into the low-half immediate constant, and must not overflow it.
 };
 // A CallRelocation always points at a call instruction.
 // It is PC-relative on most machines.
 class CallRelocation : public Relocation {
  public:
   bool is_call() { return true; }
   address  destination()                    { return pd_call_destination(); }
   void     set_destination(address x); // pd_set_call_destination
   void     fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest);
   address  value()                          { return destination();  }
   void     set_value(address x)             { set_destination(x); }
 };
 class oop_Relocation : public DataRelocation {
   relocInfo::relocType type() { return relocInfo::oop_type; }
  public:
   // encode in one of these formats:  [] [n] [n l] [Nn l] [Nn Ll]
   // an oop in the CodeBlob's oop pool
   static RelocationHolder spec(int oop_index, int offset = 0) {
     assert(oop_index > 0, "must be a pool-resident oop");
     RelocationHolder rh = newHolder();
     new(rh) oop_Relocation(oop_index, offset);
     return rh;
   }
   // an oop in the instruction stream
   static RelocationHolder spec_for_immediate() {
     const int oop_index = 0;
     const int offset    = 0;    // if you want an offset, use the oop pool
     RelocationHolder rh = newHolder();
     new(rh) oop_Relocation(oop_index, offset);
     return rh;
   }
  private:
   jint _oop_index;                  // if > 0, index into CodeBlob::oop_at
   jint _offset;                     // byte offset to apply to the oop itself
   oop_Relocation(int oop_index, int offset) {
     _oop_index = oop_index; _offset = offset;
   }
   friend class RelocIterator;
   oop_Relocation() { }
  public:
   int oop_index() { return _oop_index; }
   int offset()    { return _offset; }
   // data is packed in "2_ints" format:  [i o] or [Ii Oo]
   void pack_data_to(CodeSection* dest);
   void unpack_data();
   void fix_oop_relocation();        // reasserts oop value
   address value()  { return (address) *oop_addr(); }
   bool oop_is_immediate()  { return oop_index() == 0; }
   oop* oop_addr();                  // addr or &pool[jint_data]
   oop  oop_value();                 // *oop_addr
   // Note:  oop_value transparently converts Universe::non_oop_word to NULL.
 };
 class virtual_call_Relocation : public CallRelocation {
   relocInfo::relocType type() { return relocInfo::virtual_call_type; }
  public:
   // "first_oop" points to the first associated set-oop.
   // The oop_limit helps find the last associated set-oop.
   // (See comments at the top of this file.)
   static RelocationHolder spec(address first_oop, address oop_limit = NULL) {
     RelocationHolder rh = newHolder();
     new(rh) virtual_call_Relocation(first_oop, oop_limit);
     return rh;
   }
   virtual_call_Relocation(address first_oop, address oop_limit) {
     _first_oop = first_oop; _oop_limit = oop_limit;
     assert(first_oop != NULL, "first oop address must be specified");
   }
  private:
   address _first_oop;               // location of first set-oop instruction
   address _oop_limit;               // search limit for set-oop instructions
   friend class RelocIterator;
   virtual_call_Relocation() { }
  public:
   address first_oop();
   address oop_limit();
   // data is packed as scaled offsets in "2_ints" format:  [f l] or [Ff Ll]
   // oop_limit is set to 0 if the limit falls somewhere within the call.
   // When unpacking, a zero oop_limit is taken to refer to the end of the call.
   // (This has the effect of bringing in the call's delay slot on SPARC.)
   void pack_data_to(CodeSection* dest);
   void unpack_data();
   void clear_inline_cache();
   // Figure out where an ic_call is hiding, given a set-oop or call.
   // Either ic_call or first_oop must be non-null; the other is deduced.
   // Code if non-NULL must be the nmethod, else it is deduced.
   // The address of the patchable oop is also deduced.
   // The returned iterator will enumerate over the oops and the ic_call,
   // as well as any other relocations that happen to be in that span of code.
   // Recognize relevant set_oops with:  oop_reloc()->oop_addr() == oop_addr.
   static RelocIterator parse_ic(nmethod* &nm, address &ic_call, address &first_oop, oop* &oop_addr, bool *is_optimized);
 };
 class opt_virtual_call_Relocation : public CallRelocation {
   relocInfo::relocType type() { return relocInfo::opt_virtual_call_type; }
  public:
   static RelocationHolder spec() {
     RelocationHolder rh = newHolder();
     new(rh) opt_virtual_call_Relocation();
     return rh;
   }
  private:
   friend class RelocIterator;
   opt_virtual_call_Relocation() { }
  public:
   void clear_inline_cache();
   // find the matching static_stub
   address static_stub();
 };
 class static_call_Relocation : public CallRelocation {
   relocInfo::relocType type() { return relocInfo::static_call_type; }
  public:
   static RelocationHolder spec() {
     RelocationHolder rh = newHolder();
     new(rh) static_call_Relocation();
     return rh;
   }
  private:
   friend class RelocIterator;
   static_call_Relocation() { }
  public:
   void clear_inline_cache();
   // find the matching static_stub
   address static_stub();
 };
 class static_stub_Relocation : public Relocation {
   relocInfo::relocType type() { return relocInfo::static_stub_type; }
  public:
   static RelocationHolder spec(address static_call) {
     RelocationHolder rh = newHolder();
     new(rh) static_stub_Relocation(static_call);
     return rh;
   }
  private:
   address _static_call;             // location of corresponding static_call
   static_stub_Relocation(address static_call) {
     _static_call = static_call;
   }
   friend class RelocIterator;
   static_stub_Relocation() { }
  public:
   void clear_inline_cache();
   address static_call() { return _static_call; }
   // data is packed as a scaled offset in "1_int" format:  [c] or [Cc]
   void pack_data_to(CodeSection* dest);
   void unpack_data();
 };
 class runtime_call_Relocation : public CallRelocation {
   relocInfo::relocType type() { return relocInfo::runtime_call_type; }
  public:
   static RelocationHolder spec() {
     RelocationHolder rh = newHolder();
     new(rh) runtime_call_Relocation();
     return rh;
   }
  private:
   friend class RelocIterator;
   runtime_call_Relocation() { }
  public:
 };
 class external_word_Relocation : public DataRelocation {
   relocInfo::relocType type() { return relocInfo::external_word_type; }
  public:
   static RelocationHolder spec(address target) {
     assert(target != NULL, "must not be null");
     RelocationHolder rh = newHolder();
     new(rh) external_word_Relocation(target);
     return rh;
   }
   // Use this one where all 32/64 bits of the target live in the code stream.
   // The target must be an intptr_t, and must be absolute (not relative).
   static RelocationHolder spec_for_immediate() {
     RelocationHolder rh = newHolder();
     new(rh) external_word_Relocation(NULL);
     return rh;
   }
  private:
   address _target;                  // address in runtime
   external_word_Relocation(address target) {
     _target = target;
   }
   friend class RelocIterator;
   external_word_Relocation() { }
  public:
   // data is packed as a well-known address in "1_int" format:  [a] or [Aa]
   // The function runtime_address_to_index is used to turn full addresses
   // to short indexes, if they are pre-registered by the stub mechanism.
   // If the "a" value is 0 (i.e., _target is NULL), the address is stored
   // in the code stream.  See external_word_Relocation::target().
   void pack_data_to(CodeSection* dest);
   void unpack_data();
   void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest);
   address  target();        // if _target==NULL, fetch addr from code stream
   address  value()          { return target(); }
 };
 class internal_word_Relocation : public DataRelocation {
   relocInfo::relocType type() { return relocInfo::internal_word_type; }
  public:
   static RelocationHolder spec(address target) {
     assert(target != NULL, "must not be null");
     RelocationHolder rh = newHolder();
     new(rh) internal_word_Relocation(target);
     return rh;
   }
   // use this one where all the bits of the target can fit in the code stream:
   static RelocationHolder spec_for_immediate() {
     RelocationHolder rh = newHolder();
     new(rh) internal_word_Relocation(NULL);
     return rh;
   }
   internal_word_Relocation(address target) {
     _target  = target;
     _section = -1;  // self-relative
   }
  protected:
   address _target;                  // address in CodeBlob
   int     _section;                 // section providing base address, if any
   friend class RelocIterator;
   internal_word_Relocation() { }
   // bit-width of LSB field in packed offset, if section >= 0
   enum { section_width = 2 }; // must equal CodeBuffer::sect_bits
  public:
   // data is packed as a scaled offset in "1_int" format:  [o] or [Oo]
   // If the "o" value is 0 (i.e., _target is NULL), the offset is stored
   // in the code stream.  See internal_word_Relocation::target().
   // If _section is not -1, it is appended to the low bits of the offset.
   void pack_data_to(CodeSection* dest);
   void unpack_data();
   void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest);
   address  target();        // if _target==NULL, fetch addr from code stream
   int      section()        { return _section;   }
   address  value()          { return target();   }
 };
 class section_word_Relocation : public internal_word_Relocation {
   relocInfo::relocType type() { return relocInfo::section_word_type; }
  public:
   static RelocationHolder spec(address target, int section) {
     RelocationHolder rh = newHolder();
     new(rh) section_word_Relocation(target, section);
     return rh;
   }
   section_word_Relocation(address target, int section) {
     assert(target != NULL, "must not be null");
     assert(section >= 0, "must be a valid section");
     _target  = target;
     _section = section;
   }
   //void pack_data_to -- inherited
   void unpack_data();
  private:
   friend class RelocIterator;
   section_word_Relocation() { }
 };
 class poll_Relocation : public Relocation {
   bool          is_data()                      { return true; }
   relocInfo::relocType type() { return relocInfo::poll_type; }
   void     fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest);
 };
 class poll_return_Relocation : public Relocation {
   bool          is_data()                      { return true; }
   relocInfo::relocType type() { return relocInfo::poll_return_type; }
   void     fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest);
 };
 class breakpoint_Relocation : public Relocation {
   relocInfo::relocType type() { return relocInfo::breakpoint_type; }
   enum {
     // attributes which affect the interpretation of the data:
     removable_attr = 0x0010,   // buffer [i...] allows for undoing the trap
     internal_attr  = 0x0020,   // the target is an internal addr (local stub)
     settable_attr  = 0x0040,   // the target is settable
     // states which can change over time:
     enabled_state  = 0x0100,   // breakpoint must be active in running code
     active_state   = 0x0200,   // breakpoint instruction actually in code
     kind_mask      = 0x000F,   // mask for extracting kind
     high_bit       = 0x4000    // extra bit which is always set
   };
  public:
   enum {
     // kinds:
     initialization = 1,
     safepoint      = 2
   };
   // If target is NULL, 32 bits are reserved for a later set_target().
   static RelocationHolder spec(int kind, address target = NULL, bool internal_target = false) {
     RelocationHolder rh = newHolder();
     new(rh) breakpoint_Relocation(kind, target, internal_target);
     return rh;
   }
  private:
   // We require every bits value to NOT to fit into relocInfo::datalen_width,
   // because we are going to actually store state in the reloc, and so
   // cannot allow it to be compressed (and hence copied by the iterator).
   short   _bits;                  // bit-encoded kind, attrs, & state
   address _target;
   breakpoint_Relocation(int kind, address target, bool internal_target);
   friend class RelocIterator;
   breakpoint_Relocation() { }
   short    bits()       const { return _bits; }
   short&   live_bits()  const { return data()[0]; }
   short*   instrs()     const { return data() + datalen() - instrlen(); }
   int      instrlen()   const { return removable() ? pd_breakpoint_size() : 0; }
   void set_bits(short x) {
     assert(live_bits() == _bits, "must be the only mutator of reloc info");
     live_bits() = _bits = x;
   }
  public:
   address  target()     const;
   void set_target(address x);
   int  kind()           const { return  bits() & kind_mask; }
   bool enabled()        const { return (bits() &  enabled_state) != 0; }
   bool active()         const { return (bits() &   active_state) != 0; }
   bool internal()       const { return (bits() &  internal_attr) != 0; }
   bool removable()      const { return (bits() & removable_attr) != 0; }
   bool settable()       const { return (bits() &  settable_attr) != 0; }
   void set_enabled(bool b);     // to activate, you must also say set_active
   void set_active(bool b);      // actually inserts bpt (must be enabled 1st)
   // data is packed as 16 bits, followed by the target (1 or 2 words), followed
   // if necessary by empty storage for saving away original instruction bytes.
   void pack_data_to(CodeSection* dest);
   void unpack_data();
   // during certain operations, breakpoints must be out of the way:
   void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest) {
     assert(!active(), "cannot perform relocation on enabled breakpoints");
   }
 };
 // We know all the xxx_Relocation classes, so now we can define these:
 #define EACH_CASE(name)                                         \
 inline name##_Relocation* RelocIterator::name##_reloc() {       \
   assert(type() == relocInfo::name##_type, "type must agree");  \
   /* The purpose of the placed "new" is to re-use the same */   \
   /* stack storage for each new iteration. */                   \
   name##_Relocation* r = new(_rh) name##_Relocation();          \
   r->set_binding(this);                                         \
   r->name##_Relocation::unpack_data();                          \
   return r;                                                     \
 }
 APPLY_TO_RELOCATIONS(EACH_CASE);
 #undef EACH_CASE
 inline RelocIterator::RelocIterator(nmethod* nm, address begin, address limit) {
   initialize(nm, begin, limit);
 }
 // if you are going to patch code, you should use this subclass of
 // RelocIterator
 class PatchingRelocIterator : public RelocIterator {
  private:
   RelocIterator _init_state;
   void prepass();               // deactivates all breakpoints
   void postpass();              // reactivates all enabled breakpoints
   // do not copy these puppies; it would have unpredictable side effects
   // these are private and have no bodies defined because they should not be called
   PatchingRelocIterator(const RelocIterator&);
   void        operator=(const RelocIterator&);
  public:
   PatchingRelocIterator(nmethod* nm, address begin = NULL, address limit = NULL)
     : RelocIterator(nm, begin, limit)                { prepass();  }
   ~PatchingRelocIterator()                           { postpass(); }
 };

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/code/relocInfo.hpp@0878d7bae69f (annotated)

src/share/vm/code/relocInfo.hpp