src/hotspot/share/asm/codeBuffer.hpp

/*
 * Copyright (c) 1997, 2025, 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.
 *
 */

#ifndef SHARE_ASM_CODEBUFFER_HPP
#define SHARE_ASM_CODEBUFFER_HPP

#include "code/oopRecorder.hpp"
#include "code/relocInfo.hpp"
#include "compiler/compiler_globals.hpp"
#include "runtime/os.hpp"
#include "utilities/align.hpp"
#include "utilities/debug.hpp"
#include "utilities/growableArray.hpp"
#include "utilities/linkedlist.hpp"
#include "utilities/resizeableResourceHash.hpp"
#include "utilities/macros.hpp"

template <typename T>
static inline void put_native(address p, T x) {
    memcpy((void*)p, &x, sizeof x);
}

class PhaseCFG;
class Compile;
class BufferBlob;
class CodeBuffer;
class Label;
class ciMethod;
class SharedStubToInterpRequest;

class CodeOffsets: public StackObj {
public:
  enum Entries { Entry,
                 Verified_Entry,
                 Frame_Complete, // Offset in the code where the frame setup is (for forte stackwalks) is complete
                 OSR_Entry,
                 Exceptions,     // Offset where exception handler lives
                 Deopt,          // Offset where deopt handler lives
                 DeoptMH,        // Offset where MethodHandle deopt handler lives
                 UnwindHandler,  // Offset to default unwind handler
                 max_Entries };

  // special value to note codeBlobs where profile (forte) stack walking is
  // always dangerous and suspect.

  enum { frame_never_safe = -1 };

private:
  int _values[max_Entries];

public:
  CodeOffsets() {
    _values[Entry         ] = 0;
    _values[Verified_Entry] = 0;
    _values[Frame_Complete] = frame_never_safe;
    _values[OSR_Entry     ] = 0;
    _values[Exceptions    ] = -1;
    _values[Deopt         ] = -1;
    _values[DeoptMH       ] = -1;
    _values[UnwindHandler ] = -1;
  }

  int value(Entries e) { return _values[e]; }
  void set_value(Entries e, int val) { _values[e] = val; }
};

// This class represents a stream of code and associated relocations.
// There are a few in each CodeBuffer.
// They are filled concurrently, and concatenated at the end.
class CodeSection {
  friend class CodeBuffer;
  friend class AOTCodeReader;
 public:
  typedef int csize_t;  // code size type; would be size_t except for history

 private:
  address     _start;           // first byte of contents (instructions)
  address     _mark;            // user mark, usually an instruction beginning
  address     _end;             // current end address
  address     _limit;           // last possible (allocated) end address
  relocInfo*  _locs_start;      // first byte of relocation information
  relocInfo*  _locs_end;        // first byte after relocation information
  relocInfo*  _locs_limit;      // first byte after relocation information buf
  address     _locs_point;      // last relocated position (grows upward)
  bool        _locs_own;        // did I allocate the locs myself?
  bool        _scratch_emit;    // Buffer is used for scratch emit, don't relocate.
  int         _skipped_instructions_size;
  int8_t      _index;           // my section number (SECT_INST, etc.)
  CodeBuffer* _outer;           // enclosing CodeBuffer

  // (Note:  _locs_point used to be called _last_reloc_offset.)

  CodeSection() {
    _start         = nullptr;
    _mark          = nullptr;
    _end           = nullptr;
    _limit         = nullptr;
    _locs_start    = nullptr;
    _locs_end      = nullptr;
    _locs_limit    = nullptr;
    _locs_point    = nullptr;
    _locs_own      = false;
    _scratch_emit  = false;
    _skipped_instructions_size = 0;
    DEBUG_ONLY(_index = -1);
    DEBUG_ONLY(_outer = (CodeBuffer*)badAddress);
  }

  void initialize_outer(CodeBuffer* outer, int8_t index) {
    _outer = outer;
    _index = index;
  }

  void initialize(address start, csize_t size = 0) {
    assert(_start == nullptr, "only one init step, please");
    _start         = start;
    _mark          = nullptr;
    _end           = start;

    _limit         = start + size;
    _locs_point    = start;
  }

  void initialize_locs(int locs_capacity);
  void expand_locs(int new_capacity);
  void initialize_locs_from(const CodeSection* source_cs);

  // helper for CodeBuffer::expand()
  void take_over_code_from(CodeSection* cs) {
    _start      = cs->_start;
    _mark       = cs->_mark;
    _end        = cs->_end;
    _limit      = cs->_limit;
    _locs_point = cs->_locs_point;
    _skipped_instructions_size = cs->_skipped_instructions_size;
  }

 public:
  address     start() const         { return _start; }
  address     mark() const          { return _mark; }
  address     end() const           { return _end; }
  address     limit() const         { return _limit; }
  csize_t     size() const          { return (csize_t)(_end - _start); }
  csize_t     mark_off() const      { assert(_mark != nullptr, "not an offset");
                                      return (csize_t)(_mark - _start); }
  csize_t     capacity() const      { return (csize_t)(_limit - _start); }
  csize_t     remaining() const     { return (csize_t)(_limit - _end); }

  relocInfo*  locs_start() const    { return _locs_start; }
  relocInfo*  locs_end() const      { return _locs_end; }
  int         locs_count() const    { return (int)(_locs_end - _locs_start); }
  relocInfo*  locs_limit() const    { return _locs_limit; }
  address     locs_point() const    { return _locs_point; }
  csize_t     locs_point_off() const{ return (csize_t)(_locs_point - _start); }
  csize_t     locs_capacity() const { return (csize_t)(_locs_limit - _locs_start); }

  int8_t      index() const         { return _index; }
  bool        is_allocated() const  { return _start != nullptr; }
  bool        is_empty() const      { return _start == _end; }
  bool        has_locs() const      { return _locs_end != nullptr; }

  // Mark scratch buffer.
  void        set_scratch_emit()    { _scratch_emit = true; }
  void        clear_scratch_emit()  { _scratch_emit = false; }
  bool        scratch_emit()        { return _scratch_emit; }

  CodeBuffer* outer() const         { return _outer; }

  // is a given address in this section?  (2nd version is end-inclusive)
  bool contains(address pc) const   { return pc >= _start && pc <  _end; }
  bool contains2(address pc) const  { return pc >= _start && pc <= _end; }
  bool allocates(address pc) const  { return pc >= _start && pc <  _limit; }
  bool allocates2(address pc) const { return pc >= _start && pc <= _limit; }

  // checks if two CodeSections are disjoint
  //
  // limit is an exclusive address and can be the start of another
  // section.
  bool disjoint(CodeSection* cs) const { return cs->_limit <= _start || cs->_start >= _limit; }

  void    set_end(address pc)       { assert(allocates2(pc), "not in CodeBuffer memory: " INTPTR_FORMAT " <= " INTPTR_FORMAT " <= " INTPTR_FORMAT, p2i(_start), p2i(pc), p2i(_limit)); _end = pc; }
  void    set_mark(address pc)      { assert(contains2(pc), "not in codeBuffer");
                                      _mark = pc; }
  void    set_mark()                { _mark = _end; }
  void    clear_mark()              { _mark = nullptr; }

  void    set_locs_end(relocInfo* p) {
    assert(p <= locs_limit(), "locs data fits in allocated buffer");
    _locs_end = p;
  }
  void    set_locs_point(address pc) {
    assert(pc >= locs_point(), "relocation addr may not decrease");
    assert(allocates2(pc),     "relocation addr " INTPTR_FORMAT " must be in this section from " INTPTR_FORMAT " to " INTPTR_FORMAT, p2i(pc), p2i(_start), p2i(_limit));
    _locs_point = pc;
  }

  void register_skipped(int size) {
    _skipped_instructions_size += size;
  }

  // Code emission
  void emit_int8(uint8_t x1) {
    address curr = end();
    *((uint8_t*)  curr++) = x1;
    set_end(curr);
  }

  template <typename T>
  void emit_native(T x) { put_native(end(), x); set_end(end() + sizeof x); }

  void emit_int16(uint16_t x) { emit_native(x); }
  void emit_int16(uint8_t x1, uint8_t x2) {
    address curr = end();
    *((uint8_t*)  curr++) = x1;
    *((uint8_t*)  curr++) = x2;
    set_end(curr);
  }

  void emit_int24(uint8_t x1, uint8_t x2, uint8_t x3)  {
    address curr = end();
    *((uint8_t*)  curr++) = x1;
    *((uint8_t*)  curr++) = x2;
    *((uint8_t*)  curr++) = x3;
    set_end(curr);
  }

  void emit_int32(uint32_t x) { emit_native(x); }
  void emit_int32(uint8_t x1, uint8_t x2, uint8_t x3, uint8_t x4)  {
    address curr = end();
    *((uint8_t*)  curr++) = x1;
    *((uint8_t*)  curr++) = x2;
    *((uint8_t*)  curr++) = x3;
    *((uint8_t*)  curr++) = x4;
    set_end(curr);
  }

  void emit_int64(uint64_t x)  { emit_native(x); }
  void emit_float(jfloat  x)   { emit_native(x); }
  void emit_double(jdouble x)  { emit_native(x); }
  void emit_address(address x) { emit_native(x); }

  // Share a scratch buffer for relocinfo.  (Hacky; saves a resource allocation.)
  void initialize_shared_locs(relocInfo* buf, int length);

  // Manage labels and their addresses.
  address target(Label& L, address branch_pc);

  // Emit a relocation.
  void relocate(address at, RelocationHolder const& rspec, int format = 0);
  void relocate(address at,    relocInfo::relocType rtype, int format = 0, jint method_index = 0);

  int alignment() const;

  // Slop between sections, used only when allocating temporary BufferBlob buffers.
  static csize_t end_slop()         { return MAX2((int)sizeof(jdouble), (int)CodeEntryAlignment); }

  csize_t align_at_start(csize_t off) const {
    return (csize_t) align_up(off, alignment());
  }

  // Ensure there's enough space left in the current section.
  // Return true if there was an expansion.
  bool maybe_expand_to_ensure_remaining(csize_t amount);

#ifndef PRODUCT
  void decode();
  void print_on(outputStream* st, const char* name);
#endif //PRODUCT
};


#ifndef PRODUCT

// ----- CHeapString -----------------------------------------------------------

class CHeapString : public CHeapObj<mtCode> {
 public:
  CHeapString(const char* str) : _string(os::strdup(str)) {}
  ~CHeapString();
  const char* string() const { return _string; }

 private:
  const char* _string;
};

// ----- AsmRemarkCollection ---------------------------------------------------

class AsmRemarkCollection : public CHeapObj<mtCode> {
 public:
  AsmRemarkCollection() : _ref_cnt(1), _remarks(nullptr), _next(nullptr) {}
 ~AsmRemarkCollection() {
    assert(is_empty(), "Must 'clear()' before deleting!");
    assert(_ref_cnt == 0, "No uses must remain when deleting!");
  }
  AsmRemarkCollection* reuse() {
    precond(_ref_cnt > 0);
    return _ref_cnt++, this;
  }

  const char* insert(uint offset, const char* remark);
  const char* lookup(uint offset) const;
  const char* next(uint offset) const;

  bool is_empty() const { return _remarks == nullptr; }
  uint clear();

  template<typename Function>
  bool iterate(Function function) const { // lambda enabled API
    if (_remarks != nullptr) {
      Cell* tmp = _remarks;
      do {
        if(!function(tmp->offset, tmp->string())) {
          return false;
        }
        tmp = tmp->next;
      } while (tmp != _remarks);
    }
    return true;
  }

 private:
  struct Cell : CHeapString {
    Cell(const char* remark, uint offset) :
        CHeapString(remark), offset(offset), prev(nullptr), next(nullptr) {}
    void push_back(Cell* cell) {
      Cell* head = this;
      Cell* tail = prev;
      tail->next = cell;
      cell->next = head;
      cell->prev = tail;
      prev = cell;
    }
    uint offset;
    Cell* prev;
    Cell* next;
  };
  uint  _ref_cnt;
  Cell* _remarks;
  // Using a 'mutable' iteration pointer to allow 'const' on lookup/next (that
  // does not change the state of the list per se), supportig a simplistic
  // iteration scheme.
  mutable Cell* _next;
};

// ----- DbgStringCollection ---------------------------------------------------

class DbgStringCollection : public CHeapObj<mtCode> {
 public:
  DbgStringCollection() : _ref_cnt(1), _strings(nullptr) {}
 ~DbgStringCollection() {
    assert(is_empty(), "Must 'clear()' before deleting!");
    assert(_ref_cnt == 0, "No uses must remain when deleting!");
  }
  DbgStringCollection* reuse() {
    precond(_ref_cnt > 0);
    return _ref_cnt++, this;
  }

  const char* insert(const char* str);
  const char* lookup(const char* str) const;

  bool is_empty() const { return _strings == nullptr; }
  uint clear();

  template<typename Function>
  bool iterate(Function function) const { // lambda enabled API
    if (_strings != nullptr) {
      Cell* tmp = _strings;
      do {
        if (!function(tmp->string())) {
          return false;
        }
        tmp = tmp->next;
      } while (tmp != _strings);
    }
    return true;
  }

 private:
  struct Cell : CHeapString {
    Cell(const char* dbgstr) :
        CHeapString(dbgstr), prev(nullptr), next(nullptr) {}
    void push_back(Cell* cell) {
      Cell* head = this;
      Cell* tail = prev;
      tail->next = cell;
      cell->next = head;
      cell->prev = tail;
      prev = cell;
    }
    Cell* prev;
    Cell* next;
  };
  uint  _ref_cnt;
  Cell* _strings;
};

// The assumption made here is that most code remarks (or comments) added to
// the generated assembly code are unique, i.e. there is very little gain in
// trying to share the strings between the different offsets tracked in a
// buffer (or blob).

class AsmRemarks {
 public:
  AsmRemarks();
 ~AsmRemarks();

  void init();

  const char* insert(uint offset, const char* remstr);

  bool is_empty() const;

  void share(const AsmRemarks &src);
  void clear();
  uint print(uint offset, outputStream* strm = tty) const;

  // For testing purposes only.
  const AsmRemarkCollection* ref() const { return _remarks; }

  template<typename Function>
  inline bool iterate(Function function) const { return _remarks->iterate(function); }

private:
  AsmRemarkCollection* _remarks;
};

// The assumption made here is that the number of debug strings (with a fixed
// address requirement) is a rather small set per compilation unit.

class DbgStrings {
 public:
  DbgStrings();
 ~DbgStrings();

  void init();

  const char* insert(const char* dbgstr);

  bool is_empty() const;

  void share(const DbgStrings &src);
  void clear();

  // For testing purposes only.
  const DbgStringCollection* ref() const { return _strings; }

  template<typename Function>
  bool iterate(Function function) const { return _strings->iterate(function); }

private:
  DbgStringCollection* _strings;
};
#endif // not PRODUCT


#ifdef ASSERT
#include "utilities/copy.hpp"

class Scrubber {
 public:
  Scrubber(void* addr, size_t size) : _addr(addr), _size(size) {}
 ~Scrubber() {
    Copy::fill_to_bytes(_addr, _size, badResourceValue);
  }
 private:
  void*  _addr;
  size_t _size;
};
#endif // ASSERT

typedef GrowableArray<SharedStubToInterpRequest> SharedStubToInterpRequests;

// A CodeBuffer describes a memory space into which assembly
// code is generated.  This memory space usually occupies the
// interior of a single BufferBlob, but in some cases it may be
// an arbitrary span of memory, even outside the code cache.
//
// A code buffer comes in two variants:
//
// (1) A CodeBuffer referring to an already allocated piece of memory:
//     This is used to direct 'static' code generation (e.g. for interpreter
//     or stubroutine generation, etc.).  This code comes with NO relocation
//     information.
//
// (2) A CodeBuffer referring to a piece of memory allocated when the
//     CodeBuffer is allocated.  This is used for nmethod generation.
//
// The memory can be divided up into several parts called sections.
// Each section independently accumulates code (or data) an relocations.
// Sections can grow (at the expense of a reallocation of the BufferBlob
// and recopying of all active sections).  When the buffered code is finally
// written to an nmethod (or other CodeBlob), the contents (code, data,
// and relocations) of the sections are padded to an alignment and concatenated.
// Instructions and data in one section can contain relocatable references to
// addresses in a sibling section.

class CodeBuffer: public StackObj DEBUG_ONLY(COMMA private Scrubber) {
  friend class CodeSection;
  friend class StubCodeGenerator;
  friend class AOTCodeReader;

 private:
  // CodeBuffers must be allocated on the stack except for a single
  // special case during expansion which is handled internally.  This
  // is done to guarantee proper cleanup of resources.
  void* operator new(size_t size) throw() { return resource_allocate_bytes(size); }
  void  operator delete(void* p)          { ShouldNotCallThis(); }

 public:
  typedef int csize_t;  // code size type; would be size_t except for history
  enum : int8_t {
    // Here is the list of all possible sections.  The order reflects
    // the final layout.
    SECT_FIRST = 0,
    SECT_CONSTS = SECT_FIRST, // Non-instruction data:  Floats, jump tables, etc.
    SECT_INSTS,               // Executable instructions.
    SECT_STUBS,               // Outbound trampolines for supporting call sites.
    SECT_LIMIT, SECT_NONE = -1
  };

  typedef LinkedListImpl<int> Offsets;
  typedef ResizeableResourceHashtable<address, Offsets, AnyObj::C_HEAP, mtCompiler> SharedTrampolineRequests;

 private:
  enum {
    sect_bits = 2,      // assert (SECT_LIMIT <= (1<<sect_bits))
    sect_mask = (1<<sect_bits)-1
  };

  const char*  _name;

  CodeSection  _consts;             // constants, jump tables
  CodeSection  _insts;              // instructions (the main section)
  CodeSection  _stubs;              // stubs (call site support), deopt, exception handling

  CodeBuffer*  _before_expand;  // dead buffer, from before the last expansion

  BufferBlob*  _blob;           // optional buffer in CodeCache for generated code
  address      _total_start;    // first address of combined memory buffer
  csize_t      _total_size;     // size in bytes of combined memory buffer

  OopRecorder* _oop_recorder;

  OopRecorder  _default_oop_recorder;  // override with initialize_oop_recorder
  Arena*       _overflow_arena;

  address      _last_insn;      // used to merge consecutive memory barriers, loads or stores.
  address      _last_label;     // record last bind label address, it's also the start of current bb.

  SharedStubToInterpRequests* _shared_stub_to_interp_requests; // used to collect requests for shared iterpreter stubs
  SharedTrampolineRequests*   _shared_trampoline_requests;     // used to collect requests for shared trampolines
  bool         _finalize_stubs; // Indicate if we need to finalize stubs to make CodeBuffer final.

  int          _const_section_alignment;

#ifndef PRODUCT
  AsmRemarks   _asm_remarks;
  DbgStrings   _dbg_strings;
  bool         _collect_comments; // Indicate if we need to collect block comments at all.
  address      _decode_begin;     // start address for decode
  address      decode_begin();
#endif

  void initialize_misc(const char * name) {
    // all pointers other than code_start/end and those inside the sections
    assert(name != nullptr, "must have a name");
    _name            = name;
    _before_expand   = nullptr;
    _blob            = nullptr;
    _total_start     = nullptr;
    _total_size      = 0;
    _oop_recorder    = nullptr;
    _overflow_arena  = nullptr;
    _last_insn       = nullptr;
    _last_label      = nullptr;
    _finalize_stubs  = false;
    _shared_stub_to_interp_requests = nullptr;
    _shared_trampoline_requests = nullptr;

    _consts.initialize_outer(this, SECT_CONSTS);
    _insts.initialize_outer(this,  SECT_INSTS);
    _stubs.initialize_outer(this,  SECT_STUBS);

    // Default is to align on 8 bytes. A compiler can change this
    // if larger alignment (e.g., 32-byte vector masks) is required.
    _const_section_alignment = (int) sizeof(jdouble);

#ifndef PRODUCT
    _decode_begin    = nullptr;
    // Collect block comments, but restrict collection to cases where a disassembly is output.
    _collect_comments = ( PrintAssembly
                       || PrintStubCode
                       || PrintMethodHandleStubs
                       || PrintInterpreter
                       || PrintSignatureHandlers
                       || UnlockDiagnosticVMOptions
                        );
#endif
  }

  void initialize(address code_start, csize_t code_size) {
    _total_start = code_start;
    _total_size  = code_size;
    // Initialize the main section:
    _insts.initialize(code_start, code_size);
    assert(!_stubs.is_allocated(),  "no garbage here");
    assert(!_consts.is_allocated(), "no garbage here");
    _oop_recorder = &_default_oop_recorder;
  }

  void initialize_section_size(CodeSection* cs, csize_t size);

  // helper for CodeBuffer::expand()
  void take_over_code_from(CodeBuffer* cs);

  // ensure sections are disjoint, ordered, and contained in the blob
  void verify_section_allocation();

  // copies combined relocations to the blob, returns bytes copied
  // (if target is null, it is a dry run only, just for sizing)
  csize_t copy_relocations_to(CodeBlob* blob) const;

  // copies combined code to the blob (assumes relocs are already in there)
  void copy_code_to(CodeBlob* blob);

  // moves code sections to new buffer (assumes relocs are already in there)
  void relocate_code_to(CodeBuffer* cb) const;

  // adjust some internal address during expand
  void adjust_internal_address(address from, address to);

  // set up a model of the final layout of my contents
  void compute_final_layout(CodeBuffer* dest) const;

  // Expand the given section so at least 'amount' is remaining.
  // Creates a new, larger BufferBlob, and rewrites the code & relocs.
  void expand(CodeSection* which_cs, csize_t amount);

  // Helper for expand.
  csize_t figure_expanded_capacities(CodeSection* which_cs, csize_t amount, csize_t* new_capacity);

 public:
  // (1) code buffer referring to pre-allocated instruction memory
  CodeBuffer(address code_start, csize_t code_size)
    DEBUG_ONLY(: Scrubber(this, sizeof(*this)))
  {
    assert(code_start != nullptr, "sanity");
    initialize_misc("static buffer");
    initialize(code_start, code_size);
    DEBUG_ONLY(verify_section_allocation();)
  }

  // (2) CodeBuffer referring to pre-allocated CodeBlob.
  CodeBuffer(CodeBlob* blob);

  // (3) code buffer allocating codeBlob memory for code & relocation
  // info but with lazy initialization.  The name must be something
  // informative.
  CodeBuffer(const char* name)
    DEBUG_ONLY(: Scrubber(this, sizeof(*this)))
  {
    initialize_misc(name);
  }

  // (4) code buffer allocating codeBlob memory for code & relocation
  // info.  The name must be something informative and code_size must
  // include both code and stubs sizes.
  CodeBuffer(const char* name, csize_t code_size, csize_t locs_size)
    DEBUG_ONLY(: Scrubber(this, sizeof(*this)))
  {
    initialize_misc(name);
    initialize(code_size, locs_size);
  }

  ~CodeBuffer();

  // Initialize a CodeBuffer constructed using constructor 3.  Using
  // constructor 4 is equivalent to calling constructor 3 and then
  // calling this method.  It's been factored out for convenience of
  // construction.
  void initialize(csize_t code_size, csize_t locs_size);

  CodeSection* consts() { return &_consts; }
  CodeSection* insts() { return &_insts; }
  CodeSection* stubs() { return &_stubs; }

  const CodeSection* insts() const { return &_insts; }

  // present sections in order; return null at end; consts is #0, etc.
  CodeSection* code_section(int n) {
    // This makes the slightly questionable but portable assumption
    // that the various members (_consts, _insts, _stubs, etc.) are
    // adjacent in the layout of CodeBuffer.
    CodeSection* cs = &_consts + n;
    assert(cs->index() == n || !cs->is_allocated(), "sanity");
    return cs;
  }
  const CodeSection* code_section(int n) const {  // yucky const stuff
    return ((CodeBuffer*)this)->code_section(n);
  }
  static const char* code_section_name(int n);
  int section_index_of(address addr) const;
  bool contains(address addr) const {
    // handy for debugging
    return section_index_of(addr) > SECT_NONE;
  }

  // A stable mapping between 'locators' (small ints) and addresses.
  static int locator_pos(int locator)   { return locator >> sect_bits; }
  static int locator_sect(int locator)  { return locator &  sect_mask; }
  static int locator(int pos, int sect) { return (pos << sect_bits) | sect; }
  int        locator(address addr) const;
  address    locator_address(int locator) const {
    if (locator < 0)  return nullptr;
    address start = code_section(locator_sect(locator))->start();
    return start + locator_pos(locator);
  }

  // Heuristic for pre-packing the taken/not-taken bit of a predicted branch.
  bool is_backward_branch(Label& L);

  // Properties
  const char* name() const                  { return _name; }
  CodeBuffer* before_expand() const         { return _before_expand; }
  BufferBlob* blob() const                  { return _blob; }
  void    set_blob(BufferBlob* blob);
  void   free_blob();                       // Free the blob, if we own one.

  // Properties relative to the insts section:
  address       insts_begin() const      { return _insts.start();      }
  address       insts_end() const        { return _insts.end();        }
  void      set_insts_end(address end)   {        _insts.set_end(end); }
  address       insts_mark() const       { return _insts.mark();       }
  void      set_insts_mark()             {        _insts.set_mark();   }

  // is there anything in the buffer other than the current section?
  bool    is_pure() const                { return insts_size() == total_content_size(); }

  // size in bytes of output so far in the insts sections
  csize_t insts_size() const             { return _insts.size(); }

  // same as insts_size(), except that it asserts there is no non-code here
  csize_t pure_insts_size() const        { assert(is_pure(), "no non-code");
                                           return insts_size(); }
  // capacity in bytes of the insts sections
  csize_t insts_capacity() const         { return _insts.capacity(); }

  // number of bytes remaining in the insts section
  csize_t insts_remaining() const        { return _insts.remaining(); }

  // is a given address in the insts section?  (2nd version is end-inclusive)
  bool insts_contains(address pc) const  { return _insts.contains(pc); }
  bool insts_contains2(address pc) const { return _insts.contains2(pc); }

  // Record any extra oops required to keep embedded metadata alive
  void finalize_oop_references(const methodHandle& method);

  // Allocated size in all sections, when aligned and concatenated
  // (this is the eventual state of the content in its final
  // CodeBlob).
  csize_t total_content_size() const;

  // Combined offset (relative to start of first section) of given
  // section, as eventually found in the final CodeBlob.
  csize_t total_offset_of(const CodeSection* cs) const;

  // allocated size of all relocation data, including index, rounded up
  csize_t total_relocation_size() const;

  int total_skipped_instructions_size() const;

  csize_t copy_relocations_to(address buf, csize_t buf_limit, bool only_inst) const;

  // allocated size of any and all recorded oops
  csize_t total_oop_size() const {
    OopRecorder* recorder = oop_recorder();
    return (recorder == nullptr)? 0: recorder->oop_size();
  }

  // allocated size of any and all recorded metadata
  csize_t total_metadata_size() const {
    OopRecorder* recorder = oop_recorder();
    return (recorder == nullptr)? 0: recorder->metadata_size();
  }

  // Configuration functions, called immediately after the CB is constructed.
  // The section sizes are subtracted from the original insts section.
  // Note:  Call them in reverse section order, because each steals from insts.
  void initialize_consts_size(csize_t size)            { initialize_section_size(&_consts,  size); }
  void initialize_stubs_size(csize_t size)             { initialize_section_size(&_stubs,   size); }
  // Override default oop recorder.
  void initialize_oop_recorder(OopRecorder* r);

  OopRecorder* oop_recorder() const { return _oop_recorder; }

  address last_insn() const { return _last_insn; }
  void set_last_insn(address a) { _last_insn = a; }
  void clear_last_insn() { set_last_insn(nullptr); }

  address last_label() const { return _last_label; }
  void set_last_label(address a) { _last_label = a; }

#ifndef PRODUCT
  AsmRemarks &asm_remarks() { return _asm_remarks; }
  DbgStrings &dbg_strings() { return _dbg_strings; }

  void clear_strings() {
    _asm_remarks.clear();
    _dbg_strings.clear();
  }
#endif

  // Code generation
  void relocate(address at, RelocationHolder const& rspec, int format = 0) {
    _insts.relocate(at, rspec, format);
  }
  void relocate(address at,    relocInfo::relocType rtype, int format = 0) {
    _insts.relocate(at, rtype, format);
  }

  // Management of overflow storage for binding of Labels.
  GrowableArray<int>* create_patch_overflow();

  // NMethod generation
  void copy_code_and_locs_to(CodeBlob* blob) {
    assert(blob != nullptr, "sane");
    copy_relocations_to(blob);
    copy_code_to(blob);
  }
  void copy_values_to(nmethod* nm) {
    if (!oop_recorder()->is_unused()) {
      oop_recorder()->copy_values_to(nm);
    }
  }

  void block_comment(ptrdiff_t offset, const char* comment) PRODUCT_RETURN;
  const char* code_string(const char* str) PRODUCT_RETURN_(return nullptr;);

  // Log a little info about section usage in the CodeBuffer
  void log_section_sizes(const char* name);

  // Make a set of stubs final. It can create/optimize stubs.
  bool finalize_stubs();

  // Request for a shared stub to the interpreter
  void shared_stub_to_interp_for(ciMethod* callee, csize_t call_offset);

  void set_const_section_alignment(int align) {
    _const_section_alignment = align_up(align, HeapWordSize);
  }

#ifndef PRODUCT
 public:
  // Printing / Decoding
  // decodes from decode_begin() to code_end() and sets decode_begin to end
  void    decode();
  void    print_on(outputStream* st);
#endif
  // Directly disassemble code buffer.
  void    decode(address start, address end);

  // The following header contains architecture-specific implementations
#include CPU_HEADER(codeBuffer)

};

// A Java method can have calls of Java methods which can be statically bound.
// Calls of Java methods need stubs to the interpreter. Calls sharing the same Java method
// can share a stub to the interpreter.
// A SharedStubToInterpRequest is a request for a shared stub to the interpreter.
class SharedStubToInterpRequest : public ResourceObj {
 private:
  ciMethod* _shared_method;
  CodeBuffer::csize_t _call_offset; // The offset of the call in CodeBuffer

 public:
  SharedStubToInterpRequest(ciMethod* method = nullptr, CodeBuffer::csize_t call_offset = -1) : _shared_method(method),
      _call_offset(call_offset) {}

  ciMethod* shared_method() const { return _shared_method; }
  CodeBuffer::csize_t call_offset() const { return _call_offset; }
};

inline bool CodeSection::maybe_expand_to_ensure_remaining(csize_t amount) {
  if (remaining() < amount) { _outer->expand(this, amount); return true; }
  return false;
}

#endif // SHARE_ASM_CODEBUFFER_HPP