/*

 * Copyright (c) 1997, 2019, 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

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 * questions.

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 */

#ifndef SHARE_ASM_CODEBUFFER_HPP

#define SHARE_ASM_CODEBUFFER_HPP

#include "code/oopRecorder.hpp"

#include "code/relocInfo.hpp"

#include "utilities/align.hpp"

#include "utilities/debug.hpp"

#include "utilities/macros.hpp"

class CodeStrings;

class PhaseCFG;

class Compile;

class BufferBlob;

class CodeBuffer;

class Label;

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;

 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        _frozen;          // no more expansion of this section

  bool        _scratch_emit;    // Buffer is used for scratch emit, don't relocate.

  char        _index;           // my section number (SECT_INST, etc.)

  CodeBuffer* _outer;           // enclosing CodeBuffer

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

  CodeSection() {

    _start         = NULL;

    _mark          = NULL;

    _end           = NULL;

    _limit         = NULL;

    _locs_start    = NULL;

    _locs_end      = NULL;

    _locs_limit    = NULL;

    _locs_point    = NULL;

    _locs_own      = false;

    _frozen        = false;

    _scratch_emit  = false;

    debug_only(_index = (char)-1);

    debug_only(_outer = (CodeBuffer*)badAddress);

  }

  void initialize_outer(CodeBuffer* outer, int index) {

    _outer = outer;

    _index = index;

  }

  void initialize(address start, csize_t size = 0) {

    assert(_start == NULL, "only one init step, please");

    _start         = start;

    _mark          = NULL;

    _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;

  }

 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 != NULL, "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); }

  csize_t     locs_remaining()const { return (csize_t)(_locs_limit - _locs_end); }

  int         index() const         { return _index; }

  bool        is_allocated() const  { return _start != NULL; }

  bool        is_empty() const      { return _start == _end; }

  bool        is_frozen() const     { return _frozen; }

  bool        has_locs() const      { return _locs_end != NULL; }

  // Mark scratch buffer.

  void        set_scratch_emit()    { _scratch_emit = true; }

  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; }

  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_off(int offset)  { assert(contains2(offset+_start),"not in codeBuffer");

                                      _mark = offset + _start; }

  void    set_mark()                { _mark = _end; }

  void    clear_mark()              { _mark = NULL; }

  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 must be in this section");

    _locs_point = pc;

  }

  // Code emission

  void emit_int8 ( int8_t  x)  { *((int8_t*)  end()) = x; set_end(end() + sizeof(int8_t)); }

  void emit_int16( int16_t x)  { *((int16_t*) end()) = x; set_end(end() + sizeof(int16_t)); }

  void emit_int32( int32_t x)  { *((int32_t*) end()) = x; set_end(end() + sizeof(int32_t)); }

  void emit_int64( int64_t x)  { *((int64_t*) end()) = x; set_end(end() + sizeof(int64_t)); }

  void emit_float( jfloat  x)  { *((jfloat*)  end()) = x; set_end(end() + sizeof(jfloat)); }

  void emit_double(jdouble x)  { *((jdouble*) end()) = x; set_end(end() + sizeof(jdouble)); }

  void emit_address(address x) { *((address*) end()) = x; set_end(end() + sizeof(address)); }

  // 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);

  // alignment requirement for starting offset

  // Requirements are that the instruction area and the

  // stubs area must start on CodeEntryAlignment, and

  // the ctable on sizeof(jdouble)

  int alignment() const             { return MAX2((int)sizeof(jdouble), (int)CodeEntryAlignment); }

  // 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()); }

  // Mark a section frozen.  Assign its remaining space to

  // the following section.  It will never expand after this point.

  inline void freeze();         //  { _outer->freeze_section(this); }

  // 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(const char* name);

#endif //PRODUCT

};

class CodeString;

class CodeStrings {

private:

#ifndef PRODUCT

  CodeString* _strings;

#ifdef ASSERT

  // Becomes true after copy-out, forbids further use.

  bool _defunct; // Zero bit pattern is "valid", see memset call in decode_env::decode_env

#endif

  static const char* _prefix; // defaults to " ;; "

#endif

  CodeString* find(intptr_t offset) const;

  CodeString* find_last(intptr_t offset) const;

  void set_null_and_invalidate() {

#ifndef PRODUCT

    _strings = NULL;

#ifdef ASSERT

    _defunct = true;

#endif

#endif

  }

public:

  CodeStrings() {

#ifndef PRODUCT

    _strings = NULL;

#ifdef ASSERT

    _defunct = false;

#endif

#endif

  }

  bool is_null() {

#ifdef ASSERT

    return _strings == NULL;

#else

    return true;

#endif

  }

  const char* add_string(const char * string) PRODUCT_RETURN_(return NULL;);

  void add_comment(intptr_t offset, const char * comment) PRODUCT_RETURN;

  void print_block_comment(outputStream* stream, intptr_t offset) const PRODUCT_RETURN;

  // MOVE strings from other to this; invalidate other.

  void assign(CodeStrings& other)  PRODUCT_RETURN;

  // COPY strings from other to this; leave other valid.

  void copy(CodeStrings& other)  PRODUCT_RETURN;

  // FREE strings; invalidate this.

  void free() PRODUCT_RETURN;

  // Guarantee that _strings are used at most once; assign and free invalidate a buffer.

  inline void check_valid() const {

#ifdef ASSERT

    assert(!_defunct, "Use of invalid CodeStrings");

#endif

  }

  static void set_prefix(const char *prefix) {

#ifndef PRODUCT

    _prefix = prefix;

#endif

  }

};

// 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 {

  friend class CodeSection;

  friend class StubCodeGenerator;

 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 ResourceObj::operator new(size); }

  void  operator delete(void* p)          { ShouldNotCallThis(); }

 public:

  typedef int csize_t;  // code size type; would be size_t except for history

  enum {

    // 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

  };

 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;

  CodeStrings  _code_strings;

  OopRecorder  _default_oop_recorder;  // override with initialize_oop_recorder

  Arena*       _overflow_arena;

  address      _last_insn;      // used to merge consecutive memory barriers, loads or stores.

#if INCLUDE_AOT

  bool         _immutable_PIC;

#endif

  address      _decode_begin;   // start address for decode

  address      decode_begin();

  void initialize_misc(const char * name) {

    // all pointers other than code_start/end and those inside the sections

    assert(name != NULL, "must have a name");

    _name            = name;

    _before_expand   = NULL;

    _blob            = NULL;

    _oop_recorder    = NULL;

    _decode_begin    = NULL;

    _overflow_arena  = NULL;

    _code_strings    = CodeStrings();

    _last_insn       = NULL;

#if INCLUDE_AOT

    _immutable_PIC   = false;

#endif

  }

  void initialize(address code_start, csize_t code_size) {

    _consts.initialize_outer(this,  SECT_CONSTS);

    _insts.initialize_outer(this,   SECT_INSTS);

    _stubs.initialize_outer(this,   SECT_STUBS);

    _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);

  void freeze_section(CodeSection* cs);

  // 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;

  // 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) {

    assert(code_start != NULL, "sanity");

    initialize_misc("static buffer");

    initialize(code_start, code_size);

    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) {

    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) {

    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; }