Google Git
Sign in
android / platform / external / jetbrains / jdk8u_hotspot / a482fc01a461b60a024295f544eaa063285fee2d / . / src / share / vm / code / relocInfo.hpp
blob: 68baf9edce54549500da1877d52a01fbeec396f0 [file] [log] [blame]
/*
* Copyright (c) 1997, 2013, 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_VM_CODE_RELOCINFO_HPP
#define SHARE_VM_CODE_RELOCINFO_HPP
#include "memory/allocation.hpp"
#include "utilities/top.hpp"
class NativeMovConstReg;
// 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.
// metadata_Relocation, ... (subclasses of Relocation)
// The location of some type-specific operations (metadata_addr, ...).
// Also, the source of relocation specs (metadata_Relocation::spec, ...).
// oop_Relocation, ... (subclasses of Relocation)
// oops in the code stream (strings, class loaders)
// 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.
// 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, relocInfo::metadata_type -- a reference to an oop or meta data
// 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::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
metadata_type = 12, // metadata that used to be oops
trampoline_stub_type = 13, // stub-entry for trampoline
yet_unused_type_1 = 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(metadata) \
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(section_word) \
visitor(trampoline_stub) \
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);
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
#ifdef TARGET_ARCH_x86
# include "relocInfo_x86.hpp"
#endif
#ifdef TARGET_ARCH_sparc
# include "relocInfo_sparc.hpp"
#endif
#ifdef TARGET_ARCH_zero
# include "relocInfo_zero.hpp"
#endif
#ifdef TARGET_ARCH_arm
# include "relocInfo_arm.hpp"
#endif
#ifdef TARGET_ARCH_ppc
# include "relocInfo_ppc.hpp"
#endif
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.
// 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 = 0) {
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);
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) throw() {
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");
}
static bool is_reloc_index(intptr_t index) {
return 0 < index && index < os::vm_page_size();
}
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, bool verify_only = false); // a set or mem-ref
void pd_verify_data_value (address x, intptr_t off) { pd_set_data_value(x, off, true); }
address pd_call_destination (address orig_addr = NULL);
void pd_set_call_destination (address x);
// 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);
}
void verify_value(address x) {
if (addr_in_const())
assert(*(address*)addr() == x, "must agree");
else
pd_verify_data_value(x, offset());
}
// 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
void verify_oop_relocation();
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.
};
// copy of oop_Relocation for now but may delete stuff in both/either
class metadata_Relocation : public DataRelocation {
relocInfo::relocType type() { return relocInfo::metadata_type; }
public:
// encode in one of these formats: [] [n] [n l] [Nn l] [Nn Ll]
// an metadata in the CodeBlob's metadata pool
static RelocationHolder spec(int metadata_index, int offset = 0) {
assert(metadata_index > 0, "must be a pool-resident metadata");
RelocationHolder rh = newHolder();
new(rh) metadata_Relocation(metadata_index, offset);
return rh;
}
// an metadata in the instruction stream
static RelocationHolder spec_for_immediate() {
const int metadata_index = 0;
const int offset = 0; // if you want an offset, use the metadata pool
RelocationHolder rh = newHolder();
new(rh) metadata_Relocation(metadata_index, offset);
return rh;
}
private:
jint _metadata_index; // if > 0, index into nmethod::metadata_at
jint _offset; // byte offset to apply to the metadata itself
metadata_Relocation(int metadata_index, int offset) {
_metadata_index = metadata_index; _offset = offset;
}
friend class RelocIterator;
metadata_Relocation() { }
// Fixes a Metadata pointer in the code. Most platforms embeds the
// Metadata pointer in the code at compile time so this is empty
// for them.
void pd_fix_value(address x);
public:
int metadata_index() { return _metadata_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_metadata_relocation(); // reasserts metadata value
void verify_metadata_relocation();
address value() { return (address) *metadata_addr(); }
bool metadata_is_immediate() { return metadata_index() == 0; }
Metadata** metadata_addr(); // addr or &pool[jint_data]
Metadata* metadata_value(); // *metadata_addr
// Note: metadata_value transparently converts Universe::non_metadata_word to NULL.
};
class virtual_call_Relocation : public CallRelocation {
relocInfo::relocType type() { return relocInfo::virtual_call_type; }
public:
// "cached_value" 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 cached_value) {
RelocationHolder rh = newHolder();
new(rh) virtual_call_Relocation(cached_value);
return rh;
}
virtual_call_Relocation(address cached_value) {
_cached_value = cached_value;
assert(cached_value != NULL, "first oop address must be specified");
}
private:
address _cached_value; // location of set-value instruction
friend class RelocIterator;
virtual_call_Relocation() { }
public:
address cached_value();
// 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();
};
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:
};
// Trampoline Relocations.
// A trampoline allows to encode a small branch in the code, even if there
// is the chance that this branch can not reach all possible code locations.
// If the relocation finds that a branch is too far for the instruction
// in the code, it can patch it to jump to the trampoline where is
// sufficient space for a far branch. Needed on PPC.
class trampoline_stub_Relocation : public Relocation {
relocInfo::relocType type() { return relocInfo::trampoline_stub_type; }
public:
static RelocationHolder spec(address static_call) {
RelocationHolder rh = newHolder();
return (new (rh) trampoline_stub_Relocation(static_call));
}
private:
address _owner; // Address of the NativeCall that owns the trampoline.
trampoline_stub_Relocation(address owner) {
_owner = owner;
}
friend class RelocIterator;
trampoline_stub_Relocation() { }
public:
// Return the address of the NativeCall that owns the trampoline.
address owner() { return _owner; }
void pack_data_to(CodeSection * dest);
void unpack_data();
// Find the trampoline stub for a call.
static address get_trampoline_for(address call, nmethod* code);
};
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;
}
// Some address looking values aren't safe to treat as relocations
// and should just be treated as constants.
static bool can_be_relocated(address target) {
return target != NULL && !is_reloc_index((intptr_t)target);
}
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);
};
// 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);
}
#endif // SHARE_VM_CODE_RELOCINFO_HPP