--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/code/relocInfo.hpp Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,1328 @@
+/*
+ * Copyright 1997-2006 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+// Types in this file:
+// relocInfo
+// One element of an array of halfwords encoding compressed relocations.
+// Also, the source of relocation types (relocInfo::oop_type, ...).
+// Relocation
+// A flyweight object representing a single relocation.
+// It is fully unpacked from the compressed relocation array.
+// oop_Relocation, ... (subclasses of Relocation)
+// The location of some type-specific operations (oop_addr, ...).
+// Also, the source of relocation specs (oop_Relocation::spec, ...).
+// RelocationHolder
+// A ValueObj type which acts as a union holding a Relocation object.
+// Represents a relocation spec passed into a CodeBuffer during assembly.
+// RelocIterator
+// A StackObj which iterates over the relocations associated with
+// a range of code addresses. Can be used to operate a copy of code.
+// PatchingRelocIterator
+// Specialized subtype of RelocIterator which removes breakpoints
+// temporarily during iteration, then restores them.
+// BoundRelocation
+// An _internal_ type shared by packers and unpackers of relocations.
+// It pastes together a RelocationHolder with some pointers into
+// code and relocInfo streams.
+
+
+// Notes on relocType:
+//
+// These hold enough information to read or write a value embedded in
+// the instructions of an CodeBlob. They're used to update:
+//
+// 1) embedded oops (isOop() == true)
+// 2) inline caches (isIC() == true)
+// 3) runtime calls (isRuntimeCall() == true)
+// 4) internal word ref (isInternalWord() == true)
+// 5) external word ref (isExternalWord() == true)
+//
+// when objects move (GC) or if code moves (compacting the code heap).
+// They are also used to patch the code (if a call site must change)
+//
+// A relocInfo is represented in 16 bits:
+// 4 bits indicating the relocation type
+// 12 bits indicating the offset from the previous relocInfo address
+//
+// The offsets accumulate along the relocInfo stream to encode the
+// address within the CodeBlob, which is named RelocIterator::addr().
+// The address of a particular relocInfo always points to the first
+// byte of the relevant instruction (and not to any of its subfields
+// or embedded immediate constants).
+//
+// The offset value is scaled appropriately for the target machine.
+// (See relocInfo_<arch>.hpp for the offset scaling.)
+//
+// On some machines, there may also be a "format" field which may provide
+// additional information about the format of the instruction stream
+// at the corresponding code address. The format value is usually zero.
+// Any machine (such as Intel) whose instructions can sometimes contain
+// more than one relocatable constant needs format codes to distinguish
+// which operand goes with a given relocation.
+//
+// If the target machine needs N format bits, the offset has 12-N bits,
+// the format is encoded between the offset and the type, and the
+// relocInfo_<arch>.hpp file has manifest constants for the format codes.
+//
+// If the type is "data_prefix_tag" then the offset bits are further encoded,
+// and in fact represent not a code-stream offset but some inline data.
+// The data takes the form of a counted sequence of halfwords, which
+// precedes the actual relocation record. (Clients never see it directly.)
+// The interpetation of this extra data depends on the relocation type.
+//
+// On machines that have 32-bit immediate fields, there is usually
+// little need for relocation "prefix" data, because the instruction stream
+// is a perfectly reasonable place to store the value. On machines in
+// which 32-bit values must be "split" across instructions, the relocation
+// data is the "true" specification of the value, which is then applied
+// to some field of the instruction (22 or 13 bits, on SPARC).
+//
+// Whenever the location of the CodeBlob changes, any PC-relative
+// relocations, and any internal_word_type relocations, must be reapplied.
+// After the GC runs, oop_type relocations must be reapplied.
+//
+//
+// Here are meanings of the types:
+//
+// relocInfo::none -- a filler record
+// Value: none
+// Instruction: The corresponding code address is ignored
+// Data: Any data prefix and format code are ignored
+// (This means that any relocInfo can be disabled by setting
+// its type to none. See relocInfo::remove.)
+//
+// relocInfo::oop_type -- a reference to an oop
+// Value: an oop, or else the address (handle) of an oop
+// Instruction types: memory (load), set (load address)
+// Data: [] an oop stored in 4 bytes of instruction
+// [n] n is the index of an oop in the CodeBlob's oop pool
+// [[N]n l] and l is a byte offset to be applied to the oop
+// [Nn Ll] both index and offset may be 32 bits if necessary
+// Here is a special hack, used only by the old compiler:
+// [[N]n 00] the value is the __address__ of the nth oop in the pool
+// (Note that the offset allows optimal references to class variables.)
+//
+// relocInfo::internal_word_type -- an address within the same CodeBlob
+// relocInfo::section_word_type -- same, but can refer to another section
+// Value: an address in the CodeBlob's code or constants section
+// Instruction types: memory (load), set (load address)
+// Data: [] stored in 4 bytes of instruction
+// [[L]l] a relative offset (see [About Offsets] below)
+// In the case of section_word_type, the offset is relative to a section
+// base address, and the section number (e.g., SECT_INSTS) is encoded
+// into the low two bits of the offset L.
+//
+// relocInfo::external_word_type -- a fixed address in the runtime system
+// Value: an address
+// Instruction types: memory (load), set (load address)
+// Data: [] stored in 4 bytes of instruction
+// [n] the index of a "well-known" stub (usual case on RISC)
+// [Ll] a 32-bit address
+//
+// relocInfo::runtime_call_type -- a fixed subroutine in the runtime system
+// Value: an address
+// Instruction types: PC-relative call (or a PC-relative branch)
+// Data: [] stored in 4 bytes of instruction
+//
+// relocInfo::static_call_type -- a static call
+// Value: an CodeBlob, a stub, or a fixup routine
+// Instruction types: a call
+// Data: []
+// The identity of the callee is extracted from debugging information.
+// //%note reloc_3
+//
+// relocInfo::virtual_call_type -- a virtual call site (which includes an inline
+// cache)
+// Value: an CodeBlob, a stub, the interpreter, or a fixup routine
+// Instruction types: a call, plus some associated set-oop instructions
+// Data: [] the associated set-oops are adjacent to the call
+// [n] n is a relative offset to the first set-oop
+// [[N]n l] and l is a limit within which the set-oops occur
+// [Nn Ll] both n and l may be 32 bits if necessary
+// The identity of the callee is extracted from debugging information.
+//
+// relocInfo::opt_virtual_call_type -- a virtual call site that is statically bound
+//
+// Same info as a static_call_type. We use a special type, so the handling of
+// virtuals and statics are separated.
+//
+//
+// The offset n points to the first set-oop. (See [About Offsets] below.)
+// In turn, the set-oop instruction specifies or contains an oop cell devoted
+// exclusively to the IC call, which can be patched along with the call.
+//
+// The locations of any other set-oops are found by searching the relocation
+// information starting at the first set-oop, and continuing until all
+// relocations up through l have been inspected. The value l is another
+// relative offset. (Both n and l are relative to the call's first byte.)
+//
+// The limit l of the search is exclusive. However, if it points within
+// the call (e.g., offset zero), it is adjusted to point after the call and
+// any associated machine-specific delay slot.
+//
+// Since the offsets could be as wide as 32-bits, these conventions
+// put no restrictions whatever upon code reorganization.
+//
+// The compiler is responsible for ensuring that transition from a clean
+// state to a monomorphic compiled state is MP-safe. This implies that
+// the system must respond well to intermediate states where a random
+// subset of the set-oops has been correctly from the clean state
+// upon entry to the VEP of the compiled method. In the case of a
+// machine (Intel) with a single set-oop instruction, the 32-bit
+// immediate field must not straddle a unit of memory coherence.
+// //%note reloc_3
+//
+// relocInfo::breakpoint_type -- a conditional breakpoint in the code
+// Value: none
+// Instruction types: any whatsoever
+// Data: [b [T]t i...]
+// The b is a bit-packed word representing the breakpoint's attributes.
+// The t is a target address which the breakpoint calls (when it is enabled).
+// The i... is a place to store one or two instruction words overwritten
+// by a trap, so that the breakpoint may be subsequently removed.
+//
+// relocInfo::static_stub_type -- an extra stub for each static_call_type
+// Value: none
+// Instruction types: a virtual call: { set_oop; jump; }
+// Data: [[N]n] the offset of the associated static_call reloc
+// This stub becomes the target of a static call which must be upgraded
+// to a virtual call (because the callee is interpreted).
+// See [About Offsets] below.
+// //%note reloc_2
+//
+// For example:
+//
+// INSTRUCTIONS RELOC: TYPE PREFIX DATA
+// ------------ ---- -----------
+// sethi %hi(myObject), R oop_type [n(myObject)]
+// ld [R+%lo(myObject)+fldOffset], R2 oop_type [n(myObject) fldOffset]
+// add R2, 1, R2
+// st R2, [R+%lo(myObject)+fldOffset] oop_type [n(myObject) fldOffset]
+//%note reloc_1
+//
+// This uses 4 instruction words, 8 relocation halfwords,
+// and an entry (which is sharable) in the CodeBlob's oop pool,
+// for a total of 36 bytes.
+//
+// Note that the compiler is responsible for ensuring the "fldOffset" when
+// added to "%lo(myObject)" does not overflow the immediate fields of the
+// memory instructions.
+//
+//
+// [About Offsets] Relative offsets are supplied to this module as
+// positive byte offsets, but they may be internally stored scaled
+// and/or negated, depending on what is most compact for the target
+// system. Since the object pointed to by the offset typically
+// precedes the relocation address, it is profitable to store
+// these negative offsets as positive numbers, but this decision
+// is internal to the relocation information abstractions.
+//
+
+class Relocation;
+class CodeBuffer;
+class CodeSection;
+class RelocIterator;
+
+class relocInfo VALUE_OBJ_CLASS_SPEC {
+ friend class RelocIterator;
+ public:
+ enum relocType {
+ none = 0, // Used when no relocation should be generated
+ oop_type = 1, // embedded oop
+ virtual_call_type = 2, // a standard inline cache call for a virtual send
+ opt_virtual_call_type = 3, // a virtual call that has been statically bound (i.e., no IC cache)
+ static_call_type = 4, // a static send
+ static_stub_type = 5, // stub-entry for static send (takes care of interpreter case)
+ runtime_call_type = 6, // call to fixed external routine
+ external_word_type = 7, // reference to fixed external address
+ internal_word_type = 8, // reference within the current code blob
+ section_word_type = 9, // internal, but a cross-section reference
+ poll_type = 10, // polling instruction for safepoints
+ poll_return_type = 11, // polling instruction for safepoints at return
+ breakpoint_type = 12, // an initialization barrier or safepoint
+ yet_unused_type = 13, // Still unused
+ yet_unused_type_2 = 14, // Still unused
+ data_prefix_tag = 15, // tag for a prefix (carries data arguments)
+ type_mask = 15 // A mask which selects only the above values
+ };
+
+ protected:
+ unsigned short _value;
+
+ enum RawBitsToken { RAW_BITS };
+ relocInfo(relocType type, RawBitsToken ignore, int bits)
+ : _value((type << nontype_width) + bits) { }
+
+ relocInfo(relocType type, RawBitsToken ignore, int off, int f)
+ : _value((type << nontype_width) + (off / (unsigned)offset_unit) + (f << offset_width)) { }
+
+ public:
+ // constructor
+ relocInfo(relocType type, int offset, int format = 0)
+#ifndef ASSERT
+ {
+ (*this) = relocInfo(type, RAW_BITS, offset, format);
+ }
+#else
+ // Put a bunch of assertions out-of-line.
+ ;
+#endif
+
+ #define APPLY_TO_RELOCATIONS(visitor) \
+ visitor(oop) \
+ visitor(virtual_call) \
+ visitor(opt_virtual_call) \
+ visitor(static_call) \
+ visitor(static_stub) \
+ visitor(runtime_call) \
+ visitor(external_word) \
+ visitor(internal_word) \
+ visitor(poll) \
+ visitor(poll_return) \
+ visitor(breakpoint) \
+ visitor(section_word) \
+
+
+ public:
+ enum {
+ value_width = sizeof(unsigned short) * BitsPerByte,
+ type_width = 4, // == log2(type_mask+1)
+ nontype_width = value_width - type_width,
+ datalen_width = nontype_width-1,
+ datalen_tag = 1 << datalen_width, // or-ed into _value
+ datalen_limit = 1 << datalen_width,
+ datalen_mask = (1 << datalen_width)-1
+ };
+
+ // accessors
+ public:
+ relocType type() const { return (relocType)((unsigned)_value >> nontype_width); }
+ int format() const { return format_mask==0? 0: format_mask &
+ ((unsigned)_value >> offset_width); }
+ int addr_offset() const { assert(!is_prefix(), "must have offset");
+ return (_value & offset_mask)*offset_unit; }
+
+ protected:
+ const short* data() const { assert(is_datalen(), "must have data");
+ return (const short*)(this + 1); }
+ int datalen() const { assert(is_datalen(), "must have data");
+ return (_value & datalen_mask); }
+ int immediate() const { assert(is_immediate(), "must have immed");
+ return (_value & datalen_mask); }
+ public:
+ static int addr_unit() { return offset_unit; }
+ static int offset_limit() { return (1 << offset_width) * offset_unit; }
+
+ void set_type(relocType type);
+ void set_format(int format);
+
+ void remove() { set_type(none); }
+
+ protected:
+ bool is_none() const { return type() == none; }
+ bool is_prefix() const { return type() == data_prefix_tag; }
+ bool is_datalen() const { assert(is_prefix(), "must be prefix");
+ return (_value & datalen_tag) != 0; }
+ bool is_immediate() const { assert(is_prefix(), "must be prefix");
+ return (_value & datalen_tag) == 0; }
+
+ public:
+ // Occasionally records of type relocInfo::none will appear in the stream.
+ // We do not bother to filter these out, but clients should ignore them.
+ // These records serve as "filler" in three ways:
+ // - to skip large spans of unrelocated code (this is rare)
+ // - to pad out the relocInfo array to the required oop alignment
+ // - to disable old relocation information which is no longer applicable
+
+ inline friend relocInfo filler_relocInfo();
+
+ // Every non-prefix relocation may be preceded by at most one prefix,
+ // which supplies 1 or more halfwords of associated data. Conventionally,
+ // an int is represented by 0, 1, or 2 halfwords, depending on how
+ // many bits are required to represent the value. (In addition,
+ // if the sole halfword is a 10-bit unsigned number, it is made
+ // "immediate" in the prefix header word itself. This optimization
+ // is invisible outside this module.)
+
+ inline friend relocInfo prefix_relocInfo(int datalen = 0);
+
+ protected:
+ // an immediate relocInfo optimizes a prefix with one 10-bit unsigned value
+ static relocInfo immediate_relocInfo(int data0) {
+ assert(fits_into_immediate(data0), "data0 in limits");
+ return relocInfo(relocInfo::data_prefix_tag, RAW_BITS, data0);
+ }
+ static bool fits_into_immediate(int data0) {
+ return (data0 >= 0 && data0 < datalen_limit);
+ }
+
+ public:
+ // Support routines for compilers.
+
+ // This routine takes an infant relocInfo (unprefixed) and
+ // edits in its prefix, if any. It also updates dest.locs_end.
+ void initialize(CodeSection* dest, Relocation* reloc);
+
+ // This routine updates a prefix and returns the limit pointer.
+ // It tries to compress the prefix from 32 to 16 bits, and if
+ // successful returns a reduced "prefix_limit" pointer.
+ relocInfo* finish_prefix(short* prefix_limit);
+
+ // bit-packers for the data array:
+
+ // As it happens, the bytes within the shorts are ordered natively,
+ // but the shorts within the word are ordered big-endian.
+ // This is an arbitrary choice, made this way mainly to ease debugging.
+ static int data0_from_int(jint x) { return x >> value_width; }
+ static int data1_from_int(jint x) { return (short)x; }
+ static jint jint_from_data(short* data) {
+ return (data[0] << value_width) + (unsigned short)data[1];
+ }
+
+ static jint short_data_at(int n, short* data, int datalen) {
+ return datalen > n ? data[n] : 0;
+ }
+
+ static jint jint_data_at(int n, short* data, int datalen) {
+ return datalen > n+1 ? jint_from_data(&data[n]) : short_data_at(n, data, datalen);
+ }
+
+ // Update methods for relocation information
+ // (since code is dynamically patched, we also need to dynamically update the relocation info)
+ // Both methods takes old_type, so it is able to performe sanity checks on the information removed.
+ static void change_reloc_info_for_address(RelocIterator *itr, address pc, relocType old_type, relocType new_type);
+ static void remove_reloc_info_for_address(RelocIterator *itr, address pc, relocType old_type);
+
+ // Machine dependent stuff
+ #include "incls/_relocInfo_pd.hpp.incl"
+
+ protected:
+ // Derived constant, based on format_width which is PD:
+ enum {
+ offset_width = nontype_width - format_width,
+ offset_mask = (1<<offset_width) - 1,
+ format_mask = (1<<format_width) - 1
+ };
+ public:
+ enum {
+ // Conservatively large estimate of maximum length (in shorts)
+ // of any relocation record (probably breakpoints are largest).
+ // Extended format is length prefix, data words, and tag/offset suffix.
+ length_limit = 1 + 1 + (3*BytesPerWord/BytesPerShort) + 1,
+ have_format = format_width > 0
+ };
+};
+
+#define FORWARD_DECLARE_EACH_CLASS(name) \
+class name##_Relocation;
+APPLY_TO_RELOCATIONS(FORWARD_DECLARE_EACH_CLASS)
+#undef FORWARD_DECLARE_EACH_CLASS
+
+
+
+inline relocInfo filler_relocInfo() {
+ return relocInfo(relocInfo::none, relocInfo::offset_limit() - relocInfo::offset_unit);
+}
+
+inline relocInfo prefix_relocInfo(int datalen) {
+ assert(relocInfo::fits_into_immediate(datalen), "datalen in limits");
+ return relocInfo(relocInfo::data_prefix_tag, relocInfo::RAW_BITS, relocInfo::datalen_tag | datalen);
+}
+
+
+// Holder for flyweight relocation objects.
+// Although the flyweight subclasses are of varying sizes,
+// the holder is "one size fits all".
+class RelocationHolder VALUE_OBJ_CLASS_SPEC {
+ friend class Relocation;
+ friend class CodeSection;
+
+ private:
+ // this preallocated memory must accommodate all subclasses of Relocation
+ // (this number is assertion-checked in Relocation::operator new)
+ enum { _relocbuf_size = 5 };
+ void* _relocbuf[ _relocbuf_size ];
+
+ public:
+ Relocation* reloc() const { return (Relocation*) &_relocbuf[0]; }
+ inline relocInfo::relocType type() const;
+
+ // Add a constant offset to a relocation. Helper for class Address.
+ RelocationHolder plus(int offset) const;
+
+ inline RelocationHolder(); // initializes type to none
+
+ inline RelocationHolder(Relocation* r); // make a copy
+
+ static const RelocationHolder none;
+};
+
+// A RelocIterator iterates through the relocation information of a CodeBlob.
+// It is a variable BoundRelocation which is able to take on successive
+// values as it is advanced through a code stream.
+// Usage:
+// RelocIterator iter(nm);
+// while (iter.next()) {
+// iter.reloc()->some_operation();
+// }
+// or:
+// RelocIterator iter(nm);
+// while (iter.next()) {
+// switch (iter.type()) {
+// case relocInfo::oop_type :
+// case relocInfo::ic_type :
+// case relocInfo::prim_type :
+// case relocInfo::uncommon_type :
+// case relocInfo::runtime_call_type :
+// case relocInfo::internal_word_type:
+// case relocInfo::external_word_type:
+// ...
+// }
+// }
+
+class RelocIterator : public StackObj {
+ enum { SECT_CONSTS = 2,
+ SECT_LIMIT = 3 }; // must be equal to CodeBuffer::SECT_LIMIT
+ 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
+ CodeBlob* _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];
+
+ 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() {
+ set_has_current(false);
+ for (int i = 0; i < SECT_LIMIT; i++) {
+ _section_start[i] = NULL; // these will be lazily computed, if needed
+ }
+ }
+
+ address compute_section_start(int n) const; // out-of-line helper
+
+ void initialize(CodeBlob* nm, address begin, address limit);
+
+ friend class PatchingRelocIterator;
+ // make an uninitialized one, for PatchingRelocIterator:
+ RelocIterator() { initialize_misc(); }
+
+ public:
+ // constructor
+ RelocIterator(CodeBlob* cb, 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; }
+ CodeBlob* 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 { return addr() >= section_start(SECT_CONSTS); }
+
+ address section_start(int n) const {
+ address res = _section_start[n];
+ return (res != NULL) ? res : compute_section_start(n);
+ }
+
+ // The address points to the affected displacement part of the instruction.
+ // For RISC, this is just the whole instruction.
+ // For Intel, this is an unaligned 32-bit word.
+
+ // type-specific relocation accessors: oop_Relocation* oop_reloc(), etc.
+ #define EACH_TYPE(name) \
+ inline name##_Relocation* name##_reloc();
+ APPLY_TO_RELOCATIONS(EACH_TYPE)
+ #undef EACH_TYPE
+ // generic relocation accessor; switches on type to call the above
+ Relocation* reloc();
+
+ // CodeBlob's have relocation indexes for faster random access:
+ static int locs_and_index_size(int code_size, int locs_size);
+ // Store an index into [dest_start+dest_count..dest_end).
+ // At dest_start[0..dest_count] is the actual relocation information.
+ // Everything else up to dest_end is free space for the index.
+ static void create_index(relocInfo* dest_begin, int dest_count, relocInfo* dest_end);
+
+#ifndef PRODUCT
+ public:
+ void print();
+ void print_current();
+#endif
+};
+
+
+// A Relocation is a flyweight object allocated within a RelocationHolder.
+// It represents the relocation data of relocation record.
+// So, the RelocIterator unpacks relocInfos into Relocations.
+
+class Relocation VALUE_OBJ_CLASS_SPEC {
+ friend class RelocationHolder;
+ friend class RelocIterator;
+
+ private:
+ static void guarantee_size();
+
+ // When a relocation has been created by a RelocIterator,
+ // this field is non-null. It allows the relocation to know
+ // its context, such as the address to which it applies.
+ RelocIterator* _binding;
+
+ protected:
+ RelocIterator* binding() const {
+ assert(_binding != NULL, "must be bound");
+ return _binding;
+ }
+ void set_binding(RelocIterator* b) {
+ assert(_binding == NULL, "must be unbound");
+ _binding = b;
+ assert(_binding != NULL, "must now be bound");
+ }
+
+ Relocation() {
+ _binding = NULL;
+ }
+
+ static RelocationHolder newHolder() {
+ return RelocationHolder();
+ }
+
+ public:
+ void* operator new(size_t size, const RelocationHolder& holder) {
+ if (size > sizeof(holder._relocbuf)) guarantee_size();
+ assert((void* const *)holder.reloc() == &holder._relocbuf[0], "ptrs must agree");
+ return holder.reloc();
+ }
+
+ // make a generic relocation for a given type (if possible)
+ static RelocationHolder spec_simple(relocInfo::relocType rtype);
+
+ // here is the type-specific hook which writes relocation data:
+ virtual void pack_data_to(CodeSection* dest) { }
+
+ // here is the type-specific hook which reads (unpacks) relocation data:
+ virtual void unpack_data() {
+ assert(datalen()==0 || type()==relocInfo::none, "no data here");
+ }
+
+ protected:
+ // Helper functions for pack_data_to() and unpack_data().
+
+ // Most of the compression logic is confined here.
+ // (The "immediate data" mechanism of relocInfo works independently
+ // of this stuff, and acts to further compress most 1-word data prefixes.)
+
+ // A variable-width int is encoded as a short if it will fit in 16 bits.
+ // The decoder looks at datalen to decide whether to unpack short or jint.
+ // Most relocation records are quite simple, containing at most two ints.
+
+ static bool is_short(jint x) { return x == (short)x; }
+ static short* add_short(short* p, int x) { *p++ = x; return p; }
+ static short* add_jint (short* p, jint x) {
+ *p++ = relocInfo::data0_from_int(x); *p++ = relocInfo::data1_from_int(x);
+ return p;
+ }
+ static short* add_var_int(short* p, jint x) { // add a variable-width int
+ if (is_short(x)) p = add_short(p, x);
+ else p = add_jint (p, x);
+ return p;
+ }
+
+ static short* pack_1_int_to(short* p, jint x0) {
+ // Format is one of: [] [x] [Xx]
+ if (x0 != 0) p = add_var_int(p, x0);
+ return p;
+ }
+ int unpack_1_int() {
+ assert(datalen() <= 2, "too much data");
+ return relocInfo::jint_data_at(0, data(), datalen());
+ }
+
+ // With two ints, the short form is used only if both ints are short.
+ short* pack_2_ints_to(short* p, jint x0, jint x1) {
+ // Format is one of: [] [x y?] [Xx Y?y]
+ if (x0 == 0 && x1 == 0) {
+ // no halfwords needed to store zeroes
+ } else if (is_short(x0) && is_short(x1)) {
+ // 1-2 halfwords needed to store shorts
+ p = add_short(p, x0); if (x1!=0) p = add_short(p, x1);
+ } else {
+ // 3-4 halfwords needed to store jints
+ p = add_jint(p, x0); p = add_var_int(p, x1);
+ }
+ return p;
+ }
+ void unpack_2_ints(jint& x0, jint& x1) {
+ int dlen = datalen();
+ short* dp = data();
+ if (dlen <= 2) {
+ x0 = relocInfo::short_data_at(0, dp, dlen);
+ x1 = relocInfo::short_data_at(1, dp, dlen);
+ } else {
+ assert(dlen <= 4, "too much data");
+ x0 = relocInfo::jint_data_at(0, dp, dlen);
+ x1 = relocInfo::jint_data_at(2, dp, dlen);
+ }
+ }
+
+ protected:
+ // platform-dependent utilities for decoding and patching instructions
+ void pd_set_data_value (address x, intptr_t off); // a set or mem-ref
+ address pd_call_destination (address orig_addr = NULL);
+ void pd_set_call_destination (address x);
+ void pd_swap_in_breakpoint (address x, short* instrs, int instrlen);
+ void pd_swap_out_breakpoint (address x, short* instrs, int instrlen);
+ static int pd_breakpoint_size ();
+
+ // this extracts the address of an address in the code stream instead of the reloc data
+ address* pd_address_in_code ();
+
+ // this extracts an address from the code stream instead of the reloc data
+ address pd_get_address_from_code ();
+
+ // these convert from byte offsets, to scaled offsets, to addresses
+ static jint scaled_offset(address x, address base) {
+ int byte_offset = x - base;
+ int offset = -byte_offset / relocInfo::addr_unit();
+ assert(address_from_scaled_offset(offset, base) == x, "just checkin'");
+ return offset;
+ }
+ static jint scaled_offset_null_special(address x, address base) {
+ // Some relocations treat offset=0 as meaning NULL.
+ // Handle this extra convention carefully.
+ if (x == NULL) return 0;
+ assert(x != base, "offset must not be zero");
+ return scaled_offset(x, base);
+ }
+ static address address_from_scaled_offset(jint offset, address base) {
+ int byte_offset = -( offset * relocInfo::addr_unit() );
+ return base + byte_offset;
+ }
+
+ // these convert between indexes and addresses in the runtime system
+ static int32_t runtime_address_to_index(address runtime_address);
+ static address index_to_runtime_address(int32_t index);
+
+ // helpers for mapping between old and new addresses after a move or resize
+ address old_addr_for(address newa, const CodeBuffer* src, CodeBuffer* dest);
+ address new_addr_for(address olda, const CodeBuffer* src, CodeBuffer* dest);
+ void normalize_address(address& addr, const CodeSection* dest, bool allow_other_sections = false);
+
+ public:
+ // accessors which only make sense for a bound Relocation
+ address addr() const { return binding()->addr(); }
+ CodeBlob* code() const { return binding()->code(); }
+ bool addr_in_const() const { return binding()->addr_in_const(); }
+ protected:
+ short* data() const { return binding()->data(); }
+ int datalen() const { return binding()->datalen(); }
+ int format() const { return binding()->format(); }
+
+ public:
+ virtual relocInfo::relocType type() { return relocInfo::none; }
+
+ // is it a call instruction?
+ virtual bool is_call() { return false; }
+
+ // is it a data movement instruction?
+ virtual bool is_data() { return false; }
+
+ // some relocations can compute their own values
+ virtual address value();
+
+ // all relocations are able to reassert their values
+ virtual void set_value(address x);
+
+ virtual void clear_inline_cache() { }
+
+ // This method assumes that all virtual/static (inline) caches are cleared (since for static_call_type and
+ // ic_call_type is not always posisition dependent (depending on the state of the cache)). However, this is
+ // probably a reasonable assumption, since empty caches simplifies code reloacation.
+ virtual void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest) { }
+
+ void print();
+};
+
+
+// certain inlines must be deferred until class Relocation is defined:
+
+inline RelocationHolder::RelocationHolder() {
+ // initialize the vtbl, just to keep things type-safe
+ new(*this) Relocation();
+}
+
+
+inline RelocationHolder::RelocationHolder(Relocation* r) {
+ // wordwise copy from r (ok if it copies garbage after r)
+ for (int i = 0; i < _relocbuf_size; i++) {
+ _relocbuf[i] = ((void**)r)[i];
+ }
+}
+
+
+relocInfo::relocType RelocationHolder::type() const {
+ return reloc()->type();
+}
+
+// A DataRelocation always points at a memory or load-constant instruction..
+// It is absolute on most machines, and the constant is split on RISCs.
+// The specific subtypes are oop, external_word, and internal_word.
+// By convention, the "value" does not include a separately reckoned "offset".
+class DataRelocation : public Relocation {
+ public:
+ bool is_data() { return true; }
+
+ // both target and offset must be computed somehow from relocation data
+ virtual int offset() { return 0; }
+ address value() = 0;
+ void set_value(address x) { set_value(x, offset()); }
+ void set_value(address x, intptr_t o) {
+ if (addr_in_const())
+ *(address*)addr() = x;
+ else
+ pd_set_data_value(x, o);
+ }
+
+ // The "o" (displacement) argument is relevant only to split relocations
+ // on RISC machines. In some CPUs (SPARC), the set-hi and set-lo ins'ns
+ // can encode more than 32 bits between them. This allows compilers to
+ // share set-hi instructions between addresses that differ by a small
+ // offset (e.g., different static variables in the same class).
+ // On such machines, the "x" argument to set_value on all set-lo
+ // instructions must be the same as the "x" argument for the
+ // corresponding set-hi instructions. The "o" arguments for the
+ // set-hi instructions are ignored, and must not affect the high-half
+ // immediate constant. The "o" arguments for the set-lo instructions are
+ // added into the low-half immediate constant, and must not overflow it.
+};
+
+// A CallRelocation always points at a call instruction.
+// It is PC-relative on most machines.
+class CallRelocation : public Relocation {
+ public:
+ bool is_call() { return true; }
+
+ address destination() { return pd_call_destination(); }
+ void set_destination(address x); // pd_set_call_destination
+
+ void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest);
+ address value() { return destination(); }
+ void set_value(address x) { set_destination(x); }
+};
+
+class oop_Relocation : public DataRelocation {
+ relocInfo::relocType type() { return relocInfo::oop_type; }
+
+ public:
+ // encode in one of these formats: [] [n] [n l] [Nn l] [Nn Ll]
+ // an oop in the CodeBlob's oop pool
+ static RelocationHolder spec(int oop_index, int offset = 0) {
+ assert(oop_index > 0, "must be a pool-resident oop");
+ RelocationHolder rh = newHolder();
+ new(rh) oop_Relocation(oop_index, offset);
+ return rh;
+ }
+ // an oop in the instruction stream
+ static RelocationHolder spec_for_immediate() {
+ const int oop_index = 0;
+ const int offset = 0; // if you want an offset, use the oop pool
+ RelocationHolder rh = newHolder();
+ new(rh) oop_Relocation(oop_index, offset);
+ return rh;
+ }
+
+ private:
+ jint _oop_index; // if > 0, index into CodeBlob::oop_at
+ jint _offset; // byte offset to apply to the oop itself
+
+ oop_Relocation(int oop_index, int offset) {
+ _oop_index = oop_index; _offset = offset;
+ }
+
+ friend class RelocIterator;
+ oop_Relocation() { }
+
+ public:
+ int oop_index() { return _oop_index; }
+ int offset() { return _offset; }
+
+ // data is packed in "2_ints" format: [i o] or [Ii Oo]
+ void pack_data_to(CodeSection* dest);
+ void unpack_data();
+
+ void fix_oop_relocation(); // reasserts oop value
+
+ address value() { return (address) *oop_addr(); }
+
+ bool oop_is_immediate() { return oop_index() == 0; }
+
+ oop* oop_addr(); // addr or &pool[jint_data]
+ oop oop_value(); // *oop_addr
+ // Note: oop_value transparently converts Universe::non_oop_word to NULL.
+};
+
+class virtual_call_Relocation : public CallRelocation {
+ relocInfo::relocType type() { return relocInfo::virtual_call_type; }
+
+ public:
+ // "first_oop" points to the first associated set-oop.
+ // The oop_limit helps find the last associated set-oop.
+ // (See comments at the top of this file.)
+ static RelocationHolder spec(address first_oop, address oop_limit = NULL) {
+ RelocationHolder rh = newHolder();
+ new(rh) virtual_call_Relocation(first_oop, oop_limit);
+ return rh;
+ }
+
+ virtual_call_Relocation(address first_oop, address oop_limit) {
+ _first_oop = first_oop; _oop_limit = oop_limit;
+ assert(first_oop != NULL, "first oop address must be specified");
+ }
+
+ private:
+ address _first_oop; // location of first set-oop instruction
+ address _oop_limit; // search limit for set-oop instructions
+
+ friend class RelocIterator;
+ virtual_call_Relocation() { }
+
+
+ public:
+ address first_oop();
+ address oop_limit();
+
+ // data is packed as scaled offsets in "2_ints" format: [f l] or [Ff Ll]
+ // oop_limit is set to 0 if the limit falls somewhere within the call.
+ // When unpacking, a zero oop_limit is taken to refer to the end of the call.
+ // (This has the effect of bringing in the call's delay slot on SPARC.)
+ void pack_data_to(CodeSection* dest);
+ void unpack_data();
+
+ void clear_inline_cache();
+
+ // Figure out where an ic_call is hiding, given a set-oop or call.
+ // Either ic_call or first_oop must be non-null; the other is deduced.
+ // Code if non-NULL must be the CodeBlob, else it is deduced.
+ // The address of the patchable oop is also deduced.
+ // The returned iterator will enumerate over the oops and the ic_call,
+ // as well as any other relocations that happen to be in that span of code.
+ // Recognize relevant set_oops with: oop_reloc()->oop_addr() == oop_addr.
+ static RelocIterator parse_ic(CodeBlob* &code, address &ic_call, address &first_oop, oop* &oop_addr, bool *is_optimized);
+};
+
+
+class opt_virtual_call_Relocation : public CallRelocation {
+ relocInfo::relocType type() { return relocInfo::opt_virtual_call_type; }
+
+ public:
+ static RelocationHolder spec() {
+ RelocationHolder rh = newHolder();
+ new(rh) opt_virtual_call_Relocation();
+ return rh;
+ }
+
+ private:
+ friend class RelocIterator;
+ opt_virtual_call_Relocation() { }
+
+ public:
+ void clear_inline_cache();
+
+ // find the matching static_stub
+ address static_stub();
+};
+
+
+class static_call_Relocation : public CallRelocation {
+ relocInfo::relocType type() { return relocInfo::static_call_type; }
+
+ public:
+ static RelocationHolder spec() {
+ RelocationHolder rh = newHolder();
+ new(rh) static_call_Relocation();
+ return rh;
+ }
+
+ private:
+ friend class RelocIterator;
+ static_call_Relocation() { }
+
+ public:
+ void clear_inline_cache();
+
+ // find the matching static_stub
+ address static_stub();
+};
+
+class static_stub_Relocation : public Relocation {
+ relocInfo::relocType type() { return relocInfo::static_stub_type; }
+
+ public:
+ static RelocationHolder spec(address static_call) {
+ RelocationHolder rh = newHolder();
+ new(rh) static_stub_Relocation(static_call);
+ return rh;
+ }
+
+ private:
+ address _static_call; // location of corresponding static_call
+
+ static_stub_Relocation(address static_call) {
+ _static_call = static_call;
+ }
+
+ friend class RelocIterator;
+ static_stub_Relocation() { }
+
+ public:
+ void clear_inline_cache();
+
+ address static_call() { return _static_call; }
+
+ // data is packed as a scaled offset in "1_int" format: [c] or [Cc]
+ void pack_data_to(CodeSection* dest);
+ void unpack_data();
+};
+
+class runtime_call_Relocation : public CallRelocation {
+ relocInfo::relocType type() { return relocInfo::runtime_call_type; }
+
+ public:
+ static RelocationHolder spec() {
+ RelocationHolder rh = newHolder();
+ new(rh) runtime_call_Relocation();
+ return rh;
+ }
+
+ private:
+ friend class RelocIterator;
+ runtime_call_Relocation() { }
+
+ public:
+};
+
+class external_word_Relocation : public DataRelocation {
+ relocInfo::relocType type() { return relocInfo::external_word_type; }
+
+ public:
+ static RelocationHolder spec(address target) {
+ assert(target != NULL, "must not be null");
+ RelocationHolder rh = newHolder();
+ new(rh) external_word_Relocation(target);
+ return rh;
+ }
+
+ // Use this one where all 32/64 bits of the target live in the code stream.
+ // The target must be an intptr_t, and must be absolute (not relative).
+ static RelocationHolder spec_for_immediate() {
+ RelocationHolder rh = newHolder();
+ new(rh) external_word_Relocation(NULL);
+ return rh;
+ }
+
+ private:
+ address _target; // address in runtime
+
+ external_word_Relocation(address target) {
+ _target = target;
+ }
+
+ friend class RelocIterator;
+ external_word_Relocation() { }
+
+ public:
+ // data is packed as a well-known address in "1_int" format: [a] or [Aa]
+ // The function runtime_address_to_index is used to turn full addresses
+ // to short indexes, if they are pre-registered by the stub mechanism.
+ // If the "a" value is 0 (i.e., _target is NULL), the address is stored
+ // in the code stream. See external_word_Relocation::target().
+ void pack_data_to(CodeSection* dest);
+ void unpack_data();
+
+ void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest);
+ address target(); // if _target==NULL, fetch addr from code stream
+ address value() { return target(); }
+};
+
+class internal_word_Relocation : public DataRelocation {
+ relocInfo::relocType type() { return relocInfo::internal_word_type; }
+
+ public:
+ static RelocationHolder spec(address target) {
+ assert(target != NULL, "must not be null");
+ RelocationHolder rh = newHolder();
+ new(rh) internal_word_Relocation(target);
+ return rh;
+ }
+
+ // use this one where all the bits of the target can fit in the code stream:
+ static RelocationHolder spec_for_immediate() {
+ RelocationHolder rh = newHolder();
+ new(rh) internal_word_Relocation(NULL);
+ return rh;
+ }
+
+ internal_word_Relocation(address target) {
+ _target = target;
+ _section = -1; // self-relative
+ }
+
+ protected:
+ address _target; // address in CodeBlob
+ int _section; // section providing base address, if any
+
+ friend class RelocIterator;
+ internal_word_Relocation() { }
+
+ // bit-width of LSB field in packed offset, if section >= 0
+ enum { section_width = 2 }; // must equal CodeBuffer::sect_bits
+
+ public:
+ // data is packed as a scaled offset in "1_int" format: [o] or [Oo]
+ // If the "o" value is 0 (i.e., _target is NULL), the offset is stored
+ // in the code stream. See internal_word_Relocation::target().
+ // If _section is not -1, it is appended to the low bits of the offset.
+ void pack_data_to(CodeSection* dest);
+ void unpack_data();
+
+ void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest);
+ address target(); // if _target==NULL, fetch addr from code stream
+ int section() { return _section; }
+ address value() { return target(); }
+};
+
+class section_word_Relocation : public internal_word_Relocation {
+ relocInfo::relocType type() { return relocInfo::section_word_type; }
+
+ public:
+ static RelocationHolder spec(address target, int section) {
+ RelocationHolder rh = newHolder();
+ new(rh) section_word_Relocation(target, section);
+ return rh;
+ }
+
+ section_word_Relocation(address target, int section) {
+ assert(target != NULL, "must not be null");
+ assert(section >= 0, "must be a valid section");
+ _target = target;
+ _section = section;
+ }
+
+ //void pack_data_to -- inherited
+ void unpack_data();
+
+ private:
+ friend class RelocIterator;
+ section_word_Relocation() { }
+};
+
+
+class poll_Relocation : public Relocation {
+ bool is_data() { return true; }
+ relocInfo::relocType type() { return relocInfo::poll_type; }
+};
+
+class poll_return_Relocation : public Relocation {
+ bool is_data() { return true; }
+ relocInfo::relocType type() { return relocInfo::poll_return_type; }
+};
+
+
+class breakpoint_Relocation : public Relocation {
+ relocInfo::relocType type() { return relocInfo::breakpoint_type; }
+
+ enum {
+ // attributes which affect the interpretation of the data:
+ removable_attr = 0x0010, // buffer [i...] allows for undoing the trap
+ internal_attr = 0x0020, // the target is an internal addr (local stub)
+ settable_attr = 0x0040, // the target is settable
+
+ // states which can change over time:
+ enabled_state = 0x0100, // breakpoint must be active in running code
+ active_state = 0x0200, // breakpoint instruction actually in code
+
+ kind_mask = 0x000F, // mask for extracting kind
+ high_bit = 0x4000 // extra bit which is always set
+ };
+
+ public:
+ enum {
+ // kinds:
+ initialization = 1,
+ safepoint = 2
+ };
+
+ // If target is NULL, 32 bits are reserved for a later set_target().
+ static RelocationHolder spec(int kind, address target = NULL, bool internal_target = false) {
+ RelocationHolder rh = newHolder();
+ new(rh) breakpoint_Relocation(kind, target, internal_target);
+ return rh;
+ }
+
+ private:
+ // We require every bits value to NOT to fit into relocInfo::datalen_width,
+ // because we are going to actually store state in the reloc, and so
+ // cannot allow it to be compressed (and hence copied by the iterator).
+
+ short _bits; // bit-encoded kind, attrs, & state
+ address _target;
+
+ breakpoint_Relocation(int kind, address target, bool internal_target);
+
+ friend class RelocIterator;
+ breakpoint_Relocation() { }
+
+ short bits() const { return _bits; }
+ short& live_bits() const { return data()[0]; }
+ short* instrs() const { return data() + datalen() - instrlen(); }
+ int instrlen() const { return removable() ? pd_breakpoint_size() : 0; }
+
+ void set_bits(short x) {
+ assert(live_bits() == _bits, "must be the only mutator of reloc info");
+ live_bits() = _bits = x;
+ }
+
+ public:
+ address target() const;
+ void set_target(address x);
+
+ int kind() const { return bits() & kind_mask; }
+ bool enabled() const { return (bits() & enabled_state) != 0; }
+ bool active() const { return (bits() & active_state) != 0; }
+ bool internal() const { return (bits() & internal_attr) != 0; }
+ bool removable() const { return (bits() & removable_attr) != 0; }
+ bool settable() const { return (bits() & settable_attr) != 0; }
+
+ void set_enabled(bool b); // to activate, you must also say set_active
+ void set_active(bool b); // actually inserts bpt (must be enabled 1st)
+
+ // data is packed as 16 bits, followed by the target (1 or 2 words), followed
+ // if necessary by empty storage for saving away original instruction bytes.
+ void pack_data_to(CodeSection* dest);
+ void unpack_data();
+
+ // during certain operations, breakpoints must be out of the way:
+ void fix_relocation_after_move(const CodeBuffer* src, CodeBuffer* dest) {
+ assert(!active(), "cannot perform relocation on enabled breakpoints");
+ }
+};
+
+
+// We know all the xxx_Relocation classes, so now we can define these:
+#define EACH_CASE(name) \
+inline name##_Relocation* RelocIterator::name##_reloc() { \
+ assert(type() == relocInfo::name##_type, "type must agree"); \
+ /* The purpose of the placed "new" is to re-use the same */ \
+ /* stack storage for each new iteration. */ \
+ name##_Relocation* r = new(_rh) name##_Relocation(); \
+ r->set_binding(this); \
+ r->name##_Relocation::unpack_data(); \
+ return r; \
+}
+APPLY_TO_RELOCATIONS(EACH_CASE);
+#undef EACH_CASE
+
+inline RelocIterator::RelocIterator(CodeBlob* cb, address begin, address limit) {
+ initialize(cb, begin, limit);
+}
+
+// if you are going to patch code, you should use this subclass of
+// RelocIterator
+class PatchingRelocIterator : public RelocIterator {
+ private:
+ RelocIterator _init_state;
+
+ void prepass(); // deactivates all breakpoints
+ void postpass(); // reactivates all enabled breakpoints
+
+ // do not copy these puppies; it would have unpredictable side effects
+ // these are private and have no bodies defined because they should not be called
+ PatchingRelocIterator(const RelocIterator&);
+ void operator=(const RelocIterator&);
+
+ public:
+ PatchingRelocIterator(CodeBlob* cb, address begin =NULL, address limit =NULL)
+ : RelocIterator(cb, begin, limit) { prepass(); }
+
+ ~PatchingRelocIterator() { postpass(); }
+};