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// Copyright (c) 1994-2006 Sun Microsystems Inc.
// All Rights Reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// - Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
//
// - Redistribution in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// - Neither the name of Sun Microsystems or the names of contributors may
// be used to endorse or promote products derived from this software without
// specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
// IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
// THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// The original source code covered by the above license above has been
// modified significantly by Google Inc.
// Copyright 2006-2009 the V8 project authors. All rights reserved.

#ifndef V8_ASSEMBLER_H_
#define V8_ASSEMBLER_H_

#include "runtime.h"
#include "top.h"
#include "token.h"
#include "objects.h"

namespace v8 {
namespace internal {


// -----------------------------------------------------------------------------
// Labels represent pc locations; they are typically jump or call targets.
// After declaration, a label can be freely used to denote known or (yet)
// unknown pc location. Assembler::bind() is used to bind a label to the
// current pc. A label can be bound only once.

class Label BASE_EMBEDDED {
public:
INLINE(Label()) { Unuse(); }
INLINE(~Label()) { ASSERT(!is_linked()); }

INLINE(void Unuse()) { pos_ = 0; }

INLINE(bool is_bound() const) { return pos_ < 0; }
INLINE(bool is_unused() const) { return pos_ == 0; }
INLINE(bool is_linked() const) { return pos_ > 0; }

// Returns the position of bound or linked labels. Cannot be used
// for unused labels.
int pos() const;

private:
// pos_ encodes both the binding state (via its sign)
// and the binding position (via its value) of a label.
//
// pos_ < 0 bound label, pos() returns the jump target position
// pos_ == 0 unused label
// pos_ > 0 linked label, pos() returns the last reference position
int pos_;

void bind_to(int pos) {
pos_ = -pos - 1;
ASSERT(is_bound());
}
void link_to(int pos) {
pos_ = pos + 1;
ASSERT(is_linked());
}

friend class Assembler;
friend class RegexpAssembler;
friend class Displacement;
friend class ShadowTarget;
friend class RegExpMacroAssemblerIrregexp;
};


// -----------------------------------------------------------------------------
// Relocation information


// Relocation information consists of the address (pc) of the datum
// to which the relocation information applies, the relocation mode
// (rmode), and an optional data field. The relocation mode may be
// "descriptive" and not indicate a need for relocation, but simply
// describe a property of the datum. Such rmodes are useful for GC
// and nice disassembly output.

class RelocInfo BASE_EMBEDDED {
public:
// The constant kNoPosition is used with the collecting of source positions
// in the relocation information. Two types of source positions are collected
// "position" (RelocMode position) and "statement position" (RelocMode
// statement_position). The "position" is collected at places in the source
// code which are of interest when making stack traces to pin-point the source
// location of a stack frame as close as possible. The "statement position" is
// collected at the beginning at each statement, and is used to indicate
// possible break locations. kNoPosition is used to indicate an
// invalid/uninitialized position value.
static const int kNoPosition = -1;

enum Mode {
// Please note the order is important (see IsCodeTarget, IsGCRelocMode).
CONSTRUCT_CALL, // code target that is a call to a JavaScript constructor.
CODE_TARGET_CONTEXT, // Code target used for contextual loads.
DEBUG_BREAK, // Code target for the debugger statement.
CODE_TARGET, // Code target which is not any of the above.
EMBEDDED_OBJECT,

// Everything after runtime_entry (inclusive) is not GC'ed.
RUNTIME_ENTRY,
JS_RETURN, // Marks start of the ExitJSFrame code.
COMMENT,
POSITION, // See comment for kNoPosition above.
STATEMENT_POSITION, // See comment for kNoPosition above.
DEBUG_BREAK_SLOT, // Additional code inserted for debug break slot.
EXTERNAL_REFERENCE, // The address of an external C++ function.
INTERNAL_REFERENCE, // An address inside the same function.

// add more as needed
// Pseudo-types
NUMBER_OF_MODES, // must be no greater than 14 - see RelocInfoWriter
NONE, // never recorded
LAST_CODE_ENUM = CODE_TARGET,
LAST_GCED_ENUM = EMBEDDED_OBJECT
};


RelocInfo() {}
RelocInfo(byte* pc, Mode rmode, intptr_t data)
: pc_(pc), rmode_(rmode), data_(data) {
}

static inline bool IsConstructCall(Mode mode) {
return mode == CONSTRUCT_CALL;
}
static inline bool IsCodeTarget(Mode mode) {
return mode <= LAST_CODE_ENUM;
}
// Is the relocation mode affected by GC?
static inline bool IsGCRelocMode(Mode mode) {
return mode <= LAST_GCED_ENUM;
}
static inline bool IsJSReturn(Mode mode) {
return mode == JS_RETURN;
}
static inline bool IsComment(Mode mode) {
return mode == COMMENT;
}
static inline bool IsPosition(Mode mode) {
return mode == POSITION || mode == STATEMENT_POSITION;
}
static inline bool IsStatementPosition(Mode mode) {
return mode == STATEMENT_POSITION;
}
static inline bool IsExternalReference(Mode mode) {
return mode == EXTERNAL_REFERENCE;
}
static inline bool IsInternalReference(Mode mode) {
return mode == INTERNAL_REFERENCE;
}
static inline bool IsDebugBreakSlot(Mode mode) {
return mode == DEBUG_BREAK_SLOT;
}
static inline int ModeMask(Mode mode) { return 1 << mode; }

// Accessors
byte* pc() const { return pc_; }
void set_pc(byte* pc) { pc_ = pc; }
Mode rmode() const { return rmode_; }
intptr_t data() const { return data_; }

// Apply a relocation by delta bytes
INLINE(void apply(intptr_t delta));

// Is the pointer this relocation info refers to coded like a plain pointer
// or is it strange in some way (eg relative or patched into a series of
// instructions).
bool IsCodedSpecially();

// Read/modify the code target in the branch/call instruction
// this relocation applies to;
// can only be called if IsCodeTarget(rmode_) || rmode_ == RUNTIME_ENTRY
INLINE(Address target_address());
INLINE(void set_target_address(Address target));
INLINE(Object* target_object());
INLINE(Handle<Object> target_object_handle(Assembler* origin));
INLINE(Object** target_object_address());
INLINE(void set_target_object(Object* target));

// Read the address of the word containing the target_address in an
// instruction stream. What this means exactly is architecture-independent.
// The only architecture-independent user of this function is the serializer.
// The serializer uses it to find out how many raw bytes of instruction to
// output before the next target. Architecture-independent code shouldn't
// dereference the pointer it gets back from this.
INLINE(Address target_address_address());
// This indicates how much space a target takes up when deserializing a code
// stream. For most architectures this is just the size of a pointer. For
// an instruction like movw/movt where the target bits are mixed into the
// instruction bits the size of the target will be zero, indicating that the
// serializer should not step forwards in memory after a target is resolved
// and written. In this case the target_address_address function above
// should return the end of the instructions to be patched, allowing the
// deserializer to deserialize the instructions as raw bytes and put them in
// place, ready to be patched with the target.
INLINE(int target_address_size());

// Read/modify the reference in the instruction this relocation
// applies to; can only be called if rmode_ is external_reference
INLINE(Address* target_reference_address());

// Read/modify the address of a call instruction. This is used to relocate
// the break points where straight-line code is patched with a call
// instruction.
INLINE(Address call_address());
INLINE(void set_call_address(Address target));
INLINE(Object* call_object());
INLINE(Object** call_object_address());
INLINE(void set_call_object(Object* target));

inline void Visit(ObjectVisitor* v);

// Patch the code with some other code.
void PatchCode(byte* instructions, int instruction_count);

// Patch the code with a call.
void PatchCodeWithCall(Address target, int guard_bytes);

// Check whether this return sequence has been patched
// with a call to the debugger.
INLINE(bool IsPatchedReturnSequence());

// Check whether this debug break slot has been patched with a call to the
// debugger.
INLINE(bool IsPatchedDebugBreakSlotSequence());

#ifdef ENABLE_DISASSEMBLER
// Printing
static const char* RelocModeName(Mode rmode);
void Print();
#endif // ENABLE_DISASSEMBLER
#ifdef DEBUG
// Debugging
void Verify();
#endif

static const int kCodeTargetMask = (1 << (LAST_CODE_ENUM + 1)) - 1;
static const int kPositionMask = 1 << POSITION | 1 << STATEMENT_POSITION;
static const int kDebugMask = kPositionMask | 1 << COMMENT;
static const int kApplyMask; // Modes affected by apply. Depends on arch.

private:
// On ARM, note that pc_ is the address of the constant pool entry
// to be relocated and not the address of the instruction
// referencing the constant pool entry (except when rmode_ ==
// comment).
byte* pc_;
Mode rmode_;
intptr_t data_;
friend class RelocIterator;
};


// RelocInfoWriter serializes a stream of relocation info. It writes towards
// lower addresses.
class RelocInfoWriter BASE_EMBEDDED {
public:
RelocInfoWriter() : pos_(NULL), last_pc_(NULL), last_data_(0) {}
RelocInfoWriter(byte* pos, byte* pc) : pos_(pos), last_pc_(pc),
last_data_(0) {}

byte* pos() const { return pos_; }
byte* last_pc() const { return last_pc_; }

void Write(const RelocInfo* rinfo);

// Update the state of the stream after reloc info buffer
// and/or code is moved while the stream is active.
void Reposition(byte* pos, byte* pc) {
pos_ = pos;
last_pc_ = pc;
}

// Max size (bytes) of a written RelocInfo. Longest encoding is
// ExtraTag, VariableLengthPCJump, ExtraTag, pc_delta, ExtraTag, data_delta.
// On ia32 and arm this is 1 + 4 + 1 + 1 + 1 + 4 = 12.
// On x64 this is 1 + 4 + 1 + 1 + 1 + 8 == 16;
// Here we use the maximum of the two.
static const int kMaxSize = 16;

private:
inline uint32_t WriteVariableLengthPCJump(uint32_t pc_delta);
inline void WriteTaggedPC(uint32_t pc_delta, int tag);
inline void WriteExtraTaggedPC(uint32_t pc_delta, int extra_tag);
inline void WriteExtraTaggedData(intptr_t data_delta, int top_tag);
inline void WriteTaggedData(intptr_t data_delta, int tag);
inline void WriteExtraTag(int extra_tag, int top_tag);

byte* pos_;
byte* last_pc_;
intptr_t last_data_;
DISALLOW_COPY_AND_ASSIGN(RelocInfoWriter);
};


// A RelocIterator iterates over relocation information.
// Typical use:
//
// for (RelocIterator it(code); !it.done(); it.next()) {
// // do something with it.rinfo() here
// }
//
// A mask can be specified to skip unwanted modes.
class RelocIterator: public Malloced {
public:
// Create a new iterator positioned at
// the beginning of the reloc info.
// Relocation information with mode k is included in the
// iteration iff bit k of mode_mask is set.
explicit RelocIterator(Code* code, int mode_mask = -1);
explicit RelocIterator(const CodeDesc& desc, int mode_mask = -1);

// Iteration
bool done() const { return done_; }
void next();

// Return pointer valid until next next().
RelocInfo* rinfo() {
ASSERT(!done());
return &rinfo_;
}

private:
// Advance* moves the position before/after reading.
// *Read* reads from current byte(s) into rinfo_.
// *Get* just reads and returns info on current byte.
void Advance(int bytes = 1) { pos_ -= bytes; }
int AdvanceGetTag();
int GetExtraTag();
int GetTopTag();
void ReadTaggedPC();
void AdvanceReadPC();
void AdvanceReadData();
void AdvanceReadVariableLengthPCJump();
int GetPositionTypeTag();
void ReadTaggedData();

static RelocInfo::Mode DebugInfoModeFromTag(int tag);

// If the given mode is wanted, set it in rinfo_ and return true.
// Else return false. Used for efficiently skipping unwanted modes.
bool SetMode(RelocInfo::Mode mode) {
return (mode_mask_ & 1 << mode) ? (rinfo_.rmode_ = mode, true) : false;
}

byte* pos_;
byte* end_;
RelocInfo rinfo_;
bool done_;
int mode_mask_;
DISALLOW_COPY_AND_ASSIGN(RelocIterator);
};


//------------------------------------------------------------------------------
// External function

//----------------------------------------------------------------------------
class IC_Utility;
class SCTableReference;
#ifdef ENABLE_DEBUGGER_SUPPORT
class Debug_Address;
#endif


typedef void* ExternalReferenceRedirector(void* original, bool fp_return);


// An ExternalReference represents a C++ address used in the generated
// code. All references to C++ functions and variables must be encapsulated in
// an ExternalReference instance. This is done in order to track the origin of
// all external references in the code so that they can be bound to the correct
// addresses when deserializing a heap.
class ExternalReference BASE_EMBEDDED {
public:
explicit ExternalReference(Builtins::CFunctionId id);

explicit ExternalReference(ApiFunction* ptr);

explicit ExternalReference(Builtins::Name name);

explicit ExternalReference(Runtime::FunctionId id);

explicit ExternalReference(Runtime::Function* f);

explicit ExternalReference(const IC_Utility& ic_utility);

#ifdef ENABLE_DEBUGGER_SUPPORT
explicit ExternalReference(const Debug_Address& debug_address);
#endif

explicit ExternalReference(StatsCounter* counter);

explicit ExternalReference(Top::AddressId id);

explicit ExternalReference(const SCTableReference& table_ref);

// One-of-a-kind references. These references are not part of a general
// pattern. This means that they have to be added to the
// ExternalReferenceTable in serialize.cc manually.

static ExternalReference perform_gc_function();
static ExternalReference fill_heap_number_with_random_function();
static ExternalReference random_uint32_function();
static ExternalReference transcendental_cache_array_address();

// Static data in the keyed lookup cache.
static ExternalReference keyed_lookup_cache_keys();
static ExternalReference keyed_lookup_cache_field_offsets();

// Static variable Factory::the_hole_value.location()
static ExternalReference the_hole_value_location();

// Static variable Heap::roots_address()
static ExternalReference roots_address();

// Static variable StackGuard::address_of_jslimit()
static ExternalReference address_of_stack_limit();

// Static variable StackGuard::address_of_real_jslimit()
static ExternalReference address_of_real_stack_limit();

// Static variable RegExpStack::limit_address()
static ExternalReference address_of_regexp_stack_limit();

// Static variables for RegExp.
static ExternalReference address_of_static_offsets_vector();
static ExternalReference address_of_regexp_stack_memory_address();
static ExternalReference address_of_regexp_stack_memory_size();

// Static variable Heap::NewSpaceStart()
static ExternalReference new_space_start();
static ExternalReference new_space_mask();
static ExternalReference heap_always_allocate_scope_depth();

// Used for fast allocation in generated code.
static ExternalReference new_space_allocation_top_address();
static ExternalReference new_space_allocation_limit_address();

static ExternalReference double_fp_operation(Token::Value operation);
static ExternalReference compare_doubles();

static ExternalReference handle_scope_extensions_address();
static ExternalReference handle_scope_next_address();
static ExternalReference handle_scope_limit_address();

static ExternalReference scheduled_exception_address();

Address address() const {return reinterpret_cast<Address>(address_);}

#ifdef ENABLE_DEBUGGER_SUPPORT
// Function Debug::Break()
static ExternalReference debug_break();

// Used to check if single stepping is enabled in generated code.
static ExternalReference debug_step_in_fp_address();
#endif

#ifndef V8_INTERPRETED_REGEXP
// C functions called from RegExp generated code.

// Function NativeRegExpMacroAssembler::CaseInsensitiveCompareUC16()
static ExternalReference re_case_insensitive_compare_uc16();

// Function RegExpMacroAssembler*::CheckStackGuardState()
static ExternalReference re_check_stack_guard_state();

// Function NativeRegExpMacroAssembler::GrowStack()
static ExternalReference re_grow_stack();

// byte NativeRegExpMacroAssembler::word_character_bitmap
static ExternalReference re_word_character_map();

#endif

// This lets you register a function that rewrites all external references.
// Used by the ARM simulator to catch calls to external references.
static void set_redirector(ExternalReferenceRedirector* redirector) {
ASSERT(redirector_ == NULL); // We can't stack them.
redirector_ = redirector;
}

private:
explicit ExternalReference(void* address)
: address_(address) {}

static ExternalReferenceRedirector* redirector_;

static void* Redirect(void* address, bool fp_return = false) {
if (redirector_ == NULL) return address;
void* answer = (*redirector_)(address, fp_return);
return answer;
}

static void* Redirect(Address address_arg, bool fp_return = false) {
void* address = reinterpret_cast<void*>(address_arg);
void* answer = (redirector_ == NULL) ?
address :
(*redirector_)(address, fp_return);
return answer;
}

void* address_;
};


// -----------------------------------------------------------------------------
// Utility functions

static inline bool is_intn(int x, int n) {
return -(1 << (n-1)) <= x && x < (1 << (n-1));
}

static inline bool is_int8(int x) { return is_intn(x, 8); }
static inline bool is_int16(int x) { return is_intn(x, 16); }
static inline bool is_int18(int x) { return is_intn(x, 18); }
static inline bool is_int24(int x) { return is_intn(x, 24); }

static inline bool is_uintn(int x, int n) {
return (x & -(1 << n)) == 0;
}

static inline bool is_uint2(int x) { return is_uintn(x, 2); }
static inline bool is_uint3(int x) { return is_uintn(x, 3); }
static inline bool is_uint4(int x) { return is_uintn(x, 4); }
static inline bool is_uint5(int x) { return is_uintn(x, 5); }
static inline bool is_uint6(int x) { return is_uintn(x, 6); }
static inline bool is_uint8(int x) { return is_uintn(x, 8); }
static inline bool is_uint10(int x) { return is_uintn(x, 10); }
static inline bool is_uint12(int x) { return is_uintn(x, 12); }
static inline bool is_uint16(int x) { return is_uintn(x, 16); }
static inline bool is_uint24(int x) { return is_uintn(x, 24); }
static inline bool is_uint26(int x) { return is_uintn(x, 26); }
static inline bool is_uint28(int x) { return is_uintn(x, 28); }

static inline int NumberOfBitsSet(uint32_t x) {
unsigned int num_bits_set;
for (num_bits_set = 0; x; x >>= 1) {
num_bits_set += x & 1;
}
return num_bits_set;
}

} } // namespace v8::internal

#endif // V8_ASSEMBLER_H_

Change log

r4820 by sgje...@chromium.org on Jun 8, 2010   Diff
More precise break points and stepping
when debugging

Added support for more precise break
points when debugging and stepping. To
achieve that additional nop instructions
are inserted where breaking would
otherwise be impossible. The number of nop
instructions inserted are sufficient to
make place for patching with a call to a
debug break code stub. On Intel that is 5
nop's for 32-bit and 13 for 64-bit. Om ARM
...
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Project members, sign in to write a code review

Older revisions

r4721 by erik.corry on May 26, 2010   Diff
The way reloc entries are visited by
the ObjectVisitor is architecture
dependent, so we push it down to the
architecture dependent files.
Currently all architectures visit in
...
r4687 by erik.corry on May 20, 2010   Diff
Orthogonalize the byte codes used for
the snapshot so that
the issue of how the pointee is found
and how the pointer
is encoded are separated out.  This
...
r4672 by erik.corry on May 18, 2010   Diff
Remove unused relocation mode.
Review URL:
http://codereview.chromium.org/2136012
All revisions of this file

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