src/arm/macro-assembler-arm.h

// Copyright 2006-2009 the V8 project authors. 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.
//     * Redistributions 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.
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//       contributors may be used to endorse or promote products derived
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//
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#ifndef V8_ARM_MACRO_ASSEMBLER_ARM_H_
#define V8_ARM_MACRO_ASSEMBLER_ARM_H_

#include "assembler.h"

namespace v8 {
namespace internal {

// ----------------------------------------------------------------------------
// Static helper functions

// Generate a MemOperand for loading a field from an object.
static inline MemOperand FieldMemOperand(Register object, int offset) {
  return MemOperand(object, offset - kHeapObjectTag);
}


// Give alias names to registers
const Register cp = { 8 };  // JavaScript context pointer
const Register roots = { 10 };  // Roots array pointer.

enum InvokeJSFlags {
  CALL_JS,
  JUMP_JS
};


// Flags used for the AllocateInNewSpace functions.
enum AllocationFlags {
  // No special flags.
  NO_ALLOCATION_FLAGS = 0,
  // Return the pointer to the allocated already tagged as a heap object.
  TAG_OBJECT = 1 << 0,
  // The content of the result register already contains the allocation top in
  // new space.
  RESULT_CONTAINS_TOP = 1 << 1,
  // Specify that the requested size of the space to allocate is specified in
  // words instead of bytes.
  SIZE_IN_WORDS = 1 << 2
};


// MacroAssembler implements a collection of frequently used macros.
class MacroAssembler: public Assembler {
 public:
  MacroAssembler(void* buffer, int size);

  // Jump, Call, and Ret pseudo instructions implementing inter-working.
  void Jump(Register target, Condition cond = al);
  void Jump(byte* target, RelocInfo::Mode rmode, Condition cond = al);
  void Jump(Handle<Code> code, RelocInfo::Mode rmode, Condition cond = al);
  void Call(Register target, Condition cond = al);
  void Call(byte* target, RelocInfo::Mode rmode, Condition cond = al);
  void Call(Handle<Code> code, RelocInfo::Mode rmode, Condition cond = al);
  void Ret(Condition cond = al);

  // Emit code to discard a non-negative number of pointer-sized elements
  // from the stack, clobbering only the sp register.
  void Drop(int count, Condition cond = al);


  // Swap two registers.  If the scratch register is omitted then a slightly
  // less efficient form using xor instead of mov is emitted.
  void Swap(Register reg1,
            Register reg2,
            Register scratch = no_reg,
            Condition cond = al);


  void And(Register dst, Register src1, const Operand& src2,
           Condition cond = al);
  void Ubfx(Register dst, Register src, int lsb, int width,
            Condition cond = al);
  void Sbfx(Register dst, Register src, int lsb, int width,
            Condition cond = al);
  void Bfc(Register dst, int lsb, int width, Condition cond = al);

  void Call(Label* target);
  void Move(Register dst, Handle<Object> value);
  // May do nothing if the registers are identical.
  void Move(Register dst, Register src);
  // Jumps to the label at the index given by the Smi in "index".
  void SmiJumpTable(Register index, Vector<Label*> targets);
  // Load an object from the root table.
  void LoadRoot(Register destination,
                Heap::RootListIndex index,
                Condition cond = al);
  // Store an object to the root table.
  void StoreRoot(Register source,
                 Heap::RootListIndex index,
                 Condition cond = al);


  // Check if object is in new space.
  // scratch can be object itself, but it will be clobbered.
  void InNewSpace(Register object,
                  Register scratch,
                  Condition cc,  // eq for new space, ne otherwise
                  Label* branch);


  // For the page containing |object| mark the region covering [object+offset]
  // dirty. The object address must be in the first 8K of an allocated page.
  void RecordWriteHelper(Register object,
                         Operand offset,
                         Register scratch0,
                         Register scratch1);

  // For the page containing |object| mark the region covering [object+offset]
  // dirty. The object address must be in the first 8K of an allocated page.
  // The 'scratch' registers are used in the implementation and all 3 registers
  // are clobbered by the operation, as well as the ip register.
  void RecordWrite(Register object,
                   Operand offset,
                   Register scratch0,
                   Register scratch1);

  // Push two registers.  Pushes leftmost register first (to highest address).
  void Push(Register src1, Register src2, Condition cond = al) {
    ASSERT(!src1.is(src2));
    if (src1.code() > src2.code()) {
      stm(db_w, sp, src1.bit() | src2.bit(), cond);
    } else {
      str(src1, MemOperand(sp, 4, NegPreIndex), cond);
      str(src2, MemOperand(sp, 4, NegPreIndex), cond);
    }
  }

  // Push three registers.  Pushes leftmost register first (to highest address).
  void Push(Register src1, Register src2, Register src3, Condition cond = al) {
    ASSERT(!src1.is(src2));
    ASSERT(!src2.is(src3));
    ASSERT(!src1.is(src3));
    if (src1.code() > src2.code()) {
      if (src2.code() > src3.code()) {
        stm(db_w, sp, src1.bit() | src2.bit() | src3.bit(), cond);
      } else {
        stm(db_w, sp, src1.bit() | src2.bit(), cond);
        str(src3, MemOperand(sp, 4, NegPreIndex), cond);
      }
    } else {
      str(src1, MemOperand(sp, 4, NegPreIndex), cond);
      Push(src2, src3, cond);
    }
  }

  // Push four registers.  Pushes leftmost register first (to highest address).
  void Push(Register src1, Register src2,
            Register src3, Register src4, Condition cond = al) {
    ASSERT(!src1.is(src2));
    ASSERT(!src2.is(src3));
    ASSERT(!src1.is(src3));
    ASSERT(!src1.is(src4));
    ASSERT(!src2.is(src4));
    ASSERT(!src3.is(src4));
    if (src1.code() > src2.code()) {
      if (src2.code() > src3.code()) {
        if (src3.code() > src4.code()) {
          stm(db_w,
              sp,
              src1.bit() | src2.bit() | src3.bit() | src4.bit(),
              cond);
        } else {
          stm(db_w, sp, src1.bit() | src2.bit() | src3.bit(), cond);
          str(src4, MemOperand(sp, 4, NegPreIndex), cond);
        }
      } else {
        stm(db_w, sp, src1.bit() | src2.bit(), cond);
        Push(src3, src4, cond);
      }
    } else {
      str(src1, MemOperand(sp, 4, NegPreIndex), cond);
      Push(src2, src3, src4, cond);
    }
  }

  // Load two consecutive registers with two consecutive memory locations.
  void Ldrd(Register dst1,
            Register dst2,
            const MemOperand& src,
            Condition cond = al);

  // Store two consecutive registers to two consecutive memory locations.
  void Strd(Register src1,
            Register src2,
            const MemOperand& dst,
            Condition cond = al);

  // ---------------------------------------------------------------------------
  // Stack limit support

  void StackLimitCheck(Label* on_stack_limit_hit);

  // ---------------------------------------------------------------------------
  // Activation frames

  void EnterInternalFrame() { EnterFrame(StackFrame::INTERNAL); }
  void LeaveInternalFrame() { LeaveFrame(StackFrame::INTERNAL); }

  void EnterConstructFrame() { EnterFrame(StackFrame::CONSTRUCT); }
  void LeaveConstructFrame() { LeaveFrame(StackFrame::CONSTRUCT); }

  // Enter specific kind of exit frame; either normal or debug mode.
  // Expects the number of arguments in register r0 and
  // the builtin function to call in register r1. Exits with argc in
  // r4, argv in r6, and and the builtin function to call in r5.
  void EnterExitFrame(ExitFrame::Mode mode);

  // Leave the current exit frame. Expects the return value in r0.
  void LeaveExitFrame(ExitFrame::Mode mode);

  // Get the actual activation frame alignment for target environment.
  static int ActivationFrameAlignment();

  void LoadContext(Register dst, int context_chain_length);

  // ---------------------------------------------------------------------------
  // JavaScript invokes

  // Invoke the JavaScript function code by either calling or jumping.
  void InvokeCode(Register code,
                  const ParameterCount& expected,
                  const ParameterCount& actual,
                  InvokeFlag flag);

  void InvokeCode(Handle<Code> code,
                  const ParameterCount& expected,
                  const ParameterCount& actual,
                  RelocInfo::Mode rmode,
                  InvokeFlag flag);

  // Invoke the JavaScript function in the given register. Changes the
  // current context to the context in the function before invoking.
  void InvokeFunction(Register function,
                      const ParameterCount& actual,
                      InvokeFlag flag);

  void InvokeFunction(JSFunction* function,
                      const ParameterCount& actual,
                      InvokeFlag flag);


#ifdef ENABLE_DEBUGGER_SUPPORT
  // ---------------------------------------------------------------------------
  // Debugger Support

  void SaveRegistersToMemory(RegList regs);
  void RestoreRegistersFromMemory(RegList regs);
  void CopyRegistersFromMemoryToStack(Register base, RegList regs);
  void CopyRegistersFromStackToMemory(Register base,
                                      Register scratch,
                                      RegList regs);
  void DebugBreak();
#endif

  // ---------------------------------------------------------------------------
  // Exception handling

  // Push a new try handler and link into try handler chain.
  // The return address must be passed in register lr.
  // On exit, r0 contains TOS (code slot).
  void PushTryHandler(CodeLocation try_location, HandlerType type);

  // Unlink the stack handler on top of the stack from the try handler chain.
  // Must preserve the result register.
  void PopTryHandler();

  // ---------------------------------------------------------------------------
  // Inline caching support

  // Generates code that verifies that the maps of objects in the
  // prototype chain of object hasn't changed since the code was
  // generated and branches to the miss label if any map has. If
  // necessary the function also generates code for security check
  // in case of global object holders. The scratch and holder
  // registers are always clobbered, but the object register is only
  // clobbered if it the same as the holder register. The function
  // returns a register containing the holder - either object_reg or
  // holder_reg.
  // The function can optionally (when save_at_depth !=
  // kInvalidProtoDepth) save the object at the given depth by moving
  // it to [sp].
  Register CheckMaps(JSObject* object, Register object_reg,
                     JSObject* holder, Register holder_reg,
                     Register scratch,
                     int save_at_depth,
                     Label* miss);

  // Generate code for checking access rights - used for security checks
  // on access to global objects across environments. The holder register
  // is left untouched, whereas both scratch registers are clobbered.
  void CheckAccessGlobalProxy(Register holder_reg,
                              Register scratch,
                              Label* miss);


  // ---------------------------------------------------------------------------
  // Allocation support

  // Allocate an object in new space. The object_size is specified in words (not
  // bytes). If the new space is exhausted control continues at the gc_required
  // label. The allocated object is returned in result. If the flag
  // tag_allocated_object is true the result is tagged as as a heap object. All
  // registers are clobbered also when control continues at the gc_required
  // label.
  void AllocateInNewSpace(int object_size,
                          Register result,
                          Register scratch1,
                          Register scratch2,
                          Label* gc_required,
                          AllocationFlags flags);
  void AllocateInNewSpace(Register object_size,
                          Register result,
                          Register scratch1,
                          Register scratch2,
                          Label* gc_required,
                          AllocationFlags flags);

  // Undo allocation in new space. The object passed and objects allocated after
  // it will no longer be allocated. The caller must make sure that no pointers
  // are left to the object(s) no longer allocated as they would be invalid when
  // allocation is undone.
  void UndoAllocationInNewSpace(Register object, Register scratch);


  void AllocateTwoByteString(Register result,
                             Register length,
                             Register scratch1,
                             Register scratch2,
                             Register scratch3,
                             Label* gc_required);
  void AllocateAsciiString(Register result,
                           Register length,
                           Register scratch1,
                           Register scratch2,
                           Register scratch3,
                           Label* gc_required);
  void AllocateTwoByteConsString(Register result,
                                 Register length,
                                 Register scratch1,
                                 Register scratch2,
                                 Label* gc_required);
  void AllocateAsciiConsString(Register result,
                               Register length,
                               Register scratch1,
                               Register scratch2,
                               Label* gc_required);

  // Allocates a heap number or jumps to the gc_required label if the young
  // space is full and a scavenge is needed. All registers are clobbered also
  // when control continues at the gc_required label.
  void AllocateHeapNumber(Register result,
                          Register scratch1,
                          Register scratch2,
                          Register heap_number_map,
                          Label* gc_required);

  // ---------------------------------------------------------------------------
  // Support functions.

  // Try to get function prototype of a function and puts the value in
  // the result register. Checks that the function really is a
  // function and jumps to the miss label if the fast checks fail. The
  // function register will be untouched; the other registers may be
  // clobbered.
  void TryGetFunctionPrototype(Register function,
                               Register result,
                               Register scratch,
                               Label* miss);

  // Compare object type for heap object.  heap_object contains a non-Smi
  // whose object type should be compared with the given type.  This both
  // sets the flags and leaves the object type in the type_reg register.
  // It leaves the map in the map register (unless the type_reg and map register
  // are the same register).  It leaves the heap object in the heap_object
  // register unless the heap_object register is the same register as one of the
  // other registers.
  void CompareObjectType(Register heap_object,
                         Register map,
                         Register type_reg,
                         InstanceType type);

  // Compare instance type in a map.  map contains a valid map object whose
  // object type should be compared with the given type.  This both
  // sets the flags and leaves the object type in the type_reg register.  It
  // leaves the heap object in the heap_object register unless the heap_object
  // register is the same register as type_reg.
  void CompareInstanceType(Register map,
                           Register type_reg,
                           InstanceType type);


  // Check if the map of an object is equal to a specified map (either
  // given directly or as an index into the root list) and branch to
  // label if not. Skip the smi check if not required (object is known
  // to be a heap object)
  void CheckMap(Register obj,
                Register scratch,
                Handle<Map> map,
                Label* fail,
                bool is_heap_object);

  void CheckMap(Register obj,
                Register scratch,
                Heap::RootListIndex index,
                Label* fail,
                bool is_heap_object);


  // Load and check the instance type of an object for being a string.
  // Loads the type into the second argument register.
  // Returns a condition that will be enabled if the object was a string.
  Condition IsObjectStringType(Register obj,
                               Register type) {
    ldr(type, FieldMemOperand(obj, HeapObject::kMapOffset));
    ldrb(type, FieldMemOperand(type, Map::kInstanceTypeOffset));
    tst(type, Operand(kIsNotStringMask));
    ASSERT_EQ(0, kStringTag);
    return eq;
  }


  inline void BranchOnSmi(Register value, Label* smi_label) {
    tst(value, Operand(kSmiTagMask));
    b(eq, smi_label);
  }

  inline void BranchOnNotSmi(Register value, Label* not_smi_label) {
    tst(value, Operand(kSmiTagMask));
    b(ne, not_smi_label);
  }

  // Generates code for reporting that an illegal operation has
  // occurred.
  void IllegalOperation(int num_arguments);

  // Get the number of least significant bits from a register
  void GetLeastBitsFromSmi(Register dst, Register src, int num_least_bits);

  // Uses VFP instructions to Convert a Smi to a double.
  void IntegerToDoubleConversionWithVFP3(Register inReg,
                                         Register outHighReg,
                                         Register outLowReg);

  // Count leading zeros in a 32 bit word.  On ARM5 and later it uses the clz
  // instruction.  On pre-ARM5 hardware this routine gives the wrong answer
  // for 0 (31 instead of 32).
  void CountLeadingZeros(Register source,
                         Register scratch,
                         Register zeros);

  // ---------------------------------------------------------------------------
  // Runtime calls

  // Call a code stub.
  void CallStub(CodeStub* stub, Condition cond = al);

  // Call a code stub.
  void TailCallStub(CodeStub* stub, Condition cond = al);

  // Return from a code stub after popping its arguments.
  void StubReturn(int argc);

  // Call a runtime routine.
  void CallRuntime(Runtime::Function* f, int num_arguments);

  // Convenience function: Same as above, but takes the fid instead.
  void CallRuntime(Runtime::FunctionId fid, int num_arguments);

  // Convenience function: call an external reference.
  void CallExternalReference(const ExternalReference& ext,
                             int num_arguments);

  // Tail call of a runtime routine (jump).
  // Like JumpToExternalReference, but also takes care of passing the number
  // of parameters.
  void TailCallExternalReference(const ExternalReference& ext,
                                 int num_arguments,
                                 int result_size);

  // Convenience function: tail call a runtime routine (jump).
  void TailCallRuntime(Runtime::FunctionId fid,
                       int num_arguments,
                       int result_size);

  // Before calling a C-function from generated code, align arguments on stack.
  // After aligning the frame, non-register arguments must be stored in
  // sp[0], sp[4], etc., not pushed. The argument count assumes all arguments
  // are word sized.
  // Some compilers/platforms require the stack to be aligned when calling
  // C++ code.
  // Needs a scratch register to do some arithmetic. This register will be
  // trashed.
  void PrepareCallCFunction(int num_arguments, Register scratch);

  // Calls a C function and cleans up the space for arguments allocated
  // by PrepareCallCFunction. The called function is not allowed to trigger a
  // garbage collection, since that might move the code and invalidate the
  // return address (unless this is somehow accounted for by the called
  // function).
  void CallCFunction(ExternalReference function, int num_arguments);
  void CallCFunction(Register function, int num_arguments);

  // Jump to a runtime routine.
  void JumpToExternalReference(const ExternalReference& builtin);

  // Invoke specified builtin JavaScript function. Adds an entry to
  // the unresolved list if the name does not resolve.
  void InvokeBuiltin(Builtins::JavaScript id, InvokeJSFlags flags);

  // Store the code object for the given builtin in the target register and
  // setup the function in r1.
  void GetBuiltinEntry(Register target, Builtins::JavaScript id);

  Handle<Object> CodeObject() { return code_object_; }


  // ---------------------------------------------------------------------------
  // StatsCounter support

  void SetCounter(StatsCounter* counter, int value,
                  Register scratch1, Register scratch2);
  void IncrementCounter(StatsCounter* counter, int value,
                        Register scratch1, Register scratch2);
  void DecrementCounter(StatsCounter* counter, int value,
                        Register scratch1, Register scratch2);


  // ---------------------------------------------------------------------------
  // Debugging

  // Calls Abort(msg) if the condition cc is not satisfied.
  // Use --debug_code to enable.
  void Assert(Condition cc, const char* msg);
  void AssertRegisterIsRoot(Register reg, Heap::RootListIndex index);

  // Like Assert(), but always enabled.
  void Check(Condition cc, const char* msg);

  // Print a message to stdout and abort execution.
  void Abort(const char* msg);

  // Verify restrictions about code generated in stubs.
  void set_generating_stub(bool value) { generating_stub_ = value; }
  bool generating_stub() { return generating_stub_; }
  void set_allow_stub_calls(bool value) { allow_stub_calls_ = value; }
  bool allow_stub_calls() { return allow_stub_calls_; }

  // ---------------------------------------------------------------------------
  // Smi utilities

  // Jump if either of the registers contain a non-smi.
  void JumpIfNotBothSmi(Register reg1, Register reg2, Label* on_not_both_smi);
  // Jump if either of the registers contain a smi.
  void JumpIfEitherSmi(Register reg1, Register reg2, Label* on_either_smi);

  // ---------------------------------------------------------------------------
  // String utilities

  // Checks if both objects are sequential ASCII strings and jumps to label
  // if either is not. Assumes that neither object is a smi.
  void JumpIfNonSmisNotBothSequentialAsciiStrings(Register object1,
                                                  Register object2,
                                                  Register scratch1,
                                                  Register scratch2,
                                                  Label* failure);

  // Checks if both objects are sequential ASCII strings and jumps to label
  // if either is not.
  void JumpIfNotBothSequentialAsciiStrings(Register first,
                                           Register second,
                                           Register scratch1,
                                           Register scratch2,
                                           Label* not_flat_ascii_strings);

  // Checks if both instance types are sequential ASCII strings and jumps to
  // label if either is not.
  void JumpIfBothInstanceTypesAreNotSequentialAscii(
      Register first_object_instance_type,
      Register second_object_instance_type,
      Register scratch1,
      Register scratch2,
      Label* failure);

  // Check if instance type is sequential ASCII string and jump to label if
  // it is not.
  void JumpIfInstanceTypeIsNotSequentialAscii(Register type,
                                              Register scratch,
                                              Label* failure);


 private:
  void Jump(intptr_t target, RelocInfo::Mode rmode, Condition cond = al);
  void Call(intptr_t target, RelocInfo::Mode rmode, Condition cond = al);

  // Helper functions for generating invokes.
  void InvokePrologue(const ParameterCount& expected,
                      const ParameterCount& actual,
                      Handle<Code> code_constant,
                      Register code_reg,
                      Label* done,
                      InvokeFlag flag);

  // Activation support.
  void EnterFrame(StackFrame::Type type);
  void LeaveFrame(StackFrame::Type type);

  void InitializeNewString(Register string,
                           Register length,
                           Heap::RootListIndex map_index,
                           Register scratch1,
                           Register scratch2);

  bool generating_stub_;
  bool allow_stub_calls_;
  // This handle will be patched with the code object on installation.
  Handle<Object> code_object_;
};


#ifdef ENABLE_DEBUGGER_SUPPORT
// The code patcher is used to patch (typically) small parts of code e.g. for
// debugging and other types of instrumentation. When using the code patcher
// the exact number of bytes specified must be emitted. It is not legal to emit
// relocation information. If any of these constraints are violated it causes
// an assertion to fail.
class CodePatcher {
 public:
  CodePatcher(byte* address, int instructions);
  virtual ~CodePatcher();

  // Macro assembler to emit code.
  MacroAssembler* masm() { return &masm_; }

  // Emit an instruction directly.
  void Emit(Instr x);

  // Emit an address directly.
  void Emit(Address addr);

 private:
  byte* address_;  // The address of the code being patched.
  int instructions_;  // Number of instructions of the expected patch size.
  int size_;  // Number of bytes of the expected patch size.
  MacroAssembler masm_;  // Macro assembler used to generate the code.
};
#endif  // ENABLE_DEBUGGER_SUPPORT


// -----------------------------------------------------------------------------
// Static helper functions.

#ifdef GENERATED_CODE_COVERAGE
#define CODE_COVERAGE_STRINGIFY(x) #x
#define CODE_COVERAGE_TOSTRING(x) CODE_COVERAGE_STRINGIFY(x)
#define __FILE_LINE__ __FILE__ ":" CODE_COVERAGE_TOSTRING(__LINE__)
#define ACCESS_MASM(masm) masm->stop(__FILE_LINE__); masm->
#else
#define ACCESS_MASM(masm) masm->
#endif


} }  // namespace v8::internal

#endif  // V8_ARM_MACRO_ASSEMBLER_ARM_H_