debug.cc.svn-base

Google浏览器V8内核代码

// Copyright 2006-2008 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.
//     * Neither the name of Google Inc. nor the names of its
//       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.

#include "v8.h"

#include "api.h"
#include "arguments.h"
#include "bootstrapper.h"
#include "code-stubs.h"
#include "compiler.h"
#include "debug.h"
#include "execution.h"
#include "global-handles.h"
#include "natives.h"
#include "stub-cache.h"
#include "log.h"

namespace v8 { namespace internal {

static void PrintLn(v8::Local<v8::Value> value) {
  v8::Local<v8::String> s = value->ToString();
  char* data = NewArray<char>(s->Length() + 1);
  if (data == NULL) {
    V8::FatalProcessOutOfMemory("PrintLn");
    return;
  }
  s->WriteAscii(data);
  PrintF("%s\n", data);
  DeleteArray(data);
}


static Handle<Code> ComputeCallDebugBreak(int argc) {
  CALL_HEAP_FUNCTION(StubCache::ComputeCallDebugBreak(argc), Code);
}


static Handle<Code> ComputeCallDebugPrepareStepIn(int argc) {
  CALL_HEAP_FUNCTION(StubCache::ComputeCallDebugPrepareStepIn(argc), Code);
}


BreakLocationIterator::BreakLocationIterator(Handle<DebugInfo> debug_info,
                                             BreakLocatorType type) {
  debug_info_ = debug_info;
  type_ = type;
  reloc_iterator_ = NULL;
  reloc_iterator_original_ = NULL;
  Reset();  // Initialize the rest of the member variables.
}


BreakLocationIterator::~BreakLocationIterator() {
  ASSERT(reloc_iterator_ != NULL);
  ASSERT(reloc_iterator_original_ != NULL);
  delete reloc_iterator_;
  delete reloc_iterator_original_;
}


void BreakLocationIterator::Next() {
  AssertNoAllocation nogc;
  ASSERT(!RinfoDone());

  // Iterate through reloc info for code and original code stopping at each
  // breakable code target.
  bool first = break_point_ == -1;
  while (!RinfoDone()) {
    if (!first) RinfoNext();
    first = false;
    if (RinfoDone()) return;

    // Whenever a statement position or (plain) position is passed update the
    // current value of these.
    if (RelocInfo::IsPosition(rmode())) {
      if (RelocInfo::IsStatementPosition(rmode())) {
        statement_position_ =
            rinfo()->data() - debug_info_->shared()->start_position();
      }
      // Always update the position as we don't want that to be before the
      // statement position.
      position_ = rinfo()->data() - debug_info_->shared()->start_position();
      ASSERT(position_ >= 0);
      ASSERT(statement_position_ >= 0);
    }

    // Check for breakable code target. Look in the original code as setting
    // break points can cause the code targets in the running (debugged) code to
    // be of a different kind than in the original code.
    if (RelocInfo::IsCodeTarget(rmode())) {
      Address target = original_rinfo()->target_address();
      Code* code = Debug::GetCodeTarget(target);
      if (code->is_inline_cache_stub() || RelocInfo::IsConstructCall(rmode())) {
        break_point_++;
        return;
      }
      if (code->kind() == Code::STUB) {
        if (type_ == ALL_BREAK_LOCATIONS) {
          if (Debug::IsBreakStub(code)) {
            break_point_++;
            return;
          }
        } else {
          ASSERT(type_ == SOURCE_BREAK_LOCATIONS);
          if (Debug::IsSourceBreakStub(code)) {
            break_point_++;
            return;
          }
        }
      }
    }

    // Check for break at return.
    if (RelocInfo::IsJSReturn(rmode())) {
      // Set the positions to the end of the function.
      if (debug_info_->shared()->HasSourceCode()) {
        position_ = debug_info_->shared()->end_position() -
                    debug_info_->shared()->start_position();
      } else {
        position_ = 0;
      }
      statement_position_ = position_;
      break_point_++;
      return;
    }
  }
}


void BreakLocationIterator::Next(int count) {
  while (count > 0) {
    Next();
    count--;
  }
}


// Find the break point closest to the supplied address.
void BreakLocationIterator::FindBreakLocationFromAddress(Address pc) {
  // Run through all break points to locate the one closest to the address.
  int closest_break_point = 0;
  int distance = kMaxInt;
  while (!Done()) {
    // Check if this break point is closer that what was previously found.
    if (this->pc() < pc && pc - this->pc() < distance) {
      closest_break_point = break_point();
      distance = pc - this->pc();
      // Check whether we can't get any closer.
      if (distance == 0) break;
    }
    Next();
  }

  // Move to the break point found.
  Reset();
  Next(closest_break_point);
}


// Find the break point closest to the supplied source position.
void BreakLocationIterator::FindBreakLocationFromPosition(int position) {
  // Run through all break points to locate the one closest to the source
  // position.
  int closest_break_point = 0;
  int distance = kMaxInt;
  while (!Done()) {
    // Check if this break point is closer that what was previously found.
    if (position <= statement_position() &&
        statement_position() - position < distance) {
      closest_break_point = break_point();
      distance = statement_position() - position;
      // Check whether we can't get any closer.
      if (distance == 0) break;
    }
    Next();
  }

  // Move to the break point found.
  Reset();
  Next(closest_break_point);
}


void BreakLocationIterator::Reset() {
  // Create relocation iterators for the two code objects.
  if (reloc_iterator_ != NULL) delete reloc_iterator_;
  if (reloc_iterator_original_ != NULL) delete reloc_iterator_original_;
  reloc_iterator_ = new RelocIterator(debug_info_->code());
  reloc_iterator_original_ = new RelocIterator(debug_info_->original_code());

  // Position at the first break point.
  break_point_ = -1;
  position_ = 1;
  statement_position_ = 1;
  Next();
}


bool BreakLocationIterator::Done() const {
  return RinfoDone();
}


void BreakLocationIterator::SetBreakPoint(Handle<Object> break_point_object) {
  // If there is not already a real break point here patch code with debug
  // break.
  if (!HasBreakPoint()) {
    SetDebugBreak();
  }
  ASSERT(IsDebugBreak());
  // Set the break point information.
  DebugInfo::SetBreakPoint(debug_info_, code_position(),
                           position(), statement_position(),
                           break_point_object);
}


void BreakLocationIterator::ClearBreakPoint(Handle<Object> break_point_object) {
  // Clear the break point information.
  DebugInfo::ClearBreakPoint(debug_info_, code_position(), break_point_object);
  // If there are no more break points here remove the debug break.
  if (!HasBreakPoint()) {
    ClearDebugBreak();
    ASSERT(!IsDebugBreak());
  }
}


void BreakLocationIterator::SetOneShot() {
  // If there is a real break point here no more to do.
  if (HasBreakPoint()) {
    ASSERT(IsDebugBreak());
    return;
  }

  // Patch code with debug break.
  SetDebugBreak();
}


void BreakLocationIterator::ClearOneShot() {
  // If there is a real break point here no more to do.
  if (HasBreakPoint()) {
    ASSERT(IsDebugBreak());
    return;
  }

  // Patch code removing debug break.
  ClearDebugBreak();
  ASSERT(!IsDebugBreak());
}


void BreakLocationIterator::SetDebugBreak() {
  // If there is already a break point here just return. This might happen if
  // the same code is flooded with break points twice. Flooding the same
  // function twice might happen when stepping in a function with an exception
  // handler as the handler and the function is the same.
  if (IsDebugBreak()) {
    return;
  }

  if (RelocInfo::IsJSReturn(rmode())) {
    // This path is currently only used on IA32 as JSExitFrame on ARM uses a
    // stub.
    // Patch the JS frame exit code with a debug break call. See
    // VisitReturnStatement and ExitJSFrame in codegen-ia32.cc for the
    // precise return instructions sequence.
    ASSERT(Debug::kIa32JSReturnSequenceLength >=
           Debug::kIa32CallInstructionLength);
    rinfo()->patch_code_with_call(Debug::debug_break_return_entry()->entry(),
        Debug::kIa32JSReturnSequenceLength - Debug::kIa32CallInstructionLength);
  } else {
    // Patch the original code with the current address as the current address
    // might have changed by the inline caching since the code was copied.
    original_rinfo()->set_target_address(rinfo()->target_address());

    // Patch the code to invoke the builtin debug break function matching the
    // calling convention used by the call site.
    Handle<Code> dbgbrk_code(Debug::FindDebugBreak(rinfo()));
    rinfo()->set_target_address(dbgbrk_code->entry());
  }
  ASSERT(IsDebugBreak());
}


void BreakLocationIterator::ClearDebugBreak() {
  if (RelocInfo::IsJSReturn(rmode())) {
    // Restore the JS frame exit code.
    rinfo()->patch_code(original_rinfo()->pc(),
                        Debug::kIa32JSReturnSequenceLength);
  } else {
    // Patch the code to the original invoke.
    rinfo()->set_target_address(original_rinfo()->target_address());
  }
  ASSERT(!IsDebugBreak());
}


void BreakLocationIterator::PrepareStepIn() {
  // Step in can only be prepared if currently positioned on an IC call or
  // construct call.
  Address target = rinfo()->target_address();
  Code* code = Debug::GetCodeTarget(target);
  if (code->is_call_stub()) {
    // Step in through IC call is handled by the runtime system. Therefore make
    // sure that the any current IC is cleared and the runtime system is
    // called. If the executing code has a debug break at the location change
    // the call in the original code as it is the code there that will be
    // executed in place of the debug break call.
    Handle<Code> stub = ComputeCallDebugPrepareStepIn(code->arguments_count());
    if (IsDebugBreak()) {
      original_rinfo()->set_target_address(stub->entry());
    } else {
      rinfo()->set_target_address(stub->entry());
    }
  } else {
    // Step in through constructs call requires no changes to the running code.
    ASSERT(RelocInfo::IsConstructCall(rmode()));
  }
}


// Check whether the break point is at a position which will exit the function.
bool BreakLocationIterator::IsExit() const {
  return (RelocInfo::IsJSReturn(rmode()));
}


bool BreakLocationIterator::HasBreakPoint() {
  return debug_info_->HasBreakPoint(code_position());
}


// Check whether there is a debug break at the current position.
bool BreakLocationIterator::IsDebugBreak() {
  if (RelocInfo::IsJSReturn(rmode())) {
    // This is IA32 specific but works as long as the ARM version
    // still uses a stub for JSExitFrame.
    //
    // TODO(1240753): Make the test architecture independent or split
    // parts of the debugger into architecture dependent files.
    return (*(rinfo()->pc()) == 0xE8);
  } else {
    return Debug::IsDebugBreak(rinfo()->target_address());
  }
}


Object* BreakLocationIterator::BreakPointObjects() {
  return debug_info_->GetBreakPointObjects(code_position());
}


bool BreakLocationIterator::RinfoDone() const {
  ASSERT(reloc_iterator_->done() == reloc_iterator_original_->done());
  return reloc_iterator_->done();
}


void BreakLocationIterator::RinfoNext() {
  reloc_iterator_->next();
  reloc_iterator_original_->next();
#ifdef DEBUG
  ASSERT(reloc_iterator_->done() == reloc_iterator_original_->done());
  if (!reloc_iterator_->done()) {
    ASSERT(rmode() == original_rmode());