Debugger: use debug break slots instead of ICs (except for calls).

src/debug.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/api.h"
 #include "src/arguments.h"
 #include "src/bootstrapper.h"
 #include "src/code-stubs.h"
@@ skipping 66 matching lines @@
                                   BreakLocatorType type)
     : debug_info_(debug_info),
       type_(type),
       reloc_iterator_(debug_info->code(),
                       ~RelocInfo::ModeMask(RelocInfo::CODE_AGE_SEQUENCE)),
       reloc_iterator_original_(
           debug_info->original_code(),
           ~RelocInfo::ModeMask(RelocInfo::CODE_AGE_SEQUENCE)),
       break_index_(-1),
       position_(1),
-      statement_position_(1),
-      has_immediate_position_(false) {
+      statement_position_(1) {
   Next();
 }
 
 
 void BreakLocation::Iterator::Next() {
   DisallowHeapAllocation no_gc;
   DCHECK(!RinfoDone());
 
   // Iterate through reloc info for code and original code stopping at each
   // breakable code target.
   bool first = break_index_ == -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_ = static_cast<int>(
             rinfo()->data() - debug_info_->shared()->start_position());
       }
       // Always update the position as we don't want that to be before the
       // statement position.
       position_ = static_cast<int>(rinfo()->data() -
                                    debug_info_->shared()->start_position());
       DCHECK(position_ >= 0);
       DCHECK(statement_position_ >= 0);
-      has_immediate_position_ = true;
       continue;
     }
 
     // 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() - 1;
       } else {
         position_ = 0;
       }
       statement_position_ = position_;
       break_index_++;
       break;
     }
 
     if (RelocInfo::IsCodeTarget(rmode())) {
       // 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.
       Address target = original_rinfo()->target_address();
       Code* code = Code::GetCodeFromTargetAddress(target);
 
       if (RelocInfo::IsConstructCall(rmode()) || code->is_call_stub()) {
         break_index_++;
         break;
       }
 
-      // Skip below if we only want locations for calls and returns.
-      if (type_ == CALLS_AND_RETURNS) continue;
-
-      // Only break at an inline cache if it has an immediate position attached.
-      if (has_immediate_position_ &&
-          (code->is_inline_cache_stub() && !code->is_binary_op_stub() &&
-           !code->is_compare_ic_stub() && !code->is_to_boolean_ic_stub())) {
+      if (code->kind() == Code::STUB &&
+          CodeStub::GetMajorKey(code) == CodeStub::CallFunction) {
         break_index_++;
         break;
       }
-      if (code->kind() == Code::STUB) {
-        if (RelocInfo::IsDebuggerStatement(rmode())) {
-          break_index_++;
-          break;
-        } else if (CodeStub::GetMajorKey(code) == CodeStub::CallFunction) {
-          break_index_++;
-          break;
-        }
-      }
+    }
+
+    // Skip below if we only want locations for calls and returns.
+    if (type_ == CALLS_AND_RETURNS) continue;
+
+    if (RelocInfo::IsDebuggerStatement(rmode())) {
+      break_index_++;
+      break;
     }
 
     if (RelocInfo::IsDebugBreakSlot(rmode()) && type_ != CALLS_AND_RETURNS) {
       // There is always a possible break point at a debug break slot.
       break_index_++;
       break;
     }
   }
-  has_immediate_position_ = false;
 }
 
 
 // Find the break point at the supplied address, or the closest one before
 // the address.
 BreakLocation BreakLocation::FromAddress(Handle<DebugInfo> debug_info,
                                          BreakLocatorType type, Address pc) {
   Iterator it(debug_info, type);
   it.SkipTo(BreakIndexFromAddress(debug_info, type, pc));
   return it.GetBreakLocation();
@@ skipping 192 matching lines @@
 }
 
 
 // Find the builtin to use for invoking the debug break
 static Handle<Code> DebugBreakForIC(Handle<Code> code, RelocInfo::Mode mode) {
   Isolate* isolate = code->GetIsolate();
 
   // Find the builtin debug break function matching the calling convention
   // used by the call site.
   if (code->is_inline_cache_stub()) {
-    switch (code->kind()) {
-      case Code::CALL_IC:
-        return isolate->builtins()->CallICStub_DebugBreak();
-
-      case Code::LOAD_IC:
-        return isolate->builtins()->LoadIC_DebugBreak();
-
-      case Code::STORE_IC:
-        return isolate->builtins()->StoreIC_DebugBreak();
-
-      case Code::KEYED_LOAD_IC:
-        return isolate->builtins()->KeyedLoadIC_DebugBreak();
-
-      case Code::KEYED_STORE_IC:
-        return isolate->builtins()->KeyedStoreIC_DebugBreak();
-
-      case Code::COMPARE_NIL_IC:
-        return isolate->builtins()->CompareNilIC_DebugBreak();
-
-      default:
-        UNREACHABLE();
-    }
+    DCHECK(code->kind() == Code::CALL_IC);
+    return isolate->builtins()->CallICStub_DebugBreak();
   }
   if (RelocInfo::IsConstructCall(mode)) {
     if (code->has_function_cache()) {
       return isolate->builtins()->CallConstructStub_Recording_DebugBreak();
     } else {
       return isolate->builtins()->CallConstructStub_DebugBreak();
     }
   }
   if (code->kind() == Code::STUB) {
     DCHECK(CodeStub::GetMajorKey(*code) == CodeStub::CallFunction);
@@ skipping 831 matching lines @@
   // Get the debug info (create it if it does not exist).
   Handle<JSFunction> function(summary.function());
   Handle<SharedFunctionInfo> shared(function->shared());
   if (!EnsureDebugInfo(shared, function)) {
     // Return if ensuring debug info failed.
     return;
   }
   Handle<DebugInfo> debug_info = GetDebugInfo(shared);
 
   // Compute whether or not the target is a call target.
-  bool is_load_or_store = false;
-  bool is_inline_cache_stub = false;
   bool is_at_restarted_function = false;
   Handle<Code> call_function_stub;
 
   // PC points to the instruction after the current one, possibly a break
   // location as well. So the "- 1" to exclude it from the search.
   Address call_pc = summary.pc() - 1;
   BreakLocation location =
       BreakLocation::FromAddress(debug_info, ALL_BREAK_LOCATIONS, call_pc);
 
   if (thread_local_.restarter_frame_function_pointer_ == NULL) {
     if (location.IsCodeTarget()) {
       Handle<Code> target_code = location.CodeTarget();
-      is_inline_cache_stub = target_code->is_inline_cache_stub();
-      is_load_or_store = is_inline_cache_stub && !target_code->is_call_stub();
 
       // Check if target code is CallFunction stub.
       Handle<Code> maybe_call_function_stub = target_code;
       // If there is a breakpoint at this line look at the original code to
       // check if it is a CallFunction stub.
       if (location.IsDebugBreak()) {
         maybe_call_function_stub = location.OriginalCodeTarget();
       }
       if ((maybe_call_function_stub->kind() == Code::STUB &&
            CodeStub::GetMajorKey(*maybe_call_function_stub) ==
@@ skipping 26 matching lines @@
     }
     // Step out: If there is a JavaScript caller frame, we need to
     // flood it with breakpoints.
     if (!frames_it.done()) {
       // Fill the function to return to with one-shot break points.
       JSFunction* function = frames_it.frame()->function();
       FloodWithOneShot(Handle<JSFunction>(function));
       // Set target frame pointer.
       ActivateStepOut(frames_it.frame());
     }
-  } else if (!(is_inline_cache_stub || location.IsConstructCall() ||
-               !call_function_stub.is_null() || is_at_restarted_function) ||
-             step_action == StepNext || step_action == StepMin) {
-    // Step next or step min.
+    return;
+  }
 
-    // Fill the current function with one-shot break points.
-    // If we are stepping into another frame, only fill calls and returns.
-    FloodWithOneShot(function, step_action == StepFrame ? CALLS_AND_RETURNS
-                                                        : ALL_BREAK_LOCATIONS);
-
-    // Remember source position and frame to handle step next.
-    thread_local_.last_statement_position_ =
-        debug_info->code()->SourceStatementPosition(summary.pc());
-    thread_local_.last_fp_ = frame->UnpaddedFP();
-  } else {
+  if (step_action != StepNext && step_action != StepMin) {
     // If there's restarter frame on top of the stack, just get the pointer
     // to function which is going to be restarted.
     if (is_at_restarted_function) {
       Handle<JSFunction> restarted_function(
           JSFunction::cast(*thread_local_.restarter_frame_function_pointer_));
       FloodWithOneShot(restarted_function);
     } else if (!call_function_stub.is_null()) {
       // If it's CallFunction stub ensure target function is compiled and flood
       // it with one shot breakpoints.
       bool is_call_ic = call_function_stub->kind() == Code::CALL_IC;
@@ skipping 40 matching lines @@
           i -= 1;
         }
       }
 
       if (fun->IsJSFunction()) {
         Handle<JSFunction> js_function(JSFunction::cast(fun));
         FloodWithOneShotGeneric(js_function);
       }
     }
 
-    // Fill the current function with one-shot break points even for step in on
-    // a call target as the function called might be a native function for
-    // which step in will not stop. It also prepares for stepping in
-    // getters/setters.
-    // If we are stepping into another frame, only fill calls and returns.
-    FloodWithOneShot(function, step_action == StepFrame ? CALLS_AND_RETURNS
-                                                        : ALL_BREAK_LOCATIONS);
-
-    if (is_load_or_store) {
-      // Remember source position and frame to handle step in getter/setter. If
-      // there is a custom getter/setter it will be handled in
-      // Object::Get/SetPropertyWithAccessor, otherwise the step action will be
-      // propagated on the next Debug::Break.
-      thread_local_.last_statement_position_ =
-          debug_info->code()->SourceStatementPosition(summary.pc());
-      thread_local_.last_fp_ = frame->UnpaddedFP();
-    }
-
-    // Step in or Step in min
-    // Step in through construct call requires no changes to the running code.
-    // Step in through getters/setters should already be prepared as well
-    // because caller of this function (Debug::PrepareStep) is expected to
-    // flood the top frame's function with one shot breakpoints.
-    // Step in through CallFunction stub should also be prepared by caller of
-    // this function (Debug::PrepareStep) which should flood target function
-    // with breakpoints.
-    DCHECK(location.IsConstructCall() || is_inline_cache_stub ||
-           !call_function_stub.is_null() || is_at_restarted_function);
     ActivateStepIn(frame);
   }
+
+  // Fill the current function with one-shot break points even for step in on
+  // a call target as the function called might be a native function for
+  // which step in will not stop. It also prepares for stepping in
+  // getters/setters.
+  // If we are stepping into another frame, only fill calls and returns.
+  FloodWithOneShot(function, step_action == StepFrame ? CALLS_AND_RETURNS
+                                                      : ALL_BREAK_LOCATIONS);
+
+  // Remember source position and frame to handle step next.
+  thread_local_.last_statement_position_ =
+      debug_info->code()->SourceStatementPosition(summary.pc());
+  thread_local_.last_fp_ = frame->UnpaddedFP();
 }
 
 
 // Check whether the current debug break should be reported to the debugger. It
 // is used to have step next and step in only report break back to the debugger
 // if on a different frame or in a different statement. In some situations
 // there will be several break points in the same statement when the code is
 // flooded with one-shot break points. This function helps to perform several
 // steps before reporting break back to the debugger.
 bool Debug::StepNextContinue(BreakLocation* break_location,
@@ skipping 1950 matching lines @@
 }
 
 
 void LockingCommandMessageQueue::Clear() {
   base::LockGuard<base::Mutex> lock_guard(&mutex_);
   queue_.Clear();
 }
 
 }  // namespace internal
 }  // namespace v8