[fullcodegen] Remove exception handling support.

src/full-codegen/full-codegen.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/full-codegen/full-codegen.h"
 
 #include "src/ast/ast-numbering.h"
 #include "src/ast/ast.h"
 #include "src/ast/prettyprinter.h"
 #include "src/ast/scopes.h"
@@ skipping 44 matching lines @@
       nesting_stack_(NULL),
       loop_depth_(0),
       operand_stack_depth_(0),
       globals_(NULL),
       context_(NULL),
       bailout_entries_(info->HasDeoptimizationSupport()
                            ? info->literal()->ast_node_count()
                            : 0,
                        info->zone()),
       back_edges_(2, info->zone()),
-      handler_table_(info->zone()),
       source_position_table_builder_(info->zone(),
                                      info->SourcePositionRecordingMode()),
       ic_total_count_(0) {
   DCHECK(!info->IsStub());
   Initialize(stack_limit);
 }
 
 // static
 CompilationJob* FullCodeGenerator::NewCompilationJob(CompilationInfo* info) {
   return new FullCodegenCompilationJob(info);
@@ skipping 32 matching lines @@
   if (cgen.HasStackOverflow()) {
     DCHECK(!isolate->has_pending_exception());
     return false;
   }
   unsigned table_offset = cgen.EmitBackEdgeTable();
 
   Handle<Code> code =
       CodeGenerator::MakeCodeEpilogue(&masm, nullptr, info, masm.CodeObject());
   cgen.PopulateDeoptimizationData(code);
   cgen.PopulateTypeFeedbackInfo(code);
-  cgen.PopulateHandlerTable(code);
   code->set_has_deoptimization_support(info->HasDeoptimizationSupport());
   code->set_has_reloc_info_for_serialization(info->will_serialize());
   code->set_allow_osr_at_loop_nesting_level(0);
   code->set_profiler_ticks(0);
   code->set_back_edge_table_offset(table_offset);
   Handle<ByteArray> source_positions =
       cgen.source_position_table_builder_.ToSourcePositionTable(
           isolate, Handle<AbstractCode>::cast(code));
   code->set_source_position_table(*source_positions);
   CodeGenerator::PrintCode(code, info);
@@ skipping 40 matching lines @@
 
 
 void FullCodeGenerator::PopulateTypeFeedbackInfo(Handle<Code> code) {
   Handle<TypeFeedbackInfo> info = isolate()->factory()->NewTypeFeedbackInfo();
   info->set_ic_total_count(ic_total_count_);
   DCHECK(!isolate()->heap()->InNewSpace(*info));
   code->set_type_feedback_info(*info);
 }
 
 
-void FullCodeGenerator::PopulateHandlerTable(Handle<Code> code) {
-  int handler_table_size = static_cast<int>(handler_table_.size());
-  Handle<HandlerTable> table =
-      Handle<HandlerTable>::cast(isolate()->factory()->NewFixedArray(
-          HandlerTable::LengthForRange(handler_table_size), TENURED));
-  for (int i = 0; i < handler_table_size; ++i) {
-    table->SetRangeStart(i, handler_table_[i].range_start);
-    table->SetRangeEnd(i, handler_table_[i].range_end);
-    table->SetRangeHandler(i, handler_table_[i].handler_offset,
-                           handler_table_[i].catch_prediction);
-    table->SetRangeData(i, handler_table_[i].stack_depth);
-  }
-  code->set_handler_table(*table);
-}
-
-
-int FullCodeGenerator::NewHandlerTableEntry() {
-  int index = static_cast<int>(handler_table_.size());
-  HandlerTableEntry entry = {0, 0, 0, 0, HandlerTable::UNCAUGHT};
-  handler_table_.push_back(entry);
-  return index;
-}
-
-
 bool FullCodeGenerator::MustCreateObjectLiteralWithRuntime(
     ObjectLiteral* expr) const {
   return masm()->serializer_enabled() ||
          !FastCloneShallowObjectStub::IsSupported(expr);
 }
 
 
 bool FullCodeGenerator::MustCreateArrayLiteralWithRuntime(
     ArrayLiteral* expr) const {
   return expr->depth() > 1 ||
@@ skipping 769 matching lines @@
     PrepareForBailoutForId(stmt->ElseId(), BailoutState::NO_REGISTERS);
   }
   __ bind(&done);
   PrepareForBailoutForId(stmt->IfId(), BailoutState::NO_REGISTERS);
 }
 
 void FullCodeGenerator::EmitContinue(Statement* target) {
   NestedStatement* current = nesting_stack_;
   int context_length = 0;
   // When continuing, we clobber the unpredictable value in the accumulator
-  // with one that's safe for GC.  If we hit an exit from the try block of
-  // try...finally on our way out, we will unconditionally preserve the
-  // accumulator on the stack.
+  // with one that's safe for GC.
   ClearAccumulator();
   while (!current->IsContinueTarget(target)) {
     if (HasStackOverflow()) return;
-    if (current->IsTryFinally()) {
-      Comment cmnt(masm(), "[ Deferred continue through finally");
-      current->Exit(&context_length);
-      DCHECK_EQ(-1, context_length);
-      current->AsTryFinally()->deferred_commands()->RecordContinue(target);
-      return;
-    }
     current = current->Exit(&context_length);
   }
   int stack_depth = current->GetStackDepthAtTarget();
   int stack_drop = operand_stack_depth_ - stack_depth;
   DCHECK_GE(stack_drop, 0);
   __ Drop(stack_drop);
   if (context_length > 0) {
     while (context_length > 0) {
       LoadContextField(context_register(), Context::PREVIOUS_INDEX);
       --context_length;
     }
     StoreToFrameField(StandardFrameConstants::kContextOffset,
                       context_register());
   }
 
   __ jmp(current->AsIteration()->continue_label());
 }
 
 void FullCodeGenerator::VisitContinueStatement(ContinueStatement* stmt) {
   Comment cmnt(masm_, "[ ContinueStatement");
   SetStatementPosition(stmt);
   EmitContinue(stmt->target());
 }
 
 void FullCodeGenerator::EmitBreak(Statement* target) {
   NestedStatement* current = nesting_stack_;
   int context_length = 0;
   // When breaking, we clobber the unpredictable value in the accumulator
-  // with one that's safe for GC.  If we hit an exit from the try block of
-  // try...finally on our way out, we will unconditionally preserve the
-  // accumulator on the stack.
+  // with one that's safe for GC.
   ClearAccumulator();
   while (!current->IsBreakTarget(target)) {
     if (HasStackOverflow()) return;
-    if (current->IsTryFinally()) {
-      Comment cmnt(masm(), "[ Deferred break through finally");
-      current->Exit(&context_length);
-      DCHECK_EQ(-1, context_length);
-      current->AsTryFinally()->deferred_commands()->RecordBreak(target);
-      return;
-    }
     current = current->Exit(&context_length);
   }
   int stack_depth = current->GetStackDepthAtTarget();
   int stack_drop = operand_stack_depth_ - stack_depth;
   DCHECK_GE(stack_drop, 0);
   __ Drop(stack_drop);
   if (context_length > 0) {
     while (context_length > 0) {
       LoadContextField(context_register(), Context::PREVIOUS_INDEX);
       --context_length;
     }
     StoreToFrameField(StandardFrameConstants::kContextOffset,
                       context_register());
   }
 
   __ jmp(current->AsBreakable()->break_label());
 }
 
 void FullCodeGenerator::VisitBreakStatement(BreakStatement* stmt) {
   Comment cmnt(masm_, "[ BreakStatement");
   SetStatementPosition(stmt);
   EmitBreak(stmt->target());
 }
 
 void FullCodeGenerator::EmitUnwindAndReturn() {
   NestedStatement* current = nesting_stack_;
   int context_length = 0;
   while (current != NULL) {
     if (HasStackOverflow()) return;
-    if (current->IsTryFinally()) {
-      Comment cmnt(masm(), "[ Deferred return through finally");
-      current->Exit(&context_length);
-      DCHECK_EQ(-1, context_length);
-      current->AsTryFinally()->deferred_commands()->RecordReturn();
-      return;
-    }
     current = current->Exit(&context_length);
   }
   EmitReturnSequence();
 }
 
 void FullCodeGenerator::EmitNewClosure(Handle<SharedFunctionInfo> info,
                                        bool pretenure) {
   // If we're running with the --always-opt or the --prepare-always-opt
   // flag, we need to use the runtime function so that the new function
   // we are creating here gets a chance to have its code optimized and
@@ skipping 261 matching lines @@
   decrement_loop_depth();
 }
 
 void FullCodeGenerator::VisitThisFunction(ThisFunction* expr) {
   LoadFromFrameField(JavaScriptFrameConstants::kFunctionOffset,
                      result_register());
   context()->Plug(result_register());
 }
 
 void FullCodeGenerator::VisitTryCatchStatement(TryCatchStatement* stmt) {
-  Comment cmnt(masm_, "[ TryCatchStatement");
-  SetStatementPosition(stmt, SKIP_BREAK);
-
-  // The try block adds a handler to the exception handler chain before
-  // entering, and removes it again when exiting normally.  If an exception
-  // is thrown during execution of the try block, the handler is consumed
-  // and control is passed to the catch block with the exception in the
-  // result register.
-
-  Label try_entry, handler_entry, exit;
-  __ jmp(&try_entry);
-  __ bind(&handler_entry);
-  if (stmt->clear_pending_message()) ClearPendingMessage();
-
-  // Exception handler code, the exception is in the result register.
-  // Extend the context before executing the catch block.
-  { Comment cmnt(masm_, "[ Extend catch context");
-    PushOperand(stmt->variable()->name());
-    PushOperand(result_register());
-    PushOperand(stmt->scope()->scope_info());
-    PushFunctionArgumentForContextAllocation();
-    CallRuntimeWithOperands(Runtime::kPushCatchContext);
-    StoreToFrameField(StandardFrameConstants::kContextOffset,
-                      context_register());
-  }
-
-  Scope* saved_scope = scope();
-  scope_ = stmt->scope();
-  DCHECK(scope_->declarations()->is_empty());
-  { WithOrCatch catch_body(this);
-    Visit(stmt->catch_block());
-  }
-  // Restore the context.
-  LoadContextField(context_register(), Context::PREVIOUS_INDEX);
-  StoreToFrameField(StandardFrameConstants::kContextOffset, context_register());
-  scope_ = saved_scope;
-  __ jmp(&exit);
-
-  // Try block code. Sets up the exception handler chain.
-  __ bind(&try_entry);
-
-  int handler_index = NewHandlerTableEntry();
-  EnterTryBlock(handler_index, &handler_entry, stmt->catch_prediction());
-  {
-    Comment cmnt_try(masm(), "[ Try block");
-    Visit(stmt->try_block());
-  }
-  ExitTryBlock(handler_index);
-  __ bind(&exit);
+  // Exception handling is not supported.
+  UNREACHABLE();
 }
 
 
 void FullCodeGenerator::VisitTryFinallyStatement(TryFinallyStatement* stmt) {
-  Comment cmnt(masm_, "[ TryFinallyStatement");
-  SetStatementPosition(stmt, SKIP_BREAK);
-
-  // Try finally is compiled by setting up a try-handler on the stack while
-  // executing the try body, and removing it again afterwards.
-  //
-  // The try-finally construct can enter the finally block in three ways:
-  // 1. By exiting the try-block normally. This exits the try block,
-  //    pushes the continuation token and falls through to the finally
-  //    block.
-  // 2. By exiting the try-block with a function-local control flow transfer
-  //    (break/continue/return). The site of the, e.g., break exits the
-  //    try block, pushes the continuation token and jumps to the
-  //    finally block. After the finally block executes, the execution
-  //    continues based on the continuation token to a block that
-  //    continues with the control flow transfer.
-  // 3. By exiting the try-block with a thrown exception. In the handler,
-  //    we push the exception and continuation token and jump to the
-  //    finally block (which will again dispatch based on the token once
-  //    it is finished).
-
-  Label try_entry, handler_entry, finally_entry;
-  DeferredCommands deferred(this, &finally_entry);
-
-  // Jump to try-handler setup and try-block code.
-  __ jmp(&try_entry);
-  __ bind(&handler_entry);
-
-  // Exception handler code.  This code is only executed when an exception
-  // is thrown.  Record the continuation and jump to the finally block.
-  {
-    Comment cmnt_handler(masm(), "[ Finally handler");
-    deferred.RecordThrow();
-  }
-
-  // Set up try handler.
-  __ bind(&try_entry);
-  int handler_index = NewHandlerTableEntry();
-  EnterTryBlock(handler_index, &handler_entry, stmt->catch_prediction());
-  {
-    Comment cmnt_try(masm(), "[ Try block");
-    TryFinally try_body(this, &deferred);
-    Visit(stmt->try_block());
-  }
-  ExitTryBlock(handler_index);
-  // Execute the finally block on the way out.  Clobber the unpredictable
-  // value in the result register with one that's safe for GC because the
-  // finally block will unconditionally preserve the result register on the
-  // stack.
-  ClearAccumulator();
-  deferred.EmitFallThrough();
-  // Fall through to the finally block.
-
-  // Finally block implementation.
-  __ bind(&finally_entry);
-  {
-    Comment cmnt_finally(masm(), "[ Finally block");
-    OperandStackDepthIncrement(2);  // Token and accumulator are on stack.
-    EnterFinallyBlock();
-    Visit(stmt->finally_block());
-    ExitFinallyBlock();
-    OperandStackDepthDecrement(2);  // Token and accumulator were on stack.
-  }
-
-  {
-    Comment cmnt_deferred(masm(), "[ Post-finally dispatch");
-    deferred.EmitCommands();  // Return to the calling code.
-  }
+  // Exception handling is not supported.
+  UNREACHABLE();
 }
 
 
 void FullCodeGenerator::VisitDebuggerStatement(DebuggerStatement* stmt) {
   Comment cmnt(masm_, "[ DebuggerStatement");
   SetStatementPosition(stmt);
 
   __ DebugBreak();
   // Ignore the return value.
 
@@ skipping 129 matching lines @@
   VisitForStackValue(expr->exception());
   SetExpressionPosition(expr);
   CallRuntimeWithOperands(Runtime::kThrow);
   // Never returns here.
 
   // Even though this expression doesn't produce a value, we need to simulate
   // plugging of the value context to ensure stack depth tracking is in sync.
   if (context()->IsStackValue()) OperandStackDepthIncrement(1);
 }
 
-void FullCodeGenerator::EnterTryBlock(
-    int handler_index, Label* handler,
-    HandlerTable::CatchPrediction catch_prediction) {
-  HandlerTableEntry* entry = &handler_table_[handler_index];
-  entry->range_start = masm()->pc_offset();
-  entry->handler_offset = handler->pos();
-  entry->stack_depth = operand_stack_depth_;
-  entry->catch_prediction = catch_prediction;
-
-  // We are using the operand stack depth, check for accuracy.
-  EmitOperandStackDepthCheck();
-
-  // Push context onto operand stack.
-  STATIC_ASSERT(TryBlockConstant::kElementCount == 1);
-  PushOperand(context_register());
-}
-
-
-void FullCodeGenerator::ExitTryBlock(int handler_index) {
-  HandlerTableEntry* entry = &handler_table_[handler_index];
-  entry->range_end = masm()->pc_offset();
-
-  // Drop context from operand stack.
-  DropOperands(TryBlockConstant::kElementCount);
-}
-
 
 void FullCodeGenerator::VisitCall(Call* expr) {
 #ifdef DEBUG
   // We want to verify that RecordJSReturnSite gets called on all paths
   // through this function.  Avoid early returns.
   expr->return_is_recorded_ = false;
 #endif
 
   Comment cmnt(masm_, (expr->tail_call_mode() == TailCallMode::kAllow)
                           ? "[ TailCall"
@@ skipping 100 matching lines @@
 
 void FullCodeGenerator::VisitEmptyParentheses(EmptyParentheses* expr) {
   UNREACHABLE();
 }
 
 
 void FullCodeGenerator::VisitRewritableExpression(RewritableExpression* expr) {
   Visit(expr->expression());
 }
 
-FullCodeGenerator::NestedStatement* FullCodeGenerator::TryFinally::Exit(
-    int* context_length) {
-  // The macros used here must preserve the result register.
-
-  // Calculate how many operands to drop to get down to handler block.
-  int stack_drop = codegen_->operand_stack_depth_ - GetStackDepthAtTarget();
-  DCHECK_GE(stack_drop, 0);
-
-  // Because the handler block contains the context of the finally
-  // code, we can restore it directly from there for the finally code
-  // rather than iteratively unwinding contexts via their previous
-  // links.
-  if (*context_length > 0) {
-    __ Drop(stack_drop);  // Down to the handler block.
-    // Restore the context to its dedicated register and the stack.
-    STATIC_ASSERT(TryBlockConstant::kElementCount == 1);
-    __ Pop(codegen_->context_register());
-    codegen_->StoreToFrameField(StandardFrameConstants::kContextOffset,
-                                codegen_->context_register());
-  } else {
-    // Down to the handler block and also drop context.
-    __ Drop(stack_drop + TryBlockConstant::kElementCount);
-  }
-
-  // The caller will ignore outputs.
-  *context_length = -1;
-  return previous_;
-}
-
-void FullCodeGenerator::DeferredCommands::RecordBreak(Statement* target) {
-  TokenId token = dispenser_.GetBreakContinueToken();
-  commands_.push_back({kBreak, token, target});
-  EmitJumpToFinally(token);
-}
-
-void FullCodeGenerator::DeferredCommands::RecordContinue(Statement* target) {
-  TokenId token = dispenser_.GetBreakContinueToken();
-  commands_.push_back({kContinue, token, target});
-  EmitJumpToFinally(token);
-}
-
-void FullCodeGenerator::DeferredCommands::RecordReturn() {
-  if (return_token_ == TokenDispenserForFinally::kInvalidToken) {
-    return_token_ = TokenDispenserForFinally::kReturnToken;
-    commands_.push_back({kReturn, return_token_, nullptr});
-  }
-  EmitJumpToFinally(return_token_);
-}
-
-void FullCodeGenerator::DeferredCommands::RecordThrow() {
-  if (throw_token_ == TokenDispenserForFinally::kInvalidToken) {
-    throw_token_ = TokenDispenserForFinally::kThrowToken;
-    commands_.push_back({kThrow, throw_token_, nullptr});
-  }
-  EmitJumpToFinally(throw_token_);
-}
-
-void FullCodeGenerator::DeferredCommands::EmitFallThrough() {
-  __ Push(Smi::FromInt(TokenDispenserForFinally::kFallThroughToken));
-  __ Push(result_register());
-}
-
-void FullCodeGenerator::DeferredCommands::EmitJumpToFinally(TokenId token) {
-  __ Push(Smi::FromInt(token));
-  __ Push(result_register());
-  __ jmp(finally_entry_);
-}
 
 bool FullCodeGenerator::TryLiteralCompare(CompareOperation* expr) {
   Expression* sub_expr;
   Handle<String> check;
   if (expr->IsLiteralCompareTypeof(&sub_expr, &check)) {
     SetExpressionPosition(expr);
     EmitLiteralCompareTypeof(expr, sub_expr, check);
     return true;
   }
 
@@ skipping 139 matching lines @@
   return info_->has_simple_parameters();
 }
 
 FunctionLiteral* FullCodeGenerator::literal() const { return info_->literal(); }
 
 #undef __
 
 
 }  // namespace internal
 }  // namespace v8