Allow Crankshaft to tolerate certain do-expressions

Crankshaft can't track operand/environment changes between arbitrary statements.
We need that to fully support do-expressions. Instead, a subset is supported
by bailing out on break statements, continue statements, and if we've made an
OSR entry within a do-expression.

This partial support is a good idea because do-expressions are a useful tool
for desugaring during parsing.

BUG=
R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/1769463002

Cr-Commit-Position: refs/heads/master@{#34491}

src/ast/ast-numbering.cc

@@ -138,7 +138,6 @@ void AstNumberingVisitor::VisitNativeFunctionLiteral(
 
 void AstNumberingVisitor::VisitDoExpression(DoExpression* node) {
   IncrementNodeCount();
-  DisableCrankshaft(kDoExpression);
   node->set_base_id(ReserveIdRange(DoExpression::num_ids()));
   Visit(node->block());
   Visit(node->result());

src/bailout-reason.h

@@ -56,7 +56,8 @@ namespace internal {
   V(kDestinationOfCopyNotAligned, "Destination of copy not aligned")           \
   V(kDontDeleteCellsCannotContainTheHole,                                      \
     "DontDelete cells can't contain the hole")                                 \
-  V(kDoExpression, "Do expression encountered")                                \
+  V(kDoExpressionUnmodelable,                                                  \
+    "Encountered a do-expression with unmodelable control statements")         \
   V(kDoPushArgumentNotImplementedForDoubleType,                                \
     "DoPushArgument not implemented for double type")                          \
   V(kEliminatedBoundsCheckFailed, "Eliminated bounds check failed")            \

src/crankshaft/hydrogen.cc

@@ -3569,9 +3569,16 @@ HBasicBlock* HOptimizedGraphBuilder::BuildLoopEntry() {
 
 HBasicBlock* HOptimizedGraphBuilder::BuildLoopEntry(
     IterationStatement* statement) {
-  HBasicBlock* loop_entry = osr()->HasOsrEntryAt(statement)
-      ? osr()->BuildOsrLoopEntry(statement)
-      : BuildLoopEntry();
+  HBasicBlock* loop_entry;
+
+  if (osr()->HasOsrEntryAt(statement)) {
+    loop_entry = osr()->BuildOsrLoopEntry(statement);
+    if (function_state()->IsInsideDoExpressionScope()) {
+      Bailout(kDoExpressionUnmodelable);
+    }
+  } else {
+    loop_entry = BuildLoopEntry();
+  }
   return loop_entry;
 }
 
@@ -4045,6 +4052,7 @@ FunctionState::FunctionState(HOptimizedGraphBuilder* owner,
       arguments_elements_(NULL),
       inlining_id_(inlining_id),
       outer_source_position_(SourcePosition::Unknown()),
+      do_expression_scope_count_(0),
       outer_(owner->function_state()) {
   if (outer_ != NULL) {
     // State for an inline function.
@@ -4829,6 +4837,11 @@ void HOptimizedGraphBuilder::VisitContinueStatement(
   DCHECK(!HasStackOverflow());
   DCHECK(current_block() != NULL);
   DCHECK(current_block()->HasPredecessor());
+
+  if (function_state()->IsInsideDoExpressionScope()) {
+    return Bailout(kDoExpressionUnmodelable);
+  }
+
   Scope* outer_scope = NULL;
   Scope* inner_scope = scope();
   int drop_extra = 0;
@@ -4861,6 +4874,11 @@ void HOptimizedGraphBuilder::VisitBreakStatement(BreakStatement* stmt) {
   DCHECK(!HasStackOverflow());
   DCHECK(current_block() != NULL);
   DCHECK(current_block()->HasPredecessor());
+
+  if (function_state()->IsInsideDoExpressionScope()) {
+    return Bailout(kDoExpressionUnmodelable);
+  }
+
   Scope* outer_scope = NULL;
   Scope* inner_scope = scope();
   int drop_extra = 0;
@@ -5520,10 +5538,12 @@ void HOptimizedGraphBuilder::VisitNativeFunctionLiteral(
 
 
 void HOptimizedGraphBuilder::VisitDoExpression(DoExpression* expr) {
+  DoExpressionScope scope(this);
   DCHECK(!HasStackOverflow());
   DCHECK(current_block() != NULL);
   DCHECK(current_block()->HasPredecessor());
-  return Bailout(kDoExpression);
+  CHECK_ALIVE(VisitBlock(expr->block()));
+  Visit(expr->result());
 }
 
 

src/crankshaft/hydrogen.h

@@ -888,6 +888,10 @@ class FunctionState final {
 
   int inlining_id() const { return inlining_id_; }
 
+  void IncrementInDoExpressionScope() { do_expression_scope_count_++; }
+  void DecrementInDoExpressionScope() { do_expression_scope_count_--; }
+  bool IsInsideDoExpressionScope() { return do_expression_scope_count_ > 0; }
+
  private:
   HOptimizedGraphBuilder* owner_;
 
@@ -924,6 +928,8 @@ class FunctionState final {
   int inlining_id_;
   SourcePosition outer_source_position_;
 
+  int do_expression_scope_count_;
+
   FunctionState* outer_;
 };
 
@@ -3038,6 +3044,19 @@ class NoObservableSideEffectsScope final {
   HGraphBuilder* builder_;
 };
 
+class DoExpressionScope final {
+ public:
+  explicit DoExpressionScope(HOptimizedGraphBuilder* builder)
+      : builder_(builder) {
+    builder_->function_state()->IncrementInDoExpressionScope();
+  }
+  ~DoExpressionScope() {
+    builder_->function_state()->DecrementInDoExpressionScope();
+  }
+
+ private:
+  HOptimizedGraphBuilder* builder_;
+};
 
 }  // namespace internal
 }  // namespace v8