Support fast case for-in in Crankshaft.

src/arm/full-codegen-arm.cc

Index: src/arm/full-codegen-arm.cc
diff --git a/src/arm/full-codegen-arm.cc b/src/arm/full-codegen-arm.cc
index eba4976502629e5f794e3866743dfdebcfbd7f90..ebee952c86973740da40cf5d3d458d219498bd93 100644
--- a/src/arm/full-codegen-arm.cc
+++ b/src/arm/full-codegen-arm.cc
@@ -934,6 +934,8 @@ void FullCodeGenerator::VisitForInStatement(ForInStatement* stmt) {
   __ cmp(r0, null_value);
   __ b(eq, &exit);
 
+  PrepareForBailoutForId(stmt->PrepareId(), TOS_REG);
+
   // Convert the object to a JS object.
   Label convert, done_convert;
   __ JumpIfSmi(r0, &convert);
@@ -955,48 +957,7 @@ void FullCodeGenerator::VisitForInStatement(ForInStatement* stmt) {
   // the JSObject::IsSimpleEnum cache validity checks. If we cannot
   // guarantee cache validity, call the runtime system to check cache
   // validity or get the property names in a fixed array.
-  Label next;
-  // Preload a couple of values used in the loop.
-  Register  empty_fixed_array_value = r6;
-  __ LoadRoot(empty_fixed_array_value, Heap::kEmptyFixedArrayRootIndex);
-  Register empty_descriptor_array_value = r7;
-  __ LoadRoot(empty_descriptor_array_value,
-              Heap::kEmptyDescriptorArrayRootIndex);
-  __ mov(r1, r0);
-  __ bind(&next);
-
-  // Check that there are no elements.  Register r1 contains the
-  // current JS object we've reached through the prototype chain.
-  __ ldr(r2, FieldMemOperand(r1, JSObject::kElementsOffset));
-  __ cmp(r2, empty_fixed_array_value);
-  __ b(ne, &call_runtime);
-
-  // Check that instance descriptors are not empty so that we can
-  // check for an enum cache.  Leave the map in r2 for the subsequent
-  // prototype load.
-  __ ldr(r2, FieldMemOperand(r1, HeapObject::kMapOffset));
-  __ ldr(r3, FieldMemOperand(r2, Map::kInstanceDescriptorsOrBitField3Offset));
-  __ JumpIfSmi(r3, &call_runtime);
-
-  // Check that there is an enum cache in the non-empty instance
-  // descriptors (r3).  This is the case if the next enumeration
-  // index field does not contain a smi.
-  __ ldr(r3, FieldMemOperand(r3, DescriptorArray::kEnumerationIndexOffset));
-  __ JumpIfSmi(r3, &call_runtime);
-
-  // For all objects but the receiver, check that the cache is empty.
-  Label check_prototype;
-  __ cmp(r1, r0);
-  __ b(eq, &check_prototype);
-  __ ldr(r3, FieldMemOperand(r3, DescriptorArray::kEnumCacheBridgeCacheOffset));
-  __ cmp(r3, empty_fixed_array_value);
-  __ b(ne, &call_runtime);
-
-  // Load the prototype from the map and loop if non-null.
-  __ bind(&check_prototype);
-  __ ldr(r1, FieldMemOperand(r2, Map::kPrototypeOffset));
-  __ cmp(r1, null_value);
-  __ b(ne, &next);
+  __ CheckEnumCache(null_value, &call_runtime);
 
   // The enum cache is valid.  Load the map of the object being
   // iterated over and use the cache for the iteration.
@@ -1049,6 +1010,7 @@ void FullCodeGenerator::VisitForInStatement(ForInStatement* stmt) {
   __ Push(r1, r0);  // Fixed array length (as smi) and initial index.
 
   // Generate code for doing the condition check.
+  PrepareForBailoutForId(stmt->BodyId(), NO_REGISTERS);
   __ bind(&loop);
   // Load the current count to r0, load the length to r1.
   __ Ldrd(r0, r1, MemOperand(sp, 0 * kPointerSize));
@@ -1092,7 +1054,7 @@ void FullCodeGenerator::VisitForInStatement(ForInStatement* stmt) {
   __ mov(result_register(), r3);
   // Perform the assignment as if via '='.
   { EffectContext context(this);
-    EmitAssignment(stmt->each(), stmt->AssignmentId());
+    EmitAssignment(stmt->each());
   }
 
   // Generate code for the body of the loop.
@@ -1113,6 +1075,7 @@ void FullCodeGenerator::VisitForInStatement(ForInStatement* stmt) {
   __ Drop(5);
 
   // Exit and decrement the loop depth.
+  PrepareForBailoutForId(stmt->ExitId(), NO_REGISTERS);
   __ bind(&exit);
   decrement_loop_depth();
 }
@@ -1874,7 +1837,7 @@ void FullCodeGenerator::EmitBinaryOp(BinaryOperation* expr,
 }
 
 
-void FullCodeGenerator::EmitAssignment(Expression* expr, int bailout_ast_id) {
+void FullCodeGenerator::EmitAssignment(Expression* expr) {
   // Invalid left-hand sides are rewritten to have a 'throw
   // ReferenceError' on the left-hand side.
   if (!expr->IsValidLeftHandSide()) {
@@ -1926,7 +1889,6 @@ void FullCodeGenerator::EmitAssignment(Expression* expr, int bailout_ast_id) {
       break;
     }
   }
-  PrepareForBailoutForId(bailout_ast_id, TOS_REG);
   context()->Plug(r0);
 }