Eliminate write barrier for global stores at compile time if value stored is a smi.

src/arm/lithium-codegen-arm.cc

 // Copyright 2011 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
@@ skipping 2233 matching lines @@
            FieldMemOperand(scratch, JSGlobalPropertyCell::kValueOffset));
     __ LoadRoot(ip, Heap::kTheHoleValueRootIndex);
     __ cmp(scratch2, ip);
     DeoptimizeIf(eq, instr->environment());
   }
 
   // Store the value.
   __ str(value, FieldMemOperand(scratch, JSGlobalPropertyCell::kValueOffset));
 
   // Cells are always in the remembered set.
-  __ RecordWriteField(scratch,
-                      JSGlobalPropertyCell::kValueOffset,
-                      value,
-                      scratch2,
-                      kLRHasBeenSaved,
-                      kSaveFPRegs,
-                      OMIT_REMEMBERED_SET);
+  if (instr->hydrogen()->NeedsWriteBarrier()) {
+    HType type = instr->hydrogen()->value()->type();
+    SmiCheck check_needed =
+        type.IsHeapObject() ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
+    __ RecordWriteField(scratch,
+                        JSGlobalPropertyCell::kValueOffset,
+                        value,
+                        scratch2,
+                        kLRHasBeenSaved,
+                        kSaveFPRegs,
+                        OMIT_REMEMBERED_SET,
+                        check_needed);
+  }
 }
 
 
 void LCodeGen::DoStoreGlobalGeneric(LStoreGlobalGeneric* instr) {
   ASSERT(ToRegister(instr->global_object()).is(r1));
   ASSERT(ToRegister(instr->value()).is(r0));
 
   __ mov(r2, Operand(instr->name()));
   Handle<Code> ic = instr->strict_mode()
       ? isolate()->builtins()->StoreIC_Initialize_Strict()
       : isolate()->builtins()->StoreIC_Initialize();
   CallCode(ic, RelocInfo::CODE_TARGET_CONTEXT, instr);
 }
 
 
 void LCodeGen::DoLoadContextSlot(LLoadContextSlot* instr) {
   Register context = ToRegister(instr->context());
   Register result = ToRegister(instr->result());
   __ ldr(result, ContextOperand(context, instr->slot_index()));
 }
 
 
 void LCodeGen::DoStoreContextSlot(LStoreContextSlot* instr) {
   Register context = ToRegister(instr->context());
   Register value = ToRegister(instr->value());
   MemOperand target = ContextOperand(context, instr->slot_index());
   __ str(value, target);
-  if (instr->needs_write_barrier()) {
+  if (instr->hydrogen()->NeedsWriteBarrier()) {
+    HType type = instr->hydrogen()->value()->type();
+    SmiCheck check_needed =
+        type.IsHeapObject() ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
     __ RecordWriteContextSlot(context,
                               target.offset(),
                               value,
                               scratch0(),
                               kLRHasBeenSaved,
-                              kSaveFPRegs);
+                              kSaveFPRegs,
+                              EMIT_REMEMBERED_SET,
+                              check_needed);
   }
 }
 
 
 void LCodeGen::DoLoadNamedField(LLoadNamedField* instr) {
   Register object = ToRegister(instr->InputAt(0));
   Register result = ToRegister(instr->result());
   if (instr->hydrogen()->is_in_object()) {
     __ ldr(result, FieldMemOperand(object, instr->hydrogen()->offset()));
   } else {
@@ skipping 985 matching lines @@
   int offset = instr->offset();
 
   ASSERT(!object.is(value));
 
   if (!instr->transition().is_null()) {
     __ mov(scratch, Operand(instr->transition()));
     __ str(scratch, FieldMemOperand(object, HeapObject::kMapOffset));
   }
 
   // Do the store.
+  HType type = instr->hydrogen()->value()->type();
+  SmiCheck check_needed =
+      type.IsHeapObject() ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
   if (instr->is_in_object()) {
     __ str(value, FieldMemOperand(object, offset));
-    if (instr->needs_write_barrier()) {
+    if (instr->hydrogen()->NeedsWriteBarrier()) {
       // Update the write barrier for the object for in-object properties.
-      __ RecordWriteField(
-          object, offset, value, scratch, kLRHasBeenSaved, kSaveFPRegs);
+      __ RecordWriteField(object,
+                          offset,
+                          value,
+                          scratch,
+                          kLRHasBeenSaved,
+                          kSaveFPRegs,
+                          EMIT_REMEMBERED_SET,
+                          check_needed);
     }
   } else {
     __ ldr(scratch, FieldMemOperand(object, JSObject::kPropertiesOffset));
     __ str(value, FieldMemOperand(scratch, offset));
-    if (instr->needs_write_barrier()) {
+    if (instr->hydrogen()->NeedsWriteBarrier()) {
       // Update the write barrier for the properties array.
       // object is used as a scratch register.
-      __ RecordWriteField(
-          scratch, offset, value, object, kLRHasBeenSaved, kSaveFPRegs);
+      __ RecordWriteField(scratch,
+                          offset,
+                          value,
+                          object,
+                          kLRHasBeenSaved,
+                          kSaveFPRegs,
+                          EMIT_REMEMBERED_SET,
+                          check_needed);
     }
   }
 }
 
 
 void LCodeGen::DoStoreNamedGeneric(LStoreNamedGeneric* instr) {
   ASSERT(ToRegister(instr->object()).is(r1));
   ASSERT(ToRegister(instr->value()).is(r0));
 
   // Name is always in r2.
@@ skipping 30 matching lines @@
     LConstantOperand* const_operand = LConstantOperand::cast(instr->key());
     int offset =
         ToInteger32(const_operand) * kPointerSize + FixedArray::kHeaderSize;
     __ str(value, FieldMemOperand(elements, offset));
   } else {
     __ add(scratch, elements, Operand(key, LSL, kPointerSizeLog2));
     __ str(value, FieldMemOperand(scratch, FixedArray::kHeaderSize));
   }
 
   if (instr->hydrogen()->NeedsWriteBarrier()) {
+    HType type = instr->hydrogen()->value()->type();
+    SmiCheck check_needed =
+        type.IsHeapObject() ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
     // Compute address of modified element and store it into key register.
     __ add(key, scratch, Operand(FixedArray::kHeaderSize - kHeapObjectTag));
-    __ RecordWrite(elements, key, value, kLRHasBeenSaved, kSaveFPRegs);
+    __ RecordWrite(elements,
+                   key,
+                   value,
+                   kLRHasBeenSaved,
+                   kSaveFPRegs,
+                   EMIT_REMEMBERED_SET,
+                   check_needed);
   }
 }
 
 
 void LCodeGen::DoStoreKeyedFastDoubleElement(
     LStoreKeyedFastDoubleElement* instr) {
   DwVfpRegister value = ToDoubleRegister(instr->value());
   Register elements = ToRegister(instr->elements());
   Register key = no_reg;
   Register scratch = scratch0();
@@ skipping 964 matching lines @@
   Register input = ToRegister(instr->InputAt(0));
   int true_block = chunk_->LookupDestination(instr->true_block_id());
   int false_block = chunk_->LookupDestination(instr->false_block_id());
   Label* true_label = chunk_->GetAssemblyLabel(true_block);
   Label* false_label = chunk_->GetAssemblyLabel(false_block);
 
   Condition final_branch_condition = EmitTypeofIs(true_label,
                                                   false_label,
                                                   input,
                                                   instr->type_literal());
-
-  EmitBranch(true_block, false_block, final_branch_condition);
+  if (final_branch_condition != kNoCondition) {
+    EmitBranch(true_block, false_block, final_branch_condition);
+  }
 }
 
 
 Condition LCodeGen::EmitTypeofIs(Label* true_label,
                                  Label* false_label,
                                  Register input,
                                  Handle<String> type_name) {
   Condition final_branch_condition = kNoCondition;
   Register scratch = scratch0();
   if (type_name->Equals(heap()->number_symbol())) {
@@ skipping 49 matching lines @@
                          FIRST_NONCALLABLE_SPEC_OBJECT_TYPE);
     __ b(lt, false_label);
     __ CompareInstanceType(input, scratch, LAST_NONCALLABLE_SPEC_OBJECT_TYPE);
     __ b(gt, false_label);
     // Check for undetectable objects => false.
     __ ldrb(ip, FieldMemOperand(input, Map::kBitFieldOffset));
     __ tst(ip, Operand(1 << Map::kIsUndetectable));
     final_branch_condition = eq;
 
   } else {
-    final_branch_condition = ne;
     __ b(false_label);
-    // A dead branch instruction will be generated after this point.
   }
 
   return final_branch_condition;
 }
 
 
 void LCodeGen::DoIsConstructCallAndBranch(LIsConstructCallAndBranch* instr) {
   Register temp1 = ToRegister(instr->TempAt(0));
   int true_block = chunk_->LookupDestination(instr->true_block_id());
   int false_block = chunk_->LookupDestination(instr->false_block_id());
@@ skipping 130 matching lines @@
   ASSERT(osr_pc_offset_ == -1);
   osr_pc_offset_ = masm()->pc_offset();
 }
 
 
 
 
 #undef __
 
 } }  // namespace v8::internal