Fix/unify root handling in code generation.

R=danno@chromium.org

Review URL: https://codereview.chromium.org/22670004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16132 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/macro-assembler-arm.cc

@@ -375,16 +375,13 @@ void MacroAssembler::LoadRoot(Register destination,
                               Heap::RootListIndex index,
                               Condition cond) {
   if (CpuFeatures::IsSupported(MOVW_MOVT_IMMEDIATE_LOADS) &&
-      !Heap::RootCanBeWrittenAfterInitialization(index) &&
+      isolate()->heap()->RootCanBeTreatedAsConstant(index) &&
       !predictable_code_size()) {
-    Handle<Object> root(isolate()->heap()->roots_array_start()[index],
-                        isolate());
-    if (!isolate()->heap()->InNewSpace(*root)) {
-      // The CPU supports fast immediate values, and this root will never
-      // change. We will load it as a relocatable immediate value.
-      mov(destination, Operand(root), LeaveCC, cond);
-      return;
-    }
+    // The CPU supports fast immediate values, and this root will never
+    // change. We will load it as a relocatable immediate value.
+    Handle<Object> root(&isolate()->heap()->roots_array_start()[index]);
+    mov(destination, Operand(root), LeaveCC, cond);
+    return;
   }
   ldr(destination, MemOperand(kRootRegister, index << kPointerSizeLog2), cond);
 }

src/heap.cc

@@ -3263,6 +3263,12 @@ bool Heap::RootCanBeWrittenAfterInitialization(Heap::RootListIndex root_index) {
 }
 
 
+bool Heap::RootCanBeTreatedAsConstant(RootListIndex root_index) {
+  return !RootCanBeWrittenAfterInitialization(root_index) &&
+      !InNewSpace(roots_array_start()[root_index]);
+}
+
+
 Object* RegExpResultsCache::Lookup(Heap* heap,
                                    String* key_string,
                                    Object* key_pattern,

src/heap.h

@@ -1615,6 +1615,8 @@ class Heap {
   // Generated code can embed direct references to non-writable roots if
   // they are in new space.
   static bool RootCanBeWrittenAfterInitialization(RootListIndex root_index);
+  // Generated code can treat direct references to this root as constant.
+  bool RootCanBeTreatedAsConstant(RootListIndex root_index);
 
   MUST_USE_RESULT MaybeObject* NumberToString(
       Object* number, bool check_number_string_cache = true,

src/ia32/code-stubs-ia32.cc

@@ -3956,11 +3956,7 @@ void NumberToStringStub::GenerateLookupNumberStringCache(MacroAssembler* masm,
   Register scratch = scratch2;
 
   // Load the number string cache.
-  ExternalReference roots_array_start =
-      ExternalReference::roots_array_start(masm->isolate());
-  __ mov(scratch, Immediate(Heap::kNumberStringCacheRootIndex));
-  __ mov(number_string_cache,
-         Operand::StaticArray(scratch, times_pointer_size, roots_array_start));
+  __ LoadRoot(number_string_cache, Heap::kNumberStringCacheRootIndex);
   // Make the hash mask from the length of the number string cache. It
   // contains two elements (number and string) for each cache entry.
   __ mov(mask, FieldOperand(number_string_cache, FixedArray::kLengthOffset));
@@ -5010,9 +5006,6 @@ void InstanceofStub::Generate(MacroAssembler* masm) {
   static const int8_t kCmpEdiOperandByte2 = BitCast<int8_t, uint8_t>(0x3d);
   static const int8_t kMovEaxImmediateByte = BitCast<int8_t, uint8_t>(0xb8);
 
-  ExternalReference roots_array_start =
-      ExternalReference::roots_array_start(masm->isolate());
-
   ASSERT_EQ(object.code(), InstanceofStub::left().code());
   ASSERT_EQ(function.code(), InstanceofStub::right().code());
 
@@ -5032,18 +5025,11 @@ void InstanceofStub::Generate(MacroAssembler* masm) {
   if (!HasCallSiteInlineCheck()) {
     // Look up the function and the map in the instanceof cache.
     Label miss;
-    __ mov(scratch, Immediate(Heap::kInstanceofCacheFunctionRootIndex));
-    __ cmp(function, Operand::StaticArray(scratch,
-                                          times_pointer_size,
-                                          roots_array_start));
+    __ CompareRoot(function, scratch, Heap::kInstanceofCacheFunctionRootIndex);
     __ j(not_equal, &miss, Label::kNear);
-    __ mov(scratch, Immediate(Heap::kInstanceofCacheMapRootIndex));
-    __ cmp(map, Operand::StaticArray(
-        scratch, times_pointer_size, roots_array_start));
+    __ CompareRoot(map, scratch, Heap::kInstanceofCacheMapRootIndex);
     __ j(not_equal, &miss, Label::kNear);
-    __ mov(scratch, Immediate(Heap::kInstanceofCacheAnswerRootIndex));
-    __ mov(eax, Operand::StaticArray(
-        scratch, times_pointer_size, roots_array_start));
+    __ LoadRoot(eax, Heap::kInstanceofCacheAnswerRootIndex);
     __ ret((HasArgsInRegisters() ? 0 : 2) * kPointerSize);
     __ bind(&miss);
   }
@@ -5058,12 +5044,8 @@ void InstanceofStub::Generate(MacroAssembler* masm) {
   // Update the global instanceof or call site inlined cache with the current
   // map and function. The cached answer will be set when it is known below.
   if (!HasCallSiteInlineCheck()) {
-  __ mov(scratch, Immediate(Heap::kInstanceofCacheMapRootIndex));
-  __ mov(Operand::StaticArray(scratch, times_pointer_size, roots_array_start),
-         map);
-  __ mov(scratch, Immediate(Heap::kInstanceofCacheFunctionRootIndex));
-  __ mov(Operand::StaticArray(scratch, times_pointer_size, roots_array_start),
-         function);
+    __ StoreRoot(map, scratch, Heap::kInstanceofCacheMapRootIndex);
+    __ StoreRoot(function, scratch, Heap::kInstanceofCacheFunctionRootIndex);
   } else {
     // The constants for the code patching are based on no push instructions
     // at the call site.
@@ -5097,10 +5079,8 @@ void InstanceofStub::Generate(MacroAssembler* masm) {
 
   __ bind(&is_instance);
   if (!HasCallSiteInlineCheck()) {
-    __ Set(eax, Immediate(0));
-    __ mov(scratch, Immediate(Heap::kInstanceofCacheAnswerRootIndex));
-    __ mov(Operand::StaticArray(scratch,
-                                times_pointer_size, roots_array_start), eax);
+    __ mov(eax, Immediate(0));
+    __ StoreRoot(eax, scratch, Heap::kInstanceofCacheAnswerRootIndex);
   } else {
     // Get return address and delta to inlined map check.
     __ mov(eax, factory->true_value());
@@ -5119,10 +5099,8 @@ void InstanceofStub::Generate(MacroAssembler* masm) {
 
   __ bind(&is_not_instance);
   if (!HasCallSiteInlineCheck()) {
-    __ Set(eax, Immediate(Smi::FromInt(1)));
-    __ mov(scratch, Immediate(Heap::kInstanceofCacheAnswerRootIndex));
-    __ mov(Operand::StaticArray(
-        scratch, times_pointer_size, roots_array_start), eax);
+    __ mov(eax, Immediate(Smi::FromInt(1)));
+    __ StoreRoot(eax, scratch, Heap::kInstanceofCacheAnswerRootIndex);
   } else {
     // Get return address and delta to inlined map check.
     __ mov(eax, factory->false_value());
@@ -5875,11 +5853,7 @@ void StringHelper::GenerateTwoCharacterStringTableProbe(MacroAssembler* masm,
 
   // Load the string table.
   Register string_table = c2;
-  ExternalReference roots_array_start =
-      ExternalReference::roots_array_start(masm->isolate());
-  __ mov(scratch, Immediate(Heap::kStringTableRootIndex));
-  __ mov(string_table,
-         Operand::StaticArray(scratch, times_pointer_size, roots_array_start));
+  __ LoadRoot(string_table, Heap::kStringTableRootIndex);
 
   // Calculate capacity mask from the string table capacity.
   Register mask = scratch2;
@@ -5967,12 +5941,7 @@ void StringHelper::GenerateHashInit(MacroAssembler* masm,
                                     Register scratch) {
   // hash = (seed + character) + ((seed + character) << 10);
   if (Serializer::enabled()) {
-    ExternalReference roots_array_start =
-        ExternalReference::roots_array_start(masm->isolate());
-    __ mov(scratch, Immediate(Heap::kHashSeedRootIndex));
-    __ mov(scratch, Operand::StaticArray(scratch,
-                                         times_pointer_size,
-                                         roots_array_start));
+    __ LoadRoot(scratch, Heap::kHashSeedRootIndex);
     __ SmiUntag(scratch);
     __ add(scratch, character);
     __ mov(hash, scratch);

src/ia32/macro-assembler-ia32.cc

@@ -54,6 +54,60 @@ MacroAssembler::MacroAssembler(Isolate* arg_isolate, void* buffer, int size)
 }
 
 
+void MacroAssembler::LoadRoot(Register destination, Heap::RootListIndex index) {
+  if (isolate()->heap()->RootCanBeTreatedAsConstant(index)) {
+    Handle<Object> value(&isolate()->heap()->roots_array_start()[index]);
+    mov(destination, value);
+    return;
+  }
+  ExternalReference roots_array_start =
+      ExternalReference::roots_array_start(isolate());
+  mov(destination, Immediate(index));
+  mov(destination, Operand::StaticArray(destination,
+                                        times_pointer_size,
+                                        roots_array_start));
+}
+
+
+void MacroAssembler::StoreRoot(Register source,
+                               Register scratch,
+                               Heap::RootListIndex index) {
+  ASSERT(Heap::RootCanBeWrittenAfterInitialization(index));
+  ExternalReference roots_array_start =
+      ExternalReference::roots_array_start(isolate());
+  mov(scratch, Immediate(index));
+  mov(Operand::StaticArray(scratch, times_pointer_size, roots_array_start),
+      source);
+}
+
+
+void MacroAssembler::CompareRoot(Register with,
+                                 Register scratch,
+                                 Heap::RootListIndex index) {
+  ExternalReference roots_array_start =
+      ExternalReference::roots_array_start(isolate());
+  mov(scratch, Immediate(index));
+  cmp(with, Operand::StaticArray(scratch,
+                                times_pointer_size,
+                                roots_array_start));
+}
+
+
+void MacroAssembler::CompareRoot(Register with, Heap::RootListIndex index) {
+  ASSERT(isolate()->heap()->RootCanBeTreatedAsConstant(index));
+  Handle<Object> value(&isolate()->heap()->roots_array_start()[index]);
+  cmp(with, value);
+}
+
+
+void MacroAssembler::CompareRoot(const Operand& with,
+                                 Heap::RootListIndex index) {
+  ASSERT(isolate()->heap()->RootCanBeTreatedAsConstant(index));
+  Handle<Object> value(&isolate()->heap()->roots_array_start()[index]);
+  cmp(with, value);
+}
+
+
 void MacroAssembler::InNewSpace(
     Register object,
     Register scratch,
@@ -432,21 +486,6 @@ void MacroAssembler::SafePush(const Immediate& x) {
 }
 
 
-void MacroAssembler::CompareRoot(Register with, Heap::RootListIndex index) {
-  // see ROOT_ACCESSOR macro in factory.h
-  Handle<Object> value(&isolate()->heap()->roots_array_start()[index]);
-  cmp(with, value);
-}
-
-
-void MacroAssembler::CompareRoot(const Operand& with,
-                                 Heap::RootListIndex index) {
-  // see ROOT_ACCESSOR macro in factory.h
-  Handle<Object> value(&isolate()->heap()->roots_array_start()[index]);
-  cmp(with, value);
-}
-
-
 void MacroAssembler::CmpObjectType(Register heap_object,
                                    InstanceType type,
                                    Register map) {

src/ia32/macro-assembler-ia32.h

@@ -61,6 +61,15 @@ class MacroAssembler: public Assembler {
   // macro assembler.
   MacroAssembler(Isolate* isolate, void* buffer, int size);
 
+  // Operations on roots in the root-array.
+  void LoadRoot(Register destination, Heap::RootListIndex index);
+  void StoreRoot(Register source, Register scratch, Heap::RootListIndex index);
+  void CompareRoot(Register with, Register scratch, Heap::RootListIndex index);
+  // These methods can only be used with constant roots (i.e. non-writable
+  // and not in new space).
+  void CompareRoot(Register with, Heap::RootListIndex index);
+  void CompareRoot(const Operand& with, Heap::RootListIndex index);
+
   // ---------------------------------------------------------------------------
   // GC Support
   enum RememberedSetFinalAction {
@@ -362,10 +371,6 @@ class MacroAssembler: public Assembler {
   void SafeSet(Register dst, const Immediate& x);
   void SafePush(const Immediate& x);
 
-  // Compare against a known root, e.g. undefined, null, true, ...
-  void CompareRoot(Register with, Heap::RootListIndex index);
-  void CompareRoot(const Operand& with, Heap::RootListIndex index);
-
   // Compare object type for heap object.
   // Incoming register is heap_object and outgoing register is map.
   void CmpObjectType(Register heap_object, InstanceType type, Register map);