Array index computation dehoisting.

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index 9d262fc811724c985c6ddc96697c218e6daab976..7d737961ffb3330dea11153f147627b56521ebd4 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -3954,7 +3954,7 @@ class HLoadKeyedFastElement: public HTemplateInstruction<2> {
   HLoadKeyedFastElement(HValue* obj,
                         HValue* key,
                         HoleCheckMode hole_check_mode = PERFORM_HOLE_CHECK)
-      : hole_check_mode_(hole_check_mode) {
+      : hole_check_mode_(hole_check_mode), index_offset_(0) {
     SetOperandAt(0, obj);
     SetOperandAt(1, key);
     set_representation(Representation::Tagged());
@@ -3964,6 +3964,8 @@ class HLoadKeyedFastElement: public HTemplateInstruction<2> {
 
   HValue* object() { return OperandAt(0); }
   HValue* key() { return OperandAt(1); }
+  uint32_t index_offset() { return index_offset_; }
+  void SetIndexOffset(uint32_t index_offset) { index_offset_ = index_offset; }
 
   virtual Representation RequiredInputRepresentation(int index) {
     // The key is supposed to be Integer32.
@@ -3987,12 +3989,14 @@ class HLoadKeyedFastElement: public HTemplateInstruction<2> {
 
  private:
   HoleCheckMode hole_check_mode_;
+  uint32_t index_offset_;

[Jakob Kummerow, 2012/05/08 13:46:26]

Why is this a uint32_t? In hydrogen.cc, you're passing in an int32_t that indeed
can be negative. Please use consistently signed variable types. (Same below.)

[Massi, 2012/05/14 13:48:52]

This is unsigned because on ia32 and x64 we can only put positive displacements
in the machine code (I mean, embedded in the array element access instruction).
Making this signed would generate more inconsistencies (or checks) in Lithium.

That said, you are right, I can use an unsigned type in the signature of
DehoistArrayIndex (when I extract the value from the HConstant) and with deal
signed values only inside that function, and this will make the code cleaner.

 };
 
 
 class HLoadKeyedFastDoubleElement: public HTemplateInstruction<2> {
  public:
-  HLoadKeyedFastDoubleElement(HValue* elements, HValue* key) {
+  HLoadKeyedFastDoubleElement(HValue* elements, HValue* key) :

[Jakob Kummerow, 2012/05/08 13:46:26]

nit: the colon goes in the next line (see HLoadKeyedFastElement as an example)

[Massi, 2012/05/14 13:48:52]

Done.

+      index_offset_(0) {
     SetOperandAt(0, elements);
     SetOperandAt(1, key);
     set_representation(Representation::Double());
@@ -4002,6 +4006,8 @@ class HLoadKeyedFastDoubleElement: public HTemplateInstruction<2> {
 
   HValue* elements() { return OperandAt(0); }
   HValue* key() { return OperandAt(1); }
+  uint32_t index_offset() { return index_offset_; }
+  void SetIndexOffset(uint32_t index_offset) { index_offset_ = index_offset; }
 
   virtual Representation RequiredInputRepresentation(int index) {
     // The key is supposed to be Integer32.
@@ -4016,6 +4022,9 @@ class HLoadKeyedFastDoubleElement: public HTemplateInstruction<2> {
 
  protected:
   virtual bool DataEquals(HValue* other) { return true; }
+
+ private:
+  uint32_t index_offset_;
 };
 
 
@@ -4024,7 +4033,7 @@ class HLoadKeyedSpecializedArrayElement: public HTemplateInstruction<2> {
   HLoadKeyedSpecializedArrayElement(HValue* external_elements,
                                     HValue* key,
                                     ElementsKind elements_kind)
-      :  elements_kind_(elements_kind) {
+      :  elements_kind_(elements_kind), index_offset_(0) {
     SetOperandAt(0, external_elements);
     SetOperandAt(1, key);
     if (elements_kind == EXTERNAL_FLOAT_ELEMENTS ||
@@ -4052,6 +4061,8 @@ class HLoadKeyedSpecializedArrayElement: public HTemplateInstruction<2> {
   HValue* external_pointer() { return OperandAt(0); }
   HValue* key() { return OperandAt(1); }
   ElementsKind elements_kind() const { return elements_kind_; }
+  uint32_t index_offset() { return index_offset_; }
+  void SetIndexOffset(uint32_t index_offset) { index_offset_ = index_offset; }
 
   virtual Range* InferRange(Zone* zone);
 
@@ -4067,6 +4078,7 @@ class HLoadKeyedSpecializedArrayElement: public HTemplateInstruction<2> {
 
  private:
   ElementsKind elements_kind_;
+  uint32_t index_offset_;
 };
 
 
@@ -4192,7 +4204,7 @@ class HStoreKeyedFastElement: public HTemplateInstruction<3> {
  public:
   HStoreKeyedFastElement(HValue* obj, HValue* key, HValue* val,
                          ElementsKind elements_kind = FAST_ELEMENTS)
-      : elements_kind_(elements_kind) {
+      : elements_kind_(elements_kind), index_offset_(0) {
     SetOperandAt(0, obj);
     SetOperandAt(1, key);
     SetOperandAt(2, val);
@@ -4212,6 +4224,8 @@ class HStoreKeyedFastElement: public HTemplateInstruction<3> {
   bool value_is_smi() {
     return elements_kind_ == FAST_SMI_ONLY_ELEMENTS;
   }
+  uint32_t index_offset() { return index_offset_; }
+  void SetIndexOffset(uint32_t index_offset) { index_offset_ = index_offset; }
 
   bool NeedsWriteBarrier() {
     if (value_is_smi()) {
@@ -4227,6 +4241,7 @@ class HStoreKeyedFastElement: public HTemplateInstruction<3> {
 
  private:
   ElementsKind elements_kind_;
+  uint32_t index_offset_;
 };
 
 
@@ -4234,7 +4249,7 @@ class HStoreKeyedFastDoubleElement: public HTemplateInstruction<3> {
  public:
   HStoreKeyedFastDoubleElement(HValue* elements,
                                HValue* key,
-                               HValue* val) {
+                               HValue* val) : index_offset_(0) {
     SetOperandAt(0, elements);
     SetOperandAt(1, key);
     SetOperandAt(2, val);
@@ -4254,6 +4269,8 @@ class HStoreKeyedFastDoubleElement: public HTemplateInstruction<3> {
   HValue* elements() { return OperandAt(0); }
   HValue* key() { return OperandAt(1); }
   HValue* value() { return OperandAt(2); }
+  uint32_t index_offset() { return index_offset_; }
+  void SetIndexOffset(uint32_t index_offset) { index_offset_ = index_offset; }
 
   bool NeedsWriteBarrier() {
     return StoringValueNeedsWriteBarrier(value());
@@ -4264,6 +4281,9 @@ class HStoreKeyedFastDoubleElement: public HTemplateInstruction<3> {
   virtual void PrintDataTo(StringStream* stream);
 
   DECLARE_CONCRETE_INSTRUCTION(StoreKeyedFastDoubleElement)
+
+ private:
+  uint32_t index_offset_;
 };
 
 
@@ -4273,7 +4293,7 @@ class HStoreKeyedSpecializedArrayElement: public HTemplateInstruction<3> {
                                      HValue* key,
                                      HValue* val,
                                      ElementsKind elements_kind)
-      : elements_kind_(elements_kind) {
+      : elements_kind_(elements_kind), index_offset_(0) {
     SetGVNFlag(kChangesSpecializedArrayElements);
     SetOperandAt(0, external_elements);
     SetOperandAt(1, key);
@@ -4301,11 +4321,14 @@ class HStoreKeyedSpecializedArrayElement: public HTemplateInstruction<3> {
   HValue* key() { return OperandAt(1); }
   HValue* value() { return OperandAt(2); }
   ElementsKind elements_kind() const { return elements_kind_; }
+  uint32_t index_offset() { return index_offset_; }
+  void SetIndexOffset(uint32_t index_offset) { index_offset_ = index_offset; }
 
   DECLARE_CONCRETE_INSTRUCTION(StoreKeyedSpecializedArrayElement)
 
  private:
   ElementsKind elements_kind_;
+  uint32_t index_offset_;
 };