Fix HType handling for HConstant with external references.

We cannot use set_type() with HType::None() in the HConstant
constructor, since set_type() asserts that the new type is a
subtype of the previous one, but HType::None() is not a subtype
of HType::Tagged() which is the initial type set by the HValue
constructor.

This patch adds an optional type parameter to the HValue,
HInstruction and HTemplateInstruction constructors.

R=titzer@chromium.org

Review URL: https://codereview.chromium.org/21317004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15980 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/hydrogen-instructions.cc

@@ -2741,7 +2741,8 @@ HConstant::HConstant(double double_value,
 
 
 HConstant::HConstant(ExternalReference reference)
-  : has_smi_value_(false),
+  : HTemplateInstruction(HType::None()),
+    has_smi_value_(false),
     has_int32_value_(false),
     has_double_value_(false),
     has_external_reference_value_(true),
@@ -2750,7 +2751,6 @@ HConstant::HConstant(ExternalReference reference)
     is_cell_(false),
     boolean_value_(true),
     external_reference_value_(reference) {
-  set_type(HType::None());
   Initialize(Representation::External());
 }
 

src/hydrogen-instructions.h

@@ -873,12 +873,13 @@ class HValue: public ZoneObject {
     HYDROGEN_ABSTRACT_INSTRUCTION_LIST(DECLARE_PREDICATE)
   #undef DECLARE_PREDICATE
 
-  HValue() : block_(NULL),
-             id_(kNoNumber),
-             type_(HType::Tagged()),
-             use_list_(NULL),
-             range_(NULL),
-             flags_(0) {}
+  HValue(HType type = HType::Tagged())
+      : block_(NULL),
+        id_(kNoNumber),
+        type_(type),
+        use_list_(NULL),
+        range_(NULL),
+        flags_(0) {}
   virtual ~HValue() {}
 
   HBasicBlock* block() const { return block_; }
@@ -1343,8 +1344,9 @@ class HInstruction: public HValue {
   DECLARE_ABSTRACT_INSTRUCTION(Instruction)
 
  protected:
-  HInstruction()
-      : next_(NULL),
+  HInstruction(HType type = HType::Tagged())
+      : HValue(type),
+        next_(NULL),
         previous_(NULL),
         position_(RelocInfo::kNoPosition) {
     SetGVNFlag(kDependsOnOsrEntries);
@@ -1375,6 +1377,8 @@ class HTemplateInstruction : public HInstruction {
   HValue* OperandAt(int i) const { return inputs_[i]; }
 
  protected:
+  HTemplateInstruction(HType type = HType::Tagged()) : HInstruction(type) {}
+
   void InternalSetOperandAt(int i, HValue* value) { inputs_[i] = value; }
 
  private: