Convert some compiler passes to preserve valid def-use chains.

runtime/vm/intermediate_language.h

Index: runtime/vm/intermediate_language.h
diff --git a/runtime/vm/intermediate_language.h b/runtime/vm/intermediate_language.h
index 1d70a291fb7b5f59b0aa6dd7475c2d8e15a2a291..5be9f08650879ec40631a16d73970d32b47fefc4 100644
--- a/runtime/vm/intermediate_language.h
+++ b/runtime/vm/intermediate_language.h
@@ -366,10 +366,11 @@ class Instruction : public ZoneAllocated {
   // Call instructions override this function and return the number of
   // pushed arguments.
   virtual intptr_t ArgumentCount() const = 0;
-  virtual PushArgumentInstr* ArgumentAt(intptr_t index) const {
+  virtual PushArgumentInstr* PushArgumentAt(intptr_t index) const {
     UNREACHABLE();
     return NULL;
-  };
+  }
+  inline Definition* ArgumentAt(intptr_t index) const;

[Vyacheslav Egorov (Google), 2013/02/08 16:44:49]

I like the naming cleanup.

 
   // Returns true, if this instruction can deoptimize.
   virtual bool CanDeoptimize() const = 0;
@@ -1408,6 +1409,11 @@ class PushArgumentInstr : public Definition {
 };
 
 
+inline Definition* Instruction::ArgumentAt(intptr_t index) const {
+  return PushArgumentAt(index)->value()->definition();
+}
+
+
 class ReturnInstr : public TemplateInstruction<1> {
  public:
   ReturnInstr(intptr_t token_pos, Value* value)
@@ -2075,7 +2081,7 @@ class ClosureCallInstr : public TemplateDefinition<0> {
   intptr_t token_pos() const { return ast_node_.token_pos(); }
 
   virtual intptr_t ArgumentCount() const { return arguments_->length(); }
-  PushArgumentInstr* ArgumentAt(intptr_t index) const {
+  virtual PushArgumentInstr* PushArgumentAt(intptr_t index) const {
     return (*arguments_)[index];
   }
 
@@ -2137,7 +2143,7 @@ class InstanceCallInstr : public TemplateDefinition<0> {
   const String& function_name() const { return function_name_; }
   Token::Kind token_kind() const { return token_kind_; }
   virtual intptr_t ArgumentCount() const { return arguments_->length(); }
-  PushArgumentInstr* ArgumentAt(intptr_t index) const {
+  virtual PushArgumentInstr* PushArgumentAt(intptr_t index) const {
     return (*arguments_)[index];
   }
   const Array& argument_names() const { return argument_names_; }
@@ -2185,8 +2191,8 @@ class PolymorphicInstanceCallInstr : public TemplateDefinition<0> {
   virtual intptr_t ArgumentCount() const {
     return instance_call()->ArgumentCount();
   }
-  PushArgumentInstr* ArgumentAt(intptr_t index) const {
-    return instance_call()->ArgumentAt(index);
+  virtual PushArgumentInstr* PushArgumentAt(intptr_t index) const {
+    return instance_call()->PushArgumentAt(index);
   }
 
   DECLARE_INSTRUCTION(PolymorphicInstanceCall)
@@ -2490,7 +2496,7 @@ class StaticCallInstr : public TemplateDefinition<0> {
   intptr_t token_pos() const { return token_pos_; }
 
   virtual intptr_t ArgumentCount() const { return arguments_->length(); }
-  PushArgumentInstr* ArgumentAt(intptr_t index) const {
+  virtual PushArgumentInstr* PushArgumentAt(intptr_t index) const {
     return (*arguments_)[index];
   }
 
@@ -2950,7 +2956,7 @@ class AllocateObjectInstr : public TemplateDefinition<0> {
   virtual RawAbstractType* CompileType() const;
 
   virtual intptr_t ArgumentCount() const { return arguments_->length(); }
-  PushArgumentInstr* ArgumentAt(intptr_t index) const {
+  virtual PushArgumentInstr* PushArgumentAt(intptr_t index) const {
     return (*arguments_)[index];
   }
 
@@ -3018,7 +3024,7 @@ class CreateArrayInstr : public TemplateDefinition<1> {
         type_(type) {
 #if defined(DEBUG)
     for (int i = 0; i < ArgumentCount(); ++i) {
-      ASSERT(ArgumentAt(i) != NULL);
+      ASSERT(PushArgumentAt(i) != NULL);
     }
     ASSERT(element_type != NULL);
     ASSERT(type_.IsZoneHandle());
@@ -3032,9 +3038,11 @@ class CreateArrayInstr : public TemplateDefinition<1> {
   virtual RawAbstractType* CompileType() const;
 
   virtual intptr_t ArgumentCount() const { return arguments_->length(); }
+  virtual PushArgumentInstr* PushArgumentAt(intptr_t i) const {
+    return (*arguments_)[i];
+  }
 
   intptr_t token_pos() const { return token_pos_; }
-  PushArgumentInstr* ArgumentAt(intptr_t i) const { return (*arguments_)[i]; }
   const AbstractType& type() const { return type_; }
   Value* element_type() const { return inputs_[0]; }
 
@@ -3071,7 +3079,7 @@ class CreateClosureInstr : public TemplateDefinition<0> {
   const Function& function() const { return function_; }
 
   virtual intptr_t ArgumentCount() const { return arguments_->length(); }
-  PushArgumentInstr* ArgumentAt(intptr_t index) const {
+  virtual PushArgumentInstr* PushArgumentAt(intptr_t index) const {
     return (*arguments_)[index];
   }