A64: Move the dispatching logic of the decoder to a separate class.

BUG=none
R=ulan@chromium.org, rodolph.perfetta@arm.com
LOG=n

Review URL: https://codereview.chromium.org/181233002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19561 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/a64/decoder-a64.cc

@@ -37,6 +37,73 @@
 namespace v8 {
 namespace internal {
 
+
+void DispatchingDecoderVisitor::AppendVisitor(DecoderVisitor* new_visitor) {
+  visitors_.remove(new_visitor);
+  visitors_.push_front(new_visitor);
+}
+
+
+void DispatchingDecoderVisitor::PrependVisitor(DecoderVisitor* new_visitor) {
+  visitors_.remove(new_visitor);
+  visitors_.push_back(new_visitor);
+}
+
+
+void DispatchingDecoderVisitor::InsertVisitorBefore(
+    DecoderVisitor* new_visitor, DecoderVisitor* registered_visitor) {
+  visitors_.remove(new_visitor);
+  std::list<DecoderVisitor*>::iterator it;
+  for (it = visitors_.begin(); it != visitors_.end(); it++) {
+    if (*it == registered_visitor) {
+      visitors_.insert(it, new_visitor);
+      return;
+    }
+  }
+  // We reached the end of the list. The last element must be
+  // registered_visitor.
+  ASSERT(*it == registered_visitor);
+  visitors_.insert(it, new_visitor);
+}
+
+
+void DispatchingDecoderVisitor::InsertVisitorAfter(
+    DecoderVisitor* new_visitor, DecoderVisitor* registered_visitor) {
+  visitors_.remove(new_visitor);
+  std::list<DecoderVisitor*>::iterator it;
+  for (it = visitors_.begin(); it != visitors_.end(); it++) {
+    if (*it == registered_visitor) {
+      it++;
+      visitors_.insert(it, new_visitor);
+      return;
+    }
+  }
+  // We reached the end of the list. The last element must be
+  // registered_visitor.
+  ASSERT(*it == registered_visitor);
+  visitors_.push_back(new_visitor);
+}
+
+
+void DispatchingDecoderVisitor::RemoveVisitor(DecoderVisitor* visitor) {
+  visitors_.remove(visitor);
+}
+
+
+#define DEFINE_VISITOR_CALLERS(A)                                \
+  void DispatchingDecoderVisitor::Visit##A(Instruction* instr) { \
+    if (!(instr->Mask(A##FMask) == A##Fixed)) {                  \
+      ASSERT(instr->Mask(A##FMask) == A##Fixed);                 \
+    }                                                            \
+    std::list<DecoderVisitor*>::iterator it;                     \
+    for (it = visitors_.begin(); it != visitors_.end(); it++) {  \
+      (*it)->Visit##A(instr);                                    \
+    }                                                            \
+  }
+VISITOR_LIST(DEFINE_VISITOR_CALLERS)
+#undef DEFINE_VISITOR_CALLERS
+
+
 // Top-level instruction decode function.
 void Decoder::Decode(Instruction *instr) {
   if (instr->Bits(28, 27) == 0) {
@@ -116,58 +183,6 @@ void Decoder::Decode(Instruction *instr) {
 }
 
 
-void Decoder::AppendVisitor(DecoderVisitor* new_visitor) {
-  visitors_.remove(new_visitor);
-  visitors_.push_front(new_visitor);
-}
-
-
-void Decoder::PrependVisitor(DecoderVisitor* new_visitor) {
-  visitors_.remove(new_visitor);
-  visitors_.push_back(new_visitor);
-}
-
-
-void Decoder::InsertVisitorBefore(DecoderVisitor* new_visitor,
-                                  DecoderVisitor* registered_visitor) {
-  visitors_.remove(new_visitor);
-  std::list<DecoderVisitor*>::iterator it;
-  for (it = visitors_.begin(); it != visitors_.end(); it++) {
-    if (*it == registered_visitor) {
-      visitors_.insert(it, new_visitor);
-      return;
-    }
-  }
-  // We reached the end of the list. The last element must be
-  // registered_visitor.
-  ASSERT(*it == registered_visitor);
-  visitors_.insert(it, new_visitor);
-}
-
-
-void Decoder::InsertVisitorAfter(DecoderVisitor* new_visitor,
-                                 DecoderVisitor* registered_visitor) {
-  visitors_.remove(new_visitor);
-  std::list<DecoderVisitor*>::iterator it;
-  for (it = visitors_.begin(); it != visitors_.end(); it++) {
-    if (*it == registered_visitor) {
-      it++;
-      visitors_.insert(it, new_visitor);
-      return;
-    }
-  }
-  // We reached the end of the list. The last element must be
-  // registered_visitor.
-  ASSERT(*it == registered_visitor);
-  visitors_.push_back(new_visitor);
-}
-
-
-void Decoder::RemoveVisitor(DecoderVisitor* visitor) {
-  visitors_.remove(visitor);
-}
-
-
 void Decoder::DecodePCRelAddressing(Instruction* instr) {
   ASSERT(instr->Bits(27, 24) == 0x0);
   // We know bit 28 is set, as <b28:b27> = 0 is filtered out at the top level
@@ -707,20 +722,6 @@ void Decoder::DecodeAdvSIMDDataProcessing(Instruction* instr) {
 }
 
 
-#define DEFINE_VISITOR_CALLERS(A)                                              \
-  void Decoder::Visit##A(Instruction *instr) {                                 \
-    if (!(instr->Mask(A##FMask) == A##Fixed)) {                                \
-      ASSERT(instr->Mask(A##FMask) == A##Fixed);                             \
-    }                                                                          \
-    std::list<DecoderVisitor*>::iterator it;                                   \
-    for (it = visitors_.begin(); it != visitors_.end(); it++) {                \
-      (*it)->Visit##A(instr);                                                  \
-    }                                                                          \
-  }
-VISITOR_LIST(DEFINE_VISITOR_CALLERS)
-#undef DEFINE_VISITOR_CALLERS
-
-
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_A64

src/a64/decoder-a64.h

@@ -97,13 +97,11 @@ class DecoderVisitor {
 };
 
 
-class Decoder {
+// A visitor that dispatches to a list of visitors.
+class DispatchingDecoderVisitor : public DecoderVisitor {
  public:
-  Decoder() {}
-
-  // Top-level instruction decoder function. Decodes an instruction and calls
-  // the visitor functions registered with the Decoder class.
-  void Decode(Instruction *instr);
+  DispatchingDecoderVisitor() {}
+  virtual ~DispatchingDecoderVisitor() {}
 
   // Register a new visitor class with the decoder.
   // Decode() will call the corresponding visitor method from all registered
@@ -138,6 +136,20 @@ class Decoder {
   VISITOR_LIST(DECLARE)
   #undef DECLARE
 
+ private:
+  // Visitors are registered in a list.
+  std::list<DecoderVisitor*> visitors_;
+};
+
+
+class Decoder : public DispatchingDecoderVisitor {
+ public:
+  Decoder() {}
+
+  // Top-level instruction decoder function. Decodes an instruction and calls
+  // the visitor functions registered with the Decoder class.
+  void Decode(Instruction *instr);
+
  private:
   // Decode the PC relative addressing instruction, and call the corresponding
   // visitors.
@@ -188,9 +200,6 @@ class Decoder {
   // tree, and call the corresponding visitors.
   // On entry, instruction bits 27:25 = 0x7.
   void DecodeAdvSIMDDataProcessing(Instruction* instr);
-
-  // Visitors are registered in a list.
-  std::list<DecoderVisitor*> visitors_;
 };