[interpreter] Add basic framework for bytecode handler code generation.

src/compiler/linkage-impl.h

Index: src/compiler/linkage-impl.h
diff --git a/src/compiler/linkage-impl.h b/src/compiler/linkage-impl.h
index 5b638034c8cbeaf7e141eda55d0d71150ba3bdcf..eaac5a6687a616cec58181a3120be6c3087563c8 100644
--- a/src/compiler/linkage-impl.h
+++ b/src/compiler/linkage-impl.h
@@ -6,6 +6,7 @@
 #define V8_COMPILER_LINKAGE_IMPL_H_
 
 #include "src/code-stubs.h"
+#include "src/compiler/interpreter-assembler.h"
 #include "src/compiler/osr.h"
 
 namespace v8 {
@@ -233,18 +234,31 @@ class LinkageHelper {
         "c-call");
   }
 
-  static CallDescriptor* GetInterpreterDispatchDescriptor(
-      Zone* zone, const MachineSignature* msig) {
-    DCHECK_EQ(0, msig->parameter_count());
-    LocationSignature::Builder locations(zone, msig->return_count(),
-                                         msig->parameter_count());
-    AddReturnLocations(&locations);
+  static CallDescriptor* GetInterpreterDispatchDescriptor(Zone* zone,
+                                                          bool needs_return) {
+    int return_count = needs_return ? 1 : 0;
+    MachineSignature::Builder types(zone, return_count, 2);
+    LocationSignature::Builder locations(zone, return_count, 2);
+
+    DCHECK_EQ(0, InterpreterAssembler::kBytecodePointerParameter);

[oth, 2015/07/15 13:22:01]

One line comment explaining types purpose (reserving registers).

[rmcilroy, 2015/07/15 16:55:58]

Done.

+    types.AddParam(kMachPtr);
+    locations.AddParam(regloc(LinkageTraits::InterpreterBytecodePointerReg()));
+
+    DCHECK_EQ(1, InterpreterAssembler::kDispatchTablePointerParameter);
+    types.AddParam(kMachPtr);
+    locations.AddParam(regloc(LinkageTraits::InterpreterDispatchTableReg()));
+
+    if (needs_return) {
+      types.AddReturn(kMachAnyTagged);
+      AddReturnLocations(&locations);
+    }
+
     LinkageLocation target_loc = LinkageLocation::AnyRegister();
     return new (zone) CallDescriptor(          // --
         CallDescriptor::kInterpreterDispatch,  // kind
         kMachNone,                             // target MachineType
         target_loc,                            // target location
-        msig,                                  // machine_sig
+        types.Build(),                         // machine_sig
         locations.Build(),                     // location_sig
         0,                                     // js_parameter_count
         Operator::kNoProperties,               // properties