[csa] Add CSA::CallBuiltin and Builtins::CallableFor

src/builtins/builtins.cc

Index: src/builtins/builtins.cc
diff --git a/src/builtins/builtins.cc b/src/builtins/builtins.cc
index d642f20882d577e176118cafd1705ba0c71bb20e..e05556862ac0418cafff4bdaaf8773c221d38a0b 100644
--- a/src/builtins/builtins.cc
+++ b/src/builtins/builtins.cc
@@ -5,6 +5,7 @@
 #include "src/builtins/builtins.h"
 #include "src/api.h"
 #include "src/assembler-inl.h"
+#include "src/callable.h"
 #include "src/code-events.h"
 #include "src/compiler/code-assembler.h"
 #include "src/ic/ic-state.h"
@@ -275,6 +276,23 @@ Handle<Code> Builtins::OrdinaryToPrimitive(OrdinaryToPrimitiveHint hint) {
 }
 
 // static
+Callable Builtins::CallableFor(Isolate* isolate, Name name) {
+  switch (name) {
+#define CASE(Name, _, __, InterfaceDescriptor, ...)                      \
+  case k##Name: {                                                        \
+    Handle<Code> code(Code::cast(isolate->builtins()->builtins_[name])); \

[caitp, 2017/03/16 13:30:06]

Is there any way we could push args in excess of 4 to the stack? It would be
helpful for moving InternelPerformPromiseThen to a stub without doing extra type
checks and loads.

+    auto descriptor = InterfaceDescriptor##Descriptor(isolate);          \
+    return Callable(code, descriptor);                                   \
+  }
+    BUILTIN_LIST_TFS(CASE)
+#undef CASE
+    default:
+      UNREACHABLE();
+      return Callable(Handle<Code>::null(), VoidDescriptor(isolate));
+  }
+}
+
+// static
 const char* Builtins::name(int index) {
   switch (index) {
 #define CASE(Name, ...) \