[Atomics] code stubs for atomic operations

src/compiler/code-stub-assembler.h

Index: src/compiler/code-stub-assembler.h
diff --git a/src/compiler/code-stub-assembler.h b/src/compiler/code-stub-assembler.h
index 6c2e299de95974c3a9502689b5398cbda08100bf..154985999feb660ea7d948acbf445ce7d475ed2b 100644
--- a/src/compiler/code-stub-assembler.h
+++ b/src/compiler/code-stub-assembler.h
@@ -9,6 +9,7 @@
 // Do not include anything from src/compiler here!
 #include "src/allocation.h"
 #include "src/builtins.h"
+#include "src/machine-type.h"
 #include "src/runtime/runtime.h"
 
 namespace v8 {
@@ -43,7 +44,13 @@ class CodeStubAssembler {
   Node* HeapConstant(Handle<HeapObject> object);
   Node* BooleanConstant(bool value);
 
+  // Memory Operations.
+  Node* Load(MachineType rep, Node* base);
+  Node* Load(MachineType rep, Node* base, Node* index);
+
   Node* Parameter(int value);
+  Node* StackArg(Node* num_args, int value);
+  Node* StackArgOrUndefined(Node* num_args, int value);

[Jarin, 2016/02/03 09:04:07]

You should not need this, just use Parameter.

[binji, 2016/02/03 22:09:02]

This doesn't seem to work, perhaps I'm doing it wrong? Parameter() seems to
return the descriptor registers, in order. (e.g. Parameter(0) returns the value
of rax, which is argc for the function call). But the builtin has all of its
parameters stored on the stack. Is there an easy way to automatically fill the
registers with these stack values?

[Jarin, 2016/02/04 05:28:01]

We looked at this with Benedikt and it looks like the problem is that the
linkage uses the BuiltinDescriptor to describe the parameters, and that only
defines the register parameters. 

Instead, we need to initialize CodeStubAssembler with JSCallDesriptor. Could you
try to define a new constructor that calls Linkage::JSCallDescriptor (rather
than  Linkage::GetStubCallDescriptor)?

In any case, thanks for exploring this, you are awesome!

[binji, 2016/02/05 02:53:01]

Thanks, that works. Done!

   void Return(Node* value);
 
   // Tag and untag Smi values.