Improve stores to global variables.

src/ia32/virtual-frame-ia32.cc

Index: src/ia32/virtual-frame-ia32.cc
===================================================================
--- src/ia32/virtual-frame-ia32.cc	(revision 3920)
+++ src/ia32/virtual-frame-ia32.cc	(working copy)
@@ -948,47 +948,38 @@
 }
 
 
-Result VirtualFrame::CallStoreIC() {
-  // Name, value, and receiver are on top of the frame.  The IC
-  // expects name in ecx, value in eax, and receiver in edx.
+Result VirtualFrame::CallStoreIC(Handle<String> name, bool is_contextual) {
+  // Value and (if not contextual) receiver are on top of the frame.
+  //  The IC expects name in ecx, value in eax, and receiver in edx.
   Handle<Code> ic(Builtins::builtin(Builtins::StoreIC_Initialize));
-  Result name = Pop();
   Result value = Pop();
-  Result receiver = Pop();
-  PrepareForCall(0, 0);
+  if (is_contextual) {
+    PrepareForCall(0, 0);
+    value.ToRegister(eax);
+    __ mov(edx, Operand(esi, Context::SlotOffset(Context::GLOBAL_INDEX)));
+    __ mov(ecx, name);
+  } else {
+    Result receiver = Pop();
+    PrepareForCall(0, 0);
 
-  // Optimized for case in which name is a constant value.
-  if (name.is_register() && (name.reg().is(edx) || name.reg().is(eax))) {
-    if (!is_used(ecx)) {
-      name.ToRegister(ecx);
-    } else if (!is_used(ebx)) {
-      name.ToRegister(ebx);
+    if (value.is_register() && value.reg().is(edx)) {
+      if (receiver.is_register() && receiver.reg().is(eax)) {
+        // Wrong registers.
+        __ xchg(eax, edx);
+      } else {
+        // Register eax is free for value, which frees edx for receiver.
+        value.ToRegister(eax);
+        receiver.ToRegister(edx);
+      }
     } else {
-      ASSERT(!is_used(edi));  // Only three results are live, so edi is free.
-      name.ToRegister(edi);
-    }
-  }
-  // Now name is not in edx or eax, so we can fix them, then move name to ecx.
-  if (value.is_register() && value.reg().is(edx)) {
-    if (receiver.is_register() && receiver.reg().is(eax)) {
-      // Wrong registers.
-      __ xchg(eax, edx);
-    } else {
-      // Register eax is free for value, which frees edx for receiver.
-      value.ToRegister(eax);
+      // Register edx is free for receiver, which guarantees eax is free for
+      // value.
       receiver.ToRegister(edx);
+      value.ToRegister(eax);
     }
-  } else {
-    // Register edx is free for receiver, which guarantees eax is free for
-    // value.
-    receiver.ToRegister(edx);
-    value.ToRegister(eax);
   }
-  // Receiver and value are in the right place, so ecx is free for name.
-  name.ToRegister(ecx);
-  name.Unuse();
+  __ mov(ecx, name);
   value.Unuse();
-  receiver.Unuse();
   return RawCallCodeObject(ic, RelocInfo::CODE_TARGET);
 }