MIPS: Branch delay slot and other optimizations.

src/mips/builtins-mips.cc

Index: src/mips/builtins-mips.cc
diff --git a/src/mips/builtins-mips.cc b/src/mips/builtins-mips.cc
index 09a99243872014c09aea4000d214fb0e6c7eecec..60fc72feb6a84ed7a8ab02b6544178ea69de63b6 100644
--- a/src/mips/builtins-mips.cc
+++ b/src/mips/builtins-mips.cc
@@ -67,9 +67,11 @@ void Builtins::Generate_Adaptor(MacroAssembler* masm,
     ASSERT(extra_args == NO_EXTRA_ARGUMENTS);
   }
 
-  // JumpToExternalReference expects a0 to contain the number of arguments
+  // JumpToExternalReference expects s0 to contain the number of arguments
   // including the receiver and the extra arguments.
-  __ Addu(a0, a0, Operand(num_extra_args + 1));
+  __ Addu(s0, a0, num_extra_args + 1);
+  __ sll(s1, s0, kPointerSizeLog2);
+  __ Subu(s1, s1, kPointerSize);
   __ JumpToExternalReference(ExternalReference(id, masm->isolate()));
 }