Do integer mod via sum-of-digits technique. This benefits the date

src/arm/macro-assembler-arm.cc

 // Copyright 2006-2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1668 matching lines @@
                      scratch2,
                      gc_required,
                      TAG_OBJECT);
 
   // Store heap number map in the allocated object.
   AssertRegisterIsRoot(heap_number_map, Heap::kHeapNumberMapRootIndex);
   str(heap_number_map, FieldMemOperand(result, HeapObject::kMapOffset));
 }
 
 
-void MacroAssembler::CountLeadingZeros(Register source,
-                                       Register scratch,
-                                       Register zeros) {
+void MacroAssembler::CountLeadingZeros(Register zeros,   // Answer.
+                                       Register source,  // Input.
+                                       Register scratch) {
+  ASSERT(!zeros.is(source) || !source.is(zeros));
+  ASSERT(!zeros.is(scratch));
+  ASSERT(!scratch.is(ip));
+  ASSERT(!source.is(ip));
+  ASSERT(!zeros.is(ip));
 #ifdef CAN_USE_ARMV5_INSTRUCTIONS
   clz(zeros, source);  // This instruction is only supported after ARM5.
 #else
   mov(zeros, Operand(0));
-  mov(scratch, source);
+  Move(scratch, source);
   // Top 16.
   tst(scratch, Operand(0xffff0000));
   add(zeros, zeros, Operand(16), LeaveCC, eq);
   mov(scratch, Operand(scratch, LSL, 16), LeaveCC, eq);
   // Top 8.
   tst(scratch, Operand(0xff000000));
   add(zeros, zeros, Operand(8), LeaveCC, eq);
   mov(scratch, Operand(scratch, LSL, 8), LeaveCC, eq);
   // Top 4.
   tst(scratch, Operand(0xf0000000));
@@ skipping 129 matching lines @@
 
 void CodePatcher::Emit(Address addr) {
   masm()->emit(reinterpret_cast<Instr>(addr));
 }
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM