arm: Fix Smi check in SubStringStub::Generate

src/arm/code-stubs-arm.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "v8.h"
 
 #if V8_TARGET_ARCH_ARM
 
 #include "bootstrapper.h"
 #include "code-stubs.h"
@@ skipping 3373 matching lines @@
   // We want to bailout to runtime here if From is negative.  In that case, the
   // next instruction is not executed and we fall through to bailing out to
   // runtime.
   // Executed if both r2 and r3 are untagged integers.
   __ sub(r2, r2, Operand(r3), SetCC, cc);
   // One of the above un-smis or the above SUB could have set N==1.
   __ b(mi, &runtime);  // Either "from" or "to" is not an smi, or from > to.
 
   // Make sure first argument is a string.
   __ ldr(r0, MemOperand(sp, kStringOffset));
-  // Do a JumpIfSmi, but fold its jump into the subsequent string test.
-  __ SmiTst(r0);
-  Condition is_string = masm->IsObjectStringType(r0, r1, ne);
-  ASSERT(is_string == eq);
+  __ JumpIfSmi(r0, &runtime);
+  Condition is_string = masm->IsObjectStringType(r0, r1);
   __ b(NegateCondition(is_string), &runtime);
 
   Label single_char;
   __ cmp(r2, Operand(1));
   __ b(eq, &single_char);
 
   // Short-cut for the case of trivial substring.
   Label return_r0;
   // r0: original string
   // r2: result string length
@@ skipping 1717 matching lines @@
                               MemOperand(fp, 6 * kPointerSize),
                               NULL);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM