Fix code gen bug on arm and mips; SeqStringSetChar overwrites a register; Add better default PrintD…

test/mjsunit/regress/regress-seqstrsetchar-ex1.js

 // Copyright 2013 the V8 project authors. All rights reserved.
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 // Flags: --allow-natives-syntax
 
-function TestNonSmiArrayLength() {
-  function f(a) {
-    return a.length+1;
+// stubbed version of ToNumber
+function ToNumber(x) {
+  return 311;
+}
+
+// Reduced version of String.fromCharCode;
+// does not actually do the same calculation but exhibits untagging bug
+function StringFromCharCode(code) {
+  var n = %_ArgumentsLength();
+  var one_byte = %NewString(n, true);
+  var i;
+  for (i = 0; i < n; i++) {
+    var code = %_Arguments(i);
+    if (!%_IsSmi(code)) code = ToNumber(code) & 0xffff;
+    if (code > 0xff) break;
   }
 
-  var a = [];
-  a.length = 0xFFFF;
-  assertSame(0x10000, f(a));
-  assertSame(0x10000, f(a));
-
-  %OptimizeFunctionOnNextCall(f);
-  a.length = 0xFFFFFFFF;
-  assertSame(0x100000000, f(a));
+  var two_byte = %NewString(n - i, false);
+  for (var j = 0; i < n; i++, j++) {
+    var code = %_Arguments(i);
+    %_TwoByteSeqStringSetChar(two_byte, j, code);
+  }
+  return one_byte + two_byte;
 }
 
-TestNonSmiArrayLength();
+StringFromCharCode(0xFFF, 0xFFF);
+StringFromCharCode(0x7C, 0x7C);
+%OptimizeFunctionOnNextCall(StringFromCharCode);
+StringFromCharCode(0x7C, 0x7C);
+StringFromCharCode(0xFFF, 0xFFF);