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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 // modification, are permitted provided that the following conditions are
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 //
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 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 // Flags: --allow-natives-syntax
 
-// The below test function was generated from part of a WebKit layout
-// test library setup routine: fast/canvas/webgl/resources/pnglib.js
-
-function test(crc32) {
-  for (var i = 0; i < 256; i++) {
-    var c = i;
-    for (var j = 0; j < 8; j++) {
-      if (c & 1) {
-        c = -306674912 ^ ((c >> 1) & 0x7fffffff);
-      } else {
-        c = (c >> 1) & 0x7fffffff;
-      }
-    }
-    crc32[i] = c;
-  }
+// stubbed version of ToNumber
+function ToNumber(x) {
+    return 311;

[Jakob Kummerow, 2013/05/16 13:18:57]

nit: indentation

[titzer, 2013/05/16 14:28:44]

Done.

 }
 
-var a = [0.5];
-for (var i = 0; i < 256; ++i) a[i] = i;
+// Reduced version of String.fromCharCode;
+// does not actually do the same calculation but exhibits untagging bug

[Jakob Kummerow, 2013/05/16 13:18:57]

nit: trailing full stop please

+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;
+  }
 
-test([0.5]);
-test(a);
-%OptimizeFunctionOnNextCall(test);
-test(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;
+}
+
+StringFromCharCode(0xFFF, 0xFFF);
+StringFromCharCode(0x7C, 0x7C);
+%OptimizeFunctionOnNextCall(StringFromCharCode)
+StringFromCharCode(0x7C, 0x7C);
+StringFromCharCode(0xFFF, 0xFFF);