Promote and inflate string slices during scavenging GC.

test/mjsunit/string-slices.js

Index: test/mjsunit/string-slices.js
diff --git a/test/mjsunit/string-slices.js b/test/mjsunit/string-slices.js
index 8cc1f81e774fe6b8449555b90a3d5bba868f4db2..eb33e013d8a71c9089fa942313cd67082bb8258c 100755
--- a/test/mjsunit/string-slices.js
+++ b/test/mjsunit/string-slices.js
@@ -25,7 +25,7 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Flags: --string-slices --expose-externalize-string
+// Flags: --string-slices --expose-externalize-string --expose-gc
 
 var s = 'abcdefghijklmn';
 assertEquals(s, s.substr());
@@ -113,7 +113,6 @@ var cache = [];
 for (var i = 0; i < 1000; i++) {
   var z = x.substring(i % xl);
   assertEquals(xl - (i % xl), z.length);
-  cache.push(z);
 }
 
 
@@ -127,30 +126,39 @@ x += x;
 x += x;  // 2^10
 x += x;
 x += x;
+x += x;
+x += x;
+x += x;
+x += x;
+x += x;
 var xl = x.length;
 var cache = [];
 for (var i = 0; i < 1000; i++) {
   var z = x.substring(i % xl);
   assertEquals(xl - (i % xl), z.length);
-  cache.push(z);
 }
 
 // Substring of substring.
 var cache = [];
 var last = x;
-var offset = 0;
-for (var i = 0; i < 64; i++) {
-  var z = last.substring(i);
+for (var i = 0; i < 100000; i++) {
+  var z = last.substring(1);
   last = z;
   cache.push(z);
-  offset += i;
 }
-for (var i = 63; i >= 0; i--) {
+
+// Fill up new space with junk and then invoke GC.
+var fill = [];
+for (var i = 0; i < 1000000; i++) {
+  fill.push(i + " ");
+}
+gc(true);
+
+for (var i = 100000; i > 0; i--) {
   var z = cache.pop();
   assertTrue(/\u2028123456789ABCDEF/.test(z));
-  assertEquals(xl - offset, z.length);
-  assertEquals(x.charAt(i*(i+1)/2), z.charAt(0));
-  offset -= i;
+  assertEquals(xl - i, z.length);
+  assertEquals(x.charAt(i), z.charAt(0));
 }
 
 // Test charAt for different strings.