Truncate rather than round to nearest when performing float-to-integer...

test/cctest/test-api.cc

Index: test/cctest/test-api.cc
===================================================================
--- test/cctest/test-api.cc	(revision 6406)
+++ test/cctest/test-api.cc	(working copy)
@@ -10587,6 +10587,33 @@
     CHECK_EQ(0, result->Int32Value());
     CHECK_EQ(0,
              i::Smi::cast(jsobj->GetElement(5)->ToObjectChecked())->value());
+
+    // Check truncation behavior of integral arrays.
+    const char* unsigned_data =
+        "var source_data = [0.6, 10.6];"
+        "var expected_results = [0, 10];";
+    const char* signed_data =
+        "var source_data = [0.6, 10.6, -0.6, -10.6];"
+        "var expected_results = [0, 10, 0, -10];";
+    bool is_unsigned =
+        (array_type == v8::kExternalUnsignedByteArray ||
+         array_type == v8::kExternalUnsignedShortArray ||
+         array_type == v8::kExternalUnsignedIntArray);
+
+    i::OS::SNPrintF(test_buf,
+                    "%s"
+                    "var all_passed = true;"
+                    "for (var i = 0; i < source_data.length; i++) {"
+                    "  for (var j = 0; j < 8; j++) {"
+                    "    ext_array[j] = source_data[i];"
+                    "  }"
+                    "  all_passed = all_passed &&"
+                    "               (ext_array[5] == expected_results[i]);"
+                    "}"
+                    "all_passed;",
+                    (is_unsigned ? unsigned_data : signed_data));
+    result = CompileRun(test_buf.start());
+    CHECK_EQ(true, result->BooleanValue());
   }
 
   result = CompileRun("ext_array[3] = 33;"