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-rw-r--r--js/src/jit-test/tests/basic/bug972961.js40
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diff --git a/js/src/jit-test/tests/basic/bug972961.js b/js/src/jit-test/tests/basic/bug972961.js
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+++ b/js/src/jit-test/tests/basic/bug972961.js
@@ -0,0 +1,40 @@
+// Bug 972961 - Test compiler with very long chains of property accesses
+
+// Return true if we can compile a chain of n property accesses,
+// false if we cannot. Throw if compilation fails in an unexpected way.
+function test(n) {
+ print("testing " + n);
+ try {
+ eval('if (false) {' + Array(n).join(("a.")) + 'a}');
+ } catch (exc) {
+ // Expected outcome if the expression is too deeply nested is an InternalError.
+ if (!(exc instanceof InternalError))
+ throw exc;
+ print(exc.message);
+ return false;
+ }
+ print("no exception");
+ return true;
+}
+
+// Find out how long a chain is enough to break the compiler.
+var n = 4, LIMIT = 0x000fffff;
+var lo = 1, hi = 1;
+while (n <= LIMIT && test(n)) {
+ lo = n;
+ n *= 4;
+}
+
+// Using binary search, find a pass/fail boundary (in order to
+// test the edge case).
+if (n <= LIMIT) {
+ hi = n;
+ while (lo !== hi) {
+ var mid = Math.floor((lo + hi) / 2);
+ if (test(mid))
+ lo = mid + 1;
+ else
+ hi = mid;
+ }
+ print((lo - 1) + " attributes should be enough for anyone");
+}