+
+#ifdef __xlC__ /* "eXceLlent C compiler" ?! */
+#if __xlC__ >= 1200
+/* IBM's C compiler option `-O3' is too aggressive.
+ We recommend instead the combination `-O3 -qstrict', which seems safe.
+
+ cc -O3 miscompiles at least two functions. From IBM's docs:
+
+ IBM> -qstrict turns off the following optimizations:
+
+ IBM> Performing code motion and scheduling on computations such as loads
+ IBM> and floating-point computations that may trigger an exception.
+
+ Nevertheless, we try to work with these compiler options. */
+#pragma option_override (bytecount_to_charcount, "opt(strict,yes)")
+#pragma option_override (Fexpand_file_name, "opt(strict,yes)")
+#endif /* recent IBM C compiler */
+#endif /* IBM's C compiler */
+