I may take back my implication of the exp() function.  Adding suitable
debug printf()s changes the execution of the code such that it works 
with -O, but fails with -O -fcaller-saves.  Removal of some of these 
printf()s (specifically in the end of the patch() routine) produces
code that fails with -O but works with -O0.

So is it a library problem, a codegen issue, buggy code, or ???
Any help appreciated.  FreeBSD running gcc 2.6.3 produces expected
results.  My test case is: a.out 17 8 0

-j