* function.h (struct function): New field calls_constant_p.
(current_function_calls_constant_p): New macro for above.
* function.c (prepare_function_start): Initialize calls_eh_return
and calls_constant_p.
* builtins.c (expand_builtin_constant_p): Set calls_constant_p.
* toplev.c (rest_of_compilation): Only call purge_builtin_constant_p
when the current_function_calls_constant_p.
* integrate.c (expand_inline_function): Set calls_constant_p if
the function being inlined has calls_constant_p set.
From-SVN: r61786
