The Gambit Scheme->C compiler has an option to generate more efficient
code if it knows that all tail and sibling calls in the generated C code
will be optimized. If gcc does not, however, optimize a tail or sibling
call, the generated C code may be incorrect (depending on circumstances).
So I would like to add a warning enabled by -Wdisabled-optimization so
that if -foptimize-sibling-calls is given and a tail or sibling call is
not optimized, then a warning is triggered.
I don't quite know where to place the warning. It would be good if
there were one piece of code to identify all tail and sibling calls, and
then another piece that decides whether the optimization can be performed.
I see code in gcc/tree-tailcall.cc
suitable_for_tail_opt_p
suitable_for_tail_call_opt_p
which are called by
tree_optimize_tail_calls_1
which takes an argument
opt_tailcalls
and it's called in one place with opt_tailcalls true and in another
place with opt_tailcalls false.
So I'm losing the plot here.
There is other code dealing with tail calls in gcc/calls.cc I don't seem
to understand at all.
Any advice?
Brad
