On Tue, 2023-08-01 at 20:20 +0200, Jose E. Marchesi via Gcc wrote: > > > > 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). > > > > clang supports a musttail attribute that you use in return > > statements. > > But AFAIK GCC doesn't support it. It would be nice if it did. > > I looked around a little. > > The GCC tree nodes for call expressions can be annotated as to > require > tail call optimization: > > /* Set on a CALL_EXPR if the call has been marked as requiring tail > call > optimization for correctness. */ > #define CALL_EXPR_MUST_TAIL_CALL(NODE) \ > (CALL_EXPR_CHECK (NODE)->base.static_flag) > > And this is checked in many different places in calls.cc. But at the > moment the only way to set that flag is via a compiler plugin.
Or from libgccjit. FWIW I added it to support Scheme from libgccjit; see this patch kit: https://gcc.gnu.org/ml/gcc-patches/2016-05/msg01287.html Perhaps there's a case for a frontend attribute for this. Dave > An > example of such a plugin is part of the GCC testsuite: > > testsuite/gcc.dg/plugin/must_tail_call_plugin.c > > It may be possible to use a similar plugin in your Scheme-to-C > compiler... >
