On Mon, 6 Mar 2023 at 10:11, Richard Biener <rguent...@suse.de> wrote: > > The following adds two RAII classes, one for mpz_t and one for mpfr_t > making object lifetime management easier. Both formerly require > explicit initialization with {mpz,mpfr}_init and release with > {mpz,mpfr}_clear. > > I've converted two example places (where lifetime is trivial). > > I've sofar only build cc1 with the change. Any comments? > > Thanks, > Richard. > > * system.h (class auto_mpz): New, > * realmpfr.h (class auto_mpfr): Likewise. > * fold-const-call.cc (do_mpfr_arg1): Use auto_mpfr. > (do_mpfr_arg2): Likewise. > * tree-ssa-loop-niter.cc (bound_difference): Use auto_mpz; > --- > gcc/fold-const-call.cc | 8 ++------ > gcc/realmpfr.h | 15 +++++++++++++++ > gcc/system.h | 14 ++++++++++++++ > gcc/tree-ssa-loop-niter.cc | 10 +--------- > 4 files changed, 32 insertions(+), 15 deletions(-) > > diff --git a/gcc/fold-const-call.cc b/gcc/fold-const-call.cc > index 43819c1f984..fa0b287cc8a 100644 > --- a/gcc/fold-const-call.cc > +++ b/gcc/fold-const-call.cc > @@ -130,14 +130,12 @@ do_mpfr_arg1 (real_value *result, > > int prec = format->p; > mpfr_rnd_t rnd = format->round_towards_zero ? MPFR_RNDZ : MPFR_RNDN; > - mpfr_t m; > > - mpfr_init2 (m, prec); > + auto_mpfr m (prec); > mpfr_from_real (m, arg, MPFR_RNDN); > mpfr_clear_flags (); > bool inexact = func (m, m, rnd); > bool ok = do_mpfr_ckconv (result, m, inexact, format); > - mpfr_clear (m); > > return ok; > } > @@ -224,14 +222,12 @@ do_mpfr_arg2 (real_value *result, > > int prec = format->p; > mpfr_rnd_t rnd = format->round_towards_zero ? MPFR_RNDZ : MPFR_RNDN; > - mpfr_t m; > > - mpfr_init2 (m, prec); > + auto_mpfr m (prec); > mpfr_from_real (m, arg1, MPFR_RNDN); > mpfr_clear_flags (); > bool inexact = func (m, arg0.to_shwi (), m, rnd); > bool ok = do_mpfr_ckconv (result, m, inexact, format); > - mpfr_clear (m); > > return ok; > } > diff --git a/gcc/realmpfr.h b/gcc/realmpfr.h > index 5e032c05f25..2db2ecc94d4 100644 > --- a/gcc/realmpfr.h > +++ b/gcc/realmpfr.h > @@ -24,6 +24,21 @@ > #include <mpfr.h> > #include <mpc.h> > > +class auto_mpfr > +{ > +public: > + auto_mpfr () { mpfr_init (m_mpfr); } > + explicit auto_mpfr (mpfr_prec_t prec) { mpfr_init2 (m_mpfr, prec); } > + ~auto_mpfr () { mpfr_clear (m_mpfr); } > + > + operator mpfr_t& () { return m_mpfr; }
This implicit conversion makes the following mistake possible, if code is incorrectly converted to use it: auto_mpfr m (prec); // ... mpfr_clear (m); // oops! You could prevent that by adding this to the class body: friend void mpfr_clear (auto_mpfr&) = delete; This will be a better match for calls to mpfr_clear(m) than using the implicit conversion then calling the real function, and will give an error if used: auto.cc:20:13: error: use of deleted function 'void mpfr_clear(auto_mpfr&)' This deleted friend will not be a candidate for calls to mpfr_clear with an argument of any other type, only for calls with an argument of type auto_mpfr. > + > + auto_mpfr (const auto_mpfr &) = delete; This class has an implicit-defined assignment operator, which would result in a leaks and double-frees. You should add: auto_mpfr &operator=(const auto_mpfr &) = delete; This ensures it can't becopied by construction or assignment. The same two comments apply to auto_mpz.