| Message ID | alpine.DEB.2.02.1907101722500.29179@grove.saclay.inria.fr |
|---|---|
| State | New |
| Headers | show |
| Series | [C++] Don't fold __builtin_constant_p prematurely | expand |
Adding a C++ maintainer in Cc: https://gcc.gnu.org/ml/gcc-patches/2019-07/msg00808.html On Wed, 10 Jul 2019, Marc Glisse wrote: > Hello, > > this avoids folding __builtin_constant_p to 0 early when we are not forced to > do so. Clearly this has an effect, since it uncovered a bug in wi::lshift, > fixed today ;-) > > I wasn't sure about using |= or just =, the first one seemed more > conservative. > > Bootstrap+regtest on x86_64-pc-linux-gnu. > > 2019-07-11 Marc Glisse <marc.glisse@inria.fr> > > gcc/cp/ > * constexpr.c (cxx_eval_builtin_function_call): Only set > force_folding_builtin_constant_p if manifestly_const_eval. > > gcc/testsuite/ > * g++.dg/pr85746.C: New file.
Ping On Tue, 16 Jul 2019, Marc Glisse wrote: > Adding a C++ maintainer in Cc: > https://gcc.gnu.org/ml/gcc-patches/2019-07/msg00808.html > > On Wed, 10 Jul 2019, Marc Glisse wrote: > >> Hello, >> >> this avoids folding __builtin_constant_p to 0 early when we are not forced >> to do so. Clearly this has an effect, since it uncovered a bug in >> wi::lshift, fixed today ;-) >> >> I wasn't sure about using |= or just =, the first one seemed more >> conservative. >> >> Bootstrap+regtest on x86_64-pc-linux-gnu. >> >> 2019-07-11 Marc Glisse <marc.glisse@inria.fr> >> >> gcc/cp/ >> * constexpr.c (cxx_eval_builtin_function_call): Only set >> force_folding_builtin_constant_p if manifestly_const_eval. >> >> gcc/testsuite/ >> * g++.dg/pr85746.C: New file.
On Fri, 2 Aug 2019, Marc Glisse wrote: > Ping > > On Tue, 16 Jul 2019, Marc Glisse wrote: > >> Adding a C++ maintainer in Cc: >> https://gcc.gnu.org/ml/gcc-patches/2019-07/msg00808.html >> >> On Wed, 10 Jul 2019, Marc Glisse wrote: >> >>> Hello, >>> >>> this avoids folding __builtin_constant_p to 0 early when we are not forced >>> to do so. Clearly this has an effect, since it uncovered a bug in >>> wi::lshift, fixed today ;-) >>> >>> I wasn't sure about using |= or just =, the first one seemed more >>> conservative. >>> >>> Bootstrap+regtest on x86_64-pc-linux-gnu. >>> >>> 2019-07-11 Marc Glisse <marc.glisse@inria.fr> >>> >>> gcc/cp/ >>> * constexpr.c (cxx_eval_builtin_function_call): Only set >>> force_folding_builtin_constant_p if manifestly_const_eval. >>> >>> gcc/testsuite/ >>> * g++.dg/pr85746.C: New file.
Ping On Tue, 3 Sep 2019, Marc Glisse wrote: > On Fri, 2 Aug 2019, Marc Glisse wrote: > >> Ping >> >> On Tue, 16 Jul 2019, Marc Glisse wrote: >> >>> Adding a C++ maintainer in Cc: >>> https://gcc.gnu.org/ml/gcc-patches/2019-07/msg00808.html >>> >>> On Wed, 10 Jul 2019, Marc Glisse wrote: >>> >>>> Hello, >>>> >>>> this avoids folding __builtin_constant_p to 0 early when we are not >>>> forced to do so. Clearly this has an effect, since it uncovered a bug in >>>> wi::lshift, fixed today ;-) >>>> >>>> I wasn't sure about using |= or just =, the first one seemed more >>>> conservative. >>>> >>>> Bootstrap+regtest on x86_64-pc-linux-gnu. >>>> >>>> 2019-07-11 Marc Glisse <marc.glisse@inria.fr> >>>> >>>> gcc/cp/ >>>> * constexpr.c (cxx_eval_builtin_function_call): Only set >>>> force_folding_builtin_constant_p if manifestly_const_eval. >>>> >>>> gcc/testsuite/ >>>> * g++.dg/pr85746.C: New file.
Ping https://gcc.gnu.org/ml/gcc-patches/2019-07/msg00808.html with one more potential reviewer in Cc. On Wed, 11 Sep 2019, Marc Glisse wrote: > Ping > > On Tue, 3 Sep 2019, Marc Glisse wrote: > >> On Fri, 2 Aug 2019, Marc Glisse wrote: >> >>> Ping >>> >>> On Tue, 16 Jul 2019, Marc Glisse wrote: >>> >>>> Adding a C++ maintainer in Cc: >>>> https://gcc.gnu.org/ml/gcc-patches/2019-07/msg00808.html >>>> >>>> On Wed, 10 Jul 2019, Marc Glisse wrote: >>>> >>>>> Hello, >>>>> >>>>> this avoids folding __builtin_constant_p to 0 early when we are not >>>>> forced to do so. Clearly this has an effect, since it uncovered a bug in >>>>> wi::lshift, fixed today ;-) >>>>> >>>>> I wasn't sure about using |= or just =, the first one seemed more >>>>> conservative. >>>>> >>>>> Bootstrap+regtest on x86_64-pc-linux-gnu. >>>>> >>>>> 2019-07-11 Marc Glisse <marc.glisse@inria.fr> >>>>> >>>>> gcc/cp/ >>>>> * constexpr.c (cxx_eval_builtin_function_call): Only set >>>>> force_folding_builtin_constant_p if manifestly_const_eval. >>>>> >>>>> gcc/testsuite/ >>>>> * g++.dg/pr85746.C: New file. > >
OK, thanks. On 9/27/19 2:07 PM, Marc Glisse wrote: > Ping https://gcc.gnu.org/ml/gcc-patches/2019-07/msg00808.html > with one more potential reviewer in Cc. > > On Wed, 11 Sep 2019, Marc Glisse wrote: > >> Ping >> >> On Tue, 3 Sep 2019, Marc Glisse wrote: >> >>> On Fri, 2 Aug 2019, Marc Glisse wrote: >>> >>>> Ping >>>> >>>> On Tue, 16 Jul 2019, Marc Glisse wrote: >>>> >>>>> Adding a C++ maintainer in Cc: >>>>> https://gcc.gnu.org/ml/gcc-patches/2019-07/msg00808.html >>>>> >>>>> On Wed, 10 Jul 2019, Marc Glisse wrote: >>>>> >>>>>> Hello, >>>>>> >>>>>> this avoids folding __builtin_constant_p to 0 early when we are >>>>>> not forced to do so. Clearly this has an effect, since it >>>>>> uncovered a bug in wi::lshift, fixed today ;-) >>>>>> >>>>>> I wasn't sure about using |= or just =, the first one seemed more >>>>>> conservative. >>>>>> >>>>>> Bootstrap+regtest on x86_64-pc-linux-gnu. >>>>>> >>>>>> 2019-07-11 Marc Glisse <marc.glisse@inria.fr> >>>>>> >>>>>> gcc/cp/ >>>>>> * constexpr.c (cxx_eval_builtin_function_call): Only set >>>>>> force_folding_builtin_constant_p if manifestly_const_eval. >>>>>> >>>>>> gcc/testsuite/ >>>>>> * g++.dg/pr85746.C: New file. >> >> >
Index: gcc/cp/constexpr.c =================================================================== --- gcc/cp/constexpr.c (revision 273356) +++ gcc/cp/constexpr.c (working copy) @@ -1248,21 +1248,21 @@ cxx_eval_builtin_function_call (const co &dummy1, &dummy2); } if (bi_const_p) /* For __builtin_constant_p, fold all expressions with constant values even if they aren't C++ constant-expressions. */ args[i] = cp_fold_rvalue (args[i]); } bool save_ffbcp = force_folding_builtin_constant_p; - force_folding_builtin_constant_p = true; + force_folding_builtin_constant_p |= ctx->manifestly_const_eval; tree save_cur_fn = current_function_decl; /* Return name of ctx->call->fundef->decl for __builtin_FUNCTION (). */ if (fndecl_built_in_p (fun, BUILT_IN_FUNCTION) && ctx->call && ctx->call->fundef) current_function_decl = ctx->call->fundef->decl; new_call = fold_builtin_call_array (EXPR_LOCATION (t), TREE_TYPE (t), CALL_EXPR_FN (t), nargs, args); current_function_decl = save_cur_fn; force_folding_builtin_constant_p = save_ffbcp; Index: gcc/testsuite/g++.dg/pr85746.C =================================================================== --- gcc/testsuite/g++.dg/pr85746.C (nonexistent) +++ gcc/testsuite/g++.dg/pr85746.C (working copy) @@ -0,0 +1,10 @@ +/* { dg-do compile } */ +/* { dg-options "-O -fdump-tree-gimple" } */ + +int f(int a,int b){ + // The front-end should not fold this to 0. + int c = __builtin_constant_p(a < b); + return c; +} + +/* { dg-final { scan-tree-dump "__builtin_constant_p" "gimple" } } */