896048cf43
The following patch adds __builtin_bit_cast builtin, similarly to clang or MSVC which implement std::bit_cast using such an builtin too. It checks the various std::bit_cast requirements, when not constexpr evaluated acts pretty much like VIEW_CONVERT_EXPR of the source argument to the destination type and the hardest part is obviously the constexpr evaluation. I've left out PDP11 handling of those, couldn't figure out how exactly are bitfields laid out there 2020-12-03 Jakub Jelinek <jakub@redhat.com> PR libstdc++/93121 * fold-const.h (native_encode_initializer): Add mask argument defaulted to nullptr. (find_bitfield_repr_type): Declare. (native_interpret_aggregate): Declare. * fold-const.c (find_bitfield_repr_type): New function. (native_encode_initializer): Add mask argument and support for filling it. Handle also some bitfields without integral DECL_BIT_FIELD_REPRESENTATIVE. (native_interpret_aggregate): New function. * gimple-fold.h (clear_type_padding_in_mask): Declare. * gimple-fold.c (struct clear_padding_struct): Add clear_in_mask member. (clear_padding_flush): Handle buf->clear_in_mask. (clear_padding_union): Copy clear_in_mask. Don't error if buf->clear_in_mask is set. (clear_padding_type): Don't error if buf->clear_in_mask is set. (clear_type_padding_in_mask): New function. (gimple_fold_builtin_clear_padding): Set buf.clear_in_mask to false. * doc/extend.texi (__builtin_bit_cast): Document. * c-common.h (enum rid): Add RID_BUILTIN_BIT_CAST. * c-common.c (c_common_reswords): Add __builtin_bit_cast. * cp-tree.h (cp_build_bit_cast): Declare. * cp-tree.def (BIT_CAST_EXPR): New tree code. * cp-objcp-common.c (names_builtin_p): Handle RID_BUILTIN_BIT_CAST. (cp_common_init_ts): Handle BIT_CAST_EXPR. * cxx-pretty-print.c (cxx_pretty_printer::postfix_expression): Likewise. * parser.c (cp_parser_postfix_expression): Handle RID_BUILTIN_BIT_CAST. * semantics.c (cp_build_bit_cast): New function. * tree.c (cp_tree_equal): Handle BIT_CAST_EXPR. (cp_walk_subtrees): Likewise. * pt.c (tsubst_copy): Likewise. * constexpr.c (check_bit_cast_type, cxx_eval_bit_cast): New functions. (cxx_eval_constant_expression): Handle BIT_CAST_EXPR. (potential_constant_expression_1): Likewise. * cp-gimplify.c (cp_genericize_r): Likewise. * g++.dg/cpp2a/bit-cast1.C: New test. * g++.dg/cpp2a/bit-cast2.C: New test. * g++.dg/cpp2a/bit-cast3.C: New test. * g++.dg/cpp2a/bit-cast4.C: New test. * g++.dg/cpp2a/bit-cast5.C: New test. |
||
|---|---|---|
| config | ||
| contrib | ||
| fixincludes | ||
| gcc | ||
| gnattools | ||
| gotools | ||
| include | ||
| INSTALL | ||
| intl | ||
| libada | ||
| libatomic | ||
| libbacktrace | ||
| libcc1 | ||
| libcpp | ||
| libdecnumber | ||
| libffi | ||
| libgcc | ||
| libgfortran | ||
| libgo | ||
| libgomp | ||
| libhsail-rt | ||
| libiberty | ||
| libitm | ||
| libobjc | ||
| liboffloadmic | ||
| libphobos | ||
| libquadmath | ||
| libsanitizer | ||
| libssp | ||
| libstdc++-v3 | ||
| libvtv | ||
| lto-plugin | ||
| maintainer-scripts | ||
| zlib | ||
| .dir-locals.el | ||
| .gitattributes | ||
| .gitignore | ||
| ABOUT-NLS | ||
| ar-lib | ||
| ChangeLog | ||
| ChangeLog.jit | ||
| ChangeLog.tree-ssa | ||
| compile | ||
| config-ml.in | ||
| config.guess | ||
| config.rpath | ||
| config.sub | ||
| configure | ||
| configure.ac | ||
| COPYING | ||
| COPYING3 | ||
| COPYING3.LIB | ||
| COPYING.LIB | ||
| COPYING.RUNTIME | ||
| depcomp | ||
| install-sh | ||
| libtool-ldflags | ||
| libtool.m4 | ||
| lt~obsolete.m4 | ||
| ltgcc.m4 | ||
| ltmain.sh | ||
| ltoptions.m4 | ||
| ltsugar.m4 | ||
| ltversion.m4 | ||
| MAINTAINERS | ||
| Makefile.def | ||
| Makefile.in | ||
| Makefile.tpl | ||
| missing | ||
| mkdep | ||
| mkinstalldirs | ||
| move-if-change | ||
| multilib.am | ||
| README | ||
| symlink-tree | ||
| test-driver | ||
| ylwrap | ||
This directory contains the GNU Compiler Collection (GCC). The GNU Compiler Collection is free software. See the files whose names start with COPYING for copying permission. The manuals, and some of the runtime libraries, are under different terms; see the individual source files for details. The directory INSTALL contains copies of the installation information as HTML and plain text. The source of this information is gcc/doc/install.texi. The installation information includes details of what is included in the GCC sources and what files GCC installs. See the file gcc/doc/gcc.texi (together with other files that it includes) for usage and porting information. An online readable version of the manual is in the files gcc/doc/gcc.info*. See http://gcc.gnu.org/bugs/ for how to report bugs usefully. Copyright years on GCC source files may be listed using range notation, e.g., 1987-2012, indicating that every year in the range, inclusive, is a copyrightable year that could otherwise be listed individually.