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| author | Jakub Jelinek <jakub@redhat.com> | 2020-12-03 15:46:54 +0100 |
|---|---|---|
| committer | Jakub Jelinek <jakub@redhat.com> | 2020-12-03 15:46:54 +0100 |
| commit | 896048cf43d5eb21ab7c16553bb9d13b0f890b81 (patch) | |
| tree | 3d929f74e3ad0cd70a86d101744be4a961a57450 /gcc/gimple-fold.h | |
| parent | 341035a54aa8954c66b0492f366b8c65fdb34299 (diff) | |
| download | gcc-896048cf43d5eb21ab7c16553bb9d13b0f890b81.zip gcc-896048cf43d5eb21ab7c16553bb9d13b0f890b81.tar.gz gcc-896048cf43d5eb21ab7c16553bb9d13b0f890b81.tar.bz2 | |
c++: Add __builtin_bit_cast to implement std::bit_cast [PR93121]
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.
Diffstat (limited to 'gcc/gimple-fold.h')
| -rw-r--r-- | gcc/gimple-fold.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/gcc/gimple-fold.h b/gcc/gimple-fold.h index a131e36..f0f43f6 100644 --- a/gcc/gimple-fold.h +++ b/gcc/gimple-fold.h @@ -35,6 +35,7 @@ extern tree maybe_fold_and_comparisons (tree, enum tree_code, tree, tree, enum tree_code, tree, tree); extern tree maybe_fold_or_comparisons (tree, enum tree_code, tree, tree, enum tree_code, tree, tree); +extern void clear_type_padding_in_mask (tree, unsigned char *); extern bool optimize_atomic_compare_exchange_p (gimple *); extern void fold_builtin_atomic_compare_exchange (gimple_stmt_iterator *); extern bool arith_overflowed_p (enum tree_code, const_tree, const_tree, |