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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/fold-const.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/fold-const.h')
| -rw-r--r-- | gcc/fold-const.h | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/gcc/fold-const.h b/gcc/fold-const.h index e833019..818c3d5 100644 --- a/gcc/fold-const.h +++ b/gcc/fold-const.h @@ -27,9 +27,11 @@ extern int folding_initializer; /* Convert between trees and native memory representation. */ extern int native_encode_expr (const_tree, unsigned char *, int, int off = -1); extern int native_encode_initializer (tree, unsigned char *, int, - int off = -1); + int off = -1, unsigned char * = nullptr); extern tree native_interpret_expr (tree, const unsigned char *, int); extern bool can_native_interpret_type_p (tree); +extern tree native_interpret_aggregate (tree, const unsigned char *, int, int); +extern tree find_bitfield_repr_type (int, int); extern void shift_bytes_in_array_left (unsigned char *, unsigned int, unsigned int); extern void shift_bytes_in_array_right (unsigned char *, unsigned int, |