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The delete-memcpy-with-non-trivial-types patch exposed many instances
of this problem:
src/gdb/btrace.h: In function ‘btrace_insn_s* VEC_btrace_insn_s_quick_insert(VEC_btrace_insn_s*, unsigned int, const btrace_insn_s*, const char*, unsigned int)’:
src/gdb/common/vec.h:948:62: error: use of deleted function ‘void* memmove(T*, const U*, size_t) [with T = btrace_insn; U = btrace_insn; <template-parameter-1-3> = void; size_t = long unsigned int]’
memmove (slot_ + 1, slot_, (vec_->num++ - ix_) * sizeof (T)); \
^
src/gdb/common/vec.h:436:1: note: in expansion of macro ‘DEF_VEC_FUNC_O’
DEF_VEC_FUNC_O(T) \
^
src/gdb/btrace.h:84:1: note: in expansion of macro ‘DEF_VEC_O’
DEF_VEC_O (btrace_insn_s);
^
[...]
src/gdb/common/vec.h:1060:31: error: use of deleted function ‘void* memcpy(T*, const U*, size_t) [with T = btrace_insn; U = btrace_insn; <template-parameter-1-3> = void; size_t = long unsigned int]’
sizeof (T) * vec2_->num); \
^
src/gdb/common/vec.h:437:1: note: in expansion of macro ‘DEF_VEC_ALLOC_FUNC_O’
DEF_VEC_ALLOC_FUNC_O(T) \
^
src/gdb/btrace.h:84:1: note: in expansion of macro ‘DEF_VEC_O’
DEF_VEC_O (btrace_insn_s);
^
So, VECs (given it's C roots) rely on memcpy/memcpy of VEC elements to
be well defined, in order to grow/reallocate its internal elements
array. This means that we can only put trivially copyable types in
VECs. E.g., if a type requires using a custom copy/move ctor to
relocate, then we can't put it in a VEC (so we use std::vector
instead). But, as shown above, we're violating that requirement.
btrace_insn is currently not trivially copyable, because it contains
an enum_flags field, and that is itself not trivially copyable. This
patch corrects that, by simply removing the user-provided copy
constructor and assignment operator. The compiler-generated versions
work just fine.
Note that std::vector relies on std::is_trivially_copyable too to know
whether it can reallocate its elements with memcpy/memmove instead of
having to call copy/move ctors and dtors, so if we have types in
std::vectors that weren't trivially copyable because of enum_flags,
this will make such vectors more efficient.
gdb/ChangeLog:
2017-04-25 Pedro Alves <palves@redhat.com>
* common/enum-flags.h (enum_flags): Don't implement copy ctor and
assignment operator.
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... so that we don't need to do it manually, and potentially forget.
For example, this allows to do:
my_flags flags;
...
flags |= some_flag;
gdb/ChangeLog:
* common/enum-flags.h (enum_flags::enum_flags): Initialize
m_enum_value to 0 in default constructor.
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This applies the second part of GDB's End of Year Procedure, which
updates the copyright year range in all of GDB's files.
gdb/ChangeLog:
Update copyright year range in all GDB files.
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gdb/ChangeLog:
Update year range in copyright notice of all files.
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This patch fixes C++ build errors like this:
/home/pedro/gdb/mygit/cxx-convertion/src/gdb/linux-tdep.c:1126:35: error: invalid conversion from ‘int’ to ‘filterflags’ [-fpermissive]
| COREFILTER_HUGETLB_PRIVATE);
^
This is a case of enums used as bit flags. Unlike "regular" enums,
these values are supposed to be or'ed together. However, in C++, the
type of "(ENUM1 | ENUM2)" is int, and you then can't assign an int to
an enum variable without a cast. That means that this:
enum foo_flags flags = 0;
if (...)
flags |= FOO_FLAG1;
if (...)
flags |= FOO_FLAG2;
... would have to be written as:
enum foo_flags flags = (enum foo_flags) 0;
if (...)
flags = (enum foo_flags) (flags | FOO_FLAG1);
if (...)
flags = (enum foo_flags) (flags | FOO_FLAG2);
which is ... ugly. Alternatively, we'd have to use an int for the
variable's type, which isn't ideal either.
This patch instead adds an "enum flags" class. "enum flags" are
exactly the enums where the values are bits that are meant to be ORed
together.
This allows writing code like the below, while with raw enums this
would fail to compile without casts to enum type at the assignments to
'f':
enum some_flag
{
flag_val1 = 1 << 1,
flag_val2 = 1 << 2,
flag_val3 = 1 << 3,
flag_val4 = 1 << 4,
};
DEF_ENUM_FLAGS_TYPE(enum some_flag, some_flags)
some_flags f = flag_val1 | flag_val2;
f |= flag_val3;
It's also possible to assign literal zero to an enum flags variable
(meaning, no flags), dispensing either adding an awkward explicit "no
value" value to the enumeration or the cast to assignments from 0.
For example:
some_flags f = 0;
f |= flag_val3 | flag_val4;
Note that literal integers other than zero do fail to compile:
some_flags f = 1; // error
C is still supported -- DEF_ENUM_FLAGS_TYPE is just a typedef in that
case.
gdb/ChangeLog:
2015-11-17 Pedro Alves <palves@redhat.com>
* btrace.h: Include common/enum-flags.h.
(btrace_insn_flags): Define.
(struct btrace_insn) <flags>: Change type.
(btrace_function_flags): Define.
(struct btrace_function) <flags>: Change type.
(btrace_thread_flags): Define.
(struct btrace_thread_info) <flags>: Change type.
* c-exp.y (token_flags): Rename to ...
(token_flag): ... this.
(token_flags): Define.
(struct token) <flags>: Change type.
* common/enum-flags.h: New file.
* compile/compile-c-types.c (convert_qualified): Change type of
'quals' local.
* compile/compile-internal.h: Include "common/enum-flags.h".
(gcc_qualifiers_flags): Define.
* completer.c (enum reg_completer_targets): Rename to ...
(enum reg_completer_target): ... this.
(reg_completer_targets): Define.
(reg_or_group_completer_1): Change type of 'targets' parameter.
* disasm.c (do_mixed_source_and_assembly_deprecated): Change type
of 'psl_flags' local.
(do_mixed_source_and_assembly): Change type of 'psl_flags' local.
* infrun.c: Include "common/enum-flags.h".
(enum step_over_what): Rename to ...
(enum step_over_what_flag): ... this.
(step_over_what): Change type.
(start_step_over): Change type of 'step_what' local.
(thread_still_needs_step_over): Now returns a step_over_what.
Adjust.
(keep_going_pass_signal): Change type of 'step_what' local.
* linux-tdep.c: Include "common/enum-flags.h".
(enum filterflags): Rename to ...
(enum filter_flag): ... this.
(filter_flags): Define.
(dump_mapping_p): Change type of 'filterflags' parameter.
(linux_find_memory_regions_full): Change type of 'filterflags'
local.
(linux_find_memory_regions_full): Pass the address of an unsigned
int to sscanf instead of the address of an enum.
* record-btrace.c (btrace_print_lines): Change type of local
'psl_flags'.
(btrace_call_history): Replace 'flags' parameter
with 'int_flags' parameter. Adjust.
(record_btrace_call_history, record_btrace_call_history_range)
(record_btrace_call_history_from): Rename 'flags' parameter to
'int_flags'. Use record_print_flags.
* record.h: Include "common/enum-flags.h".
(record_print_flags): Define.
* source.c: Include "common/enum-flags.h".
(print_source_lines_base, print_source_lines): Change type of
flags parameter.
* symtab.h: Include "common/enum-flags.h".
(enum print_source_lines_flags): Rename to ...
(enum print_source_lines_flag): ... this.
(print_source_lines_flags): Define.
(print_source_lines): Change prototype.
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