Some functions related to the handling of registers in frames accept
"this frame", for which we want to read or write the register values,
while other functions accept "the next frame", which is the frame next
to that. The later is needed because we sometimes need to read register
values for a frame that does not exist yet (usually when trying to
unwind that frame-to-be).
value_of_register and value_of_register_lazy both take "this frame",
even if what they ultimately want internally is "the next frame". This
is annoying if you are in a spot that currently has "the next frame" and
need to call one of these functions (which happens later in this
series). You need to get the previous frame only for those functions to
get the next frame again. This is more manipulations, more chances of
mistake.
I propose to change these functions (and a few more functions in the
subsequent patches) to operate on "the next frame". Things become a bit
less awkward when all these functions agree on which frame they take.
So, in this patch, change value_of_register_lazy and value_of_register
to take "the next frame" instead of "this frame". This adds a lot of
get_next_frame_sentinel_okay, but if we convert the user registers API
to also use "the next frame" instead of "this frame", it will get simple
again.
Change-Id: Iaa24815e648fbe5ae3c214c738758890a91819cd
Reviewed-By: John Baldwin <jhb@FreeBSD.org>
This changes gdb to use the C++17 [[fallthrough]] attribute rather
than special comments.
This was mostly done by script, but I neglected a few spellings and so
also fixed it up by hand.
I suspect this fixes the bug mentioned below, by switching to a
standard approach that, presumably, clang supports.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=23159
Approved-By: John Baldwin <jhb@FreeBSD.org>
Approved-By: Luis Machado <luis.machado@arm.com>
Approved-By: Pedro Alves <pedro@palves.net>
This patch removes all uses of to_string(const std::string_view&) and
use the std::string ctor or implicit conversion from std::string_view to
std::string instead.
A later patch will remove this gdb::to_string while removing
gdbsupport/gdb_string_view.h.
Change-Id: I877cde557a0727be7b0435107e3c7a2aac165895
Approved-By: Tom Tromey <tom@tromey.com>
Approved-By: Pedro Alves <pedro@palves.net>
Given that GDB now requires a C++17, replace all uses of
gdb::string_view with std::string_view.
This change has mostly been done automatically:
- gdb::string_view -> std::string_view
- #include "gdbsupport/gdb_string_view.h" -> #include <string_view>
One things which got brought up during review is that gdb::stging_view
does support being built from "nullptr" while std::sting_view does not.
Two places are manually adjusted to account for this difference:
gdb/tui/tui-io.c:tui_getc_1 and
gdbsupport/format.h:format_piece::format_piece.
The above automatic change transformed
"gdb::to_string (const gdb::string_view &)" into
"gdb::to_string (const std::string_view &)". The various direct users
of this function are now explicitly including
"gdbsupport/gdb_string_view.h". A later patch will remove the users of
gdb::to_string.
The implementation and tests of gdb::string_view are unchanged, they will
be removed in a following patch.
Change-Id: Ibb806a7e9c79eb16a55c87c6e41ad396fecf0207
Approved-By: Tom Tromey <tom@tromey.com>
Approved-By: Pedro Alves <pedro@palves.net>
Since GDB now requires C++17, we don't need the internally maintained
gdb::optional implementation. This patch does the following replacing:
- gdb::optional -> std::optional
- gdb::in_place -> std::in_place
- #include "gdbsupport/gdb_optional.h" -> #include <optional>
This change has mostly been done automatically. One exception is
gdbsupport/thread-pool.* which did not use the gdb:: prefix as it
already lives in the gdb namespace.
Change-Id: I19a92fa03e89637bab136c72e34fd351524f65e9
Approved-By: Tom Tromey <tom@tromey.com>
Approved-By: Pedro Alves <pedro@palves.net>
I noticed a comment by an include and remembered that I think these
don't really provide much value -- sometimes they are just editorial,
and sometimes they are obsolete. I think it's better to just remove
them. Tested by rebuilding.
Approved-By: Andrew Burgess <aburgess@redhat.com>
eval_op_ternop is only used by the implementation of
ternop_slice_operation. While working on another series, it was
convenient for me to merge this function into its only caller.
Reviewed-by: Kevin Buettner <kevinb@redhat.com>
array_operation::evaluate has variables named "tem2" and "tem3". This
patch replaces one with a better name, and entirely removes the other.
Reviewed-by: John Baldwin <jhb@FreeBSD.org>
Approved-By: Simon Marchi <simon.marchi@efficios.com>
value_array requires the passed-in bounds to match the length of the
array_view it is given. This patch removes the redundant "highbound"
parameter.
Reviewed-by: John Baldwin <jhb@FreeBSD.org>
Approved-By: Simon Marchi <simon.marchi@efficios.com>
This removes yet another redundant variable from
array_operation::evaluate -- only one index is needed.
Reviewed-by: John Baldwin <jhb@FreeBSD.org>
Approved-By: Simon Marchi <simon.marchi@efficios.com>
In array_operation::evaluate, 'idx' and 'tem' are redundant in one
branch. This patch merges them, using the clearer name.
Reviewed-by: John Baldwin <jhb@FreeBSD.org>
Approved-By: Simon Marchi <simon.marchi@efficios.com>
This hoists the array bounds check in array_operation::evaluate to
before the loop.
Reviewed-by: John Baldwin <jhb@FreeBSD.org>
Approved-By: Simon Marchi <simon.marchi@efficios.com>
This changes array_operation::evaluate to declare the 'tem' variable
in the loop header, rather than at the top of the function. This is
cleaner and easier to reason about. I also changed 'nargs' to be
'const'.
Reviewed-by: John Baldwin <jhb@FreeBSD.org>
Approved-By: Simon Marchi <simon.marchi@efficios.com>
This changes value_array to accept an array view. I also replaced an
alloca with a std::vector in array_operation::evaluate. This function
can work on any size of array, so it seems bad to use alloca.
Reviewed-by: John Baldwin <jhb@FreeBSD.org>
Approved-By: Simon Marchi <simon.marchi@efficios.com>
This patch adds a new parser_flags type and changes the parser APIs to
use it rather than a collection of 'int' and 'bool'. More flags will
be added in subsquent patches.
This changes field_is_static to be a method on struct field, and
updates all the callers. Most of this patch was written by script.
Regression tested on x86-64 Fedora 36.
binop_promote currently only handles integer sizes up to
builtin_long_long. However, this may not handle 128-bit types.
Simplify this code, unify the C and non-C (but not OpenCL, as I don't
know how to test this) cases, and handle 128-bit integers as well.
This still doesn't exactly follow C or C++ rules. This could be
implemented, but if so, I think it makes more sense as a C-specific
expression node.
This removes deprecated_lval_hack and the VALUE_LVAL macro, replacing
all uses with a call to value::lval.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
This introduces the set_lval method on value, one step toward removing
deprecated_lval_hack. Ultimately I think the goal should be for some
of these set_* methods to be replaced with constructors; but I haven't
done this, as the series is already too long. Other 'deprecated'
methods can probably be handled the same way.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
This patch turns a grab bag of value functions to methods of value.
These are done together because their implementations are
interrelated.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
This turns value_from_xmethod, result_type_of_xmethod, and
call_xmethod to be methods of value. value_from_xmethod is a static
"constructor" now.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
This turns the remaining value_contents functions -- value_contents,
value_contents_all, value_contents_for_printing, and
value_contents_for_printing_const -- into methods of value. It also
converts the static functions require_not_optimized_out and
require_available to be private methods.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
This changes value_fetch_lazy to be a method of value. A few helper
functions are converted as well, to avoid problems in later patches
when the data members are all made private.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
This turns value_contents_raw, value_contents_writeable, and
value_contents_all_raw into methods on value. The remaining functions
will be changed later in the series; they were a bit trickier and so I
didn't include them in this patch.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
This changes the value_lazy and set_value_lazy functions to be methods
of value. Much of this patch was written by script.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
This changes various offset-related functions to be methods of value.
Much of this patch was written by script.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
This changes deprecated_set_value_type to be a method of value. Much
of this patch was written by script.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
PR c++/29503 points out that something like "b->Base::member" will
crash when 'b' does not have pointer type. This seems to be a simple
oversight in eval_op_member.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29503
Reviewed-By: Bruno Larsen <blarsen@redhat.com>
This commit is the result of running the gdb/copyright.py script,
which automated the update of the copyright year range for all
source files managed by the GDB project to be updated to include
year 2023.
This changes GDB to use frame_info_ptr instead of frame_info *
The substitution was done with multiple sequential `sed` commands:
sed 's/^struct frame_info;/class frame_info_ptr;/'
sed 's/struct frame_info \*/frame_info_ptr /g' - which left some
issues in a few files, that were manually fixed.
sed 's/\<frame_info \*/frame_info_ptr /g'
sed 's/frame_info_ptr $/frame_info_ptr/g' - used to remove whitespace
problems.
The changed files were then manually checked and some 'sed' changes
undone, some constructors and some gets were added, according to what
made sense, and what Tromey originally did
Co-Authored-By: Bruno Larsen <blarsen@redhat.com>
Approved-by: Tom Tomey <tom@tromey.com>
Add the `length` and `set_length` methods on `struct type`, in order to remove
the `TYPE_LENGTH` macro. In this patch, the macro is changed to use the
getter, so all the call sites of the macro that are used as a setter are
changed to use the setter method directly. The next patch will remove the
macro completely.
Change-Id: Id1090244f15c9856969b9be5006aefe8d8897ca4
This updates the Ada expression parser to implement context-sensitive
field name completion. This is PR ada/28727.
This is somewhat complicated due to some choices in the Ada lexer --
it chooses to represent a sequence of "."-separated identifiers as a
single token, so the parser must partially recreate the completer's
logic to find the completion word boundaries.
Despite the minor warts in this patch, though, it is a decent
improvement. It's possible that the DWARF reader rewrite will help
fix the package completion problem pointed out in this patch as well.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=28727
This refactors the gdb expression completion code to make it easier to
add more types of completers.
In the old approach, just two kinds of completers were supported:
field names for some sub-expression, or tag names (like "enum
something"). The data for each kind was combined in single structure,
"expr_completion_state", and handled explicitly by
complete_expression.
In the new approach, the parser state just holds an object that is
responsible for implementing completion. This way, new completion
types can be added by subclassing this base object.
The structop completer is moved into structop_base_operation, and new
objects are defined for use by the completion code. This moves much
of the logic of expression completion out of completer.c as well.
On x86 machines with xmm register, and with recent versions of
systemtap (and gcc?), it can occur that stap probe arguments will be
placed into xmm registers.
I notice this happening on a current Fedora Rawhide install with the
following package versions installed:
$ rpm -q glibc systemtap gcc
glibc-2.35.9000-10.fc37.x86_64
systemtap-4.7~pre16468670g9f253544-1.fc37.x86_64
gcc-12.0.1-0.12.fc37.x86_64
If I check the probe data in libc, I see this:
$ readelf -n /lib64/libc.so.6
...
stapsdt 0x0000004d NT_STAPSDT (SystemTap probe descriptors)
Provider: libc
Name: pthread_start
Location: 0x0000000000090ac3, Base: 0x00000000001c65c4, Semaphore: 0x0000000000000000
Arguments: 8@%xmm1 8@1600(%rbx) 8@1608(%rbx)
stapsdt 0x00000050 NT_STAPSDT (SystemTap probe descriptors)
Provider: libc
Name: pthread_create
Location: 0x00000000000912f1, Base: 0x00000000001c65c4, Semaphore: 0x0000000000000000
Arguments: 8@%xmm1 8@%r13 8@8(%rsp) 8@16(%rsp)
...
Notice that for both of these probes, the first argument is a uint64_t
stored in the xmm1 register.
Unfortunately, if I try to use this probe within GDB, then I can't
view the first argument. Here's an example session:
$ gdb $(which gdb)
(gdb) start
...
(gdb) info probes stap libc pthread_create
...
(gdb) break *0x00007ffff729e2f1 # Use address of probe.
(gdb) continue
...
(gdb) p $_probe_arg0
Invalid cast.
What's going wrong? If I re-run my session, but this time use 'set
debug stap-expression 1', this is what I see:
(gdb) set debug stap-expression 1
(gdb) p $_probe_arg0
Operation: UNOP_CAST
Operation: OP_REGISTER
String: xmm1
Type: uint64_t
Operation: UNOP_CAST
Operation: OP_REGISTER
String: r13
Type: uint64_t
Operation: UNOP_CAST
Operation: UNOP_IND
Operation: UNOP_CAST
Operation: BINOP_ADD
Operation: OP_LONG
Type: long
Constant: 0x0000000000000008
Operation: OP_REGISTER
String: rsp
Type: uint64_t *
Type: uint64_t
Operation: UNOP_CAST
Operation: UNOP_IND
Operation: UNOP_CAST
Operation: BINOP_ADD
Operation: OP_LONG
Type: long
Constant: 0x0000000000000010
Operation: OP_REGISTER
String: rsp
Type: uint64_t *
Type: uint64_t
Invalid cast.
(gdb)
The important bit is this:
Operation: UNOP_CAST
Operation: OP_REGISTER
String: xmm1
Type: uint64_t
Which is where we cast the xmm1 register to uint64_t. And the final
piece of the puzzle is:
(gdb) ptype $xmm1
type = union vec128 {
v8bf16 v8_bfloat16;
v4f v4_float;
v2d v2_double;
v16i8 v16_int8;
v8i16 v8_int16;
v4i32 v4_int32;
v2i64 v2_int64;
uint128_t uint128;
}
So, we are attempting to cast a union type to a scalar type, which is
not supporting in C/C++, and as a consequence GDB's expression
evaluator throws an error when we attempt to do this.
The first approach I considered for solving this problem was to try
and make use of gdbarch_stap_adjust_register. We already have a
gdbarch method (gdbarch_stap_adjust_register) that allows us to tweak
the name of the register that we access. Currently only x86
architectures use this to transform things like ax to eax in some
cases.
I wondered, what if we change gdbarch_stap_adjust_register to do more
than just change the register names? What if this method instead
became gdbarch_stap_read_register. This new method would return a
operation_up, and would take the register name, and the type we are
trying to read from the register, and return the operation that
actually reads the register.
The default implementation of this method would just use
user_reg_map_name_to_regnum, and then create a register_operation,
like we already do in stap_parse_register_operand. But, for x86
architectures this method would fist possibly adjust the register
name, then do the default action to read the register. Finally, for
x86 this method would spot when we were accessing an xmm register,
and, based on the type being pulled from the register, would extract
the correct field from the union.
The benefit of this approach is that it would work with the expression
types that GDB currently supports. The draw back would be that this
approach would not be very generic. We'd need code to handle each
sub-field size with an xmm register. If other architectures started
using vector registers for probe arguments, those architectures would
have to create their own gdbarch_stap_read_register method. And
finally, the type of the xmm registers comes from the type defined in
the target description, there's a risk that GDB might end up
hard-coding the names of type sub-fields, then if a target uses a
different target description, with different field names for xmm
registers, the stap probes would stop working.
And so, based on all the above draw backs, I rejected this first
approach.
My second plan involves adding a new expression type to GDB called
unop_extract_operation. This new expression takes a value and a type,
during evaluation the value contents are fetched, and then a new value
is extracted from the value contents (based on type). This is similar
to the following C expression:
result_value = *((output_type *) &input_value);
Obviously we can't actually build this expression in this case, as the
input_value is in a register, but hopefully the above makes it clearer
what I'm trying to do.
The benefit of the new expression approach is that this code can be
shared across all architectures, and it doesn't care about sub-field
names within the union type.
The draw-backs that I see are potential future problems if arguments
are not stored within the least significant bytes of the register.
However if/when that becomes an issue we can adapt the
gdbarch_stap_read_register approach to allow architectures to control
how a value is extracted.
For testing, I've extended the existing gdb.base/stap-probe.exp test
to include a function that tries to force an argument into an xmm
register. Obviously, that will only work on a x86 target, so I've
guarded the new function with an appropriate GCC define. In the exp
script we use readelf to check if the probe exists, and is using the
xmm register.
If the probe doesn't exist then the associated tests are skipped.
If the probe exists, put isn't using the xmm register (which will
depend on systemtap/gcc versions), then again, the tests are skipped.
Otherwise, we can run the test. I think the cost of running readelf
is pretty low, so I don't feel too bad making all the non-xmm targets
running this step.
I found that on a Fedora 35 install, with these packages installed, I
was able to run this test and have the probe argument be placed in an
xmm register:
$ rpm -q systemtap gcc glibc
systemtap-4.6-4.fc35.x86_64
gcc-11.2.1-9.fc35.x86_64
glibc-2.34-7.fc35.x86_64
Finally, as this patch adds a new operation type, then I need to
consider how to generate an agent expression for the new operation
type.
I have kicked the can down the road a bit on this. In the function
stap_parse_register_operand, I only create a unop_extract_operation in
the case where the register type is non-scalar, this means that in
most cases I don't need to worry about generating an agent expression
at all.
In the xmm register case, when an unop_extract_operation will be
created, I have sketched out how the agent expression could be
handled, however, this code is currently not reached. When we try to
generate the agent expression to place the xmm register on the stack,
GDB hits this error:
(gdb) trace -probe-stap test:xmmreg
Tracepoint 1 at 0x401166
(gdb) actions
Enter actions for tracepoint 1, one per line.
End with a line saying just "end".
>collect $_probe_arg0
Value not scalar: cannot be an rvalue.
This is because GDB doesn't currently support placing non-scalar types
on the agent expression evaluation stack. Solving this is clearly
related to the original problem, but feels a bit like a second
problem. I'd like to get feedback on whether my approach to solving
the original problem is acceptable or not before I start looking at
how to handle xmm registers within agent expressions.
eval_op_concat has code to search for an operator overload of
BINOP_CONCAT. However, the operator overloading code is specific to
C++, which does not have this operator. And,
binop_types_user_defined_p rejects this case right at the start, and
value_x_binop does not handle this case. I think this code has been
dead for a very long time. This patch removes it and hoists the
remaining call into concatenation::evaluate, removing eval_op_concat
entirely.
eval_op_string is only used in a single place -- the implementation of
string_operation. This patch turns it into the
string_operation::evaluate method, removing a bit of extraneous code.
Add a getter and a setter for a symbol's type. Remove the corresponding
macro and adjust all callers.
Change-Id: Ie1a137744c5bfe1df4d4f9ae5541c5299577c8de
