This patch introduces class operation, the new base class for all
expression operations.
In the new approach, an operation is simply a class that presents a
certain interface. Operations own their operands, and management is
done via unique_ptr.
The operation interface is largely ad hoc, based on the evolution of
expression handling in GDB. Parts (for example,
evaluate_with_coercion) are probably redundant; however I took this
approach to try to avoid mixing different kinds of refactorings.
In some specific situations, rather than add a generic method across
the entire operation class hierarchy, I chose instead to use
dynamic_cast and specialized methods on certain concrete subclasses.
This will appear in some subsequent patches.
One goal of this work is to avoid the kinds of easy-to-make errors
that affected the old implementation. To this end, some helper
subclasses are also added here. These helpers automate the
implementation of the 'dump', 'uses_objfile', and 'constant_p'
methods. Nearly every concrete operation that is subsequently added
will use these facilities. (Note that the 'dump' implementation is
only outlined here, the body appears in the next patch.)
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* expression.h (expr::operation): New class.
(expr::make_operation): New function.
(expr::operation_up): New typedef.
* expop.h: New file.
* eval.c (operation::evaluate_for_cast)
(operation::evaluate_for_address, operation::evaluate_for_sizeof):
New methods.
* ax-gdb.c (operation::generate_ax): New method.
This splits MULTI_SUBSCRIPT into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_multi_subscript): New function.
(evaluate_subexp_standard): Use it.
This splits OP_OBJC_MSGCALL into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_objc_msgcall): New function.
(evaluate_subexp_standard): Use it.
This splits BINOP_ASSIGN_MODIFY into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_binop_assign_modify): New function.
(evaluate_subexp_standard): Use it.
This splits a couple of address-of and sizeof functions, so that the
body can be reused by the (coming) new expression code.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (evaluate_subexp_for_address_base): New function.
(evaluate_subexp_for_address): Use it.
(evaluate_subexp_for_sizeof_base): New function.
(evaluate_subexp_for_sizeof): Use it.
This splits OP_TYPE into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_type): New function.
(evaluate_subexp_standard): Use it.
This splits UNOP_POSTDECREMENT into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_postdec): New function.
(evaluate_subexp_standard): Use it.
This splits UNOP_POSTINCREMENT into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_postinc): New function.
(evaluate_subexp_standard): Use it.
This splits UNOP_PREDECREMENT into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_predec): New file.
(evaluate_subexp_standard): Use it.
This splits UNOP_PREINCREMENT into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_preinc): New function.
(evaluate_subexp_standard): Use it.
This splits UNOP_MEMVAL into a new function for future use. This new
function is also used to hande UNOP_MEMVAL_TYPE.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_memval): New function.
(evaluate_subexp_standard): Use it.
This splits UNOP_ALIGNOF into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_alignof): New function.
(evaluate_subexp_standard): Use it.
This splits UNOP_IND into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_ind): New function.
(evaluate_subexp_standard): Use it.
This splits UNOP_LOGICAL_NOT into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_lognot): New function.
(evaluate_subexp_standard): Use it.
This splits UNOP_COMPLEMENT into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_complement): New function.
(evaluate_subexp_standard): Use it.
This splits UNOP NEG into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_neg): New function.
(evaluate_subexp_standard): Use it.
This splits UNOP_PLUS into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_plus): New function.
(evaluate_subexp_standard): Use it.
This splits BINOP_REPEAT into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_repeat): New function.
(evaluate_subexp_standard): Use it.
This splits BINOP_LEQ into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_leq): New function.
(evaluate_subexp_standard): Use it.
This splits BINOP_GEQ into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_geq): New function.
(evaluate_subexp_standard): Use it.
This splits BINOP_GTR into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_gtr): New function.
(evaluate_subexp_standard): Use it.
This splits BINOP_LESS into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_less): New function.
(evaluate_subexp_standard): Use it.
This splits BINOP_NOTEQUAL into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_notequal): New function.
(evaluate_subexp_standard): Use it.
This splits BINOP_EQUAL into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_equal): New function.
(evaluate_subexp_standard): Use it.
This splits BINOP_SUBSCRIPT into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_subscript): New function.
(evaluate_subexp_standard): Use it.
This splits out a new eval_op_binary helper function. This function
can handle several different binary operations:
case BINOP_EXP:
case BINOP_MUL:
case BINOP_DIV:
case BINOP_INTDIV:
case BINOP_REM:
case BINOP_MOD:
case BINOP_LSH:
case BINOP_RSH:
case BINOP_BITWISE_AND:
case BINOP_BITWISE_IOR:
case BINOP_BITWISE_XOR:
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_binary): New function.
(evaluate_subexp_standard): Use it.
This splits BINOP_SUB into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_sub): New function.
(evaluate_subexp_standard): Use it.
This splits BINOP_ADD into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_add): New function.
(evaluate_subexp_standard): Use it.
This splits STRUCTOP_MEMBER into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_member): New function.
(evaluate_subexp_standard): Use it.
This splits STRUCTOP_PTR into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_structop_ptr): New function.
(evaluate_subexp_standard): Use it.
This splits STRUCTOP_STRUCT into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_structop_struct): New function.
(evaluate_subexp_standard): Use it.
This splits TERNOP_SLICE into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_ternop): New function.
(evaluate_subexp_standard): Use it.
This splits BINOP_CONCAT into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_concat): New function.
(evaluate_subexp_standard): Use it.
This splits OP_OBJC_SELECTOR into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_objc_selector): New function.
(evaluate_subexp_standard): Use it.
This splits OP_STRING into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_string): New function.
(evaluate_subexp_standard): Use it.
This splits OP_REGISTER into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_register): New function.
(evaluate_subexp_standard): Use it.
This splits OP_FUNC_STATIC_VAR into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_func_static_var): New function.
(evaluate_subexp_standard): Use it.
This splits OP_VAR_MSYM_VALUE into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_var_msym_value): New function.
(evaluate_subexp_standard): Use it.
This splits OP_VAR_ENTRY_VALUE into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_var_entry_value): New function.
(evaluate_subexp_standard): Use it.
This splits OP_SCOPE into a new function for future use.
gdb/ChangeLog
2021-03-08 Tom Tromey <tom@tromey.com>
* eval.c (eval_op_scope): New function.
(evaluate_subexp_standard): Use it.
When evaluating and expression containing UNOP_IND in mode
EVAL_AVOID_SIDE_EFFECTS, GDB currently (mostly) returns the result of
a call to value_zero meaning we get back an object with the correct
type, but its contents are all zero.
If the target type contains fields with dynamic type then in order to
resolve these dynamic fields GDB will need to read the value of the
field from within the parent object. In this case the field value
will be zero as a result of the call to value_zero mentioned above.
The idea behind EVAL_AVOID_SIDE_EFFECTS is to avoid the chance that
doing something like `ptype` will modify state within the target, for
example consider: ptype i++.
However, there is already precedence within GDB that sometimes, in
order to get accurate type results, we can't avoid reading from the
target, even when EVAL_AVOID_SIDE_EFFECTS is in effect. For example I
would point to eval.c:evaluate_var_value, the handling of OP_REGISTER,
the handling of value_x_unop in many places. I believe the Ada
expression evaluator also ignore EVAL_AVOID_SIDE_EFFECTS in some
cases.
I am therefor proposing that, in the case where a pointer points at a
dynamic type, we allow UNOP_IND to perform the actual indirection.
This allows accurate types to be displayed in more cases.
gdb/ChangeLog:
* eval.c (evaluate_subexp_standard): Call value_ind for points to
dynamic types in UNOP_IND.
gdb/testsuite/ChangeLog:
* gdb.fortran/pointer-to-pointer.exp: Additional tests.
This introduces a new method, expression::evaluate, and changes the
top-level expression-evaluation functions to use it. Stack temporary
handling is moved into this new method, which makes sense because that
handling was only done when "*pos == 0".
This patch avoids some temporary regressions related to stack
temporary in the larger expression rewrite series. I've pulled it out
separately because it seems like a reasonable change in its own right,
and because it's better to avoid making that series even longer.
Regression tested on x86-64 Fedora 32.
gdb/ChangeLog
2021-02-18 Tom Tromey <tom@tromey.com>
* expression.h (struct expression) <evaluate>: Declare method.
* eval.c (evaluate_subexp): Simplify.
(expression::evaluate): New method.
(evaluate_expression, evaluate_type): Use expression::evaluate.
This commits the result of running gdb/copyright.py as per our Start
of New Year procedure...
gdb/ChangeLog
Update copyright year range in copyright header of all GDB files.
The MULTI_SUBSCRIPT code in evaluate_subexp_standard has a comment
saying that perhaps the EVAL_SKIP handling is incorrect. This patch
simplifies this code. In particular, it precomputes all the indices
in a separate loop and removes some complicated flow-control.
Tested using the gdb.modula2 and gdb.dlang test suites, as these are
the only parsers that emit MULTI_SUBSCRIPT.
gdb/ChangeLog
2020-12-27 Tom Tromey <tom@tromey.com>
* eval.c (evaluate_subexp_standard) <case MULTI_SUBSCRIPT>:
Simplify.
In PR gdb/27059 an issue was discovered where GDB would sometimes
trigger undefined behaviour in the form of signed integer overflow.
The problem here is that GDB was reading random garbage from the
inferior memory space, assuming this data was valid, and performing
arithmetic on it.
This bug raises an interesting general problem with GDB's DWARF
expression evaluator, which is this:
We currently assume that the DWARF expressions being evaluated are
well formed, and well behaving. As an example, this is the expression
that the bug was running into problems on, this was used as the
expression for a DW_AT_byte_stride of a DW_TAG_subrange_type:
DW_OP_push_object_address;
DW_OP_plus_uconst: 88;
DW_OP_deref;
DW_OP_push_object_address;
DW_OP_plus_uconst: 32;
DW_OP_deref;
DW_OP_mul
Two values are read from the inferior and multiplied together. GDB
should not assume that any value read from the inferior is in any way
sane, as such the implementation of DW_OP_mul should be guarding
against overflow and doing something semi-sane here.
However, it turns out that the original bug PR gdb/27059, is hitting a
more specific case, which doesn't require changes to the DWARF
expression evaluator, so I'm going to leave the above issue for
another day.
In the test mentioned in the bug GDB is actually trying to resolve the
dynamic type of a Fortran array that is NOT allocated. A
non-allocated Fortran array is one that does not have any data
allocated for it yet, and even the upper and lower bounds of the array
are not yet known.
It turns out that, at least for gfortran compiled code, the data
fields that describe the byte-stride are not initialised until the
array is allocated.
This leads me to the following conclusion: GDB should not try to
resolve the bounds, or stride information for an array that is not
allocated (or not associated, a similar, but slightly different
Fortran feature). Instead, each of these properties should be set to
undefined if the array is not allocated (or associated).
That is what this commit does. There's a new flag that is passed
around during the dynamic array resolution. When this flag is true
the dynamic properties are resolved using the DWARF expressions as
they currently are, but when this flag is false the expressions are
not evaluated, and instead the properties are set to undefined.
gdb/ChangeLog:
PR gdb/27059
* eval.c (evaluate_subexp_for_sizeof): Handle not allocated and
not associated arrays.
* f-lang.c (fortran_adjust_dynamic_array_base_address_hack): Don't
adjust arrays that are not allocated/associated.
* gdbtypes.c (resolve_dynamic_range): Update header comment. Add
new parameter which is used to sometimes set dynamic properties to
undefined.
(resolve_dynamic_array_or_string): Update header comment. Add new
parameter which is used to guard evaluating dynamic properties.
Resolve allocated/associated properties first.
gdb/testsuite/ChangeLog:
PR gdb/27059
* gdb.dwarf2/dyn-type-unallocated.c: New file.
* gdb.dwarf2/dyn-type-unallocated.exp: New file.
While working on the expression rewrite, I found a few spots that
called the internal functions of the expression evaluator, just to
pass in an expected type. This patch adds a parameter to
evaluate_expression so that these functions can avoid this dependency.
Regression tested on x86-64 Fedora 28.
gdb/ChangeLog
2020-12-15 Tom Tromey <tom@tromey.com>
* stap-probe.c (stap_probe::evaluate_argument): Use
evaluate_expression.
* dtrace-probe.c (dtrace_probe::evaluate_argument): Use
evaluate_expression.
* value.h (evaluate_expression): Add expect_type parameter.
* objc-lang.c (print_object_command): Call evaluate_expression.
* eval.c (evaluate_expression): Add expect_type parameter.
This adds a new helper method, expression::first_opcode, that extracts
the outermost opcode of an expression. This simplifies some patches
in the expression rewrite series.
Note that this patch requires the earlier patch to avoid manual
dissection of OP_TYPE operations.
2020-12-15 Tom Tromey <tom@tromey.com>
* varobj.c (varobj_create): Use first_opcode.
* value.c (init_if_undefined_command): Use first_opcode.
* typeprint.c (whatis_exp): Use first_opcode.
* tracepoint.c (validate_actionline): Use first_opcode.
(encode_actions_1): Use first_opcode.
* stack.c (return_command): Use first_opcode.
* expression.h (struct expression) <first_opcode>: New method.
* eval.c (parse_and_eval_type): Use first_opcode.
* dtrace-probe.c (dtrace_process_dof_probe): Use first_opcode.
I noticed hat evaluate_subexp_do_call takes an array of arguments and
a count -- but, unlike the usual convention, the count does not
include the first element.
This patch changes this function to match call_function_by_hand --
passing the callee separately, and using an array_view for the
arguments. This makes it simpler to understand.
Regression tested on x86-64 Fedora 28.
gdb/ChangeLog
2020-12-15 Tom Tromey <tom@tromey.com>
* f-lang.c (evaluate_subexp_f): Update.
* expression.h (evaluate_subexp_do_call): Update.
* eval.c (evaluate_subexp_do_call): Add callee parameter. Replace
nargs, argvec with array_view.
(evaluate_funcall): Update.
I noticed that the argumen to parse_and_eval_type could be "const".
This patch implements this change.
I wonder if this could be removed. It's only called via
check_stub_method_group, which seems questionable to me. However, I
didn't look into doing this.
gdb/ChangeLog
2020-12-13 Tom Tromey <tom@tromey.com>
* gdbtypes.c (safe_parse_type): Make argument const.
* value.h (parse_and_eval_type): Make argument const.
* eval.c (parse_and_eval_type): Make argument const.
get_discrete_bounds currently has three possible return values (see its
current doc for details). It appears that for all callers, it would be
sufficient to have a boolean "worked" / "didn't work" return value.
Change the return type of get_discrete_bounds to bool and adjust all
callers. Doing so simplifies the following patch.
gdb/ChangeLog:
* gdbtypes.h (get_discrete_bounds): Return bool, adjust all
callers.
* gdbtypes.c (get_discrete_bounds): Return bool.
Change-Id: Ie51feee23c75f0cd7939742604282d745db59172
