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26f53cd385
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.
222 lines
7.1 KiB
C++
222 lines
7.1 KiB
C++
/* Definitions for expressions stored in reversed prefix form, for GDB.
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Copyright (C) 1986-2021 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#if !defined (EXPRESSION_H)
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#define EXPRESSION_H 1
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#include "gdbtypes.h"
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/* While parsing expressions we need to track the innermost lexical block
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that we encounter. In some situations we need to track the innermost
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block just for symbols, and in other situations we want to track the
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innermost block for symbols and registers. These flags are used by the
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innermost block tracker to control which blocks we consider for the
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innermost block. These flags can be combined together as needed. */
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enum innermost_block_tracker_type
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{
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/* Track the innermost block for symbols within an expression. */
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INNERMOST_BLOCK_FOR_SYMBOLS = (1 << 0),
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/* Track the innermost block for registers within an expression. */
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INNERMOST_BLOCK_FOR_REGISTERS = (1 << 1)
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};
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DEF_ENUM_FLAGS_TYPE (enum innermost_block_tracker_type,
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innermost_block_tracker_types);
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/* Definitions for saved C expressions. */
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/* An expression is represented as a vector of union exp_element's.
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Each exp_element is an opcode, except that some opcodes cause
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the following exp_element to be treated as a long or double constant
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or as a variable. The opcodes are obeyed, using a stack for temporaries.
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The value is left on the temporary stack at the end. */
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/* When it is necessary to include a string,
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it can occupy as many exp_elements as it needs.
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We find the length of the string using strlen,
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divide to find out how many exp_elements are used up,
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and skip that many. Strings, like numbers, are indicated
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by the preceding opcode. */
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enum exp_opcode : uint8_t
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{
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#define OP(name) name ,
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#include "std-operator.def"
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#undef OP
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/* Existing only to swallow the last comma (',') from last .inc file. */
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OP_UNUSED_LAST
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};
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/* Values of NOSIDE argument to eval_subexp. */
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enum noside
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{
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EVAL_NORMAL,
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EVAL_SKIP, /* Only effect is to increment pos.
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Return type information where
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possible. */
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EVAL_AVOID_SIDE_EFFECTS /* Don't modify any variables or
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call any functions. The value
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returned will have the correct
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type, and will have an
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approximately correct lvalue
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type (inaccuracy: anything that is
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listed as being in a register in
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the function in which it was
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declared will be lval_register).
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Ideally this would not even read
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target memory, but currently it
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does in many situations. */
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};
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union exp_element
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{
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enum exp_opcode opcode;
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struct symbol *symbol;
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struct minimal_symbol *msymbol;
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LONGEST longconst;
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gdb_byte floatconst[16];
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/* Really sizeof (union exp_element) characters (or less for the last
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element of a string). */
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char string;
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struct type *type;
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struct internalvar *internalvar;
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const struct block *block;
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struct objfile *objfile;
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};
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struct expression
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{
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expression (const struct language_defn *, struct gdbarch *, size_t);
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~expression ();
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DISABLE_COPY_AND_ASSIGN (expression);
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void resize (size_t);
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/* Return the opcode for the outermost sub-expression of this
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expression. */
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enum exp_opcode first_opcode () const
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{
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return elts[0].opcode;
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}
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/* Evaluate the expression. EXPECT_TYPE is the context type of the
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expression; normally this should be nullptr. NOSIDE controls how
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evaluation is performed. */
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struct value *evaluate (struct type *expect_type, enum noside noside);
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/* Language it was entered in. */
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const struct language_defn *language_defn;
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/* Architecture it was parsed in. */
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struct gdbarch *gdbarch;
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int nelts = 0;
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union exp_element *elts;
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};
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typedef std::unique_ptr<expression> expression_up;
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/* Macros for converting between number of expression elements and bytes
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to store that many expression elements. */
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#define EXP_ELEM_TO_BYTES(elements) \
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((elements) * sizeof (union exp_element))
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#define BYTES_TO_EXP_ELEM(bytes) \
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(((bytes) + sizeof (union exp_element) - 1) / sizeof (union exp_element))
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/* From parse.c */
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class innermost_block_tracker;
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extern expression_up parse_expression (const char *,
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innermost_block_tracker * = nullptr,
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bool void_context_p = false);
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extern expression_up parse_expression_with_language (const char *string,
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enum language lang);
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extern struct type *parse_expression_for_completion
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(const char *, gdb::unique_xmalloc_ptr<char> *, enum type_code *);
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class innermost_block_tracker;
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extern expression_up parse_exp_1 (const char **, CORE_ADDR pc,
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const struct block *, int,
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innermost_block_tracker * = nullptr);
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/* From eval.c */
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extern struct value *evaluate_subexp_standard
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(struct type *, struct expression *, int *, enum noside);
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/* Evaluate a function call. The function to be called is in CALLEE and
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the arguments passed to the function are in ARGVEC.
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FUNCTION_NAME is the name of the function, if known.
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DEFAULT_RETURN_TYPE is used as the function's return type if the return
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type is unknown. */
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extern struct value *evaluate_subexp_do_call (expression *exp,
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enum noside noside,
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value *callee,
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gdb::array_view<value *> argvec,
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const char *function_name,
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type *default_return_type);
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/* From expprint.c */
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extern void print_expression (struct expression *, struct ui_file *);
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extern const char *op_name (enum exp_opcode opcode);
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extern const char *op_string (enum exp_opcode);
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extern void dump_raw_expression (struct expression *,
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struct ui_file *, const char *);
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extern void dump_prefix_expression (struct expression *, struct ui_file *);
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/* In an OP_RANGE expression, either bound could be empty, indicating
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that its value is by default that of the corresponding bound of the
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array or string. Also, the upper end of the range can be exclusive
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or inclusive. So we have six sorts of subrange. This enumeration
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type is to identify this. */
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enum range_flag : unsigned
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{
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/* This is a standard range. Both the lower and upper bounds are
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defined, and the bounds are inclusive. */
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RANGE_STANDARD = 0,
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/* The low bound was not given. */
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RANGE_LOW_BOUND_DEFAULT = 1 << 0,
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/* The high bound was not given. */
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RANGE_HIGH_BOUND_DEFAULT = 1 << 1,
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/* The high bound of this range is exclusive. */
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RANGE_HIGH_BOUND_EXCLUSIVE = 1 << 2,
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/* The range has a stride. */
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RANGE_HAS_STRIDE = 1 << 3,
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};
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DEF_ENUM_FLAGS_TYPE (enum range_flag, range_flags);
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#endif /* !defined (EXPRESSION_H) */
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