/* Definitions for expressions stored in reversed prefix form, for GDB.
- Copyright (C) 1986, 1989, 1992, 1994, 2000, 2003, 2005, 2007, 2008
- Free Software Foundation, Inc.
+ Copyright (C) 1986-2021 Free Software Foundation, Inc.
This file is part of GDB.
#if !defined (EXPRESSION_H)
#define EXPRESSION_H 1
+#include "gdbtypes.h"
-#include "symtab.h" /* Needed for "struct block" type. */
-#include "doublest.h" /* Needed for DOUBLEST. */
+/* While parsing expressions we need to track the innermost lexical block
+ that we encounter. In some situations we need to track the innermost
+ block just for symbols, and in other situations we want to track the
+ innermost block for symbols and registers. These flags are used by the
+ innermost block tracker to control which blocks we consider for the
+ innermost block. These flags can be combined together as needed. */
+enum innermost_block_tracker_type
+{
+ /* Track the innermost block for symbols within an expression. */
+ INNERMOST_BLOCK_FOR_SYMBOLS = (1 << 0),
-/* Definitions for saved C expressions. */
+ /* Track the innermost block for registers within an expression. */
+ INNERMOST_BLOCK_FOR_REGISTERS = (1 << 1)
+};
+DEF_ENUM_FLAGS_TYPE (enum innermost_block_tracker_type,
+ innermost_block_tracker_types);
-/* An expression is represented as a vector of union exp_element's.
- Each exp_element is an opcode, except that some opcodes cause
- the following exp_element to be treated as a long or double constant
- or as a variable. The opcodes are obeyed, using a stack for temporaries.
- The value is left on the temporary stack at the end. */
+enum exp_opcode : uint8_t
+ {
+#define OP(name) name ,
-/* When it is necessary to include a string,
- it can occupy as many exp_elements as it needs.
- We find the length of the string using strlen,
- divide to find out how many exp_elements are used up,
- and skip that many. Strings, like numbers, are indicated
- by the preceding opcode. */
+#include "std-operator.def"
-enum exp_opcode
- {
- /* Used when it's necessary to pass an opcode which will be ignored,
- or to catch uninitialized values. */
- OP_NULL,
-
-/* BINOP_... operate on two values computed by following subexpressions,
- replacing them by one result value. They take no immediate arguments. */
-
- BINOP_ADD, /* + */
- BINOP_SUB, /* - */
- BINOP_MUL, /* * */
- BINOP_DIV, /* / */
- BINOP_REM, /* % */
- BINOP_MOD, /* mod (Knuth 1.2.4) */
- BINOP_LSH, /* << */
- BINOP_RSH, /* >> */
- BINOP_LOGICAL_AND, /* && */
- BINOP_LOGICAL_OR, /* || */
- BINOP_BITWISE_AND, /* & */
- BINOP_BITWISE_IOR, /* | */
- BINOP_BITWISE_XOR, /* ^ */
- BINOP_EQUAL, /* == */
- BINOP_NOTEQUAL, /* != */
- BINOP_LESS, /* < */
- BINOP_GTR, /* > */
- BINOP_LEQ, /* <= */
- BINOP_GEQ, /* >= */
- BINOP_REPEAT, /* @ */
- BINOP_ASSIGN, /* = */
- BINOP_COMMA, /* , */
- BINOP_SUBSCRIPT, /* x[y] */
- BINOP_EXP, /* Exponentiation */
-
- /* C++. */
-
- BINOP_MIN, /* <? */
- BINOP_MAX, /* >? */
-
- /* STRUCTOP_MEMBER is used for pointer-to-member constructs.
- X . * Y translates into X STRUCTOP_MEMBER Y. */
- STRUCTOP_MEMBER,
-
- /* STRUCTOP_MPTR is used for pointer-to-member constructs
- when X is a pointer instead of an aggregate. */
- STRUCTOP_MPTR,
-
- /* end of C++. */
-
- /* For Modula-2 integer division DIV */
- BINOP_INTDIV,
-
- BINOP_ASSIGN_MODIFY, /* +=, -=, *=, and so on.
- The following exp_element is another opcode,
- a BINOP_, saying how to modify.
- Then comes another BINOP_ASSIGN_MODIFY,
- making three exp_elements in total. */
-
- /* Modula-2 standard (binary) procedures */
- BINOP_VAL,
- BINOP_INCL,
- BINOP_EXCL,
-
- /* Concatenate two operands, such as character strings or bitstrings.
- If the first operand is a integer expression, then it means concatenate
- the second operand with itself that many times. */
- BINOP_CONCAT,
-
- /* For (the deleted) Chill and Pascal. */
- BINOP_IN, /* Returns 1 iff ARG1 IN ARG2. */
-
- /* This is the "colon operator" used various places in (the
- deleted) Chill. */
- BINOP_RANGE,
-
- /* This must be the highest BINOP_ value, for expprint.c. */
- BINOP_END,
-
- /* Operates on three values computed by following subexpressions. */
- TERNOP_COND, /* ?: */
-
- /* A sub-string/sub-array. (the deleted) Chill syntax:
- OP1(OP2:OP3). Return elements OP2 through OP3 of OP1. */
- TERNOP_SLICE,
-
- /* A sub-string/sub-array. (The deleted) Chill syntax: OP1(OP2 UP
- OP3). Return OP3 elements of OP1, starting with element
- OP2. */
- TERNOP_SLICE_COUNT,
-
- /* Multidimensional subscript operator, such as Modula-2 x[a,b,...].
- The dimensionality is encoded in the operator, like the number of
- function arguments in OP_FUNCALL, I.E. <OP><dimension><OP>.
- The value of the first following subexpression is subscripted
- by each of the next following subexpressions, one per dimension. */
- MULTI_SUBSCRIPT,
-
- /* The OP_... series take immediate following arguments.
- After the arguments come another OP_... (the same one)
- so that the grouping can be recognized from the end. */
-
- /* OP_LONG is followed by a type pointer in the next exp_element
- and the long constant value in the following exp_element.
- Then comes another OP_LONG.
- Thus, the operation occupies four exp_elements. */
- OP_LONG,
-
- /* OP_DOUBLE is similar but takes a DOUBLEST constant instead of a long. */
- OP_DOUBLE,
-
- /* OP_VAR_VALUE takes one struct block * in the following element,
- and one struct symbol * in the following exp_element, followed by
- another OP_VAR_VALUE, making four exp_elements. If the block is
- non-NULL, evaluate the symbol relative to the innermost frame
- executing in that block; if the block is NULL use the selected frame. */
- OP_VAR_VALUE,
-
- /* OP_LAST is followed by an integer in the next exp_element.
- The integer is zero for the last value printed,
- or it is the absolute number of a history element.
- With another OP_LAST at the end, this makes three exp_elements. */
- OP_LAST,
-
- /* OP_REGISTER is followed by a string in the next exp_element.
- This is the name of a register to fetch. */
- OP_REGISTER,
-
- /* OP_INTERNALVAR is followed by an internalvar ptr in the next exp_element.
- With another OP_INTERNALVAR at the end, this makes three exp_elements. */
- OP_INTERNALVAR,
-
- /* OP_FUNCALL is followed by an integer in the next exp_element.
- The integer is the number of args to the function call.
- That many plus one values from following subexpressions
- are used, the first one being the function.
- The integer is followed by a repeat of OP_FUNCALL,
- making three exp_elements. */
- OP_FUNCALL,
-
- /* OP_OBJC_MSGCALL is followed by a string in the next exp_element and then an
- integer. The string is the selector string. The integer is the number
- of arguments to the message call. That many plus one values are used,
- the first one being the object pointer. This is an Objective C message */
- OP_OBJC_MSGCALL,
-
- /* This is EXACTLY like OP_FUNCALL but is semantically different.
- In F77, array subscript expressions, substring expressions
- and function calls are all exactly the same syntactically. They may
- only be disambiguated at runtime. Thus this operator, which
- indicates that we have found something of the form <name> ( <stuff> ) */
- OP_F77_UNDETERMINED_ARGLIST,
-
- /* The following OP is a special one, it introduces a F77 complex
- literal. It is followed by exactly two args that are doubles. */
- OP_COMPLEX,
-
- /* OP_STRING represents a string constant.
- Its format is the same as that of a STRUCTOP, but the string
- data is just made into a string constant when the operation
- is executed. */
- OP_STRING,
-
- /* OP_BITSTRING represents a packed bitstring constant.
- Its format is the same as that of a STRUCTOP, but the bitstring
- data is just made into a bitstring constant when the operation
- is executed. */
- OP_BITSTRING,
-
- /* OP_ARRAY creates an array constant out of the following subexpressions.
- It is followed by two exp_elements, the first containing an integer
- that is the lower bound of the array and the second containing another
- integer that is the upper bound of the array. The second integer is
- followed by a repeat of OP_ARRAY, making four exp_elements total.
- The bounds are used to compute the number of following subexpressions
- to consume, as well as setting the bounds in the created array constant.
- The type of the elements is taken from the type of the first subexp,
- and they must all match. */
- OP_ARRAY,
-
- /* UNOP_CAST is followed by a type pointer in the next exp_element.
- With another UNOP_CAST at the end, this makes three exp_elements.
- It casts the value of the following subexpression. */
- UNOP_CAST,
-
- /* UNOP_MEMVAL is followed by a type pointer in the next exp_element
- With another UNOP_MEMVAL at the end, this makes three exp_elements.
- It casts the contents of the word addressed by the value of the
- following subexpression. */
- UNOP_MEMVAL,
-
- /* UNOP_MEMVAL_TLS is followed by a `struct objfile' pointer in the next
- exp_element and a type pointer in the following exp_element.
- With another UNOP_MEMVAL_TLS at the end, this makes four exp_elements.
- It casts the contents of the word offsetted by the value of the
- following subexpression from the TLS specified by `struct objfile'. */
- UNOP_MEMVAL_TLS,
-
- /* UNOP_... operate on one value from a following subexpression
- and replace it with a result. They take no immediate arguments. */
-
- UNOP_NEG, /* Unary - */
- UNOP_LOGICAL_NOT, /* Unary ! */
- UNOP_COMPLEMENT, /* Unary ~ */
- UNOP_IND, /* Unary * */
- UNOP_ADDR, /* Unary & */
- UNOP_PREINCREMENT, /* ++ before an expression */
- UNOP_POSTINCREMENT, /* ++ after an expression */
- UNOP_PREDECREMENT, /* -- before an expression */
- UNOP_POSTDECREMENT, /* -- after an expression */
- UNOP_SIZEOF, /* Unary sizeof (followed by expression) */
-
- UNOP_PLUS, /* Unary plus */
-
- UNOP_CAP, /* Modula-2 standard (unary) procedures */
- UNOP_CHR,
- UNOP_ORD,
- UNOP_ABS,
- UNOP_FLOAT,
- UNOP_HIGH,
- UNOP_MAX,
- UNOP_MIN,
- UNOP_ODD,
- UNOP_TRUNC,
-
- /* (The deleted) Chill builtin functions. */
- UNOP_LOWER, UNOP_UPPER, UNOP_LENGTH, UNOP_CARD, UNOP_CHMAX, UNOP_CHMIN,
-
- OP_BOOL, /* Modula-2 builtin BOOLEAN type */
- OP_M2_STRING, /* Modula-2 string constants */
-
- /* STRUCTOP_... operate on a value from a following subexpression
- by extracting a structure component specified by a string
- that appears in the following exp_elements (as many as needed).
- STRUCTOP_STRUCT is used for "." and STRUCTOP_PTR for "->".
- They differ only in the error message given in case the value is
- not suitable or the structure component specified is not found.
-
- The length of the string follows the opcode, followed by
- BYTES_TO_EXP_ELEM(length) elements containing the data of the
- string, followed by the length again and the opcode again. */
-
- STRUCTOP_STRUCT,
- STRUCTOP_PTR,
-
- /* C++: OP_THIS is just a placeholder for the class instance variable.
- It just comes in a tight (OP_THIS, OP_THIS) pair. */
- OP_THIS,
-
- /* Objective-C: OP_OBJC_SELF is just a placeholder for the class instance
- variable. It just comes in a tight (OP_OBJC_SELF, OP_OBJC_SELF) pair. */
- OP_OBJC_SELF,
-
- /* Objective C: "@selector" pseudo-operator */
- OP_OBJC_SELECTOR,
-
- /* OP_SCOPE surrounds a type name and a field name. The type
- name is encoded as one element, but the field name stays as
- a string, which, of course, is variable length. */
- OP_SCOPE,
-
- /* Used to represent named structure field values in brace
- initializers (or tuples as they are called in (the deleted)
- Chill).
-
- The gcc C syntax is NAME:VALUE or .NAME=VALUE, the (the
- deleted) Chill syntax is .NAME:VALUE. Multiple labels (as in
- the (the deleted) Chill syntax .NAME1,.NAME2:VALUE) is
- represented as if it were .NAME1:(.NAME2:VALUE) (though that is
- not valid (the deleted) Chill syntax).
-
- The NAME is represented as for STRUCTOP_STRUCT; VALUE follows. */
- OP_LABELED,
-
- /* OP_TYPE is for parsing types, and used with the "ptype" command
- so we can look up types that are qualified by scope, either with
- the GDB "::" operator, or the Modula-2 '.' operator. */
- OP_TYPE,
-
- /* An un-looked-up identifier. */
- OP_NAME,
-
- /* An Objective C Foundation Class NSString constant */
- OP_OBJC_NSSTRING,
-
- /* A F90 array range operator (for "exp:exp", "exp:", ":exp" and ":"). */
- OP_F90_RANGE,
-
- /* OP_DECFLOAT is followed by a type pointer in the next exp_element
- and a dec long constant value in the following exp_element.
- Then comes another OP_DECFLOAT. */
- OP_DECFLOAT,
-
- /* First extension operator. Individual language modules define
- extra operators they need as constants with values
- OP_LANGUAGE_SPECIFIC0 + k, for k >= 0, using a separate
- enumerated type definition:
- enum foo_extension_operator {
- BINOP_MOGRIFY = OP_EXTENDED0,
- BINOP_FROB,
- ...
- }; */
- OP_EXTENDED0,
-
- /* Last possible extension operator. Defined to provide an
- explicit and finite number of extended operators. */
- OP_EXTENDED_LAST = 0xff
- /* NOTE: Eventually, we expect to convert to an object-oriented
- formulation for expression operators that does away with the
- need for these extension operators, and indeed for this
- entire enumeration type. Therefore, consider the OP_EXTENDED
- definitions to be a temporary measure. */
+#undef OP
};
-union exp_element
+/* Values of NOSIDE argument to eval_subexp. */
+
+enum noside
{
- enum exp_opcode opcode;
- struct symbol *symbol;
- LONGEST longconst;
- DOUBLEST doubleconst;
- gdb_byte decfloatconst[16];
- /* Really sizeof (union exp_element) characters (or less for the last
- element of a string). */
- char string;
- struct type *type;
- struct internalvar *internalvar;
- struct block *block;
- struct objfile *objfile;
+ EVAL_NORMAL,
+ EVAL_AVOID_SIDE_EFFECTS /* Don't modify any variables or
+ call any functions. The value
+ returned will have the correct
+ type, and will have an
+ approximately correct lvalue
+ type (inaccuracy: anything that is
+ listed as being in a register in
+ the function in which it was
+ declared will be lval_register).
+ Ideally this would not even read
+ target memory, but currently it
+ does in many situations. */
};
+struct expression;
+struct agent_expr;
+struct axs_value;
+struct type;
+struct ui_file;
+
+namespace expr
+{
+
+class operation;
+typedef std::unique_ptr<operation> operation_up;
+
+/* Base class for an operation. An operation is a single component of
+ an expression. */
+
+class operation
+{
+protected:
+
+ operation () = default;
+ DISABLE_COPY_AND_ASSIGN (operation);
+
+public:
+
+ virtual ~operation () = default;
+
+ /* Evaluate this operation. */
+ virtual value *evaluate (struct type *expect_type,
+ struct expression *exp,
+ enum noside noside) = 0;
+
+ /* Evaluate this operation in a context where C-like coercion is
+ needed. */
+ virtual value *evaluate_with_coercion (struct expression *exp,
+ enum noside noside)
+ {
+ return evaluate (nullptr, exp, noside);
+ }
+
+ /* Evaluate this expression in the context of a cast to
+ EXPECT_TYPE. */
+ virtual value *evaluate_for_cast (struct type *expect_type,
+ struct expression *exp,
+ enum noside noside);
+
+ /* Evaluate this expression in the context of a sizeof
+ operation. */
+ virtual value *evaluate_for_sizeof (struct expression *exp,
+ enum noside noside);
+
+ /* Evaluate this expression in the context of an address-of
+ operation. Must return the address. */
+ virtual value *evaluate_for_address (struct expression *exp,
+ enum noside noside);
+
+ /* Evaluate a function call, with this object as the callee.
+ EXPECT_TYPE, EXP, and NOSIDE have the same meaning as in
+ 'evaluate'. ARGS holds the operations that should be evaluated
+ to get the arguments to the call. */
+ virtual value *evaluate_funcall (struct type *expect_type,
+ struct expression *exp,
+ enum noside noside,
+ const std::vector<operation_up> &args)
+ {
+ /* Defer to the helper overload. */
+ return evaluate_funcall (expect_type, exp, noside, nullptr, args);
+ }
+
+ /* True if this is a constant expression. */
+ virtual bool constant_p () const
+ { return false; }
+
+ /* Return true if this operation uses OBJFILE (and will become
+ dangling when OBJFILE is unloaded), otherwise return false.
+ OBJFILE must not be a separate debug info file. */
+ virtual bool uses_objfile (struct objfile *objfile) const
+ { return false; }
+
+ /* Generate agent expression bytecodes for this operation. */
+ void generate_ax (struct expression *exp, struct agent_expr *ax,
+ struct axs_value *value,
+ struct type *cast_type = nullptr);
+
+ /* Return the opcode that is implemented by this operation. */
+ virtual enum exp_opcode opcode () const = 0;
+
+ /* Print this operation to STREAM. */
+ virtual void dump (struct ui_file *stream, int depth) const = 0;
+
+ /* Call to indicate that this is the outermost operation in the
+ expression. This should almost never be overridden. */
+ virtual void set_outermost () { }
+
+protected:
+
+ /* A helper overload that wraps evaluate_subexp_do_call. */
+ value *evaluate_funcall (struct type *expect_type,
+ struct expression *exp,
+ enum noside noside,
+ const char *function_name,
+ const std::vector<operation_up> &args);
+
+ /* Called by generate_ax to do the work for this particular
+ operation. */
+ virtual void do_generate_ax (struct expression *exp,
+ struct agent_expr *ax,
+ struct axs_value *value,
+ struct type *cast_type)
+ {
+ error (_("Cannot translate to agent expression"));
+ }
+};
+
+/* A helper function for creating an operation_up, given a type. */
+template<typename T, typename... Arg>
+operation_up
+make_operation (Arg... args)
+{
+ return operation_up (new T (std::forward<Arg> (args)...));
+}
+
+}
+
struct expression
+{
+ expression (const struct language_defn *lang, struct gdbarch *arch)
+ : language_defn (lang),
+ gdbarch (arch)
{
- const struct language_defn *language_defn; /* language it was entered in */
- int nelts;
- union exp_element elts[1];
- };
+ }
-/* Macros for converting between number of expression elements and bytes
- to store that many expression elements. */
+ DISABLE_COPY_AND_ASSIGN (expression);
-#define EXP_ELEM_TO_BYTES(elements) \
- ((elements) * sizeof (union exp_element))
-#define BYTES_TO_EXP_ELEM(bytes) \
- (((bytes) + sizeof (union exp_element) - 1) / sizeof (union exp_element))
+ /* Return the opcode for the outermost sub-expression of this
+ expression. */
+ enum exp_opcode first_opcode () const
+ {
+ return op->opcode ();
+ }
-/* From parse.c */
+ /* Evaluate the expression. EXPECT_TYPE is the context type of the
+ expression; normally this should be nullptr. NOSIDE controls how
+ evaluation is performed. */
+ struct value *evaluate (struct type *expect_type, enum noside noside);
-extern struct expression *parse_expression (char *);
+ /* Language it was entered in. */
+ const struct language_defn *language_defn;
+ /* Architecture it was parsed in. */
+ struct gdbarch *gdbarch;
+ expr::operation_up op;
+};
-extern struct type *parse_field_expression (char *, char **);
+typedef std::unique_ptr<expression> expression_up;
-extern struct expression *parse_exp_1 (char **, struct block *, int);
+/* From parse.c */
-/* For use by parsers; set if we want to parse an expression and
- attempt to complete a field name. */
-extern int in_parse_field;
+class innermost_block_tracker;
+extern expression_up parse_expression (const char *,
+ innermost_block_tracker * = nullptr,
+ bool void_context_p = false);
-/* The innermost context required by the stack and register variables
- we've encountered so far. To use this, set it to NULL, then call
- parse_<whatever>, then look at it. */
-extern struct block *innermost_block;
+extern expression_up parse_expression_with_language (const char *string,
+ enum language lang);
-/* From eval.c */
+extern struct type *parse_expression_for_completion
+ (const char *, gdb::unique_xmalloc_ptr<char> *, enum type_code *);
-/* Values of NOSIDE argument to eval_subexp. */
+class innermost_block_tracker;
+extern expression_up parse_exp_1 (const char **, CORE_ADDR pc,
+ const struct block *, int,
+ innermost_block_tracker * = nullptr);
-enum noside
- {
- EVAL_NORMAL,
- EVAL_SKIP, /* Only effect is to increment pos. */
- EVAL_AVOID_SIDE_EFFECTS /* Don't modify any variables or
- call any functions. The value
- returned will have the correct
- type, and will have an
- approximately correct lvalue
- type (inaccuracy: anything that is
- listed as being in a register in
- the function in which it was
- declared will be lval_register). */
- };
+/* From eval.c */
-extern struct value *evaluate_subexp_standard
- (struct type *, struct expression *, int *, enum noside);
+/* Evaluate a function call. The function to be called is in CALLEE and
+ the arguments passed to the function are in ARGVEC.
+ FUNCTION_NAME is the name of the function, if known.
+ DEFAULT_RETURN_TYPE is used as the function's return type if the return
+ type is unknown. */
-/* From expprint.c */
+extern struct value *evaluate_subexp_do_call (expression *exp,
+ enum noside noside,
+ value *callee,
+ gdb::array_view<value *> argvec,
+ const char *function_name,
+ type *default_return_type);
-extern void print_expression (struct expression *, struct ui_file *);
+/* From expprint.c */
-extern char *op_string (enum exp_opcode);
+extern const char *op_name (enum exp_opcode opcode);
-extern void dump_raw_expression (struct expression *, struct ui_file *, char *);
extern void dump_prefix_expression (struct expression *, struct ui_file *);
+/* In an OP_RANGE expression, either bound could be empty, indicating
+ that its value is by default that of the corresponding bound of the
+ array or string. Also, the upper end of the range can be exclusive
+ or inclusive. So we have six sorts of subrange. This enumeration
+ type is to identify this. */
+
+enum range_flag : unsigned
+{
+ /* This is a standard range. Both the lower and upper bounds are
+ defined, and the bounds are inclusive. */
+ RANGE_STANDARD = 0,
+
+ /* The low bound was not given. */
+ RANGE_LOW_BOUND_DEFAULT = 1 << 0,
+
+ /* The high bound was not given. */
+ RANGE_HIGH_BOUND_DEFAULT = 1 << 1,
+
+ /* The high bound of this range is exclusive. */
+ RANGE_HIGH_BOUND_EXCLUSIVE = 1 << 2,
+
+ /* The range has a stride. */
+ RANGE_HAS_STRIDE = 1 << 3,
+};
+
+DEF_ENUM_FLAGS_TYPE (enum range_flag, range_flags);
+
#endif /* !defined (EXPRESSION_H) */
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