| Debugging with GDB: Symbols In Guile |
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Next: Symbol Tables In Guile, Previous: Blocks In Guile, Up: Guile API [Contents][Index]
GDB represents every variable, function and type as an
entry in a symbol table. See Examining the Symbol Table.
Guile represents these symbols in GDB with the
<gdb:symbol> object.
The following symbol-related procedures are provided by the
(gdb) module:
Return #t if object is an object of type <gdb:symbol>.
Otherwise return #f.
Return #t if the <gdb:symbol> object is valid,
#f if not. A <gdb:symbol> object can become invalid if
the symbol it refers to does not exist in GDB any longer.
All other <gdb:symbol> procedures will throw an exception if it is
invalid at the time the procedure is called.
Return the type of symbol or #f if no type is recorded.
The result is an object of type <gdb:type>.
See Types In Guile.
Return the symbol table in which symbol appears.
The result is an object of type <gdb:symtab>.
See Symbol Tables In Guile.
Return the line number in the source code at which symbol was defined. This is an integer.
Return the name of symbol, as used by the linker (i.e., may be mangled).
Return the name of symbol in a form suitable for output. This is either
name or linkage_name, depending on whether the user
asked GDB to display demangled or mangled names.
Return the address class of the symbol. This classifies how to find the value
of a symbol. Each address class is a constant defined in the
(gdb) module and described later in this chapter.
Return #t if evaluating symbol’s value requires a frame
(see Frames In Guile) and #f otherwise. Typically,
local variables will require a frame, but other symbols will not.
Return #t if symbol is an argument of a function.
Otherwise return #f.
Return #t if symbol is a function or a method.
Otherwise return #f.
Compute the value of symbol, as a <gdb:value>. For
functions, this computes the address of the function, cast to the
appropriate type. If the symbol requires a frame in order to compute
its value, then frame must be given. If frame is not
given, or if frame is invalid, then an exception is thrown.
This function searches for a symbol by name. The search scope can be restricted to the parameters defined in the optional domain and block arguments.
name is the name of the symbol. It must be a string. The
optional block argument restricts the search to symbols visible
in that block. The block argument must be a
<gdb:block> object. If omitted, the block for the current frame
is used. The optional domain argument restricts
the search to the domain type. The domain argument must be a
domain constant defined in the (gdb) module and described later
in this chapter.
The result is a list of two elements.
The first element is a <gdb:symbol> object or #f if the symbol
is not found.
If the symbol is found, the second element is #t if the symbol
is a field of a method’s object (e.g., this in C++),
otherwise it is #f.
If the symbol is not found, the second element is #f.
This function searches for a global symbol by name. The search scope can be restricted by the domain argument.
name is the name of the symbol. It must be a string.
The optional domain argument restricts the search to the domain type.
The domain argument must be a domain constant defined in the (gdb)
module and described later in this chapter.
The result is a <gdb:symbol> object or #f if the symbol
is not found.
The available domain categories in <gdb:symbol> are represented
as constants in the (gdb) module:
SYMBOL_UNDEF_DOMAIN
This is used when a domain has not been discovered or none of the following domains apply. This usually indicates an error either in the symbol information or in GDB’s handling of symbols.
SYMBOL_VAR_DOMAIN
This domain contains variables, function names, typedef names and enum type values.
SYMBOL_STRUCT_DOMAIN
This domain holds struct, union and enum type names.
SYMBOL_LABEL_DOMAIN
This domain contains names of labels (for gotos).
SYMBOL_VARIABLES_DOMAIN
This domain holds a subset of the SYMBOLS_VAR_DOMAIN; it
contains everything minus functions and types.
SYMBOL_FUNCTIONS_DOMAIN
This domain contains all functions.
SYMBOL_TYPES_DOMAIN
This domain contains all types.
The available address class categories in <gdb:symbol> are represented
as constants in the gdb module:
SYMBOL_LOC_UNDEF
If this is returned by address class, it indicates an error either in the symbol information or in GDB’s handling of symbols.
SYMBOL_LOC_CONST
Value is constant int.
SYMBOL_LOC_STATIC
Value is at a fixed address.
SYMBOL_LOC_REGISTER
Value is in a register.
SYMBOL_LOC_ARG
Value is an argument. This value is at the offset stored within the symbol inside the frame’s argument list.
SYMBOL_LOC_REF_ARG
Value address is stored in the frame’s argument list. Just like
LOC_ARG except that the value’s address is stored at the
offset, not the value itself.
SYMBOL_LOC_REGPARM_ADDR
Value is a specified register. Just like LOC_REGISTER except
the register holds the address of the argument instead of the argument
itself.
SYMBOL_LOC_LOCAL
Value is a local variable.
SYMBOL_LOC_TYPEDEF
Value not used. Symbols in the domain SYMBOL_STRUCT_DOMAIN all
have this class.
SYMBOL_LOC_BLOCK
Value is a block.
SYMBOL_LOC_CONST_BYTES
Value is a byte-sequence.
SYMBOL_LOC_UNRESOLVED
Value is at a fixed address, but the address of the variable has to be determined from the minimal symbol table whenever the variable is referenced.
SYMBOL_LOC_OPTIMIZED_OUT
The value does not actually exist in the program.
SYMBOL_LOC_COMPUTED
The value’s address is a computed location.
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