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Diffstat (limited to 'gdb/symseg.h')
| -rw-r--r-- | gdb/symseg.h | 323 |
1 files changed, 323 insertions, 0 deletions
diff --git a/gdb/symseg.h b/gdb/symseg.h new file mode 100644 index 0000000..11f4807 --- /dev/null +++ b/gdb/symseg.h @@ -0,0 +1,323 @@ +/* GDB symbol table format definitions. + Copyright (C) 1986 Free Software Foundation, Inc. + +GDB is distributed in the hope that it will be useful, but WITHOUT ANY +WARRANTY. No author or distributor accepts responsibility to anyone +for the consequences of using it or for whether it serves any +particular purpose or works at all, unless he says so in writing. +Refer to the GDB General Public License for full details. + +Everyone is granted permission to copy, modify and redistribute GDB, +but only under the conditions described in the GDB General Public +License. A copy of this license is supposed to have been given to you +along with GDB so you can know your rights and responsibilities. It +should be in a file named COPYING. Among other things, the copyright +notice and this notice must be preserved on all copies. + +In other words, go ahead and share GDB, but don't try to stop +anyone else from sharing it farther. Help stamp out software hoarding! +*/ + +/* Format of GDB symbol table data. + There is one symbol segment for each source file or + independant compilation. These segments are simply concatenated + to form the GDB symbol table. A zero word where the beginning + of a segment is expected indicates there are no more segments. + +Format of a symbol segment: + + The symbol segment begins with a word containing 1 + if it is in the format described here. Other formats may + be designed, with other code numbers. + + The segment contains many objects which point at each other. + The pointers are offsets in bytes from the beginning of the segment. + Thus, each segment can be loaded into core and its pointers relocated + to make valid in-core pointers. + + All the data objects in the segment can be found indirectly from + one of them, the root object, of type `struct symbol_root'. + It appears at the beginning of the segment. + + The total size of the segment, in bytes, appears as the `length' + field of this object. This size includes the size of the + root object. + + All the object data types are defined here to contain pointer types + appropriate for in-core use on a relocated symbol segment. + Casts to and from type int are required for working with + unrelocated symbol segments such as are found in the file. + + The ldsymaddr word is filled in by the loader to contain + the offset (in bytes) within the ld symbol table + of the first nonglobal symbol from this compilation. + This makes it possible to match those symbols + (which contain line number information) reliably with + the segment they go with. + + Core addresses within the program that appear in the symbol segment + are not relocated by the loader. They are inserted by the assembler + and apply to addresses as output by the assembler, so GDB must + relocate them when it loads the symbol segment. It gets the information + on how to relocate from the textrel, datarel, bssrel, databeg and bssbeg + words of the root object. + + The words textrel, datarel and bssrel + are filled in by ld with the amounts to relocate within-the-file + text, data and bss addresses by; databeg and bssbeg can be + used to tell which kind of relocation an address needs. */ + +enum language {language_c}; + +struct symbol_root +{ + int format; /* Data format version */ + int length; /* # bytes in this symbol segment */ + int ldsymoff; /* Offset in ld symtab of this file's syms */ + int textrel; /* Relocation for text addresses */ + int datarel; /* Relocation for data addresses */ + int bssrel; /* Relocation for bss addresses */ + char *filename; /* Name of source file compiled */ + char *filedir; /* Name of directory it was reached from */ + struct blockvector *blockvector; /* Vector of all symbol naming blocks */ + struct typevector *typevector; /* Vector of all data types */ + enum language language; /* Code identifying the language used */ + char *version; /* Version info. Not fully specified */ + char *compilation; /* Compilation info. Not fully specified */ + int databeg; /* Address within the file of data start */ + int bssbeg; /* Address within the file of bss start */ +}; + +/* All data types of symbols in the compiled program + are represented by `struct type' objects. + All of these objects are pointed to by the typevector. + The type vector may have empty slots that contain zero. */ + +struct typevector +{ + int length; + struct type *type[1]; +}; + +/* Different kinds of data types are distinguished by the `code' field. */ + +enum type_code +{ + TYPE_CODE_UNDEF, /* Not used; catches errors */ + TYPE_CODE_PTR, /* Pointer type */ + TYPE_CODE_ARRAY, /* Array type, lower bound zero */ + TYPE_CODE_STRUCT, /* C struct or Pascal record */ + TYPE_CODE_UNION, /* C union or Pascal variant part */ + TYPE_CODE_ENUM, /* Enumeration type */ + TYPE_CODE_FUNC, /* Function type */ + TYPE_CODE_INT, /* Integer type */ + TYPE_CODE_FLT, /* Floating type */ + TYPE_CODE_VOID, /* Void type (values zero length) */ + TYPE_CODE_SET, /* Pascal sets */ + TYPE_CODE_RANGE, /* Range (integers within spec'd bounds) */ + TYPE_CODE_PASCAL_ARRAY, /* Array with explicit type of index */ +}; + +/* This appears in a type's flags word for an unsigned integer type. */ +#define TYPE_FLAG_UNSIGNED 1 + +/* Other flag bits are used with GDB. */ + +struct type +{ + /* Code for kind of type */ + enum type_code code; + /* Name of this type, or zero if none. + This is used for printing only. + Type names specified as input are defined by symbols. */ + char *name; + /* Length in bytes of storage for a value of this type */ + int length; + /* For a pointer type, describes the type of object pointed to. + For an array type, describes the type of the elements. + For a function type, describes the type of the value. + Unused otherwise. */ + struct type *target_type; + /* Type that is a pointer to this type. + Zero if no such pointer-to type is known yet. + The debugger may add the address of such a type + if it has to construct one later. */ + struct type *pointer_type; + /* Type that is a function returning this type. + Zero if no such function type is known here. + The debugger may add the address of such a type + if it has to construct one later. */ + struct type *function_type; + /* Flags about this type. */ + short flags; + /* Number of fields described for this type */ + short nfields; + /* For structure and union types, a description of each field. + For set and pascal array types, there is one "field", + whose type is the domain type of the set or array. + For range types, there are two "fields", + the minimum and maximum values (both inclusive). + For enum types, each possible value is described by one "field". + For range types, there are two "fields", that record constant values + (inclusive) for the minimum and maximum. + + Using a pointer to a separate array of fields + allows all types to have the same size, which is useful + because we can allocate the space for a type before + we know what to put in it. */ + struct field + { + /* Position of this field, counting in bits from start of + containing structure. For a function type, this is the + position in the argument list of this argument. + For a range bound or enum value, this is the value itself. */ + int bitpos; + /* Size of this field, in bits, or zero if not packed. + For an unpacked field, the field's type's length + says how many bytes the field occupies. */ + int bitsize; + /* In a struct or enum type, type of this field. + In a function type, type of this argument. + In an array type, the domain-type of the array. */ + struct type *type; + /* Name of field, value or argument. + Zero for range bounds and array domains. */ + char *name; + } *fields; +}; + +/* All of the name-scope contours of the program + are represented by `struct block' objects. + All of these objects are pointed to by the blockvector. + + Each block represents one name scope. + Each lexical context has its own block. + + The first two blocks in the blockvector are special. + The first one contains all the symbols defined in this compilation + whose scope is the entire program linked together. + The second one contains all the symbols whose scope is the + entire compilation excluding other separate compilations. + In C, these correspond to global symbols and static symbols. + + Each block records a range of core addresses for the code that + is in the scope of the block. The first two special blocks + give, for the range of code, the entire range of code produced + by the compilation that the symbol segment belongs to. + + The blocks appear in the blockvector + in order of increasing starting-address, + and, within that, in order of decreasing ending-address. + + This implies that within the body of one function + the blocks appear in the order of a depth-first tree walk. */ + +struct blockvector +{ + /* Number of blocks in the list. */ + int nblocks; + /* The blocks themselves. */ + struct block *block[1]; +}; + +struct block +{ + /* Addresses in the executable code that are in this block. + Note: in an unrelocated symbol segment in a file, + these are always zero. They can be filled in from the + N_LBRAC and N_RBRAC symbols in the loader symbol table. */ + int startaddr, endaddr; + /* The symbol that names this block, + if the block is the body of a function; + otherwise, zero. + Note: In an unrelocated symbol segment in an object file, + this field may be zero even when the block has a name. + That is because the block is output before the name + (since the name resides in a higher block). + Since the symbol does point to the block (as its value), + it is possible to find the block and set its name properly. */ + struct symbol *function; + /* The `struct block' for the containing block, or 0 if none. */ + /* Note that in an unrelocated symbol segment in an object file + this pointer may be zero when the correct value should be + the second special block (for symbols whose scope is one compilation). + This is because the compiler ouptuts the special blocks at the + very end, after the other blocks. */ + struct block *superblock; + /* Number of local symbols. */ + int nsyms; + /* The symbols. */ + struct symbol *sym[1]; +}; + +/* Represent one symbol name; a variable, constant, function or typedef. */ + +/* Different name spaces for symbols. Looking up a symbol specifies + a namespace and ignores symbol definitions in other name spaces. + + VAR_NAMESPACE is the usual namespace. + In C, this contains variables, function names, typedef names + and enum type values. + + STRUCT_NAMESPACE is used in C to hold struct, union and enum type names. + Thus, if `struct foo' is used in a C program, + it produces a symbol named `foo' in the STRUCT_NAMESPACE. + + LABEL_NAMESPACE may be used for names of labels (for gotos); + currently it is not used and labels are not recorded at all. */ + +/* For a non-global symbol allocated statically, + the correct core address cannot be determined by the compiler. + The compiler puts an index number into the symbol's value field. + This index number can be matched with the "desc" field of + an entry in the loader symbol table. */ + +enum namespace +{ + UNDEF_NAMESPACE, VAR_NAMESPACE, STRUCT_NAMESPACE, LABEL_NAMESPACE, +}; + +/* An address-class says where to find the value of the symbol in core. */ + +enum address_class +{ + LOC_UNDEF, /* Not used; catches errors */ + LOC_CONST, /* Value is constant int */ + LOC_STATIC, /* Value is at fixed address */ + LOC_REGISTER, /* Value is in register */ + LOC_ARG, /* Value is at spec'd position in arglist */ + LOC_LOCAL, /* Value is at spec'd pos in stack frame */ + LOC_TYPEDEF, /* Value not used; definition in SYMBOL_TYPE + Symbols in the namespace STRUCT_NAMESPACE + all have this class. */ + LOC_LABEL, /* Value is address in the code */ + LOC_BLOCK, /* Value is address of a `struct block'. + Function names have this class. */ + LOC_EXTERNAL, /* Value is at address not in this compilation. + This is used for .comm symbols + and for extern symbols within functions. + Inside GDB, this is changed to LOC_STATIC once the + real address is obtained from a loader symbol. */ + LOC_CONST_BYTES /* Value is a constant byte-sequence. */ +}; + +struct symbol +{ + /* Symbol name */ + char *name; + /* Name space code. */ + enum namespace namespace; + /* Address class */ + enum address_class class; + /* Data type of value */ + struct type *type; + /* constant value, or address if static, or register number, + or offset in arguments, or offset in stack frame. */ + union + { + long value; + struct block *block; /* for LOC_BLOCK */ + char *bytes; /* for LOC_CONST_BYTES */ + } + value; +}; |