ip2k.h

gcc-you can use this code to learn something about gcc, and inquire further into linux,

   FUNTYPE is a C variable whose value is a tree node that describes
   the function in question.  Normally it is a node of type
   `FUNCTION_TYPE' that describes the data type of the function.
   From this it is possible to obtain the data types of the value and
   arguments (if known).

   When a call to a library function is being considered, FUNDECL
   will contain an identifier node for the library function.  Thus, if
   you need to distinguish among various library functions, you can
   do so by their names.  Note that "library function" in this
   context means a function used to perform arithmetic, whose name is
   known specially in the compiler and was not mentioned in the C
   code being compiled.

   STACK-SIZE is the number of bytes of arguments passed on the
   stack.  If a variable number of bytes is passed, it is zero, and
   argument popping will always be the responsibility of the calling
   function.

   On the VAX, all functions always pop their arguments, so the
   definition of this macro is STACK-SIZE.  On the 68000, using the
   standard calling convention, no functions pop their arguments, so
   the value of the macro is always 0 in this case.  But an
   alternative calling convention is available in which functions
   that take a fixed number of arguments pop them but other functions
   (such as `printf') pop nothing (the caller pops all).  When this
   convention is in use, FUNTYPE is examined to determine whether a
   function takes a fixed number of arguments.  */

#define FUNCTION_ARG(CUM, MODE, TYPE, NAMED) 0
/* A C expression that controls whether a function argument is passed
   in a register, and which register.

   The arguments are CUM, which summarizes all the previous
   arguments; MODE, the machine mode of the argument; TYPE, the data
   type of the argument as a tree node or 0 if that is not known
   (which happens for C support library functions); and NAMED, which
   is 1 for an ordinary argument and 0 for nameless arguments that
   correspond to `...' in the called function's prototype.

   The value of the expression is usually either a `reg' RTX for the
   hard register in which to pass the argument, or zero to pass the
   argument on the stack.

   For machines like the VAX and 68000, where normally all arguments
   are pushed, zero suffices as a definition.

   The value of the expression can also be a `parallel' RTX.  This is
   used when an argument is passed in multiple locations.  The mode
   of the of the `parallel' should be the mode of the entire
   argument.  The `parallel' holds any number of `expr_list' pairs;
   each one describes where part of the argument is passed.  In each
   `expr_list', the first operand can be either a `reg' RTX for the
   hard register in which to pass this part of the argument, or zero
   to pass the argument on the stack.  If this operand is a `reg',
   then the mode indicates how large this part of the argument is.
   The second operand of the `expr_list' is a `const_int' which gives
   the offset in bytes into the entire argument where this part
   starts.

   The usual way to make the ANSI library `stdarg.h' work on a machine
   where some arguments are usually passed in registers, is to 	cause
   nameless arguments to be passed on the stack instead.  This is done
   by making `FUNCTION_ARG' return 0 whenever NAMED is 0.

   You may use the macro `MUST_PASS_IN_STACK (MODE, TYPE)' in the
   definition of this macro to determine if this argument is of a
   type that must be passed in the stack.  If `REG_PARM_STACK_SPACE'
   is not defined and `FUNCTION_ARG' returns nonzero for such an
   argument, the compiler will abort.  If `REG_PARM_STACK_SPACE' is
   defined, the argument will be computed in the stack and then
   loaded into a register.  */

#define CUMULATIVE_ARGS	int

/* A C type for declaring a variable that is used as the first
   argument of `FUNCTION_ARG' and other related values.  For some
   target machines, the type `int' suffices and can hold the number
   of bytes of argument so far.

   There is no need to record in `CUMULATIVE_ARGS' anything about the
   arguments that have been passed on the stack.  The compiler has
   other variables to keep track of that.  For target machines on
   which all arguments are passed on the stack, there is no need to
   store anything in `CUMULATIVE_ARGS'; however, the data structure
   must exist and should not be empty, so use `int'.  */

#define INIT_CUMULATIVE_ARGS(CUM, FNTYPE, LIBNAME, INDIRECT) \
  ((CUM) = 0)

/* A C statement (sans semicolon) for initializing the variable CUM
   for the state at the beginning of the argument list.  The variable
   has type `CUMULATIVE_ARGS'.  The value of FNTYPE is the tree node
   for the data type of the function which will receive the args, or 0
   if the args are to a compiler support library function.  The value
   of INDIRECT is nonzero when processing an indirect call, for
   example a call through a function pointer.  The value of INDIRECT
   is zero for a call to an explicitly named function, a library
   function call, or when `INIT_CUMULATIVE_ARGS' is used to find
   arguments for the function being compiled.
   
   When processing a call to a compiler support library function,
   LIBNAME identifies which one.  It is a `symbol_ref' rtx which
   contains the name of the function, as a string.  LIBNAME is 0 when
   an ordinary C function call is being processed.  Thus, each time
   this macro is called, either LIBNAME or FNTYPE is nonzero, but
   never both of them at once.  */

#define FUNCTION_ARG_ADVANCE(CUM, MODE, TYPE, NAMED)

/* All arguments are passed on stack - do nothing here.  */

/* A C statement (sans semicolon) to update the summarizer variable
   CUM to advance past an argument in the argument list.  The values
   MODE, TYPE and NAMED describe that argument.  Once this is done,
   the variable CUM is suitable for analyzing the *following*
   argument with `FUNCTION_ARG', etc.
   
   This macro need not do anything if the argument in question was
   passed on the stack.  The compiler knows how to track the amount
   of stack space used for arguments without any special help.  */

#define FUNCTION_ARG_REGNO_P(R) 0
/* A C expression that is nonzero if REGNO is the number of a hard
   register in which function arguments are sometimes passed.  This
   does *not* include implicit arguments such as the static chain and
   the structure-value address.  On many machines, no registers can be
   used for this purpose since all function arguments are pushed on
   the stack.  */

#define FUNCTION_VALUE(VALTYPE, FUNC) 				\
   ((TYPE_MODE (VALTYPE) == QImode)				\
    ? gen_rtx_REG (TYPE_MODE (VALTYPE), REG_RESULT + 1)	\
    : gen_rtx_REG (TYPE_MODE (VALTYPE), REG_RESULT))

/* Because functions returning 'char' actually widen to 'int', we have to
   use $81 as the return location if we think we only have a 'char'.  */

/* A C expression to create an RTX representing the place where a
   function returns a value of data type VALTYPE.  VALTYPE is a tree
   node representing a data type.  Write `TYPE_MODE (VALTYPE)' to get
   the machine mode used to represent that type.  On many machines,
   only the mode is relevant.  (Actually, on most machines, scalar
   values are returned in the same place regardless of mode).

   The value of the expression is usually a `reg' RTX for the hard
   register where the return value is stored.  The value can also be a
   `parallel' RTX, if the return value is in multiple places.  See
   `FUNCTION_ARG' for an explanation of the `parallel' form.

   If `PROMOTE_FUNCTION_RETURN' is defined, you must apply the same
   promotion rules specified in `PROMOTE_MODE' if VALTYPE is a scalar
   type.

   If the precise function being called is known, FUNC is a tree node
   (`FUNCTION_DECL') for it; otherwise, FUNC is a null pointer.  This
   makes it possible to use a different value-returning convention
   for specific functions when all their calls are known.

   `FUNCTION_VALUE' is not used for return vales with aggregate data
   types, because these are returned in another way.  See
   `STRUCT_VALUE_REGNUM' and related macros, below.  */

#define LIBCALL_VALUE(MODE)  gen_rtx_REG ((MODE), REG_RESULT)
/* A C expression to create an RTX representing the place where a
   library function returns a value of mode MODE.  If the precise
   function being called is known, FUNC is a tree node
   (`FUNCTION_DECL') for it; otherwise, FUNC is a null pointer.  This
   makes it possible to use a different value-returning convention
   for specific functions when all their calls are known.

   Note that "library function" in this context means a compiler
   support routine, used to perform arithmetic, whose name is known
   specially by the compiler and was not mentioned in the C code being
   compiled.

   The definition of `LIBRARY_VALUE' need not be concerned aggregate
   data types, because none of the library functions returns such
   types.  */

#define FUNCTION_VALUE_REGNO_P(N) ((N) == REG_RESULT)
/* A C expression that is nonzero if REGNO is the number of a hard
   register in which the values of called function may come back.

   A register whose use for returning values is limited to serving as
   the second of a pair (for a value of type `double', say) need not
   be recognized by this macro.  So for most machines, this definition
   suffices:

   #define FUNCTION_VALUE_REGNO_P(N) ((N) == 0)

   If the machine has register windows, so that the caller and the
   called function use different registers for the return value, this
   macro should recognize only the caller's register numbers.  */

#define RETURN_IN_MEMORY(TYPE) \
  ((TYPE_MODE (TYPE) == BLKmode) ? int_size_in_bytes (TYPE) > 8 : 0)
/* A C expression which can inhibit the returning of certain function
   values in registers, based on the type of value.  A nonzero value
   says to return the function value in memory, just as large
   structures are always returned.  Here TYPE will be a C expression
   of type `tree', representing the data type of the value.

   Note that values of mode `BLKmode' must be explicitly handled by
   this macro.  Also, the option `-fpcc-struct-return' takes effect
   regardless of this macro.  On most systems, it is possible to
   leave the macro undefined; this causes a default definition to be
   used, whose value is the constant 1 for `BLKmode' values, and 0
   otherwise.

   Do not use this macro to indicate that structures and unions
   should always be returned in memory.  You should instead use
   `DEFAULT_PCC_STRUCT_RETURN' to indicate this.  */

/* Indicate that large structures are passed by reference.  */
#define FUNCTION_ARG_PASS_BY_REFERENCE(CUM,MODE,TYPE,NAMED)	0


#define DEFAULT_PCC_STRUCT_RETURN 0
/* Define this macro to be 1 if all structure and union return values
   must be in memory.  Since this results in slower code, this should
   be defined only if needed for compatibility with other compilers
   or with an ABI.  If you define this macro to be 0, then the
   conventions used for structure and union return values are decided
   by the `RETURN_IN_MEMORY' macro.

   If not defined, this defaults to the value 1.  */

#define STRUCT_VALUE 0
/* If the structure value address is not passed in a register, define
   `STRUCT_VALUE' as an expression returning an RTX for the place
   where the address is passed.  If it returns 0, the address is
   passed as an "invisible" first argument.  */

#define STRUCT_VALUE_INCOMING 0
/* If the incoming location is not a register, then you should define
   `STRUCT_VALUE_INCOMING' as an expression for an RTX for where the
   called function should find the value.  If it should find the
   value on the stack, define this to create a `mem' which refers to
   the frame pointer.  A definition of 0 means that the address is
   passed as an "invisible" first argument.  */

#define EPILOGUE_USES(REGNO) 0
/* Define this macro as a C expression that is nonzero for registers
   are used by the epilogue or the `return' pattern.  The stack and
   frame pointer registers are already be assumed to be used as
   needed.  */

#define SETUP_INCOMING_VARARGS(ARGS_SO_FAR,MODE,TYPE,		\
			       PRETEND_ARGS_SIZE,SECOND_TIME)	\
  ((PRETEND_ARGS_SIZE) = (0))


/*  Hmmm.  We don't actually like constants as addresses - they always need
    to be loaded to a register, except for function calls which take an
    address by immediate value.  But changing this to zero had negative
    effects, causing the compiler to get very confused....  */

#define CONSTANT_ADDRESS_P(X) CONSTANT_P (X)

/* A C expression that is 1 if the RTX X is a constant which is a
   valid address.  On most machines, this can be defined as
   `CONSTANT_P (X)', but a few machines are more restrictive in which
   constant addresses are supported.

   `CONSTANT_P' accepts integer-values expressions whose values are
   not explicitly known, such as `symbol_ref', `label_ref', and
   `high' expressions and `const' arithmetic expressions, in addition
   to `const_int' and `const_double' expressions.  */

#define MAX_REGS_PER_ADDRESS 1
/* A number, the maximum number of registers that can appear in a
   valid memory address.  Note that it is up to you to specify a
   value equal to the maximum number that `GO_IF_LEGITIMATE_ADDRESS'
   would ever accept.  */

#ifdef REG_OK_STRICT
#  define GO_IF_LEGITIMATE_ADDRESS(MODE, OPERAND, ADDR)	\
{							\
  if (legitimate_address_p ((MODE), (OPERAND), 1))	\
    goto ADDR;						\
}
#else
#  define GO_IF_LEGITIMATE_ADDRESS(MODE, OPERAND, ADDR)	\
{							\
  if (legitimate_address_p ((MODE), (OPERAND), 0))	\
    goto ADDR;						\
}
#endif
/* A C compound statement with a conditional `goto LABEL;' executed
   if X (an RTX) is a legitimate memory address on the target machine
   for a memory operand of mode MODE.

   It usually pays to define several simpler macros to serve as
   subroutines for this one.  Otherwise it may be too complicated to
   understand.

   This macro must exist in two variants: a strict variant and a
   non-strict one.  The strict variant is used in the reload pass.  It
   must be defined so that any pseudo-register that has not been
   allocated a hard register is considered a memory reference.  I