tm-spur.h

这是完整的gcc源代码

/* Definitions of target machine for GNU compiler, for SPUR chip.
   Copyright (C) 1988 Free Software Foundation, Inc.

This file is part of GNU CC.

GNU CC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 1, or (at your option)
any later version.

GNU CC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU CC; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */


/* Note that some other tm- files include this one and then override
   many of the definitions that relate to assembler syntax.  */


/* Names to predefine in the preprocessor for this target machine.  */

#define CPP_PREDEFINES "-Dspur"

/* Print subsidiary information on the compiler version in use.  */
#define TARGET_VERSION fprintf (stderr, " (spur)");

/* Run-time compilation parameters selecting different hardware subsets.

   On the SPUR, we don't yet need any.  */

extern int target_flags;

/* Nonzero if we should generate code to use the fpu.  */
#define TARGET_FPU (target_flags & 1)

/* Nonzero if we should expand constant shifts into series of shift
   instructions.  */
#define TARGET_EXPAND_SHIFTS (target_flags & 2)

/* Nonzero if we should generate long jumps for compares. */
#define TARGET_LONG_JUMPS (target_flags & 4)

/* Macro to define tables used to set the flags.
   This is a list in braces of pairs in braces,
   each pair being { "NAME", VALUE }
   where VALUE is the bits to set or minus the bits to clear.
   An empty string NAME is used to identify the default VALUE.  */

#define TARGET_SWITCHES  \
  { {"fpu", 1},			\
    {"soft-float", -1},		\
    {"expand-shifts", 2},       \
    {"lib-shifts", -2},		\
    {"long-jumps", 4},		\
    {"short-jumps", -4},	\
    { "", TARGET_DEFAULT}}

#define TARGET_DEFAULT 0

/* target machine storage layout */

/* Define this if most significant bit is lowest numbered
   in instructions that operate on numbered bit-fields.
   This is a moot question on the SPUR due to the lack of bit-field insns.  */
/* #define BITS_BIG_ENDIAN */

/* Define this if most significant byte of a word is the lowest numbered.  */
/* That is not true on SPUR.  */
/* #define BYTES_BIG_ENDIAN */

/* Define this if most significant word of a multiword number is numbered.  */
/* For SPUR we can decide arbitrarily
   since there are no machine instructions for them.  */
/* #define WORDS_BIG_ENDIAN */

/* number of bits in an addressible storage unit */
#define BITS_PER_UNIT 8

/* Width in bits of a "word", which is the contents of a machine register.
   Note that this is not necessarily the width of data type `int';
   if using 16-bit ints on a 68000, this would still be 32.
   But on a machine with 16-bit registers, this would be 16.  */
#define BITS_PER_WORD 32

/* Width of a word, in units (bytes).  */
#define UNITS_PER_WORD 4

/* Width in bits of a pointer.
   See also the macro `Pmode' defined below.  */
#define POINTER_SIZE 32

/* Allocation boundary (in *bits*) for storing pointers in memory.  */
#define POINTER_BOUNDARY 32

/* Allocation boundary (in *bits*) for storing arguments in argument list.  */
#define PARM_BOUNDARY 64

/* Boundary (in *bits*) on which stack pointer should be aligned.  */
#define STACK_BOUNDARY 64

/* Allocation boundary (in *bits*) for the code of a function.  */
#define FUNCTION_BOUNDARY 32

/* Alignment of field after `int : 0' in a structure.  */
#define EMPTY_FIELD_BOUNDARY 32

/* Every structure's size must be a multiple of this.  */
#define STRUCTURE_SIZE_BOUNDARY 32

/* No data type wants to be aligned rounder than this.  */
#define BIGGEST_ALIGNMENT 64

/* Define this if move instructions will actually fail to work
   when given unaligned data.  */
#define STRICT_ALIGNMENT

/* Standard register usage.  */

/* Number of actual hardware registers.
   The hardware registers are assigned numbers for the compiler
   from 0 to just below FIRST_PSEUDO_REGISTER.
   All registers that the compiler knows about must be given numbers,
   even those that are not normally considered general registers.

   SPUR has 32 fullword registers and 15 floating point registers.  */

#define FIRST_PSEUDO_REGISTER 47

/* 1 for registers that have pervasive standard uses
   and are not available for the register allocator.
   On SPUR, this includes all the global registers
   and the callee return address register.  */
#define FIXED_REGISTERS  \
 {1, 1, 1, 1, 1, 1, 1, 1, 1, 1, \
  1, 0, 0, 0, 0, 0,		\
  0, 0, 0, 0, 0, 0, 0, 0, 1, 1,	\
  1, 0, 0, 0, 0, 0,		\
  1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}

/* 1 for registers not available across function calls.
   These must include the FIXED_REGISTERS and also any
   registers that can be used without being saved.
   The latter must include the registers where values are returned
   and the register where structure-value addresses are passed.
   Aside from that, you can include as many other registers as you like.  */
#define CALL_USED_REGISTERS  \
 {1, 1, 1, 1, 1, 1, 1, 1, 1, 1, \
  1, 0, 0, 0, 0, 0,		\
  0, 0, 0, 0, 0, 0, 0, 0, 1, 1,	\
  1, 1, 1, 1, 1, 1,		\
  1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0}

/* Return number of consecutive hard regs needed starting at reg REGNO
   to hold something of mode MODE.
   This is ordinarily the length in words of a value of mode MODE
   but can be less for certain modes in special long registers.

   On SPUR, ordinary registers hold 32 bits worth;
   a single floating point register is always enough for
   anything that can be stored in them at all.  */
#define HARD_REGNO_NREGS(REGNO, MODE)   \
  ((REGNO) >= 32 ? 1				\
   : ((GET_MODE_SIZE (MODE) + UNITS_PER_WORD - 1) / UNITS_PER_WORD))

/* Value is 1 if hard register REGNO can hold a value of machine-mode MODE.
   On SPUR, the cpu registers can hold any mode but the float registers
   can hold only SFmode or DFmode.  And they can't hold anything if use
   of hardware floating point is disabled.  */
#define HARD_REGNO_MODE_OK(REGNO, MODE) \
  (((REGNO) < 32 && (GET_MODE_SIZE (MODE) <= 4 || (REGNO) < 31))	\
   || (TARGET_FPU && ((MODE) == SFmode || (MODE) == DFmode)))

/* Value is 1 if it is a good idea to tie two pseudo registers
   when one has mode MODE1 and one has mode MODE2.
   If HARD_REGNO_MODE_OK could produce different values for MODE1 and MODE2,
   for any hard reg, then this must be 0 for correct output.  */
#define MODES_TIEABLE_P(MODE1, MODE2) \
  (((MODE1) == SFmode || (MODE1) == DFmode) \
   == ((MODE2) == SFmode || (MODE2) == DFmode))

/* Specify the registers used for certain standard purposes.
   The values of these macros are register numbers.  */

/* SPUR pc isn't overloaded on a register that the compiler knows about.  */
/* #define PC_REGNUM  */

/* Register to use for pushing function arguments.  */
#define STACK_POINTER_REGNUM 4

/* Base register for access to local variables of the function.  */
#define FRAME_POINTER_REGNUM 25

/* Value should be nonzero if functions must have frame pointers.
   Zero means the frame pointer need not be set up (and parms
   may be accessed via the stack pointer) in functions that seem suitable.
   This is computed in `reload', in reload1.c.  */
#define FRAME_POINTER_REQUIRED 1

/* Base register for access to arguments of the function.  */
#define ARG_POINTER_REGNUM 25

/* Register in which static-chain is passed to a function.  */
/* ??? */
#define STATIC_CHAIN_REGNUM 8

/* Register in which address to store a structure value
   is passed to a function.  */
#define STRUCT_VALUE_REGNUM 27
#define STRUCT_VALUE_INCOMING_REGNUM 11

/* Define the classes of registers for register constraints in the
   machine description.  Also define ranges of constants.

   One of the classes must always be named ALL_REGS and include all hard regs.
   If there is more than one class, another class must be named NO_REGS
   and contain no registers.

   The name GENERAL_REGS must be the name of a class (or an alias for
   another name such as ALL_REGS).  This is the class of registers
   that is allowed by "g" or "r" in a register constraint.
   Also, registers outside this class are allocated only when
   instructions express preferences for them.

   The classes must be numbered in nondecreasing order; that is,
   a larger-numbered class must never be contained completely
   in a smaller-numbered class.

   For any two classes, it is very desirable that there be another
   class that represents their union.  */
   
/* The 68000 has two kinds of registers, hence four classes.  */

enum reg_class { NO_REGS, GENERAL_REGS, FP_REGS, ALL_REGS, LIM_REG_CLASSES };

#define N_REG_CLASSES (int) LIM_REG_CLASSES

/* Give names of register classes as strings for dump file.   */

#define REG_CLASS_NAMES \
 {"NO_REGS", "GENERAL_REGS", "FP_REGS", "ALL_REGS" }

/* Define which registers fit in which classes.
   This is an initializer for a vector of HARD_REG_SET
   of length N_REG_CLASSES.  */

#define REG_CLASS_CONTENTS {{0, 0}, {-1, 0}, {0, 0x7fff}, {-1, 0x7fff}}

/* The same information, inverted:
   Return the class number of the smallest class containing
   reg number REGNO.  This could be a conditional expression
   or could index an array.  */

#define REGNO_REG_CLASS(REGNO) \
 ((REGNO) >= 32 ? FP_REGS : GENERAL_REGS)

/* The class value for index registers, and the one for base regs.  */
#define INDEX_REG_CLASS GENERAL_REGS
#define BASE_REG_CLASS GENERAL_REGS

/* Get reg_class from a letter such as appears in the machine description.  */

#define REG_CLASS_FROM_LETTER(C) \
  ((C) == 'f' ? FP_REGS : NO_REGS)

/* The letters I, J, K, L and M in a register constraint string
   can be used to stand for particular ranges of immediate operands.
   This macro defines what the ranges are.
   C is the letter, and VALUE is a constant value.
   Return 1 if VALUE is in the range specified by C.

   For SPUR, `I' is used for the range of constants an insn
   can actually contain.
   `J' is used for the range which is just zero (since that is R0).
   `K' is used for the 5-bit operand of a compare insns.  */

#define CONST_OK_FOR_LETTER_P(VALUE, C)  \
  ((C) == 'I' ? (unsigned) ((VALUE) + 0x2000) < 0x4000	\
   : (C) == 'J' ? (VALUE) == 0				\
   : (C) == 'K' ? (unsigned) (VALUE) < 0x20		\
   : 0)

/* Similar, but for floating constants, and defining letters G and H.
   Here VALUE is the CONST_DOUBLE rtx itself.  */

#define CONST_DOUBLE_OK_FOR_LETTER_P(VALUE, C)				\
  ((C) == 'G' && CONST_DOUBLE_LOW ((VALUE)) == 0			\
   && CONST_DOUBLE_HIGH ((VALUE)) == 0)

/* Given an rtx X being reloaded into a reg required to be
   in class CLASS, return the class of reg to actually use.
   In general this is just CLASS; but on some machines
   in some cases it is preferable to use a more restrictive class.  */
#define PREFERRED_RELOAD_CLASS(X,CLASS) (CLASS)

/* Return the maximum number of consecutive registers
   needed to represent mode MODE in a register of class CLASS.  */
/* On SPUR, this is the size of MODE in words,
   except in the FP regs, where a single reg is always enough.  */
#define CLASS_MAX_NREGS(CLASS, MODE)	\
 ((CLASS) == FP_REGS ? 1			\
  : ((GET_MODE_SIZE (MODE) + UNITS_PER_WORD - 1) / UNITS_PER_WORD))

/* Stack layout; function entry, exit and calling.  */

/* Define this if pushing a word on the stack
   makes the stack pointer a smaller address.  */
#define STACK_GROWS_DOWNWARD

/* Define this if the nominal address of the stack frame
   is at the high-address end of the local variables;
   that is, each additional local variable allocated
   goes at a more negative offset in the frame.  */
#define FRAME_GROWS_DOWNWARD

/* Offset within stack frame to start allocating local variables at.
   If FRAME_GROWS_DOWNWARD, this is the offset to the END of the
   first local allocated.  Otherwise, it is the offset to the BEGINNING
   of the first local allocated.  */
#define STARTING_FRAME_OFFSET 0

/* If we generate an insn to push BYTES bytes,
   this says how many the stack pointer really advances by.
   On SPUR, don't define this because there are no push insns.  */
/*  #define PUSH_ROUNDING(BYTES) */

/* Offset of first parameter from the argument pointer register value.  */
#define FIRST_PARM_OFFSET(FNDECL) 0

/* Value is 1 if returning from a function call automatically
   pops the arguments described by the number-of-args field in the call.
   FUNTYPE is the data type of the function (as a tree),
   or for a library call it is an identifier node for the subroutine name.  */

#define RETURN_POPS_ARGS(FUNTYPE) 0

/* Define how to find the value returned by a function.
   VALTYPE is the data type of the value (as a tree).
   If the precise function being called is known, FUNC is its FUNCTION_DECL;
   otherwise, FUNC is 0.  */