m68k.md

这是完整的gcc源代码

;;- Machine description for GNU compiler
;;- Motorola 68000 Version
;;   Copyright (C) 1987, 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.


;;- instruction definitions

;;- @@The original PO technology requires these to be ordered by speed,
;;- @@    so that assigner will pick the fastest.

;;- See file "rtl.def" for documentation on define_insn, match_*, et. al.

;;- When naming insn's (operand 0 of define_insn) be careful about using
;;- names from other targets machine descriptions.

;;- cpp macro #define NOTICE_UPDATE_CC in file tm.h handles condition code
;;- updates for most instructions.

;;- Operand classes for the register allocator:
;;- 'a' one of the address registers can be used.
;;- 'd' one of the data registers can be used.
;;- 'f' one of the m68881 registers can be used
;;- 'r' either a data or an address register can be used.
;;- 'x' if one of the Sun FPA registers                    
;;- 'y' if one of the Low Sun FPA registers (fpa0-fpa15).

;;- Immediate Floating point operator constraints
;;- 'G' a floating point constant that is *NOT* one of the standard
;;   68881 constant values (to force calling output_move_const_double
;;   to get it from rom if it is a 68881 constant).
;;- 'H' one of the standard FPA constant values
;;
;;   See the functions standard_XXX_constant_p in output-m68k.c for more
;; info.

;;- Immediate integer operand constraints:
;;- 'I'  1 .. 8
;;- 'J'  -32768 .. 32767
;;- 'K'  -128 .. 127
;;- 'L'  -8 .. -1

;;- 		FPA port explanation:

;;-		Usage of the Sun FPA and the 68881 together

;;- The current port of gcc to the sun fpa disallows use of the m68881
;;- instructions completely if code is targetted for the fpa.  This is
;;- for the following reasons:

;;- 1) Expressing the preference hierarchy (ie. use the fpa if you
;;- can, the 68881 otherwise, and data registers only if you are
;;- forced to it) is a bitch with the current constraint scheme,
;;- especially since it would have to work for any combination of
;;- -mfpa, -m68881.

;;- 2) There are no instructions to move between the two types of
;;- registers; the stack must be used as an intermediary.

;;- It could indeed be done; I think the best way would be to have
;;- seperate patterns for TARGET_FPA (which implies a 68881),
;;- TARGET_68881, and no floating point co-processor.  Use
;;- define_expands for all of the named instruction patterns, and
;;- include code in the FPA instruction to deal with the 68881 with
;;- preferences specifically set to favor the fpa.  Some of this has
;;- already been done:
;;-
;;- 	1) Separation of most of the patterns out into a TARGET_FPA
;;- case and a TARGET_68881 case (the exceptions are the patterns
;;- which would need one define_expand and three define_insn's under
;;- it (with alot of duplicate code between them) to replace the
;;- current single define_insn.  These are mov{[ds]f,[ds]i} and the
;;- first two patterns in the md.
;;-
;;- Some would still have to be done:
;;-
;;-	1) Add code to the fpa patterns which correspond to 68881
;;- patterns to deal with the 68881 case (including preferences!).
;;- What you might actually do here is combine the fpa and 68881 code
;;- back together into one pattern for those instructions where it's
;;- absolutely necessary and save yourself some duplicate code.  I'm
;;- not completely sure as to whether you could get away with doing
;;- this only for the mov* insns, or if you'd have to do it for all
;;- named insns.
;;- 	2) Add code to the mov{[ds]f,[ds]i} instructions to handle
;;- moving between fpa regs and 68881 regs.

;;- Since the fpa is more powerful than the 68881 and also has more
;;- registers, and since I think the reultant md would be medium ugly
;;- (lot's of duplicate code, ugly constraint strings), I elected not
;;- to do this change.

;;- Another reason why someone *might* want to do the change is to
;;- control which register classes are accessed in a slightly cleaner
;;- way than I have.  See the blurb on CONDITIONAL_REGISTER_USAGE in
;;- the internals manual.

;;- Yet another reason why someone might want to do this change is to
;;- allow use of some of the 68881 insns which have no equivalent on
;;- the fpa.  The sqrt instruction comes fairly quickly to mind.

;;- If this is ever done, don't forget to change tm-sun3.h so that
;;- it *will* define __HAVE_68881__ when the FPA is in use.

;;-		Condition code hack

;;- When a floating point compare is done in the fpa, the resulting
;;- condition codes are left in the fpastatus register.  The values in
;;- this register must be moved into the 68000 cc register before any
;;- jump is executed.  Once this has been done, regular jump
;;- instructions are fine (ie. floating point jumps are not necessary.
;;- They are only done if the cc is in the 68881).

;;- The instructions that move the fpastatus register to the 68000
;;- register clobber a data register (the move cannot be done direct).
;;- These instructions might be bundled either with the compare
;;- instruction, or the branch instruction.  If we were using both the
;;- fpa and the 68881 together, we would wish to only mark the
;;- register clobbered if we were doing the compare in the fpa, but I
;;- think that that decision (whether to clobber the register or not)
;;- must be done before register allocation (makes sense) and hence we
;;- can't know if the floating point compare will be done in the fpa
;;- or the fp.  So whenever we are asked for code that uses the fpa,
;;- we will mark a data register as clobbered.  This is reasonable, as
;;- almost all floating point compare operations done with fpa code
;;- enabled will be done in the fpa.  It's even more reasonable since
;;- we decided to make the 68881 and the fpa mutually exclusive.

;;- We place to code to move the fpastatus register inside of a
;;- define_expand so that we can do it conditionally based on whether
;;- we are tagetting an fpa or not.

;;- This still leaves us with the question of where we wish to put the
;;- code to move the fpastatus reg.  If we put it in the compare
;;- instruction, we can restrict the clobbering of the register to
;;- floating point compares, but we can't take advantage of floating
;;- point subtracts & etc. that alter the fpastatus register.  If we
;;- put it in the branch instruction, all branches compiled with fpa
;;- code enabled will clobber a data register, but we will be able to
;;- take advantage of fpa subtracts.  This balance favors putting the
;;- code in with the compare instruction.

;;- Note that if some enterprising hacker should decide to switch
;;- this, he'll need to modify the code in NOTICE_UPDATE_CC.

;;-		Usage of the top 16 fpa registers

;;- The only locations which we may transfer fpa registers 16-31 from
;;- or to are the fpa registers 0-15.  (68000 registers and memory
;;- locations are impossible).  This causes problems in gcc, which
;;- assumes that mov?? instructions require no additional registers
;;- (see section 11.7) and since floating point moves *must* be
;;- supported into general registers (see section 12.3 under
;;- HARD_REGNO_OK_FOR_MODE_P) from anywhere.

;;- My solution was to reserve fpa0 for moves into or out of these top
;;- 16 registers and to disparage the choice to reload into or out of
;;- these registers as much as I could.  That alternative is always
;;- last in the list, so it will not be used unless all else fails.  I
;;- will note that according to my current information, sun's compiler
;;- doesn't use these top 16 registers at all.

;;- There is another possible way to do it.  I *believe* that if you
;;- make absolutely sure that the code will not be exectued in the
;;- reload pass, you can support the mov?? names with define_expands
;;- which require new registers.  This may be possible by the
;;- appropriate juggling of constraints.  I may come back to this later.

;;- 		Usage of constant RAM

;;- This has been handled correctly (I believe) but the way I've done
;;- it could use a little explanation.  The constant RAM can only be
;;- accessed when the instruction is in "command register" mode.
;;- "command register" mode means that no accessing of memory or the
;;- 68000 registers is being done.  This can be expressed easily in
;;- constraints, so generally the mode of the instruction is
;;- determined by a branch off of which_alternative.  In outputing
;;- instructions, a 'w' means to output an access to the constant ram
;;- (if the arg is CONST_DOUBLE and is one of the available
;;- constants), and 'x' means to output a register pair (if the arg is
;;- a 68000 register) and a 'y' is the combination of the above two
;;- processies.  You use a 'y' in two operand DF instructions where you
;;- *know* the other operand is an fpa register, you use an 'x' in DF
;;- instructions where the arg might be a 68000 register and the
;;- instruction is *not* in "command register" mode, and you use a 'w'
;;- in two situations: 1) The instruction *is* in command register
;;- mode (and hence won't be accessing 68000 registers), or 2) The
;;- instruction is a two operand SF instruction where you know the
;;- other operand is an fpa register.

;;-		Optimization issues

;;- I actually think that I've included all of the fpa instructions
;;- that should be included.  Note that if someone is interested in
;;- doing serious floating point work on the sun fpa, I would advise
;;- the use of the "asm" instruction in gcc to allow you to use the
;;- sin, cos, and exponential functions on the fpa board.

;;- END FPA Explanation Section.


;;- Some of these insn's are composites of several m68000 op codes.
;;- The assembler (or final @@??) insures that the appropriate one is
;;- selected.

(define_insn ""
  [(set (match_operand:DF 0 "push_operand" "=m")
	(match_operand:DF 1 "general_operand" "ro<>fyF"))]
  ""
  "*
{
  if (FP_REG_P (operands[1]))
    return \"fmove%.d %f1,%0\";
  if (FPA_REG_P (operands[1]))
    return \"fpmove%.d %1, %x0\";
  return output_move_double (operands);
}")

(define_insn ""
  [(set (match_operand:DI 0 "push_operand" "=m")
	(match_operand:DI 1 "general_operand" "ro<>Fy"))]
  ""
  "*
{
  return output_move_double (operands);
}")

;; Put tstsi first among test insns so it matches a CONST_INT operand.

(define_insn "tstsi"
  [(set (cc0)
	(match_operand:SI 0 "general_operand" "rm"))]
  ""
  "*
{
#ifdef ISI_OV
  /* ISI's assembler fails to handle tstl a0.  */
  if (! ADDRESS_REG_P (operands[0]))
#else
  if (TARGET_68020 || ! ADDRESS_REG_P (operands[0]))
#endif
    return \"tst%.l %0\";
  /* If you think that the 68020 does not support tstl a0,
     reread page B-167 of the 68020 manual more carefully.  */
  /* On an address reg, cmpw may replace cmpl.  */
#ifdef HPUX_ASM
  return \"cmp%.w %0,%#0\";
#else
  return \"cmp%.w %#0,%0\";
#endif
}")

(define_insn "tsthi"
  [(set (cc0)
	(match_operand:HI 0 "general_operand" "rm"))]
  ""
  "*
{
#ifdef ISI_OV
  if (! ADDRESS_REG_P (operands[0]))
#else
  if (TARGET_68020 || ! ADDRESS_REG_P (operands[0]))
#endif
    return \"tst%.w %0\";
#ifdef HPUX_ASM
  return \"cmp%.w %0,%#0\";
#else
  return \"cmp%.w %#0,%0\";
#endif
}")

(define_insn "tstqi"
  [(set (cc0)
	(match_operand:QI 0 "general_operand" "dm"))]
  ""
  "tst%.b %0")
  
(define_expand "tstsf"
  [(set (cc0)
	(match_operand:SF 0 "general_operand" ""))]
  "TARGET_68881 || TARGET_FPA"
  "
{
  if (TARGET_FPA)
    {
      emit_insn (gen_rtx (PARALLEL, VOIDmode,
		          gen_rtvec (2,
				     gen_rtx (SET, VOIDmode,
					      cc0_rtx, operands[0]),
				     gen_rtx (CLOBBER, VOIDmode,
					      gen_reg_rtx (SImode)))));
      DONE;
    }
}")

(define_insn ""
  [(set (cc0)
	(match_operand:SF 0 "general_operand" "xmdF"))
   (clobber (match_operand:SI 1 "general_operand" "d"))]
  "TARGET_FPA"
  "fptst%.s %x0\;fpmove fpastatus,%1\;movw %1,cc")

(define_insn ""
  [(set (cc0)
	(match_operand:SF 0 "general_operand" "fdm"))]
  "TARGET_68881"
  "*
{
  cc_status.flags = CC_IN_68881;
  if (FP_REG_P (operands[0]))
    return \"ftst%.x %0\";
  return \"ftst%.s %0\";
}")

(define_expand "tstdf"
  [(set (cc0)
	(match_operand:DF 0 "general_operand" ""))]
  "TARGET_68881 || TARGET_FPA"
  "
{
  if (TARGET_FPA)
    {
      emit_insn (gen_rtx (PARALLEL, VOIDmode,
			  gen_rtvec (2, gen_rtx (SET, VOIDmode,
						 cc0_rtx, operands[0]),
				     gen_rtx (CLOBBER, VOIDmode,
					      gen_reg_rtx (SImode)))));
      DONE;
    }
}")

(define_insn ""
  [(set (cc0)
	(match_operand:DF 0 "general_operand" "xrmF"))
   (clobber (match_operand:SI 1 "general_operand" "d"))]
  "TARGET_FPA"
  "fptst%.d %x0\;fpmove fpastatus,%1\;movw %1,cc")

(define_insn ""
  [(set (cc0)
	(match_operand:DF 0 "general_operand" "fm"))]
  "TARGET_68881"
  "*
{
  cc_status.flags = CC_IN_68881;
  if (FP_REG_P (operands[0]))
    return \"ftst%.x %0\";
  return \"ftst%.d %0\";
}")

;; compare instructions.

;; Put cmpsi first among compare insns so it matches two CONST_INT operands.

;; A composite of the cmp, cmpa, & cmpi m68000 op codes.
(define_insn "cmpsi"
  [(set (cc0)
	(compare (match_operand:SI 0 "general_operand" "rKs,mr,>")
		 (match_operand:SI 1 "general_operand" "mr,Ksr,>")))]
  ""
  "*
{
  if (GET_CODE (operands[0]) == MEM && GET_CODE (operands[1]) == MEM)
    return \"cmpm%.l %1,%0\";
  if (REG_P (operands[1])
      || (!REG_P (operands[0]) && GET_CODE (operands[0]) != MEM))
    { cc_status.flags |= CC_REVERSED;
#ifdef HPUX_ASM
      return \"cmp%.l %d1,%d0\";
#else
      return \"cmp%.l %d0,%d1\"; 
#endif
    }
#ifdef HPUX_ASM
  return \"cmp%.l %d0,%d1\";
#else
  return \"cmp%.l %d1,%d0\";
#endif
}")

(define_insn "cmphi"
  [(set (cc0)
	(compare (match_operand:HI 0 "general_operand" "rnm,d,n,m")
		 (match_operand:HI 1 "general_operand" "d,rnm,m,n")))]
  ""
  "*
{
  if (GET_CODE (operands[0]) == MEM && GET_CODE (operands[1]) == MEM)
    return \"cmpm%.w %1,%0\";
  if ((REG_P (operands[1]) && !ADDRESS_REG_P (operands[1]))
      || (!REG_P (operands[0]) && GET_CODE (operands[0]) != MEM))
    { cc_status.flags |= CC_REVERSED;
#ifdef HPUX_ASM
      return \"cmp%.w %d1,%d0\";
#else
      return \"cmp%.w %d0,%d1\"; 
#endif
    }
#ifdef HPUX_ASM
  return \"cmp%.w %d0,%d1\";
#else
  return \"cmp%.w %d1,%d0\";
#endif
}")

(define_insn "cmpqi"
  [(set (cc0)
	(compare (match_operand:QI 0 "general_operand" "dn,md,>")
		 (match_operand:QI 1 "general_operand" "dm,nd,>")))]
  ""
  "*
{
  if (GET_CODE (operands[0]) == MEM && GET_CODE (operands[1]) == MEM)
    return \"cmpm%.b %1,%0\";
  if (REG_P (operands[1])
      || (!REG_P (operands[0]) && GET_CODE (operands[0]) != MEM))
    { cc_status.flags |= CC_REVERSED;
#ifdef HPUX_ASM
      return \"cmp%.b %d1,%d0\";
#else
      return \"cmp%.b %d0,%d1\";
#endif