i386.md

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

;; GCC machine description for IA-32 and x86-64.
;; Copyright (C) 1988, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
;; 2001, 2002, 2003
;; Free Software Foundation, Inc.
;; Mostly by William Schelter.
;; x86_64 support added by Jan Hubicka
;;
;; 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 2, 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, 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.  */
;;
;; 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.
;;
;; Macro #define NOTICE_UPDATE_CC in file i386.h handles condition code
;; updates for most instructions.
;;
;; Macro REG_CLASS_FROM_LETTER in file i386.h defines the register
;; constraint letters.
;;
;; The special asm out single letter directives following a '%' are:
;; 'z' mov%z1 would be movl, movw, or movb depending on the mode of
;;     operands[1].
;; 'L' Print the opcode suffix for a 32-bit integer opcode.
;; 'W' Print the opcode suffix for a 16-bit integer opcode.
;; 'B' Print the opcode suffix for an 8-bit integer opcode.
;; 'Q' Print the opcode suffix for a 64-bit float opcode.
;; 'S' Print the opcode suffix for a 32-bit float opcode.
;; 'T' Print the opcode suffix for an 80-bit extended real XFmode float opcode.
;; 'J' Print the appropriate jump operand.
;;
;; 'b' Print the QImode name of the register for the indicated operand.
;;     %b0 would print %al if operands[0] is reg 0.
;; 'w' Likewise, print the HImode name of the register.
;; 'k' Likewise, print the SImode name of the register.
;; 'h' Print the QImode name for a "high" register, either ah, bh, ch or dh.
;; 'y' Print "st(0)" instead of "st" as a register.

;; UNSPEC usage:

(define_constants
  [; Relocation specifiers
   (UNSPEC_GOT			0)
   (UNSPEC_GOTOFF		1)
   (UNSPEC_GOTPCREL		2)
   (UNSPEC_GOTTPOFF		3)
   (UNSPEC_TPOFF		4)
   (UNSPEC_NTPOFF		5)
   (UNSPEC_DTPOFF		6)
   (UNSPEC_GOTNTPOFF		7)
   (UNSPEC_INDNTPOFF		8)

   ; Prologue support
   (UNSPEC_STACK_PROBE		10)
   (UNSPEC_STACK_ALLOC		11)
   (UNSPEC_SET_GOT		12)
   (UNSPEC_SSE_PROLOGUE_SAVE	13)

   ; TLS support
   (UNSPEC_TP			15)
   (UNSPEC_TLS_GD		16)
   (UNSPEC_TLS_LD_BASE		17)

   ; Other random patterns
   (UNSPEC_SCAS			20)
   (UNSPEC_SIN			21)
   (UNSPEC_COS			22)
   (UNSPEC_BSF			23)
   (UNSPEC_FNSTSW		24)
   (UNSPEC_SAHF			25)
   (UNSPEC_FSTCW		26)
   (UNSPEC_ADD_CARRY		27)
   (UNSPEC_FLDCW		28)

   ; For SSE/MMX support:
   (UNSPEC_FIX			30)
   (UNSPEC_MASKMOV		32)
   (UNSPEC_MOVMSK		33)
   (UNSPEC_MOVNT		34)
   (UNSPEC_MOVA			38)
   (UNSPEC_MOVU			39)
   (UNSPEC_SHUFFLE		41)
   (UNSPEC_RCP			42)
   (UNSPEC_RSQRT		43)
   (UNSPEC_SFENCE		44)
   (UNSPEC_NOP			45)	; prevents combiner cleverness
   (UNSPEC_PAVGUSB		49)
   (UNSPEC_PFRCP		50)
   (UNSPEC_PFRCPIT1		51)
   (UNSPEC_PFRCPIT2		52)
   (UNSPEC_PFRSQRT		53)
   (UNSPEC_PFRSQIT1		54)
   (UNSPEC_PSHUFLW		55)
   (UNSPEC_PSHUFHW		56)
   (UNSPEC_MFENCE		59)
   (UNSPEC_LFENCE		60)
   (UNSPEC_PSADBW		61)
  ])

(define_constants
  [(UNSPECV_BLOCKAGE		0)
   (UNSPECV_EH_RETURN		13)
   (UNSPECV_EMMS		31)
   (UNSPECV_LDMXCSR		37)
   (UNSPECV_STMXCSR		40)
   (UNSPECV_FEMMS		46)
   (UNSPECV_CLFLUSH		57)
  ])

;; Insns whose names begin with "x86_" are emitted by gen_FOO calls
;; from i386.c.

;; In C guard expressions, put expressions which may be compile-time
;; constants first.  This allows for better optimization.  For
;; example, write "TARGET_64BIT && reload_completed", not
;; "reload_completed && TARGET_64BIT".


;; Processor type.  This attribute must exactly match the processor_type
;; enumeration in i386.h.
(define_attr "cpu" "i386,i486,pentium,pentiumpro,k6,athlon,pentium4"
  (const (symbol_ref "ix86_cpu")))

;; A basic instruction type.  Refinements due to arguments to be
;; provided in other attributes.
(define_attr "type"
  "other,multi,
   alu,alu1,negnot,imov,imovx,lea,
   incdec,ishift,ishift1,rotate,rotate1,imul,idiv,
   icmp,test,ibr,setcc,icmov,
   push,pop,call,callv,
   str,cld,
   fmov,fop,fsgn,fmul,fdiv,fpspc,fcmov,fcmp,fxch,fistp,
   sselog,sseiadd,sseishft,sseimul,
   sse,ssemov,sseadd,ssemul,ssecmp,ssecvt,ssediv,
   mmx,mmxmov,mmxadd,mmxmul,mmxcmp,mmxcvt,mmxshft"
  (const_string "other"))

;; Main data type used by the insn
(define_attr "mode"
  "unknown,none,QI,HI,SI,DI,unknownfp,SF,DF,XF,TI,V4SF,V2DF,V2SF"
  (const_string "unknown"))

;; The CPU unit operations uses.
(define_attr "unit" "integer,i387,sse,mmx,unknown"
  (cond [(eq_attr "type" "fmov,fop,fsgn,fmul,fdiv,fpspc,fcmov,fcmp,fxch,fistp")
	   (const_string "i387")
	 (eq_attr "type" "sselog,sseiadd,sseishft,sseimul,
			  sse,ssemov,sseadd,ssemul,ssecmp,ssecvt,ssediv")
	   (const_string "sse")
	 (eq_attr "type" "mmx,mmxmov,mmxadd,mmxmul,mmxcmp,mmxcvt,mmxshft")
	   (const_string "mmx")
	 (eq_attr "type" "other")
	   (const_string "unknown")]
	 (const_string "integer")))

;; The (bounding maximum) length of an instruction immediate.
(define_attr "length_immediate" ""
  (cond [(eq_attr "type" "incdec,setcc,icmov,str,cld,lea,other,multi,idiv")
	   (const_int 0)
	 (eq_attr "unit" "i387,sse,mmx")
	   (const_int 0)
	 (eq_attr "type" "alu,alu1,negnot,imovx,ishift,rotate,ishift1,rotate1,
			  imul,icmp,push,pop")
	   (symbol_ref "ix86_attr_length_immediate_default(insn,1)")
	 (eq_attr "type" "imov,test")
	   (symbol_ref "ix86_attr_length_immediate_default(insn,0)")
	 (eq_attr "type" "call")
	   (if_then_else (match_operand 0 "constant_call_address_operand" "")
	     (const_int 4)
	     (const_int 0))
	 (eq_attr "type" "callv")
	   (if_then_else (match_operand 1 "constant_call_address_operand" "")
	     (const_int 4)
	     (const_int 0))
	 ;; We don't know the size before shorten_branches.  Expect
	 ;; the instruction to fit for better scheduling.
	 (eq_attr "type" "ibr")
	   (const_int 1)
	 ]
	 (symbol_ref "/* Update immediate_length and other attributes! */
		      abort(),1")))

;; The (bounding maximum) length of an instruction address.
(define_attr "length_address" ""
  (cond [(eq_attr "type" "str,cld,other,multi,fxch")
	   (const_int 0)
	 (and (eq_attr "type" "call")
	      (match_operand 0 "constant_call_address_operand" ""))
	     (const_int 0)
	 (and (eq_attr "type" "callv")
	      (match_operand 1 "constant_call_address_operand" ""))
	     (const_int 0)
	 ]
	 (symbol_ref "ix86_attr_length_address_default (insn)")))

;; Set when length prefix is used.
(define_attr "prefix_data16" ""
  (if_then_else (ior (eq_attr "mode" "HI")
		     (and (eq_attr "unit" "sse") (eq_attr "mode" "V2DF")))
    (const_int 1)
    (const_int 0)))

;; Set when string REP prefix is used.
(define_attr "prefix_rep" "" 
  (if_then_else (and (eq_attr "unit" "sse") (eq_attr "mode" "SF,DF"))
    (const_int 1)
    (const_int 0)))

;; Set when 0f opcode prefix is used.
(define_attr "prefix_0f" ""
  (if_then_else 
    (eq_attr "type" 
             "imovx,setcc,icmov,
              sselog,sseiadd,sseishft,sseimul,
              sse,ssemov,sseadd,ssemul,ssecmp,ssecvt,ssediv,
              mmx,mmxmov,mmxadd,mmxmul,mmxcmp,mmxcvt,mmxshft")
    (const_int 1)
    (const_int 0)))

;; Set when modrm byte is used.
(define_attr "modrm" ""
  (cond [(eq_attr "type" "str,cld")
	   (const_int 0)
	 (eq_attr "unit" "i387")
	   (const_int 0)
         (and (eq_attr "type" "incdec")
	      (ior (match_operand:SI 1 "register_operand" "")
		   (match_operand:HI 1 "register_operand" "")))
	   (const_int 0)
	 (and (eq_attr "type" "push")
	      (not (match_operand 1 "memory_operand" "")))
	   (const_int 0)
	 (and (eq_attr "type" "pop")
	      (not (match_operand 0 "memory_operand" "")))
	   (const_int 0)
	 (and (eq_attr "type" "imov")
	      (and (match_operand 0 "register_operand" "")
	           (match_operand 1 "immediate_operand" "")))
	   (const_int 0)
	 (and (eq_attr "type" "call")
	      (match_operand 0 "constant_call_address_operand" ""))
	     (const_int 0)
	 (and (eq_attr "type" "callv")
	      (match_operand 1 "constant_call_address_operand" ""))
	     (const_int 0)
	 ]
	 (const_int 1)))

;; The (bounding maximum) length of an instruction in bytes.
;; ??? fistp is in fact fldcw/fistp/fldcw sequence.  Later we may want
;; to split it and compute proper length as for other insns.
(define_attr "length" ""
  (cond [(eq_attr "type" "other,multi,fistp")
	   (const_int 16)
	 (eq_attr "type" "fcmp")
	   (const_int 4)
	 (eq_attr "unit" "i387")
	   (plus (const_int 2)
		 (plus (attr "prefix_data16")
		       (attr "length_address")))]
	 (plus (plus (attr "modrm")
		     (plus (attr "prefix_0f")
			   (const_int 1)))
	       (plus (attr "prefix_rep")
		     (plus (attr "prefix_data16")
			   (plus (attr "length_immediate")
				 (attr "length_address")))))))

;; The `memory' attribute is `none' if no memory is referenced, `load' or
;; `store' if there is a simple memory reference therein, or `unknown'
;; if the instruction is complex.

(define_attr "memory" "none,load,store,both,unknown"
  (cond [(eq_attr "type" "other,multi,str")
	   (const_string "unknown")
	 (eq_attr "type" "lea,fcmov,fpspc,cld")
	   (const_string "none")
	 (eq_attr "type" "fistp")
	   (const_string "both")
	 (eq_attr "type" "push")
	   (if_then_else (match_operand 1 "memory_operand" "")
	     (const_string "both")
	     (const_string "store"))
	 (eq_attr "type" "pop,setcc")
	   (if_then_else (match_operand 0 "memory_operand" "")
	     (const_string "both")
	     (const_string "load"))
	 (eq_attr "type" "icmp,test,ssecmp,mmxcmp,fcmp")
	   (if_then_else (ior (match_operand 0 "memory_operand" "")
			      (match_operand 1 "memory_operand" ""))
	     (const_string "load")
	     (const_string "none"))
	 (eq_attr "type" "ibr")
	   (if_then_else (match_operand 0 "memory_operand" "")
	     (const_string "load")
	     (const_string "none"))
	 (eq_attr "type" "call")
	   (if_then_else (match_operand 0 "constant_call_address_operand" "")
	     (const_string "none")
	     (const_string "load"))
	 (eq_attr "type" "callv")
	   (if_then_else (match_operand 1 "constant_call_address_operand" "")
	     (const_string "none")
	     (const_string "load"))
	 (and (eq_attr "type" "alu1,negnot")
	      (match_operand 1 "memory_operand" ""))
	   (const_string "both")
	 (and (match_operand 0 "memory_operand" "")
	      (match_operand 1 "memory_operand" ""))
	   (const_string "both")
	 (match_operand 0 "memory_operand" "")
	   (const_string "store")
	 (match_operand 1 "memory_operand" "")
	   (const_string "load")
	 (and (eq_attr "type"
		 "!alu1,negnot,
		   imov,imovx,icmp,test,
		   fmov,fcmp,fsgn,
		   sse,ssemov,ssecmp,ssecvt,
		   mmx,mmxmov,mmxcmp,mmxcvt")
	      (match_operand 2 "memory_operand" ""))
	   (const_string "load")
	 (and (eq_attr "type" "icmov")
	      (match_operand 3 "memory_operand" ""))
	   (const_string "load")
	]
	(const_string "none")))

;; Indicates if an instruction has both an immediate and a displacement.

(define_attr "imm_disp" "false,true,unknown"
  (cond [(eq_attr "type" "other,multi")
	   (const_string "unknown")
	 (and (eq_attr "type" "icmp,test,imov,alu1,ishift1,rotate1")
	      (and (match_operand 0 "memory_displacement_operand" "")
		   (match_operand 1 "immediate_operand" "")))
	   (const_string "true")
	 (and (eq_attr "type" "alu,ishift,rotate,imul,idiv")
	      (and (match_operand 0 "memory_displacement_operand" "")
		   (match_operand 2 "immediate_operand" "")))
	   (const_string "true")
	]
	(const_string "false")))

;; Indicates if an FP operation has an integer source.

(define_attr "fp_int_src" "false,true"
  (const_string "false"))

;; Describe a user's asm statement.
(define_asm_attributes
  [(set_attr "length" "128")
   (set_attr "type" "multi")])

(include "pentium.md")
(include "ppro.md")
(include "k6.md")
(include "athlon.md")

;; Compare instructions.

;; All compare insns have expanders that save the operands away without
;; actually generating RTL.  The bCOND or sCOND (emitted immediately
;; after the cmp) will actually emit the cmpM.

(define_expand "cmpdi"
  [(set (reg:CC 17)
	(compare:CC (match_operand:DI 0 "nonimmediate_operand" "")
		    (match_operand:DI 1 "x86_64_general_operand" "")))]
  ""
{
  if (GET_CODE (operands[0]) == MEM && GET_CODE (operands[1]) == MEM)
    operands[0] = force_reg (DImode, operands[0]);
  ix86_compare_op0 = operands[0];
  ix86_compare_op1 = operands[1];
  DONE;
})

(define_expand "cmpsi"
  [(set (reg:CC 17)
	(compare:CC (match_operand:SI 0 "cmpsi_operand" "")
		    (match_operand:SI 1 "general_operand" "")))]
  ""
{
  if (GET_CODE (operands[0]) == MEM && GET_CODE (operands[1]) == MEM)
    operands[0] = force_reg (SImode, operands[0]);
  ix86_compare_op0 = operands[0];
  ix86_compare_op1 = operands[1];
  DONE;
})

(define_expand "cmphi"
  [(set (reg:CC 17)
	(compare:CC (match_operand:HI 0 "nonimmediate_operand" "")
		    (match_operand:HI 1 "general_operand" "")))]
  ""