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[smlnj] View of /sml/trunk/src/MLRISC/x86/omit-frameptr/x86omit-frameptr.sml
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View of /sml/trunk/src/MLRISC/x86/omit-frameptr/x86omit-frameptr.sml

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Revision 1003 - (download) (annotate)
Fri Dec 7 02:45:32 2001 UTC (18 years, 1 month ago) by george
File size: 14435 byte(s)
Changed the representation of instructions from being fully abstract
to being partially concrete. That is to say:

	type instruction

	type instr				(* machine instruction *)

	datatype instruction =
	    LIVE of {regs: C.cellset, spilled: C.cellset}
          | KILL of {regs: C.cellset, spilled: C.cellset}
          | COPYXXX of {k: CB.cellkind, dst: CB.cell list, src: CB.cell list}
          | ANNOTATION of {i: instruction, a: Annotations.annotation}
          | INSTR of instr

This makes the handling of certain special instructions that appear on
all architectures easier and uniform.

LIVE and KILL say that a list of registers are live or killed at the
program point where they appear. No spill code is generated when an
element of the 'regs' field is spilled, but the register is moved to
the 'spilled' (which is present, more for debugging than anything else).

LIVE replaces the (now deprecated) DEFFREG instruction on the alpha.
We used to generate:

	f1 := f2 + f3

but now generate:

	f1 := f2 + f3
	LIVE {regs=[f1,f2,f3], spilled=[]}

Furthermore, the DEFFREG (hack) required that all floating point instruction
use all registers mentioned in the instruction. Therefore f1 := f2 + f3,
defines f1 and uses [f1,f2,f3]! This hack is no longer required resulting
in a cleaner alpha implementation. (Hopefully, intel will not get rid of
this architecture).

COPYXXX is intended to replace the parallel COPY and FCOPY  available on
all the architectures. This will result in further simplification of the
register allocator that must be aware of them for coalescing purposes, and
will also simplify certain aspects of the machine description that provides
callbacks related to parallel copies.

ANNOTATION should be obvious, and now INSTR represents the honest to God
machine instruction set!

The <arch>/instructions/<arch>Instr.sml files define certain utility
functions for making porting easier -- essentially converting upper case
to lower case. All machine instructions (of type instr) are in upper case,
and the lower case form generates an MLRISC instruction. For example on
the alpha we have:

  datatype instr =
     LDA of {r:cell, b:cell, d:operand}
   | ...

  val lda : {r:cell, b:cell, d:operand} -> instruction

where lda is just (INSTR o LDA), etc.
(* replaces uses and definitions of a virtual frame pointer (vfp) with the appropriate
 * operation on the stack pointer. 
 * Invariant: fp = sp + delta &&  stack grows from high to low 	&& fp >= sp
 * Assumptions: At the entry node fp = sp + idelta
 * The tricky business is to recognize that things that look like register may
 * really be memory registers.
functor X86OmitFramePointer (
    structure I : X86INSTR 
    structure CFG : CONTROL_FLOW_GRAPH where I = I
    structure MemRegs : MEMORY_REGISTERS where I=I
    val memRegBase : CellsBasis.cell option): OMIT_FRAME_POINTER = 
  structure CFG = CFG
  structure I = I
  structure C = I.C
  structure CB = CellsBasis
  structure HT = IntHashTable
  val sp = C.esp

  val dumpCfg = MLRiscControl.getFlag "dump-cfg-after-omit-frame-pointer"

  fun error msg = MLRiscErrorMsg.error("X86OmitFramePointer", msg)

  fun omitframeptr{vfp:CB.cell, idelta:Int32.int option, cfg as Graph.GRAPH graph} = let

    (* rewrite a list of instructions where the gap between fp and sp is delta *)
    fun rewrite(instrs, idelta) = let

      (* What kind of register? *)
      datatype which = SP | FP | OTHER
      fun isSp cell = CB.sameColor(cell, sp)
      fun isVfp cell = CB.sameColor(cell, vfp)
      fun which(cell) = if isSp(cell) then SP else if isVfp(cell) then FP else OTHER
      fun either(cell) = isSp(cell) orelse isVfp(cell) 

      (* Has the instruction been rewritten? *)
      val changedFlag = ref false		

       * rewrite a single instruction assuming gap (fp=sp+delta) 
       * returns NONE is instruction is deleted and SOME(instruction) otherwise.

      fun doInstr(instr, delta:Int32.int option) = let
	(* if a delta exists then add to it, 
	 * otherwise maintain that there is no delta
	fun addToDelta i = 
	  (case delta 
	   of SOME d => SOME(i+d)
	    | NONE => NONE

	fun incOffset(i) = 
	  (case delta
	   of NONE => error "incOffset"
	    | SOME k => k+i

	fun incDisp(I.Immed i) = I.Immed(incOffset(i))
	  | incDisp _ = error "incDisp"	(* CONSTANTS? *)

	fun operand(opnd as I.Displace{base, disp, mem}) = 
	    if isVfp base then 
	      (changedFlag := true;
	       I.Displace{base=sp, mem=mem, disp=incDisp(disp)})
	    else opnd
	  | operand(opnd as I.Indexed{base, index, scale, disp, mem}) = 
	    if isVfp index then 
	      error "operand: frame pointer used in index"
	    else (case base
	      of NONE => opnd
	       | SOME b => 
		 if isVfp b then 
		    (changedFlag := true;
		     I.Indexed{base=SOME(sp), index=index, scale=scale, mem=mem, 
		 else opnd
	  | operand(opnd as I.MemReg _) = 
	      operand(MemRegs.memReg{reg=opnd, base=Option.valOf memRegBase})
	  | operand(opnd as I.FDirect _) = 
	      operand(MemRegs.memReg{reg=opnd, base=Option.valOf memRegBase})
	  | operand(opnd) = opnd

	fun annotate(i, k:Int32.int option) = let
	  val instr = 
	    if !changedFlag then 
	       (changedFlag := false;
		case k 
		of NONE => i
		 | SOME d => 
		   if d <> 0 then let
		      val cmt = "offset adjusted to " ^ Int32.toString d
		      val ann = #create MLRiscAnnotations.COMMENT cmt
		    in I.ANNOTATION{i=i, a=ann}
		  else i
	    else i
	in (SOME(instr),k)

	fun unchanged(i:I.instr) = annotate(I.INSTR i, delta)  
	fun changedto(i, k) = annotate(I.INSTR i, k)

	fun compare(test, lsrc, rsrc) = unchanged(test{lsrc=operand(lsrc), rsrc=operand(rsrc)})
	fun float(oper, opnd) = unchanged(oper(operand(opnd)))

	fun doX86Instr (instr: I.instr) =
	 (case instr
	  of I.JMP(opnd,labs) => unchanged(I.JMP(operand opnd, labs))
	   | I.JCC{cond:I.cond, opnd:I.operand} => 
	      unchanged(I.JCC{cond=cond, opnd=operand(opnd)})
	   | I.CALL{opnd, defs, uses, cutsTo, mem, return, pops=0} => 
	      unchanged(I.CALL{opnd=operand(opnd), defs=defs, uses=uses,
			       cutsTo=cutsTo, mem=mem, pops=0,
	   | I.CALL{opnd, defs, uses, cutsTo, mem, return, pops} =>
	     changedto(I.CALL{opnd=operand(opnd), defs=defs, uses=uses,
			      cutsTo=cutsTo, mem=mem, pops=pops,
	   | I.ENTER{src1=I.Immed i1, src2=I.Immed i2} => changedto(instr,  addToDelta(i1 + i2*4))
	   | I.LEAVE => (SOME(I.INSTR instr), NONE)
	   | I.RET opnd => (SOME(I.INSTR instr), NONE)
	   | I.MOVE{mvOp:I.move, src=I.Direct s, dst=I.Direct d} =>
	     (case (which d, which s)
	      of (FP, SP) => (NONE, SOME 0)
	       | (SP, FP) => (case delta
		   of NONE => error "MOVE: (SP, FP)"
		    | SOME 0 => (NONE, SOME 0)
		    | SOME n => let 
			 val addr = I.Displace{base=sp, disp=I.Immed(n), mem=I.Region.stack}
			 (SOME(I.lea{r32=sp, addr=addr}), SOME 0)
	       | (OTHER, OTHER) => unchanged(instr)
	       | (FP, FP) => (NONE, delta)
	       | (SP, SP) => (NONE, delta)
	       | (FP, _) => error "MOVE: to FP"
	       | (SP, _) => error "MOVE: to SP"
	       | (OTHER, SP) => unchanged(instr)
	       | (OTHER, FP) => error "MOVE: FP to OTHER"	(* d:=sp+delta; lazy!*)
	   | I.MOVE{mvOp, src, dst as I.Direct d} =>
	       if either(d) then error "MOVE: assignment to FP/SP"
	       else unchanged(I.MOVE{mvOp=mvOp, src=operand(src), dst=dst})
	   | I.MOVE{mvOp, src, dst} => 
	       unchanged(I.MOVE{mvOp=mvOp, src=operand(src), dst=operand(dst)})
	   | I.LEA{r32:CB.cell, addr as I.Displace{base, disp=I.Immed d, mem}} => 
	     (case (which r32, which base) 
	      of (SP, SP) => 
		   (* assumes stack grows from high to low. 
		    * if sp is incremented by a positive delta, then the gap is
		    * reduced by delta-d;
		    * if sp is decremented, the the gap is increased and d is negative.
		   changedto(instr, addToDelta(~d))
	       | (SP, FP) => 
		   (*    sp = fp + d 
		    * or sp = sp + delta + d
		   changedto(I.LEA{r32=r32, addr=operand(addr)}, SOME(incOffset(d)))
	       | (FP, FP) => 
		   (* fp = fp + d
		    * if d is positive, then the gap is increased to delta+d,
		    * if d is negative, then the gap is reduced.
		   (NONE, SOME(incOffset(d)))
	       | (FP, SP) => (NONE, addToDelta(d))
	       | (SP, OTHER) => error "LEA: sp changed by non-immed"
	       | (FP, OTHER) => error "LEA: fp changed by non-immed"
	       | _ => unchanged(instr)
	   | I.LEA{r32, addr} => 
	     if either(r32) then error "LEA: SP/FP changed by non-immed"
	     else unchanged(I.LEA{r32=r32, addr=operand(addr)})
	   | I.CMPL{lsrc: I.operand, rsrc: I.operand} => compare(I.CMPL, lsrc, rsrc)
	   | I.CMPW{lsrc: I.operand, rsrc: I.operand} => compare(I.CMPW, lsrc, rsrc)
	   | I.CMPB{lsrc: I.operand, rsrc: I.operand} => compare(I.CMPB, lsrc, rsrc)
	   | I.TESTL{lsrc: I.operand, rsrc: I.operand} => compare(I.TESTL, lsrc, rsrc)
	   | I.TESTW{lsrc: I.operand, rsrc: I.operand} => compare(I.TESTW, lsrc, rsrc)
	   | I.TESTB{lsrc: I.operand, rsrc: I.operand} => compare(I.TESTB, lsrc, rsrc)
	   | I.BITOP{bitOp:I.bitOp, lsrc: I.operand, rsrc: I.operand} =>
	      unchanged(I.BITOP{bitOp=bitOp, lsrc=operand(lsrc), rsrc=operand(rsrc)})
	   | I.BINARY{binOp=I.ADDL, src=I.Immed(k), dst=I.Direct(d)} => 
	     (case which d
	      of SP => changedto(instr, addToDelta(~k))
	       | FP => (NONE, SOME(incOffset(k)))
	       | OTHER => unchanged(instr)
	   | I.BINARY{binOp=I.SUBL, src=I.Immed(k), dst=I.Direct(d)} => 
	     (case which d
	      of SP => changedto(instr, addToDelta(k))
	       | FP => (NONE, SOME(incOffset(~k)))
	       | OTHER => unchanged(instr)
	   | I.BINARY{binOp, dst as I.Direct(d), src} =>
	     if either(d) then error "binary: assignment to SP | FP"
	     else unchanged(I.BINARY{binOp=binOp, src=operand(src), dst=dst})
	   | I.BINARY{binOp, src, dst} =>
	      unchanged(I.BINARY{binOp=binOp, src=operand(src), dst=operand(dst)})
	   | I.CMPXCHG{lock:bool, sz:I.isize, src:I.operand, dst:I.operand} =>
	      unchanged(I.CMPXCHG{lock=lock, sz=sz, src=operand(src), dst=operand(dst)})
	   | I.MULTDIV{multDivOp:I.multDivOp, src:I.operand} =>
	      unchanged(I.MULTDIV{multDivOp=multDivOp, src=operand(src)})
	   | I.MUL3{dst:CB.cell, src2:Int32.int, src1:I.operand} => 
	     if either(dst) then error "MUL3: assignment to FP/SP"
	     else unchanged(I.MUL3{dst=dst, src2=src2, src1=operand(src1)})
	   | I.UNARY{unOp=I.INCL, opnd as I.Direct(r)} =>
	     (case (which r)
	      of SP => changedto(instr, addToDelta(~1))
	       | FP => (NONE, SOME(incOffset(1)))
	       | OTHER => unchanged(I.UNARY{unOp=I.INCL, opnd=opnd})
	   | I.UNARY{unOp=I.DECL, opnd as I.Direct(r)} => 
	     (case (which r)
	      of SP => changedto(instr, addToDelta(1))
	       | FP => (NONE, SOME(incOffset(~1)))
	       | OTHER => unchanged(I.UNARY{unOp=I.DECL, opnd=opnd})
	   | I.UNARY{unOp, opnd} => unchanged(I.UNARY{unOp=unOp, opnd=operand(opnd)})
	   | I.SET{cond:I.cond, opnd:I.operand} => 
	       unchanged(I.SET{cond=cond, opnd=operand(opnd)})
	   | I.CMOV{cond:I.cond, src as I.Direct(s), dst:CB.cell} =>
	       if either(s) orelse either(dst) then 
		 error "CMOV: FP/SP in conditional move"
	       else unchanged(I.CMOV{cond=cond, src=operand(src), dst=dst})
	   | I.PUSHL opnd => changedto(I.PUSHL(operand(opnd)), addToDelta(4))
	   | I.PUSHW opnd => changedto(I.PUSHW(operand(opnd)), addToDelta(2))
	   | I.PUSHB opnd => changedto(I.PUSHB(operand(opnd)), addToDelta(1))
	   | I.POP opnd => changedto(I.POP(operand(opnd)), addToDelta(~4))
	   | I.COPY{dst:CB.cell list, src:CB.cell list, tmp:I.operand option} => let
	      (* the situation where SP <- FP is somewhat complicated.
	       * The copy must be extracted, and a lea generated.
	       * Should it be before or after the parallel copy? Depends on if SP is used. 
	       * However, will such a thing ever exist in a parallel copy!?
	      fun okay(s, d, acc) = 
		(case (which s, which d) 
		 of (FP, SP) => true
		  | (SP, FP) => error "COPY:SP<-FP; lazy!"
		  | (SP, OTHER) => error "COPY:SP<-OTHER"
		  | (FP, OTHER) => error "COPY:FP<-OTHER"
		  | (OTHER, SP) => error "COPY:OTHER<-SP"
		  | (OTHER, FP)  => error "COPY:OTHER<-FP"
		  | _ => acc
	     in changedto(instr, if ListPair.foldl okay false (dst, src) then SOME 0 else delta)
	   | I.FBINARY{binOp:I.fbinOp, src:I.operand, dst:I.operand} =>
	      unchanged(I.FBINARY{binOp=binOp, src=operand(src), dst=operand(dst)})
	   | I.FIBINARY{binOp:I.fibinOp, src:I.operand} =>
	      unchanged(I.FIBINARY{binOp=binOp, src=operand(src)})
	   | I.FUCOM opnd => unchanged(I.FUCOM(operand opnd))
	   | I.FUCOMP opnd => unchanged(I.FUCOMP(operand (opnd)))
	   | I.FSTPL opnd => float(I.FSTPL, opnd)
	   | I.FSTPS opnd => float(I.FSTPS, opnd)
	   | I.FSTPT opnd  => float(I.FSTPT, opnd)
	   | I.FSTL opnd => float(I.FSTL, opnd)
	   | I.FSTS opnd => float(I.FSTS, opnd)
	   | I.FLDL opnd => float(I.FLDL, opnd)
	   | I.FLDS opnd => float(I.FLDS, opnd)
	   | I.FLDT opnd => float(I.FLDT, opnd)
	   | I.FILD opnd => float(I.FILD, opnd)
	   | I.FILDL opnd => float(I.FILDLL, opnd)
	   | I.FILDLL opnd => float(I.FILDLL, opnd)
	   | I.FENV{fenvOp:I.fenvOp, opnd:I.operand} =>
	       unchanged(I.FENV{fenvOp=fenvOp, opnd=operand(opnd)})
	   | I.FMOVE{fsize:I.fsize, src:I.operand, dst:I.operand} =>
	       unchanged(I.FMOVE{fsize=fsize, src=operand(src), dst=operand(dst)})
	   | I.FILOAD{isize:I.isize, ea:I.operand, dst:I.operand} =>
	       unchanged(I.FILOAD{isize=isize, ea=operand(ea), dst=operand(dst)})
	   | I.FBINOP{fsize, binOp, lsrc, rsrc, dst} =>
	       unchanged(I.FBINOP{fsize=fsize, binOp=binOp, lsrc=operand(lsrc), 
				  rsrc=operand(rsrc), dst=operand(dst)})
	   | I.FIBINOP{isize, binOp, lsrc, rsrc, dst} =>
	       unchanged(I.FIBINOP{isize=isize, binOp=binOp, lsrc=operand(lsrc), 
				  rsrc=operand(rsrc), dst=operand(dst)})
	   | I.FUNOP{fsize:I.fsize, unOp:I.funOp, src:I.operand, dst:I.operand} =>
	       unchanged(I.FUNOP{fsize=fsize, unOp=unOp, src=operand(src), 
	   | I.FCMP{fsize:I.fsize, lsrc:I.operand, rsrc:I.operand} =>
	       unchanged(I.FCMP{fsize=fsize, lsrc=operand(lsrc), rsrc=operand(rsrc)})
	   | _ => unchanged(instr)
	  case instr 
	  of I.ANNOTATION{i,a} => let
	       val (instr, delta) = doInstr(i, delta)
		case instr 
		of NONE => (NONE, delta)
		 | SOME(i) => annotate(I.ANNOTATION{i=i, a=a}, delta)
	   | I.INSTR instr => doX86Instr instr
	   | _ => error "doInstr"
      end (*doInstr*)

      (* rewrite instructions *)
      fun doInstrs([], instrs, delta) = (instrs, delta)
        | doInstrs(instr::rest, acc, delta) = let
            val (instr, delta2) = doInstr(instr, delta)
	    case instr
	    of NONE => doInstrs(rest, acc, delta2)
	     | SOME(i) => doInstrs(rest, i::acc, delta2)

    in doInstrs(instrs, [], idelta)
    end (* rewrite *)


    (* rewrite blocks using a depth first traversal of the blocks *)
    val info : {visited:bool, delta: Int32.int option} HT.hash_table = 
      HT.mkTable(32, General.Fail "X86OmitFramePtr: Not Found")
    val noInfo = {visited=false, delta=NONE}

    fun dfs (nid, delta) = let
      fun doSucc(delta) = 
	app (fn snid => dfs(snid, delta)) (#succ graph nid)
      val CFG.BLOCK{insns, kind, ...} = #node_info graph nid
      case kind
      of CFG.STOP => ()
       | CFG.START => doSucc(delta)
       | CFG.NORMAL => let
	   val {visited, delta=d} = Option.getOpt(HT.find info nid, noInfo)
	   fun sameDelta(NONE, NONE) = true
	     | sameDelta(SOME i1: Int32.int option, SOME i2) = i1 = i2
	   if visited then (if sameDelta(d, delta) then () else error "dfs")
	   else let
	       val (instrs, delta2) = rewrite(rev(!insns), delta)
	       insns := instrs;
	       HT.insert info (nid, {visited=true, delta=delta});

    val CB.CELL{col, ...} = vfp
     * check that virtual frame pointer is a pseudo register or
     * aliased to the stack pointer.
    case !col
     of CB.PSEUDO => app (fn nid => dfs(nid, idelta)) (#entries graph ())
      | _ => error "virtual frame pointer not a pseudo register"
    (* output cluster  *)
(*    if !dumpCfg then 
      PC.printCluster TextIO.stdOut "after omit frame pointer"  cl
      else () *)

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