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|
(* Stolen from John Reppy's Moby compiler:
*
* x86-leaf-opt.sml
*
* COPYRIGHT (c) 2001 Bell Labs, Lucent Technologies
*
* Optimization of leaf procedures for the IA32. We define a leaf procedure
* to be one that does not make calls and does not allocate any extra stack
* space (other than the usual linkage). We optimize by removing the saved
* frame-pointer and rewriting instructions that use the frame-pointer to
* ones that use the stack pointer.
*
* Eventually, we may support tail calls from leaf procedures.
*
*)
functor X86LeafOpt
(structure X86Instr : X86INSTR
structure FlowGraph : FLOWGRAPH where I = X86Instr
val isLeaf : FlowGraph.cluster -> bool
) : CLUSTER_OPTIMIZATION =
struct
structure F = FlowGraph
structure I = X86Instr
structure C = I.C
type flowgraph = F.cluster
val name = "X86LeafOpt"
(* is a register the frame pointer? *)
fun isFP reg = C.sameColor(reg, C.ebp)
(* is a register the stack pointer? *)
fun isSP reg = C.sameColor(reg, C.esp)
fun error msg = MLRiscErrorMsg.error("X86LeafOpt",msg)
fun err (blknum, msg) = error(concat[
"BLOCK ", Int.toString blknum, ": ", msg
])
fun optimize (F.CLUSTER cluster) = let
fun rewriteOpnd (opnd as I.Displace{base, disp, mem}) =
if (isFP base)
then (case disp
of I.Immed n =>
I.Displace{base = C.esp, disp = I.Immed(n-4), mem = mem}
| _ => error "unable to rewrite displacement operand"
(* end case *))
else opnd
| rewriteOpnd (opnd as I.Indexed{base=SOME r, index, scale, disp, mem}) =
if (isFP r)
then (case disp
of I.Immed n => I.Indexed{
base = SOME C.esp, index = index, scale = scale,
disp = I.Immed(n-4), mem = mem
}
| _ => error "unable to rewrite indexed operand"
(* end case *))
else opnd
| rewriteOpnd opnd = opnd
fun rewriteInsn insn = (case insn
of I.JMP(opnd, labs) => I.JMP(rewriteOpnd opnd, labs)
| I.JCC{cond, opnd} => I.JCC{cond = cond, opnd = rewriteOpnd opnd}
| I.CALL _ => error "unexpected call"
| I.MOVE{mvOp, src, dst} => I.MOVE{
mvOp = mvOp,
src = rewriteOpnd src,
dst = rewriteOpnd dst
}
| I.LEA{r32, addr} => I.LEA{r32 = r32, addr = rewriteOpnd addr}
| I.CMPL{lsrc, rsrc} =>
I.CMPL{lsrc = rewriteOpnd lsrc, rsrc = rewriteOpnd rsrc}
| I.CMPW{lsrc, rsrc} =>
I.CMPW{lsrc = rewriteOpnd lsrc, rsrc = rewriteOpnd rsrc}
| I.CMPB{lsrc, rsrc} =>
I.CMPB{lsrc = rewriteOpnd lsrc, rsrc = rewriteOpnd rsrc}
| I.TESTL{lsrc, rsrc} =>
I.TESTL{lsrc = rewriteOpnd lsrc, rsrc = rewriteOpnd rsrc}
| I.TESTW{lsrc, rsrc} =>
I.TESTW{lsrc = rewriteOpnd lsrc, rsrc = rewriteOpnd rsrc}
| I.TESTB{lsrc, rsrc} =>
I.TESTB{lsrc = rewriteOpnd lsrc, rsrc = rewriteOpnd rsrc}
| I.BITOP{bitOp, lsrc, rsrc} => I.BITOP{
bitOp = bitOp,
lsrc = rewriteOpnd lsrc,
rsrc = rewriteOpnd rsrc
}
| I.BINARY{binOp, src, dst} => I.BINARY{
binOp = binOp,
src = rewriteOpnd src,
dst = rewriteOpnd dst
}
| I.MULTDIV{multDivOp, src} => I.MULTDIV{
multDivOp = multDivOp, src = rewriteOpnd src
}
| I.MUL3{dst, src2, src1} => I.MUL3{
dst = dst, src2 = src2, src1 = rewriteOpnd src1
}
| I.UNARY{unOp, opnd} =>
I.UNARY{unOp = unOp, opnd = rewriteOpnd opnd}
| I.SET{cond, opnd} => I.SET{cond = cond, opnd = rewriteOpnd opnd}
| I.CMOV{cond, src, dst} => I.CMOV{
cond = cond, src = rewriteOpnd src, dst = dst
}
| I.PUSHL _ => error "unexpected pushl"
| I.PUSHW _ => error "unexpected pushw"
| I.PUSHB _ => error "unexpected pushb"
| I.POP _ => error "unexpected popl"
| I.COPY _ => error "unexpected copy"
| I.FCOPY _ => error "unexpected fcopy"
| I.FBINARY{binOp, src, dst} => I.FBINARY{
binOp = binOp, src = rewriteOpnd src, dst = rewriteOpnd dst
}
| I.FIBINARY{binOp, src} => I.FIBINARY{
binOp = binOp, src = rewriteOpnd src
}
| I.FUCOM opnd => I.FUCOM(rewriteOpnd opnd)
| I.FUCOMP opnd => I.FUCOMP(rewriteOpnd opnd)
| I.FSTPL opnd => I.FSTPL(rewriteOpnd opnd)
| I.FSTPS opnd => I.FSTPS(rewriteOpnd opnd)
| I.FSTPT opnd => I.FSTPT(rewriteOpnd opnd)
| I.FSTL opnd => I.FSTL(rewriteOpnd opnd)
| I.FSTS opnd => I.FSTS(rewriteOpnd opnd)
| I.FLDL opnd => I.FLDL(rewriteOpnd opnd)
| I.FLDS opnd => I.FLDS(rewriteOpnd opnd)
| I.FLDT opnd => I.FLDT(rewriteOpnd opnd)
| I.FILD opnd => I.FILD(rewriteOpnd opnd)
| I.FILDL opnd => I.FILDL(rewriteOpnd opnd)
| I.FILDLL opnd => I.FILDLL(rewriteOpnd opnd)
| I.FENV{fenvOp, opnd} =>
I.FENV{fenvOp = fenvOp, opnd = rewriteOpnd opnd}
| I.ANNOTATION{i, a} => I.ANNOTATION{i = rewriteInsn i, a = a}
| _ => insn
(* end case *))
(* rewrite the instructions of a block *)
fun rewriteBlock (F.BBLOCK{insns, ...}) =
insns := List.map rewriteInsn (!insns)
| rewriteBlock _ = ()
(* rewrite the exit protocol of an exit block *)
fun rewriteExit (F.BBLOCK{blknum, insns, ...}, _) = (
case !insns
of (ret as I.RET _)::I.LEAVE::rest =>
insns := ret :: rest
| (I.JMP _ :: _) => () (* non-local control flow *)
| _ => err(blknum,"unable to rewrite exit protocol")
(* end case *))
(* rewrite the entry protocol of an entry block *)
fun rewriteEntry (F.BBLOCK{blknum, insns, ...}, _) = let
fun rewrite [
I.BINARY{binOp=I.SUBL, src=I.ImmedLabel _, dst=I.Direct a},
I.MOVE{mvOp=I.MOVL, src=I.Direct b, dst=I.Direct c},
I.PUSHL(I.Direct d)
] = if ((isSP a) andalso (isSP b)
andalso (isFP c) andalso (isFP d))
then []
else err(blknum, "unable to rewrite entry protocol")
| rewrite (insn::rest) = insn :: rewrite rest
| rewrite [] = err(blknum, "unable to rewrite entry protocol")
in
insns := rewrite(!insns)
end
in
(* first, we rewrite the exit and entry blocks *)
case #exit cluster
of F.EXIT{pred, ...} => List.app rewriteExit (!pred)
(* end case *);
case #entry cluster
of F.ENTRY{succ, ...} => List.app rewriteEntry (!succ)
(* end case *);
(* then rewrite the instructions to use the %esp instead of %ebp *)
List.app rewriteBlock (#blocks cluster)
end
fun run cluster =
(if isLeaf cluster then optimize cluster else (); cluster)
end
|
