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// Inferno utils/5c/peep.c
// http://code.google.com/p/inferno-os/source/browse/utils/5c/peep.c
//
// Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved.
// Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
// Portions Copyright © 1997-1999 Vita Nuova Limited
// Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
// Portions Copyright © 2004,2006 Bruce Ellis
// Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
// Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
// Portions Copyright © 2009 The Go Authors. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package main
import (
"cmd/internal/gc"
"cmd/internal/obj"
"cmd/internal/obj/arm"
"fmt"
)
var gactive uint32
// UNUSED
func peep(firstp *obj.Prog) {
g := (*gc.Graph)(gc.Flowstart(firstp, nil))
if g == nil {
return
}
gactive = 0
var r *gc.Flow
var p *obj.Prog
var t int
loop1:
if gc.Debug['P'] != 0 && gc.Debug['v'] != 0 {
gc.Dumpit("loop1", g.Start, 0)
}
t = 0
for r = g.Start; r != nil; r = r.Link {
p = r.Prog
switch p.As {
/*
* elide shift into TYPE_SHIFT operand of subsequent instruction
*/
// if(shiftprop(r)) {
// excise(r);
// t++;
// break;
// }
case arm.ASLL,
arm.ASRL,
arm.ASRA:
break
case arm.AMOVB,
arm.AMOVH,
arm.AMOVW,
arm.AMOVF,
arm.AMOVD:
if regtyp(&p.From) {
if p.From.Type == p.To.Type && isfloatreg(&p.From) == isfloatreg(&p.To) {
if p.Scond == arm.C_SCOND_NONE {
if copyprop(g, r) {
excise(r)
t++
break
}
if subprop(r) && copyprop(g, r) {
excise(r)
t++
break
}
}
}
}
case arm.AMOVHS,
arm.AMOVHU,
arm.AMOVBS,
arm.AMOVBU:
if p.From.Type == obj.TYPE_REG {
if shortprop(r) {
t++
}
}
}
}
/*
if(p->scond == C_SCOND_NONE)
if(regtyp(&p->to))
if(isdconst(&p->from)) {
constprop(&p->from, &p->to, r->s1);
}
break;
*/
if t != 0 {
goto loop1
}
for r := (*gc.Flow)(g.Start); r != nil; r = r.Link {
p = r.Prog
switch p.As {
/*
* EOR -1,x,y => MVN x,y
*/
case arm.AEOR:
if isdconst(&p.From) && p.From.Offset == -1 {
p.As = arm.AMVN
p.From.Type = obj.TYPE_REG
if p.Reg != 0 {
p.From.Reg = p.Reg
} else {
p.From.Reg = p.To.Reg
}
p.Reg = 0
}
}
}
for r := (*gc.Flow)(g.Start); r != nil; r = r.Link {
p = r.Prog
switch p.As {
case arm.AMOVW,
arm.AMOVB,
arm.AMOVBS,
arm.AMOVBU:
if p.From.Type == obj.TYPE_MEM && p.From.Offset == 0 {
xtramodes(g, r, &p.From)
} else if p.To.Type == obj.TYPE_MEM && p.To.Offset == 0 {
xtramodes(g, r, &p.To)
} else {
continue
}
}
}
// case ACMP:
// /*
// * elide CMP $0,x if calculation of x can set condition codes
// */
// if(isdconst(&p->from) || p->from.offset != 0)
// continue;
// r2 = r->s1;
// if(r2 == nil)
// continue;
// t = r2->prog->as;
// switch(t) {
// default:
// continue;
// case ABEQ:
// case ABNE:
// case ABMI:
// case ABPL:
// break;
// case ABGE:
// t = ABPL;
// break;
// case ABLT:
// t = ABMI;
// break;
// case ABHI:
// t = ABNE;
// break;
// case ABLS:
// t = ABEQ;
// break;
// }
// r1 = r;
// do
// r1 = uniqp(r1);
// while (r1 != nil && r1->prog->as == ANOP);
// if(r1 == nil)
// continue;
// p1 = r1->prog;
// if(p1->to.type != TYPE_REG)
// continue;
// if(p1->to.reg != p->reg)
// if(!(p1->as == AMOVW && p1->from.type == TYPE_REG && p1->from.reg == p->reg))
// continue;
//
// switch(p1->as) {
// default:
// continue;
// case AMOVW:
// if(p1->from.type != TYPE_REG)
// continue;
// case AAND:
// case AEOR:
// case AORR:
// case ABIC:
// case AMVN:
// case ASUB:
// case ARSB:
// case AADD:
// case AADC:
// case ASBC:
// case ARSC:
// break;
// }
// p1->scond |= C_SBIT;
// r2->prog->as = t;
// excise(r);
// continue;
// predicate(g);
gc.Flowend(g)
}
func regtyp(a *obj.Addr) bool {
return a.Type == obj.TYPE_REG && (arm.REG_R0 <= a.Reg && a.Reg <= arm.REG_R15 || arm.REG_F0 <= a.Reg && a.Reg <= arm.REG_F15)
}
/*
* the idea is to substitute
* one register for another
* from one MOV to another
* MOV a, R0
* ADD b, R0 / no use of R1
* MOV R0, R1
* would be converted to
* MOV a, R1
* ADD b, R1
* MOV R1, R0
* hopefully, then the former or latter MOV
* will be eliminated by copy propagation.
*/
func subprop(r0 *gc.Flow) bool {
p := (*obj.Prog)(r0.Prog)
v1 := (*obj.Addr)(&p.From)
if !regtyp(v1) {
return false
}
v2 := (*obj.Addr)(&p.To)
if !regtyp(v2) {
return false
}
for r := gc.Uniqp(r0); r != nil; r = gc.Uniqp(r) {
if gc.Uniqs(r) == nil {
break
}
p = r.Prog
if p.As == obj.AVARDEF || p.As == obj.AVARKILL {
continue
}
if p.Info.Flags&gc.Call != 0 {
return false
}
// TODO(rsc): Whatever invalidated the info should have done this call.
proginfo(p)
if (p.Info.Flags&gc.CanRegRead != 0) && p.To.Type == obj.TYPE_REG {
p.Info.Flags |= gc.RegRead
p.Info.Flags &^= (gc.CanRegRead | gc.RightRead)
p.Reg = p.To.Reg
}
switch p.As {
case arm.AMULLU,
arm.AMULA,
arm.AMVN:
return false
}
if p.Info.Flags&(gc.RightRead|gc.RightWrite) == gc.RightWrite {
if p.To.Type == v1.Type {
if p.To.Reg == v1.Reg {
if p.Scond == arm.C_SCOND_NONE {
copysub(&p.To, v1, v2, 1)
if gc.Debug['P'] != 0 {
fmt.Printf("gotit: %v->%v\n%v", gc.Ctxt.Dconv(v1), gc.Ctxt.Dconv(v2), r.Prog)
if p.From.Type == v2.Type {
fmt.Printf(" excise")
}
fmt.Printf("\n")
}
for r = gc.Uniqs(r); r != r0; r = gc.Uniqs(r) {
p = r.Prog
copysub(&p.From, v1, v2, 1)
copysub1(p, v1, v2, 1)
copysub(&p.To, v1, v2, 1)
if gc.Debug['P'] != 0 {
fmt.Printf("%v\n", r.Prog)
}
}
t := int(int(v1.Reg))
v1.Reg = v2.Reg
v2.Reg = int16(t)
if gc.Debug['P'] != 0 {
fmt.Printf("%v last\n", r.Prog)
}
return true
}
}
}
}
if copyau(&p.From, v2) || copyau1(p, v2) || copyau(&p.To, v2) {
break
}
if copysub(&p.From, v1, v2, 0) != 0 || copysub1(p, v1, v2, 0) != 0 || copysub(&p.To, v1, v2, 0) != 0 {
break
}
}
return false
}
/*
* The idea is to remove redundant copies.
* v1->v2 F=0
* (use v2 s/v2/v1/)*
* set v1 F=1
* use v2 return fail
* -----------------
* v1->v2 F=0
* (use v2 s/v2/v1/)*
* set v1 F=1
* set v2 return success
*/
func copyprop(g *gc.Graph, r0 *gc.Flow) bool {
p := (*obj.Prog)(r0.Prog)
v1 := (*obj.Addr)(&p.From)
v2 := (*obj.Addr)(&p.To)
if copyas(v1, v2) {
return true
}
gactive++
return copy1(v1, v2, r0.S1, 0)
}
func copy1(v1 *obj.Addr, v2 *obj.Addr, r *gc.Flow, f int) bool {
if uint32(r.Active) == gactive {
if gc.Debug['P'] != 0 {
fmt.Printf("act set; return 1\n")
}
return true
}
r.Active = int32(gactive)
if gc.Debug['P'] != 0 {
fmt.Printf("copy %v->%v f=%d\n", gc.Ctxt.Dconv(v1), gc.Ctxt.Dconv(v2), f)
}
var t int
var p *obj.Prog
for ; r != nil; r = r.S1 {
p = r.Prog
if gc.Debug['P'] != 0 {
fmt.Printf("%v", p)
}
if f == 0 && gc.Uniqp(r) == nil {
f = 1
if gc.Debug['P'] != 0 {
fmt.Printf("; merge; f=%d", f)
}
}
t = copyu(p, v2, nil)
switch t {
case 2: /* rar, can't split */
if gc.Debug['P'] != 0 {
fmt.Printf("; %vrar; return 0\n", gc.Ctxt.Dconv(v2))
}
return false
case 3: /* set */
if gc.Debug['P'] != 0 {
fmt.Printf("; %vset; return 1\n", gc.Ctxt.Dconv(v2))
}
return true
case 1, /* used, substitute */
4: /* use and set */
if f != 0 {
if gc.Debug['P'] == 0 {
return false
}
if t == 4 {
fmt.Printf("; %vused+set and f=%d; return 0\n", gc.Ctxt.Dconv(v2), f)
} else {
fmt.Printf("; %vused and f=%d; return 0\n", gc.Ctxt.Dconv(v2), f)
}
return false
}
if copyu(p, v2, v1) != 0 {
if gc.Debug['P'] != 0 {
fmt.Printf("; sub fail; return 0\n")
}
return false
}
if gc.Debug['P'] != 0 {
fmt.Printf("; sub%v/%v", gc.Ctxt.Dconv(v2), gc.Ctxt.Dconv(v1))
}
if t == 4 {
if gc.Debug['P'] != 0 {
fmt.Printf("; %vused+set; return 1\n", gc.Ctxt.Dconv(v2))
}
return true
}
}
if f == 0 {
t = copyu(p, v1, nil)
if f == 0 && (t == 2 || t == 3 || t == 4) {
f = 1
if gc.Debug['P'] != 0 {
fmt.Printf("; %vset and !f; f=%d", gc.Ctxt.Dconv(v1), f)
}
}
}
if gc.Debug['P'] != 0 {
fmt.Printf("\n")
}
if r.S2 != nil {
if !copy1(v1, v2, r.S2, f) {
return false
}
}
}
return true
}
// UNUSED
/*
* The idea is to remove redundant constants.
* $c1->v1
* ($c1->v2 s/$c1/v1)*
* set v1 return
* The v1->v2 should be eliminated by copy propagation.
*/
func constprop(c1 *obj.Addr, v1 *obj.Addr, r *gc.Flow) {
if gc.Debug['P'] != 0 {
fmt.Printf("constprop %v->%v\n", gc.Ctxt.Dconv(c1), gc.Ctxt.Dconv(v1))
}
var p *obj.Prog
for ; r != nil; r = r.S1 {
p = r.Prog
if gc.Debug['P'] != 0 {
fmt.Printf("%v", p)
}
if gc.Uniqp(r) == nil {
if gc.Debug['P'] != 0 {
fmt.Printf("; merge; return\n")
}
return
}
if p.As == arm.AMOVW && copyas(&p.From, c1) {
if gc.Debug['P'] != 0 {
fmt.Printf("; sub%v/%v", gc.Ctxt.Dconv(&p.From), gc.Ctxt.Dconv(v1))
}
p.From = *v1
} else if copyu(p, v1, nil) > 1 {
if gc.Debug['P'] != 0 {
fmt.Printf("; %vset; return\n", gc.Ctxt.Dconv(v1))
}
return
}
if gc.Debug['P'] != 0 {
fmt.Printf("\n")
}
if r.S2 != nil {
constprop(c1, v1, r.S2)
}
}
}
/*
* shortprop eliminates redundant zero/sign extensions.
*
* MOVBS x, R
* <no use R>
* MOVBS R, R'
*
* changed to
*
* MOVBS x, R
* ...
* MOVB R, R' (compiled to mov)
*
* MOVBS above can be a MOVBS, MOVBU, MOVHS or MOVHU.
*/
func shortprop(r *gc.Flow) bool {
p := (*obj.Prog)(r.Prog)
r1 := (*gc.Flow)(findpre(r, &p.From))
if r1 == nil {
return false
}
p1 := (*obj.Prog)(r1.Prog)
if p1.As == p.As {
// Two consecutive extensions.
goto gotit
}
if p1.As == arm.AMOVW && isdconst(&p1.From) && p1.From.Offset >= 0 && p1.From.Offset < 128 {
// Loaded an immediate.
goto gotit
}
return false
gotit:
if gc.Debug['P'] != 0 {
fmt.Printf("shortprop\n%v\n%v", p1, p)
}
switch p.As {
case arm.AMOVBS,
arm.AMOVBU:
p.As = arm.AMOVB
case arm.AMOVHS,
arm.AMOVHU:
p.As = arm.AMOVH
}
if gc.Debug['P'] != 0 {
fmt.Printf(" => %v\n", obj.Aconv(int(p.As)))
}
return true
}
// UNUSED
/*
* ASLL x,y,w
* .. (not use w, not set x y w)
* AXXX w,a,b (a != w)
* .. (not use w)
* (set w)
* ----------- changed to
* ..
* AXXX (x<<y),a,b
* ..
*/
func shiftprop(r *gc.Flow) bool {
p := (*obj.Prog)(r.Prog)
if p.To.Type != obj.TYPE_REG {
if gc.Debug['P'] != 0 {
fmt.Printf("\tBOTCH: result not reg; FAILURE\n")
}
return false
}
n := int(int(p.To.Reg))
a := obj.Addr(obj.Addr{})
if p.Reg != 0 && p.Reg != p.To.Reg {
a.Type = obj.TYPE_REG
a.Reg = p.Reg
}
if gc.Debug['P'] != 0 {
fmt.Printf("shiftprop\n%v", p)
}
r1 := (*gc.Flow)(r)
var p1 *obj.Prog
for {
/* find first use of shift result; abort if shift operands or result are changed */
r1 = gc.Uniqs(r1)
if r1 == nil {
if gc.Debug['P'] != 0 {
fmt.Printf("\tbranch; FAILURE\n")
}
return false
}
if gc.Uniqp(r1) == nil {
if gc.Debug['P'] != 0 {
fmt.Printf("\tmerge; FAILURE\n")
}
return false
}
p1 = r1.Prog
if gc.Debug['P'] != 0 {
fmt.Printf("\n%v", p1)
}
switch copyu(p1, &p.To, nil) {
case 0: /* not used or set */
if (p.From.Type == obj.TYPE_REG && copyu(p1, &p.From, nil) > 1) || (a.Type == obj.TYPE_REG && copyu(p1, &a, nil) > 1) {
if gc.Debug['P'] != 0 {
fmt.Printf("\targs modified; FAILURE\n")
}
return false
}
continue
case 3: /* set, not used */
{
if gc.Debug['P'] != 0 {
fmt.Printf("\tBOTCH: noref; FAILURE\n")
}
return false
}
}
break
}
/* check whether substitution can be done */
switch p1.As {
default:
if gc.Debug['P'] != 0 {
fmt.Printf("\tnon-dpi; FAILURE\n")
}
return false
case arm.AAND,
arm.AEOR,
arm.AADD,
arm.AADC,
arm.AORR,
arm.ASUB,
arm.ASBC,
arm.ARSB,
arm.ARSC:
if int(p1.Reg) == n || (p1.Reg == 0 && p1.To.Type == obj.TYPE_REG && int(p1.To.Reg) == n) {
if p1.From.Type != obj.TYPE_REG {
if gc.Debug['P'] != 0 {
fmt.Printf("\tcan't swap; FAILURE\n")
}
return false
}
p1.Reg = p1.From.Reg
p1.From.Reg = int16(n)
switch p1.As {
case arm.ASUB:
p1.As = arm.ARSB
case arm.ARSB:
p1.As = arm.ASUB
case arm.ASBC:
p1.As = arm.ARSC
case arm.ARSC:
p1.As = arm.ASBC
}
if gc.Debug['P'] != 0 {
fmt.Printf("\t=>%v", p1)
}
}
fallthrough
case arm.ABIC,
arm.ATST,
arm.ACMP,
arm.ACMN:
if int(p1.Reg) == n {
if gc.Debug['P'] != 0 {
fmt.Printf("\tcan't swap; FAILURE\n")
}
return false
}
if p1.Reg == 0 && int(p1.To.Reg) == n {
if gc.Debug['P'] != 0 {
fmt.Printf("\tshift result used twice; FAILURE\n")
}
return false
}
// case AMVN:
if p1.From.Type == obj.TYPE_SHIFT {
if gc.Debug['P'] != 0 {
fmt.Printf("\tshift result used in shift; FAILURE\n")
}
return false
}
if p1.From.Type != obj.TYPE_REG || int(p1.From.Reg) != n {
if gc.Debug['P'] != 0 {
fmt.Printf("\tBOTCH: where is it used?; FAILURE\n")
}
return false
}
}
/* check whether shift result is used subsequently */
p2 := (*obj.Prog)(p1)
if int(p1.To.Reg) != n {
var p1 *obj.Prog
for {
r1 = gc.Uniqs(r1)
if r1 == nil {
if gc.Debug['P'] != 0 {
fmt.Printf("\tinconclusive; FAILURE\n")
}
return false
}
p1 = r1.Prog
if gc.Debug['P'] != 0 {
fmt.Printf("\n%v", p1)
}
switch copyu(p1, &p.To, nil) {
case 0: /* not used or set */
continue
case 3: /* set, not used */
break
default: /* used */
if gc.Debug['P'] != 0 {
fmt.Printf("\treused; FAILURE\n")
}
return false
}
break
}
}
/* make the substitution */
p2.From.Reg = 0
o := int(int(p.Reg))
if o == 0 {
o = int(p.To.Reg)
}
o &= 15
switch p.From.Type {
case obj.TYPE_CONST:
o |= int((p.From.Offset & 0x1f) << 7)
case obj.TYPE_REG:
o |= 1<<4 | (int(p.From.Reg)&15)<<8
}
switch p.As {
case arm.ASLL:
o |= 0 << 5
case arm.ASRL:
o |= 1 << 5
case arm.ASRA:
o |= 2 << 5
}
p2.From = obj.Addr{}
p2.From.Type = obj.TYPE_SHIFT
p2.From.Offset = int64(o)
if gc.Debug['P'] != 0 {
fmt.Printf("\t=>%v\tSUCCEED\n", p2)
}
return true
}
/*
* findpre returns the last instruction mentioning v
* before r. It must be a set, and there must be
* a unique path from that instruction to r.
*/
func findpre(r *gc.Flow, v *obj.Addr) *gc.Flow {
var r1 *gc.Flow
for r1 = gc.Uniqp(r); r1 != nil; r, r1 = r1, gc.Uniqp(r1) {
if gc.Uniqs(r1) != r {
return nil
}
switch copyu(r1.Prog, v, nil) {
case 1, /* used */
2: /* read-alter-rewrite */
return nil
case 3, /* set */
4: /* set and used */
return r1
}
}
return nil
}
/*
* findinc finds ADD instructions with a constant
* argument which falls within the immed_12 range.
*/
func findinc(r *gc.Flow, r2 *gc.Flow, v *obj.Addr) *gc.Flow {
var r1 *gc.Flow
var p *obj.Prog
for r1 = gc.Uniqs(r); r1 != nil && r1 != r2; r, r1 = r1, gc.Uniqs(r1) {
if gc.Uniqp(r1) != r {
return nil
}
switch copyu(r1.Prog, v, nil) {
case 0: /* not touched */
continue
case 4: /* set and used */
p = r1.Prog
if p.As == arm.AADD {
if isdconst(&p.From) {
if p.From.Offset > -4096 && p.From.Offset < 4096 {
return r1
}
}
}
fallthrough
default:
return nil
}
}
return nil
}
func nochange(r *gc.Flow, r2 *gc.Flow, p *obj.Prog) bool {
if r == r2 {
return true
}
n := int(0)
var a [3]obj.Addr
if p.Reg != 0 && p.Reg != p.To.Reg {
a[n].Type = obj.TYPE_REG
a[n].Reg = p.Reg
n++
}
switch p.From.Type {
case obj.TYPE_SHIFT:
a[n].Type = obj.TYPE_REG
a[n].Reg = int16(arm.REG_R0 + (p.From.Offset & 0xf))
n++
fallthrough
case obj.TYPE_REG:
a[n].Type = obj.TYPE_REG
a[n].Reg = p.From.Reg
n++
}
if n == 0 {
return true
}
var i int
for ; r != nil && r != r2; r = gc.Uniqs(r) {
p = r.Prog
for i = 0; i < n; i++ {
if copyu(p, &a[i], nil) > 1 {
return false
}
}
}
return true
}
func findu1(r *gc.Flow, v *obj.Addr) bool {
for ; r != nil; r = r.S1 {
if r.Active != 0 {
return false
}
r.Active = 1
switch copyu(r.Prog, v, nil) {
case 1, /* used */
2, /* read-alter-rewrite */
4: /* set and used */
return true
case 3: /* set */
return false
}
if r.S2 != nil {
if findu1(r.S2, v) {
return true
}
}
}
return false
}
func finduse(g *gc.Graph, r *gc.Flow, v *obj.Addr) bool {
for r1 := (*gc.Flow)(g.Start); r1 != nil; r1 = r1.Link {
r1.Active = 0
}
return findu1(r, v)
}
/*
* xtramodes enables the ARM post increment and
* shift offset addressing modes to transform
* MOVW 0(R3),R1
* ADD $4,R3,R3
* into
* MOVW.P 4(R3),R1
* and
* ADD R0,R1
* MOVBU 0(R1),R0
* into
* MOVBU R0<<0(R1),R0
*/
func xtramodes(g *gc.Graph, r *gc.Flow, a *obj.Addr) bool {
p := (*obj.Prog)(r.Prog)
v := obj.Addr(*a)
v.Type = obj.TYPE_REG
r1 := (*gc.Flow)(findpre(r, &v))
if r1 != nil {
p1 := r1.Prog
if p1.To.Type == obj.TYPE_REG && p1.To.Reg == v.Reg {
switch p1.As {
case arm.AADD:
if p1.Scond&arm.C_SBIT != 0 {
// avoid altering ADD.S/ADC sequences.
break
}
if p1.From.Type == obj.TYPE_REG || (p1.From.Type == obj.TYPE_SHIFT && p1.From.Offset&(1<<4) == 0 && ((p.As != arm.AMOVB && p.As != arm.AMOVBS) || (a == &p.From && p1.From.Offset&^0xf == 0))) || ((p1.From.Type == obj.TYPE_ADDR || p1.From.Type == obj.TYPE_CONST) && p1.From.Offset > -4096 && p1.From.Offset < 4096) {
if nochange(gc.Uniqs(r1), r, p1) {
if a != &p.From || v.Reg != p.To.Reg {
if finduse(g, r.S1, &v) {
if p1.Reg == 0 || p1.Reg == v.Reg {
/* pre-indexing */
p.Scond |= arm.C_WBIT
} else {
return false
}
}
}
switch p1.From.Type {
/* register offset */
case obj.TYPE_REG:
if gc.Nacl {
return false
}
*a = obj.Addr{}
a.Type = obj.TYPE_SHIFT
a.Offset = int64(p1.From.Reg) & 15
/* scaled register offset */
case obj.TYPE_SHIFT:
if gc.Nacl {
return false
}
*a = obj.Addr{}
a.Type = obj.TYPE_SHIFT
fallthrough
/* immediate offset */
case obj.TYPE_CONST,
obj.TYPE_ADDR:
a.Offset = p1.From.Offset
}
if p1.Reg != 0 {
a.Reg = p1.Reg
}
excise(r1)
return true
}
}
case arm.AMOVW:
if p1.From.Type == obj.TYPE_REG {
r2 := (*gc.Flow)(findinc(r1, r, &p1.From))
if r2 != nil {
var r3 *gc.Flow
for r3 = gc.Uniqs(r2); r3.Prog.As == obj.ANOP; r3 = gc.Uniqs(r3) {
}
if r3 == r {
/* post-indexing */
p1 := r2.Prog
a.Reg = p1.To.Reg
a.Offset = p1.From.Offset
p.Scond |= arm.C_PBIT
if !finduse(g, r, &r1.Prog.To) {
excise(r1)
}
excise(r2)
return true
}
}
}
}
}
}
if a != &p.From || a.Reg != p.To.Reg {
r1 := (*gc.Flow)(findinc(r, nil, &v))
if r1 != nil {
/* post-indexing */
p1 := r1.Prog
a.Offset = p1.From.Offset
p.Scond |= arm.C_PBIT
excise(r1)
return true
}
}
return false
}
/*
* return
* 1 if v only used (and substitute),
* 2 if read-alter-rewrite
* 3 if set
* 4 if set and used
* 0 otherwise (not touched)
*/
func copyu(p *obj.Prog, v *obj.Addr, s *obj.Addr) int {
switch p.As {
default:
fmt.Printf("copyu: can't find %v\n", obj.Aconv(int(p.As)))
return 2
case arm.AMOVM:
if v.Type != obj.TYPE_REG {
return 0
}
if p.From.Type == obj.TYPE_CONST { /* read reglist, read/rar */
if s != nil {
if p.From.Offset&(1<<uint(v.Reg)) != 0 {
return 1
}
if copysub(&p.To, v, s, 1) != 0 {
return 1
}
return 0
}
if copyau(&p.To, v) {
if p.Scond&arm.C_WBIT != 0 {
return 2
}
return 1
}
if p.From.Offset&(1<<uint(v.Reg)) != 0 {
return 1 /* read/rar, write reglist */
}
} else {
if s != nil {
if p.To.Offset&(1<<uint(v.Reg)) != 0 {
return 1
}
if copysub(&p.From, v, s, 1) != 0 {
return 1
}
return 0
}
if copyau(&p.From, v) {
if p.Scond&arm.C_WBIT != 0 {
return 2
}
if p.To.Offset&(1<<uint(v.Reg)) != 0 {
return 4
}
return 1
}
if p.To.Offset&(1<<uint(v.Reg)) != 0 {
return 3
}
}
return 0
case obj.ANOP, /* read,, write */
arm.AMOVW,
arm.AMOVF,
arm.AMOVD,
arm.AMOVH,
arm.AMOVHS,
arm.AMOVHU,
arm.AMOVB,
arm.AMOVBS,
arm.AMOVBU,
arm.AMOVFW,
arm.AMOVWF,
arm.AMOVDW,
arm.AMOVWD,
arm.AMOVFD,
arm.AMOVDF:
if p.Scond&(arm.C_WBIT|arm.C_PBIT) != 0 {
if v.Type == obj.TYPE_REG {
if p.From.Type == obj.TYPE_MEM || p.From.Type == obj.TYPE_SHIFT {
if p.From.Reg == v.Reg {
return 2
}
} else {
if p.To.Reg == v.Reg {
return 2
}
}
}
}
if s != nil {
if copysub(&p.From, v, s, 1) != 0 {
return 1
}
if !copyas(&p.To, v) {
if copysub(&p.To, v, s, 1) != 0 {
return 1
}
}
return 0
}
if copyas(&p.To, v) {
if p.Scond != arm.C_SCOND_NONE {
return 2
}
if copyau(&p.From, v) {
return 4
}
return 3
}
if copyau(&p.From, v) {
return 1
}
if copyau(&p.To, v) {
return 1
}
return 0
case arm.AMULLU, /* read, read, write, write */
arm.AMULL,
arm.AMULA,
arm.AMVN:
return 2
case arm.AADD, /* read, read, write */
arm.AADC,
arm.ASUB,
arm.ASBC,
arm.ARSB,
arm.ASLL,
arm.ASRL,
arm.ASRA,
arm.AORR,
arm.AAND,
arm.AEOR,
arm.AMUL,
arm.AMULU,
arm.ADIV,
arm.ADIVU,
arm.AMOD,
arm.AMODU,
arm.AADDF,
arm.AADDD,
arm.ASUBF,
arm.ASUBD,
arm.AMULF,
arm.AMULD,
arm.ADIVF,
arm.ADIVD,
obj.ACHECKNIL,
/* read */
arm.ACMPF, /* read, read, */
arm.ACMPD,
arm.ACMP,
arm.ACMN,
arm.ACASE,
arm.ATST:
/* read,, */
if s != nil {
if copysub(&p.From, v, s, 1) != 0 {
return 1
}
if copysub1(p, v, s, 1) != 0 {
return 1
}
if !copyas(&p.To, v) {
if copysub(&p.To, v, s, 1) != 0 {
return 1
}
}
return 0
}
if copyas(&p.To, v) {
if p.Scond != arm.C_SCOND_NONE {
return 2
}
if p.Reg == 0 {
p.Reg = p.To.Reg
}
if copyau(&p.From, v) {
return 4
}
if copyau1(p, v) {
return 4
}
return 3
}
if copyau(&p.From, v) {
return 1
}
if copyau1(p, v) {
return 1
}
if copyau(&p.To, v) {
return 1
}
return 0
case arm.ABEQ, /* read, read */
arm.ABNE,
arm.ABCS,
arm.ABHS,
arm.ABCC,
arm.ABLO,
arm.ABMI,
arm.ABPL,
arm.ABVS,
arm.ABVC,
arm.ABHI,
arm.ABLS,
arm.ABGE,
arm.ABLT,
arm.ABGT,
arm.ABLE:
if s != nil {
if copysub(&p.From, v, s, 1) != 0 {
return 1
}
return copysub1(p, v, s, 1)
}
if copyau(&p.From, v) {
return 1
}
if copyau1(p, v) {
return 1
}
return 0
case arm.AB: /* funny */
if s != nil {
if copysub(&p.To, v, s, 1) != 0 {
return 1
}
return 0
}
if copyau(&p.To, v) {
return 1
}
return 0
case obj.ARET: /* funny */
if s != nil {
return 1
}
return 3
case arm.ABL: /* funny */
if v.Type == obj.TYPE_REG {
// TODO(rsc): REG_R0 and REG_F0 used to be
// (when register numbers started at 0) exregoffset and exfregoffset,
// which are unset entirely.
// It's strange that this handles R0 and F0 differently from the other
// registers. Possible failure to optimize?
if arm.REG_R0 < v.Reg && v.Reg <= arm.REGEXT {
return 2
}
if v.Reg == arm.REGARG {
return 2
}
if arm.REG_F0 < v.Reg && v.Reg <= arm.FREGEXT {
return 2
}
}
if p.From.Type == obj.TYPE_REG && v.Type == obj.TYPE_REG && p.From.Reg == v.Reg {
return 2
}
if s != nil {
if copysub(&p.To, v, s, 1) != 0 {
return 1
}
return 0
}
if copyau(&p.To, v) {
return 4
}
return 3
// R0 is zero, used by DUFFZERO, cannot be substituted.
// R1 is ptr to memory, used and set, cannot be substituted.
case obj.ADUFFZERO:
if v.Type == obj.TYPE_REG {
if v.Reg == arm.REG_R0 {
return 1
}
if v.Reg == arm.REG_R0+1 {
return 2
}
}
return 0
// R0 is scratch, set by DUFFCOPY, cannot be substituted.
// R1, R2 areptr to src, dst, used and set, cannot be substituted.
case obj.ADUFFCOPY:
if v.Type == obj.TYPE_REG {
if v.Reg == arm.REG_R0 {
return 3
}
if v.Reg == arm.REG_R0+1 || v.Reg == arm.REG_R0+2 {
return 2
}
}
return 0
case obj.ATEXT: /* funny */
if v.Type == obj.TYPE_REG {
if v.Reg == arm.REGARG {
return 3
}
}
return 0
case obj.APCDATA,
obj.AFUNCDATA,
obj.AVARDEF,
obj.AVARKILL:
return 0
}
}
/*
* direct reference,
* could be set/use depending on
* semantics
*/
func copyas(a *obj.Addr, v *obj.Addr) bool {
if regtyp(v) {
if a.Type == v.Type {
if a.Reg == v.Reg {
return true
}
}
} else if v.Type == obj.TYPE_CONST { /* for constprop */
if a.Type == v.Type {
if a.Name == v.Name {
if a.Sym == v.Sym {
if a.Reg == v.Reg {
if a.Offset == v.Offset {
return true
}
}
}
}
}
}
return false
}
func sameaddr(a *obj.Addr, v *obj.Addr) bool {
if a.Type != v.Type {
return false
}
if regtyp(v) && a.Reg == v.Reg {
return true
}
// TODO(rsc): Change v->type to v->name and enable.
//if(v->type == NAME_AUTO || v->type == NAME_PARAM) {
// if(v->offset == a->offset)
// return 1;
//}
return false
}
/*
* either direct or indirect
*/
func copyau(a *obj.Addr, v *obj.Addr) bool {
if copyas(a, v) {
return true
}
if v.Type == obj.TYPE_REG {
if a.Type == obj.TYPE_ADDR && a.Reg != 0 {
if a.Reg == v.Reg {
return true
}
} else if a.Type == obj.TYPE_MEM {
if a.Reg == v.Reg {
return true
}
} else if a.Type == obj.TYPE_REGREG || a.Type == obj.TYPE_REGREG2 {
if a.Reg == v.Reg {
return true
}
if a.Offset == int64(v.Reg) {
return true
}
} else if a.Type == obj.TYPE_SHIFT {
if a.Offset&0xf == int64(v.Reg-arm.REG_R0) {
return true
}
if (a.Offset&(1<<4) != 0) && (a.Offset>>8)&0xf == int64(v.Reg-arm.REG_R0) {
return true
}
}
}
return false
}
/*
* compare v to the center
* register in p (p->reg)
*/
func copyau1(p *obj.Prog, v *obj.Addr) bool {
if v.Type == obj.TYPE_REG && v.Reg == 0 {
return false
}
return p.Reg == v.Reg
}
/*
* substitute s for v in a
* return failure to substitute
*/
func copysub(a *obj.Addr, v *obj.Addr, s *obj.Addr, f int) int {
if f != 0 {
if copyau(a, v) {
if a.Type == obj.TYPE_SHIFT {
if a.Offset&0xf == int64(v.Reg-arm.REG_R0) {
a.Offset = a.Offset&^0xf | int64(s.Reg)&0xf
}
if (a.Offset&(1<<4) != 0) && (a.Offset>>8)&0xf == int64(v.Reg-arm.REG_R0) {
a.Offset = a.Offset&^(0xf<<8) | (int64(s.Reg)&0xf)<<8
}
} else if a.Type == obj.TYPE_REGREG || a.Type == obj.TYPE_REGREG2 {
if a.Offset == int64(v.Reg) {
a.Offset = int64(s.Reg)
}
if a.Reg == v.Reg {
a.Reg = s.Reg
}
} else {
a.Reg = s.Reg
}
}
}
return 0
}
func copysub1(p1 *obj.Prog, v *obj.Addr, s *obj.Addr, f int) int {
if f != 0 {
if copyau1(p1, v) {
p1.Reg = s.Reg
}
}
return 0
}
var predinfo = []struct {
opcode int
notopcode int
scond int
notscond int
}{
struct {
opcode int
notopcode int
scond int
notscond int
}{arm.ABEQ, arm.ABNE, 0x0, 0x1},
struct {
opcode int
notopcode int
scond int
notscond int
}{arm.ABNE, arm.ABEQ, 0x1, 0x0},
struct {
opcode int
notopcode int
scond int
notscond int
}{arm.ABCS, arm.ABCC, 0x2, 0x3},
struct {
opcode int
notopcode int
scond int
notscond int
}{arm.ABHS, arm.ABLO, 0x2, 0x3},
struct {
opcode int
notopcode int
scond int
notscond int
}{arm.ABCC, arm.ABCS, 0x3, 0x2},
struct {
opcode int
notopcode int
scond int
notscond int
}{arm.ABLO, arm.ABHS, 0x3, 0x2},
struct {
opcode int
notopcode int
scond int
notscond int
}{arm.ABMI, arm.ABPL, 0x4, 0x5},
struct {
opcode int
notopcode int
scond int
notscond int
}{arm.ABPL, arm.ABMI, 0x5, 0x4},
struct {
opcode int
notopcode int
scond int
notscond int
}{arm.ABVS, arm.ABVC, 0x6, 0x7},
struct {
opcode int
notopcode int
scond int
notscond int
}{arm.ABVC, arm.ABVS, 0x7, 0x6},
struct {
opcode int
notopcode int
scond int
notscond int
}{arm.ABHI, arm.ABLS, 0x8, 0x9},
struct {
opcode int
notopcode int
scond int
notscond int
}{arm.ABLS, arm.ABHI, 0x9, 0x8},
struct {
opcode int
notopcode int
scond int
notscond int
}{arm.ABGE, arm.ABLT, 0xA, 0xB},
struct {
opcode int
notopcode int
scond int
notscond int
}{arm.ABLT, arm.ABGE, 0xB, 0xA},
struct {
opcode int
notopcode int
scond int
notscond int
}{arm.ABGT, arm.ABLE, 0xC, 0xD},
struct {
opcode int
notopcode int
scond int
notscond int
}{arm.ABLE, arm.ABGT, 0xD, 0xC},
}
type Joininfo struct {
start *gc.Flow
last *gc.Flow
end *gc.Flow
len int
}
const (
Join = iota
Split
End
Branch
Setcond
Toolong
)
const (
Falsecond = iota
Truecond
Delbranch
Keepbranch
)
func isbranch(p *obj.Prog) bool {
return (arm.ABEQ <= p.As) && (p.As <= arm.ABLE)
}
func predicable(p *obj.Prog) bool {
switch p.As {
case obj.ANOP,
obj.AXXX,
obj.ADATA,
obj.AGLOBL,
obj.ATEXT,
arm.AWORD,
arm.ABCASE,
arm.ACASE:
return false
}
if isbranch(p) {
return false
}
return true
}
/*
* Depends on an analysis of the encodings performed by 5l.
* These seem to be all of the opcodes that lead to the "S" bit
* being set in the instruction encodings.
*
* C_SBIT may also have been set explicitly in p->scond.
*/
func modifiescpsr(p *obj.Prog) bool {
switch p.As {
case arm.AMULLU,
arm.AMULA,
arm.AMULU,
arm.ADIVU,
arm.ATEQ,
arm.ACMN,
arm.ATST,
arm.ACMP,
arm.AMUL,
arm.ADIV,
arm.AMOD,
arm.AMODU,
arm.ABL:
return true
}
if p.Scond&arm.C_SBIT != 0 {
return true
}
return false
}
/*
* Find the maximal chain of instructions starting with r which could
* be executed conditionally
*/
func joinsplit(r *gc.Flow, j *Joininfo) int {
j.start = r
j.last = r
j.len = 0
for {
if r.P2 != nil && (r.P1 != nil || r.P2.P2link != nil) {
j.end = r
return Join
}
if r.S1 != nil && r.S2 != nil {
j.end = r
return Split
}
j.last = r
if r.Prog.As != obj.ANOP {
j.len++
}
if r.S1 == nil && r.S2 == nil {
j.end = r.Link
return End
}
if r.S2 != nil {
j.end = r.S2
return Branch
}
if modifiescpsr(r.Prog) {
j.end = r.S1
return Setcond
}
r = r.S1
if j.len >= 4 {
break
}
}
j.end = r
return Toolong
}
func successor(r *gc.Flow) *gc.Flow {
if r.S1 != nil {
return r.S1
} else {
return r.S2
}
}
func applypred(rstart *gc.Flow, j *Joininfo, cond int, branch int) {
if j.len == 0 {
return
}
var pred int
if cond == Truecond {
pred = predinfo[rstart.Prog.As-arm.ABEQ].scond
} else {
pred = predinfo[rstart.Prog.As-arm.ABEQ].notscond
}
for r := (*gc.Flow)(j.start); ; r = successor(r) {
if r.Prog.As == arm.AB {
if r != j.last || branch == Delbranch {
excise(r)
} else {
if cond == Truecond {
r.Prog.As = int16(predinfo[rstart.Prog.As-arm.ABEQ].opcode)
} else {
r.Prog.As = int16(predinfo[rstart.Prog.As-arm.ABEQ].notopcode)
}
}
} else if predicable(r.Prog) {
r.Prog.Scond = uint8(int(r.Prog.Scond&^arm.C_SCOND) | pred)
}
if r.S1 != r.Link {
r.S1 = r.Link
r.Link.P1 = r
}
if r == j.last {
break
}
}
}
func predicate(g *gc.Graph) {
var t1 int
var t2 int
var j1 Joininfo
var j2 Joininfo
for r := (*gc.Flow)(g.Start); r != nil; r = r.Link {
if isbranch(r.Prog) {
t1 = joinsplit(r.S1, &j1)
t2 = joinsplit(r.S2, &j2)
if j1.last.Link != j2.start {
continue
}
if j1.end == j2.end {
if (t1 == Branch && (t2 == Join || t2 == Setcond)) || (t2 == Join && (t1 == Join || t1 == Setcond)) {
applypred(r, &j1, Falsecond, Delbranch)
applypred(r, &j2, Truecond, Delbranch)
excise(r)
continue
}
}
if t1 == End || t1 == Branch {
applypred(r, &j1, Falsecond, Keepbranch)
excise(r)
continue
}
}
}
}
func isdconst(a *obj.Addr) bool {
return a.Type == obj.TYPE_CONST
}
func isfloatreg(a *obj.Addr) bool {
return arm.REG_F0 <= a.Reg && a.Reg <= arm.REG_F15
}
func stackaddr(a *obj.Addr) bool {
return regtyp(a) && a.Reg == arm.REGSP
}
func smallindir(a *obj.Addr, reg *obj.Addr) bool {
return reg.Type == obj.TYPE_REG && a.Type == obj.TYPE_MEM && a.Reg == reg.Reg && 0 <= a.Offset && a.Offset < 4096
}
func excise(r *gc.Flow) {
p := (*obj.Prog)(r.Prog)
obj.Nopout(p)
}