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go/src/cmd/internal/obj/i386/obj8.go
Russ Cox 79f727a70e cmd/5g etc: mechanical cleanup 
Run rsc.io/grind rev a26569f on C->Go conversions.

The new change in grind is the inlining of goto targets.
If code says 'goto x' and the block starting at label x is unreachable
except through that goto and the code can be moved to where
the goto is without changing the meaning of its variable names,
grind does that move. Simlarly, a goto to a plain return statement
turns into that return statement (even if there are other paths to
the return statement).

Combined, these remove many long-distance gotos, which in turn
makes it possible to reduce the scope of more variable declarations.
(Because gotos can't jump across declarations, the gotos were
keeping the declarations from moving.)

Checked bit-for-bit compatibility with toolstash + buildall.

Reduces compiler runtime in html/template by about 12%.

Change-Id: Id727c0bd7763a61aa22f3daa00aeb8fccbc057a3
Reviewed-on: https://go-review.googlesource.com/6472
Reviewed-by: Aram Hăvărneanu <aram@mgk.ro>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
2015-03-02 18:40:28 +00:00

902 lines
19 KiB
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// Inferno utils/8l/pass.c
// http://code.google.com/p/inferno-os/source/browse/utils/8l/pass.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 i386
import (
"cmd/internal/obj"
"encoding/binary"
"fmt"
"log"
"math"
)
func canuselocaltls(ctxt *obj.Link) bool {
switch ctxt.Headtype {
case obj.Hlinux,
obj.Hnacl,
obj.Hplan9,
obj.Hwindows:
return false
}
return true
}
func progedit(ctxt *obj.Link, p *obj.Prog) {
// See obj6.c for discussion of TLS.
if canuselocaltls(ctxt) {
// Reduce TLS initial exec model to TLS local exec model.
// Sequences like
// MOVL TLS, BX
// ... off(BX)(TLS*1) ...
// become
// NOP
// ... off(TLS) ...
if p.As == AMOVL && p.From.Type == obj.TYPE_REG && p.From.Reg == REG_TLS && p.To.Type == obj.TYPE_REG && REG_AX <= p.To.Reg && p.To.Reg <= REG_DI {
p.As = obj.ANOP
p.From.Type = obj.TYPE_NONE
p.To.Type = obj.TYPE_NONE
}
if p.From.Type == obj.TYPE_MEM && p.From.Index == REG_TLS && REG_AX <= p.From.Reg && p.From.Reg <= REG_DI {
p.From.Type = obj.TYPE_MEM
p.From.Reg = REG_TLS
p.From.Scale = 0
p.From.Index = REG_NONE
}
if p.To.Type == obj.TYPE_MEM && p.To.Index == REG_TLS && REG_AX <= p.To.Reg && p.To.Reg <= REG_DI {
p.To.Type = obj.TYPE_MEM
p.To.Reg = REG_TLS
p.To.Scale = 0
p.To.Index = REG_NONE
}
} else {
// As a courtesy to the C compilers, rewrite TLS local exec load as TLS initial exec load.
// The instruction
// MOVL off(TLS), BX
// becomes the sequence
// MOVL TLS, BX
// MOVL off(BX)(TLS*1), BX
// This allows the C compilers to emit references to m and g using the direct off(TLS) form.
if p.As == AMOVL && p.From.Type == obj.TYPE_MEM && p.From.Reg == REG_TLS && p.To.Type == obj.TYPE_REG && REG_AX <= p.To.Reg && p.To.Reg <= REG_DI {
q := obj.Appendp(ctxt, p)
q.As = p.As
q.From.Type = obj.TYPE_MEM
q.From.Reg = p.To.Reg
q.From.Index = REG_TLS
q.From.Scale = 2 // TODO: use 1
q.To = p.To
p.From.Type = obj.TYPE_REG
p.From.Reg = REG_TLS
p.From.Index = REG_NONE
p.From.Offset = 0
}
}
// TODO: Remove.
if ctxt.Headtype == obj.Hplan9 {
if p.From.Scale == 1 && p.From.Index == REG_TLS {
p.From.Scale = 2
}
if p.To.Scale == 1 && p.To.Index == REG_TLS {
p.To.Scale = 2
}
}
// Rewrite CALL/JMP/RET to symbol as TYPE_BRANCH.
switch p.As {
case obj.ACALL,
obj.AJMP,
obj.ARET:
if p.To.Type == obj.TYPE_MEM && (p.To.Name == obj.NAME_EXTERN || p.To.Name == obj.NAME_STATIC) && p.To.Sym != nil {
p.To.Type = obj.TYPE_BRANCH
}
}
// Rewrite float constants to values stored in memory.
switch p.As {
// Convert AMOVSS $(0), Xx to AXORPS Xx, Xx
case AMOVSS:
if p.From.Type == obj.TYPE_FCONST {
if p.From.U.Dval == 0 {
if p.To.Type == obj.TYPE_REG && REG_X0 <= p.To.Reg && p.To.Reg <= REG_X7 {
p.As = AXORPS
p.From = p.To
break
}
}
}
fallthrough
// fallthrough
case AFMOVF,
AFADDF,
AFSUBF,
AFSUBRF,
AFMULF,
AFDIVF,
AFDIVRF,
AFCOMF,
AFCOMFP,
AADDSS,
ASUBSS,
AMULSS,
ADIVSS,
ACOMISS,
AUCOMISS:
if p.From.Type == obj.TYPE_FCONST {
f32 := float32(p.From.U.Dval)
i32 := math.Float32bits(f32)
literal := fmt.Sprintf("$f32.%08x", i32)
s := obj.Linklookup(ctxt, literal, 0)
if s.Type == 0 {
s.Type = obj.SRODATA
obj.Adduint32(ctxt, s, i32)
s.Reachable = 0
}
p.From.Type = obj.TYPE_MEM
p.From.Name = obj.NAME_EXTERN
p.From.Sym = s
p.From.Offset = 0
}
// Convert AMOVSD $(0), Xx to AXORPS Xx, Xx
case AMOVSD:
if p.From.Type == obj.TYPE_FCONST {
if p.From.U.Dval == 0 {
if p.To.Type == obj.TYPE_REG && REG_X0 <= p.To.Reg && p.To.Reg <= REG_X7 {
p.As = AXORPS
p.From = p.To
break
}
}
}
fallthrough
// fallthrough
case AFMOVD,
AFADDD,
AFSUBD,
AFSUBRD,
AFMULD,
AFDIVD,
AFDIVRD,
AFCOMD,
AFCOMDP,
AADDSD,
ASUBSD,
AMULSD,
ADIVSD,
ACOMISD,
AUCOMISD:
if p.From.Type == obj.TYPE_FCONST {
i64 := math.Float64bits(p.From.U.Dval)
literal := fmt.Sprintf("$f64.%016x", i64)
s := obj.Linklookup(ctxt, literal, 0)
if s.Type == 0 {
s.Type = obj.SRODATA
obj.Adduint64(ctxt, s, i64)
s.Reachable = 0
}
p.From.Type = obj.TYPE_MEM
p.From.Name = obj.NAME_EXTERN
p.From.Sym = s
p.From.Offset = 0
}
}
}
func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
if ctxt.Symmorestack[0] == nil {
ctxt.Symmorestack[0] = obj.Linklookup(ctxt, "runtime.morestack", 0)
ctxt.Symmorestack[1] = obj.Linklookup(ctxt, "runtime.morestack_noctxt", 0)
}
if ctxt.Headtype == obj.Hplan9 && ctxt.Plan9privates == nil {
ctxt.Plan9privates = obj.Linklookup(ctxt, "_privates", 0)
}
ctxt.Cursym = cursym
if cursym.Text == nil || cursym.Text.Link == nil {
return
}
p := cursym.Text
autoffset := int32(p.To.Offset)
if autoffset < 0 {
autoffset = 0
}
cursym.Locals = autoffset
cursym.Args = p.To.U.Argsize
q := (*obj.Prog)(nil)
if p.From3.Offset&obj.NOSPLIT == 0 || (p.From3.Offset&obj.WRAPPER != 0) {
p = obj.Appendp(ctxt, p)
p = load_g_cx(ctxt, p) // load g into CX
}
if cursym.Text.From3.Offset&obj.NOSPLIT == 0 {
p = stacksplit(ctxt, p, autoffset, cursym.Text.From3.Offset&obj.NEEDCTXT == 0, &q) // emit split check
}
if autoffset != 0 {
p = obj.Appendp(ctxt, p)
p.As = AADJSP
p.From.Type = obj.TYPE_CONST
p.From.Offset = int64(autoffset)
p.Spadj = autoffset
} else {
// zero-byte stack adjustment.
// Insert a fake non-zero adjustment so that stkcheck can
// recognize the end of the stack-splitting prolog.
p = obj.Appendp(ctxt, p)
p.As = obj.ANOP
p.Spadj = int32(-ctxt.Arch.Ptrsize)
p = obj.Appendp(ctxt, p)
p.As = obj.ANOP
p.Spadj = int32(ctxt.Arch.Ptrsize)
}
if q != nil {
q.Pcond = p
}
deltasp := autoffset
if cursym.Text.From3.Offset&obj.WRAPPER != 0 {
// if(g->panic != nil && g->panic->argp == FP) g->panic->argp = bottom-of-frame
//
// MOVL g_panic(CX), BX
// TESTL BX, BX
// JEQ end
// LEAL (autoffset+4)(SP), DI
// CMPL panic_argp(BX), DI
// JNE end
// MOVL SP, panic_argp(BX)
// end:
// NOP
//
// The NOP is needed to give the jumps somewhere to land.
// It is a liblink NOP, not an x86 NOP: it encodes to 0 instruction bytes.
p = obj.Appendp(ctxt, p)
p.As = AMOVL
p.From.Type = obj.TYPE_MEM
p.From.Reg = REG_CX
p.From.Offset = 4 * int64(ctxt.Arch.Ptrsize) // G.panic
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_BX
p = obj.Appendp(ctxt, p)
p.As = ATESTL
p.From.Type = obj.TYPE_REG
p.From.Reg = REG_BX
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_BX
p = obj.Appendp(ctxt, p)
p.As = AJEQ
p.To.Type = obj.TYPE_BRANCH
p1 := p
p = obj.Appendp(ctxt, p)
p.As = ALEAL
p.From.Type = obj.TYPE_MEM
p.From.Reg = REG_SP
p.From.Offset = int64(autoffset) + 4
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_DI
p = obj.Appendp(ctxt, p)
p.As = ACMPL
p.From.Type = obj.TYPE_MEM
p.From.Reg = REG_BX
p.From.Offset = 0 // Panic.argp
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_DI
p = obj.Appendp(ctxt, p)
p.As = AJNE
p.To.Type = obj.TYPE_BRANCH
p2 := p
p = obj.Appendp(ctxt, p)
p.As = AMOVL
p.From.Type = obj.TYPE_REG
p.From.Reg = REG_SP
p.To.Type = obj.TYPE_MEM
p.To.Reg = REG_BX
p.To.Offset = 0 // Panic.argp
p = obj.Appendp(ctxt, p)
p.As = obj.ANOP
p1.Pcond = p
p2.Pcond = p
}
if ctxt.Debugzerostack != 0 && autoffset != 0 && cursym.Text.From3.Offset&obj.NOSPLIT == 0 {
// 8l -Z means zero the stack frame on entry.
// This slows down function calls but can help avoid
// false positives in garbage collection.
p = obj.Appendp(ctxt, p)
p.As = AMOVL
p.From.Type = obj.TYPE_REG
p.From.Reg = REG_SP
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_DI
p = obj.Appendp(ctxt, p)
p.As = AMOVL
p.From.Type = obj.TYPE_CONST
p.From.Offset = int64(autoffset) / 4
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_CX
p = obj.Appendp(ctxt, p)
p.As = AMOVL
p.From.Type = obj.TYPE_CONST
p.From.Offset = 0
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_AX
p = obj.Appendp(ctxt, p)
p.As = AREP
p = obj.Appendp(ctxt, p)
p.As = ASTOSL
}
var a int
for ; p != nil; p = p.Link {
a = int(p.From.Name)
if a == obj.NAME_AUTO {
p.From.Offset += int64(deltasp)
}
if a == obj.NAME_PARAM {
p.From.Offset += int64(deltasp) + 4
}
a = int(p.To.Name)
if a == obj.NAME_AUTO {
p.To.Offset += int64(deltasp)
}
if a == obj.NAME_PARAM {
p.To.Offset += int64(deltasp) + 4
}
switch p.As {
default:
continue
case APUSHL,
APUSHFL:
deltasp += 4
p.Spadj = 4
continue
case APUSHW,
APUSHFW:
deltasp += 2
p.Spadj = 2
continue
case APOPL,
APOPFL:
deltasp -= 4
p.Spadj = -4
continue
case APOPW,
APOPFW:
deltasp -= 2
p.Spadj = -2
continue
case obj.ARET:
break
}
if autoffset != deltasp {
ctxt.Diag("unbalanced PUSH/POP")
}
if autoffset != 0 {
p.As = AADJSP
p.From.Type = obj.TYPE_CONST
p.From.Offset = int64(-autoffset)
p.Spadj = -autoffset
p = obj.Appendp(ctxt, p)
p.As = obj.ARET
// If there are instructions following
// this ARET, they come from a branch
// with the same stackframe, so undo
// the cleanup.
p.Spadj = +autoffset
}
if p.To.Sym != nil { // retjmp
p.As = obj.AJMP
}
}
}
// Append code to p to load g into cx.
// Overwrites p with the first instruction (no first appendp).
// Overwriting p is unusual but it lets use this in both the
// prologue (caller must call appendp first) and in the epilogue.
// Returns last new instruction.
func load_g_cx(ctxt *obj.Link, p *obj.Prog) *obj.Prog {
p.As = AMOVL
p.From.Type = obj.TYPE_MEM
p.From.Reg = REG_TLS
p.From.Offset = 0
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_CX
next := p.Link
progedit(ctxt, p)
for p.Link != next {
p = p.Link
}
if p.From.Index == REG_TLS {
p.From.Scale = 2
}
return p
}
// Append code to p to check for stack split.
// Appends to (does not overwrite) p.
// Assumes g is in CX.
// Returns last new instruction.
// On return, *jmpok is the instruction that should jump
// to the stack frame allocation if no split is needed.
func stacksplit(ctxt *obj.Link, p *obj.Prog, framesize int32, noctxt bool, jmpok **obj.Prog) *obj.Prog {
if ctxt.Debugstack != 0 {
// 8l -K means check not only for stack
// overflow but stack underflow.
// On underflow, INT 3 (breakpoint).
// Underflow itself is rare but this also
// catches out-of-sync stack guard info.
p = obj.Appendp(ctxt, p)
p.As = ACMPL
p.From.Type = obj.TYPE_MEM
p.From.Reg = REG_CX
p.From.Offset = 4
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_SP
p = obj.Appendp(ctxt, p)
p.As = AJCC
p.To.Type = obj.TYPE_BRANCH
p.To.Offset = 4
q1 := p
p = obj.Appendp(ctxt, p)
p.As = AINT
p.From.Type = obj.TYPE_CONST
p.From.Offset = 3
p = obj.Appendp(ctxt, p)
p.As = obj.ANOP
q1.Pcond = p
}
q1 := (*obj.Prog)(nil)
if framesize <= obj.StackSmall {
// small stack: SP <= stackguard
// CMPL SP, stackguard
p = obj.Appendp(ctxt, p)
p.As = ACMPL
p.From.Type = obj.TYPE_REG
p.From.Reg = REG_SP
p.To.Type = obj.TYPE_MEM
p.To.Reg = REG_CX
p.To.Offset = 2 * int64(ctxt.Arch.Ptrsize) // G.stackguard0
if ctxt.Cursym.Cfunc != 0 {
p.To.Offset = 3 * int64(ctxt.Arch.Ptrsize) // G.stackguard1
}
} else if framesize <= obj.StackBig {
// large stack: SP-framesize <= stackguard-StackSmall
// LEAL -(framesize-StackSmall)(SP), AX
// CMPL AX, stackguard
p = obj.Appendp(ctxt, p)
p.As = ALEAL
p.From.Type = obj.TYPE_MEM
p.From.Reg = REG_SP
p.From.Offset = -(int64(framesize) - obj.StackSmall)
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_AX
p = obj.Appendp(ctxt, p)
p.As = ACMPL
p.From.Type = obj.TYPE_REG
p.From.Reg = REG_AX
p.To.Type = obj.TYPE_MEM
p.To.Reg = REG_CX
p.To.Offset = 2 * int64(ctxt.Arch.Ptrsize) // G.stackguard0
if ctxt.Cursym.Cfunc != 0 {
p.To.Offset = 3 * int64(ctxt.Arch.Ptrsize) // G.stackguard1
}
} else {
// Such a large stack we need to protect against wraparound
// if SP is close to zero.
// SP-stackguard+StackGuard <= framesize + (StackGuard-StackSmall)
// The +StackGuard on both sides is required to keep the left side positive:
// SP is allowed to be slightly below stackguard. See stack.h.
//
// Preemption sets stackguard to StackPreempt, a very large value.
// That breaks the math above, so we have to check for that explicitly.
// MOVL stackguard, CX
// CMPL CX, $StackPreempt
// JEQ label-of-call-to-morestack
// LEAL StackGuard(SP), AX
// SUBL stackguard, AX
// CMPL AX, $(framesize+(StackGuard-StackSmall))
p = obj.Appendp(ctxt, p)
p.As = AMOVL
p.From.Type = obj.TYPE_MEM
p.From.Reg = REG_CX
p.From.Offset = 0
p.From.Offset = 2 * int64(ctxt.Arch.Ptrsize) // G.stackguard0
if ctxt.Cursym.Cfunc != 0 {
p.From.Offset = 3 * int64(ctxt.Arch.Ptrsize) // G.stackguard1
}
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_SI
p = obj.Appendp(ctxt, p)
p.As = ACMPL
p.From.Type = obj.TYPE_REG
p.From.Reg = REG_SI
p.To.Type = obj.TYPE_CONST
p.To.Offset = int64(uint32(obj.StackPreempt & (1<<32 - 1)))
p = obj.Appendp(ctxt, p)
p.As = AJEQ
p.To.Type = obj.TYPE_BRANCH
q1 = p
p = obj.Appendp(ctxt, p)
p.As = ALEAL
p.From.Type = obj.TYPE_MEM
p.From.Reg = REG_SP
p.From.Offset = obj.StackGuard
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_AX
p = obj.Appendp(ctxt, p)
p.As = ASUBL
p.From.Type = obj.TYPE_REG
p.From.Reg = REG_SI
p.From.Offset = 0
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_AX
p = obj.Appendp(ctxt, p)
p.As = ACMPL
p.From.Type = obj.TYPE_REG
p.From.Reg = REG_AX
p.To.Type = obj.TYPE_CONST
p.To.Offset = int64(framesize) + (obj.StackGuard - obj.StackSmall)
}
// common
p = obj.Appendp(ctxt, p)
p.As = AJHI
p.To.Type = obj.TYPE_BRANCH
p.To.Offset = 4
q := p
p = obj.Appendp(ctxt, p)
p.As = obj.ACALL
p.To.Type = obj.TYPE_BRANCH
if ctxt.Cursym.Cfunc != 0 {
p.To.Sym = obj.Linklookup(ctxt, "runtime.morestackc", 0)
} else {
p.To.Sym = ctxt.Symmorestack[bool2int(noctxt)]
}
p = obj.Appendp(ctxt, p)
p.As = obj.AJMP
p.To.Type = obj.TYPE_BRANCH
p.Pcond = ctxt.Cursym.Text.Link
if q != nil {
q.Pcond = p.Link
}
if q1 != nil {
q1.Pcond = q.Link
}
*jmpok = q
return p
}
func follow(ctxt *obj.Link, s *obj.LSym) {
ctxt.Cursym = s
firstp := ctxt.NewProg()
lastp := firstp
xfol(ctxt, s.Text, &lastp)
lastp.Link = nil
s.Text = firstp.Link
}
func nofollow(a int) bool {
switch a {
case obj.AJMP,
obj.ARET,
AIRETL,
AIRETW,
obj.AUNDEF:
return true
}
return false
}
func pushpop(a int) bool {
switch a {
case APUSHL,
APUSHFL,
APUSHW,
APUSHFW,
APOPL,
APOPFL,
APOPW,
APOPFW:
return true
}
return false
}
func relinv(a int) int {
switch a {
case AJEQ:
return AJNE
case AJNE:
return AJEQ
case AJLE:
return AJGT
case AJLS:
return AJHI
case AJLT:
return AJGE
case AJMI:
return AJPL
case AJGE:
return AJLT
case AJPL:
return AJMI
case AJGT:
return AJLE
case AJHI:
return AJLS
case AJCS:
return AJCC
case AJCC:
return AJCS
case AJPS:
return AJPC
case AJPC:
return AJPS
case AJOS:
return AJOC
case AJOC:
return AJOS
}
log.Fatalf("unknown relation: %s", Anames[a])
return 0
}
func xfol(ctxt *obj.Link, p *obj.Prog, last **obj.Prog) {
var q *obj.Prog
var i int
var a int
loop:
if p == nil {
return
}
if p.As == obj.AJMP {
q = p.Pcond
if q != nil && q.As != obj.ATEXT {
/* mark instruction as done and continue layout at target of jump */
p.Mark = 1
p = q
if p.Mark == 0 {
goto loop
}
}
}
if p.Mark != 0 {
/*
* p goes here, but already used it elsewhere.
* copy up to 4 instructions or else branch to other copy.
*/
i = 0
q = p
for ; i < 4; (func() { i++; q = q.Link })() {
if q == nil {
break
}
if q == *last {
break
}
a = int(q.As)
if a == obj.ANOP {
i--
continue
}
if nofollow(a) || pushpop(a) {
break // NOTE(rsc): arm does goto copy
}
if q.Pcond == nil || q.Pcond.Mark != 0 {
continue
}
if a == obj.ACALL || a == ALOOP {
continue
}
for {
if p.As == obj.ANOP {
p = p.Link
continue
}
q = obj.Copyp(ctxt, p)
p = p.Link
q.Mark = 1
(*last).Link = q
*last = q
if int(q.As) != a || q.Pcond == nil || q.Pcond.Mark != 0 {
continue
}
q.As = int16(relinv(int(q.As)))
p = q.Pcond
q.Pcond = q.Link
q.Link = p
xfol(ctxt, q.Link, last)
p = q.Link
if p.Mark != 0 {
return
}
goto loop
/* */
}
}
q = ctxt.NewProg()
q.As = obj.AJMP
q.Lineno = p.Lineno
q.To.Type = obj.TYPE_BRANCH
q.To.Offset = p.Pc
q.Pcond = p
p = q
}
/* emit p */
p.Mark = 1
(*last).Link = p
*last = p
a = int(p.As)
/* continue loop with what comes after p */
if nofollow(a) {
return
}
if p.Pcond != nil && a != obj.ACALL {
/*
* some kind of conditional branch.
* recurse to follow one path.
* continue loop on the other.
*/
q = obj.Brchain(ctxt, p.Pcond)
if q != nil {
p.Pcond = q
}
q = obj.Brchain(ctxt, p.Link)
if q != nil {
p.Link = q
}
if p.From.Type == obj.TYPE_CONST {
if p.From.Offset == 1 {
/*
* expect conditional jump to be taken.
* rewrite so that's the fall-through case.
*/
p.As = int16(relinv(a))
q = p.Link
p.Link = p.Pcond
p.Pcond = q
}
} else {
q = p.Link
if q.Mark != 0 {
if a != ALOOP {
p.As = int16(relinv(a))
p.Link = p.Pcond
p.Pcond = q
}
}
}
xfol(ctxt, p.Link, last)
if p.Pcond.Mark != 0 {
return
}
p = p.Pcond
goto loop
}
p = p.Link
goto loop
}
var Link386 = obj.LinkArch{
Rconv: Rconv,
ByteOrder: binary.LittleEndian,
Pconv: Pconv,
Name: "386",
Thechar: '8',
Preprocess: preprocess,
Assemble: span8,
Follow: follow,
Progedit: progedit,
Minlc: 1,
Ptrsize: 4,
Regsize: 4,
}
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