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go/src/cmd/internal/obj/x86/obj6.go
Russ Cox 1fc330d8fe [dev.cc] cmd/internal/obj: reconvert from liblink 
cmd/internal/obj reconverted using rsc.io/c2go rev 2a95256.

- Brings in new, more regular Prog, Addr definitions

- Add Prog* argument to oclass in liblink/asm[68].c, for c2go conversion.
- Update objwriter for change in TEXT size encoding.
- Merge 5a, 6a, 8a, 9a changes into new5a, new6a, new8a, new9a (by hand).

- Add +build ignore to cmd/asm/internal/{addr,arch,asm}, cmd/asm.
  They need to be updated for the changes.

- Reenable verifyAsm in cmd/go.
- Reenable GOOBJ=2 mode by default in liblink.

All architectures build successfully again.

Change-Id: I2c845c5d365aa484b570476898171bee657b626d
Reviewed-on: https://go-review.googlesource.com/3963
Reviewed-by: Rob Pike <r@golang.org>
2015-02-05 19:13:12 +00:00

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// Inferno utils/6l/pass.c
// http://code.google.com/p/inferno-os/source/browse/utils/6l/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 x86
import (
"cmd/internal/obj"
"encoding/binary"
"fmt"
"log"
"math"
)
func nopout(p *obj.Prog) {
p.As = obj.ANOP
p.From.Type = obj.TYPE_NONE
p.From.Reg = 0
p.From.Name = 0
p.To.Type = obj.TYPE_NONE
p.To.Reg = 0
p.To.Name = 0
}
func canuselocaltls(ctxt *obj.Link) int {
switch ctxt.Headtype {
case obj.Hplan9,
obj.Hwindows:
return 0
}
return 1
}
func progedit(ctxt *obj.Link, p *obj.Prog) {
var literal string
var s *obj.LSym
var q *obj.Prog
// Thread-local storage references use the TLS pseudo-register.
// As a register, TLS refers to the thread-local storage base, and it
// can only be loaded into another register:
//
// MOVQ TLS, AX
//
// An offset from the thread-local storage base is written off(reg)(TLS*1).
// Semantically it is off(reg), but the (TLS*1) annotation marks this as
// indexing from the loaded TLS base. This emits a relocation so that
// if the linker needs to adjust the offset, it can. For example:
//
// MOVQ TLS, AX
// MOVQ 8(AX)(TLS*1), CX // load m into CX
//
// On systems that support direct access to the TLS memory, this
// pair of instructions can be reduced to a direct TLS memory reference:
//
// MOVQ 8(TLS), CX // load m into CX
//
// The 2-instruction and 1-instruction forms correspond roughly to
// ELF TLS initial exec mode and ELF TLS local exec mode, respectively.
//
// We applies this rewrite on systems that support the 1-instruction form.
// The decision is made using only the operating system (and probably
// the -shared flag, eventually), not the link mode. If some link modes
// on a particular operating system require the 2-instruction form,
// then all builds for that operating system will use the 2-instruction
// form, so that the link mode decision can be delayed to link time.
//
// In this way, all supported systems use identical instructions to
// access TLS, and they are rewritten appropriately first here in
// liblink and then finally using relocations in the linker.
if canuselocaltls(ctxt) != 0 {
// Reduce TLS initial exec model to TLS local exec model.
// Sequences like
// MOVQ TLS, BX
// ... off(BX)(TLS*1) ...
// become
// NOP
// ... off(TLS) ...
//
// TODO(rsc): Remove the Hsolaris special case. It exists only to
// guarantee we are producing byte-identical binaries as before this code.
// But it should be unnecessary.
if (p.As == AMOVQ || 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_R15 && ctxt.Headtype != obj.Hsolaris {
nopout(p)
}
if p.From.Type == obj.TYPE_MEM && p.From.Index == REG_TLS && REG_AX <= p.From.Reg && p.From.Reg <= REG_R15 {
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_R15 {
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
// MOVQ off(TLS), BX
// becomes the sequence
// MOVQ TLS, BX
// MOVQ 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 == AMOVQ || 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_R15 {
q = obj.Appendp(ctxt, p)
q.As = p.As
q.From = p.From
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.Hwindows || 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
}
}
if ctxt.Headtype == obj.Hnacl {
nacladdr(ctxt, p, &p.From)
nacladdr(ctxt, p, &p.To)
}
// Maintain information about code generation mode.
if ctxt.Mode == 0 {
ctxt.Mode = 64
}
p.Mode = int8(ctxt.Mode)
switch p.As {
case AMODE:
if p.From.Type == obj.TYPE_CONST || (p.From.Type == obj.TYPE_MEM && p.From.Reg == REG_NONE) {
switch int(p.From.Offset) {
case 16,
32,
64:
ctxt.Mode = int(p.From.Offset)
break
}
}
nopout(p)
break
}
// 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
}
break
}
// Rewrite float constants to values stored in memory.
switch p.As {
// Convert AMOVSS $(0), Xx to AXORPS Xx, Xx
case AMOVSS:
if p.From.Type == obj.TYPE_FCONST {
if p.From.U.Dval == 0 {
if p.To.Type == obj.TYPE_REG && REG_X0 <= p.To.Reg && p.To.Reg <= REG_X15 {
p.As = AXORPS
p.From = p.To
break
}
}
}
fallthrough
// fallthrough
case AFMOVF,
AFADDF,
AFSUBF,
AFSUBRF,
AFMULF,
AFDIVF,
AFDIVRF,
AFCOMF,
AFCOMFP,
AADDSS,
ASUBSS,
AMULSS,
ADIVSS,
ACOMISS,
AUCOMISS:
if p.From.Type == obj.TYPE_FCONST {
var i32 uint32
var f32 float32
f32 = float32(p.From.U.Dval)
i32 = math.Float32bits(f32)
literal = fmt.Sprintf("$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 $(0), Xx to AXORPS Xx, Xx
case AMOVSD:
if p.From.Type == obj.TYPE_FCONST {
if p.From.U.Dval == 0 {
if p.To.Type == obj.TYPE_REG && REG_X0 <= p.To.Reg && p.To.Reg <= REG_X15 {
p.As = AXORPS
p.From = p.To
break
}
}
}
fallthrough
// fallthrough
case AFMOVD,
AFADDD,
AFSUBD,
AFSUBRD,
AFMULD,
AFDIVD,
AFDIVRD,
AFCOMD,
AFCOMDP,
AADDSD,
ASUBSD,
AMULSD,
ADIVSD,
ACOMISD,
AUCOMISD:
if p.From.Type == obj.TYPE_FCONST {
var i64 uint64
i64 = math.Float64bits(p.From.U.Dval)
literal = fmt.Sprintf("$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
}
break
}
}
func nacladdr(ctxt *obj.Link, p *obj.Prog, a *obj.Addr) {
if p.As == ALEAL || p.As == ALEAQ {
return
}
if a.Reg == REG_BP {
ctxt.Diag("invalid address: %v", p)
return
}
if a.Reg == REG_TLS {
a.Reg = REG_BP
}
if a.Type == obj.TYPE_MEM && a.Name == obj.NAME_NONE {
switch a.Reg {
// all ok
case REG_BP,
REG_SP,
REG_R15:
break
default:
if a.Index != REG_NONE {
ctxt.Diag("invalid address %v", p)
}
a.Index = a.Reg
if a.Index != REG_NONE {
a.Scale = 1
}
a.Reg = REG_R15
break
}
}
}
func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
var p *obj.Prog
var q *obj.Prog
var p1 *obj.Prog
var p2 *obj.Prog
var autoffset int32
var deltasp int32
var a int
var pcsize int
var bpsize int
var textarg int64
if ctxt.Tlsg == nil {
ctxt.Tlsg = obj.Linklookup(ctxt, "runtime.tlsg", 0)
}
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
}
if obj.Framepointer_enabled != 0 && autoffset > 0 {
// Make room for to save a base pointer. If autoffset == 0,
// this might do something special like a tail jump to
// another function, so in that case we omit this.
bpsize = ctxt.Arch.Ptrsize
autoffset += int32(bpsize)
p.To.Offset += int64(bpsize)
} else {
bpsize = 0
}
textarg = int64(p.To.U.Argsize)
cursym.Args = int32(textarg)
cursym.Locals = int32(p.To.Offset)
if autoffset < obj.StackSmall && !(p.From3.Offset&obj.NOSPLIT != 0) {
for q = p; q != nil; q = q.Link {
if q.As == obj.ACALL {
goto noleaf
}
if (q.As == obj.ADUFFCOPY || q.As == obj.ADUFFZERO) && autoffset >= obj.StackSmall-8 {
goto noleaf
}
}
p.From3.Offset |= obj.NOSPLIT
noleaf:
}
q = 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, int32(textarg), bool2int(!(cursym.Text.From3.Offset&obj.NEEDCTXT != 0)), &q) // emit split check
}
if autoffset != 0 {
if autoffset%int32(ctxt.Arch.Regsize) != 0 {
ctxt.Diag("unaligned stack size %d", autoffset)
}
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 bpsize > 0 {
// Save caller's BP
p = obj.Appendp(ctxt, p)
p.As = AMOVQ
p.From.Type = obj.TYPE_REG
p.From.Reg = REG_BP
p.To.Type = obj.TYPE_MEM
p.To.Reg = REG_SP
p.To.Scale = 1
p.To.Offset = int64(autoffset) - int64(bpsize)
// Move current frame to BP
p = obj.Appendp(ctxt, p)
p.As = ALEAQ
p.From.Type = obj.TYPE_MEM
p.From.Reg = REG_SP
p.From.Scale = 1
p.From.Offset = int64(autoffset) - int64(bpsize)
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_BP
}
if cursym.Text.From3.Offset&obj.WRAPPER != 0 {
// if(g->panic != nil && g->panic->argp == FP) g->panic->argp = bottom-of-frame
//
// MOVQ g_panic(CX), BX
// TESTQ BX, BX
// JEQ end
// LEAQ (autoffset+8)(SP), DI
// CMPQ panic_argp(BX), DI
// JNE end
// MOVQ 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 = AMOVQ
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
if ctxt.Headtype == obj.Hnacl {
p.As = AMOVL
p.From.Type = obj.TYPE_MEM
p.From.Reg = REG_R15
p.From.Scale = 1
p.From.Index = REG_CX
}
p = obj.Appendp(ctxt, p)
p.As = ATESTQ
p.From.Type = obj.TYPE_REG
p.From.Reg = REG_BX
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_BX
if ctxt.Headtype == obj.Hnacl {
p.As = ATESTL
}
p = obj.Appendp(ctxt, p)
p.As = AJEQ
p.To.Type = obj.TYPE_BRANCH
p1 = p
p = obj.Appendp(ctxt, p)
p.As = ALEAQ
p.From.Type = obj.TYPE_MEM
p.From.Reg = REG_SP
p.From.Offset = int64(autoffset) + 8
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_DI
if ctxt.Headtype == obj.Hnacl {
p.As = ALEAL
}
p = obj.Appendp(ctxt, p)
p.As = ACMPQ
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
if ctxt.Headtype == obj.Hnacl {
p.As = ACMPL
p.From.Type = obj.TYPE_MEM
p.From.Reg = REG_R15
p.From.Scale = 1
p.From.Index = REG_BX
}
p = obj.Appendp(ctxt, p)
p.As = AJNE
p.To.Type = obj.TYPE_BRANCH
p2 = p
p = obj.Appendp(ctxt, p)
p.As = AMOVQ
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
if ctxt.Headtype == obj.Hnacl {
p.As = AMOVL
p.To.Type = obj.TYPE_MEM
p.To.Reg = REG_R15
p.To.Scale = 1
p.To.Index = REG_BX
}
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) {
// 6l -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 = AMOVQ
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 = AMOVQ
p.From.Type = obj.TYPE_CONST
p.From.Offset = int64(autoffset) / 8
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_CX
p = obj.Appendp(ctxt, p)
p.As = AMOVQ
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 = ASTOSQ
}
for ; p != nil; p = p.Link {
pcsize = int(p.Mode) / 8
a = int(p.From.Name)
if a == obj.NAME_AUTO {
p.From.Offset += int64(deltasp) - int64(bpsize)
}
if a == obj.NAME_PARAM {
p.From.Offset += int64(deltasp) + int64(pcsize)
}
a = int(p.To.Name)
if a == obj.NAME_AUTO {
p.To.Offset += int64(deltasp) - int64(bpsize)
}
if a == obj.NAME_PARAM {
p.To.Offset += int64(deltasp) + int64(pcsize)
}
switch p.As {
default:
continue
case APUSHL,
APUSHFL:
deltasp += 4
p.Spadj = 4
continue
case APUSHQ,
APUSHFQ:
deltasp += 8
p.Spadj = 8
continue
case APUSHW,
APUSHFW:
deltasp += 2
p.Spadj = 2
continue
case APOPL,
APOPFL:
deltasp -= 4
p.Spadj = -4
continue
case APOPQ,
APOPFQ:
deltasp -= 8
p.Spadj = -8
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 {
if bpsize > 0 {
// Restore caller's BP
p.As = AMOVQ
p.From.Type = obj.TYPE_MEM
p.From.Reg = REG_SP
p.From.Scale = 1
p.From.Offset = int64(autoffset) - int64(bpsize)
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_BP
p = obj.Appendp(ctxt, p)
}
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
}
}
}
func indir_cx(ctxt *obj.Link, a *obj.Addr) {
if ctxt.Headtype == obj.Hnacl {
a.Type = obj.TYPE_MEM
a.Reg = REG_R15
a.Index = REG_CX
a.Scale = 1
return
}
a.Type = obj.TYPE_MEM
a.Reg = REG_CX
}
// 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 {
var next *obj.Prog
p.As = AMOVQ
if ctxt.Arch.Ptrsize == 4 {
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, textarg int32, noctxt int, jmpok **obj.Prog) *obj.Prog {
var q *obj.Prog
var q1 *obj.Prog
var cmp int
var lea int
var mov int
var sub int
cmp = ACMPQ
lea = ALEAQ
mov = AMOVQ
sub = ASUBQ
if ctxt.Headtype == obj.Hnacl {
cmp = ACMPL
lea = ALEAL
mov = AMOVL
sub = ASUBL
}
q1 = nil
if framesize <= obj.StackSmall {
// small stack: SP <= stackguard
// CMPQ SP, stackguard
p = obj.Appendp(ctxt, p)
p.As = int16(cmp)
p.From.Type = obj.TYPE_REG
p.From.Reg = REG_SP
indir_cx(ctxt, &p.To)
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
// LEAQ -xxx(SP), AX
// CMPQ AX, stackguard
p = obj.Appendp(ctxt, p)
p.As = int16(lea)
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 = int16(cmp)
p.From.Type = obj.TYPE_REG
p.From.Reg = REG_AX
indir_cx(ctxt, &p.To)
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.
// MOVQ stackguard, CX
// CMPQ CX, $StackPreempt
// JEQ label-of-call-to-morestack
// LEAQ StackGuard(SP), AX
// SUBQ CX, AX
// CMPQ AX, $(framesize+(StackGuard-StackSmall))
p = obj.Appendp(ctxt, p)
p.As = int16(mov)
indir_cx(ctxt, &p.From)
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 = int16(cmp)
p.From.Type = obj.TYPE_REG
p.From.Reg = REG_SI
p.To.Type = obj.TYPE_CONST
p.To.Offset = obj.StackPreempt
p = obj.Appendp(ctxt, p)
p.As = AJEQ
p.To.Type = obj.TYPE_BRANCH
q1 = p
p = obj.Appendp(ctxt, p)
p.As = int16(lea)
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 = int16(sub)
p.From.Type = obj.TYPE_REG
p.From.Reg = REG_SI
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_AX
p = obj.Appendp(ctxt, p)
p.As = int16(cmp)
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
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[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) {
var firstp *obj.Prog
var lastp *obj.Prog
ctxt.Cursym = s
firstp = new(obj.Prog)
lastp = firstp
xfol(ctxt, s.Text, &lastp)
lastp.Link = nil
s.Text = firstp.Link
}
func nofollow(a int) int {
switch a {
case obj.AJMP,
obj.ARET,
AIRETL,
AIRETQ,
AIRETW,
ARETFL,
ARETFQ,
ARETFW,
obj.AUNDEF:
return 1
}
return 0
}
func pushpop(a int) int {
switch a {
case APUSHL,
APUSHFL,
APUSHQ,
APUSHFQ,
APUSHW,
APUSHFW,
APOPL,
APOPFL,
APOPQ,
APOPFQ,
APOPW,
APOPFW:
return 1
}
return 0
}
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) != 0 || pushpop(a) != 0 {
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 = new(obj.Prog)
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) != 0 {
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 Linkamd64 = obj.LinkArch{
ByteOrder: binary.LittleEndian,
Pconv: Pconv,
Name: "amd64",
Thechar: '6',
Endian: obj.LittleEndian,
Preprocess: preprocess,
Assemble: span6,
Follow: follow,
Progedit: progedit,
Minlc: 1,
Ptrsize: 8,
Regsize: 8,
}
var Linkamd64p32 = obj.LinkArch{
ByteOrder: binary.LittleEndian,
Pconv: Pconv,
Name: "amd64p32",
Thechar: '6',
Endian: obj.LittleEndian,
Preprocess: preprocess,
Assemble: span6,
Follow: follow,
Progedit: progedit,
Minlc: 1,
Ptrsize: 4,
Regsize: 8,
}
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