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838 lines (736 loc) · 21.4 KB
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// Derived from Inferno utils/5c/swt.c
// https://bitbucket.org/inferno-os/inferno-os/src/master/utils/5c/swt.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 arm
import (
"cmd/internal/obj"
"cmd/internal/objabi"
"cmd/internal/sys"
"internal/buildcfg"
"log"
)
var progedit_tlsfallback *obj.LSym
func progedit(ctxt *obj.Link, p *obj.Prog, newprog obj.ProgAlloc) {
p.From.Class = 0
p.To.Class = 0
c := ctxt5{ctxt: ctxt, newprog: newprog}
// Rewrite B/BL to symbol as TYPE_BRANCH.
switch p.As {
case AB, ABL, obj.ADUFFZERO, obj.ADUFFCOPY:
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
}
}
// Replace TLS register fetches on older ARM processors.
switch p.As {
// Treat MRC 15, 0, <reg>, C13, C0, 3 specially.
case AMRC:
if p.To.Offset&0xffff0fff == 0xee1d0f70 {
// Because the instruction might be rewritten to a BL which returns in R0
// the register must be zero.
if p.To.Offset&0xf000 != 0 {
ctxt.Diag("%v: TLS MRC instruction must write to R0 as it might get translated into a BL instruction", p.Line())
}
if buildcfg.GOARM < 7 {
// Replace it with BL runtime.read_tls_fallback(SB) for ARM CPUs that lack the tls extension.
if progedit_tlsfallback == nil {
progedit_tlsfallback = ctxt.Lookup("runtime.read_tls_fallback")
}
// MOVW LR, R11
p.As = AMOVW
p.From.Type = obj.TYPE_REG
p.From.Reg = REGLINK
p.To.Type = obj.TYPE_REG
p.To.Reg = REGTMP
// BL runtime.read_tls_fallback(SB)
p = obj.Appendp(p, newprog)
p.As = ABL
p.To.Type = obj.TYPE_BRANCH
p.To.Sym = progedit_tlsfallback
p.To.Offset = 0
// MOVW R11, LR
p = obj.Appendp(p, newprog)
p.As = AMOVW
p.From.Type = obj.TYPE_REG
p.From.Reg = REGTMP
p.To.Type = obj.TYPE_REG
p.To.Reg = REGLINK
break
}
}
// Otherwise, MRC/MCR instructions need no further treatment.
p.As = AWORD
}
// Rewrite float constants to values stored in memory.
switch p.As {
case AMOVF:
if p.From.Type == obj.TYPE_FCONST && c.chipfloat5(p.From.Val.(float64)) < 0 && (c.chipzero5(p.From.Val.(float64)) < 0 || p.Scond&C_SCOND != C_SCOND_NONE) {
f32 := float32(p.From.Val.(float64))
p.From.Type = obj.TYPE_MEM
p.From.Sym = ctxt.Float32Sym(f32)
p.From.Name = obj.NAME_EXTERN
p.From.Offset = 0
}
case AMOVD:
if p.From.Type == obj.TYPE_FCONST && c.chipfloat5(p.From.Val.(float64)) < 0 && (c.chipzero5(p.From.Val.(float64)) < 0 || p.Scond&C_SCOND != C_SCOND_NONE) {
p.From.Type = obj.TYPE_MEM
p.From.Sym = ctxt.Float64Sym(p.From.Val.(float64))
p.From.Name = obj.NAME_EXTERN
p.From.Offset = 0
}
}
if ctxt.Flag_dynlink {
c.rewriteToUseGot(p)
}
}
// Rewrite p, if necessary, to access global data via the global offset table.
func (c *ctxt5) rewriteToUseGot(p *obj.Prog) {
if p.As == obj.ADUFFCOPY || p.As == obj.ADUFFZERO {
// ADUFFxxx $offset
// becomes
// MOVW runtime.duffxxx@GOT, R9
// ADD $offset, R9
// CALL (R9)
var sym *obj.LSym
if p.As == obj.ADUFFZERO {
sym = c.ctxt.Lookup("runtime.duffzero")
} else {
sym = c.ctxt.Lookup("runtime.duffcopy")
}
offset := p.To.Offset
p.As = AMOVW
p.From.Type = obj.TYPE_MEM
p.From.Name = obj.NAME_GOTREF
p.From.Sym = sym
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_R9
p.To.Name = obj.NAME_NONE
p.To.Offset = 0
p.To.Sym = nil
p1 := obj.Appendp(p, c.newprog)
p1.As = AADD
p1.From.Type = obj.TYPE_CONST
p1.From.Offset = offset
p1.To.Type = obj.TYPE_REG
p1.To.Reg = REG_R9
p2 := obj.Appendp(p1, c.newprog)
p2.As = obj.ACALL
p2.To.Type = obj.TYPE_MEM
p2.To.Reg = REG_R9
return
}
// We only care about global data: NAME_EXTERN means a global
// symbol in the Go sense, and p.Sym.Local is true for a few
// internally defined symbols.
if p.From.Type == obj.TYPE_ADDR && p.From.Name == obj.NAME_EXTERN && !p.From.Sym.Local() {
// MOVW $sym, Rx becomes MOVW sym@GOT, Rx
// MOVW $sym+<off>, Rx becomes MOVW sym@GOT, Rx; ADD <off>, Rx
if p.As != AMOVW {
c.ctxt.Diag("do not know how to handle TYPE_ADDR in %v with -dynlink", p)
}
if p.To.Type != obj.TYPE_REG {
c.ctxt.Diag("do not know how to handle LEAQ-type insn to non-register in %v with -dynlink", p)
}
p.From.Type = obj.TYPE_MEM
p.From.Name = obj.NAME_GOTREF
if p.From.Offset != 0 {
q := obj.Appendp(p, c.newprog)
q.As = AADD
q.From.Type = obj.TYPE_CONST
q.From.Offset = p.From.Offset
q.To = p.To
p.From.Offset = 0
}
}
if p.GetFrom3() != nil && p.GetFrom3().Name == obj.NAME_EXTERN {
c.ctxt.Diag("don't know how to handle %v with -dynlink", p)
}
var source *obj.Addr
// MOVx sym, Ry becomes MOVW sym@GOT, R9; MOVx (R9), Ry
// MOVx Ry, sym becomes MOVW sym@GOT, R9; MOVx Ry, (R9)
// An addition may be inserted between the two MOVs if there is an offset.
if p.From.Name == obj.NAME_EXTERN && !p.From.Sym.Local() {
if p.To.Name == obj.NAME_EXTERN && !p.To.Sym.Local() {
c.ctxt.Diag("cannot handle NAME_EXTERN on both sides in %v with -dynlink", p)
}
source = &p.From
} else if p.To.Name == obj.NAME_EXTERN && !p.To.Sym.Local() {
source = &p.To
} else {
return
}
if p.As == obj.ATEXT || p.As == obj.AFUNCDATA || p.As == obj.ACALL || p.As == obj.ARET || p.As == obj.AJMP {
return
}
if source.Sym.Type == objabi.STLSBSS {
return
}
if source.Type != obj.TYPE_MEM {
c.ctxt.Diag("don't know how to handle %v with -dynlink", p)
}
p1 := obj.Appendp(p, c.newprog)
p2 := obj.Appendp(p1, c.newprog)
p1.As = AMOVW
p1.From.Type = obj.TYPE_MEM
p1.From.Sym = source.Sym
p1.From.Name = obj.NAME_GOTREF
p1.To.Type = obj.TYPE_REG
p1.To.Reg = REG_R9
p2.As = p.As
p2.From = p.From
p2.To = p.To
if p.From.Name == obj.NAME_EXTERN {
p2.From.Reg = REG_R9
p2.From.Name = obj.NAME_NONE
p2.From.Sym = nil
} else if p.To.Name == obj.NAME_EXTERN {
p2.To.Reg = REG_R9
p2.To.Name = obj.NAME_NONE
p2.To.Sym = nil
} else {
return
}
obj.Nopout(p)
}
// Prog.mark
const (
FOLL = 1 << 0
LABEL = 1 << 1
LEAF = 1 << 2
)
func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
autosize := int32(0)
if cursym.Func().Text == nil || cursym.Func().Text.Link == nil {
return
}
c := ctxt5{ctxt: ctxt, cursym: cursym, newprog: newprog}
p := c.cursym.Func().Text
autoffset := int32(p.To.Offset)
if autoffset == -4 {
// Historical way to mark NOFRAME.
p.From.Sym.Set(obj.AttrNoFrame, true)
autoffset = 0
}
if autoffset < 0 || autoffset%4 != 0 {
c.ctxt.Diag("frame size %d not 0 or a positive multiple of 4", autoffset)
}
if p.From.Sym.NoFrame() {
if autoffset != 0 {
c.ctxt.Diag("NOFRAME functions must have a frame size of 0, not %d", autoffset)
}
}
cursym.Func().Locals = autoffset
cursym.Func().Args = p.To.Val.(int32)
/*
* find leaf subroutines
*/
for p := cursym.Func().Text; p != nil; p = p.Link {
switch p.As {
case obj.ATEXT:
p.Mark |= LEAF
case ADIV, ADIVU, AMOD, AMODU:
cursym.Func().Text.Mark &^= LEAF
case ABL,
ABX,
obj.ADUFFZERO,
obj.ADUFFCOPY:
cursym.Func().Text.Mark &^= LEAF
}
}
var q2 *obj.Prog
for p := cursym.Func().Text; p != nil; p = p.Link {
o := p.As
switch o {
case obj.ATEXT:
autosize = autoffset
if p.Mark&LEAF != 0 && autosize == 0 {
// A leaf function with no locals has no frame.
p.From.Sym.Set(obj.AttrNoFrame, true)
}
if !p.From.Sym.NoFrame() {
// If there is a stack frame at all, it includes
// space to save the LR.
autosize += 4
}
if autosize == 0 && cursym.Func().Text.Mark&LEAF == 0 {
// A very few functions that do not return to their caller
// are not identified as leaves but still have no frame.
if ctxt.Debugvlog {
ctxt.Logf("save suppressed in: %s\n", cursym.Name)
}
cursym.Func().Text.Mark |= LEAF
}
// FP offsets need an updated p.To.Offset.
p.To.Offset = int64(autosize) - 4
if cursym.Func().Text.Mark&LEAF != 0 {
cursym.Set(obj.AttrLeaf, true)
if p.From.Sym.NoFrame() {
break
}
}
if !p.From.Sym.NoSplit() {
p = c.stacksplit(p, autosize) // emit split check
}
// MOVW.W R14,$-autosize(SP)
p = obj.Appendp(p, c.newprog)
p.As = AMOVW
p.Scond |= C_WBIT
p.From.Type = obj.TYPE_REG
p.From.Reg = REGLINK
p.To.Type = obj.TYPE_MEM
p.To.Offset = int64(-autosize)
p.To.Reg = REGSP
p.Spadj = autosize
if cursym.Func().Text.From.Sym.Wrapper() {
// if(g->panic != nil && g->panic->argp == FP) g->panic->argp = bottom-of-frame
//
// MOVW g_panic(g), R1
// CMP $0, R1
// B.NE checkargp
// end:
// NOP
// ... function ...
// checkargp:
// MOVW panic_argp(R1), R2
// ADD $(autosize+4), R13, R3
// CMP R2, R3
// B.NE end
// ADD $4, R13, R4
// MOVW R4, panic_argp(R1)
// B end
//
// The NOP is needed to give the jumps somewhere to land.
// It is a liblink NOP, not an ARM NOP: it encodes to 0 instruction bytes.
p = obj.Appendp(p, newprog)
p.As = AMOVW
p.From.Type = obj.TYPE_MEM
p.From.Reg = REGG
p.From.Offset = 4 * int64(ctxt.Arch.PtrSize) // G.panic
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_R1
p = obj.Appendp(p, newprog)
p.As = ACMP
p.From.Type = obj.TYPE_CONST
p.From.Offset = 0
p.Reg = REG_R1
// B.NE checkargp
bne := obj.Appendp(p, newprog)
bne.As = ABNE
bne.To.Type = obj.TYPE_BRANCH
// end: NOP
end := obj.Appendp(bne, newprog)
end.As = obj.ANOP
// find end of function
var last *obj.Prog
for last = end; last.Link != nil; last = last.Link {
}
// MOVW panic_argp(R1), R2
mov := obj.Appendp(last, newprog)
mov.As = AMOVW
mov.From.Type = obj.TYPE_MEM
mov.From.Reg = REG_R1
mov.From.Offset = 0 // Panic.argp
mov.To.Type = obj.TYPE_REG
mov.To.Reg = REG_R2
// B.NE branch target is MOVW above
bne.To.SetTarget(mov)
// ADD $(autosize+4), R13, R3
p = obj.Appendp(mov, newprog)
p.As = AADD
p.From.Type = obj.TYPE_CONST
p.From.Offset = int64(autosize) + 4
p.Reg = REG_R13
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_R3
// CMP R2, R3
p = obj.Appendp(p, newprog)
p.As = ACMP
p.From.Type = obj.TYPE_REG
p.From.Reg = REG_R2
p.Reg = REG_R3
// B.NE end
p = obj.Appendp(p, newprog)
p.As = ABNE
p.To.Type = obj.TYPE_BRANCH
p.To.SetTarget(end)
// ADD $4, R13, R4
p = obj.Appendp(p, newprog)
p.As = AADD
p.From.Type = obj.TYPE_CONST
p.From.Offset = 4
p.Reg = REG_R13
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_R4
// MOVW R4, panic_argp(R1)
p = obj.Appendp(p, newprog)
p.As = AMOVW
p.From.Type = obj.TYPE_REG
p.From.Reg = REG_R4
p.To.Type = obj.TYPE_MEM
p.To.Reg = REG_R1
p.To.Offset = 0 // Panic.argp
// B end
p = obj.Appendp(p, newprog)
p.As = AB
p.To.Type = obj.TYPE_BRANCH
p.To.SetTarget(end)
// reset for subsequent passes
p = end
}
case obj.ARET:
nocache(p)
if cursym.Func().Text.Mark&LEAF != 0 {
if autosize == 0 {
p.As = AB
p.From = obj.Addr{}
if p.To.Sym != nil { // retjmp
p.To.Type = obj.TYPE_BRANCH
} else {
p.To.Type = obj.TYPE_MEM
p.To.Offset = 0
p.To.Reg = REGLINK
}
break
}
}
p.As = AMOVW
p.Scond |= C_PBIT
p.From.Type = obj.TYPE_MEM
p.From.Offset = int64(autosize)
p.From.Reg = REGSP
p.To.Type = obj.TYPE_REG
p.To.Reg = REGPC
// If there are instructions following
// this ARET, they come from a branch
// with the same stackframe, so no spadj.
if p.To.Sym != nil { // retjmp
p.To.Reg = REGLINK
q2 = obj.Appendp(p, newprog)
q2.As = AB
q2.To.Type = obj.TYPE_BRANCH
q2.To.Sym = p.To.Sym
p.To.Sym = nil
p.To.Name = obj.NAME_NONE
p = q2
}
case AADD:
if p.From.Type == obj.TYPE_CONST && p.From.Reg == 0 && p.To.Type == obj.TYPE_REG && p.To.Reg == REGSP {
p.Spadj = int32(-p.From.Offset)
}
case ASUB:
if p.From.Type == obj.TYPE_CONST && p.From.Reg == 0 && p.To.Type == obj.TYPE_REG && p.To.Reg == REGSP {
p.Spadj = int32(p.From.Offset)
}
case ADIV, ADIVU, AMOD, AMODU:
if cursym.Func().Text.From.Sym.NoSplit() {
ctxt.Diag("cannot divide in NOSPLIT function")
}
const debugdivmod = false
if debugdivmod {
break
}
if p.From.Type != obj.TYPE_REG {
break
}
if p.To.Type != obj.TYPE_REG {
break
}
// Make copy because we overwrite p below.
q1 := *p
if q1.Reg == REGTMP || q1.Reg == 0 && q1.To.Reg == REGTMP {
ctxt.Diag("div already using REGTMP: %v", p)
}
/* MOV m(g),REGTMP */
p.As = AMOVW
p.Pos = q1.Pos
p.From.Type = obj.TYPE_MEM
p.From.Reg = REGG
p.From.Offset = 6 * 4 // offset of g.m
p.Reg = 0
p.To.Type = obj.TYPE_REG
p.To.Reg = REGTMP
/* MOV a,m_divmod(REGTMP) */
p = obj.Appendp(p, newprog)
p.As = AMOVW
p.Pos = q1.Pos
p.From.Type = obj.TYPE_REG
p.From.Reg = q1.From.Reg
p.To.Type = obj.TYPE_MEM
p.To.Reg = REGTMP
p.To.Offset = 8 * 4 // offset of m.divmod
/* MOV b, R8 */
p = obj.Appendp(p, newprog)
p.As = AMOVW
p.Pos = q1.Pos
p.From.Type = obj.TYPE_REG
p.From.Reg = q1.Reg
if q1.Reg == 0 {
p.From.Reg = q1.To.Reg
}
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_R8
p.To.Offset = 0
/* CALL appropriate */
p = obj.Appendp(p, newprog)
p.As = ABL
p.Pos = q1.Pos
p.To.Type = obj.TYPE_BRANCH
switch o {
case ADIV:
p.To.Sym = symdiv
case ADIVU:
p.To.Sym = symdivu
case AMOD:
p.To.Sym = symmod
case AMODU:
p.To.Sym = symmodu
}
/* MOV REGTMP, b */
p = obj.Appendp(p, newprog)
p.As = AMOVW
p.Pos = q1.Pos
p.From.Type = obj.TYPE_REG
p.From.Reg = REGTMP
p.From.Offset = 0
p.To.Type = obj.TYPE_REG
p.To.Reg = q1.To.Reg
case AMOVW:
if (p.Scond&C_WBIT != 0) && p.To.Type == obj.TYPE_MEM && p.To.Reg == REGSP {
p.Spadj = int32(-p.To.Offset)
}
if (p.Scond&C_PBIT != 0) && p.From.Type == obj.TYPE_MEM && p.From.Reg == REGSP && p.To.Reg != REGPC {
p.Spadj = int32(-p.From.Offset)
}
if p.From.Type == obj.TYPE_ADDR && p.From.Reg == REGSP && p.To.Type == obj.TYPE_REG && p.To.Reg == REGSP {
p.Spadj = int32(-p.From.Offset)
}
case obj.AGETCALLERPC:
if cursym.Leaf() {
/* MOVW LR, Rd */
p.As = AMOVW
p.From.Type = obj.TYPE_REG
p.From.Reg = REGLINK
} else {
/* MOVW (RSP), Rd */
p.As = AMOVW
p.From.Type = obj.TYPE_MEM
p.From.Reg = REGSP
}
}
if p.To.Type == obj.TYPE_REG && p.To.Reg == REGSP && p.Spadj == 0 {
f := c.cursym.Func()
if f.FuncFlag&objabi.FuncFlag_SPWRITE == 0 {
c.cursym.Func().FuncFlag |= objabi.FuncFlag_SPWRITE
if ctxt.Debugvlog || !ctxt.IsAsm {
ctxt.Logf("auto-SPWRITE: %s %v\n", c.cursym.Name, p)
if !ctxt.IsAsm {
ctxt.Diag("invalid auto-SPWRITE in non-assembly")
ctxt.DiagFlush()
log.Fatalf("bad SPWRITE")
}
}
}
}
}
}
func (c *ctxt5) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
if c.ctxt.Flag_maymorestack != "" {
// Save LR and make room for REGCTXT.
const frameSize = 8
// MOVW.W R14,$-8(SP)
p = obj.Appendp(p, c.newprog)
p.As = AMOVW
p.Scond |= C_WBIT
p.From.Type = obj.TYPE_REG
p.From.Reg = REGLINK
p.To.Type = obj.TYPE_MEM
p.To.Offset = -frameSize
p.To.Reg = REGSP
p.Spadj = frameSize
// MOVW REGCTXT, 4(SP)
p = obj.Appendp(p, c.newprog)
p.As = AMOVW
p.From.Type = obj.TYPE_REG
p.From.Reg = REGCTXT
p.To.Type = obj.TYPE_MEM
p.To.Offset = 4
p.To.Reg = REGSP
// CALL maymorestack
p = obj.Appendp(p, c.newprog)
p.As = obj.ACALL
p.To.Type = obj.TYPE_BRANCH
// See ../x86/obj6.go
p.To.Sym = c.ctxt.LookupABI(c.ctxt.Flag_maymorestack, c.cursym.ABI())
// Restore REGCTXT and LR.
// MOVW 4(SP), REGCTXT
p = obj.Appendp(p, c.newprog)
p.As = AMOVW
p.From.Type = obj.TYPE_MEM
p.From.Offset = 4
p.From.Reg = REGSP
p.To.Type = obj.TYPE_REG
p.To.Reg = REGCTXT
// MOVW.P 8(SP), R14
p.As = AMOVW
p.Scond |= C_PBIT
p.From.Type = obj.TYPE_MEM
p.From.Offset = frameSize
p.From.Reg = REGSP
p.To.Type = obj.TYPE_REG
p.To.Reg = REGLINK
p.Spadj = -frameSize
}
// Jump back to here after morestack returns.
startPred := p
// MOVW g_stackguard(g), R1
p = obj.Appendp(p, c.newprog)
p.As = AMOVW
p.From.Type = obj.TYPE_MEM
p.From.Reg = REGG
p.From.Offset = 2 * int64(c.ctxt.Arch.PtrSize) // G.stackguard0
if c.cursym.CFunc() {
p.From.Offset = 3 * int64(c.ctxt.Arch.PtrSize) // G.stackguard1
}
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_R1
// Mark the stack bound check and morestack call async nonpreemptible.
// If we get preempted here, when resumed the preemption request is
// cleared, but we'll still call morestack, which will double the stack
// unnecessarily. See issue #35470.
p = c.ctxt.StartUnsafePoint(p, c.newprog)
if framesize <= objabi.StackSmall {
// small stack: SP < stackguard
// CMP stackguard, SP
p = obj.Appendp(p, c.newprog)
p.As = ACMP
p.From.Type = obj.TYPE_REG
p.From.Reg = REG_R1
p.Reg = REGSP
} else if framesize <= objabi.StackBig {
// large stack: SP-framesize < stackguard-StackSmall
// MOVW $-(framesize-StackSmall)(SP), R2
// CMP stackguard, R2
p = obj.Appendp(p, c.newprog)
p.As = AMOVW
p.From.Type = obj.TYPE_ADDR
p.From.Reg = REGSP
p.From.Offset = -(int64(framesize) - objabi.StackSmall)
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_R2
p = obj.Appendp(p, c.newprog)
p.As = ACMP
p.From.Type = obj.TYPE_REG
p.From.Reg = REG_R1
p.Reg = REG_R2
} else {
// Such a large stack we need to protect against underflow.
// The runtime guarantees SP > objabi.StackBig, but
// framesize is large enough that SP-framesize may
// underflow, causing a direct comparison with the
// stack guard to incorrectly succeed. We explicitly
// guard against underflow.
//
// // Try subtracting from SP and check for underflow.
// // If this underflows, it sets C to 0.
// SUB.S $(framesize-StackSmall), SP, R2
// // If C is 1 (unsigned >=), compare with guard.
// CMP.HS stackguard, R2
p = obj.Appendp(p, c.newprog)
p.As = ASUB
p.Scond = C_SBIT
p.From.Type = obj.TYPE_CONST
p.From.Offset = int64(framesize) - objabi.StackSmall
p.Reg = REGSP
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_R2
p = obj.Appendp(p, c.newprog)
p.As = ACMP
p.Scond = C_SCOND_HS
p.From.Type = obj.TYPE_REG
p.From.Reg = REG_R1
p.Reg = REG_R2
}
// BLS call-to-morestack (C is 0 or Z is 1)
bls := obj.Appendp(p, c.newprog)
bls.As = ABLS
bls.To.Type = obj.TYPE_BRANCH
end := c.ctxt.EndUnsafePoint(bls, c.newprog, -1)
var last *obj.Prog
for last = c.cursym.Func().Text; last.Link != nil; last = last.Link {
}
// Now we are at the end of the function, but logically
// we are still in function prologue. We need to fix the
// SP data and PCDATA.
spfix := obj.Appendp(last, c.newprog)
spfix.As = obj.ANOP
spfix.Spadj = -framesize
pcdata := c.ctxt.EmitEntryStackMap(c.cursym, spfix, c.newprog)
pcdata = c.ctxt.StartUnsafePoint(pcdata, c.newprog)
// MOVW LR, R3
movw := obj.Appendp(pcdata, c.newprog)
movw.As = AMOVW
movw.From.Type = obj.TYPE_REG
movw.From.Reg = REGLINK
movw.To.Type = obj.TYPE_REG
movw.To.Reg = REG_R3
bls.To.SetTarget(movw)
// BL runtime.morestack
call := obj.Appendp(movw, c.newprog)
call.As = obj.ACALL
call.To.Type = obj.TYPE_BRANCH
morestack := "runtime.morestack"
switch {
case c.cursym.CFunc():
morestack = "runtime.morestackc"
case !c.cursym.Func().Text.From.Sym.NeedCtxt():
morestack = "runtime.morestack_noctxt"
}
call.To.Sym = c.ctxt.Lookup(morestack)
pcdata = c.ctxt.EndUnsafePoint(call, c.newprog, -1)
// B start
b := obj.Appendp(pcdata, c.newprog)
b.As = obj.AJMP
b.To.Type = obj.TYPE_BRANCH
b.To.SetTarget(startPred.Link)
b.Spadj = +framesize
return end
}
var unaryDst = map[obj.As]bool{
ASWI: true,
AWORD: true,
}
var Linkarm = obj.LinkArch{
Arch: sys.ArchARM,
Init: buildop,
Preprocess: preprocess,
Assemble: span5,
Progedit: progedit,
UnaryDst: unaryDst,
DWARFRegisters: ARMDWARFRegisters,
}