golang ggen 代码
文件路径：/src/cmd/compile/internal/amd64/ggen.go
/ Copyright 2009 The Go Authors. All rights reserved.
/ Use of this source code is governed by a BSD-style
/ license that can be found in the LICENSE file.
package amd64
import (
"cmd/compile/internal/base"
"cmd/compile/internal/ir"
"cmd/compile/internal/objw"
"cmd/compile/internal/types"
"cmd/internal/obj"
"cmd/internal/obj/x86"
"internal/buildcfg"
)
/ no floating point in note handlers on Plan 9
var isPlan9 = buildcfg.GOOS == "plan9"
/ DUFFZERO consists of repeated blocks of 4 MOVUPSs + LEAQ,
/ See runtime/mkduff.go.
const (
dzBlocks = 16 / number of MOV/ADD blocks
dzBlockLen = 4 / number of clears per block
dzBlockSize = 23 / size of instructions in a single block
dzMovSize = 5 / size of single MOV instruction w/ offset
dzLeaqSize = 4 / size of single LEAQ instruction
dzClearStep = 16 / number of bytes cleared by each MOV instruction
dzClearLen = dzClearStep * dzBlockLen / bytes cleared by one block
dzSize = dzBlocks * dzBlockSize
)
/ dzOff returns the offset for a jump into DUFFZERO.
/ b is the number of bytes to zero.
func dzOff(b int64) int64 {
off := int64(dzSize)
off -= b / dzClearLen * dzBlockSize
tailLen := b % dzClearLen
if tailLen >= dzClearStep {
off -= dzLeaqSize + dzMovSize*(tailLen/dzClearStep)
}
return off
}
/ duffzeroDI returns the pre-adjustment to DI for a call to DUFFZERO.
/ b is the number of bytes to zero.
func dzDI(b int64) int64 {
tailLen := b % dzClearLen
if tailLen < dzClearStep {
return 0
}
tailSteps := tailLen / dzClearStep
return -dzClearStep * (dzBlockLen - tailSteps)
}
func zerorange(pp *objw.Progs, p *obj.Prog, off, cnt int64, state *uint32) *obj.Prog {
const (
r13 = 1 << iota / if R13 is already zeroed.
)
if cnt == 0 {
return p
}
if cnt%int64(types.RegSize) != 0 {
/ should only happen with nacl
if cnt%int64(types.PtrSize) != 0 {
base.Fatalf("zerorange count not a multiple of widthptr %d", cnt)
}
if *state&r13 == 0 {
p = pp.Append(p, x86.AMOVQ, obj.TYPE_CONST, 0, 0, obj.TYPE_REG, x86.REG_R13, 0)
*state |= r13
}
p = pp.Append(p, x86.AMOVL, obj.TYPE_REG, x86.REG_R13, 0, obj.TYPE_MEM, x86.REG_SP, off)
off += int64(types.PtrSize)
cnt -= int64(types.PtrSize)
}
if cnt == 8 {
if *state&r13 == 0 {
p = pp.Append(p, x86.AMOVQ, obj.TYPE_CONST, 0, 0, obj.TYPE_REG, x86.REG_R13, 0)
*state |= r13
}
p = pp.Append(p, x86.AMOVQ, obj.TYPE_REG, x86.REG_R13, 0, obj.TYPE_MEM, x86.REG_SP, off)
} else if !isPlan9 && cnt <= int64(8*types.RegSize) {
for i := int64(0); i < cnt/16; i++ {
p = pp.Append(p, x86.AMOVUPS, obj.TYPE_REG, x86.REG_X15, 0, obj.TYPE_MEM, x86.REG_SP, off+i*16)
}
if cnt%16 != 0 {
p = pp.Append(p, x86.AMOVUPS, obj.TYPE_REG, x86.REG_X15, 0, obj.TYPE_MEM, x86.REG_SP, off+cnt-int64(16))
}
} else if !isPlan9 && (cnt <= int64(128*types.RegSize)) {
/ Save DI to r12. With the amd64 Go register abi, DI can contain
/ an incoming parameter, whereas R12 is always scratch.
p = pp.Append(p, x86.AMOVQ, obj.TYPE_REG, x86.REG_DI, 0, obj.TYPE_REG, x86.REG_R12, 0)
/ Emit duffzero call
p = pp.Append(p, leaptr, obj.TYPE_MEM, x86.REG_SP, off+dzDI(cnt), obj.TYPE_REG, x86.REG_DI, 0)
p = pp.Append(p, obj.ADUFFZERO, obj.TYPE_NONE, 0, 0, obj.TYPE_ADDR, 0, dzOff(cnt))
p.To.Sym = ir.Syms.Duffzero
if cnt%16 != 0 {
p = pp.Append(p, x86.AMOVUPS, obj.TYPE_REG, x86.REG_X15, 0, obj.TYPE_MEM, x86.REG_DI, -int64(8))
}
/ Restore DI from r12
p = pp.Append(p, x86.AMOVQ, obj.TYPE_REG, x86.REG_R12, 0, obj.TYPE_REG, x86.REG_DI, 0)
} else {
/ When the register ABI is in effect, at this point in the
/ prolog we may have live values in all of RAX,RDI,RCX. Save
/ them off to registers before the REPSTOSQ below, then
/ restore. Note that R12 and R13 are always available as
/ scratch regs; here we also use R15 (this is safe to do
/ since there won't be any globals accessed in the prolog).
/ See rewriteToUseGot() in obj6.go for more on r15 use.
/ Save rax/rdi/rcx
p = pp.Append(p, x86.AMOVQ, obj.TYPE_REG, x86.REG_DI, 0, obj.TYPE_REG, x86.REG_R12, 0)
p = pp.Append(p, x86.AMOVQ, obj.TYPE_REG, x86.REG_AX, 0, obj.TYPE_REG, x86.REG_R13, 0)
p = pp.Append(p, x86.AMOVQ, obj.TYPE_REG, x86.REG_CX, 0, obj.TYPE_REG, x86.REG_R15, 0)
/ Set up the REPSTOSQ and kick it off.
p = pp.Append(p, x86.AMOVQ, obj.TYPE_CONST, 0, 0, obj.TYPE_REG, x86.REG_AX, 0)
p = pp.Append(p, x86.AMOVQ, obj.TYPE_CONST, 0, cnt/int64(types.RegSize), obj.TYPE_REG, x86.REG_CX, 0)
p = pp.Append(p, leaptr, obj.TYPE_MEM, x86.REG_SP, off, obj.TYPE_REG, x86.REG_DI, 0)
p = pp.Append(p, x86.AREP, obj.TYPE_NONE, 0, 0, obj.TYPE_NONE, 0, 0)
p = pp.Append(p, x86.ASTOSQ, obj.TYPE_NONE, 0, 0, obj.TYPE_NONE, 0, 0)
/ Restore rax/rdi/rcx
p = pp.Append(p, x86.AMOVQ, obj.TYPE_REG, x86.REG_R12, 0, obj.TYPE_REG, x86.REG_DI, 0)
p = pp.Append(p, x86.AMOVQ, obj.TYPE_REG, x86.REG_R13, 0, obj.TYPE_REG, x86.REG_AX, 0)
p = pp.Append(p, x86.AMOVQ, obj.TYPE_REG, x86.REG_R15, 0, obj.TYPE_REG, x86.REG_CX, 0)
/ Record the fact that r13 is no longer zero.
*state &= ^uint32(r13)
}
return p
}
func ginsnop(pp *objw.Progs) *obj.Prog {
/ This is a hardware nop (1-byte 0x90) instruction,
/ even though we describe it as an explicit XCHGL here.
/ Particularly, this does not zero the high 32 bits
/ like typical *L opcodes.
/ (gas assembles "xchg %eax,%eax" to 0x87 0xc0, which
/ does zero the high 32 bits.)
p := pp.Prog(x86.AXCHGL)
p.From.Type = obj.TYPE_REG
p.From.Reg = x86.REG_AX
p.To.Type = obj.TYPE_REG
p.To.Reg = x86.REG_AX
return p
}