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cmd/internal/obj/x86: add named consts for Prog.Back flags

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Passes toolstash-check.

Change-Id: I7232ba43895a54b03cc328bb2e99c05c44eb6e8e
Reviewed-on: https://go-review.googlesource.com/107057
Reviewed-by: Ilya Tocar <ilya.tocar@intel.com>
Run-TryBot: Iskander Sharipov <iskander.sharipov@intel.com>
This commit is contained in:
quasilyte 2018-04-14 11:07:52 +03:00 committed by Brad Fitzpatrick
parent 393f84a125
commit 21fa1481c3
1 changed files with 22 additions and 9 deletions
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31
src/cmd/internal/obj/x86/asm6.go
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@ -65,6 +65,19 @@ const (
maxLoopPad = 0
)
// Bit flags that are used to express jump target properties.
const (
// branchBackwards marks targets that are located behind.
// Used to express jumps to loop headers.
branchBackwards = (1 << iota)
// branchShort marks branches those target is close,
// with offset is in -128..127 range.
branchShort
// branchLoopHead marks loop entry.
// Used to insert padding for misaligned loops.
branchLoopHead
)
type Optab struct {
as obj.As
ytab []ytab
@ -2125,11 +2138,11 @@ func span6(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) {
var count int64 // rough count of number of instructions
for p := s.Func.Text; p != nil; p = p.Link {
count++
p.Back = 2 // use short branches first time through
p.Back = branchShort // use short branches first time through
q = p.Pcond
if q != nil && (q.Back&2 != 0) {
p.Back |= 1 // backward jump
q.Back |= 4 // loop head
if q != nil && (q.Back&branchShort != 0) {
p.Back |= branchBackwards
q.Back |= branchLoopHead
}
if p.As == AADJSP {
@ -2197,7 +2210,7 @@ func span6(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) {
}
}
if (p.Back&4 != 0) && c&(loopAlign-1) != 0 {
if (p.Back&branchLoopHead != 0) && c&(loopAlign-1) != 0 {
// pad with NOPs
v := -c & (loopAlign - 1)
@ -2213,10 +2226,10 @@ func span6(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) {
// process forward jumps to p
for q = p.Rel; q != nil; q = q.Forwd {
v := int32(p.Pc - (q.Pc + int64(q.Isize)))
if q.Back&2 != 0 { // short
if q.Back&branchShort != 0 {
if v > 127 {
loop++
q.Back ^= 2
q.Back ^= branchShort
}
if q.As == AJCXZL || q.As == AXBEGIN {
@ -4328,7 +4341,7 @@ func (ab *AsmBuf) doasm(ctxt *obj.Link, cursym *obj.LSym, p *obj.Prog) {
log.Fatalf("bad code")
}
if p.Back&1 != 0 {
if p.Back&branchBackwards != 0 {
v = q.Pc - (p.Pc + 2)
if v >= -128 && p.As != AXBEGIN {
if p.As == AJCXZL {
@ -4358,7 +4371,7 @@ func (ab *AsmBuf) doasm(ctxt *obj.Link, cursym *obj.LSym, p *obj.Prog) {
p.Forwd = q.Rel
q.Rel = p
if p.Back&2 != 0 && p.As != AXBEGIN { // short
if p.Back&branchShort != 0 && p.As != AXBEGIN {
if p.As == AJCXZL {
ab.Put1(0x67)
}