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cmd/internal/obj/x86: minor clean-up in span6

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* Reduce the scope of q.
* Remove duplicate handling of AADJSP.
* Move ab declaration closer to use.
* Collapse nested if statements.
* Change declaration of n for increased readability in context.
* Simplify AADJSP handling.

Passes toolstash-check.

Change-Id: I046369477db567f2f7c4a9c8d400ec9dd9c32f3f
Reviewed-on: https://go-review.googlesource.com/c/go/+/168342
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This commit is contained in:
Josh Bleecher Snyder 2019-03-18 07:33:43 -07:00
parent e608ffda08
commit fc1e6915dc
1 changed files with 13 additions and 38 deletions
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51
src/cmd/internal/obj/x86/asm6.go
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@ -1857,63 +1857,38 @@ func span6(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) {
ctxt.Diag("x86 tables not initialized, call x86.instinit first")
}
var ab AsmBuf
for p := s.Func.Text; p != nil; p = p.Link {
if p.To.Type == obj.TYPE_BRANCH {
if p.Pcond == nil {
p.Pcond = p
}
if p.To.Type == obj.TYPE_BRANCH && p.Pcond == nil {
p.Pcond = p
}
if p.As == AADJSP {
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_SP
v := int32(-p.From.Offset)
p.From.Offset = int64(v)
p.As = spadjop(ctxt, AADDL, AADDQ)
if v < 0 {
p.As = spadjop(ctxt, ASUBL, ASUBQ)
v = -v
p.From.Offset = int64(v)
}
if v == 0 {
switch v := p.From.Offset; {
case v == 0:
p.As = obj.ANOP
case v < 0:
p.As = spadjop(ctxt, AADDL, AADDQ)
p.From.Offset *= -1
default:
p.As = spadjop(ctxt, ASUBL, ASUBQ)
}
}
}
var q *obj.Prog
var count int64 // rough count of number of instructions
for p := s.Func.Text; p != nil; p = p.Link {
count++
p.Back = branchShort // use short branches first time through
q = p.Pcond
if q != nil && (q.Back&branchShort != 0) {
if q := p.Pcond; q != nil && (q.Back&branchShort != 0) {
p.Back |= branchBackwards
q.Back |= branchLoopHead
}
if p.As == AADJSP {
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_SP
v := int32(-p.From.Offset)
p.From.Offset = int64(v)
p.As = spadjop(ctxt, AADDL, AADDQ)
if v < 0 {
p.As = spadjop(ctxt, ASUBL, ASUBQ)
v = -v
p.From.Offset = int64(v)
}
if v == 0 {
p.As = obj.ANOP
}
}
}
s.GrowCap(count * 5) // preallocate roughly 5 bytes per instruction
n := 0
var ab AsmBuf
var n int
var c int32
errors := ctxt.Errors
for {
@ -1975,7 +1950,7 @@ func span6(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) {
p.Pc = int64(c)
// process forward jumps to p
for q = p.Rel; q != nil; q = q.Forwd {
for q := p.Rel; q != nil; q = q.Forwd {
v := int32(p.Pc - (q.Pc + int64(q.Isize)))
if q.Back&branchShort != 0 {
if v > 127 {