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cmd/compile: use opregreg for x86.AXOR* ops

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Change-Id: Id087d86261744559685c687aa7bad6c55466f1b5
Reviewed-on: https://go-review.googlesource.com/c/go/+/369020
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Trust: Alex Rakoczy <alex@golang.org>
This commit is contained in:
nimelehin 2021-12-06 11:46:57 +03:00 committed by Keith Randall
parent 6a40bdcbaf
commit a4ffeb9edd
1 changed files with 4 additions and 20 deletions
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24
src/cmd/compile/internal/amd64/ssa.go
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@ -288,11 +288,7 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
r := v.Args[1].Reg()
// Zero extend dividend.
c := s.Prog(x86.AXORL)
c.From.Type = obj.TYPE_REG
c.From.Reg = x86.REG_DX
c.To.Type = obj.TYPE_REG
c.To.Reg = x86.REG_DX
opregreg(s, x86.AXORL, x86.REG_DX, x86.REG_DX)
// Issue divide.
p := s.Prog(v.Op.Asm())
@ -362,11 +358,7 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
n1.To.Reg = x86.REG_AX
// n % -1 == 0
n2 := s.Prog(x86.AXORL)
n2.From.Type = obj.TYPE_REG
n2.From.Reg = x86.REG_DX
n2.To.Type = obj.TYPE_REG
n2.To.Reg = x86.REG_DX
opregreg(s, x86.AXORL, x86.REG_DX, x86.REG_DX)
// TODO(khr): issue only the -1 fixup code we need.
// For instance, if only the quotient is used, no point in zeroing the remainder.
@ -744,11 +736,7 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
// If flags aren't live (indicated by v.Aux == nil),
// then we can rewrite MOV $0, AX into XOR AX, AX.
if v.AuxInt == 0 && v.Aux == nil {
p := s.Prog(x86.AXORL)
p.From.Type = obj.TYPE_REG
p.From.Reg = x
p.To.Type = obj.TYPE_REG
p.To.Reg = x
opregreg(s, x86.AXORL, x, x)
break
}
@ -1142,11 +1130,7 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
// POPCNT/TZCNT/LZCNT have a false dependency on the destination register on Intel cpus.
// TZCNT/LZCNT problem affects pre-Skylake models. See discussion at https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62011#c7.
// Xor register with itself to break the dependency.
p := s.Prog(x86.AXORL)
p.From.Type = obj.TYPE_REG
p.From.Reg = v.Reg()
p.To.Type = obj.TYPE_REG
p.To.Reg = v.Reg()
opregreg(s, x86.AXORL, v.Reg(), v.Reg())
}
p := s.Prog(v.Op.Asm())
p.From.Type = obj.TYPE_REG