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cmd/compile: remove branch in atomicCas{32,64} sequence on ppc64x. 

This removes one of the branches in the atomicCas sequences for
ppc64/ppc64le.

Change-Id: Ibb46fbfdce052889c69e3da298f28caff540d99b
Reviewed-on: https://go-review.googlesource.com/c/go/+/422014
Reviewed-by: Archana Ravindar <aravind5@in.ibm.com>
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Lynn Boger <laboger@linux.vnet.ibm.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Paul Murphy <murp@ibm.com>
This commit is contained in:
Lynn Boger 2022-08-02 08:26:23 -05:00
parent afd792feb5
commit 62125c9b79
1 changed files with 19 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

44
src/cmd/compile/internal/ppc64/ssa.go
View File

@ -357,18 +357,16 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
case ssa.OpPPC64LoweredAtomicCas64,
ssa.OpPPC64LoweredAtomicCas32:
// MOVD $0, Rout
// LWSYNC
// loop:
// LDAR (Rarg0), MutexHint, Rtmp
// CMP Rarg1, Rtmp
// BNE fail
// BNE end
// STDCCC Rarg2, (Rarg0)
// BNE loop
// LWSYNC // Only for sequential consistency; not required in CasRel.
// MOVD $1, Rout
// BR end
// fail:
// MOVD $0, Rout
// end:
ld := ppc64.ALDAR
st := ppc64.ASTDCCC
@ -382,20 +380,26 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
r1 := v.Args[1].Reg()
r2 := v.Args[2].Reg()
out := v.Reg0()
// Initialize return value to false
p := s.Prog(ppc64.AMOVD)
p.From.Type = obj.TYPE_CONST
p.From.Offset = 0
p.To.Type = obj.TYPE_REG
p.To.Reg = out
// LWSYNC - Assuming shared data not write-through-required nor
// caching-inhibited. See Appendix B.2.2.2 in the ISA 2.07b.
plwsync1 := s.Prog(ppc64.ALWSYNC)
plwsync1.To.Type = obj.TYPE_NONE
// LDAR or LWAR
p := s.Prog(ld)
p.From.Type = obj.TYPE_MEM
p.From.Reg = r0
p.To.Type = obj.TYPE_REG
p.To.Reg = ppc64.REGTMP
p0 := s.Prog(ld)
p0.From.Type = obj.TYPE_MEM
p0.From.Reg = r0
p0.To.Type = obj.TYPE_REG
p0.To.Reg = ppc64.REGTMP
// If it is a Compare-and-Swap-Release operation, set the EH field with
// the release hint.
if v.AuxInt == 0 {
p.SetFrom3Const(0)
p0.SetFrom3Const(0)
}
// CMP reg1,reg2
p1 := s.Prog(cmp)
@ -403,7 +407,7 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
p1.From.Reg = r1
p1.To.Reg = ppc64.REGTMP
p1.To.Type = obj.TYPE_REG
// BNE cas_fail
// BNE done with return value = false
p2 := s.Prog(ppc64.ABNE)
p2.To.Type = obj.TYPE_BRANCH
// STDCCC or STWCCC
@ -415,7 +419,7 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
// BNE retry
p4 := s.Prog(ppc64.ABNE)
p4.To.Type = obj.TYPE_BRANCH
p4.To.SetTarget(p)
p4.To.SetTarget(p0)
// LWSYNC - Assuming shared data not write-through-required nor
// caching-inhibited. See Appendix B.2.1.1 in the ISA 2.07b.
// If the operation is a CAS-Release, then synchronization is not necessary.
@ -423,25 +427,15 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
plwsync2 := s.Prog(ppc64.ALWSYNC)
plwsync2.To.Type = obj.TYPE_NONE
}
// return true
// return value true
p5 := s.Prog(ppc64.AMOVD)
p5.From.Type = obj.TYPE_CONST
p5.From.Offset = 1
p5.To.Type = obj.TYPE_REG
p5.To.Reg = out
// BR done
p6 := s.Prog(obj.AJMP)
p6.To.Type = obj.TYPE_BRANCH
// return false
p7 := s.Prog(ppc64.AMOVD)
p7.From.Type = obj.TYPE_CONST
p7.From.Offset = 0
p7.To.Type = obj.TYPE_REG
p7.To.Reg = out
p2.To.SetTarget(p7)
// done (label)
p8 := s.Prog(obj.ANOP)
p6.To.SetTarget(p8)
p6 := s.Prog(obj.ANOP)
p2.To.SetTarget(p6)
case ssa.OpPPC64LoweredPubBarrier:
// LWSYNC