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[dev.ssa] cmd/compile: use MOVWaddr for address on ARM

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Introduce an op MOVWaddr for addresses on ARM, instead of overuse
ADDconst.

Mark MOVWaddr as rematerializable. This fixes a liveness problem: if
it were not rematerializable, the address of a variable may be spilled
and later use of the address may just load the spilled value without
mentioning the variable, and the liveness code may think it is dead
prematurely.

Update #15365.

Change-Id: Ib0b0fa826bdb75c9e6bb362b95c6cf132cc6b1c0
Reviewed-on: https://go-review.googlesource.com/23942
Reviewed-by: David Chase <drchase@google.com>
This commit is contained in:
Cherry Zhang 2016-06-06 22:36:45 -04:00
parent e3a6d00876
commit c40dcff2f2
5 changed files with 426 additions and 93 deletions
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73
src/cmd/compile/internal/arm/ssa.go
View file

@ -295,37 +295,8 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
p.Reg = r1
p.To.Type = obj.TYPE_REG
p.To.Reg = r
case ssa.OpARMADDconst:
if v.Aux != nil {
switch v.Aux.(type) {
default:
v.Fatalf("aux is of unknown type %T", v.Aux)
case *ssa.ExternSymbol:
reg := v.Args[0].Block.Func.RegAlloc[v.Args[0].ID].(*ssa.Register)
if reg.Name() != "SB" {
v.Fatalf("extern symbol with non-SB base register %s", reg.Name())
}
case *ssa.ArgSymbol,
*ssa.AutoSymbol:
reg := v.Args[0].Block.Func.RegAlloc[v.Args[0].ID].(*ssa.Register)
if reg.Name() != "SP" {
v.Fatalf("arg/auto symbol with non-SP base register %s", reg.Name())
}
}
// MOVW $sym+off(base), R
// the assembler expands it as the following:
// - base is SP: add constant offset to SP (R13)
// when constant is large, tmp register (R11) may be used
// - base is SB: load external address from constant pool (use relocation)
p := gc.Prog(arm.AMOVW)
p.From.Type = obj.TYPE_ADDR
gc.AddAux(&p.From, v)
p.To.Type = obj.TYPE_REG
p.To.Reg = gc.SSARegNum(v)
break
}
fallthrough
case ssa.OpARMSUBconst,
case ssa.OpARMADDconst,
ssa.OpARMSUBconst,
ssa.OpARMRSBconst,
ssa.OpARMANDconst,
ssa.OpARMORconst,
@ -407,6 +378,46 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
p.From.Type = obj.TYPE_CONST
p.From.Offset = v.AuxInt
p.Reg = gc.SSARegNum(v.Args[0])
case ssa.OpARMMOVWaddr:
if v.Aux == nil {
// MOVW $off(SP), R
reg := v.Args[0].Block.Func.RegAlloc[v.Args[0].ID].(*ssa.Register)
if reg.Name() != "SP" {
v.Fatalf("arg/auto symbol with non-SP base register %s", reg.Name())
}
p := gc.Prog(arm.AMOVW)
p.From.Type = obj.TYPE_ADDR
p.From.Reg = arm.REGSP
p.From.Offset = v.AuxInt
p.To.Type = obj.TYPE_REG
p.To.Reg = gc.SSARegNum(v)
break
}
// MOVW $sym+off(base), R
// the assembler expands it as the following:
// - base is SP: add constant offset to SP (R13)
// when constant is large, tmp register (R11) may be used
// - base is SB: load external address from constant pool (use relocation)
switch v.Aux.(type) {
default:
v.Fatalf("aux is of unknown type %T", v.Aux)
case *ssa.ExternSymbol:
reg := v.Args[0].Block.Func.RegAlloc[v.Args[0].ID].(*ssa.Register)
if reg.Name() != "SB" {
v.Fatalf("extern symbol with non-SB base register %s", reg.Name())
}
case *ssa.ArgSymbol,
*ssa.AutoSymbol:
reg := v.Args[0].Block.Func.RegAlloc[v.Args[0].ID].(*ssa.Register)
if reg.Name() != "SP" {
v.Fatalf("arg/auto symbol with non-SP base register %s", reg.Name())
}
}
p := gc.Prog(arm.AMOVW)
p.From.Type = obj.TYPE_ADDR
gc.AddAux(&p.From, v)
p.To.Type = obj.TYPE_REG
p.To.Reg = gc.SSARegNum(v)
case ssa.OpARMMOVBload,
ssa.OpARMMOVBUload,
ssa.OpARMMOVHload,