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[dev.ssa] cmd/compile: fix possible invalid pointer spill in large Zero/Move on ARM

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Instead of comparing the address of the end of the memory to zero/copy,
comparing the address of the last element, which is a valid pointer.
Also unify large and unaligned Zero/Move, by passing alignment as AuxInt.

Fixes #16515 for ARM.

Change-Id: I19a62b31c5acf5c55c16a89bea1039c926dc91e5
Reviewed-on: https://go-review.googlesource.com/25300
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
This commit is contained in:
Cherry Zhang 2016-07-27 12:33:08 -04:00
parent 83208504fe
commit 114c05962c
5 changed files with 68 additions and 154 deletions
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48
src/cmd/compile/internal/arm/ssa.go
View file

@ -797,7 +797,7 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
}
return
}
case ssa.OpARMDUFFZERO, ssa.OpARMLoweredZero, ssa.OpARMLoweredZeroU:
case ssa.OpARMDUFFZERO, ssa.OpARMLoweredZero:
// arg0 is ptr
if w.Args[0] == v.Args[0] {
if gc.Debug_checknil != 0 && int(v.Line) > 1 {
@ -805,7 +805,7 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
}
return
}
case ssa.OpARMDUFFCOPY, ssa.OpARMLoweredMove, ssa.OpARMLoweredMoveU:
case ssa.OpARMDUFFCOPY, ssa.OpARMLoweredMove:
// arg0 is dst ptr, arg1 is src ptr
if w.Args[0] == v.Args[0] || w.Args[1] == v.Args[0] {
if gc.Debug_checknil != 0 && int(v.Line) > 1 {
@ -835,15 +835,23 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
if gc.Debug_checknil != 0 && v.Line > 1 { // v.Line==1 in generated wrappers
gc.Warnl(v.Line, "generated nil check")
}
case ssa.OpARMLoweredZero, ssa.OpARMLoweredZeroU:
case ssa.OpARMLoweredZero:
// MOVW.P Rarg2, 4(R1)
// CMP Rarg1, R1
// BLT -2(PC)
// arg1 is the end of memory to zero
// BLE -2(PC)
// arg1 is the address of the last element to zero
// arg2 is known to be zero
var sz int64 = 4
mov := arm.AMOVW
if v.Op == ssa.OpARMLoweredZeroU { // unaligned
// auxint is alignment
var sz int64
var mov obj.As
switch {
case v.AuxInt%4 == 0:
sz = 4
mov = arm.AMOVW
case v.AuxInt%2 == 0:
sz = 2
mov = arm.AMOVH
default:
sz = 1
mov = arm.AMOVB
}
@ -858,18 +866,26 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
p2.From.Type = obj.TYPE_REG
p2.From.Reg = gc.SSARegNum(v.Args[1])
p2.Reg = arm.REG_R1
p3 := gc.Prog(arm.ABLT)
p3 := gc.Prog(arm.ABLE)
p3.To.Type = obj.TYPE_BRANCH
gc.Patch(p3, p)
case ssa.OpARMLoweredMove, ssa.OpARMLoweredMoveU:
case ssa.OpARMLoweredMove:
// MOVW.P 4(R1), Rtmp
// MOVW.P Rtmp, 4(R2)
// CMP Rarg2, R1
// BLT -3(PC)
// arg2 is the end of src
var sz int64 = 4
mov := arm.AMOVW
if v.Op == ssa.OpARMLoweredMoveU { // unaligned
// BLE -3(PC)
// arg2 is the address of the last element of src
// auxint is alignment
var sz int64
var mov obj.As
switch {
case v.AuxInt%4 == 0:
sz = 4
mov = arm.AMOVW
case v.AuxInt%2 == 0:
sz = 2
mov = arm.AMOVH
default:
sz = 1
mov = arm.AMOVB
}
@ -891,7 +907,7 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
p3.From.Type = obj.TYPE_REG
p3.From.Reg = gc.SSARegNum(v.Args[2])
p3.Reg = arm.REG_R1
p4 := gc.Prog(arm.ABLT)
p4 := gc.Prog(arm.ABLE)
p4.To.Type = obj.TYPE_BRANCH
gc.Patch(p4, p)
case ssa.OpVarDef: