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cmd/compile: not use REGTMP in ZeroRange on ARM64

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For async preemption, we will be using REGTMP as a temporary
register in injected call on ARM64, which will clobber it. So any
code that uses REGTMP is not safe for async preemption.

For ZeroRange, which is inserted at the function entry where
there is no register live, we could just use a different register
and avoid REGTMP.

Change-Id: I3db763828df6846908c9843a9912597efb9efcdf
Reviewed-on: https://go-review.googlesource.com/c/go/+/203458
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
This commit is contained in:
Cherry Zhang 2019-10-25 00:50:00 -04:00
parent 2ff746d7dc
commit 0f992b9948
2 changed files with 14 additions and 6 deletions
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12
src/cmd/compile/internal/arm64/ggen.go
View File

@ -44,12 +44,16 @@ func zerorange(pp *gc.Progs, p *obj.Prog, off, cnt int64, _ *uint32) *obj.Prog {
p.To.Sym = gc.Duffzero
p.To.Offset = 4 * (64 - cnt/(2*int64(gc.Widthptr)))
} else {
p = pp.Appendpp(p, arm64.AMOVD, obj.TYPE_CONST, 0, 8+off-8, obj.TYPE_REG, arm64.REGTMP, 0)
// Not using REGTMP, so this is async preemptible (async preemption clobbers REGTMP).
// We are at the function entry, where no register is live, so it is okay to clobber
// other registers
const rtmp = arm64.REG_R20
p = pp.Appendpp(p, arm64.AMOVD, obj.TYPE_CONST, 0, 8+off-8, obj.TYPE_REG, rtmp, 0)
p = pp.Appendpp(p, arm64.AMOVD, obj.TYPE_REG, arm64.REGSP, 0, obj.TYPE_REG, arm64.REGRT1, 0)
p = pp.Appendpp(p, arm64.AADD, obj.TYPE_REG, arm64.REGTMP, 0, obj.TYPE_REG, arm64.REGRT1, 0)
p = pp.Appendpp(p, arm64.AADD, obj.TYPE_REG, rtmp, 0, obj.TYPE_REG, arm64.REGRT1, 0)
p.Reg = arm64.REGRT1
p = pp.Appendpp(p, arm64.AMOVD, obj.TYPE_CONST, 0, cnt, obj.TYPE_REG, arm64.REGTMP, 0)
p = pp.Appendpp(p, arm64.AADD, obj.TYPE_REG, arm64.REGTMP, 0, obj.TYPE_REG, arm64.REGRT2, 0)
p = pp.Appendpp(p, arm64.AMOVD, obj.TYPE_CONST, 0, cnt, obj.TYPE_REG, rtmp, 0)
p = pp.Appendpp(p, arm64.AADD, obj.TYPE_REG, rtmp, 0, obj.TYPE_REG, arm64.REGRT2, 0)
p.Reg = arm64.REGRT1
p = pp.Appendpp(p, arm64.AMOVD, obj.TYPE_REG, arm64.REGZERO, 0, obj.TYPE_MEM, arm64.REGRT1, int64(gc.Widthptr))
p.Scond = arm64.C_XPRE

4
src/cmd/compile/internal/gc/go.go
View File

@ -257,7 +257,11 @@ type Arch struct {
SoftFloat bool
PadFrame func(int64) int64
// ZeroRange zeroes a range of memory on stack. It is only inserted
// at function entry, and it is ok to clobber registers.
ZeroRange func(*Progs, *obj.Prog, int64, int64, *uint32) *obj.Prog
Ginsnop func(*Progs) *obj.Prog
Ginsnopdefer func(*Progs) *obj.Prog // special ginsnop for deferreturn