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runtime: remove legacy eager write barrier

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Now that the buffered write barrier is implemented for all
architectures, we can remove the old eager write barrier
implementation. This CL removes the implementation from the runtime,
support in the compiler for calling it, and updates some compiler
tests that relied on the old eager barrier support. It also makes sure
that all of the useful comments from the old write barrier
implementation still have a place to live.

Fixes #22460.

Updates #21640 since this fixes the layering concerns of the write
barrier (but not the other things in that issue).

Change-Id: I580f93c152e89607e0a72fe43370237ba97bae74
Reviewed-on: https://go-review.googlesource.com/92705
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Rick Hudson <rlh@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Austin Clements 2018-01-15 12:27:17 -05:00
parent 245310883d
commit 2010189407
24 changed files with 128 additions and 250 deletions
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19
src/cmd/compile/internal/ssa/writebarrier.go
View file

@ -31,7 +31,7 @@ func needwb(v *Value) bool {
// and runtime calls, like
//
// if writeBarrier.enabled {
// writebarrierptr(ptr, val)
// gcWriteBarrier(ptr, val) // Not a regular Go call
// } else {
// *ptr = val
// }
@ -44,7 +44,7 @@ func writebarrier(f *Func) {
}
var sb, sp, wbaddr, const0 *Value
var writebarrierptr, typedmemmove, typedmemclr, gcWriteBarrier *obj.LSym
var typedmemmove, typedmemclr, gcWriteBarrier *obj.LSym
var stores, after []*Value
var sset *sparseSet
var storeNumber []int32
@ -96,10 +96,7 @@ func writebarrier(f *Func) {
}
wbsym := f.fe.Syslook("writeBarrier")
wbaddr = f.Entry.NewValue1A(initpos, OpAddr, f.Config.Types.UInt32Ptr, wbsym, sb)
writebarrierptr = f.fe.Syslook("writebarrierptr")
if !f.fe.Debug_eagerwb() {
gcWriteBarrier = f.fe.Syslook("gcWriteBarrier")
}
gcWriteBarrier = f.fe.Syslook("gcWriteBarrier")
typedmemmove = f.fe.Syslook("typedmemmove")
typedmemclr = f.fe.Syslook("typedmemclr")
const0 = f.ConstInt32(initpos, f.Config.Types.UInt32, 0)
@ -198,7 +195,6 @@ func writebarrier(f *Func) {
var val *Value
switch w.Op {
case OpStoreWB:
fn = writebarrierptr
val = w.Args[1]
nWBops--
case OpMoveWB:
@ -217,11 +213,13 @@ func writebarrier(f *Func) {
switch w.Op {
case OpStoreWB, OpMoveWB, OpZeroWB:
volatile := w.Op == OpMoveWB && isVolatile(val)
if w.Op == OpStoreWB && !f.fe.Debug_eagerwb() {
if w.Op == OpStoreWB {
memThen = bThen.NewValue3A(pos, OpWB, types.TypeMem, gcWriteBarrier, ptr, val, memThen)
} else {
memThen = wbcall(pos, bThen, fn, typ, ptr, val, memThen, sp, sb, volatile)
}
// Note that we set up a writebarrier function call.
f.fe.SetWBPos(pos)
case OpVarDef, OpVarLive, OpVarKill:
memThen = bThen.NewValue1A(pos, w.Op, types.TypeMem, w.Aux, memThen)
}
@ -239,11 +237,6 @@ func writebarrier(f *Func) {
case OpVarDef, OpVarLive, OpVarKill:
memElse = bElse.NewValue1A(pos, w.Op, types.TypeMem, w.Aux, memElse)
}
if fn != nil {
// Note that we set up a writebarrier function call.
f.fe.SetWBPos(pos)
}
}
// merge memory