Stowage/go
2
0
Fork 0
mirror of https://github.com/golang/go.git synced 2025-12-08 06:10:04 +00:00
Code Issues Projects Releases Packages Wiki Activity

cmd/compile: relax liveness restrictions on ambiguously live

Browse source 
Update gc liveness to remove special conservative treatment
of ambiguously live vars, since there is no longer a need to
protect against GCDEBUG=gcdead.

Change-Id: Id6e2d03218f7d67911e8436d283005a124e6957f
Reviewed-on: https://go-review.googlesource.com/24896
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
This commit is contained in:
Than McIntosh 2016-07-14 13:23:11 -04:00 • committed by Ian Lance Taylor
parent 5f36e9a306
commit 6c5e377d23
2 changed files with 18 additions and 23 deletions
Download patch file Download diff file Expand all files Collapse all files

22
src/cmd/compile/internal/gc/plive.go
View file

@ -1188,17 +1188,18 @@ func livenessepilogue(lv *Liveness) {
avarinit := bvalloc(nvars)
any := bvalloc(nvars)
all := bvalloc(nvars)
ambig := bvalloc(localswords())
pparamout := bvalloc(localswords())
// Set ambig bit for the pointers to heap-allocated pparamout variables.
// These are implicitly read by post-deferreturn code and thus must be
// kept live throughout the function (if there is any defer that recovers).
// Record pointers to heap-allocated pparamout variables. These
// are implicitly read by post-deferreturn code and thus must be
// kept live throughout the function (if there is any defer that
// recovers).
if hasdefer {
for _, n := range lv.vars {
if n.IsOutputParamHeapAddr() {
n.Name.Needzero = true
xoffset := n.Xoffset + stkptrsize
onebitwalktype1(n.Type, &xoffset, ambig)
onebitwalktype1(n.Type, &xoffset, pparamout)
}
}
}
@ -1250,11 +1251,6 @@ func livenessepilogue(lv *Liveness) {
if debuglive >= 1 {
Warnl(p.Lineno, "%v: %L is ambiguously live", Curfn.Func.Nname, n)
}
// Record in 'ambiguous' bitmap.
xoffset := n.Xoffset + stkptrsize
onebitwalktype1(n.Type, &xoffset, ambig)
}
}
}
@ -1355,11 +1351,9 @@ func livenessepilogue(lv *Liveness) {
locals := lv.livepointers[pos]
onebitlivepointermap(lv, liveout, lv.vars, args, locals)
// Ambiguously live variables are zeroed immediately after
// function entry. Mark them live for all the non-entry bitmaps
// so that GODEBUG=gcdead=1 mode does not poison them.
// Mark pparamout variables (as described above)
if p.As == obj.ACALL {
bvor(locals, locals, ambig)
bvor(locals, locals, pparamout)
}
// Show live pointer bitmaps.