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cmd/compile: rename issafepoint -> hasStackMap

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Currently, this function conflates two (easily conflated!) concepts:
whether a Value is a safe-point and whether it has a stack map. In
particular, call Values may not be a safe-point, but may need a stack
map anyway in case the called function grows the stack.

Hence, rename this function to "hasStackMap", since that's really what
it represents.

For #36365.

Change-Id: I89839de0be8db3be3f0d3a7fb5fcf0b0b6ebc98a
Reviewed-on: https://go-review.googlesource.com/c/go/+/230540
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This commit is contained in:
Austin Clements 2020-04-17 17:14:33 -04:00
parent 2bad2f7eba
commit a6deafaf9e
1 changed files with 12 additions and 9 deletions
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21
src/cmd/compile/internal/gc/plive.go
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@ -646,7 +646,7 @@ func (lv *Liveness) pointerMap(liveout bvec, vars []*Node, args, locals bvec) {
func (lv *Liveness) markUnsafePoints() {
if compiling_runtime || lv.f.NoSplit {
// No complex analysis necessary. Do this on the fly
// in issafepoint.
// in hasStackMap.
return
}
@ -801,9 +801,12 @@ func (lv *Liveness) markUnsafePoints() {
}
}
// Returns true for instructions that are safe points that must be annotated
// with liveness information.
func (lv *Liveness) issafepoint(v *ssa.Value) bool {
// Returns true for instructions that must have a stack map.
//
// This does not necessarily mean the instruction is a safe-point. In
// particular, call Values can have a stack map in case the callee
// grows the stack, but not themselves be a safe-point.
func (lv *Liveness) hasStackMap(v *ssa.Value) bool {
// The runtime was written with the assumption that
// safe-points only appear at call sites (because that's how
// it used to be). We could and should improve that, but for
@ -1049,7 +1052,7 @@ func (lv *Liveness) epilogue() {
// Walk forward through the basic block instructions and
// allocate liveness maps for those instructions that need them.
for _, v := range b.Values {
if !lv.issafepoint(v) {
if !lv.hasStackMap(v) {
continue
}
@ -1064,7 +1067,7 @@ func (lv *Liveness) epilogue() {
for i := len(b.Values) - 1; i >= 0; i-- {
v := b.Values[i]
if lv.issafepoint(v) {
if lv.hasStackMap(v) {
// Found an interesting instruction, record the
// corresponding liveness information.
@ -1113,7 +1116,7 @@ func (lv *Liveness) epilogue() {
// of the context register, so it's dead after the call.
index = int32(firstBitmapIndex)
for _, v := range b.Values {
if lv.issafepoint(v) {
if lv.hasStackMap(v) {
live := lv.livevars[index]
if v.Op.IsCall() && live.regs != 0 {
lv.printDebug()
@ -1185,7 +1188,7 @@ func (lv *Liveness) compact(b *ssa.Block) {
pos++
}
for _, v := range b.Values {
if lv.issafepoint(v) {
if lv.hasStackMap(v) {
lv.livenessMap.set(v, add(lv.livevars[pos]))
pos++
}
@ -1360,7 +1363,7 @@ func (lv *Liveness) printDebug() {
fmt.Printf("\n")
}
if !lv.issafepoint(v) {
if !lv.hasStackMap(v) {
continue
}