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cmd/compile/internal/ssa: only store relevant slots in pendingEntries 

For functions with many local variables, keeping track of every
LocalSlot for every variable is very expensive. Only track the slots
that are actually used by a given variable.

Change-Id: Iaafbce030a782b8b8c4a0eb7cf025e59af899ea4
Reviewed-on: https://go-review.googlesource.com/92400
Reviewed-by: David Chase <drchase@google.com>
This commit is contained in:
Heschi Kreinick 2018-01-31 16:30:16 -05:00
parent a306341db7
commit 9c854d65a3
1 changed files with 22 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

37
src/cmd/compile/internal/ssa/debug.go
View File

@ -214,10 +214,14 @@ func (state *debugState) initializeCache() {
state.changedVars = make([]bool, len(state.vars))
// A pending entry per user variable, with space to track each of its pieces.
if want := len(state.vars) * len(state.slots); cap(state.cache.pendingSlotLocs) < want {
state.cache.pendingSlotLocs = make([]VarLoc, want)
nPieces := 0
for i := range state.varSlots {
nPieces += len(state.varSlots[i])
}
psl := state.cache.pendingSlotLocs[:len(state.vars)*len(state.slots)]
if cap(state.cache.pendingSlotLocs) < nPieces {
state.cache.pendingSlotLocs = make([]VarLoc, nPieces)
}
psl := state.cache.pendingSlotLocs[:nPieces]
for i := range psl {
psl[i] = VarLoc{}
}
@ -225,10 +229,12 @@ func (state *debugState) initializeCache() {
state.cache.pendingEntries = make([]pendingEntry, len(state.vars))
}
pe := state.cache.pendingEntries[:len(state.vars)]
for varID := range pe {
freePieceIdx := 0
for varID, slots := range state.varSlots {
pe[varID] = pendingEntry{
pieces: state.cache.pendingSlotLocs[varID*len(state.slots) : (varID+1)*len(state.slots)],
pieces: state.cache.pendingSlotLocs[freePieceIdx : freePieceIdx+len(slots)],
}
freePieceIdx += len(slots)
}
}
@ -657,9 +663,8 @@ func (a partsByVarOffset) Swap(i, j int) { a.slotIDs[i], a.slotIDs[j] = a.slotID
type pendingEntry struct {
present bool
startBlock, startValue ID
// The location of each piece of the variable, indexed by *SlotID*,
// even though only a few slots are used in each entry. This could be
// improved by only storing the relevant slots.
// The location of each piece of the variable, in the same order as the
// SlotIDs in varParts.
pieces []VarLoc
}
@ -736,14 +741,14 @@ func (state *debugState) buildLocationLists(Ctxt *obj.Link, blockLocs []*BlockDe
if state.loggingEnabled {
var partStrs []string
for _, slot := range state.varSlots[varID] {
partStrs = append(partStrs, fmt.Sprintf("%v@%v", state.slots[slot], state.LocString(pending.pieces[slot])))
for i, slot := range state.varSlots[varID] {
partStrs = append(partStrs, fmt.Sprintf("%v@%v", state.slots[slot], state.LocString(pending.pieces[i])))
}
state.logf("Add entry for %v: \tb%vv%v-b%vv%v = \t%v\n", state.vars[varID], pending.startBlock, pending.startValue, endBlock, endValue, strings.Join(partStrs, " "))
}
for _, slotID := range state.varSlots[varID] {
loc := pending.pieces[slotID]
for i, slotID := range state.varSlots[varID] {
loc := pending.pieces[i]
slot := state.slots[slotID]
if !loc.absent() {
@ -795,8 +800,8 @@ func (state *debugState) buildLocationLists(Ctxt *obj.Link, blockLocs []*BlockDe
// Extend the previous entry if possible.
if pending.present {
merge := true
for _, slotID := range state.varSlots[varID] {
if !canMerge(pending.pieces[slotID], curLoc[slotID]) {
for i, slotID := range state.varSlots[varID] {
if !canMerge(pending.pieces[i], curLoc[slotID]) {
merge = false
break
}
@ -810,7 +815,9 @@ func (state *debugState) buildLocationLists(Ctxt *obj.Link, blockLocs []*BlockDe
pending.present = true
pending.startBlock = v.Block.ID
pending.startValue = v.ID
copy(pending.pieces, curLoc)
for i, slot := range state.varSlots[varID] {
pending.pieces[i] = curLoc[slot]
}
return
}