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cmd/compile: reimplement location list generation

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Completely redesign and reimplement location list generation to be more
efficient, and hopefully not too hard to understand.

RegKills are gone. Instead of using the regalloc's liveness
calculations, redo them using the Ops' clobber information. Besides
saving a lot of Values, this avoids adding RegKills to blocks that would
be empty otherwise, which was messing up optimizations. This does mean
that it's much harder to tell whether the generation process is buggy
(there's nothing to cross-check it with), and there may be disagreements
with GC liveness. But the performance gain is significant, and it's nice
not to be messing with earlier compiler phases.

The intermediate representations are gone. Instead of producing
ssa.BlockDebugs, then dwarf.LocationLists, and then finally real
location lists, go directly from the SSA to a (mostly) real location
list. Because the SSA analysis happens before assembly, it stores
encoded block/value IDs where PCs would normally go. It would be easier
to do the SSA analysis after assembly, but I didn't want to retain the
SSA just for that.

Generation proceeds in two phases: first, it traverses the function in
CFG order, storing the state of the block at the beginning and end. End
states are used to produce the start states of the successor blocks. In
the second phase, it traverses in program text order and produces the
location lists. The processing in the second phase is redundant, but
much cheaper than storing the intermediate representation. It might be
possible to combine the two phases somewhat to take advantage of cases
where the CFG matches the block layout, but I haven't tried.

Location lists are finalized by adding a base address selection entry,
translating each encoded block/value ID to a real PC, and adding the
terminating zero entry. This probably won't work on OSX, where dsymutil
will choke on the base address selection. I tried emitting CU-relative
relocations for each address, and it was *very* bad for performance --
it uses more memory storing all the relocations than it does for the
actual location list bytes. I think I'm going to end up synthesizing the
relocations in the linker only on OSX, but TBD.

TestNexting needs updating: with more optimizations working, the
debugger doesn't stop on the continue (line 88) any more, and the test's
duplicate suppression kicks in. Also, dx and dy live a little longer
now, but they have the correct values.

Change-Id: Ie772dfe23a4e389ca573624fac4d05401ae32307
Reviewed-on: https://go-review.googlesource.com/89356
Run-TryBot: Heschi Kreinick <heschi@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
This commit is contained in:
Heschi Kreinick 2017-10-26 15:40:17 -04:00
parent 7d7af6106f
commit 2075a9323d
11 changed files with 712 additions and 834 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
src/cmd/compile/fmt_test.go
View File

@ -572,13 +572,12 @@ var knownFormats = map[string]string{
"*cmd/compile/internal/ssa.Block %v": "",
"*cmd/compile/internal/ssa.Func %s": "",
"*cmd/compile/internal/ssa.Func %v": "",
"*cmd/compile/internal/ssa.LocalSlot %+v": "",
"*cmd/compile/internal/ssa.LocalSlot %v": "",
"*cmd/compile/internal/ssa.Register %s": "",
"*cmd/compile/internal/ssa.Register %v": "",
"*cmd/compile/internal/ssa.SparseTreeNode %v": "",
"*cmd/compile/internal/ssa.Value %s": "",
"*cmd/compile/internal/ssa.Value %v": "",
"*cmd/compile/internal/ssa.VarLoc %v": "",
"*cmd/compile/internal/ssa.sparseTreeMapEntry %v": "",
"*cmd/compile/internal/types.Field %p": "",
"*cmd/compile/internal/types.Field %v": "",
@ -597,7 +596,6 @@ var knownFormats = map[string]string{
"*cmd/compile/internal/types.Type %p": "",
"*cmd/compile/internal/types.Type %s": "",
"*cmd/compile/internal/types.Type %v": "",
"*cmd/internal/dwarf.Location %#v": "",
"*cmd/internal/obj.Addr %v": "",
"*cmd/internal/obj.LSym %v": "",
"*math/big.Int %#x": "",
@ -605,13 +603,12 @@ var knownFormats = map[string]string{
"[16]byte %x": "",
"[]*cmd/compile/internal/gc.Node %v": "",
"[]*cmd/compile/internal/gc.Sig %#v": "",
"[]*cmd/compile/internal/ssa.Block %v": "",
"[]*cmd/compile/internal/ssa.Value %v": "",
"[][]cmd/compile/internal/ssa.SlotID %v": "",
"[]byte %s": "",
"[]byte %x": "",
"[]cmd/compile/internal/ssa.Edge %v": "",
"[]cmd/compile/internal/ssa.ID %v": "",
"[]cmd/compile/internal/ssa.VarLocList %v": "",
"[]cmd/compile/internal/syntax.token %s": "",
"[]string %v": "",
"bool %v": "",
@ -637,18 +634,17 @@ var knownFormats = map[string]string{
"cmd/compile/internal/gc.Val %v": "",
"cmd/compile/internal/gc.fmtMode %d": "",
"cmd/compile/internal/gc.initKind %d": "",
"cmd/compile/internal/gc.locID %v": "",
"cmd/compile/internal/ssa.BranchPrediction %d": "",
"cmd/compile/internal/ssa.Edge %v": "",
"cmd/compile/internal/ssa.GCNode %v": "",
"cmd/compile/internal/ssa.ID %d": "",
"cmd/compile/internal/ssa.ID %v": "",
"cmd/compile/internal/ssa.LocalSlot %s": "",
"cmd/compile/internal/ssa.LocalSlot %v": "",
"cmd/compile/internal/ssa.Location %s": "",
"cmd/compile/internal/ssa.Op %s": "",
"cmd/compile/internal/ssa.Op %v": "",
"cmd/compile/internal/ssa.ValAndOff %s": "",
"cmd/compile/internal/ssa.VarLocList %v": "",
"cmd/compile/internal/ssa.rbrank %d": "",
"cmd/compile/internal/ssa.regMask %d": "",
"cmd/compile/internal/ssa.register %d": "",
@ -663,7 +659,6 @@ var knownFormats = map[string]string{
"cmd/compile/internal/types.EType %d": "",
"cmd/compile/internal/types.EType %s": "",
"cmd/compile/internal/types.EType %v": "",
"cmd/internal/dwarf.Location %#v": "",
"cmd/internal/src.Pos %s": "",
"cmd/internal/src.Pos %v": "",
"error %v": "",

299
src/cmd/compile/internal/gc/pgen.go
View File

@ -13,7 +13,6 @@ import (
"cmd/internal/src"
"cmd/internal/sys"
"fmt"
"math"
"math/rand"
"sort"
"strings"
@ -304,8 +303,6 @@ func compileFunctions() {
func debuginfo(fnsym *obj.LSym, curfn interface{}) ([]dwarf.Scope, dwarf.InlCalls) {
fn := curfn.(*Node)
debugInfo := fn.Func.DebugInfo
fn.Func.DebugInfo = nil
if fn.Func.Nname != nil {
if expect := fn.Func.Nname.Sym.Linksym(); fnsym != expect {
Fatalf("unexpected fnsym: %v != %v", fnsym, expect)
@ -344,7 +341,7 @@ func debuginfo(fnsym *obj.LSym, curfn interface{}) ([]dwarf.Scope, dwarf.InlCall
})
}
decls, dwarfVars := createDwarfVars(fnsym, debugInfo, automDecls)
decls, dwarfVars := createDwarfVars(fnsym, fn.Func, automDecls)
var varScopes []ScopeID
for _, decl := range decls {
@ -437,65 +434,24 @@ func createSimpleVars(automDecls []*Node) ([]*Node, []*dwarf.Var, map[*Node]bool
return decls, vars, selected
}
type varPart struct {
varOffset int64
slot ssa.SlotID
}
func createComplexVars(fnsym *obj.LSym, debugInfo *ssa.FuncDebug, automDecls []*Node) ([]*Node, []*dwarf.Var, map[*Node]bool) {
for _, blockDebug := range debugInfo.Blocks {
for _, locList := range blockDebug.Variables {
for _, loc := range locList.Locations {
if loc.StartProg != nil {
loc.StartPC = loc.StartProg.Pc
}
if loc.EndProg != nil {
loc.EndPC = loc.EndProg.Pc
} else {
loc.EndPC = fnsym.Size
}
if Debug_locationlist == 0 {
loc.EndProg = nil
loc.StartProg = nil
}
}
}
}
// Group SSA variables by the user variable they were decomposed from.
varParts := map[*Node][]varPart{}
ssaVars := make(map[*Node]bool)
for slotID, slot := range debugInfo.VarSlots {
for slot.SplitOf != nil {
slot = slot.SplitOf
}
n := slot.N.(*Node)
ssaVars[n] = true
varParts[n] = append(varParts[n], varPart{varOffset(slot), ssa.SlotID(slotID)})
}
// createComplexVars creates recomposed DWARF vars with location lists,
// suitable for describing optimized code.
func createComplexVars(fnsym *obj.LSym, fn *Func, automDecls []*Node) ([]*Node, []*dwarf.Var, map[*Node]bool) {
debugInfo := fn.DebugInfo
// Produce a DWARF variable entry for each user variable.
// Don't iterate over the map -- that's nondeterministic, and
// createComplexVar has side effects. Instead, go by slot.
var decls []*Node
var vars []*dwarf.Var
for _, slot := range debugInfo.VarSlots {
for slot.SplitOf != nil {
slot = slot.SplitOf
}
n := slot.N.(*Node)
parts := varParts[n]
if parts == nil {
continue
}
// Don't work on this variable again, no matter how many slots it has.
delete(varParts, n)
ssaVars := make(map[*Node]bool)
// Get the order the parts need to be in to represent the memory
// of the decomposed user variable.
sort.Sort(partsByVarOffset(parts))
for varID := range debugInfo.Vars {
n := debugInfo.Vars[varID].(*Node)
ssaVars[n] = true
for _, slot := range debugInfo.VarSlots[varID] {
ssaVars[debugInfo.Slots[slot].N.(*Node)] = true
}
if dvar := createComplexVar(debugInfo, n, parts); dvar != nil {
if dvar := createComplexVar(fn, ssa.VarID(varID)); dvar != nil {
decls = append(decls, n)
vars = append(vars, dvar)
}
@ -504,13 +460,15 @@ func createComplexVars(fnsym *obj.LSym, debugInfo *ssa.FuncDebug, automDecls []*
return decls, vars, ssaVars
}
func createDwarfVars(fnsym *obj.LSym, debugInfo *ssa.FuncDebug, automDecls []*Node) ([]*Node, []*dwarf.Var) {
// createDwarfVars process fn, returning a list of DWARF variables and the
// Nodes they represent.
func createDwarfVars(fnsym *obj.LSym, fn *Func, automDecls []*Node) ([]*Node, []*dwarf.Var) {
// Collect a raw list of DWARF vars.
var vars []*dwarf.Var
var decls []*Node
var selected map[*Node]bool
if Ctxt.Flag_locationlists && Ctxt.Flag_optimize && debugInfo != nil {
decls, vars, selected = createComplexVars(fnsym, debugInfo, automDecls)
if Ctxt.Flag_locationlists && Ctxt.Flag_optimize && fn.DebugInfo != nil {
decls, vars, selected = createComplexVars(fnsym, fn, automDecls)
} else {
decls, vars, selected = createSimpleVars(automDecls)
}
@ -635,22 +593,6 @@ func (s byNodeName) Len() int { return len(s) }
func (s byNodeName) Less(i, j int) bool { return cmpNodeName(s[i], s[j]) }
func (s byNodeName) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
// varOffset returns the offset of slot within the user variable it was
// decomposed from. This has nothing to do with its stack offset.
func varOffset(slot *ssa.LocalSlot) int64 {
offset := slot.Off
for ; slot.SplitOf != nil; slot = slot.SplitOf {
offset += slot.SplitOffset
}
return offset
}
type partsByVarOffset []varPart
func (a partsByVarOffset) Len() int { return len(a) }
func (a partsByVarOffset) Less(i, j int) bool { return a[i].varOffset < a[j].varOffset }
func (a partsByVarOffset) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
// stackOffset returns the stack location of a LocalSlot relative to the
// stack pointer, suitable for use in a DWARF location entry. This has nothing
// to do with its offset in the user variable.
@ -671,24 +613,17 @@ func stackOffset(slot *ssa.LocalSlot) int32 {
return int32(base + n.Xoffset + slot.Off)
}
// createComplexVar builds a DWARF variable entry and location list representing n.
func createComplexVar(debugInfo *ssa.FuncDebug, n *Node, parts []varPart) *dwarf.Var {
slots := debugInfo.Slots
var offs int64 // base stack offset for this kind of variable
// createComplexVar builds a single DWARF variable entry and location list.
func createComplexVar(fn *Func, varID ssa.VarID) *dwarf.Var {
debug := fn.DebugInfo
n := debug.Vars[varID].(*Node)
var abbrev int
switch n.Class() {
case PAUTO:
abbrev = dwarf.DW_ABRV_AUTO_LOCLIST
if Ctxt.FixedFrameSize() == 0 {
offs -= int64(Widthptr)
}
if objabi.Framepointer_enabled(objabi.GOOS, objabi.GOARCH) {
offs -= int64(Widthptr)
}
case PPARAM, PPARAMOUT:
abbrev = dwarf.DW_ABRV_PARAM_LOCLIST
offs += Ctxt.FixedFrameSize()
default:
return nil
}
@ -712,196 +647,20 @@ func createComplexVar(debugInfo *ssa.FuncDebug, n *Node, parts []varPart) *dwarf
Abbrev: abbrev,
Type: Ctxt.Lookup(typename),
// The stack offset is used as a sorting key, so for decomposed
// variables just give it the lowest one. It's not used otherwise.
// variables just give it the first one. It's not used otherwise.
// This won't work well if the first slot hasn't been assigned a stack
// location, but it's not obvious how to do better.
StackOffset: int32(stackOffset(slots[parts[0].slot])),
StackOffset: stackOffset(debug.Slots[debug.VarSlots[varID][0]]),
DeclFile: declpos.Base().SymFilename(),
DeclLine: declpos.Line(),
DeclCol: declpos.Col(),
InlIndex: int32(inlIndex),
ChildIndex: -1,
}
if Debug_locationlist != 0 {
Ctxt.Logf("Building location list for %+v. Parts:\n", n)
for _, part := range parts {
Ctxt.Logf("\t%v => %v\n", debugInfo.Slots[part.slot], debugInfo.SlotLocsString(part.slot))
}
}
// Given a variable that's been decomposed into multiple parts,
// its location list may need a new entry after the beginning or
// end of every location entry for each of its parts. For example:
//
// [variable] [pc range]
// string.ptr |----|-----| |----|
// string.len |------------| |--|
// ... needs a location list like:
// string |----|-----|-| |--|-|
//
// Note that location entries may or may not line up with each other,
// and some of the result will only have one or the other part.
//
// To build the resulting list:
// - keep a "current" pointer for each part
// - find the next transition point
// - advance the current pointer for each part up to that transition point
// - build the piece for the range between that transition point and the next
// - repeat
type locID struct {
block int
loc int
}
findLoc := func(part varPart, id locID) *ssa.VarLoc {
if id.block >= len(debugInfo.Blocks) {
return nil
}
return debugInfo.Blocks[id.block].Variables[part.slot].Locations[id.loc]
}
nextLoc := func(part varPart, id locID) (locID, *ssa.VarLoc) {
// Check if there's another loc in this block
id.loc++
if b := debugInfo.Blocks[id.block]; b != nil && id.loc < len(b.Variables[part.slot].Locations) {
return id, findLoc(part, id)
}
// Find the next block that has a loc for this part.
id.loc = 0
id.block++
for ; id.block < len(debugInfo.Blocks); id.block++ {
if b := debugInfo.Blocks[id.block]; b != nil && len(b.Variables[part.slot].Locations) != 0 {
return id, findLoc(part, id)
}
}
return id, nil
}
curLoc := make([]locID, len(slots))
// Position each pointer at the first entry for its slot.
for _, part := range parts {
if b := debugInfo.Blocks[0]; b != nil && len(b.Variables[part.slot].Locations) != 0 {
// Block 0 has an entry; no need to advance.
continue
}
curLoc[part.slot], _ = nextLoc(part, curLoc[part.slot])
}
// findBoundaryAfter finds the next beginning or end of a piece after currentPC.
findBoundaryAfter := func(currentPC int64) int64 {
min := int64(math.MaxInt64)
for _, part := range parts {
// For each part, find the first PC greater than current. Doesn't
// matter if it's a start or an end, since we're looking for any boundary.
// If it's the new winner, save it.
onePart:
for i, loc := curLoc[part.slot], findLoc(part, curLoc[part.slot]); loc != nil; i, loc = nextLoc(part, i) {
for _, pc := range [2]int64{loc.StartPC, loc.EndPC} {
if pc > currentPC {
if pc < min {
min = pc
}
break onePart
}
}
}
}
return min
}
var start int64
end := findBoundaryAfter(0)
for {
// Advance to the next chunk.
start = end
end = findBoundaryAfter(start)
if end == math.MaxInt64 {
break
}
dloc := dwarf.Location{StartPC: start, EndPC: end}
if Debug_locationlist != 0 {
Ctxt.Logf("Processing range %x -> %x\n", start, end)
}
// Advance curLoc to the last location that starts before/at start.
// After this loop, if there's a location that covers [start, end), it will be current.
// Otherwise the current piece will be too early.
for _, part := range parts {
choice := locID{-1, -1}
for i, loc := curLoc[part.slot], findLoc(part, curLoc[part.slot]); loc != nil; i, loc = nextLoc(part, i) {
if loc.StartPC > start {
break //overshot
}
choice = i // best yet
}
if choice.block != -1 {
curLoc[part.slot] = choice
}
if Debug_locationlist != 0 {
Ctxt.Logf("\t %v => %v", slots[part.slot], curLoc[part.slot])
}
}
if Debug_locationlist != 0 {
Ctxt.Logf("\n")
}
// Assemble the location list entry for this chunk.
present := 0
for _, part := range parts {
dpiece := dwarf.Piece{
Length: slots[part.slot].Type.Size(),
}
loc := findLoc(part, curLoc[part.slot])
if loc == nil || start >= loc.EndPC || end <= loc.StartPC {
if Debug_locationlist != 0 {
Ctxt.Logf("\t%v: missing", slots[part.slot])
}
dpiece.Missing = true
dloc.Pieces = append(dloc.Pieces, dpiece)
continue
}
present++
if Debug_locationlist != 0 {
Ctxt.Logf("\t%v: %v", slots[part.slot], debugInfo.Blocks[curLoc[part.slot].block].LocString(loc))
}
if loc.OnStack {
dpiece.OnStack = true
dpiece.StackOffset = stackOffset(slots[loc.StackLocation])
} else {
for reg := 0; reg < len(debugInfo.Registers); reg++ {
if loc.Registers&(1<<uint8(reg)) != 0 {
dpiece.RegNum = Ctxt.Arch.DWARFRegisters[debugInfo.Registers[reg].ObjNum()]
}
}
}
dloc.Pieces = append(dloc.Pieces, dpiece)
}
if present == 0 {
if Debug_locationlist != 0 {
Ctxt.Logf(" -> totally missing\n")
}
continue
}
// Extend the previous entry if possible.
if len(dvar.LocationList) > 0 {
prev := &dvar.LocationList[len(dvar.LocationList)-1]
if prev.EndPC == dloc.StartPC && len(prev.Pieces) == len(dloc.Pieces) {
equal := true
for i := range prev.Pieces {
if prev.Pieces[i] != dloc.Pieces[i] {
equal = false
}
}
if equal {
prev.EndPC = end
if Debug_locationlist != 0 {
Ctxt.Logf("-> merged with previous, now %#v\n", prev)
}
continue
}
}
}
dvar.LocationList = append(dvar.LocationList, dloc)
if Debug_locationlist != 0 {
Ctxt.Logf("-> added: %#v\n", dloc)
list := debug.LocationLists[varID]
if len(list) != 0 {
dvar.PutLocationList = func(listSym, startPC dwarf.Sym) {
debug.PutLocationList(list, Ctxt, listSym.(*obj.LSym), startPC.(*obj.LSym))
}
}
return dvar

55
src/cmd/compile/internal/gc/ssa.go
View File

@ -4652,15 +4652,14 @@ func genssa(f *ssa.Func, pp *Progs) {
s.ScratchFpMem = e.scratchFpMem
logLocationLists := Debug_locationlist != 0
if Ctxt.Flag_locationlists {
e.curfn.Func.DebugInfo = ssa.BuildFuncDebug(f, logLocationLists)
valueToProgAfter = make([]*obj.Prog, f.NumValues())
}
// Emit basic blocks
for i, b := range f.Blocks {
s.bstart[b.ID] = s.pp.next
// Emit values in block
thearch.SSAMarkMoves(&s, b)
for _, v := range b.Values {
@ -4698,8 +4697,6 @@ func genssa(f *ssa.Func, pp *Progs) {
}
case ssa.OpPhi:
CheckLoweredPhi(v)
case ssa.OpRegKill:
// nothing to do
default:
// let the backend handle it
thearch.SSAGenValue(&s, v)
@ -4708,12 +4705,14 @@ func genssa(f *ssa.Func, pp *Progs) {
if Ctxt.Flag_locationlists {
valueToProgAfter[v.ID] = s.pp.next
}
if logProgs {
for ; x != s.pp.next; x = x.Link {
progToValue[x] = v
}
}
}
// Emit control flow instructions for block
var next *ssa.Block
if i < len(f.Blocks)-1 && Debug['N'] == 0 {
@ -4734,41 +4733,19 @@ func genssa(f *ssa.Func, pp *Progs) {
}
if Ctxt.Flag_locationlists {
for i := range f.Blocks {
blockDebug := e.curfn.Func.DebugInfo.Blocks[i]
for _, locList := range blockDebug.Variables {
for _, loc := range locList.Locations {
if loc.Start == ssa.BlockStart {
loc.StartProg = s.bstart[f.Blocks[i].ID]
} else {
loc.StartProg = valueToProgAfter[loc.Start.ID]
}
if loc.End == nil {
Fatalf("empty loc %v compiling %v", loc, f.Name)
}
if loc.End == ssa.BlockEnd {
// If this variable was live at the end of the block, it should be
// live over the control flow instructions. Extend it up to the
// beginning of the next block.
// If this is the last block, then there's no Prog to use for it, and
// EndProg is unset.
if i < len(f.Blocks)-1 {
loc.EndProg = s.bstart[f.Blocks[i+1].ID]
}
} else {
// Advance the "end" forward by one; the end-of-range doesn't take effect
// until the instruction actually executes.
loc.EndProg = valueToProgAfter[loc.End.ID].Link
if loc.EndProg == nil {
Fatalf("nil loc.EndProg compiling %v, loc=%v", f.Name, loc)
}
}
if !logLocationLists {
loc.Start = nil
loc.End = nil
}
}
e.curfn.Func.DebugInfo = ssa.BuildFuncDebug(Ctxt, f, Debug_locationlist > 1, stackOffset)
bstart := s.bstart
// Note that at this moment, Prog.Pc is a sequence number; it's
// not a real PC until after assembly, so this mapping has to
// be done later.
e.curfn.Func.DebugInfo.GetPC = func(b, v ssa.ID) int64 {
switch v {
case ssa.BlockStart.ID:
return int64(bstart[b].Pc)
case ssa.BlockEnd.ID:
return int64(e.curfn.Func.lsym.Size)
default:
return int64(valueToProgAfter[v].Pc)
}
}
}

22
src/cmd/compile/internal/ssa/cache.go
View File

@ -14,11 +14,6 @@ type Cache struct {
blocks [200]Block
locs [2000]Location
// Storage for DWARF variable locations. Lazily allocated
// since location lists are off by default.
varLocs []VarLoc
curVarLoc int
// Reusable stackAllocState.
// See stackalloc.go's {new,put}StackAllocState.
stackAllocState *stackAllocState
@ -43,21 +38,4 @@ func (c *Cache) Reset() {
for i := range xl {
xl[i] = nil
}
xvl := c.varLocs[:c.curVarLoc]
for i := range xvl {
xvl[i] = VarLoc{}
}
c.curVarLoc = 0
}
func (c *Cache) NewVarLoc() *VarLoc {
if c.varLocs == nil {
c.varLocs = make([]VarLoc, 4000)
}
if c.curVarLoc == len(c.varLocs) {
return &VarLoc{}
}
vl := &c.varLocs[c.curVarLoc]
c.curVarLoc++
return vl
}

4
src/cmd/compile/internal/ssa/check.go
View File

@ -465,10 +465,6 @@ func memCheck(f *Func) {
if seenNonPhi {
f.Fatalf("phi after non-phi @ %s: %s", b, v)
}
case OpRegKill:
if f.RegAlloc == nil {
f.Fatalf("RegKill seen before register allocation @ %s: %s", b, v)
}
default:
seenNonPhi = true
}

988
src/cmd/compile/internal/ssa/debug.go
View File

File diff suppressed because it is too large Load Diff

1
src/cmd/compile/internal/ssa/gen/genericOps.go
View File

@ -450,7 +450,6 @@ var genericOps = []opData{
{name: "VarKill", argLength: 1, aux: "Sym", symEffect: "None"}, // aux is a *gc.Node of a variable that is known to be dead. arg0=mem, returns mem
{name: "VarLive", argLength: 1, aux: "Sym", symEffect: "Read"}, // aux is a *gc.Node of a variable that must be kept live. arg0=mem, returns mem
{name: "KeepAlive", argLength: 2, typ: "Mem"}, // arg[0] is a value that must be kept alive until this mark. arg[1]=mem, returns mem
{name: "RegKill"}, // regalloc has determined that the value in this register is dead
// Ops for breaking 64-bit operations on 32-bit architectures
{name: "Int64Make", argLength: 2, typ: "UInt64"}, // arg0=hi, arg1=lo

6
src/cmd/compile/internal/ssa/opGen.go
View File

@ -2017,7 +2017,6 @@ const (
OpVarKill
OpVarLive
OpKeepAlive
OpRegKill
OpInt64Make
OpInt64Hi
OpInt64Lo
@ -24081,11 +24080,6 @@ var opcodeTable = [...]opInfo{
argLen: 2,
generic: true,
},
{
name: "RegKill",
argLen: 0,
generic: true,
},
{
name: "Int64Make",
argLen: 2,

55
src/cmd/compile/internal/ssa/regalloc.go
View File

@ -242,9 +242,6 @@ type regAllocState struct {
// current state of each (preregalloc) Value
values []valState
// names associated with each Value
valueNames [][]LocalSlot
// ID of SP, SB values
sp, sb ID
@ -303,13 +300,6 @@ type startReg struct {
// freeReg frees up register r. Any current user of r is kicked out.
func (s *regAllocState) freeReg(r register) {
s.freeOrResetReg(r, false)
}
// freeOrResetReg frees up register r. Any current user of r is kicked out.
// resetting indicates that the operation is only for bookkeeping,
// e.g. when clearing out state upon entry to a new block.
func (s *regAllocState) freeOrResetReg(r register, resetting bool) {
v := s.regs[r].v
if v == nil {
s.f.Fatalf("tried to free an already free register %d\n", r)
@ -319,16 +309,6 @@ func (s *regAllocState) freeOrResetReg(r register, resetting bool) {
if s.f.pass.debug > regDebug {
fmt.Printf("freeReg %s (dump %s/%s)\n", &s.registers[r], v, s.regs[r].c)
}
if !resetting && s.f.Config.ctxt.Flag_locationlists && len(s.valueNames[v.ID]) != 0 {
kill := s.curBlock.NewValue0(src.NoXPos, OpRegKill, types.TypeVoid)
for int(kill.ID) >= len(s.orig) {
s.orig = append(s.orig, nil)
}
for _, name := range s.valueNames[v.ID] {
s.f.NamedValues[name] = append(s.f.NamedValues[name], kill)
}
s.f.setHome(kill, &s.registers[r])
}
s.regs[r] = regState{}
s.values[v.ID].regs &^= regMask(1) << r
s.used &^= regMask(1) << r
@ -613,17 +593,6 @@ func (s *regAllocState) init(f *Func) {
s.values = make([]valState, f.NumValues())
s.orig = make([]*Value, f.NumValues())
s.copies = make(map[*Value]bool)
if s.f.Config.ctxt.Flag_locationlists {
s.valueNames = make([][]LocalSlot, f.NumValues())
for slot, values := range f.NamedValues {
if isSynthetic(&slot) {
continue
}
for _, value := range values {
s.valueNames[value.ID] = append(s.valueNames[value.ID], slot)
}
}
}
for _, b := range f.Blocks {
for _, v := range b.Values {
if !v.Type.IsMemory() && !v.Type.IsVoid() && !v.Type.IsFlags() && !v.Type.IsTuple() {
@ -717,9 +686,7 @@ func (s *regAllocState) liveAfterCurrentInstruction(v *Value) bool {
// Sets the state of the registers to that encoded in regs.
func (s *regAllocState) setState(regs []endReg) {
for s.used != 0 {
s.freeOrResetReg(pickReg(s.used), true)
}
s.freeRegs(s.used)
for _, x := range regs {
s.assignReg(x.r, x.v, x.c)
}
@ -1035,7 +1002,7 @@ func (s *regAllocState) regalloc(f *Func) {
pidx := e.i
for _, v := range succ.Values {
if v.Op != OpPhi {
continue
break
}
if !s.values[v.ID].needReg {
continue
@ -1598,9 +1565,6 @@ func (s *regAllocState) placeSpills() {
for _, b := range f.Blocks {
var m regMask
for _, v := range b.Values {
if v.Op == OpRegKill {
continue
}
if v.Op != OpPhi {
break
}
@ -1711,7 +1675,7 @@ func (s *regAllocState) placeSpills() {
for _, b := range f.Blocks {
nphi := 0
for _, v := range b.Values {
if v.Op != OpRegKill && v.Op != OpPhi {
if v.Op != OpPhi {
break
}
nphi++
@ -1832,9 +1796,6 @@ func (e *edgeState) setup(idx int, srcReg []endReg, dstReg []startReg, stacklive
}
// Phis need their args to end up in a specific location.
for _, v := range e.b.Values {
if v.Op == OpRegKill {
continue
}
if v.Op != OpPhi {
break
}
@ -2094,16 +2055,6 @@ func (e *edgeState) erase(loc Location) {
fmt.Printf("v%d no longer available in %s:%s\n", vid, loc, c)
}
a[i], a = a[len(a)-1], a[:len(a)-1]
if e.s.f.Config.ctxt.Flag_locationlists {
if _, isReg := loc.(*Register); isReg && int(c.ID) < len(e.s.valueNames) && len(e.s.valueNames[c.ID]) != 0 {
kill := e.p.NewValue0(src.NoXPos, OpRegKill, types.TypeVoid)
e.s.f.setHome(kill, loc)
for _, name := range e.s.valueNames[c.ID] {
e.s.f.NamedValues[name] = append(e.s.f.NamedValues[name], kill)
}
}
}
break
}
}

13
src/cmd/compile/internal/ssa/testdata/hist.gdb-opt.nexts vendored
View File

@ -14,7 +14,7 @@ dy = <Optimized out, as expected>
dx = 2
dy = 2
63: hist := make([]int, 7) //gdb-opt=(dx/O,dy/O) // TODO sink is missing if this code is in 'test' instead of 'main'
dx = <Optimized out, as expected>
dx = 2
dy = <Optimized out, as expected>
64: var reader io.Reader = strings.NewReader(cannedInput) //gdb-dbg=(hist/A) // TODO cannedInput/A is missing if this code is in 'test' instead of 'main'
65: if len(os.Args) > 1 {
@ -116,11 +116,6 @@ scanner = (struct bufio.Scanner *) <A>
a = 0
n = 0
t = 0
88: continue
87: if a == 0 { //gdb-opt=(a,n,t)
a = 3
n = 0
t = 0
92: fmt.Fprintf(os.Stderr, "%d\t%d\t%d\t%d\t%d\n", i, a, n, i*a, t) //gdb-dbg=(n,i,t)
91: n += a
92: fmt.Fprintf(os.Stderr, "%d\t%d\t%d\t%d\t%d\n", i, a, n, i*a, t) //gdb-dbg=(n,i,t)
@ -147,11 +142,6 @@ t = 3
a = 0
n = 6
t = 9
88: continue
87: if a == 0 { //gdb-opt=(a,n,t)
a = 2
n = 6
t = 9
92: fmt.Fprintf(os.Stderr, "%d\t%d\t%d\t%d\t%d\n", i, a, n, i*a, t) //gdb-dbg=(n,i,t)
91: n += a
92: fmt.Fprintf(os.Stderr, "%d\t%d\t%d\t%d\t%d\n", i, a, n, i*a, t) //gdb-dbg=(n,i,t)
@ -178,5 +168,4 @@ t = 17
a = 0
n = 9
t = 22
88: continue
98: }

66
src/cmd/internal/dwarf/dwarf.go
View File

@ -44,23 +44,6 @@ type Sym interface {
Len() int64
}
// A Location represents a variable's location at a particular PC range.
// It becomes a location list entry in the DWARF.
type Location struct {
StartPC, EndPC int64
Pieces []Piece
}
// A Piece represents the location of a particular part of a variable.
// It becomes part of a location list entry (a DW_OP_piece) in the DWARF.
type Piece struct {
Length int64
StackOffset int32
RegNum int16
Missing bool
OnStack bool // if true, RegNum is unset.
}
// A Var represents a local variable or a function parameter.
type Var struct {
Name string
@ -68,7 +51,9 @@ type Var struct {
IsReturnValue bool
IsInlFormal bool
StackOffset int32
LocationList []Location
// This package can't use the ssa package, so it can't mention ssa.FuncDebug,
// so indirect through a closure.
PutLocationList func(listSym, startPC Sym)
Scope int32
Type Sym
DeclFile string
@ -1360,10 +1345,10 @@ func determineVarAbbrev(v *Var, fnabbrev int) (int, bool, bool) {
// convert to an inline abbreviation and emit an empty location.
missing := false
switch {
case abbrev == DW_ABRV_AUTO_LOCLIST && len(v.LocationList) == 0:
case abbrev == DW_ABRV_AUTO_LOCLIST && v.PutLocationList == nil:
missing = true
abbrev = DW_ABRV_AUTO
case abbrev == DW_ABRV_PARAM_LOCLIST && len(v.LocationList) == 0:
case abbrev == DW_ABRV_PARAM_LOCLIST && v.PutLocationList == nil:
missing = true
abbrev = DW_ABRV_PARAM
}
@ -1470,7 +1455,7 @@ func putvar(ctxt Context, s *FnState, v *Var, absfn Sym, fnabbrev, inlIndex int,
if abbrevUsesLoclist(abbrev) {
putattr(ctxt, s.Info, abbrev, DW_FORM_sec_offset, DW_CLS_PTR, int64(s.Loc.Len()), s.Loc)
addLocList(ctxt, s.Loc, s.StartPC, v, encbuf)
v.PutLocationList(s.Loc, s.StartPC)
} else {
loc := encbuf[:0]
switch {
@ -1488,45 +1473,6 @@ func putvar(ctxt Context, s *FnState, v *Var, absfn Sym, fnabbrev, inlIndex int,
// Var has no children => no terminator
}
func addLocList(ctxt Context, listSym, startPC Sym, v *Var, encbuf []byte) {
// Base address entry: max ptr followed by the base address.
ctxt.AddInt(listSym, ctxt.PtrSize(), ^0)
ctxt.AddAddress(listSym, startPC, 0)
for _, entry := range v.LocationList {
ctxt.AddInt(listSym, ctxt.PtrSize(), entry.StartPC)
ctxt.AddInt(listSym, ctxt.PtrSize(), entry.EndPC)
locBuf := encbuf[:0]
for _, piece := range entry.Pieces {
if !piece.Missing {
if piece.OnStack {
if piece.StackOffset == 0 {
locBuf = append(locBuf, DW_OP_call_frame_cfa)
} else {
locBuf = append(locBuf, DW_OP_fbreg)
locBuf = AppendSleb128(locBuf, int64(piece.StackOffset))
}
} else {
if piece.RegNum < 32 {
locBuf = append(locBuf, DW_OP_reg0+byte(piece.RegNum))
} else {
locBuf = append(locBuf, DW_OP_regx)
locBuf = AppendUleb128(locBuf, uint64(piece.RegNum))
}
}
}
if len(entry.Pieces) > 1 {
locBuf = append(locBuf, DW_OP_piece)
locBuf = AppendUleb128(locBuf, uint64(piece.Length))
}
}
ctxt.AddInt(listSym, 2, int64(len(locBuf)))
ctxt.AddBytes(listSym, locBuf)
}
// End list
ctxt.AddInt(listSym, ctxt.PtrSize(), 0)
ctxt.AddInt(listSym, ctxt.PtrSize(), 0)
}
// VarsByOffset attaches the methods of sort.Interface to []*Var,
// sorting in increasing StackOffset.
type VarsByOffset []*Var