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cmd/compile: preserve/translate names for parameters

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This is part of getting debugging into good shape
with the register ABI.  (This may generate a backport
for 1.16, there was some regression there as well.)

This is not necessarily fully-baked yet; my goal is to
make it work "well enough" for actual debugging, then
revisit the metrics, which are currently ignorant
of registers used for passing parameters (currently,
rejects them as a valid option).

Updates #40724.

Change-Id: Ib649adf39f947b7b54895c5bf181cf48ca4d38a0
Reviewed-on: https://go-review.googlesource.com/c/go/+/311689
Trust: David Chase <drchase@google.com>
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This commit is contained in:
David Chase 2021-04-19 23:00:24 -04:00
parent 830e63a7a3
commit 0921211403
1 changed files with 126 additions and 27 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

153
src/cmd/compile/internal/ssa/expand_calls.go
View file

@ -575,6 +575,77 @@ func (x *expandState) rewriteDereference(b *Block, base, a, mem *Value, offset,
return mem
}
var indexNames [1]string = [1]string{"[0]"}
// pathTo returns the selection path to the leaf type at offset within container.
// e.g. len(thing.field[0]) => ".field[0].len"
// this is for purposes of generating names ultimately fed to a debugger.
func (x *expandState) pathTo(container, leaf *types.Type, offset int64) string {
if container == leaf || offset == 0 && container.Size() == leaf.Size() {
return ""
}
path := ""
outer:
for {
switch container.Kind() {
case types.TARRAY:
container = container.Elem()
if container.Size() == 0 {
return path
}
i := offset / container.Size()
offset = offset % container.Size()
// If a future compiler/ABI supports larger SSA/Arg-able arrays, expand indexNames.
path = path + indexNames[i]
continue
case types.TSTRUCT:
for i := 0; i < container.NumFields(); i++ {
fld := container.Field(i)
if fld.Offset+fld.Type.Size() > offset {
offset -= fld.Offset
path += "." + fld.Sym.Name
container = fld.Type
continue outer
}
}
return path
case types.TINT64, types.TUINT64:
if container.Width == x.regSize {
return path
}
if offset == x.hiOffset {
return path + ".hi"
}
return path + ".lo"
case types.TINTER:
if offset != 0 {
return path + ".data"
}
if container.IsEmptyInterface() {
return path + ".type"
}
return path + ".itab"
case types.TSLICE:
if offset == 2*x.regSize {
return path + ".cap"
}
fallthrough
case types.TSTRING:
if offset == 0 {
return path + ".ptr"
}
return path + ".len"
case types.TCOMPLEX64, types.TCOMPLEX128:
if offset == 0 {
return path + ".real"
}
return path + ".imag"
}
return path
}
}
// decomposeArg is a helper for storeArgOrLoad.
// It decomposes a Load or an Arg into smaller parts and returns the new mem.
// If the type does not match one of the expected aggregate types, it returns nil instead.
@ -591,6 +662,11 @@ func (x *expandState) rewriteDereference(b *Block, base, a, mem *Value, offset,
func (x *expandState) decomposeArg(pos src.XPos, b *Block, source, mem *Value, t *types.Type, storeOffset int64, loadRegOffset Abi1RO, storeRc registerCursor) *Value {
pa := x.prAssignForArg(source)
var locs []LocalSlot
for _, s := range x.namedSelects[source] {
locs = append(locs, x.f.Names[s.locIndex])
}
if len(pa.Registers) > 0 {
// Handle the in-registers case directly
rts, offs := pa.RegisterTypesAndOffsets()
@ -604,12 +680,21 @@ func (x *expandState) decomposeArg(pos src.XPos, b *Block, source, mem *Value, t
}
panic(fmt.Errorf("offset %d of requested register %d should be zero, source=%s", offs[loadRegOffset], loadRegOffset, source.LongString()))
}
if x.debug {
x.Printf("decompose arg %s has %d locs\n", source.LongString(), len(locs))
}
for i := loadRegOffset; i < last; i++ {
rt := rts[i]
off := offs[i]
w := x.commonArgs[selKey{source, off, rt.Width, rt}]
if w == nil {
w = x.newArgToMemOrRegs(source, w, off, i, rt, pos)
suffix := x.pathTo(source.Type, rt, off)
if suffix != "" {
x.splitSlotsIntoNames(locs, suffix, off, rt, w)
}
}
if t.IsPtrShaped() {
// Preserve the original store type. This ensures pointer type
@ -631,7 +716,7 @@ func (x *expandState) decomposeArg(pos src.XPos, b *Block, source, mem *Value, t
elemRO := x.regWidth(elem)
for i := int64(0); i < u.NumElem(); i++ {
elemOff := i * elem.Size()
mem = storeOneArg(x, pos, b, source, mem, elem, elemOff, storeOffset+elemOff, loadRegOffset, storeRc.next(elem))
mem = storeOneArg(x, pos, b, locs, indexNames[i], source, mem, elem, elemOff, storeOffset+elemOff, loadRegOffset, storeRc.next(elem))
loadRegOffset += elemRO
pos = pos.WithNotStmt()
}
@ -639,7 +724,7 @@ func (x *expandState) decomposeArg(pos src.XPos, b *Block, source, mem *Value, t
case types.TSTRUCT:
for i := 0; i < u.NumFields(); i++ {
fld := u.Field(i)
mem = storeOneArg(x, pos, b, source, mem, fld.Type, fld.Offset, storeOffset+fld.Offset, loadRegOffset, storeRc.next(fld.Type))
mem = storeOneArg(x, pos, b, locs, "."+fld.Sym.Name, source, mem, fld.Type, fld.Offset, storeOffset+fld.Offset, loadRegOffset, storeRc.next(fld.Type))
loadRegOffset += x.regWidth(fld.Type)
pos = pos.WithNotStmt()
}
@ -649,24 +734,36 @@ func (x *expandState) decomposeArg(pos src.XPos, b *Block, source, mem *Value, t
break
}
tHi, tLo := x.intPairTypes(t.Kind())
mem = storeOneArg(x, pos, b, source, mem, tHi, x.hiOffset, storeOffset+x.hiOffset, loadRegOffset+x.hiRo, storeRc.plus(x.hiRo))
mem = storeOneArg(x, pos, b, locs, ".hi", source, mem, tHi, x.hiOffset, storeOffset+x.hiOffset, loadRegOffset+x.hiRo, storeRc.plus(x.hiRo))
pos = pos.WithNotStmt()
return storeOneArg(x, pos, b, source, mem, tLo, x.lowOffset, storeOffset+x.lowOffset, loadRegOffset+x.loRo, storeRc.plus(x.loRo))
return storeOneArg(x, pos, b, locs, ".lo", source, mem, tLo, x.lowOffset, storeOffset+x.lowOffset, loadRegOffset+x.loRo, storeRc.plus(x.loRo))
case types.TINTER:
return storeTwoArg(x, pos, b, source, mem, x.typs.Uintptr, x.typs.BytePtr, 0, storeOffset, loadRegOffset, storeRc)
sfx := ".itab"
if u.IsEmptyInterface() {
sfx = ".type"
}
return storeTwoArg(x, pos, b, locs, sfx, ".idata", source, mem, x.typs.Uintptr, x.typs.BytePtr, 0, storeOffset, loadRegOffset, storeRc)
case types.TSTRING:
return storeTwoArg(x, pos, b, source, mem, x.typs.BytePtr, x.typs.Int, 0, storeOffset, loadRegOffset, storeRc)
return storeTwoArg(x, pos, b, locs, ".ptr", ".len", source, mem, x.typs.BytePtr, x.typs.Int, 0, storeOffset, loadRegOffset, storeRc)
case types.TCOMPLEX64:
return storeTwoArg(x, pos, b, source, mem, x.typs.Float32, x.typs.Float32, 0, storeOffset, loadRegOffset, storeRc)
return storeTwoArg(x, pos, b, locs, ".real", ".imag", source, mem, x.typs.Float32, x.typs.Float32, 0, storeOffset, loadRegOffset, storeRc)
case types.TCOMPLEX128:
return storeTwoArg(x, pos, b, source, mem, x.typs.Float64, x.typs.Float64, 0, storeOffset, loadRegOffset, storeRc)
return storeTwoArg(x, pos, b, locs, ".real", ".imag", source, mem, x.typs.Float64, x.typs.Float64, 0, storeOffset, loadRegOffset, storeRc)
case types.TSLICE:
mem = storeOneArg(x, pos, b, source, mem, x.typs.BytePtr, 0, storeOffset, loadRegOffset, storeRc.next(x.typs.BytePtr))
return storeTwoArg(x, pos, b, source, mem, x.typs.Int, x.typs.Int, x.ptrSize, storeOffset+x.ptrSize, loadRegOffset+RO_slice_len, storeRc)
mem = storeOneArg(x, pos, b, locs, ".ptr", source, mem, x.typs.BytePtr, 0, storeOffset, loadRegOffset, storeRc.next(x.typs.BytePtr))
return storeTwoArg(x, pos, b, locs, ".len", ".cap", source, mem, x.typs.Int, x.typs.Int, x.ptrSize, storeOffset+x.ptrSize, loadRegOffset+RO_slice_len, storeRc)
}
return nil
}
func (x *expandState) splitSlotsIntoNames(locs []LocalSlot, suffix string, off int64, rt *types.Type, w *Value) {
wlocs := x.splitSlots(locs, suffix, off, rt)
for _, l := range wlocs {
x.f.NamedValues[l] = append(x.f.NamedValues[l], w)
}
x.f.Names = append(x.f.Names, wlocs...)
}
// decomposeLoad is a helper for storeArgOrLoad.
// It decomposes a Load into smaller parts and returns the new mem.
// If the type does not match one of the expected aggregate types, it returns nil instead.
@ -729,7 +826,7 @@ func (x *expandState) decomposeLoad(pos src.XPos, b *Block, source, mem *Value,
// storeOneArg creates a decomposed (one step) arg that is then stored.
// pos and b locate the store instruction, source is the "base" of the value input,
// mem is the input mem, t is the type in question, and offArg and offStore are the offsets from the respective bases.
func storeOneArg(x *expandState, pos src.XPos, b *Block, source, mem *Value, t *types.Type, argOffset, storeOffset int64, loadRegOffset Abi1RO, storeRc registerCursor) *Value {
func storeOneArg(x *expandState, pos src.XPos, b *Block, locs []LocalSlot, suffix string, source, mem *Value, t *types.Type, argOffset, storeOffset int64, loadRegOffset Abi1RO, storeRc registerCursor) *Value {
if x.debug {
x.indent(3)
defer x.indent(-3)
@ -739,6 +836,7 @@ func storeOneArg(x *expandState, pos src.XPos, b *Block, source, mem *Value, t *
w := x.commonArgs[selKey{source, argOffset, t.Width, t}]
if w == nil {
w = x.newArgToMemOrRegs(source, w, argOffset, loadRegOffset, t, pos)
x.splitSlotsIntoNames(locs, suffix, argOffset, t, w)
}
return x.storeArgOrLoad(pos, b, w, mem, t, storeOffset, loadRegOffset, storeRc)
}
@ -750,11 +848,11 @@ func storeOneLoad(x *expandState, pos src.XPos, b *Block, source, mem *Value, t
return x.storeArgOrLoad(pos, b, w, mem, t, offStore, loadRegOffset, storeRc)
}
func storeTwoArg(x *expandState, pos src.XPos, b *Block, source, mem *Value, t1, t2 *types.Type, offArg, offStore int64, loadRegOffset Abi1RO, storeRc registerCursor) *Value {
mem = storeOneArg(x, pos, b, source, mem, t1, offArg, offStore, loadRegOffset, storeRc.next(t1))
func storeTwoArg(x *expandState, pos src.XPos, b *Block, locs []LocalSlot, suffix1 string, suffix2 string, source, mem *Value, t1, t2 *types.Type, offArg, offStore int64, loadRegOffset Abi1RO, storeRc registerCursor) *Value {
mem = storeOneArg(x, pos, b, locs, suffix1, source, mem, t1, offArg, offStore, loadRegOffset, storeRc.next(t1))
pos = pos.WithNotStmt()
t1Size := t1.Size()
return storeOneArg(x, pos, b, source, mem, t2, offArg+t1Size, offStore+t1Size, loadRegOffset+1, storeRc)
return storeOneArg(x, pos, b, locs, suffix2, source, mem, t2, offArg+t1Size, offStore+t1Size, loadRegOffset+1, storeRc)
}
// storeTwoLoad creates a pair of decomposed (one step) loads that are then stored.
@ -1067,6 +1165,18 @@ func expandCalls(f *Func) {
x.Printf("\nexpandsCalls(%s)\n", f.Name)
}
for i, name := range f.Names {
t := name.Type
if x.isAlreadyExpandedAggregateType(t) {
for j, v := range f.NamedValues[name] {
if v.Op == OpSelectN || v.Op == OpArg && x.isAlreadyExpandedAggregateType(v.Type) {
ns := x.namedSelects[v]
x.namedSelects[v] = append(ns, namedVal{locIndex: i, valIndex: j})
}
}
}
}
// TODO if too slow, whole program iteration can be replaced w/ slices of appropriate values, accumulated in first loop here.
// Step 0: rewrite the calls to convert args to calls into stores/register movement.
@ -1151,18 +1261,6 @@ func expandCalls(f *Func) {
}
}
for i, name := range f.Names {
t := name.Type
if x.isAlreadyExpandedAggregateType(t) {
for j, v := range f.NamedValues[name] {
if v.Op == OpSelectN || v.Op == OpArg && x.isAlreadyExpandedAggregateType(v.Type) {
ns := x.namedSelects[v]
x.namedSelects[v] = append(ns, namedVal{locIndex: i, valIndex: j})
}
}
}
}
// Step 1: any stores of aggregates remaining are believed to be sourced from call results or args.
// Decompose those stores into a series of smaller stores, adding selection ops as necessary.
for _, b := range f.Blocks {
@ -1386,8 +1484,9 @@ func expandCalls(f *Func) {
}
continue
}
// Not-leaf types that had debug locations need to lose them.
if ns, ok := x.namedSelects[v]; ok {
// Not-leaf types that had debug locations need to lose them.
toDelete = append(toDelete, ns...)
}
}