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cmd/compile: handle aggregate OpArg in registers 

Also handles case where OpArg does not escape but has its address
taken.

May have exposed a lurking bug in 1.16 expandCalls,
if e.g., loading len(someArrayOfstructThing[0].secondStringField)
from a local.  Maybe.

For #40724.

Change-Id: I0298c4ad5d652b5e3d7ed6a62095d59e2d8819c7
Reviewed-on: https://go-review.googlesource.com/c/go/+/293396
Trust: David Chase <drchase@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This commit is contained in:
David Chase 2021-02-17 10:38:03 -05:00
parent c4e3f6c4c7
commit 9f33dc3ca1
7 changed files with 225 additions and 93 deletions
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2
src/cmd/compile/internal/amd64/ssa.go
View File

@ -980,8 +980,6 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
ssagen.AddAux(&p.From, v)
p.To.Type = obj.TYPE_REG
p.To.Reg = v.Reg()
case ssa.OpArgIntReg, ssa.OpArgFloatReg:
ssagen.CheckArgReg(v)
case ssa.OpAMD64LoweredGetClosurePtr:
// Closure pointer is DX.
ssagen.CheckLoweredGetClosurePtr(v)

250
src/cmd/compile/internal/ssa/expand_calls.go
View File

@ -158,23 +158,24 @@ func (c *registerCursor) hasRegs() bool {
}
type expandState struct {
f *Func
abi1 *abi.ABIConfig
debug bool
canSSAType func(*types.Type) bool
regSize int64
sp *Value
typs *Types
ptrSize int64
hiOffset int64
lowOffset int64
hiRo Abi1RO
loRo Abi1RO
namedSelects map[*Value][]namedVal
sdom SparseTree
common map[selKey]*Value
offsets map[offsetKey]*Value
memForCall map[ID]*Value // For a call, need to know the unique selector that gets the mem.
f *Func
abi1 *abi.ABIConfig
debug bool
canSSAType func(*types.Type) bool
regSize int64
sp *Value
typs *Types
ptrSize int64
hiOffset int64
lowOffset int64
hiRo Abi1RO
loRo Abi1RO
namedSelects map[*Value][]namedVal
sdom SparseTree
commonSelectors map[selKey]*Value // used to de-dupe selectors
commonArgs map[selKey]*Value // used to de-dupe OpArg/OpArgIntReg/OpArgFloatReg
offsets map[offsetKey]*Value
memForCall map[ID]*Value // For a call, need to know the unique selector that gets the mem.
}
// intPairTypes returns the pair of 32-bit int types needed to encode a 64-bit integer type on a target
@ -238,14 +239,20 @@ func (x *expandState) prAssignForArg(v *Value) abi.ABIParamAssignment {
if v.Op != OpArg {
panic(badVal("Wanted OpArg, instead saw", v))
}
name := v.Aux.(*ir.Name)
fPri := x.f.OwnAux.abiInfo
for _, a := range fPri.InParams() {
return ParamAssignmentForArgName(x.f, v.Aux.(*ir.Name))
}
// ParamAssignmentForArgName returns the ABIParamAssignment for f's arg with matching name.
func ParamAssignmentForArgName(f *Func, name *ir.Name) abi.ABIParamAssignment {
abiInfo := f.OwnAux.abiInfo
// This is unfortunate, but apparently the only way.
// TODO after register args stabilize, find a better way
for _, a := range abiInfo.InParams() {
if a.Name == name {
return a
}
}
panic(fmt.Errorf("Did not match param %v in prInfo %+v", name, fPri.InParams()))
panic(fmt.Errorf("Did not match param %v in prInfo %+v", name, abiInfo.InParams()))
}
// Calls that need lowering have some number of inputs, including a memory input,
@ -284,7 +291,7 @@ func (x *expandState) rewriteSelect(leaf *Value, selector *Value, offset int64,
case OpArg:
if !x.isAlreadyExpandedAggregateType(selector.Type) {
if leafType == selector.Type { // OpIData leads us here, sometimes.
leaf.copyOf(selector)
x.newArgToMemOrRegs(selector, leaf, offset, regOffset, leafType, leaf.Pos)
} else {
x.f.Fatalf("Unexpected OpArg type, selector=%s, leaf=%s\n", selector.LongString(), leaf.LongString())
}
@ -297,20 +304,8 @@ func (x *expandState) rewriteSelect(leaf *Value, selector *Value, offset int64,
case OpIData, OpStructSelect, OpArraySelect:
leafType = removeTrivialWrapperTypes(leaf.Type)
}
aux := selector.Aux
auxInt := selector.AuxInt + offset
if leaf.Block == selector.Block {
leaf.reset(OpArg)
leaf.Aux = aux
leaf.AuxInt = auxInt
leaf.Type = leafType
} else {
w := selector.Block.NewValue0IA(leaf.Pos, OpArg, leafType, auxInt, aux)
leaf.copyOf(w)
if x.debug {
fmt.Printf("\tnew %s\n", w.LongString())
}
}
x.newArgToMemOrRegs(selector, leaf, offset, regOffset, leafType, leaf.Pos)
for _, s := range x.namedSelects[selector] {
locs = append(locs, x.f.Names[s.locIndex])
}
@ -519,8 +514,23 @@ func (x *expandState) rewriteDereference(b *Block, base, a, mem *Value, offset,
// decomposeArgOrLoad is a helper for storeArgOrLoad.
// It decomposes a Load or an Arg into smaller parts, parameterized by the decomposeOne and decomposeTwo functions
// passed to it, and returns the new mem. If the type does not match one of the expected aggregate types, it returns nil instead.
// passed to it, and returns the new mem.
// If the type does not match one of the expected aggregate types, it returns nil instead.
// Parameters:
// pos -- the location of any generated code.
// b -- the block into which any generated code should normally be placed
// base -- for the stores that will ultimately be generated, the base to which the offset is applied. (Note this disappears in a future CL, folded into storeRc)
// source -- the value, possibly an aggregate, to be stored.
// mem -- the mem flowing into this decomposition (loads depend on it, stores updated it)
// t -- the type of the value to be stored
// offset -- if the value is stored in memory, it is stored at base + offset
// loadRegOffset -- regarding source as a value in registers, the register offset in ABI1. Meaningful only if source is OpArg.
// storeRc -- storeRC; if the value is stored in registers, this specifies the registers. StoreRc also identifies whether the target is registers or memory.
//
// TODO -- this needs cleanup; it just works for SSA-able aggregates, and won't fully generalize to register-args aggregates.
func (x *expandState) decomposeArgOrLoad(pos src.XPos, b *Block, base, source, mem *Value, t *types.Type, offset int64, loadRegOffset Abi1RO, storeRc registerCursor,
// For decompose One and Two, the additional offArg provides the offset from the beginning of "source", if it is in memory.
// offStore is combined to base to obtain a store destionation, like "offset" of decomposeArgOrLoad
decomposeOne func(x *expandState, pos src.XPos, b *Block, base, source, mem *Value, t1 *types.Type, offArg, offStore int64, loadRegOffset Abi1RO, storeRc registerCursor) *Value,
decomposeTwo func(x *expandState, pos src.XPos, b *Block, base, source, mem *Value, t1, t2 *types.Type, offArg, offStore int64, loadRegOffset Abi1RO, storeRc registerCursor) *Value) *Value {
u := source.Type
@ -530,7 +540,7 @@ func (x *expandState) decomposeArgOrLoad(pos src.XPos, b *Block, base, source, m
elemRO := x.regWidth(elem)
for i := int64(0); i < u.NumElem(); i++ {
elemOff := i * elem.Size()
mem = decomposeOne(x, pos, b, base, source, mem, elem, source.AuxInt+elemOff, offset+elemOff, loadRegOffset, storeRc.next(elem))
mem = decomposeOne(x, pos, b, base, source, mem, elem, elemOff, offset+elemOff, loadRegOffset, storeRc.next(elem))
loadRegOffset += elemRO
pos = pos.WithNotStmt()
}
@ -538,7 +548,7 @@ func (x *expandState) decomposeArgOrLoad(pos src.XPos, b *Block, base, source, m
case types.TSTRUCT:
for i := 0; i < u.NumFields(); i++ {
fld := u.Field(i)
mem = decomposeOne(x, pos, b, base, source, mem, fld.Type, source.AuxInt+fld.Offset, offset+fld.Offset, loadRegOffset, storeRc.next(fld.Type))
mem = decomposeOne(x, pos, b, base, source, mem, fld.Type, fld.Offset, offset+fld.Offset, loadRegOffset, storeRc.next(fld.Type))
loadRegOffset += x.regWidth(fld.Type)
pos = pos.WithNotStmt()
}
@ -548,20 +558,20 @@ func (x *expandState) decomposeArgOrLoad(pos src.XPos, b *Block, base, source, m
break
}
tHi, tLo := x.intPairTypes(t.Kind())
mem = decomposeOne(x, pos, b, base, source, mem, tHi, source.AuxInt+x.hiOffset, offset+x.hiOffset, loadRegOffset+x.hiRo, storeRc.plus(x.hiRo))
mem = decomposeOne(x, pos, b, base, source, mem, tHi, x.hiOffset, offset+x.hiOffset, loadRegOffset+x.hiRo, storeRc.plus(x.hiRo))
pos = pos.WithNotStmt()
return decomposeOne(x, pos, b, base, source, mem, tLo, source.AuxInt+x.lowOffset, offset+x.lowOffset, loadRegOffset+x.loRo, storeRc.plus(x.loRo))
return decomposeOne(x, pos, b, base, source, mem, tLo, x.lowOffset, offset+x.lowOffset, loadRegOffset+x.loRo, storeRc.plus(x.loRo))
case types.TINTER:
return decomposeTwo(x, pos, b, base, source, mem, x.typs.Uintptr, x.typs.BytePtr, source.AuxInt, offset, loadRegOffset, storeRc)
return decomposeTwo(x, pos, b, base, source, mem, x.typs.Uintptr, x.typs.BytePtr, 0, offset, loadRegOffset, storeRc)
case types.TSTRING:
return decomposeTwo(x, pos, b, base, source, mem, x.typs.BytePtr, x.typs.Int, source.AuxInt, offset, loadRegOffset, storeRc)
return decomposeTwo(x, pos, b, base, source, mem, x.typs.BytePtr, x.typs.Int, 0, offset, loadRegOffset, storeRc)
case types.TCOMPLEX64:
return decomposeTwo(x, pos, b, base, source, mem, x.typs.Float32, x.typs.Float32, source.AuxInt, offset, loadRegOffset, storeRc)
return decomposeTwo(x, pos, b, base, source, mem, x.typs.Float32, x.typs.Float32, 0, offset, loadRegOffset, storeRc)
case types.TCOMPLEX128:
return decomposeTwo(x, pos, b, base, source, mem, x.typs.Float64, x.typs.Float64, source.AuxInt, offset, loadRegOffset, storeRc)
return decomposeTwo(x, pos, b, base, source, mem, x.typs.Float64, x.typs.Float64, 0, offset, loadRegOffset, storeRc)
case types.TSLICE:
mem = decomposeOne(x, pos, b, base, source, mem, x.typs.BytePtr, source.AuxInt, offset, loadRegOffset, storeRc.next(x.typs.BytePtr))
return decomposeTwo(x, pos, b, base, source, mem, x.typs.Int, x.typs.Int, source.AuxInt+x.ptrSize, offset+x.ptrSize, loadRegOffset+RO_slice_len, storeRc)
mem = decomposeOne(x, pos, b, base, source, mem, x.typs.BytePtr, 0, offset, loadRegOffset, storeRc.next(x.typs.BytePtr))
return decomposeTwo(x, pos, b, base, source, mem, x.typs.Int, x.typs.Int, x.ptrSize, offset+x.ptrSize, loadRegOffset+RO_slice_len, storeRc)
}
return nil
}
@ -570,10 +580,11 @@ func (x *expandState) decomposeArgOrLoad(pos src.XPos, b *Block, base, source, m
// pos and b locate the store instruction, base is the base of the store target, 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, base, source, mem *Value, t *types.Type, offArg, offStore int64, loadRegOffset Abi1RO, storeRc registerCursor) *Value {
w := x.common[selKey{source, offArg, t.Width, t}]
w := x.commonArgs[selKey{source, offArg, t.Width, t}]
if w == nil {
w = source.Block.NewValue0IA(source.Pos, OpArg, t, offArg, source.Aux)
x.common[selKey{source, offArg, t.Width, t}] = w
// w = source.Block.NewValue0IA(source.Pos, OpArg, t, offArg, source.Aux)
w = x.newArgToMemOrRegs(source, w, offArg, loadRegOffset, t, pos)
// x.commonArgs[selKey{source, offArg, t.Width, t}] = w
}
return x.storeArgOrLoad(pos, b, base, w, mem, t, offStore, loadRegOffset, storeRc)
}
@ -867,7 +878,7 @@ func expandCalls(f *Func) {
ptrSize: f.Config.PtrSize,
namedSelects: make(map[*Value][]namedVal),
sdom: f.Sdom(),
common: make(map[selKey]*Value),
commonArgs: make(map[selKey]*Value),
offsets: make(map[offsetKey]*Value),
memForCall: make(map[ID]*Value),
}
@ -1110,7 +1121,7 @@ func expandCalls(f *Func) {
}
}
x.common = make(map[selKey]*Value)
x.commonSelectors = make(map[selKey]*Value)
// Rewrite duplicate selectors as copies where possible.
for i := len(allOrdered) - 1; i >= 0; i-- {
v := allOrdered[i]
@ -1153,15 +1164,15 @@ func expandCalls(f *Func) {
offset = size
}
sk := selKey{from: w, size: size, offset: offset, typ: typ}
dupe := x.common[sk]
dupe := x.commonSelectors[sk]
if dupe == nil {
x.common[sk] = v
x.commonSelectors[sk] = v
} else if x.sdom.IsAncestorEq(dupe.Block, v.Block) {
v.copyOf(dupe)
} else {
// Because values are processed in dominator order, the old common[s] will never dominate after a miss is seen.
// Installing the new value might match some future values.
x.common[sk] = v
x.commonSelectors[sk] = v
}
}
@ -1207,30 +1218,7 @@ func expandCalls(f *Func) {
for _, v := range b.Values {
switch v.Op {
case OpArg:
pa := x.prAssignForArg(v)
switch len(pa.Registers) {
case 0:
frameOff := v.Aux.(*ir.Name).FrameOffset()
if pa.Offset() != int32(frameOff+x.f.ABISelf.LocalsOffset()) {
panic(fmt.Errorf("Parameter assignment %d and OpArg.Aux frameOffset %d disagree, op=%s\n",
pa.Offset(), frameOff, v.LongString()))
}
case 1:
r := pa.Registers[0]
i := f.ABISelf.FloatIndexFor(r)
// TODO seems like this has implications for debugging. How does this affect the location?
if i >= 0 { // float PR
v.Op = OpArgFloatReg
} else {
v.Op = OpArgIntReg
i = int64(r)
}
v.AuxInt = i
default:
panic(badVal("Saw unexpanded OpArg", v))
}
x.rewriteArgToMemOrRegs(v)
case OpStaticLECall:
v.Op = OpStaticCall
// TODO need to insert all the register types.
@ -1263,3 +1251,107 @@ func expandCalls(f *Func) {
}
}
}
// rewriteArgToMemOrRegs converts OpArg v in-place into the register version of v,
// if that is appropriate.
func (x *expandState) rewriteArgToMemOrRegs(v *Value) *Value {
pa := x.prAssignForArg(v)
switch len(pa.Registers) {
case 0:
frameOff := v.Aux.(*ir.Name).FrameOffset()
if pa.Offset() != int32(frameOff+x.f.ABISelf.LocalsOffset()) {
panic(fmt.Errorf("Parameter assignment %d and OpArg.Aux frameOffset %d disagree, op=%s",
pa.Offset(), frameOff, v.LongString()))
}
case 1:
r := pa.Registers[0]
i := x.f.ABISelf.FloatIndexFor(r)
// TODO seems like this has implications for debugging. How does this affect the location?
if i >= 0 { // float PR
v.Op = OpArgFloatReg
} else {
v.Op = OpArgIntReg
i = int64(r)
}
v.Aux = &AuxNameOffset{v.Aux.(*ir.Name), 0}
v.AuxInt = i
default:
panic(badVal("Saw unexpanded OpArg", v))
}
return v
}
// newArgToMemOrRegs either rewrites toReplace into an OpArg referencing memory or into an OpArgXXXReg to a register,
// or rewrites it into a copy of the appropriate OpArgXXX. The actual OpArgXXX is determined by combining baseArg (an OpArg)
// with offset, regOffset, and t to determine which portion of it reference (either all or a part, in memory or in registers).
func (x *expandState) newArgToMemOrRegs(baseArg, toReplace *Value, offset int64, regOffset Abi1RO, t *types.Type, pos src.XPos) *Value {
key := selKey{baseArg, offset, t.Width, t}
w := x.commonArgs[key]
if w != nil {
if toReplace != nil {
toReplace.copyOf(w)
}
return w
}
pa := x.prAssignForArg(baseArg)
switch len(pa.Registers) {
case 0:
frameOff := baseArg.Aux.(*ir.Name).FrameOffset()
if pa.Offset() != int32(frameOff+x.f.ABISelf.LocalsOffset()) {
panic(fmt.Errorf("Parameter assignment %d and OpArg.Aux frameOffset %d disagree, op=%s",
pa.Offset(), frameOff, baseArg.LongString()))
}
aux := baseArg.Aux
auxInt := baseArg.AuxInt + offset
if toReplace != nil && toReplace.Block == baseArg.Block {
toReplace.reset(OpArg)
toReplace.Aux = aux
toReplace.AuxInt = auxInt
toReplace.Type = t
x.commonArgs[key] = toReplace
return toReplace
} else {
w := baseArg.Block.NewValue0IA(pos, OpArg, t, auxInt, aux)
x.commonArgs[key] = w
if x.debug {
fmt.Printf("\tnew %s\n", w.LongString())
}
if toReplace != nil {
toReplace.copyOf(w)
}
return w
}
default:
r := pa.Registers[regOffset]
auxInt := x.f.ABISelf.FloatIndexFor(r)
op := OpArgFloatReg
// TODO seems like this has implications for debugging. How does this affect the location?
if auxInt < 0 { // int (not float) parameter register
op = OpArgIntReg
auxInt = int64(r)
}
aux := &AuxNameOffset{baseArg.Aux.(*ir.Name), baseArg.AuxInt + offset}
if toReplace != nil && toReplace.Block == baseArg.Block {
toReplace.reset(op)
toReplace.Aux = aux
toReplace.AuxInt = auxInt
toReplace.Type = t
x.commonArgs[key] = toReplace
return toReplace
} else {
w := baseArg.Block.NewValue0IA(pos, op, t, auxInt, aux)
if x.debug {
fmt.Printf("\tnew %s\n", w.LongString())
}
x.commonArgs[key] = w
if toReplace != nil {
toReplace.copyOf(w)
}
return w
}
}
}

10
src/cmd/compile/internal/ssa/op.go
View File

@ -77,6 +77,16 @@ type Param struct {
Name *ir.Name // For OwnAux, need to prepend stores with Vardefs
}
type AuxNameOffset struct {
Name *ir.Name
Offset int64
}
func (a *AuxNameOffset) CanBeAnSSAAux() {}
func (a *AuxNameOffset) String() string {
return fmt.Sprintf("%s+%d", a.Name.Sym().Name, a.Offset)
}
type AuxCall struct {
// TODO(register args) this information is largely redundant with ../abi information, needs cleanup once new ABI is in place.
Fn *obj.LSym

3
src/cmd/compile/internal/ssa/regalloc.go
View File

@ -1517,6 +1517,9 @@ func (s *regAllocState) regalloc(f *Func) {
}
s.f.setHome(v, outLocs)
// Note that subsequent SelectX instructions will do the assignReg calls.
} else if v.Type.IsResults() {
// TODO register arguments need to make this work
panic("Oops, implement this.")
} else {
if r := outRegs[0]; r != noRegister {
s.assignReg(r, v, v)

15
src/cmd/compile/internal/ssa/stackalloc.go
View File

@ -151,13 +151,24 @@ func (s *stackAllocState) stackalloc() {
// Allocate args to their assigned locations.
for _, v := range f.Entry.Values {
if v.Op != OpArg {
if v.Op != OpArg { // && v.Op != OpArgFReg && v.Op != OpArgIReg {
continue
}
if v.Aux == nil {
f.Fatalf("%s has nil Aux\n", v.LongString())
}
loc := LocalSlot{N: v.Aux.(*ir.Name), Type: v.Type, Off: v.AuxInt}
var loc LocalSlot
var name *ir.Name
var offset int64
if v.Op == OpArg {
name = v.Aux.(*ir.Name)
offset = v.AuxInt
} else {
nameOff := v.Aux.(*AuxNameOffset)
name = nameOff.Name
offset = nameOff.Offset
}
loc = LocalSlot{N: name, Type: v.Type, Off: offset}
if f.pass.debug > stackDebug {
fmt.Printf("stackalloc %s to %s\n", v, loc)
}

2
src/cmd/compile/internal/ssa/tighten.go
View File

@ -18,7 +18,7 @@ func tighten(f *Func) {
continue
}
switch v.Op {
case OpPhi, OpArg, OpSelect0, OpSelect1, OpSelectN:
case OpPhi, OpArg, OpArgIntReg, OpArgFloatReg, OpSelect0, OpSelect1, OpSelectN:
// Phis need to stay in their block.
// Arg must stay in the entry block.
// Tuple selectors must stay with the tuple generator.

36
src/cmd/compile/internal/ssagen/ssa.go
View File

@ -539,16 +539,32 @@ func buildssa(fn *ir.Func, worker int) *ssa.Func {
// Populate SSAable arguments.
for _, n := range fn.Dcl {
if n.Class == ir.PPARAM && s.canSSA(n) {
var v *ssa.Value
if n.Sym().Name == ".fp" {
// Race-detector's get-caller-pc incantation is NOT a real Arg.
v = s.newValue0(ssa.OpGetCallerPC, n.Type())
} else {
v = s.newValue0A(ssa.OpArg, n.Type(), n)
if n.Class == ir.PPARAM {
if s.canSSA(n) {
var v *ssa.Value
if n.Sym().Name == ".fp" {
// Race-detector's get-caller-pc incantation is NOT a real Arg.
v = s.newValue0(ssa.OpGetCallerPC, n.Type())
} else {
v = s.newValue0A(ssa.OpArg, n.Type(), n)
}
s.vars[n] = v
s.addNamedValue(n, v) // This helps with debugging information, not needed for compilation itself.
} else if !s.canSSAName(n) { // I.e., the address was taken. The type may or may not be okay.
// If the value will arrive in registers,
// AND if it can be SSA'd (if it cannot, panic for now),
// THEN
// (1) receive it as an OpArg (but do not store its name in the var table)
// (2) store it to its spill location, which is its address as well.
paramAssignment := ssa.ParamAssignmentForArgName(s.f, n)
if len(paramAssignment.Registers) > 0 {
if !TypeOK(n.Type()) { // TODO register args -- if v is not an SSA-able type, must decompose, here.
panic(fmt.Errorf("Arg in registers is too big to be SSA'd, need to implement decomposition, type=%v, n=%v", n.Type(), n))
}
v := s.newValue0A(ssa.OpArg, n.Type(), n)
s.store(n.Type(), s.decladdrs[n], v)
}
}
s.vars[n] = v
s.addNamedValue(n, v) // This helps with debugging information, not needed for compilation itself.
}
}
@ -6545,6 +6561,8 @@ func genssa(f *ssa.Func, pp *objw.Progs) {
// memory arg needs no code
case ssa.OpArg:
// input args need no code
case ssa.OpArgIntReg, ssa.OpArgFloatReg:
CheckArgReg(v)
case ssa.OpSP, ssa.OpSB:
// nothing to do
case ssa.OpSelect0, ssa.OpSelect1, ssa.OpSelectN: