func (f *Function) instrIdxInBlock(instr ssa.Instruction) int {
block := instr.Block()
for i := 0; i < len(block.Instrs); i++ {
if block.Instrs[i] == instr {
return i
}
}
panic(ice("couldn't find instruction location in basic block"))
}
func aliveTest(ident *identifier, loc ssa.Instruction, after bool) bool {
// assume all identifiers not local to a basic block are alive
if !ident.isBlockLocal() {
return true
}
if loc == nil {
ice("invalid SSA instruction")
}
basicBlock := loc.Block()
if basicBlock == nil {
ice("cant get basic block for SSA instruction")
}
value := ident.ssaValue()
if value == nil {
// no ssa.Value, assume alive
return true
}
start := false
for _, i := range basicBlock.Instrs {
if !after {
if i == loc {
start = true
}
}
if start {
ops := i.Operands(nil)
for _, op := range ops {
// instruction at or after loc uses ident as an operand
if op != nil && *op == value {
return true
}
}
}
if after {
if i == loc {
start = true
}
}
}
// no instruction at or after loc uses ident as an operand
return false
}
func (f *Function) isAlive(loc ssa.Instruction, val ssa.Value) bool {
block := loc.Block()
instrIdx := f.instrIdxInBlock(loc)
if val.Referrers() == nil {
return false
}
for _, ref := range *val.Referrers() {
bk := ref.Block()
if bk.Index != block.Index {
continue
}
for i, _ := range bk.Instrs {
if i > instrIdx {
return true
}
}
}
return false
}
// visitInstr interprets a single ssa.Instruction within the activation
// record frame. It returns a continuation value indicating where to
// read the next instruction from.
func visitInstr(fr *frame, instr ssa.Instruction) continuation {
switch instr := instr.(type) {
case *ssa.DebugRef:
// no-op
case *ssa.UnOp:
fr.env[instr] = unop(instr, fr.get(instr.X))
case *ssa.BinOp:
fr.env[instr] = binop(instr.Op, instr.X.Type(), fr.get(instr.X), fr.get(instr.Y))
case *ssa.Call:
fn, args := prepareCall(fr, &instr.Call)
fr.env[instr] = call(fr.i, fr, instr.Pos(), fn, args)
case *ssa.ChangeInterface:
fr.env[instr] = fr.get(instr.X)
case *ssa.ChangeType:
fr.env[instr] = fr.get(instr.X) // (can't fail)
case *ssa.Convert:
fr.env[instr] = conv(instr.Type(), instr.X.Type(), fr.get(instr.X))
case *ssa.MakeInterface:
fr.env[instr] = iface{t: instr.X.Type(), v: fr.get(instr.X)}
case *ssa.Extract:
fr.env[instr] = fr.get(instr.Tuple).(tuple)[instr.Index]
case *ssa.Slice:
fr.env[instr] = slice(fr.get(instr.X), fr.get(instr.Low), fr.get(instr.High), fr.get(instr.Max))
case *ssa.Return:
switch len(instr.Results) {
case 0:
case 1:
fr.result = fr.get(instr.Results[0])
default:
var res []value
for _, r := range instr.Results {
res = append(res, fr.get(r))
}
fr.result = tuple(res)
}
fr.block = nil
return kReturn
case *ssa.RunDefers:
fr.runDefers()
case *ssa.Panic:
panic(targetPanic{fr.get(instr.X)})
case *ssa.Send:
fr.get(instr.Chan).(chan value) <- copyVal(fr.get(instr.X))
case *ssa.Store:
*fr.get(instr.Addr).(*value) = copyVal(fr.get(instr.Val))
case *ssa.If:
succ := 1
if fr.get(instr.Cond).(bool) {
succ = 0
}
fr.prevBlock, fr.block = fr.block, fr.block.Succs[succ]
return kJump
case *ssa.Jump:
fr.prevBlock, fr.block = fr.block, fr.block.Succs[0]
return kJump
case *ssa.Defer:
fn, args := prepareCall(fr, &instr.Call)
fr.defers = &deferred{
fn: fn,
args: args,
instr: instr,
tail: fr.defers,
}
case *ssa.Go:
fn, args := prepareCall(fr, &instr.Call)
go call(fr.i, nil, instr.Pos(), fn, args)
case *ssa.MakeChan:
fr.env[instr] = make(chan value, asInt(fr.get(instr.Size)))
case *ssa.Alloc:
var addr *value
if instr.Heap {
// new
addr = new(value)
fr.env[instr] = addr
} else {
// local
addr = fr.env[instr].(*value)
}
*addr = zero(deref(instr.Type()))
case *ssa.MakeSlice:
slice := make([]value, asInt(fr.get(instr.Cap)))
tElt := instr.Type().Underlying().(*types.Slice).Elem()
for i := range slice {
slice[i] = zero(tElt)
}
fr.env[instr] = slice[:asInt(fr.get(instr.Len))]
case *ssa.MakeMap:
reserve := 0
if instr.Reserve != nil {
reserve = asInt(fr.get(instr.Reserve))
}
fr.env[instr] = makeMap(instr.Type().Underlying().(*types.Map).Key(), reserve)
case *ssa.Range:
fr.env[instr] = rangeIter(fr.get(instr.X), instr.X.Type())
case *ssa.Next:
fr.env[instr] = fr.get(instr.Iter).(iter).next()
case *ssa.FieldAddr:
x := fr.get(instr.X)
fr.env[instr] = &(*x.(*value)).(structure)[instr.Field]
case *ssa.Field:
fr.env[instr] = copyVal(fr.get(instr.X).(structure)[instr.Field])
case *ssa.IndexAddr:
x := fr.get(instr.X)
idx := fr.get(instr.Index)
switch x := x.(type) {
case []value:
fr.env[instr] = &x[asInt(idx)]
case *value: // *array
fr.env[instr] = &(*x).(array)[asInt(idx)]
default:
panic(fmt.Sprintf("unexpected x type in IndexAddr: %T", x))
}
case *ssa.Index:
fr.env[instr] = copyVal(fr.get(instr.X).(array)[asInt(fr.get(instr.Index))])
case *ssa.Lookup:
fr.env[instr] = lookup(instr, fr.get(instr.X), fr.get(instr.Index))
case *ssa.MapUpdate:
m := fr.get(instr.Map)
key := fr.get(instr.Key)
v := fr.get(instr.Value)
switch m := m.(type) {
case map[value]value:
m[key] = v
case *hashmap:
m.insert(key.(hashable), v)
default:
panic(fmt.Sprintf("illegal map type: %T", m))
}
case *ssa.TypeAssert:
fr.env[instr] = typeAssert(fr.i, instr, fr.get(instr.X).(iface))
case *ssa.MakeClosure:
var bindings []value
for _, binding := range instr.Bindings {
bindings = append(bindings, fr.get(binding))
}
fr.env[instr] = &closure{instr.Fn.(*ssa.Function), bindings}
case *ssa.Phi:
for i, pred := range instr.Block().Preds {
if fr.prevBlock == pred {
fr.env[instr] = fr.get(instr.Edges[i])
break
}
}
case *ssa.Select:
var cases []reflect.SelectCase
if !instr.Blocking {
cases = append(cases, reflect.SelectCase{
Dir: reflect.SelectDefault,
})
}
for _, state := range instr.States {
var dir reflect.SelectDir
if state.Dir == types.RecvOnly {
dir = reflect.SelectRecv
} else {
dir = reflect.SelectSend
}
var send reflect.Value
if state.Send != nil {
send = reflect.ValueOf(fr.get(state.Send))
}
cases = append(cases, reflect.SelectCase{
Dir: dir,
Chan: reflect.ValueOf(fr.get(state.Chan)),
Send: send,
})
}
chosen, recv, recvOk := reflect.Select(cases)
if !instr.Blocking {
chosen-- // default case should have index -1.
}
r := tuple{chosen, recvOk}
for i, st := range instr.States {
if st.Dir == types.RecvOnly {
var v value
if i == chosen && recvOk {
// No need to copy since send makes an unaliased copy.
v = recv.Interface().(value)
} else {
v = zero(st.Chan.Type().Underlying().(*types.Chan).Elem())
}
r = append(r, v)
}
}
fr.env[instr] = r
default:
panic(fmt.Sprintf("unexpected instruction: %T", instr))
}
// if val, ok := instr.(ssa.Value); ok {
// fmt.Println(toString(fr.env[val])) // debugging
// }
return kNext
}
func (fr *frame) instruction(instr ssa.Instruction) {
fr.logf("[%T] %v @ %s\n", instr, instr, fr.pkg.Prog.Fset.Position(instr.Pos()))
if fr.GenerateDebug {
fr.debug.SetLocation(fr.builder, instr.Pos())
}
switch instr := instr.(type) {
case *ssa.Alloc:
typ := deref(instr.Type())
llvmtyp := fr.llvmtypes.ToLLVM(typ)
var value llvm.Value
if !instr.Heap {
value = fr.env[instr].value
fr.memsetZero(value, llvm.SizeOf(llvmtyp))
} else if fr.isInit && fr.shouldStaticallyAllocate(instr) {
// If this is the init function and we think it may be beneficial,
// allocate memory statically in the object file rather than on the
// heap. This allows us to optimize constant stores into such
// variables as static initializations.
global := llvm.AddGlobal(fr.module.Module, llvmtyp, "")
global.SetLinkage(llvm.InternalLinkage)
fr.addGlobal(global, typ)
ptr := llvm.ConstBitCast(global, llvm.PointerType(llvm.Int8Type(), 0))
fr.env[instr] = newValue(ptr, instr.Type())
} else {
value = fr.createTypeMalloc(typ)
value.SetName(instr.Comment)
value = fr.builder.CreateBitCast(value, llvm.PointerType(llvm.Int8Type(), 0), "")
fr.env[instr] = newValue(value, instr.Type())
}
case *ssa.BinOp:
lhs, rhs := fr.value(instr.X), fr.value(instr.Y)
fr.env[instr] = fr.binaryOp(lhs, instr.Op, rhs)
case *ssa.Call:
tuple := fr.callInstruction(instr)
if len(tuple) == 1 {
fr.env[instr] = tuple[0]
} else {
fr.tuples[instr] = tuple
}
case *ssa.ChangeInterface:
x := fr.value(instr.X)
// The source type must be a non-empty interface,
// as ChangeInterface cannot fail (E2I may fail).
if instr.Type().Underlying().(*types.Interface).NumMethods() > 0 {
x = fr.changeInterface(x, instr.Type(), false)
} else {
x = fr.convertI2E(x)
}
fr.env[instr] = x
case *ssa.ChangeType:
value := fr.llvmvalue(instr.X)
if _, ok := instr.Type().Underlying().(*types.Pointer); ok {
value = fr.builder.CreateBitCast(value, fr.llvmtypes.ToLLVM(instr.Type()), "")
}
fr.env[instr] = newValue(value, instr.Type())
case *ssa.Convert:
v := fr.value(instr.X)
fr.env[instr] = fr.convert(v, instr.Type())
case *ssa.Defer:
fn, arg := fr.createThunk(instr)
fr.runtime.Defer.call(fr, fr.frameptr, fn, arg)
case *ssa.Extract:
var elem llvm.Value
if t, ok := fr.tuples[instr.Tuple]; ok {
elem = t[instr.Index].value
} else {
tuple := fr.llvmvalue(instr.Tuple)
elem = fr.builder.CreateExtractValue(tuple, instr.Index, instr.Name())
}
elemtyp := instr.Type()
fr.env[instr] = newValue(elem, elemtyp)
case *ssa.Field:
fieldtyp := instr.Type()
if p, ok := fr.ptr[instr.X]; ok {
field := fr.builder.CreateStructGEP(p, instr.Field, instr.Name())
if fr.canAvoidElementLoad(*instr.Referrers()) {
fr.ptr[instr] = field
} else {
fr.env[instr] = newValue(fr.builder.CreateLoad(field, ""), fieldtyp)
}
} else {
value := fr.llvmvalue(instr.X)
field := fr.builder.CreateExtractValue(value, instr.Field, instr.Name())
fr.env[instr] = newValue(field, fieldtyp)
}
case *ssa.FieldAddr:
ptr := fr.llvmvalue(instr.X)
fr.nilCheck(instr.X, ptr)
xtyp := instr.X.Type().Underlying().(*types.Pointer).Elem()
ptrtyp := llvm.PointerType(fr.llvmtypes.ToLLVM(xtyp), 0)
ptr = fr.builder.CreateBitCast(ptr, ptrtyp, "")
fieldptr := fr.builder.CreateStructGEP(ptr, instr.Field, instr.Name())
fieldptr = fr.builder.CreateBitCast(fieldptr, llvm.PointerType(llvm.Int8Type(), 0), "")
fieldptrtyp := instr.Type()
fr.env[instr] = newValue(fieldptr, fieldptrtyp)
case *ssa.Go:
fn, arg := fr.createThunk(instr)
fr.runtime.Go.call(fr, fn, arg)
case *ssa.If:
cond := fr.llvmvalue(instr.Cond)
block := instr.Block()
trueBlock := fr.block(block.Succs[0])
falseBlock := fr.block(block.Succs[1])
cond = fr.builder.CreateTrunc(cond, llvm.Int1Type(), "")
fr.builder.CreateCondBr(cond, trueBlock, falseBlock)
case *ssa.Index:
var arrayptr llvm.Value
if ptr, ok := fr.ptr[instr.X]; ok {
arrayptr = ptr
} else {
array := fr.llvmvalue(instr.X)
arrayptr = fr.allocaBuilder.CreateAlloca(array.Type(), "")
fr.builder.CreateStore(array, arrayptr)
}
index := fr.llvmvalue(instr.Index)
arraytyp := instr.X.Type().Underlying().(*types.Array)
arraylen := llvm.ConstInt(fr.llvmtypes.inttype, uint64(arraytyp.Len()), false)
// The index may not have been promoted to int (for example, if it
// came from a composite literal).
index = fr.createZExtOrTrunc(index, fr.types.inttype, "")
// Bounds checking: 0 <= index < len
zero := llvm.ConstNull(fr.types.inttype)
i0 := fr.builder.CreateICmp(llvm.IntSLT, index, zero, "")
li := fr.builder.CreateICmp(llvm.IntSLE, arraylen, index, "")
cond := fr.builder.CreateOr(i0, li, "")
fr.condBrRuntimeError(cond, gccgoRuntimeErrorARRAY_INDEX_OUT_OF_BOUNDS)
addr := fr.builder.CreateGEP(arrayptr, []llvm.Value{zero, index}, "")
if fr.canAvoidElementLoad(*instr.Referrers()) {
fr.ptr[instr] = addr
} else {
fr.env[instr] = newValue(fr.builder.CreateLoad(addr, ""), instr.Type())
}
case *ssa.IndexAddr:
x := fr.llvmvalue(instr.X)
index := fr.llvmvalue(instr.Index)
var arrayptr, arraylen llvm.Value
var elemtyp types.Type
var errcode uint64
switch typ := instr.X.Type().Underlying().(type) {
case *types.Slice:
elemtyp = typ.Elem()
arrayptr = fr.builder.CreateExtractValue(x, 0, "")
arraylen = fr.builder.CreateExtractValue(x, 1, "")
errcode = gccgoRuntimeErrorSLICE_INDEX_OUT_OF_BOUNDS
case *types.Pointer: // *array
arraytyp := typ.Elem().Underlying().(*types.Array)
elemtyp = arraytyp.Elem()
fr.nilCheck(instr.X, x)
arrayptr = x
arraylen = llvm.ConstInt(fr.llvmtypes.inttype, uint64(arraytyp.Len()), false)
errcode = gccgoRuntimeErrorARRAY_INDEX_OUT_OF_BOUNDS
}
// The index may not have been promoted to int (for example, if it
// came from a composite literal).
index = fr.createZExtOrTrunc(index, fr.types.inttype, "")
// Bounds checking: 0 <= index < len
zero := llvm.ConstNull(fr.types.inttype)
i0 := fr.builder.CreateICmp(llvm.IntSLT, index, zero, "")
li := fr.builder.CreateICmp(llvm.IntSLE, arraylen, index, "")
cond := fr.builder.CreateOr(i0, li, "")
fr.condBrRuntimeError(cond, errcode)
ptrtyp := llvm.PointerType(fr.llvmtypes.ToLLVM(elemtyp), 0)
arrayptr = fr.builder.CreateBitCast(arrayptr, ptrtyp, "")
addr := fr.builder.CreateGEP(arrayptr, []llvm.Value{index}, "")
addr = fr.builder.CreateBitCast(addr, llvm.PointerType(llvm.Int8Type(), 0), "")
fr.env[instr] = newValue(addr, types.NewPointer(elemtyp))
case *ssa.Jump:
succ := instr.Block().Succs[0]
fr.builder.CreateBr(fr.block(succ))
case *ssa.Lookup:
x := fr.value(instr.X)
index := fr.value(instr.Index)
if isString(x.Type().Underlying()) {
fr.env[instr] = fr.stringIndex(x, index)
} else {
v, ok := fr.mapLookup(x, index)
if instr.CommaOk {
fr.tuples[instr] = []*govalue{v, ok}
} else {
fr.env[instr] = v
}
}
case *ssa.MakeChan:
fr.env[instr] = fr.makeChan(instr.Type(), fr.value(instr.Size))
case *ssa.MakeClosure:
llfn := fr.resolveFunctionGlobal(instr.Fn.(*ssa.Function))
llfn = llvm.ConstBitCast(llfn, llvm.PointerType(llvm.Int8Type(), 0))
fn := newValue(llfn, instr.Fn.(*ssa.Function).Signature)
bindings := make([]*govalue, len(instr.Bindings))
for i, binding := range instr.Bindings {
bindings[i] = fr.value(binding)
}
fr.env[instr] = fr.makeClosure(fn, bindings)
case *ssa.MakeInterface:
// fr.ptr[instr.X] will be set if a pointer load was elided by canAvoidLoad
if ptr, ok := fr.ptr[instr.X]; ok {
fr.env[instr] = fr.makeInterfaceFromPointer(ptr, instr.X.Type(), instr.Type())
} else {
receiver := fr.llvmvalue(instr.X)
fr.env[instr] = fr.makeInterface(receiver, instr.X.Type(), instr.Type())
}
case *ssa.MakeMap:
fr.env[instr] = fr.makeMap(instr.Type(), fr.value(instr.Reserve))
case *ssa.MakeSlice:
length := fr.value(instr.Len)
capacity := fr.value(instr.Cap)
fr.env[instr] = fr.makeSlice(instr.Type(), length, capacity)
case *ssa.MapUpdate:
m := fr.value(instr.Map)
k := fr.value(instr.Key)
v := fr.value(instr.Value)
fr.mapUpdate(m, k, v)
case *ssa.Next:
iter := fr.tuples[instr.Iter]
if instr.IsString {
fr.tuples[instr] = fr.stringIterNext(iter)
} else {
fr.tuples[instr] = fr.mapIterNext(iter)
}
case *ssa.Panic:
arg := fr.value(instr.X)
fr.callPanic(arg)
case *ssa.Phi:
typ := instr.Type()
phi := fr.builder.CreatePHI(fr.llvmtypes.ToLLVM(typ), instr.Comment)
fr.env[instr] = newValue(phi, typ)
fr.phis = append(fr.phis, pendingPhi{instr, phi})
case *ssa.Range:
x := fr.value(instr.X)
switch x.Type().Underlying().(type) {
case *types.Map:
fr.tuples[instr] = fr.mapIterInit(x)
case *types.Basic: // string
fr.tuples[instr] = fr.stringIterInit(x)
default:
panic(fmt.Sprintf("unhandled range for type %T", x.Type()))
}
case *ssa.Return:
vals := make([]llvm.Value, len(instr.Results))
for i, res := range instr.Results {
vals[i] = fr.llvmvalue(res)
}
fr.retInf.encode(llvm.GlobalContext(), fr.allocaBuilder, fr.builder, vals)
case *ssa.RunDefers:
fr.runDefers()
case *ssa.Select:
states := make([]selectState, len(instr.States))
for i, state := range instr.States {
states[i] = selectState{
Dir: state.Dir,
Chan: fr.value(state.Chan),
Send: fr.value(state.Send),
}
}
index, recvOk, recvElems := fr.chanSelect(states, instr.Blocking)
tuple := append([]*govalue{index, recvOk}, recvElems...)
fr.tuples[instr] = tuple
case *ssa.Send:
fr.chanSend(fr.value(instr.Chan), fr.value(instr.X))
case *ssa.Slice:
x := fr.llvmvalue(instr.X)
low := fr.llvmvalue(instr.Low)
high := fr.llvmvalue(instr.High)
max := fr.llvmvalue(instr.Max)
slice := fr.slice(x, instr.X.Type(), low, high, max)
fr.env[instr] = newValue(slice, instr.Type())
case *ssa.Store:
addr := fr.llvmvalue(instr.Addr)
value := fr.llvmvalue(instr.Val)
addr = fr.builder.CreateBitCast(addr, llvm.PointerType(value.Type(), 0), "")
// If this is the init function, see if we can simulate the effect
// of the store in a global's initializer, in which case we can avoid
// generating code for it.
if !fr.isInit || !fr.maybeStoreInInitializer(value, addr) {
fr.nilCheck(instr.Addr, addr)
fr.builder.CreateStore(value, addr)
}
case *ssa.TypeAssert:
x := fr.value(instr.X)
if instr.CommaOk {
v, ok := fr.interfaceTypeCheck(x, instr.AssertedType)
fr.tuples[instr] = []*govalue{v, ok}
} else {
fr.env[instr] = fr.interfaceTypeAssert(x, instr.AssertedType)
}
case *ssa.UnOp:
operand := fr.value(instr.X)
switch instr.Op {
case token.ARROW:
x, ok := fr.chanRecv(operand, instr.CommaOk)
if instr.CommaOk {
fr.tuples[instr] = []*govalue{x, ok}
} else {
fr.env[instr] = x
}
case token.MUL:
fr.nilCheck(instr.X, operand.value)
if !fr.canAvoidLoad(instr, operand.value) {
// The bitcast is necessary to handle recursive pointer loads.
llptr := fr.builder.CreateBitCast(operand.value, llvm.PointerType(fr.llvmtypes.ToLLVM(instr.Type()), 0), "")
fr.env[instr] = newValue(fr.builder.CreateLoad(llptr, ""), instr.Type())
}
default:
fr.env[instr] = fr.unaryOp(operand, instr.Op)
}
default:
panic(fmt.Sprintf("unhandled: %v", instr))
}
}