// CheckNames exists because of this comment in the SSA code documentation:
// "Many objects are nonetheless named to aid in debugging, but it is not essential that the names be either accurate or unambiguous. "
func CheckNames(f *ssa.Function) error {
names := make(map[string]*ssa.Instruction)
//fmt.Println("DEBUG Check Names for ", f.String())
for blk := range f.Blocks {
for ins := range f.Blocks[blk].Instrs {
instrVal, hasVal := f.Blocks[blk].Instrs[ins].(ssa.Value)
if hasVal {
register := instrVal.Name()
//fmt.Println("DEBUG name ", register)
val, found := names[register]
if found {
if val != &f.Blocks[blk].Instrs[ins] {
return fmt.Errorf("internal error, ssa register names not unique in function %s var name %s",
f.String(), register)
}
} else {
names[register] = &f.Blocks[blk].Instrs[ins]
}
}
}
}
return nil
}
// findIntrinsic returns the constraint generation function for an
// intrinsic function fn, or nil if the function should be handled normally.
//
func (a *analysis) findIntrinsic(fn *ssa.Function) intrinsic {
// Consult the *Function-keyed cache.
// A cached nil indicates a normal non-intrinsic function.
impl, ok := a.intrinsics[fn]
if !ok {
impl = intrinsicsByName[fn.String()] // may be nil
if a.isReflect(fn) {
if !a.config.Reflection {
impl = ext۰NoEffect // reflection disabled
} else if impl == nil {
// Ensure all "reflect" code is treated intrinsically.
impl = ext۰NotYetImplemented
}
} else if impl == nil && fn.Pkg != nil && fn.Pkg.Pkg.Path() == "runtime" {
// Ignore "runtime" (except SetFinalizer):
// it has few interesting effects on aliasing
// and is full of unsafe code we can't analyze.
impl = ext۰NoEffect
}
a.intrinsics[fn] = impl
}
return impl
}
func (fa *FairnessAnalysis) Visit(fn *ssa.Function) {
visitedBlk := make(map[*ssa.BasicBlock]bool)
fa.logger.Printf("Visiting: %s", fn.String())
for _, blk := range fn.Blocks {
if _, visited := visitedBlk[blk]; !visited {
visitedBlk[blk] = true
fa.logger.Printf(" block %d %s", blk.Index, blk.Comment)
// First consider blocks with loop initialisation blocks.
if blk.Comment == "rangeindex.loop" {
fa.total++
fa.logger.Println(color.GreenString("✓ range loops are fair"))
} else if blk.Comment == "rangechan.loop" {
fa.total++
hasClose := false
for _, ch := range fa.info.FindChan(blk.Instrs[0].(*ssa.UnOp).X) {
if ch.Type == ssabuilder.ChanClose {
fa.logger.Println(color.GreenString("✓ found corresponding close() - channel range likely fair"))
hasClose = true
}
}
if !hasClose {
fa.logger.Println(color.RedString("❌ range over channel w/o close() likely unfair (%s)", fa.info.FSet.Position(blk.Instrs[0].Pos())))
fa.unsafe++
}
} else if blk.Comment == "for.loop" {
fa.total++
if fa.isLikelyUnsafe(blk) {
fa.logger.Println(color.RedString("❌ for.loop maybe bad"))
fa.unsafe++
} else {
fa.logger.Println(color.GreenString("✓ for.loop is ok"))
}
} else { // Normal blocks (or loops without initialisation blocks).
if len(blk.Instrs) > 1 {
if ifInst, ok := blk.Instrs[len(blk.Instrs)-1].(*ssa.If); ok {
_, thenVisited := visitedBlk[ifInst.Block().Succs[0]]
_, elseVisited := visitedBlk[ifInst.Block().Succs[1]]
if thenVisited || elseVisited { // there is a loop!
fa.total++
if !fa.isCondFair(ifInst.Cond) {
fa.logger.Println(color.YellowString("Warning: recurring block condition probably unfair"))
fa.unsafe++
} else {
fa.logger.Println(color.GreenString("✓ recurring block is ok"))
}
}
} else if jInst, ok := blk.Instrs[len(blk.Instrs)-1].(*ssa.Jump); ok {
if _, visited := visitedBlk[jInst.Block().Succs[0]]; visited {
fa.total++
fa.unsafe++
fa.logger.Println(color.RedString("❌ infinite loop or recurring block, probably bad (%s)", fa.info.FSet.Position(blk.Instrs[0].Pos())))
}
}
}
}
}
}
}
// prepareCallFn prepares a caller Function to visit performing necessary context switching and returns a new callee Function.
// rcvr is non-nil if invoke call
func (caller *Function) prepareCallFn(common *ssa.CallCommon, fn *ssa.Function, rcvr ssa.Value) *Function {
callee := NewFunction(caller)
callee.Fn = fn
// This function was called before
if _, ok := callee.Prog.FuncInstance[callee.Fn]; ok {
callee.Prog.FuncInstance[callee.Fn]++
} else {
callee.Prog.FuncInstance[callee.Fn] = 0
}
callee.FuncDef.Name = fn.String()
callee.id = callee.Prog.FuncInstance[callee.Fn]
for i, param := range callee.Fn.Params {
var argCaller ssa.Value
if rcvr != nil {
if i == 0 {
argCaller = rcvr
} else {
argCaller = common.Args[i-1]
}
} else {
argCaller = common.Args[i]
}
if _, ok := argCaller.Type().(*types.Chan); ok {
callee.FuncDef.AddParams(&migo.Parameter{Caller: argCaller, Callee: param})
}
if inst, ok := caller.locals[argCaller]; ok {
callee.locals[param] = inst
callee.revlookup[argCaller.Name()] = param.Name()
// Copy array and struct from parent.
if elems, ok := caller.arrays[inst]; ok {
callee.arrays[inst] = elems
}
if fields, ok := caller.structs[inst]; ok {
callee.structs[inst] = fields
}
if maps, ok := caller.maps[inst]; ok {
callee.maps[inst] = maps
}
} else if c, ok := argCaller.(*ssa.Const); ok {
callee.locals[param] = &Const{c}
}
}
if inst, ok := caller.locals[common.Value]; ok {
if cap, ok := caller.Prog.closures[inst]; ok {
for i, fv := range callee.Fn.FreeVars {
callee.locals[fv] = cap[i]
if _, ok := derefType(fv.Type()).(*types.Chan); ok {
callee.FuncDef.AddParams(&migo.Parameter{Caller: fv, Callee: fv})
}
}
}
}
return callee
}
// callSSA interprets a call to function fn with arguments args,
// and lexical environment env, returning its result.
// callpos is the position of the callsite.
//
func callSSA(i *interpreter, caller *frame, callpos token.Pos, fn *ssa.Function, args []value, env []value) value {
if i.mode&EnableTracing != 0 {
fset := fn.Prog.Fset
// TODO(adonovan): fix: loc() lies for external functions.
fmt.Fprintf(os.Stderr, "Entering %s%s.\n", fn, loc(fset, fn.Pos()))
suffix := ""
if caller != nil {
suffix = ", resuming " + caller.fn.String() + loc(fset, callpos)
}
defer fmt.Fprintf(os.Stderr, "Leaving %s%s.\n", fn, suffix)
}
fr := &frame{
i: i,
caller: caller, // for panic/recover
fn: fn,
}
if fn.Parent() == nil {
name := fn.String()
if ext := externals[name]; ext != nil {
if i.mode&EnableTracing != 0 {
fmt.Fprintln(os.Stderr, "\t(external)")
}
return ext(fr, args)
}
if fn.Blocks == nil {
panic("no code for function: " + name)
}
}
fr.env = make(map[ssa.Value]value)
fr.block = fn.Blocks[0]
fr.locals = make([]value, len(fn.Locals))
for i, l := range fn.Locals {
fr.locals[i] = zero(deref(l.Type()))
fr.env[l] = &fr.locals[i]
}
for i, p := range fn.Params {
fr.env[p] = args[i]
}
for i, fv := range fn.FreeVars {
fr.env[fv] = env[i]
}
for fr.block != nil {
runFrame(fr)
}
// Destroy the locals to avoid accidental use after return.
for i := range fn.Locals {
fr.locals[i] = bad{}
}
return fr.result
}
func checkFn(fn *ssa.Function, prog *ssa.Program, ptrResult *pointer.Result, roots []*ssa.Function) {
nam := fn.String()
if strings.HasPrefix(strings.TrimPrefix(nam, "("), *prefix) {
hasPath := false
usedExternally := false
for _, r := range roots {
if r != nil {
nod, ok := ptrResult.CallGraph.Nodes[r]
if ok {
//fmt.Println("NODE root", r.Name())
pth := callgraph.PathSearch(nod,
func(n *callgraph.Node) bool {
if n == nil {
return false
}
if n.Func == fn {
for _, ine := range n.In {
if ine.Caller.Func.Pkg != fn.Pkg {
//fmt.Println("DEBUG diff? ",
// ine.Caller.Func.Pkg, fn.Pkg)
usedExternally = true
break
}
}
return true
}
return false
})
if pth != nil {
//fmt.Printf("DEBUG path from %v to %v = %v\n",
// r, fn, pth)
hasPath = true
break
}
}
}
}
isUpper := unicode.IsUpper(rune(fn.Name()[0]))
pos := fn.Pos()
//if strings.HasPrefix(nam, "(") && (!hasPath || (!usedExternally && isUpper)) {
// fmt.Println("bad Pos", pos, prog.Fset.Position(pos).String())
//}
loc := strings.TrimPrefix(
prog.Fset.Position(pos).String(),
gopath+"/src/"+*prefix+"/")
showFuncResult(loc, nam, hasPath, usedExternally, isUpper)
}
wg.Done()
}
// findIntrinsic returns the constraint generation function for an
// intrinsic function fn, or nil if the function should be handled normally.
//
func (a *analysis) findIntrinsic(fn *ssa.Function) intrinsic {
// Consult the *Function-keyed cache.
// A cached nil indicates a normal non-intrinsic function.
impl, ok := a.intrinsics[fn]
if !ok {
impl = intrinsicsByName[fn.String()] // may be nil
if a.isReflect(fn) {
if !a.config.Reflection {
impl = ext۰NoEffect // reflection disabled
} else if impl == nil {
// Ensure all "reflect" code is treated intrinsically.
impl = ext۰NotYetImplemented
}
}
a.intrinsics[fn] = impl
}
return impl
}
func (visit *visitor) function(fn *ssa.Function, isOvl isOverloaded) {
if !visit.seen[fn] { // been, exists := visit.seen[fn]; !been || !exists {
vprintln("DEBUG 1st visit to: ", fn.String())
visit.seen[fn] = true
visit.usesGR[fn] = false
if isOvl(fn) {
vprintln("DEBUG overloaded: ", fn.String())
return
}
if len(fn.Blocks) == 0 { // exclude functions that reference C/assembler code
// NOTE: not marked as seen, because we don't want to include in output
// if used, the symbol will be included in the golibruntime replacement packages
// TODO review
vprintln("DEBUG no code for: ", fn.String())
return // external functions cannot use goroutines
}
var buf [10]*ssa.Value // avoid alloc in common case
for _, b := range fn.Blocks {
for _, instr := range b.Instrs {
for _, op := range instr.Operands(buf[:0]) {
areRecursing := false
afn, isFn := (*op).(*ssa.Function)
if isFn {
if afn == fn {
areRecursing = true
}
visit.function(afn, isOvl)
if visit.usesGR[afn] {
vprintln("marked as using GR because referenced func uses GR")
visit.usesGR[fn] = true
}
vprintln(fn.Name(), " calls ", afn.Name())
}
// TODO, review if this code should be included
if !visit.usesGR[fn] {
if _, ok := (*op).(ssa.Value); ok {
typ := (*op).Type()
typ = DeRefUl(typ)
switch typ.(type) {
// TODO use oracle techniques to determine which interfaces or functions may require GR
case *types.Chan, *types.Interface:
visit.usesGR[fn] = true // may be too conservative
vprintln("marked as using GR because uses Chan/Interface")
case *types.Signature:
if !areRecursing {
if !isFn {
visit.usesGR[fn] = true
vprintln("marked as using GR because uses Signature")
}
}
}
}
}
}
if _, ok := instr.(*ssa.Call); ok {
switch instr.(*ssa.Call).Call.Value.(type) {
case *ssa.Builtin:
//NoOp
default:
cc := instr.(*ssa.Call).Common()
if cc != nil {
afn := cc.StaticCallee()
if afn != nil {
visit.function(afn, isOvl)
if visit.usesGR[afn] {
visit.usesGR[fn] = true
vprintln("marked as using GR because call target uses GR")
}
vprintln(fn.Name(), " calls ", afn.Name())
}
}
}
}
if !visit.usesGR[fn] {
switch instr.(type) {
case *ssa.Go, *ssa.MakeChan, *ssa.Defer, *ssa.Panic,
*ssa.Send, *ssa.Select:
vprintln("usesGR because uses Go...", fn.Name())
visit.usesGR[fn] = true
case *ssa.UnOp:
if instr.(*ssa.UnOp).Op.String() == "<-" {
vprintln("usesGR because uses <-", fn.Name())
visit.usesGR[fn] = true
}
}
}
}
}
}
}
func (u *unit) defineFunction(f *ssa.Function) {
// Only define functions from this package, or synthetic
// wrappers (which do not have a package).
if f.Pkg != nil && f.Pkg != u.pkg {
return
}
llfn := u.resolveFunctionGlobal(f)
linkage := u.getFunctionLinkage(f)
isMethod := f.Signature.Recv() != nil
// Methods cannot be referred to via a descriptor.
if !isMethod {
llfd := u.resolveFunctionDescriptorGlobal(f)
llfd.SetInitializer(llvm.ConstBitCast(llfn, llvm.PointerType(llvm.Int8Type(), 0)))
llfd.SetLinkage(linkage)
}
// We only need to emit a descriptor for functions without bodies.
if len(f.Blocks) == 0 {
return
}
ssaopt.LowerAllocsToStack(f)
if u.DumpSSA {
f.WriteTo(os.Stderr)
}
fr := newFrame(u, llfn)
defer fr.dispose()
fr.addCommonFunctionAttrs(fr.function)
fr.function.SetLinkage(linkage)
fr.logf("Define function: %s", f.String())
fti := u.llvmtypes.getSignatureInfo(f.Signature)
delete(u.undefinedFuncs, f)
fr.retInf = fti.retInf
// Push the compile unit and function onto the debug context.
if u.GenerateDebug {
u.debug.PushFunction(fr.function, f.Signature, f.Pos())
defer u.debug.PopFunction()
u.debug.SetLocation(fr.builder, f.Pos())
}
// If a function calls recover, we create a separate function to
// hold the real function, and this function calls __go_can_recover
// and bridges to it.
if callsRecover(f) {
fr = fr.bridgeRecoverFunc(fr.function, fti)
}
fr.blocks = make([]llvm.BasicBlock, len(f.Blocks))
fr.lastBlocks = make([]llvm.BasicBlock, len(f.Blocks))
for i, block := range f.Blocks {
fr.blocks[i] = llvm.AddBasicBlock(fr.function, fmt.Sprintf(".%d.%s", i, block.Comment))
}
fr.builder.SetInsertPointAtEnd(fr.blocks[0])
prologueBlock := llvm.InsertBasicBlock(fr.blocks[0], "prologue")
fr.builder.SetInsertPointAtEnd(prologueBlock)
// Map parameter positions to indices. We use this
// when processing locals to map back to parameters
// when generating debug metadata.
paramPos := make(map[token.Pos]int)
for i, param := range f.Params {
paramPos[param.Pos()] = i
llparam := fti.argInfos[i].decode(llvm.GlobalContext(), fr.builder, fr.builder)
if isMethod && i == 0 {
if _, ok := param.Type().Underlying().(*types.Pointer); !ok {
llparam = fr.builder.CreateBitCast(llparam, llvm.PointerType(fr.types.ToLLVM(param.Type()), 0), "")
llparam = fr.builder.CreateLoad(llparam, "")
}
}
fr.env[param] = newValue(llparam, param.Type())
}
// Load closure, extract free vars.
if len(f.FreeVars) > 0 {
for _, fv := range f.FreeVars {
fr.env[fv] = newValue(llvm.ConstNull(u.llvmtypes.ToLLVM(fv.Type())), fv.Type())
}
elemTypes := make([]llvm.Type, len(f.FreeVars)+1)
elemTypes[0] = llvm.PointerType(llvm.Int8Type(), 0) // function pointer
for i, fv := range f.FreeVars {
elemTypes[i+1] = u.llvmtypes.ToLLVM(fv.Type())
}
structType := llvm.StructType(elemTypes, false)
closure := fr.runtime.getClosure.call(fr)[0]
closure = fr.builder.CreateBitCast(closure, llvm.PointerType(structType, 0), "")
for i, fv := range f.FreeVars {
ptr := fr.builder.CreateStructGEP(closure, i+1, "")
ptr = fr.builder.CreateLoad(ptr, "")
fr.env[fv] = newValue(ptr, fv.Type())
}
}
// Allocate stack space for locals in the prologue block.
for _, local := range f.Locals {
typ := fr.llvmtypes.ToLLVM(deref(local.Type()))
alloca := fr.builder.CreateAlloca(typ, local.Comment)
fr.memsetZero(alloca, llvm.SizeOf(typ))
bcalloca := fr.builder.CreateBitCast(alloca, llvm.PointerType(llvm.Int8Type(), 0), "")
value := newValue(bcalloca, local.Type())
fr.env[local] = value
if fr.GenerateDebug {
paramIndex, ok := paramPos[local.Pos()]
if !ok {
paramIndex = -1
}
fr.debug.Declare(fr.builder, local, alloca, paramIndex)
}
}
// If this is the "init" function, enable init-specific optimizations.
if !isMethod && f.Name() == "init" {
fr.isInit = true
}
// If the function contains any defers, we must first create
// an unwind block. We can short-circuit the check for defers with
// f.Recover != nil.
if f.Recover != nil || hasDefer(f) {
fr.unwindBlock = llvm.AddBasicBlock(fr.function, "")
fr.frameptr = fr.builder.CreateAlloca(llvm.Int8Type(), "")
}
term := fr.builder.CreateBr(fr.blocks[0])
fr.allocaBuilder.SetInsertPointBefore(term)
for _, block := range f.DomPreorder() {
fr.translateBlock(block, fr.blocks[block.Index])
}
fr.fixupPhis()
if !fr.unwindBlock.IsNil() {
fr.setupUnwindBlock(f.Recover, f.Signature.Results())
}
// The init function needs to register the GC roots first. We do this
// after generating code for it because allocations may have caused
// additional GC roots to be created.
if fr.isInit {
fr.builder.SetInsertPointBefore(prologueBlock.FirstInstruction())
fr.registerGcRoots()
}
}