// Copyright 2013 The Go Authors. All rights reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. package pointer // This package defines the treatment of intrinsics, i.e. library // functions requiring special analytical treatment. // // Most of these are C or assembly functions, but even some Go // functions require may special treatment if the analysis completely // replaces the implementation of an API such as reflection. // TODO(adonovan): support a means of writing analytic summaries in // the target code, so that users can summarise the effects of their // own C functions using a snippet of Go. import ( "fmt" "go/types" "golang.org/x/tools/go/ssa" ) // Instances of 'intrinsic' generate analysis constraints for calls to // intrinsic functions. // Implementations may exploit information from the calling site // via cgn.callersite; for shared contours this is nil. type intrinsic func(a *analysis, cgn *cgnode) // Initialized in explicit init() to defeat (spurious) initialization // cycle error. var intrinsicsByName = make(map[string]intrinsic) func init() { // Key strings are from Function.String(). // That little dot ۰ is an Arabic zero numeral (U+06F0), // categories [Nd]. for name, fn := range map[string]intrinsic{ // Other packages. "bytes.Equal": ext۰NoEffect, "bytes.IndexByte": ext۰NoEffect, "crypto/aes.decryptBlockAsm": ext۰NoEffect, "crypto/aes.encryptBlockAsm": ext۰NoEffect, "crypto/aes.expandKeyAsm": ext۰NoEffect, "crypto/aes.hasAsm": ext۰NoEffect, "crypto/md5.block": ext۰NoEffect, "crypto/rc4.xorKeyStream": ext۰NoEffect, "crypto/sha1.block": ext۰NoEffect, "crypto/sha256.block": ext۰NoEffect, "hash/crc32.castagnoliSSE42": ext۰NoEffect, "hash/crc32.haveSSE42": ext۰NoEffect, "math.Abs": ext۰NoEffect, "math.Acos": ext۰NoEffect, "math.Asin": ext۰NoEffect, "math.Atan": ext۰NoEffect, "math.Atan2": ext۰NoEffect, "math.Ceil": ext۰NoEffect, "math.Cos": ext۰NoEffect, "math.Dim": ext۰NoEffect, "math.Exp": ext۰NoEffect, "math.Exp2": ext۰NoEffect, "math.Expm1": ext۰NoEffect, "math.Float32bits": ext۰NoEffect, "math.Float32frombits": ext۰NoEffect, "math.Float64bits": ext۰NoEffect, "math.Float64frombits": ext۰NoEffect, "math.Floor": ext۰NoEffect, "math.Frexp": ext۰NoEffect, "math.Hypot": ext۰NoEffect, "math.Ldexp": ext۰NoEffect, "math.Log": ext۰NoEffect, "math.Log10": ext۰NoEffect, "math.Log1p": ext۰NoEffect, "math.Log2": ext۰NoEffect, "math.Max": ext۰NoEffect, "math.Min": ext۰NoEffect, "math.Mod": ext۰NoEffect, "math.Modf": ext۰NoEffect, "math.Remainder": ext۰NoEffect, "math.Sin": ext۰NoEffect, "math.Sincos": ext۰NoEffect, "math.Sqrt": ext۰NoEffect, "math.Tan": ext۰NoEffect, "math.Trunc": ext۰NoEffect, "math/big.addMulVVW": ext۰NoEffect, "math/big.addVV": ext۰NoEffect, "math/big.addVW": ext۰NoEffect, "math/big.bitLen": ext۰NoEffect, "math/big.divWVW": ext۰NoEffect, "math/big.divWW": ext۰NoEffect, "math/big.mulAddVWW": ext۰NoEffect, "math/big.mulWW": ext۰NoEffect, "math/big.shlVU": ext۰NoEffect, "math/big.shrVU": ext۰NoEffect, "math/big.subVV": ext۰NoEffect, "math/big.subVW": ext۰NoEffect, "net.runtime_Semacquire": ext۰NoEffect, "net.runtime_Semrelease": ext۰NoEffect, "net.runtime_pollClose": ext۰NoEffect, "net.runtime_pollOpen": ext۰NoEffect, "net.runtime_pollReset": ext۰NoEffect, "net.runtime_pollServerInit": ext۰NoEffect, "net.runtime_pollSetDeadline": ext۰NoEffect, "net.runtime_pollUnblock": ext۰NoEffect, "net.runtime_pollWait": ext۰NoEffect, "net.runtime_pollWaitCanceled": ext۰NoEffect, "os.epipecheck": ext۰NoEffect, // All other runtime functions are treated as NoEffect. "runtime.SetFinalizer": ext۰runtime۰SetFinalizer, "strings.IndexByte": ext۰NoEffect, "sync.runtime_Semacquire": ext۰NoEffect, "sync.runtime_Semrelease": ext۰NoEffect, "sync.runtime_Syncsemacquire": ext۰NoEffect, "sync.runtime_Syncsemcheck": ext۰NoEffect, "sync.runtime_Syncsemrelease": ext۰NoEffect, "sync.runtime_procPin": ext۰NoEffect, "sync.runtime_procUnpin": ext۰NoEffect, "sync.runtime_registerPool": ext۰NoEffect, "sync/atomic.AddInt32": ext۰NoEffect, "sync/atomic.AddInt64": ext۰NoEffect, "sync/atomic.AddUint32": ext۰NoEffect, "sync/atomic.AddUint64": ext۰NoEffect, "sync/atomic.AddUintptr": ext۰NoEffect, "sync/atomic.CompareAndSwapInt32": ext۰NoEffect, "sync/atomic.CompareAndSwapUint32": ext۰NoEffect, "sync/atomic.CompareAndSwapUint64": ext۰NoEffect, "sync/atomic.CompareAndSwapUintptr": ext۰NoEffect, "sync/atomic.LoadInt32": ext۰NoEffect, "sync/atomic.LoadInt64": ext۰NoEffect, "sync/atomic.LoadPointer": ext۰NoEffect, // ignore unsafe.Pointers "sync/atomic.LoadUint32": ext۰NoEffect, "sync/atomic.LoadUint64": ext۰NoEffect, "sync/atomic.LoadUintptr": ext۰NoEffect, "sync/atomic.StoreInt32": ext۰NoEffect, "sync/atomic.StorePointer": ext۰NoEffect, // ignore unsafe.Pointers "sync/atomic.StoreUint32": ext۰NoEffect, "sync/atomic.StoreUintptr": ext۰NoEffect, "syscall.Close": ext۰NoEffect, "syscall.Exit": ext۰NoEffect, "syscall.Getpid": ext۰NoEffect, "syscall.Getwd": ext۰NoEffect, "syscall.Kill": ext۰NoEffect, "syscall.RawSyscall": ext۰NoEffect, "syscall.RawSyscall6": ext۰NoEffect, "syscall.Syscall": ext۰NoEffect, "syscall.Syscall6": ext۰NoEffect, "syscall.runtime_AfterFork": ext۰NoEffect, "syscall.runtime_BeforeFork": ext۰NoEffect, "syscall.setenv_c": ext۰NoEffect, "time.Sleep": ext۰NoEffect, "time.now": ext۰NoEffect, "time.startTimer": ext۰time۰startTimer, "time.stopTimer": ext۰NoEffect, } { intrinsicsByName[name] = fn } } // 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 } // isReflect reports whether fn belongs to the "reflect" package. func (a *analysis) isReflect(fn *ssa.Function) bool { if a.reflectValueObj == nil { return false // "reflect" package not loaded } reflectPackage := a.reflectValueObj.Pkg() if fn.Pkg != nil && fn.Pkg.Pkg == reflectPackage { return true } // Synthetic wrappers have a nil Pkg, so they slip through the // previous check. Check the receiver package. // TODO(adonovan): should synthetic wrappers have a non-nil Pkg? if recv := fn.Signature.Recv(); recv != nil { if named, ok := deref(recv.Type()).(*types.Named); ok { if named.Obj().Pkg() == reflectPackage { return true // e.g. wrapper of (reflect.Value).f } } } return false } // A trivial intrinsic suitable for any function that does not: // 1) induce aliases between its arguments or any global variables; // 2) call any functions; or // 3) create any labels. // // Many intrinsics (such as CompareAndSwapInt32) have a fourth kind of // effect: loading or storing through a pointer. Though these could // be significant, we deliberately ignore them because they are // generally not worth the effort. // // We sometimes violate condition #3 if the function creates only // non-function labels, as the control-flow graph is still sound. // func ext۰NoEffect(a *analysis, cgn *cgnode) {} func ext۰NotYetImplemented(a *analysis, cgn *cgnode) { fn := cgn.fn a.warnf(fn.Pos(), "unsound: intrinsic treatment of %s not yet implemented", fn) } // ---------- func runtime.SetFinalizer(x, f interface{}) ---------- // runtime.SetFinalizer(x, f) type runtimeSetFinalizerConstraint struct { targets nodeid // (indirect) f nodeid // (ptr) x nodeid } func (c *runtimeSetFinalizerConstraint) ptr() nodeid { return c.f } func (c *runtimeSetFinalizerConstraint) presolve(h *hvn) { h.markIndirect(onodeid(c.targets), "SetFinalizer.targets") } func (c *runtimeSetFinalizerConstraint) renumber(mapping []nodeid) { c.targets = mapping[c.targets] c.f = mapping[c.f] c.x = mapping[c.x] } func (c *runtimeSetFinalizerConstraint) String() string { return fmt.Sprintf("runtime.SetFinalizer(n%d, n%d)", c.x, c.f) } func (c *runtimeSetFinalizerConstraint) solve(a *analysis, delta *nodeset) { for _, fObj := range delta.AppendTo(a.deltaSpace) { tDyn, f, indirect := a.taggedValue(nodeid(fObj)) if indirect { // TODO(adonovan): we'll need to implement this // when we start creating indirect tagged objects. panic("indirect tagged object") } tSig, ok := tDyn.Underlying().(*types.Signature) if !ok { continue // not a function } if tSig.Recv() != nil { panic(tSig) } if tSig.Params().Len() != 1 { continue // not a unary function } // Extract x to tmp. tx := tSig.Params().At(0).Type() tmp := a.addNodes(tx, "SetFinalizer.tmp") a.typeAssert(tx, tmp, c.x, false) // Call f(tmp). a.store(f, tmp, 1, a.sizeof(tx)) // Add dynamic call target. if a.onlineCopy(c.targets, f) { a.addWork(c.targets) } } } func ext۰runtime۰SetFinalizer(a *analysis, cgn *cgnode) { // This is the shared contour, used for dynamic calls. targets := a.addOneNode(tInvalid, "SetFinalizer.targets", nil) cgn.sites = append(cgn.sites, &callsite{targets: targets}) params := a.funcParams(cgn.obj) a.addConstraint(&runtimeSetFinalizerConstraint{ targets: targets, x: params, f: params + 1, }) } // ---------- func time.startTimer(t *runtimeTimer) ---------- // time.StartTimer(t) type timeStartTimerConstraint struct { targets nodeid // (indirect) t nodeid // (ptr) } func (c *timeStartTimerConstraint) ptr() nodeid { return c.t } func (c *timeStartTimerConstraint) presolve(h *hvn) { h.markIndirect(onodeid(c.targets), "StartTimer.targets") } func (c *timeStartTimerConstraint) renumber(mapping []nodeid) { c.targets = mapping[c.targets] c.t = mapping[c.t] } func (c *timeStartTimerConstraint) String() string { return fmt.Sprintf("time.startTimer(n%d)", c.t) } func (c *timeStartTimerConstraint) solve(a *analysis, delta *nodeset) { for _, tObj := range delta.AppendTo(a.deltaSpace) { t := nodeid(tObj) // We model startTimer as if it was defined thus: // func startTimer(t *runtimeTimer) { t.f(t.arg) } // We hard-code the field offsets of time.runtimeTimer: // type runtimeTimer struct { // 0 __identity__ // 1 i int32 // 2 when int64 // 3 period int64 // 4 f func(int64, interface{}) // 5 arg interface{} // } f := t + 4 arg := t + 5 // store t.arg to t.f.params[0] // (offset 1 => skip identity) a.store(f, arg, 1, 1) // Add dynamic call target. if a.onlineCopy(c.targets, f) { a.addWork(c.targets) } } } func ext۰time۰startTimer(a *analysis, cgn *cgnode) { // This is the shared contour, used for dynamic calls. targets := a.addOneNode(tInvalid, "startTimer.targets", nil) cgn.sites = append(cgn.sites, &callsite{targets: targets}) params := a.funcParams(cgn.obj) a.addConstraint(&timeStartTimerConstraint{ targets: targets, t: params, }) }