--- /dev/null
+// 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,
+ })
+}
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