|
|
// 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, })}
|
