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