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// 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"
"code.google.com/p/go.tools/go/ssa"
"code.google.com/p/go.tools/go/types"
)
// 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,
"runtime.BlockProfile": ext۰NoEffect,
"runtime.Breakpoint": ext۰NoEffect,
"runtime.CPUProfile": ext۰NoEffect, // good enough
"runtime.Caller": ext۰NoEffect,
"runtime.Callers": ext۰NoEffect, // good enough
"runtime.FuncForPC": ext۰NoEffect,
"runtime.GC": ext۰NoEffect,
"runtime.GOMAXPROCS": ext۰NoEffect,
"runtime.Goexit": ext۰NoEffect,
"runtime.GoroutineProfile": ext۰NoEffect,
"runtime.Gosched": ext۰NoEffect,
"runtime.MemProfile": ext۰NoEffect,
"runtime.NumCPU": ext۰NoEffect,
"runtime.NumGoroutine": ext۰NoEffect,
"runtime.ReadMemStats": ext۰NoEffect,
"runtime.SetBlockProfileRate": ext۰NoEffect,
"runtime.SetCPUProfileRate": ext۰NoEffect,
"runtime.SetFinalizer": ext۰runtime۰SetFinalizer,
"runtime.Stack": ext۰NoEffect,
"runtime.ThreadCreateProfile": ext۰NoEffect,
"runtime.cstringToGo": ext۰NoEffect,
"runtime.funcentry_go": ext۰NoEffect,
"runtime.funcline_go": ext۰NoEffect,
"runtime.funcname_go": ext۰NoEffect,
"runtime.getgoroot": ext۰NoEffect,
"runtime/pprof.runtime_cyclesPerSecond": ext۰NoEffect,
"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.Pointer for now
"sync/atomic.LoadUint32": ext۰NoEffect,
"sync/atomic.LoadUint64": ext۰NoEffect,
"sync/atomic.LoadUintptr": ext۰NoEffect,
"sync/atomic.StoreInt32": ext۰NoEffect,
"sync/atomic.StorePointer": ext۰NoEffect, // ignore unsafe.Pointer for now
"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": ext۰NoEffect,
"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
}
}
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.Object == 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) {
// TODO(adonovan): enable this warning when we've implemented
// enough that it's not unbearably annoying.
if true {
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
f nodeid // (ptr)
x nodeid
}
func (c *runtimeSetFinalizerConstraint) ptr() nodeid { return c.f }
func (c *runtimeSetFinalizerConstraint) indirect(nodes []nodeid) []nodeid { return nodes }
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, _ *node, delta nodeset) {
for fObj := range delta {
tDyn, f, indirect := a.taggedValue(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,
})
}
|
