| // Copyright 2012 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 gc |
| |
| import ( |
| "fmt" |
| "strings" |
| ) |
| |
| // The racewalk pass modifies the code tree for the function as follows: |
| // |
| // 1. It inserts a call to racefuncenter at the beginning of each function. |
| // 2. It inserts a call to racefuncexit at the end of each function. |
| // 3. It inserts a call to raceread before each memory read. |
| // 4. It inserts a call to racewrite before each memory write. |
| // |
| // The rewriting is not yet complete. Certain nodes are not rewritten |
| // but should be. |
| |
| // TODO(dvyukov): do not instrument initialization as writes: |
| // a := make([]int, 10) |
| |
| // Do not instrument the following packages at all, |
| // at best instrumentation would cause infinite recursion. |
| var omit_pkgs = []string{"runtime", "runtime/race"} |
| |
| // Only insert racefuncenter/racefuncexit into the following packages. |
| // Memory accesses in the packages are either uninteresting or will cause false positives. |
| var noinst_pkgs = []string{"sync", "sync/atomic"} |
| |
| func ispkgin(pkgs []string) bool { |
| if myimportpath != "" { |
| for i := 0; i < len(pkgs); i++ { |
| if myimportpath == pkgs[i] { |
| return true |
| } |
| } |
| } |
| |
| return false |
| } |
| |
| func isforkfunc(fn *Node) bool { |
| // Special case for syscall.forkAndExecInChild. |
| // In the child, this function must not acquire any locks, because |
| // they might have been locked at the time of the fork. This means |
| // no rescheduling, no malloc calls, and no new stack segments. |
| // Race instrumentation does all of the above. |
| return myimportpath != "" && myimportpath == "syscall" && fn.Nname.Sym.Name == "forkAndExecInChild" |
| } |
| |
| func racewalk(fn *Node) { |
| if ispkgin(omit_pkgs) || isforkfunc(fn) { |
| return |
| } |
| |
| if !ispkgin(noinst_pkgs) { |
| racewalklist(fn.Nbody, nil) |
| |
| // nothing interesting for race detector in fn->enter |
| racewalklist(fn.Exit, nil) |
| } |
| |
| // nodpc is the PC of the caller as extracted by |
| // getcallerpc. We use -widthptr(FP) for x86. |
| // BUG: this will not work on arm. |
| nodpc := Nod(OXXX, nil, nil) |
| |
| *nodpc = *nodfp |
| nodpc.Type = Types[TUINTPTR] |
| nodpc.Xoffset = int64(-Widthptr) |
| nd := mkcall("racefuncenter", nil, nil, nodpc) |
| fn.Enter = concat(list1(nd), fn.Enter) |
| nd = mkcall("racefuncexit", nil, nil) |
| fn.Exit = list(fn.Exit, nd) |
| |
| if Debug['W'] != 0 { |
| s := fmt.Sprintf("after racewalk %v", Sconv(fn.Nname.Sym, 0)) |
| dumplist(s, fn.Nbody) |
| s = fmt.Sprintf("enter %v", Sconv(fn.Nname.Sym, 0)) |
| dumplist(s, fn.Enter) |
| s = fmt.Sprintf("exit %v", Sconv(fn.Nname.Sym, 0)) |
| dumplist(s, fn.Exit) |
| } |
| } |
| |
| func racewalklist(l *NodeList, init **NodeList) { |
| var instr *NodeList |
| |
| for ; l != nil; l = l.Next { |
| instr = nil |
| racewalknode(&l.N, &instr, 0, 0) |
| if init == nil { |
| l.N.Ninit = concat(l.N.Ninit, instr) |
| } else { |
| *init = concat(*init, instr) |
| } |
| } |
| } |
| |
| // walkexpr and walkstmt combined |
| // walks the tree and adds calls to the |
| // instrumentation code to top-level (statement) nodes' init |
| func racewalknode(np **Node, init **NodeList, wr int, skip int) { |
| n := *np |
| |
| if n == nil { |
| return |
| } |
| |
| if Debug['w'] > 1 { |
| Dump("racewalk-before", n) |
| } |
| setlineno(n) |
| if init == nil { |
| Fatal("racewalk: bad init list") |
| } |
| if init == &n.Ninit { |
| // If init == &n->ninit and n->ninit is non-nil, |
| // racewalknode might append it to itself. |
| // nil it out and handle it separately before putting it back. |
| l := n.Ninit |
| |
| n.Ninit = nil |
| racewalklist(l, nil) |
| racewalknode(&n, &l, wr, skip) // recurse with nil n->ninit |
| appendinit(&n, l) |
| *np = n |
| return |
| } |
| |
| racewalklist(n.Ninit, nil) |
| |
| switch n.Op { |
| default: |
| Fatal("racewalk: unknown node type %v", Oconv(int(n.Op), 0)) |
| |
| case OAS, |
| OAS2FUNC: |
| racewalknode(&n.Left, init, 1, 0) |
| racewalknode(&n.Right, init, 0, 0) |
| goto ret |
| |
| // can't matter |
| case OCFUNC, |
| OVARKILL: |
| goto ret |
| |
| case OBLOCK: |
| if n.List == nil { |
| goto ret |
| } |
| |
| switch n.List.N.Op { |
| // Blocks are used for multiple return function calls. |
| // x, y := f() becomes BLOCK{CALL f, AS x [SP+0], AS y [SP+n]} |
| // We don't want to instrument between the statements because it will |
| // smash the results. |
| case OCALLFUNC, |
| OCALLMETH, |
| OCALLINTER: |
| racewalknode(&n.List.N, &n.List.N.Ninit, 0, 0) |
| |
| fini := (*NodeList)(nil) |
| racewalklist(n.List.Next, &fini) |
| n.List = concat(n.List, fini) |
| |
| // Ordinary block, for loop initialization or inlined bodies. |
| default: |
| racewalklist(n.List, nil) |
| } |
| |
| goto ret |
| |
| case ODEFER: |
| racewalknode(&n.Left, init, 0, 0) |
| goto ret |
| |
| case OPROC: |
| racewalknode(&n.Left, init, 0, 0) |
| goto ret |
| |
| case OCALLINTER: |
| racewalknode(&n.Left, init, 0, 0) |
| goto ret |
| |
| // Instrument dst argument of runtime.writebarrier* calls |
| // as we do not instrument runtime code. |
| // typedslicecopy is instrumented in runtime. |
| case OCALLFUNC: |
| if n.Left.Sym != nil && n.Left.Sym.Pkg == Runtimepkg && (strings.HasPrefix(n.Left.Sym.Name, "writebarrier") || n.Left.Sym.Name == "typedmemmove") { |
| // Find the dst argument. |
| // The list can be reordered, so it's not necessary just the first or the second element. |
| var l *NodeList |
| for l = n.List; l != nil; l = l.Next { |
| if n.Left.Sym.Name == "typedmemmove" { |
| if l.N.Left.Xoffset == int64(Widthptr) { |
| break |
| } |
| } else { |
| if l.N.Left.Xoffset == 0 { |
| break |
| } |
| } |
| } |
| |
| if l == nil { |
| Fatal("racewalk: writebarrier no arg") |
| } |
| if l.N.Right.Op != OADDR { |
| Fatal("racewalk: writebarrier bad arg") |
| } |
| callinstr(&l.N.Right.Left, init, 1, 0) |
| } |
| |
| racewalknode(&n.Left, init, 0, 0) |
| goto ret |
| |
| case ONOT, |
| OMINUS, |
| OPLUS, |
| OREAL, |
| OIMAG, |
| OCOM: |
| racewalknode(&n.Left, init, wr, 0) |
| goto ret |
| |
| case ODOTINTER: |
| racewalknode(&n.Left, init, 0, 0) |
| goto ret |
| |
| case ODOT: |
| racewalknode(&n.Left, init, 0, 1) |
| callinstr(&n, init, wr, skip) |
| goto ret |
| |
| case ODOTPTR: // dst = (*x).f with implicit *; otherwise it's ODOT+OIND |
| racewalknode(&n.Left, init, 0, 0) |
| |
| callinstr(&n, init, wr, skip) |
| goto ret |
| |
| case OIND: // *p |
| racewalknode(&n.Left, init, 0, 0) |
| |
| callinstr(&n, init, wr, skip) |
| goto ret |
| |
| case OSPTR, |
| OLEN, |
| OCAP: |
| racewalknode(&n.Left, init, 0, 0) |
| if Istype(n.Left.Type, TMAP) { |
| n1 := Nod(OCONVNOP, n.Left, nil) |
| n1.Type = Ptrto(Types[TUINT8]) |
| n1 = Nod(OIND, n1, nil) |
| typecheck(&n1, Erv) |
| callinstr(&n1, init, 0, skip) |
| } |
| |
| goto ret |
| |
| case OLSH, |
| ORSH, |
| OLROT, |
| OAND, |
| OANDNOT, |
| OOR, |
| OXOR, |
| OSUB, |
| OMUL, |
| OHMUL, |
| OEQ, |
| ONE, |
| OLT, |
| OLE, |
| OGE, |
| OGT, |
| OADD, |
| OCOMPLEX: |
| racewalknode(&n.Left, init, wr, 0) |
| racewalknode(&n.Right, init, wr, 0) |
| goto ret |
| |
| case OANDAND, |
| OOROR: |
| racewalknode(&n.Left, init, wr, 0) |
| |
| // walk has ensured the node has moved to a location where |
| // side effects are safe. |
| // n->right may not be executed, |
| // so instrumentation goes to n->right->ninit, not init. |
| racewalknode(&n.Right, &n.Right.Ninit, wr, 0) |
| |
| goto ret |
| |
| case ONAME: |
| callinstr(&n, init, wr, skip) |
| goto ret |
| |
| case OCONV: |
| racewalknode(&n.Left, init, wr, 0) |
| goto ret |
| |
| case OCONVNOP: |
| racewalknode(&n.Left, init, wr, 0) |
| goto ret |
| |
| case ODIV, |
| OMOD: |
| racewalknode(&n.Left, init, wr, 0) |
| racewalknode(&n.Right, init, wr, 0) |
| goto ret |
| |
| case OINDEX: |
| if !Isfixedarray(n.Left.Type) { |
| racewalknode(&n.Left, init, 0, 0) |
| } else if !islvalue(n.Left) { |
| // index of unaddressable array, like Map[k][i]. |
| racewalknode(&n.Left, init, wr, 0) |
| |
| racewalknode(&n.Right, init, 0, 0) |
| goto ret |
| } |
| |
| racewalknode(&n.Right, init, 0, 0) |
| if n.Left.Type.Etype != TSTRING { |
| callinstr(&n, init, wr, skip) |
| } |
| goto ret |
| |
| // Seems to only lead to double instrumentation. |
| //racewalknode(&n->left, init, 0, 0); |
| case OSLICE, |
| OSLICEARR, |
| OSLICE3, |
| OSLICE3ARR: |
| goto ret |
| |
| case OADDR: |
| racewalknode(&n.Left, init, 0, 1) |
| goto ret |
| |
| // n->left is Type* which is not interesting. |
| case OEFACE: |
| racewalknode(&n.Right, init, 0, 0) |
| |
| goto ret |
| |
| case OITAB: |
| racewalknode(&n.Left, init, 0, 0) |
| goto ret |
| |
| // should not appear in AST by now |
| case OSEND, |
| ORECV, |
| OCLOSE, |
| ONEW, |
| OXCASE, |
| OXFALL, |
| OCASE, |
| OPANIC, |
| ORECOVER, |
| OCONVIFACE, |
| OCMPIFACE, |
| OMAKECHAN, |
| OMAKEMAP, |
| OMAKESLICE, |
| OCALL, |
| OCOPY, |
| OAPPEND, |
| ORUNESTR, |
| OARRAYBYTESTR, |
| OARRAYRUNESTR, |
| OSTRARRAYBYTE, |
| OSTRARRAYRUNE, |
| OINDEXMAP, |
| // lowered to call |
| OCMPSTR, |
| OADDSTR, |
| ODOTTYPE, |
| ODOTTYPE2, |
| OAS2DOTTYPE, |
| OCALLPART, |
| // lowered to PTRLIT |
| OCLOSURE, // lowered to PTRLIT |
| ORANGE, // lowered to ordinary for loop |
| OARRAYLIT, // lowered to assignments |
| OMAPLIT, |
| OSTRUCTLIT, |
| OAS2, |
| OAS2RECV, |
| OAS2MAPR, |
| OASOP: |
| Yyerror("racewalk: %v must be lowered by now", Oconv(int(n.Op), 0)) |
| |
| goto ret |
| |
| // impossible nodes: only appear in backend. |
| case ORROTC, |
| OEXTEND: |
| Yyerror("racewalk: %v cannot exist now", Oconv(int(n.Op), 0)) |
| |
| goto ret |
| |
| // just do generic traversal |
| case OFOR, |
| OIF, |
| OCALLMETH, |
| ORETURN, |
| ORETJMP, |
| OSWITCH, |
| OSELECT, |
| OEMPTY, |
| OBREAK, |
| OCONTINUE, |
| OFALL, |
| OGOTO, |
| OLABEL: |
| goto ret |
| |
| // does not require instrumentation |
| case OPRINT, // don't bother instrumenting it |
| OPRINTN, // don't bother instrumenting it |
| OCHECKNIL, // always followed by a read. |
| OPARAM, // it appears only in fn->exit to copy heap params back |
| OCLOSUREVAR, // immutable pointer to captured variable |
| ODOTMETH, // either part of CALLMETH or CALLPART (lowered to PTRLIT) |
| OINDREG, // at this stage, only n(SP) nodes from nodarg |
| ODCL, // declarations (without value) cannot be races |
| ODCLCONST, |
| ODCLTYPE, |
| OTYPE, |
| ONONAME, |
| OLITERAL, |
| OSLICESTR, |
| // always preceded by bounds checking, avoid double instrumentation. |
| OTYPESW: // ignored by code generation, do not instrument. |
| goto ret |
| } |
| |
| ret: |
| if n.Op != OBLOCK { // OBLOCK is handled above in a special way. |
| racewalklist(n.List, init) |
| } |
| if n.Ntest != nil { |
| racewalknode(&n.Ntest, &n.Ntest.Ninit, 0, 0) |
| } |
| if n.Nincr != nil { |
| racewalknode(&n.Nincr, &n.Nincr.Ninit, 0, 0) |
| } |
| racewalklist(n.Nbody, nil) |
| racewalklist(n.Nelse, nil) |
| racewalklist(n.Rlist, nil) |
| *np = n |
| } |
| |
| func isartificial(n *Node) bool { |
| // compiler-emitted artificial things that we do not want to instrument, |
| // cant' possibly participate in a data race. |
| if n.Op == ONAME && n.Sym != nil && n.Sym.Name != "" { |
| if n.Sym.Name == "_" { |
| return true |
| } |
| |
| // autotmp's are always local |
| if strings.HasPrefix(n.Sym.Name, "autotmp_") { |
| return true |
| } |
| |
| // statictmp's are read-only |
| if strings.HasPrefix(n.Sym.Name, "statictmp_") { |
| return true |
| } |
| |
| // go.itab is accessed only by the compiler and runtime (assume safe) |
| if n.Sym.Pkg != nil && n.Sym.Pkg.Name != "" && n.Sym.Pkg.Name == "go.itab" { |
| return true |
| } |
| } |
| |
| return false |
| } |
| |
| func callinstr(np **Node, init **NodeList, wr int, skip int) bool { |
| n := *np |
| |
| //print("callinstr for %+N [ %O ] etype=%E class=%d\n", |
| // n, n->op, n->type ? n->type->etype : -1, n->class); |
| |
| if skip != 0 || n.Type == nil || n.Type.Etype >= TIDEAL { |
| return false |
| } |
| t := n.Type |
| if isartificial(n) { |
| return false |
| } |
| |
| b := outervalue(n) |
| |
| // it skips e.g. stores to ... parameter array |
| if isartificial(b) { |
| return false |
| } |
| class := int(b.Class) |
| |
| // BUG: we _may_ want to instrument PAUTO sometimes |
| // e.g. if we've got a local variable/method receiver |
| // that has got a pointer inside. Whether it points to |
| // the heap or not is impossible to know at compile time |
| if (class&PHEAP != 0) || class == PPARAMREF || class == PEXTERN || b.Op == OINDEX || b.Op == ODOTPTR || b.Op == OIND { |
| hascalls := 0 |
| foreach(n, hascallspred, &hascalls) |
| if hascalls != 0 { |
| n = detachexpr(n, init) |
| *np = n |
| } |
| |
| n = treecopy(n) |
| makeaddable(n) |
| var f *Node |
| if t.Etype == TSTRUCT || Isfixedarray(t) { |
| name := "racereadrange" |
| if wr != 0 { |
| name = "racewriterange" |
| } |
| f = mkcall(name, nil, init, uintptraddr(n), Nodintconst(t.Width)) |
| } else { |
| name := "raceread" |
| if wr != 0 { |
| name = "racewrite" |
| } |
| f = mkcall(name, nil, init, uintptraddr(n)) |
| } |
| |
| *init = list(*init, f) |
| return true |
| } |
| |
| return false |
| } |
| |
| // makeaddable returns a node whose memory location is the |
| // same as n, but which is addressable in the Go language |
| // sense. |
| // This is different from functions like cheapexpr that may make |
| // a copy of their argument. |
| func makeaddable(n *Node) { |
| // The arguments to uintptraddr technically have an address but |
| // may not be addressable in the Go sense: for example, in the case |
| // of T(v).Field where T is a struct type and v is |
| // an addressable value. |
| switch n.Op { |
| case OINDEX: |
| if Isfixedarray(n.Left.Type) { |
| makeaddable(n.Left) |
| } |
| |
| // Turn T(v).Field into v.Field |
| case ODOT, |
| OXDOT: |
| if n.Left.Op == OCONVNOP { |
| n.Left = n.Left.Left |
| } |
| makeaddable(n.Left) |
| |
| // nothing to do |
| case ODOTPTR: |
| fallthrough |
| default: |
| break |
| } |
| } |
| |
| func uintptraddr(n *Node) *Node { |
| r := Nod(OADDR, n, nil) |
| r.Bounded = true |
| r = conv(r, Types[TUNSAFEPTR]) |
| r = conv(r, Types[TUINTPTR]) |
| return r |
| } |
| |
| func detachexpr(n *Node, init **NodeList) *Node { |
| addr := Nod(OADDR, n, nil) |
| l := temp(Ptrto(n.Type)) |
| as := Nod(OAS, l, addr) |
| typecheck(&as, Etop) |
| walkexpr(&as, init) |
| *init = list(*init, as) |
| ind := Nod(OIND, l, nil) |
| typecheck(&ind, Erv) |
| walkexpr(&ind, init) |
| return ind |
| } |
| |
| func foreachnode(n *Node, f func(*Node, interface{}), c interface{}) { |
| if n != nil { |
| f(n, c) |
| } |
| } |
| |
| func foreachlist(l *NodeList, f func(*Node, interface{}), c interface{}) { |
| for ; l != nil; l = l.Next { |
| foreachnode(l.N, f, c) |
| } |
| } |
| |
| func foreach(n *Node, f func(*Node, interface{}), c interface{}) { |
| foreachlist(n.Ninit, f, c) |
| foreachnode(n.Left, f, c) |
| foreachnode(n.Right, f, c) |
| foreachlist(n.List, f, c) |
| foreachnode(n.Ntest, f, c) |
| foreachnode(n.Nincr, f, c) |
| foreachlist(n.Nbody, f, c) |
| foreachlist(n.Nelse, f, c) |
| foreachlist(n.Rlist, f, c) |
| } |
| |
| func hascallspred(n *Node, c interface{}) { |
| switch n.Op { |
| case OCALL, |
| OCALLFUNC, |
| OCALLMETH, |
| OCALLINTER: |
| (*c.(*int))++ |
| } |
| } |
| |
| // appendinit is like addinit in subr.c |
| // but appends rather than prepends. |
| func appendinit(np **Node, init *NodeList) { |
| if init == nil { |
| return |
| } |
| |
| n := *np |
| switch n.Op { |
| // There may be multiple refs to this node; |
| // introduce OCONVNOP to hold init list. |
| case ONAME, |
| OLITERAL: |
| n = Nod(OCONVNOP, n, nil) |
| |
| n.Type = n.Left.Type |
| n.Typecheck = 1 |
| *np = n |
| } |
| |
| n.Ninit = concat(n.Ninit, init) |
| n.Ullman = UINF |
| } |
