From b1247d2d0d51108c910a73891ff3116e5f032ab1 Mon Sep 17 00:00:00 2001 From: "Kali Kaneko (leap communications)" Date: Sat, 12 Jan 2019 18:39:45 +0100 Subject: [pkg] all your deps are vendored to us --- vendor/golang.org/x/tools/go/ssa/wrappers.go | 294 +++++++++++++++++++++++++++ 1 file changed, 294 insertions(+) create mode 100644 vendor/golang.org/x/tools/go/ssa/wrappers.go (limited to 'vendor/golang.org/x/tools/go/ssa/wrappers.go') diff --git a/vendor/golang.org/x/tools/go/ssa/wrappers.go b/vendor/golang.org/x/tools/go/ssa/wrappers.go new file mode 100644 index 0000000..701dd90 --- /dev/null +++ b/vendor/golang.org/x/tools/go/ssa/wrappers.go @@ -0,0 +1,294 @@ +// 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 ssa + +// This file defines synthesis of Functions that delegate to declared +// methods; they come in three kinds: +// +// (1) wrappers: methods that wrap declared methods, performing +// implicit pointer indirections and embedded field selections. +// +// (2) thunks: funcs that wrap declared methods. Like wrappers, +// thunks perform indirections and field selections. The thunk's +// first parameter is used as the receiver for the method call. +// +// (3) bounds: funcs that wrap declared methods. The bound's sole +// free variable, supplied by a closure, is used as the receiver +// for the method call. No indirections or field selections are +// performed since they can be done before the call. + +import ( + "fmt" + + "go/types" +) + +// -- wrappers ----------------------------------------------------------- + +// makeWrapper returns a synthetic method that delegates to the +// declared method denoted by meth.Obj(), first performing any +// necessary pointer indirections or field selections implied by meth. +// +// The resulting method's receiver type is meth.Recv(). +// +// This function is versatile but quite subtle! Consider the +// following axes of variation when making changes: +// - optional receiver indirection +// - optional implicit field selections +// - meth.Obj() may denote a concrete or an interface method +// - the result may be a thunk or a wrapper. +// +// EXCLUSIVE_LOCKS_REQUIRED(prog.methodsMu) +// +func makeWrapper(prog *Program, sel *types.Selection) *Function { + obj := sel.Obj().(*types.Func) // the declared function + sig := sel.Type().(*types.Signature) // type of this wrapper + + var recv *types.Var // wrapper's receiver or thunk's params[0] + name := obj.Name() + var description string + var start int // first regular param + if sel.Kind() == types.MethodExpr { + name += "$thunk" + description = "thunk" + recv = sig.Params().At(0) + start = 1 + } else { + description = "wrapper" + recv = sig.Recv() + } + + description = fmt.Sprintf("%s for %s", description, sel.Obj()) + if prog.mode&LogSource != 0 { + defer logStack("make %s to (%s)", description, recv.Type())() + } + fn := &Function{ + name: name, + method: sel, + object: obj, + Signature: sig, + Synthetic: description, + Prog: prog, + pos: obj.Pos(), + } + fn.startBody() + fn.addSpilledParam(recv) + createParams(fn, start) + + indices := sel.Index() + + var v Value = fn.Locals[0] // spilled receiver + if isPointer(sel.Recv()) { + v = emitLoad(fn, v) + + // For simple indirection wrappers, perform an informative nil-check: + // "value method (T).f called using nil *T pointer" + if len(indices) == 1 && !isPointer(recvType(obj)) { + var c Call + c.Call.Value = &Builtin{ + name: "ssa:wrapnilchk", + sig: types.NewSignature(nil, + types.NewTuple(anonVar(sel.Recv()), anonVar(tString), anonVar(tString)), + types.NewTuple(anonVar(sel.Recv())), false), + } + c.Call.Args = []Value{ + v, + stringConst(deref(sel.Recv()).String()), + stringConst(sel.Obj().Name()), + } + c.setType(v.Type()) + v = fn.emit(&c) + } + } + + // Invariant: v is a pointer, either + // value of *A receiver param, or + // address of A spilled receiver. + + // We use pointer arithmetic (FieldAddr possibly followed by + // Load) in preference to value extraction (Field possibly + // preceded by Load). + + v = emitImplicitSelections(fn, v, indices[:len(indices)-1]) + + // Invariant: v is a pointer, either + // value of implicit *C field, or + // address of implicit C field. + + var c Call + if r := recvType(obj); !isInterface(r) { // concrete method + if !isPointer(r) { + v = emitLoad(fn, v) + } + c.Call.Value = prog.declaredFunc(obj) + c.Call.Args = append(c.Call.Args, v) + } else { + c.Call.Method = obj + c.Call.Value = emitLoad(fn, v) + } + for _, arg := range fn.Params[1:] { + c.Call.Args = append(c.Call.Args, arg) + } + emitTailCall(fn, &c) + fn.finishBody() + return fn +} + +// createParams creates parameters for wrapper method fn based on its +// Signature.Params, which do not include the receiver. +// start is the index of the first regular parameter to use. +// +func createParams(fn *Function, start int) { + var last *Parameter + tparams := fn.Signature.Params() + for i, n := start, tparams.Len(); i < n; i++ { + last = fn.addParamObj(tparams.At(i)) + } + if fn.Signature.Variadic() { + last.typ = types.NewSlice(last.typ) + } +} + +// -- bounds ----------------------------------------------------------- + +// makeBound returns a bound method wrapper (or "bound"), a synthetic +// function that delegates to a concrete or interface method denoted +// by obj. The resulting function has no receiver, but has one free +// variable which will be used as the method's receiver in the +// tail-call. +// +// Use MakeClosure with such a wrapper to construct a bound method +// closure. e.g.: +// +// type T int or: type T interface { meth() } +// func (t T) meth() +// var t T +// f := t.meth +// f() // calls t.meth() +// +// f is a closure of a synthetic wrapper defined as if by: +// +// f := func() { return t.meth() } +// +// Unlike makeWrapper, makeBound need perform no indirection or field +// selections because that can be done before the closure is +// constructed. +// +// EXCLUSIVE_LOCKS_ACQUIRED(meth.Prog.methodsMu) +// +func makeBound(prog *Program, obj *types.Func) *Function { + prog.methodsMu.Lock() + defer prog.methodsMu.Unlock() + fn, ok := prog.bounds[obj] + if !ok { + description := fmt.Sprintf("bound method wrapper for %s", obj) + if prog.mode&LogSource != 0 { + defer logStack("%s", description)() + } + fn = &Function{ + name: obj.Name() + "$bound", + object: obj, + Signature: changeRecv(obj.Type().(*types.Signature), nil), // drop receiver + Synthetic: description, + Prog: prog, + pos: obj.Pos(), + } + + fv := &FreeVar{name: "recv", typ: recvType(obj), parent: fn} + fn.FreeVars = []*FreeVar{fv} + fn.startBody() + createParams(fn, 0) + var c Call + + if !isInterface(recvType(obj)) { // concrete + c.Call.Value = prog.declaredFunc(obj) + c.Call.Args = []Value{fv} + } else { + c.Call.Value = fv + c.Call.Method = obj + } + for _, arg := range fn.Params { + c.Call.Args = append(c.Call.Args, arg) + } + emitTailCall(fn, &c) + fn.finishBody() + + prog.bounds[obj] = fn + } + return fn +} + +// -- thunks ----------------------------------------------------------- + +// makeThunk returns a thunk, a synthetic function that delegates to a +// concrete or interface method denoted by sel.Obj(). The resulting +// function has no receiver, but has an additional (first) regular +// parameter. +// +// Precondition: sel.Kind() == types.MethodExpr. +// +// type T int or: type T interface { meth() } +// func (t T) meth() +// f := T.meth +// var t T +// f(t) // calls t.meth() +// +// f is a synthetic wrapper defined as if by: +// +// f := func(t T) { return t.meth() } +// +// TODO(adonovan): opt: currently the stub is created even when used +// directly in a function call: C.f(i, 0). This is less efficient +// than inlining the stub. +// +// EXCLUSIVE_LOCKS_ACQUIRED(meth.Prog.methodsMu) +// +func makeThunk(prog *Program, sel *types.Selection) *Function { + if sel.Kind() != types.MethodExpr { + panic(sel) + } + + key := selectionKey{ + kind: sel.Kind(), + recv: sel.Recv(), + obj: sel.Obj(), + index: fmt.Sprint(sel.Index()), + indirect: sel.Indirect(), + } + + prog.methodsMu.Lock() + defer prog.methodsMu.Unlock() + + // Canonicalize key.recv to avoid constructing duplicate thunks. + canonRecv, ok := prog.canon.At(key.recv).(types.Type) + if !ok { + canonRecv = key.recv + prog.canon.Set(key.recv, canonRecv) + } + key.recv = canonRecv + + fn, ok := prog.thunks[key] + if !ok { + fn = makeWrapper(prog, sel) + if fn.Signature.Recv() != nil { + panic(fn) // unexpected receiver + } + prog.thunks[key] = fn + } + return fn +} + +func changeRecv(s *types.Signature, recv *types.Var) *types.Signature { + return types.NewSignature(recv, s.Params(), s.Results(), s.Variadic()) +} + +// selectionKey is like types.Selection but a usable map key. +type selectionKey struct { + kind types.SelectionKind + recv types.Type // canonicalized via Program.canon + obj types.Object + index string + indirect bool +} -- cgit v1.2.3