1 files changed, 458 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/escape/call.go b/src/cmd/compile/internal/escape/call.go
new file mode 100644
index 0000000..ee76adb
--- /dev/null
+++ b/src/cmd/compile/internal/escape/call.go
@@ -0,0 +1,458 @@
+// Copyright 2018 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 escape
+
+import (
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/typecheck"
+	"cmd/compile/internal/types"
+	"cmd/internal/src"
+)
+
+// call evaluates a call expressions, including builtin calls. ks
+// should contain the holes representing where the function callee's
+// results flows.
+func (e *escape) call(ks []hole, call ir.Node) {
+	var init ir.Nodes
+	e.callCommon(ks, call, &init, nil)
+	if len(init) != 0 {
+		call.(*ir.CallExpr).PtrInit().Append(init...)
+	}
+}
+
+func (e *escape) callCommon(ks []hole, call ir.Node, init *ir.Nodes, wrapper *ir.Func) {
+
+	// argumentPragma handles escape analysis of argument *argp to the
+	// given hole. If the function callee is known, pragma is the
+	// function's pragma flags; otherwise 0.
+	argumentFunc := func(fn *ir.Name, k hole, argp *ir.Node) {
+		e.rewriteArgument(argp, init, call, fn, wrapper)
+
+		e.expr(k.note(call, "call parameter"), *argp)
+	}
+
+	argument := func(k hole, argp *ir.Node) {
+		argumentFunc(nil, k, argp)
+	}
+
+	switch call.Op() {
+	default:
+		ir.Dump("esc", call)
+		base.Fatalf("unexpected call op: %v", call.Op())
+
+	case ir.OCALLFUNC, ir.OCALLMETH, ir.OCALLINTER:
+		call := call.(*ir.CallExpr)
+		typecheck.FixVariadicCall(call)
+		typecheck.FixMethodCall(call)
+
+		// Pick out the function callee, if statically known.
+		//
+		// TODO(mdempsky): Change fn from *ir.Name to *ir.Func, but some
+		// functions (e.g., runtime builtins, method wrappers, generated
+		// eq/hash functions) don't have it set. Investigate whether
+		// that's a concern.
+		var fn *ir.Name
+		switch call.Op() {
+		case ir.OCALLFUNC:
+			// If we have a direct call to a closure (not just one we were
+			// able to statically resolve with ir.StaticValue), mark it as
+			// such so batch.outlives can optimize the flow results.
+			if call.X.Op() == ir.OCLOSURE {
+				call.X.(*ir.ClosureExpr).Func.SetClosureCalled(true)
+			}
+
+			switch v := ir.StaticValue(call.X); v.Op() {
+			case ir.ONAME:
+				if v := v.(*ir.Name); v.Class == ir.PFUNC {
+					fn = v
+				}
+			case ir.OCLOSURE:
+				fn = v.(*ir.ClosureExpr).Func.Nname
+			case ir.OMETHEXPR:
+				fn = ir.MethodExprName(v)
+			}
+		case ir.OCALLMETH:
+			base.FatalfAt(call.Pos(), "OCALLMETH missed by typecheck")
+		}
+
+		fntype := call.X.Type()
+		if fn != nil {
+			fntype = fn.Type()
+		}
+
+		if ks != nil && fn != nil && e.inMutualBatch(fn) {
+			for i, result := range fn.Type().Results().FieldSlice() {
+				e.expr(ks[i], ir.AsNode(result.Nname))
+			}
+		}
+
+		var recvp *ir.Node
+		if call.Op() == ir.OCALLFUNC {
+			// Evaluate callee function expression.
+			//
+			// Note: We use argument and not argumentFunc, because while
+			// call.X here may be an argument to runtime.{new,defer}proc,
+			// it's not an argument to fn itself.
+			argument(e.discardHole(), &call.X)
+		} else {
+			recvp = &call.X.(*ir.SelectorExpr).X
+		}
+
+		args := call.Args
+		if recv := fntype.Recv(); recv != nil {
+			if recvp == nil {
+				// Function call using method expression. Recevier argument is
+				// at the front of the regular arguments list.
+				recvp = &args[0]
+				args = args[1:]
+			}
+
+			argumentFunc(fn, e.tagHole(ks, fn, recv), recvp)
+		}
+
+		for i, param := range fntype.Params().FieldSlice() {
+			argumentFunc(fn, e.tagHole(ks, fn, param), &args[i])
+		}
+
+	case ir.OINLCALL:
+		call := call.(*ir.InlinedCallExpr)
+		e.stmts(call.Body)
+		for i, result := range call.ReturnVars {
+			k := e.discardHole()
+			if ks != nil {
+				k = ks[i]
+			}
+			e.expr(k, result)
+		}
+
+	case ir.OAPPEND:
+		call := call.(*ir.CallExpr)
+		args := call.Args
+
+		// Appendee slice may flow directly to the result, if
+		// it has enough capacity. Alternatively, a new heap
+		// slice might be allocated, and all slice elements
+		// might flow to heap.
+		appendeeK := ks[0]
+		if args[0].Type().Elem().HasPointers() {
+			appendeeK = e.teeHole(appendeeK, e.heapHole().deref(call, "appendee slice"))
+		}
+		argument(appendeeK, &args[0])
+
+		if call.IsDDD {
+			appendedK := e.discardHole()
+			if args[1].Type().IsSlice() && args[1].Type().Elem().HasPointers() {
+				appendedK = e.heapHole().deref(call, "appended slice...")
+			}
+			argument(appendedK, &args[1])
+		} else {
+			for i := 1; i < len(args); i++ {
+				argument(e.heapHole(), &args[i])
+			}
+		}
+
+	case ir.OCOPY:
+		call := call.(*ir.BinaryExpr)
+		argument(e.discardHole(), &call.X)
+
+		copiedK := e.discardHole()
+		if call.Y.Type().IsSlice() && call.Y.Type().Elem().HasPointers() {
+			copiedK = e.heapHole().deref(call, "copied slice")
+		}
+		argument(copiedK, &call.Y)
+
+	case ir.OPANIC:
+		call := call.(*ir.UnaryExpr)
+		argument(e.heapHole(), &call.X)
+
+	case ir.OCOMPLEX:
+		call := call.(*ir.BinaryExpr)
+		argument(e.discardHole(), &call.X)
+		argument(e.discardHole(), &call.Y)
+
+	case ir.ODELETE, ir.OPRINT, ir.OPRINTN, ir.ORECOVER:
+		call := call.(*ir.CallExpr)
+		fixRecoverCall(call)
+		for i := range call.Args {
+			argument(e.discardHole(), &call.Args[i])
+		}
+
+	case ir.OLEN, ir.OCAP, ir.OREAL, ir.OIMAG, ir.OCLOSE:
+		call := call.(*ir.UnaryExpr)
+		argument(e.discardHole(), &call.X)
+
+	case ir.OUNSAFEADD, ir.OUNSAFESLICE:
+		call := call.(*ir.BinaryExpr)
+		argument(ks[0], &call.X)
+		argument(e.discardHole(), &call.Y)
+	}
+}
+
+// goDeferStmt analyzes a "go" or "defer" statement.
+//
+// In the process, it also normalizes the statement to always use a
+// simple function call with no arguments and no results. For example,
+// it rewrites:
+//
+//	defer f(x, y)
+//
+// into:
+//
+//	x1, y1 := x, y
+//	defer func() { f(x1, y1) }()
+func (e *escape) goDeferStmt(n *ir.GoDeferStmt) {
+	k := e.heapHole()
+	if n.Op() == ir.ODEFER && e.loopDepth == 1 {
+		// Top-level defer arguments don't escape to the heap,
+		// but they do need to last until they're invoked.
+		k = e.later(e.discardHole())
+
+		// force stack allocation of defer record, unless
+		// open-coded defers are used (see ssa.go)
+		n.SetEsc(ir.EscNever)
+	}
+
+	call := n.Call
+
+	init := n.PtrInit()
+	init.Append(ir.TakeInit(call)...)
+	e.stmts(*init)
+
+	// If the function is already a zero argument/result function call,
+	// just escape analyze it normally.
+	if call, ok := call.(*ir.CallExpr); ok && call.Op() == ir.OCALLFUNC {
+		if sig := call.X.Type(); sig.NumParams()+sig.NumResults() == 0 {
+			if clo, ok := call.X.(*ir.ClosureExpr); ok && n.Op() == ir.OGO {
+				clo.IsGoWrap = true
+			}
+			e.expr(k, call.X)
+			return
+		}
+	}
+
+	// Create a new no-argument function that we'll hand off to defer.
+	fn := ir.NewClosureFunc(n.Pos(), true)
+	fn.SetWrapper(true)
+	fn.Nname.SetType(types.NewSignature(types.LocalPkg, nil, nil, nil, nil))
+	fn.Body = []ir.Node{call}
+	if call, ok := call.(*ir.CallExpr); ok && call.Op() == ir.OCALLFUNC {
+		// If the callee is a named function, link to the original callee.
+		x := call.X
+		if x.Op() == ir.ONAME && x.(*ir.Name).Class == ir.PFUNC {
+			fn.WrappedFunc = call.X.(*ir.Name).Func
+		} else if x.Op() == ir.OMETHEXPR && ir.MethodExprFunc(x).Nname != nil {
+			fn.WrappedFunc = ir.MethodExprName(x).Func
+		}
+	}
+
+	clo := fn.OClosure
+	if n.Op() == ir.OGO {
+		clo.IsGoWrap = true
+	}
+
+	e.callCommon(nil, call, init, fn)
+	e.closures = append(e.closures, closure{e.spill(k, clo), clo})
+
+	// Create new top level call to closure.
+	n.Call = ir.NewCallExpr(call.Pos(), ir.OCALL, clo, nil)
+	ir.WithFunc(e.curfn, func() {
+		typecheck.Stmt(n.Call)
+	})
+}
+
+// rewriteArgument rewrites the argument *argp of the given call expression.
+// fn is the static callee function, if known.
+// wrapper is the go/defer wrapper function for call, if any.
+func (e *escape) rewriteArgument(argp *ir.Node, init *ir.Nodes, call ir.Node, fn *ir.Name, wrapper *ir.Func) {
+	var pragma ir.PragmaFlag
+	if fn != nil && fn.Func != nil {
+		pragma = fn.Func.Pragma
+	}
+
+	// unsafeUintptr rewrites "uintptr(ptr)" arguments to syscall-like
+	// functions, so that ptr is kept alive and/or escaped as
+	// appropriate. unsafeUintptr also reports whether it modified arg0.
+	unsafeUintptr := func(arg0 ir.Node) bool {
+		if pragma&(ir.UintptrKeepAlive|ir.UintptrEscapes) == 0 {
+			return false
+		}
+
+		// If the argument is really a pointer being converted to uintptr,
+		// arrange for the pointer to be kept alive until the call returns,
+		// by copying it into a temp and marking that temp
+		// still alive when we pop the temp stack.
+		if arg0.Op() != ir.OCONVNOP || !arg0.Type().IsUintptr() {
+			return false
+		}
+		arg := arg0.(*ir.ConvExpr)
+
+		if !arg.X.Type().IsUnsafePtr() {
+			return false
+		}
+
+		// Create and declare a new pointer-typed temp variable.
+		tmp := e.wrapExpr(arg.Pos(), &arg.X, init, call, wrapper)
+
+		if pragma&ir.UintptrEscapes != 0 {
+			e.flow(e.heapHole().note(arg, "//go:uintptrescapes"), e.oldLoc(tmp))
+		}
+
+		if pragma&ir.UintptrKeepAlive != 0 {
+			call := call.(*ir.CallExpr)
+
+			// SSA implements CallExpr.KeepAlive using OpVarLive, which
+			// doesn't support PAUTOHEAP variables. I tried changing it to
+			// use OpKeepAlive, but that ran into issues of its own.
+			// For now, the easy solution is to explicitly copy to (yet
+			// another) new temporary variable.
+			keep := tmp
+			if keep.Class == ir.PAUTOHEAP {
+				keep = e.copyExpr(arg.Pos(), tmp, call.PtrInit(), wrapper, false)
+			}
+
+			keep.SetAddrtaken(true) // ensure SSA keeps the tmp variable
+			call.KeepAlive = append(call.KeepAlive, keep)
+		}
+
+		return true
+	}
+
+	visit := func(pos src.XPos, argp *ir.Node) {
+		// Optimize a few common constant expressions. By leaving these
+		// untouched in the call expression, we let the wrapper handle
+		// evaluating them, rather than taking up closure context space.
+		switch arg := *argp; arg.Op() {
+		case ir.OLITERAL, ir.ONIL, ir.OMETHEXPR:
+			return
+		case ir.ONAME:
+			if arg.(*ir.Name).Class == ir.PFUNC {
+				return
+			}
+		}
+
+		if unsafeUintptr(*argp) {
+			return
+		}
+
+		if wrapper != nil {
+			e.wrapExpr(pos, argp, init, call, wrapper)
+		}
+	}
+
+	// Peel away any slice literals for better escape analyze
+	// them. For example:
+	//
+	//     go F([]int{a, b})
+	//
+	// If F doesn't escape its arguments, then the slice can
+	// be allocated on the new goroutine's stack.
+	//
+	// For variadic functions, the compiler has already rewritten:
+	//
+	//     f(a, b, c)
+	//
+	// to:
+	//
+	//     f([]T{a, b, c}...)
+	//
+	// So we need to look into slice elements to handle uintptr(ptr)
+	// arguments to syscall-like functions correctly.
+	if arg := *argp; arg.Op() == ir.OSLICELIT {
+		list := arg.(*ir.CompLitExpr).List
+		for i := range list {
+			el := &list[i]
+			if list[i].Op() == ir.OKEY {
+				el = &list[i].(*ir.KeyExpr).Value
+			}
+			visit(arg.Pos(), el)
+		}
+	} else {
+		visit(call.Pos(), argp)
+	}
+}
+
+// wrapExpr replaces *exprp with a temporary variable copy. If wrapper
+// is non-nil, the variable will be captured for use within that
+// function.
+func (e *escape) wrapExpr(pos src.XPos, exprp *ir.Node, init *ir.Nodes, call ir.Node, wrapper *ir.Func) *ir.Name {
+	tmp := e.copyExpr(pos, *exprp, init, e.curfn, true)
+
+	if wrapper != nil {
+		// Currently for "defer i.M()" if i is nil it panics at the point
+		// of defer statement, not when deferred function is called.  We
+		// need to do the nil check outside of the wrapper.
+		if call.Op() == ir.OCALLINTER && exprp == &call.(*ir.CallExpr).X.(*ir.SelectorExpr).X {
+			check := ir.NewUnaryExpr(pos, ir.OCHECKNIL, ir.NewUnaryExpr(pos, ir.OITAB, tmp))
+			init.Append(typecheck.Stmt(check))
+		}
+
+		e.oldLoc(tmp).captured = true
+
+		tmp = ir.NewClosureVar(pos, wrapper, tmp)
+	}
+
+	*exprp = tmp
+	return tmp
+}
+
+// copyExpr creates and returns a new temporary variable within fn;
+// appends statements to init to declare and initialize it to expr;
+// and escape analyzes the data flow if analyze is true.
+func (e *escape) copyExpr(pos src.XPos, expr ir.Node, init *ir.Nodes, fn *ir.Func, analyze bool) *ir.Name {
+	if ir.HasUniquePos(expr) {
+		pos = expr.Pos()
+	}
+
+	tmp := typecheck.TempAt(pos, fn, expr.Type())
+
+	stmts := []ir.Node{
+		ir.NewDecl(pos, ir.ODCL, tmp),
+		ir.NewAssignStmt(pos, tmp, expr),
+	}
+	typecheck.Stmts(stmts)
+	init.Append(stmts...)
+
+	if analyze {
+		e.newLoc(tmp, false)
+		e.stmts(stmts)
+	}
+
+	return tmp
+}
+
+// tagHole returns a hole for evaluating an argument passed to param.
+// ks should contain the holes representing where the function
+// callee's results flows. fn is the statically-known callee function,
+// if any.
+func (e *escape) tagHole(ks []hole, fn *ir.Name, param *types.Field) hole {
+	// If this is a dynamic call, we can't rely on param.Note.
+	if fn == nil {
+		return e.heapHole()
+	}
+
+	if e.inMutualBatch(fn) {
+		return e.addr(ir.AsNode(param.Nname))
+	}
+
+	// Call to previously tagged function.
+
+	var tagKs []hole
+
+	esc := parseLeaks(param.Note)
+	if x := esc.Heap(); x >= 0 {
+		tagKs = append(tagKs, e.heapHole().shift(x))
+	}
+
+	if ks != nil {
+		for i := 0; i < numEscResults; i++ {
+			if x := esc.Result(i); x >= 0 {
+				tagKs = append(tagKs, ks[i].shift(x))
+			}
+		}
+	}
+
+	return e.teeHole(tagKs...)
+}