2380 lines
62 KiB
Go
2380 lines
62 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 ssa
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// This file implements the BUILD phase of SSA construction.
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//
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// SSA construction has two phases, CREATE and BUILD. In the CREATE phase
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// (create.go), all packages are constructed and type-checked and
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// definitions of all package members are created, method-sets are
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// computed, and wrapper methods are synthesized.
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// ssa.Packages are created in arbitrary order.
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//
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// In the BUILD phase (builder.go), the builder traverses the AST of
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// each Go source function and generates SSA instructions for the
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// function body. Initializer expressions for package-level variables
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// are emitted to the package's init() function in the order specified
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// by go/types.Info.InitOrder, then code for each function in the
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// package is generated in lexical order.
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// The BUILD phases for distinct packages are independent and are
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// executed in parallel.
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//
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// TODO(adonovan): indeed, building functions is now embarrassingly parallel.
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// Audit for concurrency then benchmark using more goroutines.
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//
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// The builder's and Program's indices (maps) are populated and
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// mutated during the CREATE phase, but during the BUILD phase they
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// remain constant. The sole exception is Prog.methodSets and its
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// related maps, which are protected by a dedicated mutex.
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import (
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"fmt"
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"go/ast"
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"go/constant"
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"go/token"
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"go/types"
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"os"
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"sync"
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)
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type opaqueType struct {
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types.Type
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name string
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}
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func (t *opaqueType) String() string { return t.name }
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var (
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varOk = newVar("ok", tBool)
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varIndex = newVar("index", tInt)
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// Type constants.
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tBool = types.Typ[types.Bool]
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tByte = types.Typ[types.Byte]
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tInt = types.Typ[types.Int]
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tInvalid = types.Typ[types.Invalid]
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tString = types.Typ[types.String]
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tUntypedNil = types.Typ[types.UntypedNil]
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tRangeIter = &opaqueType{nil, "iter"} // the type of all "range" iterators
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tEface = types.NewInterfaceType(nil, nil).Complete()
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// SSA Value constants.
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vZero = intConst(0)
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vOne = intConst(1)
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vTrue = NewConst(constant.MakeBool(true), tBool)
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)
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// builder holds state associated with the package currently being built.
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// Its methods contain all the logic for AST-to-SSA conversion.
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type builder struct{}
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// cond emits to fn code to evaluate boolean condition e and jump
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// to t or f depending on its value, performing various simplifications.
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//
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// Postcondition: fn.currentBlock is nil.
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//
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func (b *builder) cond(fn *Function, e ast.Expr, t, f *BasicBlock) {
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switch e := e.(type) {
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case *ast.ParenExpr:
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b.cond(fn, e.X, t, f)
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return
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case *ast.BinaryExpr:
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switch e.Op {
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case token.LAND:
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ltrue := fn.newBasicBlock("cond.true")
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b.cond(fn, e.X, ltrue, f)
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fn.currentBlock = ltrue
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b.cond(fn, e.Y, t, f)
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return
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case token.LOR:
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lfalse := fn.newBasicBlock("cond.false")
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b.cond(fn, e.X, t, lfalse)
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fn.currentBlock = lfalse
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b.cond(fn, e.Y, t, f)
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return
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}
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case *ast.UnaryExpr:
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if e.Op == token.NOT {
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b.cond(fn, e.X, f, t)
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return
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}
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}
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// A traditional compiler would simplify "if false" (etc) here
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// but we do not, for better fidelity to the source code.
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//
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// The value of a constant condition may be platform-specific,
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// and may cause blocks that are reachable in some configuration
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// to be hidden from subsequent analyses such as bug-finding tools.
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emitIf(fn, b.expr(fn, e), t, f)
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}
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// logicalBinop emits code to fn to evaluate e, a &&- or
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// ||-expression whose reified boolean value is wanted.
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// The value is returned.
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//
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func (b *builder) logicalBinop(fn *Function, e *ast.BinaryExpr) Value {
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rhs := fn.newBasicBlock("binop.rhs")
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done := fn.newBasicBlock("binop.done")
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// T(e) = T(e.X) = T(e.Y) after untyped constants have been
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// eliminated.
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// TODO(adonovan): not true; MyBool==MyBool yields UntypedBool.
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t := fn.Pkg.typeOf(e)
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var short Value // value of the short-circuit path
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switch e.Op {
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case token.LAND:
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b.cond(fn, e.X, rhs, done)
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short = NewConst(constant.MakeBool(false), t)
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case token.LOR:
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b.cond(fn, e.X, done, rhs)
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short = NewConst(constant.MakeBool(true), t)
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}
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// Is rhs unreachable?
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if rhs.Preds == nil {
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// Simplify false&&y to false, true||y to true.
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fn.currentBlock = done
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return short
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}
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// Is done unreachable?
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if done.Preds == nil {
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// Simplify true&&y (or false||y) to y.
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fn.currentBlock = rhs
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return b.expr(fn, e.Y)
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}
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// All edges from e.X to done carry the short-circuit value.
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var edges []Value
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for range done.Preds {
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edges = append(edges, short)
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}
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// The edge from e.Y to done carries the value of e.Y.
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fn.currentBlock = rhs
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edges = append(edges, b.expr(fn, e.Y))
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emitJump(fn, done)
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fn.currentBlock = done
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phi := &Phi{Edges: edges, Comment: e.Op.String()}
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phi.pos = e.OpPos
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phi.typ = t
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return done.emit(phi)
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}
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// exprN lowers a multi-result expression e to SSA form, emitting code
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// to fn and returning a single Value whose type is a *types.Tuple.
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// The caller must access the components via Extract.
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//
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// Multi-result expressions include CallExprs in a multi-value
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// assignment or return statement, and "value,ok" uses of
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// TypeAssertExpr, IndexExpr (when X is a map), and UnaryExpr (when Op
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// is token.ARROW).
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//
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func (b *builder) exprN(fn *Function, e ast.Expr) Value {
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typ := fn.Pkg.typeOf(e).(*types.Tuple)
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switch e := e.(type) {
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case *ast.ParenExpr:
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return b.exprN(fn, e.X)
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case *ast.CallExpr:
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// Currently, no built-in function nor type conversion
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// has multiple results, so we can avoid some of the
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// cases for single-valued CallExpr.
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var c Call
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b.setCall(fn, e, &c.Call)
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c.typ = typ
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return fn.emit(&c)
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case *ast.IndexExpr:
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mapt := fn.Pkg.typeOf(e.X).Underlying().(*types.Map)
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lookup := &Lookup{
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X: b.expr(fn, e.X),
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Index: emitConv(fn, b.expr(fn, e.Index), mapt.Key()),
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CommaOk: true,
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}
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lookup.setType(typ)
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lookup.setPos(e.Lbrack)
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return fn.emit(lookup)
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case *ast.TypeAssertExpr:
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return emitTypeTest(fn, b.expr(fn, e.X), typ.At(0).Type(), e.Lparen)
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case *ast.UnaryExpr: // must be receive <-
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unop := &UnOp{
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Op: token.ARROW,
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X: b.expr(fn, e.X),
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CommaOk: true,
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}
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unop.setType(typ)
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unop.setPos(e.OpPos)
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return fn.emit(unop)
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}
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panic(fmt.Sprintf("exprN(%T) in %s", e, fn))
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}
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// builtin emits to fn SSA instructions to implement a call to the
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// built-in function obj with the specified arguments
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// and return type. It returns the value defined by the result.
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//
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// The result is nil if no special handling was required; in this case
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// the caller should treat this like an ordinary library function
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// call.
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//
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func (b *builder) builtin(fn *Function, obj *types.Builtin, args []ast.Expr, typ types.Type, pos token.Pos) Value {
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switch obj.Name() {
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case "make":
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switch typ.Underlying().(type) {
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case *types.Slice:
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n := b.expr(fn, args[1])
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m := n
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if len(args) == 3 {
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m = b.expr(fn, args[2])
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}
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if m, ok := m.(*Const); ok {
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// treat make([]T, n, m) as new([m]T)[:n]
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cap := m.Int64()
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at := types.NewArray(typ.Underlying().(*types.Slice).Elem(), cap)
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alloc := emitNew(fn, at, pos)
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alloc.Comment = "makeslice"
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v := &Slice{
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X: alloc,
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High: n,
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}
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v.setPos(pos)
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v.setType(typ)
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return fn.emit(v)
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}
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v := &MakeSlice{
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Len: n,
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Cap: m,
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}
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v.setPos(pos)
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v.setType(typ)
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return fn.emit(v)
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case *types.Map:
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var res Value
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if len(args) == 2 {
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res = b.expr(fn, args[1])
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}
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v := &MakeMap{Reserve: res}
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v.setPos(pos)
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v.setType(typ)
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return fn.emit(v)
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case *types.Chan:
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var sz Value = vZero
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if len(args) == 2 {
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sz = b.expr(fn, args[1])
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}
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v := &MakeChan{Size: sz}
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v.setPos(pos)
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v.setType(typ)
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return fn.emit(v)
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}
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case "new":
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alloc := emitNew(fn, deref(typ), pos)
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alloc.Comment = "new"
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return alloc
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case "len", "cap":
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// Special case: len or cap of an array or *array is
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// based on the type, not the value which may be nil.
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// We must still evaluate the value, though. (If it
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// was side-effect free, the whole call would have
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// been constant-folded.)
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t := deref(fn.Pkg.typeOf(args[0])).Underlying()
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if at, ok := t.(*types.Array); ok {
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b.expr(fn, args[0]) // for effects only
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return intConst(at.Len())
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}
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// Otherwise treat as normal.
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case "panic":
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fn.emit(&Panic{
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X: emitConv(fn, b.expr(fn, args[0]), tEface),
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pos: pos,
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})
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fn.currentBlock = fn.newBasicBlock("unreachable")
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return vTrue // any non-nil Value will do
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}
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return nil // treat all others as a regular function call
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}
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// addr lowers a single-result addressable expression e to SSA form,
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// emitting code to fn and returning the location (an lvalue) defined
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// by the expression.
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//
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// If escaping is true, addr marks the base variable of the
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// addressable expression e as being a potentially escaping pointer
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// value. For example, in this code:
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//
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// a := A{
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// b: [1]B{B{c: 1}}
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// }
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// return &a.b[0].c
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//
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// the application of & causes a.b[0].c to have its address taken,
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// which means that ultimately the local variable a must be
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// heap-allocated. This is a simple but very conservative escape
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// analysis.
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//
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// Operations forming potentially escaping pointers include:
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// - &x, including when implicit in method call or composite literals.
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// - a[:] iff a is an array (not *array)
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// - references to variables in lexically enclosing functions.
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//
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func (b *builder) addr(fn *Function, e ast.Expr, escaping bool) lvalue {
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switch e := e.(type) {
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case *ast.Ident:
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if isBlankIdent(e) {
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return blank{}
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}
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obj := fn.Pkg.objectOf(e)
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v := fn.Prog.packageLevelValue(obj) // var (address)
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if v == nil {
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v = fn.lookup(obj, escaping)
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}
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return &address{addr: v, pos: e.Pos(), expr: e}
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case *ast.CompositeLit:
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t := deref(fn.Pkg.typeOf(e))
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var v *Alloc
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if escaping {
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v = emitNew(fn, t, e.Lbrace)
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} else {
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v = fn.addLocal(t, e.Lbrace)
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}
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v.Comment = "complit"
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var sb storebuf
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b.compLit(fn, v, e, true, &sb)
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sb.emit(fn)
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return &address{addr: v, pos: e.Lbrace, expr: e}
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case *ast.ParenExpr:
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return b.addr(fn, e.X, escaping)
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case *ast.SelectorExpr:
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sel, ok := fn.Pkg.info.Selections[e]
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if !ok {
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// qualified identifier
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return b.addr(fn, e.Sel, escaping)
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}
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if sel.Kind() != types.FieldVal {
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panic(sel)
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}
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wantAddr := true
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v := b.receiver(fn, e.X, wantAddr, escaping, sel)
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last := len(sel.Index()) - 1
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return &address{
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addr: emitFieldSelection(fn, v, sel.Index()[last], true, e.Sel),
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pos: e.Sel.Pos(),
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expr: e.Sel,
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}
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case *ast.IndexExpr:
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var x Value
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var et types.Type
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switch t := fn.Pkg.typeOf(e.X).Underlying().(type) {
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case *types.Array:
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x = b.addr(fn, e.X, escaping).address(fn)
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et = types.NewPointer(t.Elem())
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case *types.Pointer: // *array
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x = b.expr(fn, e.X)
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et = types.NewPointer(t.Elem().Underlying().(*types.Array).Elem())
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case *types.Slice:
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x = b.expr(fn, e.X)
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et = types.NewPointer(t.Elem())
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case *types.Map:
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return &element{
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m: b.expr(fn, e.X),
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k: emitConv(fn, b.expr(fn, e.Index), t.Key()),
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t: t.Elem(),
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pos: e.Lbrack,
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}
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default:
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panic("unexpected container type in IndexExpr: " + t.String())
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}
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v := &IndexAddr{
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X: x,
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Index: emitConv(fn, b.expr(fn, e.Index), tInt),
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}
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v.setPos(e.Lbrack)
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v.setType(et)
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return &address{addr: fn.emit(v), pos: e.Lbrack, expr: e}
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case *ast.StarExpr:
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return &address{addr: b.expr(fn, e.X), pos: e.Star, expr: e}
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}
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panic(fmt.Sprintf("unexpected address expression: %T", e))
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}
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type store struct {
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lhs lvalue
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rhs Value
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}
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type storebuf struct{ stores []store }
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func (sb *storebuf) store(lhs lvalue, rhs Value) {
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sb.stores = append(sb.stores, store{lhs, rhs})
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}
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func (sb *storebuf) emit(fn *Function) {
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for _, s := range sb.stores {
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s.lhs.store(fn, s.rhs)
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}
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}
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// assign emits to fn code to initialize the lvalue loc with the value
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// of expression e. If isZero is true, assign assumes that loc holds
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// the zero value for its type.
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//
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// This is equivalent to loc.store(fn, b.expr(fn, e)), but may generate
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// better code in some cases, e.g., for composite literals in an
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// addressable location.
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//
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// If sb is not nil, assign generates code to evaluate expression e, but
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// not to update loc. Instead, the necessary stores are appended to the
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// storebuf sb so that they can be executed later. This allows correct
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// in-place update of existing variables when the RHS is a composite
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// literal that may reference parts of the LHS.
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//
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func (b *builder) assign(fn *Function, loc lvalue, e ast.Expr, isZero bool, sb *storebuf) {
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// Can we initialize it in place?
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if e, ok := unparen(e).(*ast.CompositeLit); ok {
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// A CompositeLit never evaluates to a pointer,
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// so if the type of the location is a pointer,
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// an &-operation is implied.
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if _, ok := loc.(blank); !ok { // avoid calling blank.typ()
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if isPointer(loc.typ()) {
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ptr := b.addr(fn, e, true).address(fn)
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// copy address
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if sb != nil {
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sb.store(loc, ptr)
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} else {
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loc.store(fn, ptr)
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}
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return
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}
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}
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if _, ok := loc.(*address); ok {
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if isInterface(loc.typ()) {
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// e.g. var x interface{} = T{...}
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// Can't in-place initialize an interface value.
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// Fall back to copying.
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} else {
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// x = T{...} or x := T{...}
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addr := loc.address(fn)
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if sb != nil {
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b.compLit(fn, addr, e, isZero, sb)
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} else {
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var sb storebuf
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b.compLit(fn, addr, e, isZero, &sb)
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sb.emit(fn)
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}
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// Subtle: emit debug ref for aggregate types only;
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// slice and map are handled by store ops in compLit.
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switch loc.typ().Underlying().(type) {
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case *types.Struct, *types.Array:
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emitDebugRef(fn, e, addr, true)
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}
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return
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}
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}
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}
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// simple case: just copy
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rhs := b.expr(fn, e)
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if sb != nil {
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sb.store(loc, rhs)
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} else {
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loc.store(fn, rhs)
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}
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}
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|
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// expr lowers a single-result expression e to SSA form, emitting code
|
|
// to fn and returning the Value defined by the expression.
|
|
//
|
|
func (b *builder) expr(fn *Function, e ast.Expr) Value {
|
|
e = unparen(e)
|
|
|
|
tv := fn.Pkg.info.Types[e]
|
|
|
|
// Is expression a constant?
|
|
if tv.Value != nil {
|
|
return NewConst(tv.Value, tv.Type)
|
|
}
|
|
|
|
var v Value
|
|
if tv.Addressable() {
|
|
// Prefer pointer arithmetic ({Index,Field}Addr) followed
|
|
// by Load over subelement extraction (e.g. Index, Field),
|
|
// to avoid large copies.
|
|
v = b.addr(fn, e, false).load(fn)
|
|
} else {
|
|
v = b.expr0(fn, e, tv)
|
|
}
|
|
if fn.debugInfo() {
|
|
emitDebugRef(fn, e, v, false)
|
|
}
|
|
return v
|
|
}
|
|
|
|
func (b *builder) expr0(fn *Function, e ast.Expr, tv types.TypeAndValue) Value {
|
|
switch e := e.(type) {
|
|
case *ast.BasicLit:
|
|
panic("non-constant BasicLit") // unreachable
|
|
|
|
case *ast.FuncLit:
|
|
fn2 := &Function{
|
|
name: fmt.Sprintf("%s$%d", fn.Name(), 1+len(fn.AnonFuncs)),
|
|
Signature: fn.Pkg.typeOf(e.Type).Underlying().(*types.Signature),
|
|
pos: e.Type.Func,
|
|
parent: fn,
|
|
Pkg: fn.Pkg,
|
|
Prog: fn.Prog,
|
|
syntax: e,
|
|
}
|
|
fn.AnonFuncs = append(fn.AnonFuncs, fn2)
|
|
b.buildFunction(fn2)
|
|
if fn2.FreeVars == nil {
|
|
return fn2
|
|
}
|
|
v := &MakeClosure{Fn: fn2}
|
|
v.setType(tv.Type)
|
|
for _, fv := range fn2.FreeVars {
|
|
v.Bindings = append(v.Bindings, fv.outer)
|
|
fv.outer = nil
|
|
}
|
|
return fn.emit(v)
|
|
|
|
case *ast.TypeAssertExpr: // single-result form only
|
|
return emitTypeAssert(fn, b.expr(fn, e.X), tv.Type, e.Lparen)
|
|
|
|
case *ast.CallExpr:
|
|
if fn.Pkg.info.Types[e.Fun].IsType() {
|
|
// Explicit type conversion, e.g. string(x) or big.Int(x)
|
|
x := b.expr(fn, e.Args[0])
|
|
y := emitConv(fn, x, tv.Type)
|
|
if y != x {
|
|
switch y := y.(type) {
|
|
case *Convert:
|
|
y.pos = e.Lparen
|
|
case *ChangeType:
|
|
y.pos = e.Lparen
|
|
case *MakeInterface:
|
|
y.pos = e.Lparen
|
|
}
|
|
}
|
|
return y
|
|
}
|
|
// Call to "intrinsic" built-ins, e.g. new, make, panic.
|
|
if id, ok := unparen(e.Fun).(*ast.Ident); ok {
|
|
if obj, ok := fn.Pkg.info.Uses[id].(*types.Builtin); ok {
|
|
if v := b.builtin(fn, obj, e.Args, tv.Type, e.Lparen); v != nil {
|
|
return v
|
|
}
|
|
}
|
|
}
|
|
// Regular function call.
|
|
var v Call
|
|
b.setCall(fn, e, &v.Call)
|
|
v.setType(tv.Type)
|
|
return fn.emit(&v)
|
|
|
|
case *ast.UnaryExpr:
|
|
switch e.Op {
|
|
case token.AND: // &X --- potentially escaping.
|
|
addr := b.addr(fn, e.X, true)
|
|
if _, ok := unparen(e.X).(*ast.StarExpr); ok {
|
|
// &*p must panic if p is nil (http://golang.org/s/go12nil).
|
|
// For simplicity, we'll just (suboptimally) rely
|
|
// on the side effects of a load.
|
|
// TODO(adonovan): emit dedicated nilcheck.
|
|
addr.load(fn)
|
|
}
|
|
return addr.address(fn)
|
|
case token.ADD:
|
|
return b.expr(fn, e.X)
|
|
case token.NOT, token.ARROW, token.SUB, token.XOR: // ! <- - ^
|
|
v := &UnOp{
|
|
Op: e.Op,
|
|
X: b.expr(fn, e.X),
|
|
}
|
|
v.setPos(e.OpPos)
|
|
v.setType(tv.Type)
|
|
return fn.emit(v)
|
|
default:
|
|
panic(e.Op)
|
|
}
|
|
|
|
case *ast.BinaryExpr:
|
|
switch e.Op {
|
|
case token.LAND, token.LOR:
|
|
return b.logicalBinop(fn, e)
|
|
case token.SHL, token.SHR:
|
|
fallthrough
|
|
case token.ADD, token.SUB, token.MUL, token.QUO, token.REM, token.AND, token.OR, token.XOR, token.AND_NOT:
|
|
return emitArith(fn, e.Op, b.expr(fn, e.X), b.expr(fn, e.Y), tv.Type, e.OpPos)
|
|
|
|
case token.EQL, token.NEQ, token.GTR, token.LSS, token.LEQ, token.GEQ:
|
|
cmp := emitCompare(fn, e.Op, b.expr(fn, e.X), b.expr(fn, e.Y), e.OpPos)
|
|
// The type of x==y may be UntypedBool.
|
|
return emitConv(fn, cmp, DefaultType(tv.Type))
|
|
default:
|
|
panic("illegal op in BinaryExpr: " + e.Op.String())
|
|
}
|
|
|
|
case *ast.SliceExpr:
|
|
var low, high, max Value
|
|
var x Value
|
|
switch fn.Pkg.typeOf(e.X).Underlying().(type) {
|
|
case *types.Array:
|
|
// Potentially escaping.
|
|
x = b.addr(fn, e.X, true).address(fn)
|
|
case *types.Basic, *types.Slice, *types.Pointer: // *array
|
|
x = b.expr(fn, e.X)
|
|
default:
|
|
panic("unreachable")
|
|
}
|
|
if e.High != nil {
|
|
high = b.expr(fn, e.High)
|
|
}
|
|
if e.Low != nil {
|
|
low = b.expr(fn, e.Low)
|
|
}
|
|
if e.Slice3 {
|
|
max = b.expr(fn, e.Max)
|
|
}
|
|
v := &Slice{
|
|
X: x,
|
|
Low: low,
|
|
High: high,
|
|
Max: max,
|
|
}
|
|
v.setPos(e.Lbrack)
|
|
v.setType(tv.Type)
|
|
return fn.emit(v)
|
|
|
|
case *ast.Ident:
|
|
obj := fn.Pkg.info.Uses[e]
|
|
// Universal built-in or nil?
|
|
switch obj := obj.(type) {
|
|
case *types.Builtin:
|
|
return &Builtin{name: obj.Name(), sig: tv.Type.(*types.Signature)}
|
|
case *types.Nil:
|
|
return nilConst(tv.Type)
|
|
}
|
|
// Package-level func or var?
|
|
if v := fn.Prog.packageLevelValue(obj); v != nil {
|
|
if _, ok := obj.(*types.Var); ok {
|
|
return emitLoad(fn, v) // var (address)
|
|
}
|
|
return v // (func)
|
|
}
|
|
// Local var.
|
|
return emitLoad(fn, fn.lookup(obj, false)) // var (address)
|
|
|
|
case *ast.SelectorExpr:
|
|
sel, ok := fn.Pkg.info.Selections[e]
|
|
if !ok {
|
|
// qualified identifier
|
|
return b.expr(fn, e.Sel)
|
|
}
|
|
switch sel.Kind() {
|
|
case types.MethodExpr:
|
|
// (*T).f or T.f, the method f from the method-set of type T.
|
|
// The result is a "thunk".
|
|
return emitConv(fn, makeThunk(fn.Prog, sel), tv.Type)
|
|
|
|
case types.MethodVal:
|
|
// e.f where e is an expression and f is a method.
|
|
// The result is a "bound".
|
|
obj := sel.Obj().(*types.Func)
|
|
rt := recvType(obj)
|
|
wantAddr := isPointer(rt)
|
|
escaping := true
|
|
v := b.receiver(fn, e.X, wantAddr, escaping, sel)
|
|
if isInterface(rt) {
|
|
// If v has interface type I,
|
|
// we must emit a check that v is non-nil.
|
|
// We use: typeassert v.(I).
|
|
emitTypeAssert(fn, v, rt, token.NoPos)
|
|
}
|
|
c := &MakeClosure{
|
|
Fn: makeBound(fn.Prog, obj),
|
|
Bindings: []Value{v},
|
|
}
|
|
c.setPos(e.Sel.Pos())
|
|
c.setType(tv.Type)
|
|
return fn.emit(c)
|
|
|
|
case types.FieldVal:
|
|
indices := sel.Index()
|
|
last := len(indices) - 1
|
|
v := b.expr(fn, e.X)
|
|
v = emitImplicitSelections(fn, v, indices[:last])
|
|
v = emitFieldSelection(fn, v, indices[last], false, e.Sel)
|
|
return v
|
|
}
|
|
|
|
panic("unexpected expression-relative selector")
|
|
|
|
case *ast.IndexExpr:
|
|
switch t := fn.Pkg.typeOf(e.X).Underlying().(type) {
|
|
case *types.Array:
|
|
// Non-addressable array (in a register).
|
|
v := &Index{
|
|
X: b.expr(fn, e.X),
|
|
Index: emitConv(fn, b.expr(fn, e.Index), tInt),
|
|
}
|
|
v.setPos(e.Lbrack)
|
|
v.setType(t.Elem())
|
|
return fn.emit(v)
|
|
|
|
case *types.Map:
|
|
// Maps are not addressable.
|
|
mapt := fn.Pkg.typeOf(e.X).Underlying().(*types.Map)
|
|
v := &Lookup{
|
|
X: b.expr(fn, e.X),
|
|
Index: emitConv(fn, b.expr(fn, e.Index), mapt.Key()),
|
|
}
|
|
v.setPos(e.Lbrack)
|
|
v.setType(mapt.Elem())
|
|
return fn.emit(v)
|
|
|
|
case *types.Basic: // => string
|
|
// Strings are not addressable.
|
|
v := &Lookup{
|
|
X: b.expr(fn, e.X),
|
|
Index: b.expr(fn, e.Index),
|
|
}
|
|
v.setPos(e.Lbrack)
|
|
v.setType(tByte)
|
|
return fn.emit(v)
|
|
|
|
case *types.Slice, *types.Pointer: // *array
|
|
// Addressable slice/array; use IndexAddr and Load.
|
|
return b.addr(fn, e, false).load(fn)
|
|
|
|
default:
|
|
panic("unexpected container type in IndexExpr: " + t.String())
|
|
}
|
|
|
|
case *ast.CompositeLit, *ast.StarExpr:
|
|
// Addressable types (lvalues)
|
|
return b.addr(fn, e, false).load(fn)
|
|
}
|
|
|
|
panic(fmt.Sprintf("unexpected expr: %T", e))
|
|
}
|
|
|
|
// stmtList emits to fn code for all statements in list.
|
|
func (b *builder) stmtList(fn *Function, list []ast.Stmt) {
|
|
for _, s := range list {
|
|
b.stmt(fn, s)
|
|
}
|
|
}
|
|
|
|
// receiver emits to fn code for expression e in the "receiver"
|
|
// position of selection e.f (where f may be a field or a method) and
|
|
// returns the effective receiver after applying the implicit field
|
|
// selections of sel.
|
|
//
|
|
// wantAddr requests that the result is an an address. If
|
|
// !sel.Indirect(), this may require that e be built in addr() mode; it
|
|
// must thus be addressable.
|
|
//
|
|
// escaping is defined as per builder.addr().
|
|
//
|
|
func (b *builder) receiver(fn *Function, e ast.Expr, wantAddr, escaping bool, sel *types.Selection) Value {
|
|
var v Value
|
|
if wantAddr && !sel.Indirect() && !isPointer(fn.Pkg.typeOf(e)) {
|
|
v = b.addr(fn, e, escaping).address(fn)
|
|
} else {
|
|
v = b.expr(fn, e)
|
|
}
|
|
|
|
last := len(sel.Index()) - 1
|
|
v = emitImplicitSelections(fn, v, sel.Index()[:last])
|
|
if !wantAddr && isPointer(v.Type()) {
|
|
v = emitLoad(fn, v)
|
|
}
|
|
return v
|
|
}
|
|
|
|
// setCallFunc populates the function parts of a CallCommon structure
|
|
// (Func, Method, Recv, Args[0]) based on the kind of invocation
|
|
// occurring in e.
|
|
//
|
|
func (b *builder) setCallFunc(fn *Function, e *ast.CallExpr, c *CallCommon) {
|
|
c.pos = e.Lparen
|
|
|
|
// Is this a method call?
|
|
if selector, ok := unparen(e.Fun).(*ast.SelectorExpr); ok {
|
|
sel, ok := fn.Pkg.info.Selections[selector]
|
|
if ok && sel.Kind() == types.MethodVal {
|
|
obj := sel.Obj().(*types.Func)
|
|
recv := recvType(obj)
|
|
wantAddr := isPointer(recv)
|
|
escaping := true
|
|
v := b.receiver(fn, selector.X, wantAddr, escaping, sel)
|
|
if isInterface(recv) {
|
|
// Invoke-mode call.
|
|
c.Value = v
|
|
c.Method = obj
|
|
} else {
|
|
// "Call"-mode call.
|
|
c.Value = fn.Prog.declaredFunc(obj)
|
|
c.Args = append(c.Args, v)
|
|
}
|
|
return
|
|
}
|
|
|
|
// sel.Kind()==MethodExpr indicates T.f() or (*T).f():
|
|
// a statically dispatched call to the method f in the
|
|
// method-set of T or *T. T may be an interface.
|
|
//
|
|
// e.Fun would evaluate to a concrete method, interface
|
|
// wrapper function, or promotion wrapper.
|
|
//
|
|
// For now, we evaluate it in the usual way.
|
|
//
|
|
// TODO(adonovan): opt: inline expr() here, to make the
|
|
// call static and to avoid generation of wrappers.
|
|
// It's somewhat tricky as it may consume the first
|
|
// actual parameter if the call is "invoke" mode.
|
|
//
|
|
// Examples:
|
|
// type T struct{}; func (T) f() {} // "call" mode
|
|
// type T interface { f() } // "invoke" mode
|
|
//
|
|
// type S struct{ T }
|
|
//
|
|
// var s S
|
|
// S.f(s)
|
|
// (*S).f(&s)
|
|
//
|
|
// Suggested approach:
|
|
// - consume the first actual parameter expression
|
|
// and build it with b.expr().
|
|
// - apply implicit field selections.
|
|
// - use MethodVal logic to populate fields of c.
|
|
}
|
|
|
|
// Evaluate the function operand in the usual way.
|
|
c.Value = b.expr(fn, e.Fun)
|
|
}
|
|
|
|
// emitCallArgs emits to f code for the actual parameters of call e to
|
|
// a (possibly built-in) function of effective type sig.
|
|
// The argument values are appended to args, which is then returned.
|
|
//
|
|
func (b *builder) emitCallArgs(fn *Function, sig *types.Signature, e *ast.CallExpr, args []Value) []Value {
|
|
// f(x, y, z...): pass slice z straight through.
|
|
if e.Ellipsis != 0 {
|
|
for i, arg := range e.Args {
|
|
v := emitConv(fn, b.expr(fn, arg), sig.Params().At(i).Type())
|
|
args = append(args, v)
|
|
}
|
|
return args
|
|
}
|
|
|
|
offset := len(args) // 1 if call has receiver, 0 otherwise
|
|
|
|
// Evaluate actual parameter expressions.
|
|
//
|
|
// If this is a chained call of the form f(g()) where g has
|
|
// multiple return values (MRV), they are flattened out into
|
|
// args; a suffix of them may end up in a varargs slice.
|
|
for _, arg := range e.Args {
|
|
v := b.expr(fn, arg)
|
|
if ttuple, ok := v.Type().(*types.Tuple); ok { // MRV chain
|
|
for i, n := 0, ttuple.Len(); i < n; i++ {
|
|
args = append(args, emitExtract(fn, v, i))
|
|
}
|
|
} else {
|
|
args = append(args, v)
|
|
}
|
|
}
|
|
|
|
// Actual->formal assignability conversions for normal parameters.
|
|
np := sig.Params().Len() // number of normal parameters
|
|
if sig.Variadic() {
|
|
np--
|
|
}
|
|
for i := 0; i < np; i++ {
|
|
args[offset+i] = emitConv(fn, args[offset+i], sig.Params().At(i).Type())
|
|
}
|
|
|
|
// Actual->formal assignability conversions for variadic parameter,
|
|
// and construction of slice.
|
|
if sig.Variadic() {
|
|
varargs := args[offset+np:]
|
|
st := sig.Params().At(np).Type().(*types.Slice)
|
|
vt := st.Elem()
|
|
if len(varargs) == 0 {
|
|
args = append(args, nilConst(st))
|
|
} else {
|
|
// Replace a suffix of args with a slice containing it.
|
|
at := types.NewArray(vt, int64(len(varargs)))
|
|
a := emitNew(fn, at, token.NoPos)
|
|
a.setPos(e.Rparen)
|
|
a.Comment = "varargs"
|
|
for i, arg := range varargs {
|
|
iaddr := &IndexAddr{
|
|
X: a,
|
|
Index: intConst(int64(i)),
|
|
}
|
|
iaddr.setType(types.NewPointer(vt))
|
|
fn.emit(iaddr)
|
|
emitStore(fn, iaddr, arg, arg.Pos())
|
|
}
|
|
s := &Slice{X: a}
|
|
s.setType(st)
|
|
args[offset+np] = fn.emit(s)
|
|
args = args[:offset+np+1]
|
|
}
|
|
}
|
|
return args
|
|
}
|
|
|
|
// setCall emits to fn code to evaluate all the parameters of a function
|
|
// call e, and populates *c with those values.
|
|
//
|
|
func (b *builder) setCall(fn *Function, e *ast.CallExpr, c *CallCommon) {
|
|
// First deal with the f(...) part and optional receiver.
|
|
b.setCallFunc(fn, e, c)
|
|
|
|
// Then append the other actual parameters.
|
|
sig, _ := fn.Pkg.typeOf(e.Fun).Underlying().(*types.Signature)
|
|
if sig == nil {
|
|
panic(fmt.Sprintf("no signature for call of %s", e.Fun))
|
|
}
|
|
c.Args = b.emitCallArgs(fn, sig, e, c.Args)
|
|
}
|
|
|
|
// assignOp emits to fn code to perform loc <op>= val.
|
|
func (b *builder) assignOp(fn *Function, loc lvalue, val Value, op token.Token, pos token.Pos) {
|
|
oldv := loc.load(fn)
|
|
loc.store(fn, emitArith(fn, op, oldv, emitConv(fn, val, oldv.Type()), loc.typ(), pos))
|
|
}
|
|
|
|
// localValueSpec emits to fn code to define all of the vars in the
|
|
// function-local ValueSpec, spec.
|
|
//
|
|
func (b *builder) localValueSpec(fn *Function, spec *ast.ValueSpec) {
|
|
switch {
|
|
case len(spec.Values) == len(spec.Names):
|
|
// e.g. var x, y = 0, 1
|
|
// 1:1 assignment
|
|
for i, id := range spec.Names {
|
|
if !isBlankIdent(id) {
|
|
fn.addLocalForIdent(id)
|
|
}
|
|
lval := b.addr(fn, id, false) // non-escaping
|
|
b.assign(fn, lval, spec.Values[i], true, nil)
|
|
}
|
|
|
|
case len(spec.Values) == 0:
|
|
// e.g. var x, y int
|
|
// Locals are implicitly zero-initialized.
|
|
for _, id := range spec.Names {
|
|
if !isBlankIdent(id) {
|
|
lhs := fn.addLocalForIdent(id)
|
|
if fn.debugInfo() {
|
|
emitDebugRef(fn, id, lhs, true)
|
|
}
|
|
}
|
|
}
|
|
|
|
default:
|
|
// e.g. var x, y = pos()
|
|
tuple := b.exprN(fn, spec.Values[0])
|
|
for i, id := range spec.Names {
|
|
if !isBlankIdent(id) {
|
|
fn.addLocalForIdent(id)
|
|
lhs := b.addr(fn, id, false) // non-escaping
|
|
lhs.store(fn, emitExtract(fn, tuple, i))
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// assignStmt emits code to fn for a parallel assignment of rhss to lhss.
|
|
// isDef is true if this is a short variable declaration (:=).
|
|
//
|
|
// Note the similarity with localValueSpec.
|
|
//
|
|
func (b *builder) assignStmt(fn *Function, lhss, rhss []ast.Expr, isDef bool) {
|
|
// Side effects of all LHSs and RHSs must occur in left-to-right order.
|
|
lvals := make([]lvalue, len(lhss))
|
|
isZero := make([]bool, len(lhss))
|
|
for i, lhs := range lhss {
|
|
var lval lvalue = blank{}
|
|
if !isBlankIdent(lhs) {
|
|
if isDef {
|
|
if obj := fn.Pkg.info.Defs[lhs.(*ast.Ident)]; obj != nil {
|
|
fn.addNamedLocal(obj)
|
|
isZero[i] = true
|
|
}
|
|
}
|
|
lval = b.addr(fn, lhs, false) // non-escaping
|
|
}
|
|
lvals[i] = lval
|
|
}
|
|
if len(lhss) == len(rhss) {
|
|
// Simple assignment: x = f() (!isDef)
|
|
// Parallel assignment: x, y = f(), g() (!isDef)
|
|
// or short var decl: x, y := f(), g() (isDef)
|
|
//
|
|
// In all cases, the RHSs may refer to the LHSs,
|
|
// so we need a storebuf.
|
|
var sb storebuf
|
|
for i := range rhss {
|
|
b.assign(fn, lvals[i], rhss[i], isZero[i], &sb)
|
|
}
|
|
sb.emit(fn)
|
|
} else {
|
|
// e.g. x, y = pos()
|
|
tuple := b.exprN(fn, rhss[0])
|
|
emitDebugRef(fn, rhss[0], tuple, false)
|
|
for i, lval := range lvals {
|
|
lval.store(fn, emitExtract(fn, tuple, i))
|
|
}
|
|
}
|
|
}
|
|
|
|
// arrayLen returns the length of the array whose composite literal elements are elts.
|
|
func (b *builder) arrayLen(fn *Function, elts []ast.Expr) int64 {
|
|
var max int64 = -1
|
|
var i int64 = -1
|
|
for _, e := range elts {
|
|
if kv, ok := e.(*ast.KeyValueExpr); ok {
|
|
i = b.expr(fn, kv.Key).(*Const).Int64()
|
|
} else {
|
|
i++
|
|
}
|
|
if i > max {
|
|
max = i
|
|
}
|
|
}
|
|
return max + 1
|
|
}
|
|
|
|
// compLit emits to fn code to initialize a composite literal e at
|
|
// address addr with type typ.
|
|
//
|
|
// Nested composite literals are recursively initialized in place
|
|
// where possible. If isZero is true, compLit assumes that addr
|
|
// holds the zero value for typ.
|
|
//
|
|
// Because the elements of a composite literal may refer to the
|
|
// variables being updated, as in the second line below,
|
|
// x := T{a: 1}
|
|
// x = T{a: x.a}
|
|
// all the reads must occur before all the writes. Thus all stores to
|
|
// loc are emitted to the storebuf sb for later execution.
|
|
//
|
|
// A CompositeLit may have pointer type only in the recursive (nested)
|
|
// case when the type name is implicit. e.g. in []*T{{}}, the inner
|
|
// literal has type *T behaves like &T{}.
|
|
// In that case, addr must hold a T, not a *T.
|
|
//
|
|
func (b *builder) compLit(fn *Function, addr Value, e *ast.CompositeLit, isZero bool, sb *storebuf) {
|
|
typ := deref(fn.Pkg.typeOf(e))
|
|
switch t := typ.Underlying().(type) {
|
|
case *types.Struct:
|
|
if !isZero && len(e.Elts) != t.NumFields() {
|
|
// memclear
|
|
sb.store(&address{addr, e.Lbrace, nil},
|
|
zeroValue(fn, deref(addr.Type())))
|
|
isZero = true
|
|
}
|
|
for i, e := range e.Elts {
|
|
fieldIndex := i
|
|
pos := e.Pos()
|
|
if kv, ok := e.(*ast.KeyValueExpr); ok {
|
|
fname := kv.Key.(*ast.Ident).Name
|
|
for i, n := 0, t.NumFields(); i < n; i++ {
|
|
sf := t.Field(i)
|
|
if sf.Name() == fname {
|
|
fieldIndex = i
|
|
pos = kv.Colon
|
|
e = kv.Value
|
|
break
|
|
}
|
|
}
|
|
}
|
|
sf := t.Field(fieldIndex)
|
|
faddr := &FieldAddr{
|
|
X: addr,
|
|
Field: fieldIndex,
|
|
}
|
|
faddr.setType(types.NewPointer(sf.Type()))
|
|
fn.emit(faddr)
|
|
b.assign(fn, &address{addr: faddr, pos: pos, expr: e}, e, isZero, sb)
|
|
}
|
|
|
|
case *types.Array, *types.Slice:
|
|
var at *types.Array
|
|
var array Value
|
|
switch t := t.(type) {
|
|
case *types.Slice:
|
|
at = types.NewArray(t.Elem(), b.arrayLen(fn, e.Elts))
|
|
alloc := emitNew(fn, at, e.Lbrace)
|
|
alloc.Comment = "slicelit"
|
|
array = alloc
|
|
case *types.Array:
|
|
at = t
|
|
array = addr
|
|
|
|
if !isZero && int64(len(e.Elts)) != at.Len() {
|
|
// memclear
|
|
sb.store(&address{array, e.Lbrace, nil},
|
|
zeroValue(fn, deref(array.Type())))
|
|
}
|
|
}
|
|
|
|
var idx *Const
|
|
for _, e := range e.Elts {
|
|
pos := e.Pos()
|
|
if kv, ok := e.(*ast.KeyValueExpr); ok {
|
|
idx = b.expr(fn, kv.Key).(*Const)
|
|
pos = kv.Colon
|
|
e = kv.Value
|
|
} else {
|
|
var idxval int64
|
|
if idx != nil {
|
|
idxval = idx.Int64() + 1
|
|
}
|
|
idx = intConst(idxval)
|
|
}
|
|
iaddr := &IndexAddr{
|
|
X: array,
|
|
Index: idx,
|
|
}
|
|
iaddr.setType(types.NewPointer(at.Elem()))
|
|
fn.emit(iaddr)
|
|
if t != at { // slice
|
|
// backing array is unaliased => storebuf not needed.
|
|
b.assign(fn, &address{addr: iaddr, pos: pos, expr: e}, e, true, nil)
|
|
} else {
|
|
b.assign(fn, &address{addr: iaddr, pos: pos, expr: e}, e, true, sb)
|
|
}
|
|
}
|
|
|
|
if t != at { // slice
|
|
s := &Slice{X: array}
|
|
s.setPos(e.Lbrace)
|
|
s.setType(typ)
|
|
sb.store(&address{addr: addr, pos: e.Lbrace, expr: e}, fn.emit(s))
|
|
}
|
|
|
|
case *types.Map:
|
|
m := &MakeMap{Reserve: intConst(int64(len(e.Elts)))}
|
|
m.setPos(e.Lbrace)
|
|
m.setType(typ)
|
|
fn.emit(m)
|
|
for _, e := range e.Elts {
|
|
e := e.(*ast.KeyValueExpr)
|
|
|
|
// If a key expression in a map literal is itself a
|
|
// composite literal, the type may be omitted.
|
|
// For example:
|
|
// map[*struct{}]bool{{}: true}
|
|
// An &-operation may be implied:
|
|
// map[*struct{}]bool{&struct{}{}: true}
|
|
var key Value
|
|
if _, ok := unparen(e.Key).(*ast.CompositeLit); ok && isPointer(t.Key()) {
|
|
// A CompositeLit never evaluates to a pointer,
|
|
// so if the type of the location is a pointer,
|
|
// an &-operation is implied.
|
|
key = b.addr(fn, e.Key, true).address(fn)
|
|
} else {
|
|
key = b.expr(fn, e.Key)
|
|
}
|
|
|
|
loc := element{
|
|
m: m,
|
|
k: emitConv(fn, key, t.Key()),
|
|
t: t.Elem(),
|
|
pos: e.Colon,
|
|
}
|
|
|
|
// We call assign() only because it takes care
|
|
// of any &-operation required in the recursive
|
|
// case, e.g.,
|
|
// map[int]*struct{}{0: {}} implies &struct{}{}.
|
|
// In-place update is of course impossible,
|
|
// and no storebuf is needed.
|
|
b.assign(fn, &loc, e.Value, true, nil)
|
|
}
|
|
sb.store(&address{addr: addr, pos: e.Lbrace, expr: e}, m)
|
|
|
|
default:
|
|
panic("unexpected CompositeLit type: " + t.String())
|
|
}
|
|
}
|
|
|
|
// switchStmt emits to fn code for the switch statement s, optionally
|
|
// labelled by label.
|
|
//
|
|
func (b *builder) switchStmt(fn *Function, s *ast.SwitchStmt, label *lblock) {
|
|
// We treat SwitchStmt like a sequential if-else chain.
|
|
// Multiway dispatch can be recovered later by ssautil.Switches()
|
|
// to those cases that are free of side effects.
|
|
if s.Init != nil {
|
|
b.stmt(fn, s.Init)
|
|
}
|
|
var tag Value = vTrue
|
|
if s.Tag != nil {
|
|
tag = b.expr(fn, s.Tag)
|
|
}
|
|
done := fn.newBasicBlock("switch.done")
|
|
if label != nil {
|
|
label._break = done
|
|
}
|
|
// We pull the default case (if present) down to the end.
|
|
// But each fallthrough label must point to the next
|
|
// body block in source order, so we preallocate a
|
|
// body block (fallthru) for the next case.
|
|
// Unfortunately this makes for a confusing block order.
|
|
var dfltBody *[]ast.Stmt
|
|
var dfltFallthrough *BasicBlock
|
|
var fallthru, dfltBlock *BasicBlock
|
|
ncases := len(s.Body.List)
|
|
for i, clause := range s.Body.List {
|
|
body := fallthru
|
|
if body == nil {
|
|
body = fn.newBasicBlock("switch.body") // first case only
|
|
}
|
|
|
|
// Preallocate body block for the next case.
|
|
fallthru = done
|
|
if i+1 < ncases {
|
|
fallthru = fn.newBasicBlock("switch.body")
|
|
}
|
|
|
|
cc := clause.(*ast.CaseClause)
|
|
if cc.List == nil {
|
|
// Default case.
|
|
dfltBody = &cc.Body
|
|
dfltFallthrough = fallthru
|
|
dfltBlock = body
|
|
continue
|
|
}
|
|
|
|
var nextCond *BasicBlock
|
|
for _, cond := range cc.List {
|
|
nextCond = fn.newBasicBlock("switch.next")
|
|
// TODO(adonovan): opt: when tag==vTrue, we'd
|
|
// get better code if we use b.cond(cond)
|
|
// instead of BinOp(EQL, tag, b.expr(cond))
|
|
// followed by If. Don't forget conversions
|
|
// though.
|
|
cond := emitCompare(fn, token.EQL, tag, b.expr(fn, cond), cond.Pos())
|
|
emitIf(fn, cond, body, nextCond)
|
|
fn.currentBlock = nextCond
|
|
}
|
|
fn.currentBlock = body
|
|
fn.targets = &targets{
|
|
tail: fn.targets,
|
|
_break: done,
|
|
_fallthrough: fallthru,
|
|
}
|
|
b.stmtList(fn, cc.Body)
|
|
fn.targets = fn.targets.tail
|
|
emitJump(fn, done)
|
|
fn.currentBlock = nextCond
|
|
}
|
|
if dfltBlock != nil {
|
|
emitJump(fn, dfltBlock)
|
|
fn.currentBlock = dfltBlock
|
|
fn.targets = &targets{
|
|
tail: fn.targets,
|
|
_break: done,
|
|
_fallthrough: dfltFallthrough,
|
|
}
|
|
b.stmtList(fn, *dfltBody)
|
|
fn.targets = fn.targets.tail
|
|
}
|
|
emitJump(fn, done)
|
|
fn.currentBlock = done
|
|
}
|
|
|
|
// typeSwitchStmt emits to fn code for the type switch statement s, optionally
|
|
// labelled by label.
|
|
//
|
|
func (b *builder) typeSwitchStmt(fn *Function, s *ast.TypeSwitchStmt, label *lblock) {
|
|
// We treat TypeSwitchStmt like a sequential if-else chain.
|
|
// Multiway dispatch can be recovered later by ssautil.Switches().
|
|
|
|
// Typeswitch lowering:
|
|
//
|
|
// var x X
|
|
// switch y := x.(type) {
|
|
// case T1, T2: S1 // >1 (y := x)
|
|
// case nil: SN // nil (y := x)
|
|
// default: SD // 0 types (y := x)
|
|
// case T3: S3 // 1 type (y := x.(T3))
|
|
// }
|
|
//
|
|
// ...s.Init...
|
|
// x := eval x
|
|
// .caseT1:
|
|
// t1, ok1 := typeswitch,ok x <T1>
|
|
// if ok1 then goto S1 else goto .caseT2
|
|
// .caseT2:
|
|
// t2, ok2 := typeswitch,ok x <T2>
|
|
// if ok2 then goto S1 else goto .caseNil
|
|
// .S1:
|
|
// y := x
|
|
// ...S1...
|
|
// goto done
|
|
// .caseNil:
|
|
// if t2, ok2 := typeswitch,ok x <T2>
|
|
// if x == nil then goto SN else goto .caseT3
|
|
// .SN:
|
|
// y := x
|
|
// ...SN...
|
|
// goto done
|
|
// .caseT3:
|
|
// t3, ok3 := typeswitch,ok x <T3>
|
|
// if ok3 then goto S3 else goto default
|
|
// .S3:
|
|
// y := t3
|
|
// ...S3...
|
|
// goto done
|
|
// .default:
|
|
// y := x
|
|
// ...SD...
|
|
// goto done
|
|
// .done:
|
|
|
|
if s.Init != nil {
|
|
b.stmt(fn, s.Init)
|
|
}
|
|
|
|
var x Value
|
|
switch ass := s.Assign.(type) {
|
|
case *ast.ExprStmt: // x.(type)
|
|
x = b.expr(fn, unparen(ass.X).(*ast.TypeAssertExpr).X)
|
|
case *ast.AssignStmt: // y := x.(type)
|
|
x = b.expr(fn, unparen(ass.Rhs[0]).(*ast.TypeAssertExpr).X)
|
|
}
|
|
|
|
done := fn.newBasicBlock("typeswitch.done")
|
|
if label != nil {
|
|
label._break = done
|
|
}
|
|
var default_ *ast.CaseClause
|
|
for _, clause := range s.Body.List {
|
|
cc := clause.(*ast.CaseClause)
|
|
if cc.List == nil {
|
|
default_ = cc
|
|
continue
|
|
}
|
|
body := fn.newBasicBlock("typeswitch.body")
|
|
var next *BasicBlock
|
|
var casetype types.Type
|
|
var ti Value // ti, ok := typeassert,ok x <Ti>
|
|
for _, cond := range cc.List {
|
|
next = fn.newBasicBlock("typeswitch.next")
|
|
casetype = fn.Pkg.typeOf(cond)
|
|
var condv Value
|
|
if casetype == tUntypedNil {
|
|
condv = emitCompare(fn, token.EQL, x, nilConst(x.Type()), token.NoPos)
|
|
ti = x
|
|
} else {
|
|
yok := emitTypeTest(fn, x, casetype, cc.Case)
|
|
ti = emitExtract(fn, yok, 0)
|
|
condv = emitExtract(fn, yok, 1)
|
|
}
|
|
emitIf(fn, condv, body, next)
|
|
fn.currentBlock = next
|
|
}
|
|
if len(cc.List) != 1 {
|
|
ti = x
|
|
}
|
|
fn.currentBlock = body
|
|
b.typeCaseBody(fn, cc, ti, done)
|
|
fn.currentBlock = next
|
|
}
|
|
if default_ != nil {
|
|
b.typeCaseBody(fn, default_, x, done)
|
|
} else {
|
|
emitJump(fn, done)
|
|
}
|
|
fn.currentBlock = done
|
|
}
|
|
|
|
func (b *builder) typeCaseBody(fn *Function, cc *ast.CaseClause, x Value, done *BasicBlock) {
|
|
if obj := fn.Pkg.info.Implicits[cc]; obj != nil {
|
|
// In a switch y := x.(type), each case clause
|
|
// implicitly declares a distinct object y.
|
|
// In a single-type case, y has that type.
|
|
// In multi-type cases, 'case nil' and default,
|
|
// y has the same type as the interface operand.
|
|
emitStore(fn, fn.addNamedLocal(obj), x, obj.Pos())
|
|
}
|
|
fn.targets = &targets{
|
|
tail: fn.targets,
|
|
_break: done,
|
|
}
|
|
b.stmtList(fn, cc.Body)
|
|
fn.targets = fn.targets.tail
|
|
emitJump(fn, done)
|
|
}
|
|
|
|
// selectStmt emits to fn code for the select statement s, optionally
|
|
// labelled by label.
|
|
//
|
|
func (b *builder) selectStmt(fn *Function, s *ast.SelectStmt, label *lblock) {
|
|
// A blocking select of a single case degenerates to a
|
|
// simple send or receive.
|
|
// TODO(adonovan): opt: is this optimization worth its weight?
|
|
if len(s.Body.List) == 1 {
|
|
clause := s.Body.List[0].(*ast.CommClause)
|
|
if clause.Comm != nil {
|
|
b.stmt(fn, clause.Comm)
|
|
done := fn.newBasicBlock("select.done")
|
|
if label != nil {
|
|
label._break = done
|
|
}
|
|
fn.targets = &targets{
|
|
tail: fn.targets,
|
|
_break: done,
|
|
}
|
|
b.stmtList(fn, clause.Body)
|
|
fn.targets = fn.targets.tail
|
|
emitJump(fn, done)
|
|
fn.currentBlock = done
|
|
return
|
|
}
|
|
}
|
|
|
|
// First evaluate all channels in all cases, and find
|
|
// the directions of each state.
|
|
var states []*SelectState
|
|
blocking := true
|
|
debugInfo := fn.debugInfo()
|
|
for _, clause := range s.Body.List {
|
|
var st *SelectState
|
|
switch comm := clause.(*ast.CommClause).Comm.(type) {
|
|
case nil: // default case
|
|
blocking = false
|
|
continue
|
|
|
|
case *ast.SendStmt: // ch<- i
|
|
ch := b.expr(fn, comm.Chan)
|
|
st = &SelectState{
|
|
Dir: types.SendOnly,
|
|
Chan: ch,
|
|
Send: emitConv(fn, b.expr(fn, comm.Value),
|
|
ch.Type().Underlying().(*types.Chan).Elem()),
|
|
Pos: comm.Arrow,
|
|
}
|
|
if debugInfo {
|
|
st.DebugNode = comm
|
|
}
|
|
|
|
case *ast.AssignStmt: // x := <-ch
|
|
recv := unparen(comm.Rhs[0]).(*ast.UnaryExpr)
|
|
st = &SelectState{
|
|
Dir: types.RecvOnly,
|
|
Chan: b.expr(fn, recv.X),
|
|
Pos: recv.OpPos,
|
|
}
|
|
if debugInfo {
|
|
st.DebugNode = recv
|
|
}
|
|
|
|
case *ast.ExprStmt: // <-ch
|
|
recv := unparen(comm.X).(*ast.UnaryExpr)
|
|
st = &SelectState{
|
|
Dir: types.RecvOnly,
|
|
Chan: b.expr(fn, recv.X),
|
|
Pos: recv.OpPos,
|
|
}
|
|
if debugInfo {
|
|
st.DebugNode = recv
|
|
}
|
|
}
|
|
states = append(states, st)
|
|
}
|
|
|
|
// We dispatch on the (fair) result of Select using a
|
|
// sequential if-else chain, in effect:
|
|
//
|
|
// idx, recvOk, r0...r_n-1 := select(...)
|
|
// if idx == 0 { // receive on channel 0 (first receive => r0)
|
|
// x, ok := r0, recvOk
|
|
// ...state0...
|
|
// } else if v == 1 { // send on channel 1
|
|
// ...state1...
|
|
// } else {
|
|
// ...default...
|
|
// }
|
|
sel := &Select{
|
|
States: states,
|
|
Blocking: blocking,
|
|
}
|
|
sel.setPos(s.Select)
|
|
var vars []*types.Var
|
|
vars = append(vars, varIndex, varOk)
|
|
for _, st := range states {
|
|
if st.Dir == types.RecvOnly {
|
|
tElem := st.Chan.Type().Underlying().(*types.Chan).Elem()
|
|
vars = append(vars, anonVar(tElem))
|
|
}
|
|
}
|
|
sel.setType(types.NewTuple(vars...))
|
|
|
|
fn.emit(sel)
|
|
idx := emitExtract(fn, sel, 0)
|
|
|
|
done := fn.newBasicBlock("select.done")
|
|
if label != nil {
|
|
label._break = done
|
|
}
|
|
|
|
var defaultBody *[]ast.Stmt
|
|
state := 0
|
|
r := 2 // index in 'sel' tuple of value; increments if st.Dir==RECV
|
|
for _, cc := range s.Body.List {
|
|
clause := cc.(*ast.CommClause)
|
|
if clause.Comm == nil {
|
|
defaultBody = &clause.Body
|
|
continue
|
|
}
|
|
body := fn.newBasicBlock("select.body")
|
|
next := fn.newBasicBlock("select.next")
|
|
emitIf(fn, emitCompare(fn, token.EQL, idx, intConst(int64(state)), token.NoPos), body, next)
|
|
fn.currentBlock = body
|
|
fn.targets = &targets{
|
|
tail: fn.targets,
|
|
_break: done,
|
|
}
|
|
switch comm := clause.Comm.(type) {
|
|
case *ast.ExprStmt: // <-ch
|
|
if debugInfo {
|
|
v := emitExtract(fn, sel, r)
|
|
emitDebugRef(fn, states[state].DebugNode.(ast.Expr), v, false)
|
|
}
|
|
r++
|
|
|
|
case *ast.AssignStmt: // x := <-states[state].Chan
|
|
if comm.Tok == token.DEFINE {
|
|
fn.addLocalForIdent(comm.Lhs[0].(*ast.Ident))
|
|
}
|
|
x := b.addr(fn, comm.Lhs[0], false) // non-escaping
|
|
v := emitExtract(fn, sel, r)
|
|
if debugInfo {
|
|
emitDebugRef(fn, states[state].DebugNode.(ast.Expr), v, false)
|
|
}
|
|
x.store(fn, v)
|
|
|
|
if len(comm.Lhs) == 2 { // x, ok := ...
|
|
if comm.Tok == token.DEFINE {
|
|
fn.addLocalForIdent(comm.Lhs[1].(*ast.Ident))
|
|
}
|
|
ok := b.addr(fn, comm.Lhs[1], false) // non-escaping
|
|
ok.store(fn, emitExtract(fn, sel, 1))
|
|
}
|
|
r++
|
|
}
|
|
b.stmtList(fn, clause.Body)
|
|
fn.targets = fn.targets.tail
|
|
emitJump(fn, done)
|
|
fn.currentBlock = next
|
|
state++
|
|
}
|
|
if defaultBody != nil {
|
|
fn.targets = &targets{
|
|
tail: fn.targets,
|
|
_break: done,
|
|
}
|
|
b.stmtList(fn, *defaultBody)
|
|
fn.targets = fn.targets.tail
|
|
} else {
|
|
// A blocking select must match some case.
|
|
// (This should really be a runtime.errorString, not a string.)
|
|
fn.emit(&Panic{
|
|
X: emitConv(fn, stringConst("blocking select matched no case"), tEface),
|
|
})
|
|
fn.currentBlock = fn.newBasicBlock("unreachable")
|
|
}
|
|
emitJump(fn, done)
|
|
fn.currentBlock = done
|
|
}
|
|
|
|
// forStmt emits to fn code for the for statement s, optionally
|
|
// labelled by label.
|
|
//
|
|
func (b *builder) forStmt(fn *Function, s *ast.ForStmt, label *lblock) {
|
|
// ...init...
|
|
// jump loop
|
|
// loop:
|
|
// if cond goto body else done
|
|
// body:
|
|
// ...body...
|
|
// jump post
|
|
// post: (target of continue)
|
|
// ...post...
|
|
// jump loop
|
|
// done: (target of break)
|
|
if s.Init != nil {
|
|
b.stmt(fn, s.Init)
|
|
}
|
|
body := fn.newBasicBlock("for.body")
|
|
done := fn.newBasicBlock("for.done") // target of 'break'
|
|
loop := body // target of back-edge
|
|
if s.Cond != nil {
|
|
loop = fn.newBasicBlock("for.loop")
|
|
}
|
|
cont := loop // target of 'continue'
|
|
if s.Post != nil {
|
|
cont = fn.newBasicBlock("for.post")
|
|
}
|
|
if label != nil {
|
|
label._break = done
|
|
label._continue = cont
|
|
}
|
|
emitJump(fn, loop)
|
|
fn.currentBlock = loop
|
|
if loop != body {
|
|
b.cond(fn, s.Cond, body, done)
|
|
fn.currentBlock = body
|
|
}
|
|
fn.targets = &targets{
|
|
tail: fn.targets,
|
|
_break: done,
|
|
_continue: cont,
|
|
}
|
|
b.stmt(fn, s.Body)
|
|
fn.targets = fn.targets.tail
|
|
emitJump(fn, cont)
|
|
|
|
if s.Post != nil {
|
|
fn.currentBlock = cont
|
|
b.stmt(fn, s.Post)
|
|
emitJump(fn, loop) // back-edge
|
|
}
|
|
fn.currentBlock = done
|
|
}
|
|
|
|
// rangeIndexed emits to fn the header for an integer-indexed loop
|
|
// over array, *array or slice value x.
|
|
// The v result is defined only if tv is non-nil.
|
|
// forPos is the position of the "for" token.
|
|
//
|
|
func (b *builder) rangeIndexed(fn *Function, x Value, tv types.Type, pos token.Pos) (k, v Value, loop, done *BasicBlock) {
|
|
//
|
|
// length = len(x)
|
|
// index = -1
|
|
// loop: (target of continue)
|
|
// index++
|
|
// if index < length goto body else done
|
|
// body:
|
|
// k = index
|
|
// v = x[index]
|
|
// ...body...
|
|
// jump loop
|
|
// done: (target of break)
|
|
|
|
// Determine number of iterations.
|
|
var length Value
|
|
if arr, ok := deref(x.Type()).Underlying().(*types.Array); ok {
|
|
// For array or *array, the number of iterations is
|
|
// known statically thanks to the type. We avoid a
|
|
// data dependence upon x, permitting later dead-code
|
|
// elimination if x is pure, static unrolling, etc.
|
|
// Ranging over a nil *array may have >0 iterations.
|
|
// We still generate code for x, in case it has effects.
|
|
length = intConst(arr.Len())
|
|
} else {
|
|
// length = len(x).
|
|
var c Call
|
|
c.Call.Value = makeLen(x.Type())
|
|
c.Call.Args = []Value{x}
|
|
c.setType(tInt)
|
|
length = fn.emit(&c)
|
|
}
|
|
|
|
index := fn.addLocal(tInt, token.NoPos)
|
|
emitStore(fn, index, intConst(-1), pos)
|
|
|
|
loop = fn.newBasicBlock("rangeindex.loop")
|
|
emitJump(fn, loop)
|
|
fn.currentBlock = loop
|
|
|
|
incr := &BinOp{
|
|
Op: token.ADD,
|
|
X: emitLoad(fn, index),
|
|
Y: vOne,
|
|
}
|
|
incr.setType(tInt)
|
|
emitStore(fn, index, fn.emit(incr), pos)
|
|
|
|
body := fn.newBasicBlock("rangeindex.body")
|
|
done = fn.newBasicBlock("rangeindex.done")
|
|
emitIf(fn, emitCompare(fn, token.LSS, incr, length, token.NoPos), body, done)
|
|
fn.currentBlock = body
|
|
|
|
k = emitLoad(fn, index)
|
|
if tv != nil {
|
|
switch t := x.Type().Underlying().(type) {
|
|
case *types.Array:
|
|
instr := &Index{
|
|
X: x,
|
|
Index: k,
|
|
}
|
|
instr.setType(t.Elem())
|
|
v = fn.emit(instr)
|
|
|
|
case *types.Pointer: // *array
|
|
instr := &IndexAddr{
|
|
X: x,
|
|
Index: k,
|
|
}
|
|
instr.setType(types.NewPointer(t.Elem().Underlying().(*types.Array).Elem()))
|
|
v = emitLoad(fn, fn.emit(instr))
|
|
|
|
case *types.Slice:
|
|
instr := &IndexAddr{
|
|
X: x,
|
|
Index: k,
|
|
}
|
|
instr.setType(types.NewPointer(t.Elem()))
|
|
v = emitLoad(fn, fn.emit(instr))
|
|
|
|
default:
|
|
panic("rangeIndexed x:" + t.String())
|
|
}
|
|
}
|
|
return
|
|
}
|
|
|
|
// rangeIter emits to fn the header for a loop using
|
|
// Range/Next/Extract to iterate over map or string value x.
|
|
// tk and tv are the types of the key/value results k and v, or nil
|
|
// if the respective component is not wanted.
|
|
//
|
|
func (b *builder) rangeIter(fn *Function, x Value, tk, tv types.Type, pos token.Pos) (k, v Value, loop, done *BasicBlock) {
|
|
//
|
|
// it = range x
|
|
// loop: (target of continue)
|
|
// okv = next it (ok, key, value)
|
|
// ok = extract okv #0
|
|
// if ok goto body else done
|
|
// body:
|
|
// k = extract okv #1
|
|
// v = extract okv #2
|
|
// ...body...
|
|
// jump loop
|
|
// done: (target of break)
|
|
//
|
|
|
|
if tk == nil {
|
|
tk = tInvalid
|
|
}
|
|
if tv == nil {
|
|
tv = tInvalid
|
|
}
|
|
|
|
rng := &Range{X: x}
|
|
rng.setPos(pos)
|
|
rng.setType(tRangeIter)
|
|
it := fn.emit(rng)
|
|
|
|
loop = fn.newBasicBlock("rangeiter.loop")
|
|
emitJump(fn, loop)
|
|
fn.currentBlock = loop
|
|
|
|
_, isString := x.Type().Underlying().(*types.Basic)
|
|
|
|
okv := &Next{
|
|
Iter: it,
|
|
IsString: isString,
|
|
}
|
|
okv.setType(types.NewTuple(
|
|
varOk,
|
|
newVar("k", tk),
|
|
newVar("v", tv),
|
|
))
|
|
fn.emit(okv)
|
|
|
|
body := fn.newBasicBlock("rangeiter.body")
|
|
done = fn.newBasicBlock("rangeiter.done")
|
|
emitIf(fn, emitExtract(fn, okv, 0), body, done)
|
|
fn.currentBlock = body
|
|
|
|
if tk != tInvalid {
|
|
k = emitExtract(fn, okv, 1)
|
|
}
|
|
if tv != tInvalid {
|
|
v = emitExtract(fn, okv, 2)
|
|
}
|
|
return
|
|
}
|
|
|
|
// rangeChan emits to fn the header for a loop that receives from
|
|
// channel x until it fails.
|
|
// tk is the channel's element type, or nil if the k result is
|
|
// not wanted
|
|
// pos is the position of the '=' or ':=' token.
|
|
//
|
|
func (b *builder) rangeChan(fn *Function, x Value, tk types.Type, pos token.Pos) (k Value, loop, done *BasicBlock) {
|
|
//
|
|
// loop: (target of continue)
|
|
// ko = <-x (key, ok)
|
|
// ok = extract ko #1
|
|
// if ok goto body else done
|
|
// body:
|
|
// k = extract ko #0
|
|
// ...
|
|
// goto loop
|
|
// done: (target of break)
|
|
|
|
loop = fn.newBasicBlock("rangechan.loop")
|
|
emitJump(fn, loop)
|
|
fn.currentBlock = loop
|
|
recv := &UnOp{
|
|
Op: token.ARROW,
|
|
X: x,
|
|
CommaOk: true,
|
|
}
|
|
recv.setPos(pos)
|
|
recv.setType(types.NewTuple(
|
|
newVar("k", x.Type().Underlying().(*types.Chan).Elem()),
|
|
varOk,
|
|
))
|
|
ko := fn.emit(recv)
|
|
body := fn.newBasicBlock("rangechan.body")
|
|
done = fn.newBasicBlock("rangechan.done")
|
|
emitIf(fn, emitExtract(fn, ko, 1), body, done)
|
|
fn.currentBlock = body
|
|
if tk != nil {
|
|
k = emitExtract(fn, ko, 0)
|
|
}
|
|
return
|
|
}
|
|
|
|
// rangeStmt emits to fn code for the range statement s, optionally
|
|
// labelled by label.
|
|
//
|
|
func (b *builder) rangeStmt(fn *Function, s *ast.RangeStmt, label *lblock) {
|
|
var tk, tv types.Type
|
|
if s.Key != nil && !isBlankIdent(s.Key) {
|
|
tk = fn.Pkg.typeOf(s.Key)
|
|
}
|
|
if s.Value != nil && !isBlankIdent(s.Value) {
|
|
tv = fn.Pkg.typeOf(s.Value)
|
|
}
|
|
|
|
// If iteration variables are defined (:=), this
|
|
// occurs once outside the loop.
|
|
//
|
|
// Unlike a short variable declaration, a RangeStmt
|
|
// using := never redeclares an existing variable; it
|
|
// always creates a new one.
|
|
if s.Tok == token.DEFINE {
|
|
if tk != nil {
|
|
fn.addLocalForIdent(s.Key.(*ast.Ident))
|
|
}
|
|
if tv != nil {
|
|
fn.addLocalForIdent(s.Value.(*ast.Ident))
|
|
}
|
|
}
|
|
|
|
x := b.expr(fn, s.X)
|
|
|
|
var k, v Value
|
|
var loop, done *BasicBlock
|
|
switch rt := x.Type().Underlying().(type) {
|
|
case *types.Slice, *types.Array, *types.Pointer: // *array
|
|
k, v, loop, done = b.rangeIndexed(fn, x, tv, s.For)
|
|
|
|
case *types.Chan:
|
|
k, loop, done = b.rangeChan(fn, x, tk, s.For)
|
|
|
|
case *types.Map, *types.Basic: // string
|
|
k, v, loop, done = b.rangeIter(fn, x, tk, tv, s.For)
|
|
|
|
default:
|
|
panic("Cannot range over: " + rt.String())
|
|
}
|
|
|
|
// Evaluate both LHS expressions before we update either.
|
|
var kl, vl lvalue
|
|
if tk != nil {
|
|
kl = b.addr(fn, s.Key, false) // non-escaping
|
|
}
|
|
if tv != nil {
|
|
vl = b.addr(fn, s.Value, false) // non-escaping
|
|
}
|
|
if tk != nil {
|
|
kl.store(fn, k)
|
|
}
|
|
if tv != nil {
|
|
vl.store(fn, v)
|
|
}
|
|
|
|
if label != nil {
|
|
label._break = done
|
|
label._continue = loop
|
|
}
|
|
|
|
fn.targets = &targets{
|
|
tail: fn.targets,
|
|
_break: done,
|
|
_continue: loop,
|
|
}
|
|
b.stmt(fn, s.Body)
|
|
fn.targets = fn.targets.tail
|
|
emitJump(fn, loop) // back-edge
|
|
fn.currentBlock = done
|
|
}
|
|
|
|
// stmt lowers statement s to SSA form, emitting code to fn.
|
|
func (b *builder) stmt(fn *Function, _s ast.Stmt) {
|
|
// The label of the current statement. If non-nil, its _goto
|
|
// target is always set; its _break and _continue are set only
|
|
// within the body of switch/typeswitch/select/for/range.
|
|
// It is effectively an additional default-nil parameter of stmt().
|
|
var label *lblock
|
|
start:
|
|
switch s := _s.(type) {
|
|
case *ast.EmptyStmt:
|
|
// ignore. (Usually removed by gofmt.)
|
|
|
|
case *ast.DeclStmt: // Con, Var or Typ
|
|
d := s.Decl.(*ast.GenDecl)
|
|
if d.Tok == token.VAR {
|
|
for _, spec := range d.Specs {
|
|
if vs, ok := spec.(*ast.ValueSpec); ok {
|
|
b.localValueSpec(fn, vs)
|
|
}
|
|
}
|
|
}
|
|
|
|
case *ast.LabeledStmt:
|
|
label = fn.labelledBlock(s.Label)
|
|
emitJump(fn, label._goto)
|
|
fn.currentBlock = label._goto
|
|
_s = s.Stmt
|
|
goto start // effectively: tailcall stmt(fn, s.Stmt, label)
|
|
|
|
case *ast.ExprStmt:
|
|
b.expr(fn, s.X)
|
|
|
|
case *ast.SendStmt:
|
|
fn.emit(&Send{
|
|
Chan: b.expr(fn, s.Chan),
|
|
X: emitConv(fn, b.expr(fn, s.Value),
|
|
fn.Pkg.typeOf(s.Chan).Underlying().(*types.Chan).Elem()),
|
|
pos: s.Arrow,
|
|
})
|
|
|
|
case *ast.IncDecStmt:
|
|
op := token.ADD
|
|
if s.Tok == token.DEC {
|
|
op = token.SUB
|
|
}
|
|
loc := b.addr(fn, s.X, false)
|
|
b.assignOp(fn, loc, NewConst(constant.MakeInt64(1), loc.typ()), op, s.Pos())
|
|
|
|
case *ast.AssignStmt:
|
|
switch s.Tok {
|
|
case token.ASSIGN, token.DEFINE:
|
|
b.assignStmt(fn, s.Lhs, s.Rhs, s.Tok == token.DEFINE)
|
|
|
|
default: // +=, etc.
|
|
op := s.Tok + token.ADD - token.ADD_ASSIGN
|
|
b.assignOp(fn, b.addr(fn, s.Lhs[0], false), b.expr(fn, s.Rhs[0]), op, s.Pos())
|
|
}
|
|
|
|
case *ast.GoStmt:
|
|
// The "intrinsics" new/make/len/cap are forbidden here.
|
|
// panic is treated like an ordinary function call.
|
|
v := Go{pos: s.Go}
|
|
b.setCall(fn, s.Call, &v.Call)
|
|
fn.emit(&v)
|
|
|
|
case *ast.DeferStmt:
|
|
// The "intrinsics" new/make/len/cap are forbidden here.
|
|
// panic is treated like an ordinary function call.
|
|
v := Defer{pos: s.Defer}
|
|
b.setCall(fn, s.Call, &v.Call)
|
|
fn.emit(&v)
|
|
|
|
// A deferred call can cause recovery from panic,
|
|
// and control resumes at the Recover block.
|
|
createRecoverBlock(fn)
|
|
|
|
case *ast.ReturnStmt:
|
|
var results []Value
|
|
if len(s.Results) == 1 && fn.Signature.Results().Len() > 1 {
|
|
// Return of one expression in a multi-valued function.
|
|
tuple := b.exprN(fn, s.Results[0])
|
|
ttuple := tuple.Type().(*types.Tuple)
|
|
for i, n := 0, ttuple.Len(); i < n; i++ {
|
|
results = append(results,
|
|
emitConv(fn, emitExtract(fn, tuple, i),
|
|
fn.Signature.Results().At(i).Type()))
|
|
}
|
|
} else {
|
|
// 1:1 return, or no-arg return in non-void function.
|
|
for i, r := range s.Results {
|
|
v := emitConv(fn, b.expr(fn, r), fn.Signature.Results().At(i).Type())
|
|
results = append(results, v)
|
|
}
|
|
}
|
|
if fn.namedResults != nil {
|
|
// Function has named result parameters (NRPs).
|
|
// Perform parallel assignment of return operands to NRPs.
|
|
for i, r := range results {
|
|
emitStore(fn, fn.namedResults[i], r, s.Return)
|
|
}
|
|
}
|
|
// Run function calls deferred in this
|
|
// function when explicitly returning from it.
|
|
fn.emit(new(RunDefers))
|
|
if fn.namedResults != nil {
|
|
// Reload NRPs to form the result tuple.
|
|
results = results[:0]
|
|
for _, r := range fn.namedResults {
|
|
results = append(results, emitLoad(fn, r))
|
|
}
|
|
}
|
|
fn.emit(&Return{Results: results, pos: s.Return})
|
|
fn.currentBlock = fn.newBasicBlock("unreachable")
|
|
|
|
case *ast.BranchStmt:
|
|
var block *BasicBlock
|
|
switch s.Tok {
|
|
case token.BREAK:
|
|
if s.Label != nil {
|
|
block = fn.labelledBlock(s.Label)._break
|
|
} else {
|
|
for t := fn.targets; t != nil && block == nil; t = t.tail {
|
|
block = t._break
|
|
}
|
|
}
|
|
|
|
case token.CONTINUE:
|
|
if s.Label != nil {
|
|
block = fn.labelledBlock(s.Label)._continue
|
|
} else {
|
|
for t := fn.targets; t != nil && block == nil; t = t.tail {
|
|
block = t._continue
|
|
}
|
|
}
|
|
|
|
case token.FALLTHROUGH:
|
|
for t := fn.targets; t != nil && block == nil; t = t.tail {
|
|
block = t._fallthrough
|
|
}
|
|
|
|
case token.GOTO:
|
|
block = fn.labelledBlock(s.Label)._goto
|
|
}
|
|
emitJump(fn, block)
|
|
fn.currentBlock = fn.newBasicBlock("unreachable")
|
|
|
|
case *ast.BlockStmt:
|
|
b.stmtList(fn, s.List)
|
|
|
|
case *ast.IfStmt:
|
|
if s.Init != nil {
|
|
b.stmt(fn, s.Init)
|
|
}
|
|
then := fn.newBasicBlock("if.then")
|
|
done := fn.newBasicBlock("if.done")
|
|
els := done
|
|
if s.Else != nil {
|
|
els = fn.newBasicBlock("if.else")
|
|
}
|
|
b.cond(fn, s.Cond, then, els)
|
|
fn.currentBlock = then
|
|
b.stmt(fn, s.Body)
|
|
emitJump(fn, done)
|
|
|
|
if s.Else != nil {
|
|
fn.currentBlock = els
|
|
b.stmt(fn, s.Else)
|
|
emitJump(fn, done)
|
|
}
|
|
|
|
fn.currentBlock = done
|
|
|
|
case *ast.SwitchStmt:
|
|
b.switchStmt(fn, s, label)
|
|
|
|
case *ast.TypeSwitchStmt:
|
|
b.typeSwitchStmt(fn, s, label)
|
|
|
|
case *ast.SelectStmt:
|
|
b.selectStmt(fn, s, label)
|
|
|
|
case *ast.ForStmt:
|
|
b.forStmt(fn, s, label)
|
|
|
|
case *ast.RangeStmt:
|
|
b.rangeStmt(fn, s, label)
|
|
|
|
default:
|
|
panic(fmt.Sprintf("unexpected statement kind: %T", s))
|
|
}
|
|
}
|
|
|
|
// buildFunction builds SSA code for the body of function fn. Idempotent.
|
|
func (b *builder) buildFunction(fn *Function) {
|
|
if fn.Blocks != nil {
|
|
return // building already started
|
|
}
|
|
|
|
var recvField *ast.FieldList
|
|
var body *ast.BlockStmt
|
|
var functype *ast.FuncType
|
|
switch n := fn.syntax.(type) {
|
|
case nil:
|
|
return // not a Go source function. (Synthetic, or from object file.)
|
|
case *ast.FuncDecl:
|
|
functype = n.Type
|
|
recvField = n.Recv
|
|
body = n.Body
|
|
case *ast.FuncLit:
|
|
functype = n.Type
|
|
body = n.Body
|
|
default:
|
|
panic(n)
|
|
}
|
|
|
|
if body == nil {
|
|
// External function.
|
|
if fn.Params == nil {
|
|
// This condition ensures we add a non-empty
|
|
// params list once only, but we may attempt
|
|
// the degenerate empty case repeatedly.
|
|
// TODO(adonovan): opt: don't do that.
|
|
|
|
// We set Function.Params even though there is no body
|
|
// code to reference them. This simplifies clients.
|
|
if recv := fn.Signature.Recv(); recv != nil {
|
|
fn.addParamObj(recv)
|
|
}
|
|
params := fn.Signature.Params()
|
|
for i, n := 0, params.Len(); i < n; i++ {
|
|
fn.addParamObj(params.At(i))
|
|
}
|
|
}
|
|
return
|
|
}
|
|
if fn.Prog.mode&LogSource != 0 {
|
|
defer logStack("build function %s @ %s", fn, fn.Prog.Fset.Position(fn.pos))()
|
|
}
|
|
fn.startBody()
|
|
fn.createSyntacticParams(recvField, functype)
|
|
b.stmt(fn, body)
|
|
if cb := fn.currentBlock; cb != nil && (cb == fn.Blocks[0] || cb == fn.Recover || cb.Preds != nil) {
|
|
// Control fell off the end of the function's body block.
|
|
//
|
|
// Block optimizations eliminate the current block, if
|
|
// unreachable. It is a builder invariant that
|
|
// if this no-arg return is ill-typed for
|
|
// fn.Signature.Results, this block must be
|
|
// unreachable. The sanity checker checks this.
|
|
fn.emit(new(RunDefers))
|
|
fn.emit(new(Return))
|
|
}
|
|
fn.finishBody()
|
|
}
|
|
|
|
// buildFuncDecl builds SSA code for the function or method declared
|
|
// by decl in package pkg.
|
|
//
|
|
func (b *builder) buildFuncDecl(pkg *Package, decl *ast.FuncDecl) {
|
|
id := decl.Name
|
|
if isBlankIdent(id) {
|
|
return // discard
|
|
}
|
|
fn := pkg.values[pkg.info.Defs[id]].(*Function)
|
|
if decl.Recv == nil && id.Name == "init" {
|
|
var v Call
|
|
v.Call.Value = fn
|
|
v.setType(types.NewTuple())
|
|
pkg.init.emit(&v)
|
|
}
|
|
b.buildFunction(fn)
|
|
}
|
|
|
|
// Build calls Package.Build for each package in prog.
|
|
// Building occurs in parallel unless the BuildSerially mode flag was set.
|
|
//
|
|
// Build is intended for whole-program analysis; a typical compiler
|
|
// need only build a single package.
|
|
//
|
|
// Build is idempotent and thread-safe.
|
|
//
|
|
func (prog *Program) Build() {
|
|
var wg sync.WaitGroup
|
|
for _, p := range prog.packages {
|
|
if prog.mode&BuildSerially != 0 {
|
|
p.Build()
|
|
} else {
|
|
wg.Add(1)
|
|
go func(p *Package) {
|
|
p.Build()
|
|
wg.Done()
|
|
}(p)
|
|
}
|
|
}
|
|
wg.Wait()
|
|
}
|
|
|
|
// Build builds SSA code for all functions and vars in package p.
|
|
//
|
|
// Precondition: CreatePackage must have been called for all of p's
|
|
// direct imports (and hence its direct imports must have been
|
|
// error-free).
|
|
//
|
|
// Build is idempotent and thread-safe.
|
|
//
|
|
func (p *Package) Build() { p.buildOnce.Do(p.build) }
|
|
|
|
func (p *Package) build() {
|
|
if p.info == nil {
|
|
return // synthetic package, e.g. "testmain"
|
|
}
|
|
|
|
// Ensure we have runtime type info for all exported members.
|
|
// TODO(adonovan): ideally belongs in memberFromObject, but
|
|
// that would require package creation in topological order.
|
|
for name, mem := range p.Members {
|
|
if ast.IsExported(name) {
|
|
p.Prog.needMethodsOf(mem.Type())
|
|
}
|
|
}
|
|
if p.Prog.mode&LogSource != 0 {
|
|
defer logStack("build %s", p)()
|
|
}
|
|
init := p.init
|
|
init.startBody()
|
|
|
|
var done *BasicBlock
|
|
|
|
if p.Prog.mode&BareInits == 0 {
|
|
// Make init() skip if package is already initialized.
|
|
initguard := p.Var("init$guard")
|
|
doinit := init.newBasicBlock("init.start")
|
|
done = init.newBasicBlock("init.done")
|
|
emitIf(init, emitLoad(init, initguard), done, doinit)
|
|
init.currentBlock = doinit
|
|
emitStore(init, initguard, vTrue, token.NoPos)
|
|
|
|
// Call the init() function of each package we import.
|
|
for _, pkg := range p.Pkg.Imports() {
|
|
prereq := p.Prog.packages[pkg]
|
|
if prereq == nil {
|
|
panic(fmt.Sprintf("Package(%q).Build(): unsatisfied import: Program.CreatePackage(%q) was not called", p.Pkg.Path(), pkg.Path()))
|
|
}
|
|
var v Call
|
|
v.Call.Value = prereq.init
|
|
v.Call.pos = init.pos
|
|
v.setType(types.NewTuple())
|
|
init.emit(&v)
|
|
}
|
|
}
|
|
|
|
var b builder
|
|
|
|
// Initialize package-level vars in correct order.
|
|
for _, varinit := range p.info.InitOrder {
|
|
if init.Prog.mode&LogSource != 0 {
|
|
fmt.Fprintf(os.Stderr, "build global initializer %v @ %s\n",
|
|
varinit.Lhs, p.Prog.Fset.Position(varinit.Rhs.Pos()))
|
|
}
|
|
if len(varinit.Lhs) == 1 {
|
|
// 1:1 initialization: var x, y = a(), b()
|
|
var lval lvalue
|
|
if v := varinit.Lhs[0]; v.Name() != "_" {
|
|
lval = &address{addr: p.values[v].(*Global), pos: v.Pos()}
|
|
} else {
|
|
lval = blank{}
|
|
}
|
|
b.assign(init, lval, varinit.Rhs, true, nil)
|
|
} else {
|
|
// n:1 initialization: var x, y := f()
|
|
tuple := b.exprN(init, varinit.Rhs)
|
|
for i, v := range varinit.Lhs {
|
|
if v.Name() == "_" {
|
|
continue
|
|
}
|
|
emitStore(init, p.values[v].(*Global), emitExtract(init, tuple, i), v.Pos())
|
|
}
|
|
}
|
|
}
|
|
|
|
// Build all package-level functions, init functions
|
|
// and methods, including unreachable/blank ones.
|
|
// We build them in source order, but it's not significant.
|
|
for _, file := range p.files {
|
|
for _, decl := range file.Decls {
|
|
if decl, ok := decl.(*ast.FuncDecl); ok {
|
|
b.buildFuncDecl(p, decl)
|
|
}
|
|
}
|
|
}
|
|
|
|
// Finish up init().
|
|
if p.Prog.mode&BareInits == 0 {
|
|
emitJump(init, done)
|
|
init.currentBlock = done
|
|
}
|
|
init.emit(new(Return))
|
|
init.finishBody()
|
|
|
|
p.info = nil // We no longer need ASTs or go/types deductions.
|
|
|
|
if p.Prog.mode&SanityCheckFunctions != 0 {
|
|
sanityCheckPackage(p)
|
|
}
|
|
}
|
|
|
|
// Like ObjectOf, but panics instead of returning nil.
|
|
// Only valid during p's create and build phases.
|
|
func (p *Package) objectOf(id *ast.Ident) types.Object {
|
|
if o := p.info.ObjectOf(id); o != nil {
|
|
return o
|
|
}
|
|
panic(fmt.Sprintf("no types.Object for ast.Ident %s @ %s",
|
|
id.Name, p.Prog.Fset.Position(id.Pos())))
|
|
}
|
|
|
|
// Like TypeOf, but panics instead of returning nil.
|
|
// Only valid during p's create and build phases.
|
|
func (p *Package) typeOf(e ast.Expr) types.Type {
|
|
if T := p.info.TypeOf(e); T != nil {
|
|
return T
|
|
}
|
|
panic(fmt.Sprintf("no type for %T @ %s",
|
|
e, p.Prog.Fset.Position(e.Pos())))
|
|
}
|