435c0d9fc8
This PR switches the Nomad repository from using govendor to Go modules for managing dependencies. Aspects of the Nomad workflow remain pretty much the same. The usual Makefile targets should continue to work as they always did. The API submodule simply defers to the parent Nomad version on the repository, keeping the semantics of API versioning that currently exists.
117 lines
2.9 KiB
Go
117 lines
2.9 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 ir
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// lvalues are the union of addressable expressions and map-index
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// expressions.
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import (
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"go/ast"
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"go/types"
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)
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// An lvalue represents an assignable location that may appear on the
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// left-hand side of an assignment. This is a generalization of a
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// pointer to permit updates to elements of maps.
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//
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type lvalue interface {
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store(fn *Function, v Value, source ast.Node) // stores v into the location
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load(fn *Function, source ast.Node) Value // loads the contents of the location
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address(fn *Function) Value // address of the location
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typ() types.Type // returns the type of the location
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}
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// An address is an lvalue represented by a true pointer.
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type address struct {
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addr Value
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expr ast.Expr // source syntax of the value (not address) [debug mode]
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}
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func (a *address) load(fn *Function, source ast.Node) Value {
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return emitLoad(fn, a.addr, source)
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}
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func (a *address) store(fn *Function, v Value, source ast.Node) {
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store := emitStore(fn, a.addr, v, source)
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if a.expr != nil {
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// store.Val is v, converted for assignability.
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emitDebugRef(fn, a.expr, store.Val, false)
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}
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}
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func (a *address) address(fn *Function) Value {
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if a.expr != nil {
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emitDebugRef(fn, a.expr, a.addr, true)
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}
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return a.addr
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}
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func (a *address) typ() types.Type {
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return deref(a.addr.Type())
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}
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// An element is an lvalue represented by m[k], the location of an
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// element of a map. These locations are not addressable
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// since pointers cannot be formed from them, but they do support
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// load() and store().
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//
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type element struct {
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m, k Value // map
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t types.Type // map element type
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}
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func (e *element) load(fn *Function, source ast.Node) Value {
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l := &MapLookup{
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X: e.m,
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Index: e.k,
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}
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l.setType(e.t)
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return fn.emit(l, source)
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}
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func (e *element) store(fn *Function, v Value, source ast.Node) {
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up := &MapUpdate{
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Map: e.m,
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Key: e.k,
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Value: emitConv(fn, v, e.t, source),
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}
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fn.emit(up, source)
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}
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func (e *element) address(fn *Function) Value {
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panic("map elements are not addressable")
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}
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func (e *element) typ() types.Type {
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return e.t
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}
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// A blank is a dummy variable whose name is "_".
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// It is not reified: loads are illegal and stores are ignored.
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//
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type blank struct{}
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func (bl blank) load(fn *Function, source ast.Node) Value {
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panic("blank.load is illegal")
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}
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func (bl blank) store(fn *Function, v Value, source ast.Node) {
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s := &BlankStore{
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Val: v,
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}
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fn.emit(s, source)
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}
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func (bl blank) address(fn *Function) Value {
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panic("blank var is not addressable")
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}
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func (bl blank) typ() types.Type {
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// This should be the type of the blank Ident; the typechecker
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// doesn't provide this yet, but fortunately, we don't need it
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// yet either.
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panic("blank.typ is unimplemented")
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}
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