// logical generates code for || and && operators.
func (c *compiler) logical(op scan.Type, e *ast.BinaryExpr, lv *arch.LV) *node {
l := []*ast.BinaryExpr{e}
for x := e.X; ; {
y, ok := x.(*ast.BinaryExpr)
if !ok || y.Op.Type != op {
break
}
l = append(l, y)
x = y.X
}
var lx arch.LV
n := c.exprInternal(l[len(l)-1].X, lv)
for i := len(l) - 1; i >= 0; i-- {
var lv2 arch.LV
if lx.Addr == 0 {
lx.Addr = c.cg.Label()
}
n = c.rvalue(n, lv)
n2 := c.exprInternal(l[i].Y, &lv2)
n2 = c.rvalue(n2, &lv2)
if op == scan.Lor {
n = newNode(opBrTrue, &lx, nil, n, n2)
} else {
n = newNode(opBrFalse, &lx, nil, n, n2)
}
}
n = newNode(opLab, &lx, nil, n, nil)
n = newNode(opBool, nil, nil, n, nil)
lv.Type = types.Typ[types.Int]
lv.Addressable = false
return n
}
// ident generates code for an identifier by loading it into the accumulator.
func (c *compiler) ident(e *ast.Ident, lv *arch.LV, tv types.TypeAndValue) *node {
lv.Ident = true
lv.Type = tv.Type.Underlying()
lv.Name = e.Name
_, isFunc := tv.Type.(*types.Signature)
if isFunc {
if x, ok := c.Uses[e]; ok {
switch x := x.(type) {
case *types.Func:
lv.Storage = x.Storage()
return newNode(opAddr, lv, nil, nil, nil)
case *types.Fwrd:
return newNode(opAddr, lv, nil, nil, nil)
}
}
}
v, found := c.variable(e, c.Uses)
if !found {
lv.Ident = false
return nil
}
s, found := c.symbol(v)
if !found {
lv.Ident = false
return nil
}
_, isRecord := lv.Type.(*types.Record)
// arrays decay to pointers, so we need to get the original type
// because the type and value by the typechecker is recorded as a pointer
array, isArray := v.Type().(*types.Array)
lv.Addr = s.Addr
lv.Value = s.Value
lv.Storage = v.Storage()
switch {
// constants
case tv.Value != nil:
lv.Value = tv.Value
return newNode(opLit, lv, nil, nil, nil)
case isArray:
lv.Type = types.NewPointer(array.Elem(), nil)
return newNode(opAddr, lv, nil, nil, nil)
case isRecord:
lv.Ident = false
return newNode(opAddr, lv, nil, nil, nil)
// variable that a integer or a pointer
default:
lv.Addressable = true
return newNode(opIdent, lv, nil, nil, nil)
}
}
// condExpr generates code for ? and : operators.
func (c *compiler) condExpr(e *ast.CondExpr, lv *arch.LV) *node {
l := []*ast.CondExpr{e}
for x := e.Cond; ; {
y, ok := x.(*ast.CondExpr)
if !ok {
break
}
l = append(l, y)
x = y.Cond
}
var lx arch.LV
var l2 int
var typ types.Type
n := c.exprInternal(l[len(l)-1].Cond, lv)
for i := len(l) - 1; i >= 0; i-- {
var lv2 arch.LV
n = c.rvalue(n, lv)
l1 := c.cg.Label()
if l2 == 0 {
l2 = c.cg.Label()
}
n2 := c.exprInternal(l[i].X, &lv2)
n2 = c.rvalue(n2, &lv2)
lx.Addr = l1
n = newNode(opBrFalse, &lx, nil, n, n2)
if typ == nil {
typ = lv2.Type
}
n2 = c.exprInternal(l[i].Y, &lv2)
n2 = c.rvalue(n2, &lv2)
n = newNode(opGlue, nil, nil, n, n2)
}
lx.Addr = l2
n = newNode(opIfElse, &lx, nil, n, nil)
lv.Type = typ
lv.Addressable = false
return n
}
// defineLocal defines a variable at a function scope.
func (c *compiler) defineLocal(v *types.Var, lv *arch.LV) {
val := c.cg.Label()
lv.Addr = val
c.cg.Data()
intSize := c.cg.Int()
ptrSize := c.cg.Pointer()
size := 1
typ := v.Type().Underlying()
prim := primType(typ)
array, isArray := typ.(*types.Array)
isRecord := isRecord(typ, true)
if isArray {
size = int(array.Len())
}
init := 0
if x := v.Value(); x != nil {
init, _ = strconv.Atoi(x.String())
}
if !isArray && !isRecord {
c.cg.Lab(val)
}
switch {
case isRecord:
c.cg.BSS(c.cg.Labname(val), c.cg.Sizeof(typ), true)
case prim == types.Typ[types.Char]:
if isArray {
c.cg.BSS(c.cg.Labname(val), size, true)
} else {
c.cg.Defb(init)
c.cg.Align(1, intSize)
}
case prim == types.Typ[types.Int]:
if isArray {
c.cg.BSS(c.cg.Labname(val), size*intSize, true)
} else {
c.cg.Defw(init)
}
default:
if isArray {
c.cg.BSS(c.cg.Labname(val), size*ptrSize, true)
} else {
c.cg.Defp(init)
}
}
}
// exprInternal is the main function for generating code by figuring
// out what kind of expression it is.
func (c *compiler) exprInternal(e ast.Expr, lv *arch.LV) *node {
lv.Ident = false
pos := e.Span().Start
tv, found := c.typAndValue(e)
if !found {
return nil
}
// for constants we can just get the value right away
if tv.Value != nil {
lv.Type = tv.Type
lv.Value = tv.Value
switch tv.Type {
case types.Typ[types.UntypedString]:
str, err := strconv.Unquote(tv.Value.String())
if err != nil {
c.errorf(pos, "invalid constant %v: %v", tv.Value, err)
}
c.cg.Data()
lab := c.cg.Label()
c.cg.Lab(lab)
c.cg.Defs(str)
c.cg.Defb(0)
c.cg.Align(len(str)+1, c.cg.Int())
lv.Addr = lab
return newNode(opLdlab, lv, nil, nil, nil)
default:
return newNode(opLit, lv, nil, nil, nil)
}
}
switch e := e.(type) {
case *ast.BinaryExpr:
return c.binaryExpr(e, lv)
case *ast.UnaryExpr:
return c.unaryExpr(e, lv)
case *ast.SizeofExpr:
return c.sizeofExpr(e, lv, tv)
case *ast.StarExpr:
return c.starExpr(e, lv)
case *ast.CallExpr:
return c.callExpr(e, lv)
case *ast.Ident:
return c.ident(e, lv, tv)
case *ast.ParenExpr:
return c.exprInternal(e.X, lv)
case *ast.IndexExpr:
return c.indexExpr(e, lv)
case *ast.SelectorExpr:
return c.selectorExpr(e, lv)
case *ast.CondExpr:
return c.condExpr(e, lv)
case *ast.CastExpr:
return c.castExpr(e, lv, tv)
case *ast.BasicType:
lv.Type = tv.Type
default:
c.errorf(pos, "invalid expression: %T", e)
}
return nil
}