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[dev.typeparams] cmd/compile: implement generic .(T) operations

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Introduce new dynamic dottype operations which take a dynamic
instead of static type to convert to.

Change-Id: I5824a1fea056fe811b1226ce059e1e8da1baa335
Reviewed-on: https://go-review.googlesource.com/c/go/+/337609
Trust: Keith Randall <khr@golang.org>
Trust: Dan Scales <danscales@google.com>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Dan Scales <danscales@google.com>
This commit is contained in:
Keith Randall 2021-07-26 17:41:02 -07:00
parent 4a47e40a14
commit f4f503e0a3
11 changed files with 209 additions and 53 deletions
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43
src/cmd/compile/internal/noder/stencil.go
View file

@ -1039,6 +1039,7 @@ func (subst *subster) checkDictionary(name *ir.Name, targs []*types.Type) (code
d.SetTypecheck(1)
d = ir.NewConvExpr(pos, ir.OCONVNOP, types.NewArray(types.Types[types.TUINTPTR], int64(len(targs))).PtrTo(), d)
d.SetTypecheck(1)
types.CheckSize(d.Type().Elem())
// Check that each type entry in the dictionary is correct.
for i, t := range targs {
@ -1079,6 +1080,7 @@ func getDictionaryEntry(pos src.XPos, dict *ir.Name, i int, size int) ir.Node {
d.SetTypecheck(1)
d = ir.NewConvExpr(pos, ir.OCONVNOP, types.NewArray(types.Types[types.TUINTPTR], int64(size)).PtrTo(), d)
d.SetTypecheck(1)
types.CheckSize(d.Type().Elem())
// Load entry i out of the dictionary.
deref := ir.NewStarExpr(pos, d)
@ -1367,7 +1369,31 @@ func (subst *subster) node(n ir.Node) ir.Node {
m = subst.convertUsingDictionary(m.Pos(), m.(*ir.ConvExpr).X, x, m.Type(), x.X.Type())
}
case ir.ODOTTYPE, ir.ODOTTYPE2:
m.SetType(subst.unshapifyTyp(m.Type()))
dt := m.(*ir.TypeAssertExpr)
var rt ir.Node
if dt.Type().IsInterface() || dt.X.Type().IsEmptyInterface() {
ix := subst.findDictType(x.Type())
assert(ix >= 0)
rt = subst.getDictionaryType(dt.Pos(), ix)
} else {
// nonempty interface to noninterface. Need an itab.
ix := -1
for i, ic := range subst.info.gfInfo.itabConvs {
if ic == x {
ix = subst.info.startItabConv + i
break
}
}
assert(ix >= 0)
rt = getDictionaryEntry(dt.Pos(), subst.info.dictParam, ix, subst.info.dictLen)
}
op := ir.ODYNAMICDOTTYPE
if x.Op() == ir.ODOTTYPE2 {
op = ir.ODYNAMICDOTTYPE2
}
m = ir.NewDynamicTypeAssertExpr(dt.Pos(), op, dt.X, rt)
m.SetType(dt.Type())
m.SetTypecheck(1)
case ir.OMETHEXPR:
se := m.(*ir.SelectorExpr)
@ -1696,7 +1722,8 @@ func (g *irgen) finalizeSyms() {
// Emit an entry for each itab
for _, n := range info.itabConvs {
var srctype, dsttype *types.Type
if n.Op() == ir.OXDOT {
switch n.Op() {
case ir.OXDOT:
se := n.(*ir.SelectorExpr)
srctype = subst.Typ(se.X.Type())
dsttype = subst.Typ(se.X.Type().Bound())
@ -1712,10 +1739,14 @@ func (g *irgen) finalizeSyms() {
}
}
assert(found)
} else {
assert(n.Op() == ir.OCONVIFACE)
case ir.ODOTTYPE, ir.ODOTTYPE2:
srctype = subst.Typ(n.(*ir.TypeAssertExpr).Type())
dsttype = subst.Typ(n.(*ir.TypeAssertExpr).X.Type())
case ir.OCONVIFACE:
srctype = subst.Typ(n.(*ir.ConvExpr).X.Type())
dsttype = subst.Typ(n.Type())
default:
base.Fatalf("itab entry with unknown op %s", n.Op())
}
itabLsym := reflectdata.ITabLsym(srctype, dsttype)
d.off = objw.SymPtr(lsym, d.off, itabLsym, 0)
@ -1859,6 +1890,10 @@ func (g *irgen) getGfInfo(gn *ir.Name) *gfInfo {
infoPrint(" Itab for interface conv: %v\n", n)
info.itabConvs = append(info.itabConvs, n)
}
if (n.Op() == ir.ODOTTYPE || n.Op() == ir.ODOTTYPE2) && !n.(*ir.TypeAssertExpr).Type().IsInterface() && !n.(*ir.TypeAssertExpr).X.Type().IsEmptyInterface() {
infoPrint(" Itab for dot type: %v\n", n)
info.itabConvs = append(info.itabConvs, n)
}
if n.Op() == ir.OCLOSURE {
// Visit the closure body and add all relevant entries to the
// dictionary of the outer function (closure will just use