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cmd/compile: use descriptors for type assertion runtime calls

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Mostly a reorganization to make further changes easier.

This reorganization will make it easier to add a cache in front
of the runtime call.

Leave the old code alone for dynamic type assertions (aka generics).

Change-Id: Ia7dcb7aeb1f63baf93584ccd792e8e31510e8aea
Reviewed-on: https://go-review.googlesource.com/c/go/+/529196
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Keith Randall <khr@google.com>
This commit is contained in:
Keith Randall 2023-09-18 10:13:18 -07:00
parent 7499257016
commit b455e239ae
9 changed files with 119 additions and 35 deletions
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28
src/cmd/compile/internal/walk/expr.go
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@ -12,6 +12,7 @@ import (
"cmd/compile/internal/base"
"cmd/compile/internal/ir"
"cmd/compile/internal/objw"
"cmd/compile/internal/reflectdata"
"cmd/compile/internal/staticdata"
"cmd/compile/internal/typecheck"
@ -724,14 +725,41 @@ func walkDotType(n *ir.TypeAssertExpr, init *ir.Nodes) ir.Node {
if !n.Type().IsInterface() && !n.X.Type().IsEmptyInterface() {
n.ITab = reflectdata.ITabAddrAt(base.Pos, n.Type(), n.X.Type())
}
if n.X.Type().IsInterface() && n.Type().IsInterface() && !n.Type().IsEmptyInterface() {
// Converting an interface to a non-empty interface. Needs a runtime call.
// Allocate an internal/abi.TypeAssert descriptor for that call.
lsym := types.LocalPkg.Lookup(fmt.Sprintf(".typeAssert.%d", typeAssertGen)).LinksymABI(obj.ABI0)
typeAssertGen++
off := 0
off = objw.SymPtr(lsym, off, reflectdata.TypeSym(n.Type()).Linksym(), 0)
off = objw.Bool(lsym, off, n.Op() == ir.ODOTTYPE2) // CanFail
off += types.PtrSize - 1
objw.Global(lsym, int32(off), obj.LOCAL|obj.NOPTR)
n.Descriptor = lsym
}
return n
}
var typeAssertGen int
// walkDynamicDotType walks an ODYNAMICDOTTYPE or ODYNAMICDOTTYPE2 node.
func walkDynamicDotType(n *ir.DynamicTypeAssertExpr, init *ir.Nodes) ir.Node {
n.X = walkExpr(n.X, init)
n.RType = walkExpr(n.RType, init)
n.ITab = walkExpr(n.ITab, init)
// Convert to non-dynamic if we can.
if n.RType != nil && n.RType.Op() == ir.OADDR {
addr := n.RType.(*ir.AddrExpr)
if addr.X.Op() == ir.OLINKSYMOFFSET {
r := ir.NewTypeAssertExpr(n.Pos(), n.X, n.Type())
if n.Op() == ir.ODYNAMICDOTTYPE2 {
r.SetOp(ir.ODOTTYPE2)
}
r.SetType(n.Type())
r.SetTypecheck(1)
return walkExpr(r, init)
}
}
return n
}