cmd/compile: simplify assert{E,I}2I{,2} calling conventions

This CL rebases CL 273694 on top of master with @mdempsky's permission.

For assertE2I and assertI2I, there's no need to pass through the
interface's data pointer: it's always going to come back unmodified.

For assertE2I2 and assertI2I2, there's no need for an extra bool
result parameter: it's redundant with testing the returned interface
value for nil.

Change-Id: Ic92d4409ad381952f875d3d74b8cf11c32702fa6
Reviewed-on: https://go-review.googlesource.com/c/go/+/292892
Trust: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

5 files changed, 34 insertions, 39 deletions

diff --git a/src/cmd/compile/internal/ssagen/ssa.go b/src/cmd/compile/internal/ssagen/ssa.go
index 6b1ddebd32..e13ca90d33 100644
--- a/src/cmd/compile/internal/ssagen/ssa.go
+++ b/src/cmd/compile/internal/ssagen/ssa.go
@@ -6075,18 +6075,23 @@ func (s *state) dottype(n *ir.TypeAssertExpr, commaok bool) (res, resok *ssa.Val
 		if base.Debug.TypeAssert > 0 {
 			base.WarnfAt(n.Pos(), "type assertion not inlined")
 		}
-		if n.X.Type().IsEmptyInterface() {
-			if commaok {
-				call := s.rtcall(ir.Syms.AssertE2I2, true, []*types.Type{n.Type(), types.Types[types.TBOOL]}, target, iface)
-				return call[0], call[1]
+		if !commaok {
+			fn := ir.Syms.AssertI2I
+			if n.X.Type().IsEmptyInterface() {
+				fn = ir.Syms.AssertE2I
 			}
-			return s.rtcall(ir.Syms.AssertE2I, true, []*types.Type{n.Type()}, target, iface)[0], nil
+			data := s.newValue1(ssa.OpIData, types.Types[types.TUNSAFEPTR], iface)
+			tab := s.newValue1(ssa.OpITab, byteptr, iface)
+			tab = s.rtcall(fn, true, []*types.Type{byteptr}, target, tab)[0]
+			return s.newValue2(ssa.OpIMake, n.Type(), tab, data), nil
 		}
-		if commaok {
-			call := s.rtcall(ir.Syms.AssertI2I2, true, []*types.Type{n.Type(), types.Types[types.TBOOL]}, target, iface)
-			return call[0], call[1]
+		fn := ir.Syms.AssertI2I2
+		if n.X.Type().IsEmptyInterface() {
+			fn = ir.Syms.AssertE2I2
 		}
-		return s.rtcall(ir.Syms.AssertI2I, true, []*types.Type{n.Type()}, target, iface)[0], nil
+		res = s.rtcall(fn, true, []*types.Type{n.Type()}, target, iface)[0]
+		resok = s.newValue2(ssa.OpNeqInter, types.Types[types.TBOOL], res, s.constInterface(n.Type()))
+		return
 	}
 
 	if base.Debug.TypeAssert > 0 {
diff --git a/src/cmd/compile/internal/typecheck/builtin.go b/src/cmd/compile/internal/typecheck/builtin.go
index b095a014f0..3c7776d9ae 100644
--- a/src/cmd/compile/internal/typecheck/builtin.go
+++ b/src/cmd/compile/internal/typecheck/builtin.go
@@ -80,10 +80,10 @@ var runtimeDecls = [...]struct {
 	{"convT2Enoptr", funcTag, 59},
 	{"convT2I", funcTag, 59},
 	{"convT2Inoptr", funcTag, 59},
-	{"assertE2I", funcTag, 57},
-	{"assertE2I2", funcTag, 60},
-	{"assertI2I", funcTag, 57},
-	{"assertI2I2", funcTag, 60},
+	{"assertE2I", funcTag, 60},
+	{"assertE2I2", funcTag, 57},
+	{"assertI2I", funcTag, 60},
+	{"assertI2I2", funcTag, 57},
 	{"panicdottypeE", funcTag, 61},
 	{"panicdottypeI", funcTag, 61},
 	{"panicnildottype", funcTag, 62},
@@ -280,7 +280,7 @@ func runtimeTypes() []*types.Type {
 	typs[57] = newSig(params(typs[1], typs[2]), params(typs[2]))
 	typs[58] = newSig(params(typs[2]), params(typs[7]))
 	typs[59] = newSig(params(typs[1], typs[3]), params(typs[2]))
-	typs[60] = newSig(params(typs[1], typs[2]), params(typs[2], typs[6]))
+	typs[60] = newSig(params(typs[1], typs[1]), params(typs[1]))
 	typs[61] = newSig(params(typs[1], typs[1], typs[1]), nil)
 	typs[62] = newSig(params(typs[1]), nil)
 	typs[63] = types.NewPtr(typs[5])
diff --git a/src/cmd/compile/internal/typecheck/builtin/runtime.go b/src/cmd/compile/internal/typecheck/builtin/runtime.go
index ad82a9b349..d5e00afcf8 100644
--- a/src/cmd/compile/internal/typecheck/builtin/runtime.go
+++ b/src/cmd/compile/internal/typecheck/builtin/runtime.go
@@ -101,10 +101,10 @@ func convT2I(tab *byte, elem *any) (ret any)
 func convT2Inoptr(tab *byte, elem *any) (ret any)
 
 // interface type assertions x.(T)
-func assertE2I(typ *byte, iface any) (ret any)
-func assertE2I2(typ *byte, iface any) (ret any, b bool)
-func assertI2I(typ *byte, iface any) (ret any)
-func assertI2I2(typ *byte, iface any) (ret any, b bool)
+func assertE2I(inter *byte, typ *byte) *byte
+func assertE2I2(inter *byte, eface any) (ret any)
+func assertI2I(inter *byte, tab *byte) *byte
+func assertI2I2(inter *byte, iface any) (ret any)
 func panicdottypeE(have, want, iface *byte)
 func panicdottypeI(have, want, iface *byte)
 func panicnildottype(want *byte)
diff --git a/src/runtime/iface.go b/src/runtime/iface.go
index 0504b89363..02b18dabff 100644
--- a/src/runtime/iface.go
+++ b/src/runtime/iface.go
@@ -447,23 +447,18 @@ func convI2I(inter *interfacetype, i iface) (r iface) {
 	return
 }
 
-func assertI2I(inter *interfacetype, i iface) (r iface) {
-	tab := i.tab
+func assertI2I(inter *interfacetype, tab *itab) *itab {
 	if tab == nil {
 		// explicit conversions require non-nil interface value.
 		panic(&TypeAssertionError{nil, nil, &inter.typ, ""})
 	}
 	if tab.inter == inter {
-		r.tab = tab
-		r.data = i.data
-		return
+		return tab
 	}
-	r.tab = getitab(inter, tab._type, false)
-	r.data = i.data
-	return
+	return getitab(inter, tab._type, false)
 }
 
-func assertI2I2(inter *interfacetype, i iface) (r iface, b bool) {
+func assertI2I2(inter *interfacetype, i iface) (r iface) {
 	tab := i.tab
 	if tab == nil {
 		return
@@ -476,22 +471,18 @@ func assertI2I2(inter *interfacetype, i iface) (r iface, b bool) {
 	}
 	r.tab = tab
 	r.data = i.data
-	b = true
 	return
 }
 
-func assertE2I(inter *interfacetype, e eface) (r iface) {
-	t := e._type
+func assertE2I(inter *interfacetype, t *_type) *itab {
 	if t == nil {
 		// explicit conversions require non-nil interface value.
 		panic(&TypeAssertionError{nil, nil, &inter.typ, ""})
 	}
-	r.tab = getitab(inter, t, false)
-	r.data = e.data
-	return
+	return getitab(inter, t, false)
 }
 
-func assertE2I2(inter *interfacetype, e eface) (r iface, b bool) {
+func assertE2I2(inter *interfacetype, e eface) (r iface) {
 	t := e._type
 	if t == nil {
 		return
@@ -502,18 +493,17 @@ func assertE2I2(inter *interfacetype, e eface) (r iface, b bool) {
 	}
 	r.tab = tab
 	r.data = e.data
-	b = true
 	return
 }
 
 //go:linkname reflect_ifaceE2I reflect.ifaceE2I
 func reflect_ifaceE2I(inter *interfacetype, e eface, dst *iface) {
-	*dst = assertE2I(inter, e)
+	*dst = iface{assertE2I(inter, e._type), e.data}
 }
 
 //go:linkname reflectlite_ifaceE2I internal/reflectlite.ifaceE2I
 func reflectlite_ifaceE2I(inter *interfacetype, e eface, dst *iface) {
-	*dst = assertE2I(inter, e)
+	*dst = iface{assertE2I(inter, e._type), e.data}
 }
 
 func iterate_itabs(fn func(*itab)) {
diff --git a/src/runtime/mfinal.go b/src/runtime/mfinal.go
index 7d0313be12..e92ec80e3c 100644
--- a/src/runtime/mfinal.go
+++ b/src/runtime/mfinal.go
@@ -214,7 +214,7 @@ func runfinq() {
 					if len(ityp.mhdr) != 0 {
 						// convert to interface with methods
 						// this conversion is guaranteed to succeed - we checked in SetFinalizer
-						*(*iface)(frame) = assertE2I(ityp, *(*eface)(frame))
+						(*iface)(frame).tab = assertE2I(ityp, (*eface)(frame)._type)
 					}
 				default:
 					throw("bad kind in runfinq")
@@ -403,7 +403,7 @@ func SetFinalizer(obj interface{}, finalizer interface{}) {
 			// ok - satisfies empty interface
 			goto okarg
 		}
-		if _, ok := assertE2I2(ityp, *efaceOf(&obj)); ok {
+		if iface := assertE2I2(ityp, *efaceOf(&obj)); iface.tab != nil {
 			goto okarg
 		}
 	}