[dev.typeparams] cmd/compile: introduce OCONVIDATA op

This operation computes just the data field needed to put its argument
into an interface. Used by generics because we produce the type field
of an interface using dictionaries (instead of statically).

With this operation defined, we can now assert that shape types
are never marked as used in interfaces (the only previous use
was IDATA(CONVIFACE(t))).

Change-Id: Idb1eb5f3b238285cb99413d382599c0621b7681a
Reviewed-on: https://go-review.googlesource.com/c/go/+/337109
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>

13 files changed, 161 insertions, 145 deletions

diff --git a/src/cmd/compile/internal/escape/expr.go b/src/cmd/compile/internal/escape/expr.go
index 60b44fe0aa..b7423e114a 100644
--- a/src/cmd/compile/internal/escape/expr.go
+++ b/src/cmd/compile/internal/escape/expr.go
@@ -109,7 +109,7 @@ func (e *escape) exprSkipInit(k hole, n ir.Node) {
 		} else {
 			e.expr(k, n.X)
 		}
-	case ir.OCONVIFACE:
+	case ir.OCONVIFACE, ir.OCONVIDATA:
 		n := n.(*ir.ConvExpr)
 		if !n.X.Type().IsInterface() && !types.IsDirectIface(n.X.Type()) {
 			k = e.spill(k, n)
diff --git a/src/cmd/compile/internal/ir/expr.go b/src/cmd/compile/internal/ir/expr.go
index 09d6d87f06..86323e6b8f 100644
--- a/src/cmd/compile/internal/ir/expr.go
+++ b/src/cmd/compile/internal/ir/expr.go
@@ -270,7 +270,7 @@ func (n *ConvExpr) SetOp(op Op) {
 	switch op {
 	default:
 		panic(n.no("SetOp " + op.String()))
-	case OCONV, OCONVIFACE, OCONVNOP, OBYTES2STR, OBYTES2STRTMP, ORUNES2STR, OSTR2BYTES, OSTR2BYTESTMP, OSTR2RUNES, ORUNESTR, OSLICE2ARRPTR:
+	case OCONV, OCONVIFACE, OCONVIDATA, OCONVNOP, OBYTES2STR, OBYTES2STRTMP, ORUNES2STR, OSTR2BYTES, OSTR2BYTESTMP, OSTR2RUNES, ORUNESTR, OSLICE2ARRPTR:
 		n.op = op
 	}
 }
diff --git a/src/cmd/compile/internal/ir/fmt.go b/src/cmd/compile/internal/ir/fmt.go
index e8dd9df69d..3c5a928590 100644
--- a/src/cmd/compile/internal/ir/fmt.go
+++ b/src/cmd/compile/internal/ir/fmt.go
@@ -185,6 +185,7 @@ var OpPrec = []int{
 	OCLOSE:         8,
 	OCOMPLIT:       8,
 	OCONVIFACE:     8,
+	OCONVIDATA:     8,
 	OCONVNOP:       8,
 	OCONV:          8,
 	OCOPY:          8,
@@ -546,7 +547,7 @@ func exprFmt(n Node, s fmt.State, prec int) {
 				n = nn.X
 				continue
 			}
-		case OCONV, OCONVNOP, OCONVIFACE:
+		case OCONV, OCONVNOP, OCONVIFACE, OCONVIDATA:
 			nn := nn.(*ConvExpr)
 			if nn.Implicit() {
 				n = nn.X
@@ -813,6 +814,7 @@ func exprFmt(n Node, s fmt.State, prec int) {
 
 	case OCONV,
 		OCONVIFACE,
+		OCONVIDATA,
 		OCONVNOP,
 		OBYTES2STR,
 		ORUNES2STR,
diff --git a/src/cmd/compile/internal/ir/node.go b/src/cmd/compile/internal/ir/node.go
index f6eae58b04..0fbc867c1d 100644
--- a/src/cmd/compile/internal/ir/node.go
+++ b/src/cmd/compile/internal/ir/node.go
@@ -170,6 +170,7 @@ const (
 	OPTRLIT    // &X (X is composite literal)
 	OCONV      // Type(X) (type conversion)
 	OCONVIFACE // Type(X) (type conversion, to interface)
+	OCONVIDATA // Builds a data word to store X in an interface. Equivalent to IDATA(CONVIFACE(X)). Is an ir.ConvExpr.
 	OCONVNOP   // Type(X) (type conversion, no effect)
 	OCOPY      // copy(X, Y)
 	ODCL       // var X (declares X of type X.Type)
diff --git a/src/cmd/compile/internal/ir/op_string.go b/src/cmd/compile/internal/ir/op_string.go
index 05a37a60b1..0235d5eab3 100644
--- a/src/cmd/compile/internal/ir/op_string.go
+++ b/src/cmd/compile/internal/ir/op_string.go
@@ -52,125 +52,126 @@ func _() {
 	_ = x[OPTRLIT-41]
 	_ = x[OCONV-42]
 	_ = x[OCONVIFACE-43]
-	_ = x[OCONVNOP-44]
-	_ = x[OCOPY-45]
-	_ = x[ODCL-46]
-	_ = x[ODCLFUNC-47]
-	_ = x[ODCLCONST-48]
-	_ = x[ODCLTYPE-49]
-	_ = x[ODELETE-50]
-	_ = x[ODOT-51]
-	_ = x[ODOTPTR-52]
-	_ = x[ODOTMETH-53]
-	_ = x[ODOTINTER-54]
-	_ = x[OXDOT-55]
-	_ = x[ODOTTYPE-56]
-	_ = x[ODOTTYPE2-57]
-	_ = x[OEQ-58]
-	_ = x[ONE-59]
-	_ = x[OLT-60]
-	_ = x[OLE-61]
-	_ = x[OGE-62]
-	_ = x[OGT-63]
-	_ = x[ODEREF-64]
-	_ = x[OINDEX-65]
-	_ = x[OINDEXMAP-66]
-	_ = x[OKEY-67]
-	_ = x[OSTRUCTKEY-68]
-	_ = x[OLEN-69]
-	_ = x[OMAKE-70]
-	_ = x[OMAKECHAN-71]
-	_ = x[OMAKEMAP-72]
-	_ = x[OMAKESLICE-73]
-	_ = x[OMAKESLICECOPY-74]
-	_ = x[OMUL-75]
-	_ = x[ODIV-76]
-	_ = x[OMOD-77]
-	_ = x[OLSH-78]
-	_ = x[ORSH-79]
-	_ = x[OAND-80]
-	_ = x[OANDNOT-81]
-	_ = x[ONEW-82]
-	_ = x[ONOT-83]
-	_ = x[OBITNOT-84]
-	_ = x[OPLUS-85]
-	_ = x[ONEG-86]
-	_ = x[OOROR-87]
-	_ = x[OPANIC-88]
-	_ = x[OPRINT-89]
-	_ = x[OPRINTN-90]
-	_ = x[OPAREN-91]
-	_ = x[OSEND-92]
-	_ = x[OSLICE-93]
-	_ = x[OSLICEARR-94]
-	_ = x[OSLICESTR-95]
-	_ = x[OSLICE3-96]
-	_ = x[OSLICE3ARR-97]
-	_ = x[OSLICEHEADER-98]
-	_ = x[ORECOVER-99]
-	_ = x[ORECOVERFP-100]
-	_ = x[ORECV-101]
-	_ = x[ORUNESTR-102]
-	_ = x[OSELRECV2-103]
-	_ = x[OIOTA-104]
-	_ = x[OREAL-105]
-	_ = x[OIMAG-106]
-	_ = x[OCOMPLEX-107]
-	_ = x[OALIGNOF-108]
-	_ = x[OOFFSETOF-109]
-	_ = x[OSIZEOF-110]
-	_ = x[OUNSAFEADD-111]
-	_ = x[OUNSAFESLICE-112]
-	_ = x[OMETHEXPR-113]
-	_ = x[OMETHVALUE-114]
-	_ = x[OBLOCK-115]
-	_ = x[OBREAK-116]
-	_ = x[OCASE-117]
-	_ = x[OCONTINUE-118]
-	_ = x[ODEFER-119]
-	_ = x[OFALL-120]
-	_ = x[OFOR-121]
-	_ = x[OFORUNTIL-122]
-	_ = x[OGOTO-123]
-	_ = x[OIF-124]
-	_ = x[OLABEL-125]
-	_ = x[OGO-126]
-	_ = x[ORANGE-127]
-	_ = x[ORETURN-128]
-	_ = x[OSELECT-129]
-	_ = x[OSWITCH-130]
-	_ = x[OTYPESW-131]
-	_ = x[OFUNCINST-132]
-	_ = x[OTCHAN-133]
-	_ = x[OTMAP-134]
-	_ = x[OTSTRUCT-135]
-	_ = x[OTINTER-136]
-	_ = x[OTFUNC-137]
-	_ = x[OTARRAY-138]
-	_ = x[OTSLICE-139]
-	_ = x[OINLCALL-140]
-	_ = x[OEFACE-141]
-	_ = x[OITAB-142]
-	_ = x[OIDATA-143]
-	_ = x[OSPTR-144]
-	_ = x[OCFUNC-145]
-	_ = x[OCHECKNIL-146]
-	_ = x[OVARDEF-147]
-	_ = x[OVARKILL-148]
-	_ = x[OVARLIVE-149]
-	_ = x[ORESULT-150]
-	_ = x[OINLMARK-151]
-	_ = x[OLINKSYMOFFSET-152]
-	_ = x[OTAILCALL-153]
-	_ = x[OGETG-154]
-	_ = x[OGETCALLERPC-155]
-	_ = x[OGETCALLERSP-156]
-	_ = x[OEND-157]
+	_ = x[OCONVIDATA-44]
+	_ = x[OCONVNOP-45]
+	_ = x[OCOPY-46]
+	_ = x[ODCL-47]
+	_ = x[ODCLFUNC-48]
+	_ = x[ODCLCONST-49]
+	_ = x[ODCLTYPE-50]
+	_ = x[ODELETE-51]
+	_ = x[ODOT-52]
+	_ = x[ODOTPTR-53]
+	_ = x[ODOTMETH-54]
+	_ = x[ODOTINTER-55]
+	_ = x[OXDOT-56]
+	_ = x[ODOTTYPE-57]
+	_ = x[ODOTTYPE2-58]
+	_ = x[OEQ-59]
+	_ = x[ONE-60]
+	_ = x[OLT-61]
+	_ = x[OLE-62]
+	_ = x[OGE-63]
+	_ = x[OGT-64]
+	_ = x[ODEREF-65]
+	_ = x[OINDEX-66]
+	_ = x[OINDEXMAP-67]
+	_ = x[OKEY-68]
+	_ = x[OSTRUCTKEY-69]
+	_ = x[OLEN-70]
+	_ = x[OMAKE-71]
+	_ = x[OMAKECHAN-72]
+	_ = x[OMAKEMAP-73]
+	_ = x[OMAKESLICE-74]
+	_ = x[OMAKESLICECOPY-75]
+	_ = x[OMUL-76]
+	_ = x[ODIV-77]
+	_ = x[OMOD-78]
+	_ = x[OLSH-79]
+	_ = x[ORSH-80]
+	_ = x[OAND-81]
+	_ = x[OANDNOT-82]
+	_ = x[ONEW-83]
+	_ = x[ONOT-84]
+	_ = x[OBITNOT-85]
+	_ = x[OPLUS-86]
+	_ = x[ONEG-87]
+	_ = x[OOROR-88]
+	_ = x[OPANIC-89]
+	_ = x[OPRINT-90]
+	_ = x[OPRINTN-91]
+	_ = x[OPAREN-92]
+	_ = x[OSEND-93]
+	_ = x[OSLICE-94]
+	_ = x[OSLICEARR-95]
+	_ = x[OSLICESTR-96]
+	_ = x[OSLICE3-97]
+	_ = x[OSLICE3ARR-98]
+	_ = x[OSLICEHEADER-99]
+	_ = x[ORECOVER-100]
+	_ = x[ORECOVERFP-101]
+	_ = x[ORECV-102]
+	_ = x[ORUNESTR-103]
+	_ = x[OSELRECV2-104]
+	_ = x[OIOTA-105]
+	_ = x[OREAL-106]
+	_ = x[OIMAG-107]
+	_ = x[OCOMPLEX-108]
+	_ = x[OALIGNOF-109]
+	_ = x[OOFFSETOF-110]
+	_ = x[OSIZEOF-111]
+	_ = x[OUNSAFEADD-112]
+	_ = x[OUNSAFESLICE-113]
+	_ = x[OMETHEXPR-114]
+	_ = x[OMETHVALUE-115]
+	_ = x[OBLOCK-116]
+	_ = x[OBREAK-117]
+	_ = x[OCASE-118]
+	_ = x[OCONTINUE-119]
+	_ = x[ODEFER-120]
+	_ = x[OFALL-121]
+	_ = x[OFOR-122]
+	_ = x[OFORUNTIL-123]
+	_ = x[OGOTO-124]
+	_ = x[OIF-125]
+	_ = x[OLABEL-126]
+	_ = x[OGO-127]
+	_ = x[ORANGE-128]
+	_ = x[ORETURN-129]
+	_ = x[OSELECT-130]
+	_ = x[OSWITCH-131]
+	_ = x[OTYPESW-132]
+	_ = x[OFUNCINST-133]
+	_ = x[OTCHAN-134]
+	_ = x[OTMAP-135]
+	_ = x[OTSTRUCT-136]
+	_ = x[OTINTER-137]
+	_ = x[OTFUNC-138]
+	_ = x[OTARRAY-139]
+	_ = x[OTSLICE-140]
+	_ = x[OINLCALL-141]
+	_ = x[OEFACE-142]
+	_ = x[OITAB-143]
+	_ = x[OIDATA-144]
+	_ = x[OSPTR-145]
+	_ = x[OCFUNC-146]
+	_ = x[OCHECKNIL-147]
+	_ = x[OVARDEF-148]
+	_ = x[OVARKILL-149]
+	_ = x[OVARLIVE-150]
+	_ = x[ORESULT-151]
+	_ = x[OINLMARK-152]
+	_ = x[OLINKSYMOFFSET-153]
+	_ = x[OTAILCALL-154]
+	_ = x[OGETG-155]
+	_ = x[OGETCALLERPC-156]
+	_ = x[OGETCALLERSP-157]
+	_ = x[OEND-158]
 }
 
-const _Op_name = "XXXNAMENONAMETYPEPACKLITERALNILADDSUBORXORADDSTRADDRANDANDAPPENDBYTES2STRBYTES2STRTMPRUNES2STRSTR2BYTESSTR2BYTESTMPSTR2RUNESSLICE2ARRPTRASAS2AS2DOTTYPEAS2FUNCAS2MAPRAS2RECVASOPCALLCALLFUNCCALLMETHCALLINTERCAPCLOSECLOSURECOMPLITMAPLITSTRUCTLITARRAYLITSLICELITPTRLITCONVCONVIFACECONVNOPCOPYDCLDCLFUNCDCLCONSTDCLTYPEDELETEDOTDOTPTRDOTMETHDOTINTERXDOTDOTTYPEDOTTYPE2EQNELTLEGEGTDEREFINDEXINDEXMAPKEYSTRUCTKEYLENMAKEMAKECHANMAKEMAPMAKESLICEMAKESLICECOPYMULDIVMODLSHRSHANDANDNOTNEWNOTBITNOTPLUSNEGORORPANICPRINTPRINTNPARENSENDSLICESLICEARRSLICESTRSLICE3SLICE3ARRSLICEHEADERRECOVERRECOVERFPRECVRUNESTRSELRECV2IOTAREALIMAGCOMPLEXALIGNOFOFFSETOFSIZEOFUNSAFEADDUNSAFESLICEMETHEXPRMETHVALUEBLOCKBREAKCASECONTINUEDEFERFALLFORFORUNTILGOTOIFLABELGORANGERETURNSELECTSWITCHTYPESWFUNCINSTTCHANTMAPTSTRUCTTINTERTFUNCTARRAYTSLICEINLCALLEFACEITABIDATASPTRCFUNCCHECKNILVARDEFVARKILLVARLIVERESULTINLMARKLINKSYMOFFSETTAILCALLGETGGETCALLERPCGETCALLERSPEND"
+const _Op_name = "XXXNAMENONAMETYPEPACKLITERALNILADDSUBORXORADDSTRADDRANDANDAPPENDBYTES2STRBYTES2STRTMPRUNES2STRSTR2BYTESSTR2BYTESTMPSTR2RUNESSLICE2ARRPTRASAS2AS2DOTTYPEAS2FUNCAS2MAPRAS2RECVASOPCALLCALLFUNCCALLMETHCALLINTERCAPCLOSECLOSURECOMPLITMAPLITSTRUCTLITARRAYLITSLICELITPTRLITCONVCONVIFACECONVIDATACONVNOPCOPYDCLDCLFUNCDCLCONSTDCLTYPEDELETEDOTDOTPTRDOTMETHDOTINTERXDOTDOTTYPEDOTTYPE2EQNELTLEGEGTDEREFINDEXINDEXMAPKEYSTRUCTKEYLENMAKEMAKECHANMAKEMAPMAKESLICEMAKESLICECOPYMULDIVMODLSHRSHANDANDNOTNEWNOTBITNOTPLUSNEGORORPANICPRINTPRINTNPARENSENDSLICESLICEARRSLICESTRSLICE3SLICE3ARRSLICEHEADERRECOVERRECOVERFPRECVRUNESTRSELRECV2IOTAREALIMAGCOMPLEXALIGNOFOFFSETOFSIZEOFUNSAFEADDUNSAFESLICEMETHEXPRMETHVALUEBLOCKBREAKCASECONTINUEDEFERFALLFORFORUNTILGOTOIFLABELGORANGERETURNSELECTSWITCHTYPESWFUNCINSTTCHANTMAPTSTRUCTTINTERTFUNCTARRAYTSLICEINLCALLEFACEITABIDATASPTRCFUNCCHECKNILVARDEFVARKILLVARLIVERESULTINLMARKLINKSYMOFFSETTAILCALLGETGGETCALLERPCGETCALLERSPEND"
 
-var _Op_index = [...]uint16{0, 3, 7, 13, 17, 21, 28, 31, 34, 37, 39, 42, 48, 52, 58, 64, 73, 85, 94, 103, 115, 124, 136, 138, 141, 151, 158, 165, 172, 176, 180, 188, 196, 205, 208, 213, 220, 227, 233, 242, 250, 258, 264, 268, 277, 284, 288, 291, 298, 306, 313, 319, 322, 328, 335, 343, 347, 354, 362, 364, 366, 368, 370, 372, 374, 379, 384, 392, 395, 404, 407, 411, 419, 426, 435, 448, 451, 454, 457, 460, 463, 466, 472, 475, 478, 484, 488, 491, 495, 500, 505, 511, 516, 520, 525, 533, 541, 547, 556, 567, 574, 583, 587, 594, 602, 606, 610, 614, 621, 628, 636, 642, 651, 662, 670, 679, 684, 689, 693, 701, 706, 710, 713, 721, 725, 727, 732, 734, 739, 745, 751, 757, 763, 771, 776, 780, 787, 793, 798, 804, 810, 817, 822, 826, 831, 835, 840, 848, 854, 861, 868, 874, 881, 894, 902, 906, 917, 928, 931}
+var _Op_index = [...]uint16{0, 3, 7, 13, 17, 21, 28, 31, 34, 37, 39, 42, 48, 52, 58, 64, 73, 85, 94, 103, 115, 124, 136, 138, 141, 151, 158, 165, 172, 176, 180, 188, 196, 205, 208, 213, 220, 227, 233, 242, 250, 258, 264, 268, 277, 286, 293, 297, 300, 307, 315, 322, 328, 331, 337, 344, 352, 356, 363, 371, 373, 375, 377, 379, 381, 383, 388, 393, 401, 404, 413, 416, 420, 428, 435, 444, 457, 460, 463, 466, 469, 472, 475, 481, 484, 487, 493, 497, 500, 504, 509, 514, 520, 525, 529, 534, 542, 550, 556, 565, 576, 583, 592, 596, 603, 611, 615, 619, 623, 630, 637, 645, 651, 660, 671, 679, 688, 693, 698, 702, 710, 715, 719, 722, 730, 734, 736, 741, 743, 748, 754, 760, 766, 772, 780, 785, 789, 796, 802, 807, 813, 819, 826, 831, 835, 840, 844, 849, 857, 863, 870, 877, 883, 890, 903, 911, 915, 926, 937, 940}
 
 func (i Op) String() string {
 	if i >= Op(len(_Op_index)-1) {
diff --git a/src/cmd/compile/internal/noder/stencil.go b/src/cmd/compile/internal/noder/stencil.go
index 85538f590d..e308dd7a05 100644
--- a/src/cmd/compile/internal/noder/stencil.go
+++ b/src/cmd/compile/internal/noder/stencil.go
@@ -1461,24 +1461,18 @@ func (subst *subster) convertUsingDictionary(pos src.XPos, v ir.Node, gn ir.Node
 		rt = subst.getDictionaryType(pos, ix)
 	}
 
-	// Convert value to an interface type, so the data field is what we want.
-	if !v.Type().IsInterface() {
-		v = ir.NewConvExpr(v.Pos(), ir.OCONVIFACE, nil, v)
-		typed(types.NewInterface(types.LocalPkg, nil), v)
+	// Figure out what the data field of the interface will be.
+	var data ir.Node
+	if v.Type().IsInterface() {
+		data = ir.NewUnaryExpr(pos, ir.OIDATA, v)
+	} else {
+		data = ir.NewConvExpr(pos, ir.OCONVIDATA, nil, v)
 	}
-
-	// At this point, v is an interface type with a data word we want.
-	// But the type word represents a gcshape type, which we don't want.
-	// Replace with the instantiated type loaded from the dictionary.
-	data := ir.NewUnaryExpr(pos, ir.OIDATA, v)
 	typed(types.Types[types.TUNSAFEPTR], data)
+
+	// Build an interface from the type and data parts.
 	var i ir.Node = ir.NewBinaryExpr(pos, ir.OEFACE, rt, data)
 	typed(dst, i)
-	// TODO: we're throwing away the type word of the original version
-	// of m here (it would be OITAB(m)), which probably took some
-	// work to generate. Can we avoid generating it at all?
-	// (The linker will throw them away if not needed, so it would just
-	// save toolchain work, not binary size.)
 	return i
 
 }
diff --git a/src/cmd/compile/internal/reflectdata/reflect.go b/src/cmd/compile/internal/reflectdata/reflect.go
index 875d53b3cc..7eba5fb41e 100644
--- a/src/cmd/compile/internal/reflectdata/reflect.go
+++ b/src/cmd/compile/internal/reflectdata/reflect.go
@@ -1983,10 +1983,8 @@ var ZeroSize int64
 // This information is used in the linker in dead method elimination.
 func MarkTypeUsedInInterface(t *types.Type, from *obj.LSym) {
 	if t.HasShape() {
-		// TODO: shape types shouldn't be put in interfaces, so we shouldn't ever get here.
-		// We don't from ../noder/stencil.go, but we do from ../walk/walk.go when we let
-		// shape types become the types of interfaces.
-		//base.Fatalf("shape types have no methods %+v", t)
+		// Shape types shouldn't be put in interfaces, so we shouldn't ever get here.
+		base.Fatalf("shape types have no methods %+v", t)
 	}
 	tsym := TypeLinksym(t)
 	// Emit a marker relocation. The linker will know the type is converted
diff --git a/src/cmd/compile/internal/typecheck/iexport.go b/src/cmd/compile/internal/typecheck/iexport.go
index b054c73ad8..25a0bfbb3a 100644
--- a/src/cmd/compile/internal/typecheck/iexport.go
+++ b/src/cmd/compile/internal/typecheck/iexport.go
@@ -1873,7 +1873,7 @@ func (w *exportWriter) expr(n ir.Node) {
 			w.op(ir.OEND)
 		}
 
-	case ir.OCONV, ir.OCONVIFACE, ir.OCONVNOP, ir.OBYTES2STR, ir.ORUNES2STR, ir.OSTR2BYTES, ir.OSTR2RUNES, ir.ORUNESTR, ir.OSLICE2ARRPTR:
+	case ir.OCONV, ir.OCONVIFACE, ir.OCONVIDATA, ir.OCONVNOP, ir.OBYTES2STR, ir.ORUNES2STR, ir.OSTR2BYTES, ir.OSTR2RUNES, ir.ORUNESTR, ir.OSLICE2ARRPTR:
 		n := n.(*ir.ConvExpr)
 		if go117ExportTypes {
 			w.op(n.Op())
diff --git a/src/cmd/compile/internal/typecheck/iimport.go b/src/cmd/compile/internal/typecheck/iimport.go
index 9bef07b636..b389c7fcb0 100644
--- a/src/cmd/compile/internal/typecheck/iimport.go
+++ b/src/cmd/compile/internal/typecheck/iimport.go
@@ -1446,7 +1446,7 @@ func (r *importReader) node() ir.Node {
 		}
 		return n
 
-	case ir.OCONV, ir.OCONVIFACE, ir.OCONVNOP, ir.OBYTES2STR, ir.ORUNES2STR, ir.OSTR2BYTES, ir.OSTR2RUNES, ir.ORUNESTR, ir.OSLICE2ARRPTR:
+	case ir.OCONV, ir.OCONVIFACE, ir.OCONVIDATA, ir.OCONVNOP, ir.OBYTES2STR, ir.ORUNES2STR, ir.OSTR2BYTES, ir.OSTR2RUNES, ir.ORUNESTR, ir.OSLICE2ARRPTR:
 		if !go117ExportTypes && op != ir.OCONV {
 			// 	unreachable - mapped to OCONV case by exporter
 			goto error
diff --git a/src/cmd/compile/internal/walk/assign.go b/src/cmd/compile/internal/walk/assign.go
index 6d697a53ae..d4c1aafdc1 100644
--- a/src/cmd/compile/internal/walk/assign.go
+++ b/src/cmd/compile/internal/walk/assign.go
@@ -429,6 +429,7 @@ func readsMemory(n ir.Node) bool {
 		ir.OBITNOT,
 		ir.OCONV,
 		ir.OCONVIFACE,
+		ir.OCONVIDATA,
 		ir.OCONVNOP,
 		ir.ODIV,
 		ir.ODOT,
diff --git a/src/cmd/compile/internal/walk/convert.go b/src/cmd/compile/internal/walk/convert.go
index e659ee59f1..d15575f643 100644
--- a/src/cmd/compile/internal/walk/convert.go
+++ b/src/cmd/compile/internal/walk/convert.go
@@ -39,14 +39,22 @@ func walkConv(n *ir.ConvExpr, init *ir.Nodes) ir.Node {
 	return typecheck.Conv(mkcall(fn, types.Types[result], init, typecheck.Conv(n.X, types.Types[param])), n.Type())
 }
 
-// walkConvInterface walks an OCONVIFACE node.
+// walkConvInterface walks an OCONVIFACE or OCONVIDATA node.
 func walkConvInterface(n *ir.ConvExpr, init *ir.Nodes) ir.Node {
+
 	n.X = walkExpr(n.X, init)
 
 	fromType := n.X.Type()
 	toType := n.Type()
-
-	if !fromType.IsInterface() && !ir.IsBlank(ir.CurFunc.Nname) { // skip unnamed functions (func _())
+	if n.Op() == ir.OCONVIDATA {
+		// Just convert to empty interface, to make it easy.
+		// The caller throws away the type word.
+		toType = types.NewInterface(types.LocalPkg, nil)
+		// Note: don't pass fromType to MarkTypeUsedInInterface because it is likely
+		// a shape type. The appropriate call to MarkTypeUsedInInterface will come
+		// when building the dictionary (from which the matching type word will come).
+	} else if !fromType.IsInterface() && !ir.IsBlank(ir.CurFunc.Nname) {
+		// skip unnamed functions (func _())
 		reflectdata.MarkTypeUsedInInterface(fromType, ir.CurFunc.LSym)
 	}
 
diff --git a/src/cmd/compile/internal/walk/expr.go b/src/cmd/compile/internal/walk/expr.go
index eed6ef86c2..f0d37198d3 100644
--- a/src/cmd/compile/internal/walk/expr.go
+++ b/src/cmd/compile/internal/walk/expr.go
@@ -206,6 +206,13 @@ func walkExpr1(n ir.Node, init *ir.Nodes) ir.Node {
 		n := n.(*ir.ConvExpr)
 		return walkConvInterface(n, init)
 
+	case ir.OCONVIDATA:
+		n := n.(*ir.ConvExpr)
+		r := ir.NewUnaryExpr(n.Pos(), ir.OIDATA, walkConvInterface(n, init))
+		r.SetType(types.Types[types.TUNSAFEPTR])
+		r.SetTypecheck(1)
+		return r
+
 	case ir.OCONV, ir.OCONVNOP:
 		n := n.(*ir.ConvExpr)
 		return walkConv(n, init)
diff --git a/src/cmd/compile/internal/walk/order.go b/src/cmd/compile/internal/walk/order.go
index cd2bbcb73b..fe6ae3fda0 100644
--- a/src/cmd/compile/internal/walk/order.go
+++ b/src/cmd/compile/internal/walk/order.go
@@ -1156,16 +1156,20 @@ func (o *orderState) expr1(n, lhs ir.Node) ir.Node {
 
 	// concrete type (not interface) argument might need an addressable
 	// temporary to pass to the runtime conversion routine.
-	case ir.OCONVIFACE:
+	case ir.OCONVIFACE, ir.OCONVIDATA:
 		n := n.(*ir.ConvExpr)
 		n.X = o.expr(n.X, nil)
 		if n.X.Type().IsInterface() {
 			return n
 		}
-		if _, _, needsaddr := convFuncName(n.X.Type(), n.Type()); needsaddr || isStaticCompositeLiteral(n.X) {
+		to := n.Type()
+		if n.Op() == ir.OCONVIDATA {
+			to = types.NewInterface(types.LocalPkg, nil)
+		}
+		if _, _, needsaddr := convFuncName(n.X.Type(), to); needsaddr || isStaticCompositeLiteral(n.X) {
 			// Need a temp if we need to pass the address to the conversion function.
 			// We also process static composite literal node here, making a named static global
-			// whose address we can put directly in an interface (see OCONVIFACE case in walk).
+			// whose address we can put directly in an interface (see OCONVIFACE/OCONVIDATA case in walk).
 			n.X = o.addrTemp(n.X)
 		}
 		return n