[go/dev.simd] [dev.simd] simd/archsimd/_gen/cmd/refgen: generate reference implementation

[Austin Clements (Gerrit)]

Austin Clements has uploaded the change for review

Commit message

[dev.simd] simd/archsimd/_gen/cmd/refgen: generate reference implementation

This generates a reference implementation of the SIMD API backed by
the spec implementation.

Change-Id: Iaadde2d898aadf6076c06b214127d61fa26db7b8

Change diff

diff --git a/src/simd/archsimd/_gen/cmd/refgen/main.go b/src/simd/archsimd/_gen/cmd/refgen/main.go
new file mode 100644
index 0000000..af1937a
--- /dev/null
+++ b/src/simd/archsimd/_gen/cmd/refgen/main.go
@@ -0,0 +1,282 @@
+// Copyright 2026 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// refgen produces a reference implementation of the SIMD API backed by the spec
+// implementation.
+package main
+
+import (
+	"bytes"
+	"cmp"
+	"flag"
+	"fmt"
+	"go/format"
+	"go/types"
+	"io"
+	"log"
+	"maps"
+	"os"
+	"slices"
+	"strings"
+
+	"_gen/specgen"
+	"_gen/specgen/specexpr"
+)
+
+func main() {
+	flag.Usage = func() {
+		w := flag.CommandLine.Output()
+		fmt.Fprintf(w, "usage: refgen [flags] [spec dir]\n")
+		flag.CommandLine.PrintDefaults()
+	}
+
+	flag.Parse()
+	var specDir string
+	switch flag.NArg() {
+	case 0:
+		specDir = specgen.MustFindSpecDir()
+	case 1:
+		specDir = flag.Arg(0)
+	default:
+		flag.Usage()
+		os.Exit(1)
+	}
+
+	funcs, err := specgen.Load(specDir, nil)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "%s\n", err.Error())
+		os.Exit(1)
+	}
+
+	src := new(bytes.Buffer)
+
+	fmt.Fprintf(src, `// Code generated by 'refgen'. DO NOT EDIT.
+	
+package simdref
+
+import "simd/internal/spec"
+
+`)
+
+	// Define all vector types
+	vecTypeSet := make(map[specexpr.Vector]bool)
+	for _, fn := range funcs {
+		if fn.Recv.Type != nil {
+			vecTypeSet[fn.Recv.Type.(specexpr.Vector)] = true
+		}
+	}
+	vecTypes := slices.SortedFunc(maps.Keys(vecTypeSet), func(a, b specexpr.Vector) int {
+		if a.Elem != b.Elem {
+			return cmp.Compare(a.Elem.String(), b.Elem.String())
+		}
+		cmp, ok := a.Width.Compare(b.Width)
+		if ok {
+			return cmp
+		}
+		_, aScale := a.Width.(specexpr.ScalableWidth)
+		_, bScale := b.Width.(specexpr.ScalableWidth)
+		if !aScale && bScale {
+			return 1
+		}
+		return -1
+	})
+	fmt.Fprintf(src, "type (\n")
+	for _, vec := range vecTypes {
+		elem := vec.Elem.String()
+		if vec.Elem.Base == "mask" {
+			elem = fmt.Sprintf("spec.Mask%d", vec.Elem.Bits)
+		}
+
+		fmt.Fprintf(src, "\t%s struct { v []%s }\n", vec.String(), elem)
+	}
+	fmt.Fprintf(src, ")\n\n")
+
+	// Define functions
+	var args []string
+	for _, fn := range funcs {
+		sw := &srcWriter{src, 0}
+
+		fmt.Fprintf(src, "%s {\n", fn.Decl())
+
+		specName, specSig, typeArgs := fn.SpecFunc()
+		specInst, err := types.Instantiate(nil, specSig, typeArgs, false)
+		if err != nil {
+			panic(fmt.Sprintf("instantiating spec function %s: %s", specName, err))
+		}
+
+		specParams := specInst.(*types.Signature).Params()
+		args = args[:0]
+		if fn.Recv.Type != nil {
+			args = append(args, toSpec(fn.Recv.Type, specParams.At(len(args)).Type(), fn.Recv.Name, sw))
+		}
+		for _, in := range fn.In {
+			args = append(args, toSpec(in.Type, specParams.At(len(args)).Type(), in.Name, sw))
+		}
+
+		call := formatCall(specName, typeArgs, args)
+
+		specResults := specInst.(*types.Signature).Results()
+		switch len(fn.Out) {
+		case 0:
+			fmt.Fprintf(src, "\t%s\n", call)
+		case 1:
+			fmt.Fprintf(src, "\treturn %s\n", fromSpec(fn.Out[0].Type, specResults.At(0).Type(), call, sw))
+		default:
+			var tmps []string
+			var res []string
+			for i := range fn.Out {
+				tmp := fmt.Sprintf("r%d", i+1)
+				tmps = append(tmps, tmp)
+				res = append(res, fromSpec(fn.Out[i].Type, specResults.At(i).Type(), tmp, sw))
+			}
+			fmt.Fprintf(src, "\t%s := %s\n", strings.Join(tmps, ", "), call)
+			fmt.Fprintf(src, "\treturn %s\n", strings.Join(res, ", "))
+		}
+		fmt.Fprintf(src, "}\n\n")
+	}
+
+	// Emit source
+	out, err := format.Source(src.Bytes())
+	if err != nil {
+		fmt.Printf("%s", src.Bytes())
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+	fmt.Printf("%s", out)
+}
+
+func formatCall(specName string, typeArgs []types.Type, args []string) string {
+	var callBuf bytes.Buffer
+	fmt.Fprintf(&callBuf, "spec.%s[", specName)
+	for i, typeArg := range typeArgs {
+		if i > 0 {
+			callBuf.WriteString(", ")
+		}
+		types.WriteType(&callBuf, typeArg, specQualifier)
+	}
+	fmt.Fprintf(&callBuf, "](%s)", strings.Join(args, ", "))
+	return callBuf.String()
+}
+
+func specQualifier(pkg *types.Package) string {
+	if pkg.Path() == "simd/internal/spec" {
+		return "spec"
+	}
+	return ""
+}
+
+type srcWriter struct {
+	io.Writer
+	id int
+}
+
+func (w *srcWriter) genIdent() string {
+	ident := fmt.Sprintf("tmp%d", w.id)
+	w.id++
+	return ident
+}
+
+// toSpec returns an expression that converts val from the specref Go type for t
+// to spec type tt. It may write statements to src.
+func toSpec(t specexpr.Type, tt types.Type, val string, src *srcWriter) string {
+	arrayOrSlice := func(tElem specexpr.Type, ttElem types.Type) string {
+		if eVal := toSpec(tElem, ttElem, val, src); eVal == val {
+			// Easy case: the values don't need to change.
+			return val
+		}
+		// Hard case: we need to map each element
+		tmp := src.genIdent()
+		fmt.Fprintf(src, "var %s %s\n", tmp, types.TypeString(tt, specQualifier))
+		fmt.Fprintf(src, "for i := range %s {\n", val)
+		eVal := fromSpec(tElem, ttElem, "("+val+")[i]", src)
+		fmt.Fprintf(src, "\t%s[i] = %s\n", tmp, eVal)
+		fmt.Fprintf(src, "}\n")
+		return tmp
+	}
+
+	switch t := t.(type) {
+	case specexpr.Vector:
+		return val + ".v"
+	case specexpr.Basic:
+		switch tt := tt.(type) {
+		case *types.Named:
+			if tt.Obj().Name() == "UintN" {
+				return "spec.UintN(" + val + ")"
+			}
+		}
+		return val
+	case specexpr.Slice:
+		tt := tt.Underlying().(*types.Slice)
+		return arrayOrSlice(t.Elem, tt.Elem())
+	case specexpr.Array:
+		switch tt := tt.(type) {
+		case *types.Named:
+			if tt.Obj().Name() == "Array" {
+				return toSpec(t.Elem, tt.TypeArgs().At(0), val, src) + "[:]"
+			}
+		}
+		tt := tt.Underlying().(*types.Array)
+		return arrayOrSlice(t.Elem, tt.Elem())
+	case specexpr.Pointer:
+		tt := tt.(*types.Pointer)
+		eVal := toSpec(t.Elem, tt.Elem(), val, src)
+		tmp := src.genIdent()
+		fmt.Fprintf(src, "var %s %s = %s\n", tmp, types.TypeString(tt.Elem(), specQualifier), eVal)
+		return "&" + tmp
+	}
+	log.Fatalf("unexpected specexpr type %s (%T)", t, t)
+	panic("not reachable")
+}
+
+// fromSpec returns an expression that converts val from the spec package type
+// tt to the specref Go type for t. It may write statements to src.
+func fromSpec(t specexpr.Type, tt types.Type, val string, src *srcWriter) string {
+	arrayOrSlice := func(tElem specexpr.Type, ttElem types.Type) string {
+		if eVal := fromSpec(tElem, ttElem, val, src); eVal == val {
+			// Easy case: the values don't need to change.
+			return val
+		}
+		// Hard case: we need to map each element
+		tmp := src.genIdent()
+		fmt.Fprintf(src, "var %s %s\n", tmp, t)
+		fmt.Fprintf(src, "for i := range %s {\n", val)
+		eVal := fromSpec(tElem, ttElem, "("+val+")[i]", src)
+		fmt.Fprintf(src, "\t%s[i] = %s\n", tmp, eVal)
+		fmt.Fprintf(src, "}\n")
+		return tmp
+	}
+
+	switch t := t.(type) {
+	case specexpr.Vector:
+		return fmt.Sprintf("%s{%s}", t, val)
+	case specexpr.Basic:
+		switch tt := tt.(type) {
+		case *types.Named:
+			if tt.Obj().Name() == "UintN" {
+				return fmt.Sprintf("%s(%s)", t, val)
+			}
+		}
+		return val
+	case specexpr.Slice:
+		tt := tt.Underlying().(*types.Slice)
+		return arrayOrSlice(t.Elem, tt.Elem())
+	case specexpr.Array:
+		switch tt := tt.(type) {
+		case *types.Named:
+			if tt.Obj().Name() == "Array" {
+				return fmt.Sprintf("(%s)(%s)", t, fromSpec(t.Elem, tt.TypeArgs().At(0), val, src))
+			}
+		}
+		tt := tt.Underlying().(*types.Array)
+		return arrayOrSlice(t.Elem, tt.Elem())
+	case specexpr.Pointer:
+		tt := tt.(*types.Pointer)
+		eVal := fromSpec(t.Elem, tt.Elem(), val, src)
+		tmp := src.genIdent()
+		fmt.Fprintf(src, "var %s %s = %s\n", tmp, t, eVal)
+		return "&" + tmp
+	}
+	log.Fatalf("unexpected specexpr type %s (%T)", t, t)
+	panic("not reachable")
+}
diff --git a/src/simd/archsimd/_gen/specgen/api.go b/src/simd/archsimd/_gen/specgen/api.go
index f7788c7..87391f0 100644
--- a/src/simd/archsimd/_gen/specgen/api.go
+++ b/src/simd/archsimd/_gen/specgen/api.go
@@ -7,6 +7,7 @@
 import (
 	"_gen/specgen/specexpr"
 	"fmt"
+	"go/types"
 	"strings"
 )
 
@@ -23,6 +24,12 @@
 
 	In  []Arg
 	Out []Arg
+
+	// specFunc and instance describe the underlying spec function and its
+	// instantiation that led to this API function.
+	specFunc      *specFunc
+	typeParamVars map[*types.TypeParam]specexpr.Variable
+	instance      *specexpr.Bindings
 }
 
 type Arg struct {
@@ -76,3 +83,30 @@
 	buf.WriteString(f.Signature())
 	return buf.String()
 }
+
+// SpecFunc returns information about the spec package function that generated
+// f. name is the name of the function in the spec package, sig is its
+// uninstantiated signature type, and typeArgs is a slice of the type arguments
+// it was instantiated on to construct f.
+func (f *Func) SpecFunc() (name string, sig *types.Signature, typeArgs []types.Type) {
+	sFn := f.specFunc
+
+	// Build instantiated signature
+	for _, tparam := range sFn.TypeParams {
+		val := f.instance.Get(f.typeParamVars[tparam])
+		switch val := val.(type) {
+		case specexpr.Type:
+			typeArgs = append(typeArgs, specTypeToType(sFn.Pkg, val))
+		case specexpr.Num:
+			wt := sFn.Pkg.WidthTypes[val]
+			if wt == nil {
+				panic(fmt.Sprintf("no spec package type for width %s", val))
+			}
+			typeArgs = append(typeArgs, wt)
+		default:
+			panic("unexpected type parameter value")
+		}
+	}
+
+	return sFn.Name, sFn.Sig, typeArgs
+}
diff --git a/src/simd/archsimd/_gen/specgen/expand.go b/src/simd/archsimd/_gen/specgen/expand.go
index 3be9fb7..f2935e0 100644
--- a/src/simd/archsimd/_gen/specgen/expand.go
+++ b/src/simd/archsimd/_gen/specgen/expand.go
@@ -75,6 +75,7 @@
 		if fn == nil {
 			continue
 		}
+		fn.typeParamVars = typeParamVars
 
 		funcs = append(funcs, fn)
 	}
@@ -89,6 +90,9 @@
 func (sFn *specFunc) instantiate(ctx context, b *specexpr.Bindings, argGet map[*types.Var]func(*specexpr.Bindings) specexpr.Type) *Func {
 	var f Func
 
+	f.specFunc = sFn
+	f.instance = b
+
 	// Function or method?
 	var method bool
 	if len(sFn.Params) > 0 {
diff --git a/src/simd/archsimd/_gen/specgen/loadspec.go b/src/simd/archsimd/_gen/specgen/loadspec.go
index 72ed1f7..e0aba3a 100644
--- a/src/simd/archsimd/_gen/specgen/loadspec.go
+++ b/src/simd/archsimd/_gen/specgen/loadspec.go
@@ -26,6 +26,9 @@
 	TypeElems  map[types.Type]specexpr.Basic
 	TypeWidths map[types.Type]specexpr.Num
 
+	ElemTypes  map[specexpr.Basic]types.Type
+	WidthTypes map[specexpr.Num]types.Type
+
 	VecType   types.Type // Uninstantiated Vec type
 	ArrayType types.Type // Uninstantiated Array type
 	UintNType types.Type // Uninstantiated UintN type
@@ -187,17 +190,21 @@
 
 	// Gather types corresponding to shape constraints
 	typeElems := make(map[types.Type]specexpr.Basic)
+	elemTypes := make(map[specexpr.Basic]types.Type)
 	if eltOrMask := lookupType("EltOrMask"); eltOrMask != nil {
 		for _, elt := range typeSet(eltOrMask) {
 			basic := shapeElemType(elt)
 			typeElems[elt] = basic
+			elemTypes[basic] = elt
 		}
 	}
 	typeWidths := make(map[types.Type]specexpr.Num)
+	widthTypes := make(map[specexpr.Num]types.Type)
 	if width := lookupType("Width"); width != nil {
 		for _, width := range typeSet(width) {
 			val := shapeWidthVal(width)
 			typeWidths[width] = val
+			widthTypes[val] = width
 		}
 	}
 
@@ -213,6 +220,8 @@
 		Funcs:      funcs,
 		TypeElems:  typeElems,
 		TypeWidths: typeWidths,
+		ElemTypes:  elemTypes,
+		WidthTypes: widthTypes,
 		VecType:    vecType,
 		ArrayType:  arrayType,
 		UintNType:  uintNType,
diff --git a/src/simd/archsimd/_gen/specgen/types.go b/src/simd/archsimd/_gen/specgen/types.go
index 6cf7ed3..8c02ebc 100644
--- a/src/simd/archsimd/_gen/specgen/types.go
+++ b/src/simd/archsimd/_gen/specgen/types.go
@@ -163,6 +163,41 @@
 	panic(fmt.Sprintf("parsing width type %s: %s", t, err))
 }
 
+var basicToBasic = map[specexpr.Basic]types.BasicKind{
+	{Base: "int", Bits: 0}:    types.Int,
+	{Base: "int", Bits: 8}:    types.Int8,
+	{Base: "int", Bits: 16}:   types.Int16,
+	{Base: "int", Bits: 32}:   types.Int32,
+	{Base: "int", Bits: 64}:   types.Int64,
+	{Base: "uint", Bits: 0}:   types.Uint,
+	{Base: "uint", Bits: 8}:   types.Uint8,
+	{Base: "uint", Bits: 16}:  types.Uint16,
+	{Base: "uint", Bits: 32}:  types.Uint32,
+	{Base: "uint", Bits: 64}:  types.Uint64,
+	{Base: "float", Bits: 32}: types.Float32,
+	{Base: "float", Bits: 64}: types.Float64,
+}
+
+func specTypeToType(pkg *specPackage, t specexpr.Type) types.Type {
+	switch t := t.(type) {
+	case specexpr.Basic:
+		var t2 types.Type
+		if t.Base == "Mask" {
+			t2 = pkg.ElemTypes[t]
+		} else {
+			if kind, ok := basicToBasic[t]; ok {
+				t2 = types.Typ[kind]
+			}
+		}
+		if t2 == nil {
+			panic(fmt.Sprintf("unknown basic type %s", t))
+		}
+		return t2
+	}
+	// TODO: Implement other specexpr.Type types if we need them
+	panic(fmt.Sprintf("unimplemented specTypeToType for %T", t))
+}
+
 type argBinder struct {
 	ctx        context
 	pkg        *specPackage

Change information

Files:

• A src/simd/archsimd/_gen/cmd/refgen/main.go
• M src/simd/archsimd/_gen/specgen/api.go
• M src/simd/archsimd/_gen/specgen/expand.go
• M src/simd/archsimd/_gen/specgen/loadspec.go
• M src/simd/archsimd/_gen/specgen/types.go

Change size: L

Delta: 5 files changed, 364 insertions(+), 0 deletions(-)

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File src/simd/archsimd/_gen/cmd/refgen/main.go

Line 55, Patchset 2 (Latest):

David Chase . unresolved

technically an unwanted whitespace, but that will be fixed by formatted output.

Line 151, Patchset 2 (Latest): // This may be used as a defer. On panic, flush what we have an repanic.

David Chase . unresolved

"and"

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File src/simd/archsimd/_gen/cmd/refgen/main.go

Line 55, Patchset 2:

David Chase . resolved

technically an unwanted whitespace, but that will be fixed by formatted output.

Austin Clements

Done

Line 151, Patchset 2: // This may be used as a defer. On panic, flush what we have an repanic.

David Chase . resolved

"and"

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[Austin Clements (Gerrit)]

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Austin Clements uploaded new patchset

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Austin Clements would like David Chase and Junyang Shao to review this change.

Commit message

simd/archsimd/_gen/cmd/refgen: generate reference implementation

This generates a reference implementation of the SIMD API backed by
the spec implementation.

Change-Id: Iaadde2d898aadf6076c06b214127d61fa26db7b8

Change diff

diff --git a/src/simd/archsimd/_gen/cmd/refgen/main.go b/src/simd/archsimd/_gen/cmd/refgen/main.go
new file mode 100644

index 0000000..6db306a
--- /dev/null
+++ b/src/simd/archsimd/_gen/cmd/refgen/main.go
@@ -0,0 +1,289 @@

+// Copyright 2026 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// refgen produces a reference implementation of the SIMD API backed by the spec
+// implementation.
+package main
+
+import (
+	"bytes"
+	"cmp"
+	"flag"
+	"fmt"
+	"go/format"
+	"go/types"

+	"log"
+	"maps"
+	"os"
+	"slices"
+	"strings"
+

+	"simd/archsimd/_gen/specgen"
+	"simd/archsimd/_gen/specgen/specexpr"

+	src := new(srcWriter)
+	defer src.flushOrDie()

+		if vec.Elem.Base == "Mask" {

+			elem = fmt.Sprintf("spec.Mask%d", vec.Elem.Bits)
+		}
+
+		fmt.Fprintf(src, "\t%s struct { v []%s }\n", vec.String(), elem)
+	}
+	fmt.Fprintf(src, ")\n\n")
+
+	// Define functions
+	var args []string
+	for _, fn := range funcs {

+		fmt.Fprintf(src, "%s {\n", fn.Decl())

+		src.id = 0

+
+		specName, specSig, typeArgs := fn.SpecFunc()
+		specInst, err := types.Instantiate(nil, specSig, typeArgs, false)
+		if err != nil {
+			panic(fmt.Sprintf("instantiating spec function %s: %s", specName, err))
+		}
+
+		specParams := specInst.(*types.Signature).Params()
+		args = args[:0]
+		if fn.Recv.Type != nil {

+			args = append(args, toSpec(fn.Recv.Type, specParams.At(len(args)).Type(), fn.Recv.Name, src))

+		}
+		for _, in := range fn.In {

+			args = append(args, toSpec(in.Type, specParams.At(len(args)).Type(), in.Name, src))

+		}
+
+		call := formatCall(specName, typeArgs, args)
+
+		specResults := specInst.(*types.Signature).Results()
+		switch len(fn.Out) {
+		case 0:
+			fmt.Fprintf(src, "\t%s\n", call)
+		case 1:

+			fmt.Fprintf(src, "\treturn %s\n", fromSpec(fn.Out[0].Type, specResults.At(0).Type(), call, src))

+		default:
+			var tmps []string
+			var res []string
+			for i := range fn.Out {
+				tmp := fmt.Sprintf("r%d", i+1)
+				tmps = append(tmps, tmp)

+				res = append(res, fromSpec(fn.Out[i].Type, specResults.At(i).Type(), tmp, src))

+			}
+			fmt.Fprintf(src, "\t%s := %s\n", strings.Join(tmps, ", "), call)
+			fmt.Fprintf(src, "\treturn %s\n", strings.Join(res, ", "))
+		}
+		fmt.Fprintf(src, "}\n\n")
+	}
+}
+

+type srcWriter struct {
+	bytes.Buffer

+	id int
+}
+
+func (w *srcWriter) genIdent() string {
+	ident := fmt.Sprintf("tmp%d", w.id)
+	w.id++
+	return ident
+}
+

+func (w *srcWriter) flushOrDie() {
+	// This may be used as a defer. On panic, flush what we have and repanic.
+	if p := recover(); p != nil {
+		os.Stdout.Write(w.Bytes())
+		panic(p)
+	}
+
+	out, err := format.Source(w.Bytes())

+	if err != nil {

+		os.Stdout.Write(w.Bytes())

+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}

+	os.Stdout.Write(out)
+	w.Reset()

+}
+
+func formatCall(specName string, typeArgs []types.Type, args []string) string {
+	var callBuf bytes.Buffer
+	fmt.Fprintf(&callBuf, "spec.%s[", specName)
+	for i, typeArg := range typeArgs {
+		if i > 0 {
+			callBuf.WriteString(", ")
+		}
+		types.WriteType(&callBuf, typeArg, specQualifier)
+	}
+	fmt.Fprintf(&callBuf, "](%s)", strings.Join(args, ", "))
+	return callBuf.String()
+}
+
+func specQualifier(pkg *types.Package) string {
+	if pkg.Path() == "simd/internal/spec" {
+		return "spec"
+	}
+	return ""
+}
+

index 0a2c0cc..f55c5cf 100644
--- a/src/simd/archsimd/_gen/specgen/api.go
+++ b/src/simd/archsimd/_gen/specgen/api.go
@@ -6,6 +6,7 @@
 
 import (
 	"fmt"
+	"go/types"
 	"simd/archsimd/_gen/specgen/specexpr"

index 06e3376..6f6f195 100644

--- a/src/simd/archsimd/_gen/specgen/expand.go
+++ b/src/simd/archsimd/_gen/specgen/expand.go
@@ -75,6 +75,7 @@
 		if fn == nil {
 			continue
 		}
+		fn.typeParamVars = typeParamVars
 
 		funcs = append(funcs, fn)
 	}
@@ -89,6 +90,9 @@
 func (sFn *specFunc) instantiate(ctx context, b *specexpr.Bindings, argGet map[*types.Var]func(*specexpr.Bindings) specexpr.Type) *Func {
 	var f Func
 
+	f.specFunc = sFn
+	f.instance = b
+
 	// Function or method?
 	var method bool
 	if len(sFn.Params) > 0 {
diff --git a/src/simd/archsimd/_gen/specgen/loadspec.go b/src/simd/archsimd/_gen/specgen/loadspec.go

index 4b96e30..84e9f6c 100644
--- a/src/simd/archsimd/_gen/specgen/loadspec.go
+++ b/src/simd/archsimd/_gen/specgen/loadspec.go
@@ -25,6 +25,9 @@

 	TypeElems  map[types.Type]specexpr.Basic
 	TypeWidths map[types.Type]specexpr.Num
 
+	ElemTypes  map[specexpr.Basic]types.Type
+	WidthTypes map[specexpr.Num]types.Type
+
 	VecType   types.Type // Uninstantiated Vec type
 	ArrayType types.Type // Uninstantiated Array type
 	UintNType types.Type // Uninstantiated UintN type

@@ -186,17 +189,21 @@

 
 	// Gather types corresponding to shape constraints
 	typeElems := make(map[types.Type]specexpr.Basic)
+	elemTypes := make(map[specexpr.Basic]types.Type)
 	if eltOrMask := lookupType("EltOrMask"); eltOrMask != nil {
 		for _, elt := range typeSet(eltOrMask) {
 			basic := shapeElemType(elt)
 			typeElems[elt] = basic
+			elemTypes[basic] = elt
 		}
 	}
 	typeWidths := make(map[types.Type]specexpr.Num)
+	widthTypes := make(map[specexpr.Num]types.Type)
 	if width := lookupType("Width"); width != nil {
 		for _, width := range typeSet(width) {
 			val := shapeWidthVal(width)
 			typeWidths[width] = val
+			widthTypes[val] = width
 		}
 	}
 

@@ -212,6 +219,8 @@

 		Funcs:      funcs,
 		TypeElems:  typeElems,
 		TypeWidths: typeWidths,
+		ElemTypes:  elemTypes,
+		WidthTypes: widthTypes,
 		VecType:    vecType,
 		ArrayType:  arrayType,
 		UintNType:  uintNType,
diff --git a/src/simd/archsimd/_gen/specgen/types.go b/src/simd/archsimd/_gen/specgen/types.go

index 07b0a7b..4c1551c 100644
--- a/src/simd/archsimd/_gen/specgen/types.go
+++ b/src/simd/archsimd/_gen/specgen/types.go
@@ -162,6 +162,41 @@

diff --git a/src/simd/internal/spec/TASKS.md b/src/simd/internal/spec/TASKS.md
index 37c3fb7..532f061 100644
--- a/src/simd/internal/spec/TASKS.md
+++ b/src/simd/internal/spec/TASKS.md
@@ -25,7 +25,7 @@
   Maybe the hand-written code still lives directly in archsimd, but as
   unexported function, and the generator writes the trivial exported API glue
   for these.
-- [ ] Generate a full reference implementation for testing that provides the
-  SIMD API but just wraps the spec package.
+- [x] Generate a full reference implementation for testing that provides the
+  SIMD API but just wraps the spec package. (Done: _gen/cmd/refgen)
 - [ ] Generate conformance tests of the archsimd API against the spec testing
   layer.

Change information

Files:

• A src/simd/archsimd/_gen/cmd/refgen/main.go
• M src/simd/archsimd/_gen/specgen/api.go
• M src/simd/archsimd/_gen/specgen/expand.go
• M src/simd/archsimd/_gen/specgen/loadspec.go
• M src/simd/archsimd/_gen/specgen/types.go

• M src/simd/internal/spec/TASKS.md

Change size: L

Delta: 6 files changed, 373 insertions(+), 2 deletions(-)

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• David Chase
• Junyang Shao

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Gerrit

Gerrit-MessageType: newchange

Gerrit-Project: go

Gerrit-Branch: master

Gerrit-Change-Id: Iaadde2d898aadf6076c06b214127d61fa26db7b8

Gerrit-Change-Number: 812064

Gerrit-PatchSet: 1

Gerrit-Owner: Austin Clements <aus...@google.com>

Gerrit-Reviewer: Austin Clements <aus...@google.com>

Gerrit-Reviewer: David Chase <drc...@google.com>

Gerrit-Reviewer: Junyang Shao <shaoj...@google.com>

Gerrit-CC: Cherry Mui <cher...@google.com>

Gerrit-Attention: David Chase <drc...@google.com>

Gerrit-Attention: Junyang Shao <shaoj...@google.com>