internal/ximdgen: drop $xi/$xf shorthands

These were string shorthands for x86 integer and float suffixes,
respectively, but in practice they were easy to confuse with
unification variables (also $<varname>) and just required knowing more
stuff in order to understand the unification rules.

Drop them and just spell it out.

Change-Id: I38a0446e428a92c9e89be4e90d1beff16e48e714
Reviewed-on: https://go-review.googlesource.com/c/arch/+/674177
Auto-Submit: Austin Clements <[email protected]>
Reviewed-by: David Chase <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>

Author: aclements

internal/simdgen/go.yaml

@@ -2,7 +2,7 @@
 # For binary operations, we constrain their two inputs and one output to the
 # same Go type using a variable.
 - go: Add
-  asm: "V?PADD$xi|V?ADDP$xf"
+  asm: "V?PADD[BWDQ]|V?ADDP[SD]"
   in:
   - go: $t
   - go: $t
@@ -11,7 +11,7 @@
 
 - go: Sub
   goarch: amd64
-  asm: "V?PSUB$xi|V?SUBP$xf"
+  asm: "V?PSUB[BWDQ]|V?SUBP[SD]"
   in:
   - go: $t
   - go: $t

internal/simdgen/main.go

@@ -72,11 +72,6 @@ var (
 	flagDebugHTML  = flag.String("debug-html", "", "write unification trace to `file.html`")
 )
 
-var yamlSubs = strings.NewReplacer(
-	"$xi", "[BWDQ]", // x86 integer suffixes
-	"$xf", "[SD]", // x86 float suffixes
-)
-
 func main() {
 	flag.Parse()
 
@@ -92,7 +87,7 @@ func main() {
 	if *flagQ != "" {
 		r := strings.NewReader(*flagQ)
 		var def unify.Closure
-		if err := def.Unmarshal(r, unify.UnmarshalOpts{Path: "<query>", StringReplacer: yamlSubs.Replace}); err != nil {
+		if err := def.Unmarshal(r, unify.UnmarshalOpts{Path: "<query>"}); err != nil {
 			log.Fatalf("parsing -q: %s", err)
 		}
 		inputs = append(inputs, def)
@@ -171,7 +166,7 @@ func loadValue(path string) (unify.Closure, error) {
 	defer f.Close()
 
 	var c unify.Closure
-	if err := c.Unmarshal(f, unify.UnmarshalOpts{StringReplacer: yamlSubs.Replace}); err != nil {
+	if err := c.Unmarshal(f, unify.UnmarshalOpts{}); err != nil {
 		return unify.Closure{}, fmt.Errorf("%s: %v", path, err)
 	}
 	return c, nil