cmd/compile/internal/ssa: fix block AuxIntType lookup

Avoid an out-of-range error when calling LongString on a generic
block.

Change-Id: I33ca88940d899bc71e3155bc63d2aa925cf83230
Reviewed-on: https://go-review.googlesource.com/c/go/+/200737
Run-TryBot: Michael Munday <mike.munday@ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>

src/cmd/compile/internal/ssa/gen/main.go

@@ -221,17 +221,19 @@ func genOp() {
 	fmt.Fprintln(w, "func (k BlockKind) String() string {return blockString[k]}")
 
 	// generate block kind auxint method
-	fmt.Fprintln(w, "var blockAuxIntType = [...]string{")
+	fmt.Fprintln(w, "func (k BlockKind) AuxIntType() string {")
+	fmt.Fprintln(w, "switch k {")
 	for _, a := range archs {
 		for _, b := range a.blocks {
 			if b.auxint == "" {
 				continue
 			}
-			fmt.Fprintf(w, "Block%s%s:\"%s\",\n", a.Name(), b.name, b.auxint)
+			fmt.Fprintf(w, "case Block%s%s: return \"%s\"\n", a.Name(), b.name, b.auxint)
 		}
 	}
 	fmt.Fprintln(w, "}")
-	fmt.Fprintln(w, "func (k BlockKind) AuxIntType() string {return blockAuxIntType[k]}")
+	fmt.Fprintln(w, "return \"\"")
+	fmt.Fprintln(w, "}")
 
 	// generate Op* declarations
 	fmt.Fprintln(w, "const (")

src/cmd/compile/internal/ssa/opGen.go

@@ -248,16 +248,20 @@ var blockString = [...]string{
 }
 
 func (k BlockKind) String() string { return blockString[k] }
-
-var blockAuxIntType = [...]string{
-	BlockS390XCIJ:   "Int8",
-	BlockS390XCGIJ:  "Int8",
-	BlockS390XCLIJ:  "UInt8",
-	BlockS390XCLGIJ: "UInt8",
+func (k BlockKind) AuxIntType() string {
+	switch k {
+	case BlockS390XCIJ:
+		return "Int8"
+	case BlockS390XCGIJ:
+		return "Int8"
+	case BlockS390XCLIJ:
+		return "UInt8"
+	case BlockS390XCLGIJ:
+		return "UInt8"
+	}
+	return ""
 }
 
-func (k BlockKind) AuxIntType() string { return blockAuxIntType[k] }
-
 const (
 	OpInvalid Op = iota