cmd/compile: use stringer on types.EType

Another one that is possible thanks to the new -trimprefix stringer
flag.

The only subtle difference is that, in the previous version, some values
such as TUNSAFEPTR were stringified as "TUNSAFEPTR" instead of
"UNSAFEPTR". The new String method is always consistent in removing the
"T" prefix.

Passes toolstash -cmp on std cmd.

Change-Id: I68407f391795403dfcbbfa68c813018c0235bbb5
Reviewed-on: https://go-review.googlesource.com/77250
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Marvin Stenger <marvin.stenger94@gmail.com>
Reviewed-by: Robert Griesemer <gri@golang.org>

src/cmd/compile/internal/types/etype_string.go

+// Code generated by "stringer -type EType -trimprefix T"; DO NOT EDIT.
+
+package types
+
+import "fmt"
+
+const _EType_name = "xxxINT8UINT8INT16UINT16INT32UINT32INT64UINT64INTUINTUINTPTRCOMPLEX64COMPLEX128FLOAT32FLOAT64BOOLPTR32PTR64FUNCSLICEARRAYSTRUCTCHANMAPINTERFORWANYSTRINGUNSAFEPTRIDEALNILBLANKFUNCARGSCHANARGSDDDFIELDSSATUPLENTYPE"
+
+var _EType_index = [...]uint8{0, 3, 7, 12, 17, 23, 28, 34, 39, 45, 48, 52, 59, 68, 78, 85, 92, 96, 101, 106, 110, 115, 120, 126, 130, 133, 138, 142, 145, 151, 160, 165, 168, 173, 181, 189, 197, 200, 205, 210}
+
+func (i EType) String() string {
+	if i >= EType(len(_EType_index)-1) {
+		return fmt.Sprintf("EType(%d)", i)
+	}
+	return _EType_name[_EType_index[i]:_EType_index[i+1]]
+}

src/cmd/compile/internal/types/type.go

@@ -15,11 +15,13 @@ import (
 // TODO(gri) try to eliminate soon
 type Node struct{ _ int }
 
+//go:generate stringer -type EType -trimprefix T
+
 // EType describes a kind of type.
 type EType uint8
 
 const (
-	Txxx = iota
+	Txxx EType = iota
 
 	TINT8
 	TUINT8

src/cmd/compile/internal/types/utils.go

@@ -76,51 +76,3 @@ func (f *bitset8) set(mask uint8, b bool) {
 		*(*uint8)(f) &^= mask
 	}
 }
-
-var etnames = []string{
-	Txxx:        "Txxx",
-	TINT:        "INT",
-	TUINT:       "UINT",
-	TINT8:       "INT8",
-	TUINT8:      "UINT8",
-	TINT16:      "INT16",
-	TUINT16:     "UINT16",
-	TINT32:      "INT32",
-	TUINT32:     "UINT32",
-	TINT64:      "INT64",
-	TUINT64:     "UINT64",
-	TUINTPTR:    "UINTPTR",
-	TFLOAT32:    "FLOAT32",
-	TFLOAT64:    "FLOAT64",
-	TCOMPLEX64:  "COMPLEX64",
-	TCOMPLEX128: "COMPLEX128",
-	TBOOL:       "BOOL",
-	TPTR32:      "PTR32",
-	TPTR64:      "PTR64",
-	TFUNC:       "FUNC",
-	TARRAY:      "ARRAY",
-	TSLICE:      "SLICE",
-	TSTRUCT:     "STRUCT",
-	TCHAN:       "CHAN",
-	TMAP:        "MAP",
-	TINTER:      "INTER",
-	TFORW:       "FORW",
-	TSTRING:     "STRING",
-	TUNSAFEPTR:  "TUNSAFEPTR",
-	TANY:        "ANY",
-	TIDEAL:      "TIDEAL",
-	TNIL:        "TNIL",
-	TBLANK:      "TBLANK",
-	TFUNCARGS:   "TFUNCARGS",
-	TCHANARGS:   "TCHANARGS",
-	TDDDFIELD:   "TDDDFIELD",
-	TSSA:        "TSSA",
-	TTUPLE:      "TTUPLE",
-}
-
-func (et EType) String() string {
-	if int(et) < len(etnames) && etnames[et] != "" {
-		return etnames[et]
-	}
-	return fmt.Sprintf("E-%d", et)
-}