cmd/compile: replace opnames with stringer

Now possible, since stringer just got the -trimprefix flag added.

While at it, simplify a few Op stringifications since we can now use %v,
and no longer have to worry about o<len(opnames).

Passes toolstash -cmp on std cmd.

Fixes #15462.

Change-Id: Icdcde0b0a5eb165d18488918175024da274f782b
Reviewed-on: https://go-review.googlesource.com/76790
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Dave Cheney <dave@cheney.net>

src/cmd/compile/fmt_test.go

@@ -631,6 +631,7 @@ var knownFormats = map[string]string{
 	"cmd/compile/internal/gc.Nodes %.v":               "",
 	"cmd/compile/internal/gc.Nodes %v":                "",
 	"cmd/compile/internal/gc.Op %#v":                  "",
+	"cmd/compile/internal/gc.Op %d":                   "",
 	"cmd/compile/internal/gc.Op %v":                   "",
 	"cmd/compile/internal/gc.Val %#v":                 "",
 	"cmd/compile/internal/gc.Val %T":                  "",

src/cmd/compile/internal/gc/bexport.go

@@ -1412,7 +1412,7 @@ func (p *exporter) expr(n *Node) {
 		if op == OAPPEND {
 			p.bool(n.Isddd())
 		} else if n.Isddd() {
-			Fatalf("exporter: unexpected '...' with %s call", opnames[op])
+			Fatalf("exporter: unexpected '...' with %v call", op)
 		}
 
 	case OCALL, OCALLFUNC, OCALLMETH, OCALLINTER, OGETG:

src/cmd/compile/internal/gc/fmt.go

@@ -206,10 +206,6 @@ var goopnames = []string{
 	OXOR:      "^",
 }
 
-func (o Op) String() string {
-	return fmt.Sprint(o)
-}
-
 func (o Op) GoString() string {
 	return fmt.Sprintf("%#v", o)
 }
@@ -232,12 +228,8 @@ func (o Op) oconv(s fmt.State, flag FmtFlag, mode fmtMode) {
 		}
 	}
 
-	if int(o) < len(opnames) && opnames[o] != "" {
-		fmt.Fprint(s, opnames[o])
-		return
-	}
-
-	fmt.Fprintf(s, "O-%d", int(o))
+	// 'o.String()' instead of just 'o' to avoid infinite recursion
+	fmt.Fprint(s, o.String())
 }
 
 var classnames = []string{

src/cmd/compile/internal/gc/op_string.go

+// Code generated by "stringer -type=Op -trimprefix=O"; DO NOT EDIT.
+
+package gc
+
+import "fmt"
+
+const _Op_name = "XXXNAMENONAMETYPEPACKLITERALADDSUBORXORADDSTRADDRANDANDAPPENDARRAYBYTESTRARRAYBYTESTRTMPARRAYRUNESTRSTRARRAYBYTESTRARRAYBYTETMPSTRARRAYRUNEASAS2AS2FUNCAS2RECVAS2MAPRAS2DOTTYPEASOPCALLCALLFUNCCALLMETHCALLINTERCALLPARTCAPCLOSECLOSURECMPIFACECMPSTRCOMPLITMAPLITSTRUCTLITARRAYLITSLICELITPTRLITCONVCONVIFACECONVNOPCOPYDCLDCLFUNCDCLFIELDDCLCONSTDCLTYPEDELETEDOTDOTPTRDOTMETHDOTINTERXDOTDOTTYPEDOTTYPE2EQNELTLEGEGTINDINDEXINDEXMAPKEYSTRUCTKEYLENMAKEMAKECHANMAKEMAPMAKESLICEMULDIVMODLSHRSHANDANDNOTNEWNOTCOMPLUSMINUSORORPANICPRINTPRINTNPARENSENDSLICESLICEARRSLICESTRSLICE3SLICE3ARRRECOVERRECVRUNESTRSELRECVSELRECV2IOTAREALIMAGCOMPLEXALIGNOFOFFSETOFSIZEOFBLOCKBREAKCASEXCASECONTINUEDEFEREMPTYFALLFORFORUNTILGOTOIFLABELPROCRANGERETURNSELECTSWITCHTYPESWTCHANTMAPTSTRUCTTINTERTFUNCTARRAYDDDDDDARGINLCALLEFACEITABIDATASPTRCLOSUREVARCFUNCCHECKNILVARKILLVARLIVEINDREGSPRETJMPGETGEND"
+
+var _Op_index = [...]uint16{0, 3, 7, 13, 17, 21, 28, 31, 34, 36, 39, 45, 49, 55, 61, 73, 88, 100, 112, 127, 139, 141, 144, 151, 158, 165, 175, 179, 183, 191, 199, 208, 216, 219, 224, 231, 239, 245, 252, 258, 267, 275, 283, 289, 293, 302, 309, 313, 316, 323, 331, 339, 346, 352, 355, 361, 368, 376, 380, 387, 395, 397, 399, 401, 403, 405, 407, 410, 415, 423, 426, 435, 438, 442, 450, 457, 466, 469, 472, 475, 478, 481, 484, 490, 493, 496, 499, 503, 508, 512, 517, 522, 528, 533, 537, 542, 550, 558, 564, 573, 580, 584, 591, 598, 606, 610, 614, 618, 625, 632, 640, 646, 651, 656, 660, 665, 673, 678, 683, 687, 690, 698, 702, 704, 709, 713, 718, 724, 730, 736, 742, 747, 751, 758, 764, 769, 775, 778, 784, 791, 796, 800, 805, 809, 819, 824, 832, 839, 846, 854, 860, 864, 867}
+
+func (i Op) String() string {
+	if i >= Op(len(_Op_index)-1) {
+		return fmt.Sprintf("Op(%d)", i)
+	}
+	return _Op_name[_Op_index[i]:_Op_index[i+1]]
+}

src/cmd/compile/internal/gc/opnames.go

-// Copyright 2011 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.
-
-package gc
-
-// auto generated by go tool dist
-var opnames = []string{
-	OXXX:             "XXX",
-	ONAME:            "NAME",
-	ONONAME:          "NONAME",
-	OTYPE:            "TYPE",
-	OPACK:            "PACK",
-	OLITERAL:         "LITERAL",
-	OADD:             "ADD",
-	OSUB:             "SUB",
-	OOR:              "OR",
-	OXOR:             "XOR",
-	OADDSTR:          "ADDSTR",
-	OADDR:            "ADDR",
-	OANDAND:          "ANDAND",
-	OAPPEND:          "APPEND",
-	OARRAYBYTESTR:    "ARRAYBYTESTR",
-	OARRAYBYTESTRTMP: "ARRAYBYTESTRTMP",
-	OARRAYRUNESTR:    "ARRAYRUNESTR",
-	OSTRARRAYBYTE:    "STRARRAYBYTE",
-	OSTRARRAYBYTETMP: "STRARRAYBYTETMP",
-	OSTRARRAYRUNE:    "STRARRAYRUNE",
-	OAS:              "AS",
-	OAS2:             "AS2",
-	OAS2FUNC:         "AS2FUNC",
-	OAS2RECV:         "AS2RECV",
-	OAS2MAPR:         "AS2MAPR",
-	OAS2DOTTYPE:      "AS2DOTTYPE",
-	OASOP:            "ASOP",
-	OCALL:            "CALL",
-	OCALLFUNC:        "CALLFUNC",
-	OCALLMETH:        "CALLMETH",
-	OCALLINTER:       "CALLINTER",
-	OCALLPART:        "CALLPART",
-	OCAP:             "CAP",
-	OCLOSE:           "CLOSE",
-	OCLOSURE:         "CLOSURE",
-	OCMPIFACE:        "CMPIFACE",
-	OCMPSTR:          "CMPSTR",
-	OCOMPLIT:         "COMPLIT",
-	OMAPLIT:          "MAPLIT",
-	OSTRUCTLIT:       "STRUCTLIT",
-	OARRAYLIT:        "ARRAYLIT",
-	OSLICELIT:        "SLICELIT",
-	OPTRLIT:          "PTRLIT",
-	OCONV:            "CONV",
-	OCONVIFACE:       "CONVIFACE",
-	OCONVNOP:         "CONVNOP",
-	OCOPY:            "COPY",
-	ODCL:             "DCL",
-	ODCLFUNC:         "DCLFUNC",
-	ODCLFIELD:        "DCLFIELD",
-	ODCLCONST:        "DCLCONST",
-	ODCLTYPE:         "DCLTYPE",
-	ODELETE:          "DELETE",
-	ODOT:             "DOT",
-	ODOTPTR:          "DOTPTR",
-	ODOTMETH:         "DOTMETH",
-	ODOTINTER:        "DOTINTER",
-	OXDOT:            "XDOT",
-	ODOTTYPE:         "DOTTYPE",
-	ODOTTYPE2:        "DOTTYPE2",
-	OEQ:              "EQ",
-	ONE:              "NE",
-	OLT:              "LT",
-	OLE:              "LE",
-	OGE:              "GE",
-	OGT:              "GT",
-	OIND:             "IND",
-	OINDEX:           "INDEX",
-	OINDEXMAP:        "INDEXMAP",
-	OKEY:             "KEY",
-	OSTRUCTKEY:       "STRUCTKEY",
-	OLEN:             "LEN",
-	OMAKE:            "MAKE",
-	OMAKECHAN:        "MAKECHAN",
-	OMAKEMAP:         "MAKEMAP",
-	OMAKESLICE:       "MAKESLICE",
-	OMUL:             "MUL",
-	ODIV:             "DIV",
-	OMOD:             "MOD",
-	OLSH:             "LSH",
-	ORSH:             "RSH",
-	OAND:             "AND",
-	OANDNOT:          "ANDNOT",
-	ONEW:             "NEW",
-	ONOT:             "NOT",
-	OCOM:             "COM",
-	OPLUS:            "PLUS",
-	OMINUS:           "MINUS",
-	OOROR:            "OROR",
-	OPANIC:           "PANIC",
-	OPRINT:           "PRINT",
-	OPRINTN:          "PRINTN",
-	OPAREN:           "PAREN",
-	OSEND:            "SEND",
-	OSLICE:           "SLICE",
-	OSLICEARR:        "SLICEARR",
-	OSLICESTR:        "SLICESTR",
-	OSLICE3:          "SLICE3",
-	OSLICE3ARR:       "SLICE3ARR",
-	ORECOVER:         "RECOVER",
-	ORECV:            "RECV",
-	ORUNESTR:         "RUNESTR",
-	OSELRECV:         "SELRECV",
-	OSELRECV2:        "SELRECV2",
-	OIOTA:            "IOTA",
-	OREAL:            "REAL",
-	OIMAG:            "IMAG",
-	OCOMPLEX:         "COMPLEX",
-	OBLOCK:           "BLOCK",
-	OBREAK:           "BREAK",
-	OCASE:            "CASE",
-	OXCASE:           "XCASE",
-	OCONTINUE:        "CONTINUE",
-	ODEFER:           "DEFER",
-	OEMPTY:           "EMPTY",
-	OFALL:            "FALL",
-	OFOR:             "FOR",
-	OFORUNTIL:        "FORUNTIL",
-	OGOTO:            "GOTO",
-	OIF:              "IF",
-	OLABEL:           "LABEL",
-	OPROC:            "PROC",
-	ORANGE:           "RANGE",
-	ORETURN:          "RETURN",
-	OSELECT:          "SELECT",
-	OSWITCH:          "SWITCH",
-	OTYPESW:          "TYPESW",
-	OTCHAN:           "TCHAN",
-	OTMAP:            "TMAP",
-	OTSTRUCT:         "TSTRUCT",
-	OTINTER:          "TINTER",
-	OTFUNC:           "TFUNC",
-	OTARRAY:          "TARRAY",
-	ODDD:             "DDD",
-	ODDDARG:          "DDDARG",
-	OINLCALL:         "INLCALL",
-	OEFACE:           "EFACE",
-	OITAB:            "ITAB",
-	OIDATA:           "IDATA",
-	OSPTR:            "SPTR",
-	OCLOSUREVAR:      "CLOSUREVAR",
-	OCFUNC:           "CFUNC",
-	OCHECKNIL:        "CHECKNIL",
-	OVARKILL:         "VARKILL",
-	OVARLIVE:         "VARLIVE",
-	OINDREGSP:        "INDREGSP",
-	ORETJMP:          "RETJMP",
-	OGETG:            "GETG",
-	OEND:             "END",
-}

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

@@ -3185,7 +3185,7 @@ func (s *state) intrinsicArgs(n *Node) []*ssa.Value {
 	temps := map[*Node]*ssa.Value{}
 	for _, a := range n.List.Slice() {
 		if a.Op != OAS {
-			s.Fatalf("non-assignment as a function argument %s", opnames[a.Op])
+			s.Fatalf("non-assignment as a function argument %v", a.Op)
 		}
 		l, r := a.Left, a.Right
 		switch l.Op {
@@ -3205,7 +3205,7 @@ func (s *state) intrinsicArgs(n *Node) []*ssa.Value {
 			}
 			args = append(args, callArg{l.Xoffset, v})
 		default:
-			s.Fatalf("function argument assignment target not allowed: %s", opnames[l.Op])
+			s.Fatalf("function argument assignment target not allowed: %v", l.Op)
 		}
 	}
 	sort.Sort(byOffset(args))

src/cmd/compile/internal/gc/syntax.go

@@ -496,11 +496,13 @@ func (f *Func) setWBPos(pos src.XPos) {
 	}
 }
 
+//go:generate stringer -type=Op -trimprefix=O
+
 type Op uint8
 
 // Node ops.
 const (
-	OXXX = Op(iota)
+	OXXX Op = iota
 
 	// names
 	ONAME    // var, const or func name