cmd/internal/obj/loong64: simplify buildop

The length of array optab is readily available, remove the sentinel and
sentinel scan, like arm64.

Change-Id: Iceeed22587ce2beeedeb5babdde3474e75d70f89
Reviewed-on: https://go-review.googlesource.com/c/go/+/699095
Reviewed-by: abner chenc <chenguoqi@loongson.cn>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Meidan Li <limeidan@loongson.cn>

diff --git a/src/cmd/internal/obj/loong64/asm.go b/src/cmd/internal/obj/loong64/asm.go
index ffd1177350b119af23db790a26a20831961f6bf3..5d85585ebec11ed6024ca3b3b376a29f5fe3307e 100644 (file)
--- a/src/cmd/internal/obj/loong64/asm.go
+++ b/src/cmd/internal/obj/loong64/asm.go
@@ -438,8 +438,6 @@ var optab = []Optab{
        {obj.ANOP, C_FREG, C_NONE, C_NONE, C_NONE, C_NONE, 0, 0, 0, 0},
        {obj.ADUFFZERO, C_NONE, C_NONE, C_NONE, C_BRAN, C_NONE, 11, 4, 0, 0}, // same as AJMP
        {obj.ADUFFCOPY, C_NONE, C_NONE, C_NONE, C_BRAN, C_NONE, 11, 4, 0, 0}, // same as AJMP
-
-       {obj.AXXX, C_NONE, C_NONE, C_NONE, C_NONE, C_NONE, 0, 4, 0, 0},
 }
 
 var atomicInst = map[obj.As]uint32{
@@ -1303,31 +1301,27 @@ func buildop(ctxt *obj.Link) {
                return
        }
 
-       var n int
-
-       for i := 0; i < C_NCLASS; i++ {
-               for n = 0; n < C_NCLASS; n++ {
-                       if cmp(n, i) {
-                               xcmp[i][n] = true
+       for i := range C_NCLASS {
+               for j := range C_NCLASS {
+                       if cmp(j, i) {
+                               xcmp[i][j] = true
                        }
                }
        }
-       for n = 0; optab[n].as != obj.AXXX; n++ {
-       }
-       slices.SortFunc(optab[:n], ocmp)
-       for i := 0; i < n; i++ {
-               r := optab[i].as
-               r0 := r & obj.AMask
-               start := i
-               for optab[i].as == r {
-                       i++
-               }
-               oprange[r0] = optab[start:i]
-               i--
 
-               switch r {
+       slices.SortFunc(optab, ocmp)
+       for i := 0; i < len(optab); i++ {
+               as, start := optab[i].as, i
+               for ; i < len(optab)-1; i++ {
+                       if optab[i+1].as != as {
+                               break
+                       }
+               }
+               r0 := as & obj.AMask
+               oprange[r0] = optab[start : i+1]
+               switch as {
                default:
-                       ctxt.Diag("unknown op in build: %v", r)
+                       ctxt.Diag("unknown op in build: %v", as)
                        ctxt.DiagFlush()
                        log.Fatalf("bad code")