cmd/compile/internal: fix test error on loong64

For TestLogOpt test case, add loong64 support to test the host
architecture and os.

The Ctz64 is not intrinsified on loong64 for TestIntendedInlining.

Contributors to the loong64 port are:
  Weining Lu <luweining@loongson.cn>
  Lei Wang <wanglei@loongson.cn>
  Lingqin Gong <gonglingqin@loongson.cn>
  Xiaolin Zhao <zhaoxiaolin@loongson.cn>
  Meidan Li <limeidan@loongson.cn>
  Xiaojuan Zhai <zhaixiaojuan@loongson.cn>
  Qiyuan Pu <puqiyuan@loongson.cn>
  Guoqi Chen <chenguoqi@loongson.cn>

This port has been updated to Go 1.15.6:
  https://github.com/loongson/go

Updates golang#46229

Change-Id: I42280e89a337dbfde55a01a134820f8ae94f6b47
Reviewed-on: https://go-review.googlesource.com/c/go/+/400237
Reviewed-by: David Chase <drchase@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>

src/cmd/compile/internal/logopt/logopt_test.go

@@ -155,7 +155,7 @@ func s15a8(x *[15]int64) [15]int64 {
 		arches := []string{runtime.GOARCH}
 		goos0 := runtime.GOOS
 		if runtime.GOARCH == "amd64" { // Test many things with "linux" (wasm will get "js")
-			arches = []string{"arm", "arm64", "386", "amd64", "mips", "mips64", "ppc64le", "riscv64", "s390x", "wasm"}
+			arches = []string{"arm", "arm64", "386", "amd64", "mips", "mips64", "loong64", "ppc64le", "riscv64", "s390x", "wasm"}
 			goos0 = "linux"
 		}
 

src/cmd/compile/internal/test/inl_test.go

@@ -218,10 +218,10 @@ func TestIntendedInlining(t *testing.T) {
 		},
 	}
 
-	if runtime.GOARCH != "386" && runtime.GOARCH != "mips64" && runtime.GOARCH != "mips64le" && runtime.GOARCH != "riscv64" {
+	if runtime.GOARCH != "386" && runtime.GOARCH != "loong64" && runtime.GOARCH != "mips64" && runtime.GOARCH != "mips64le" && runtime.GOARCH != "riscv64" {
 		// nextFreeFast calls sys.Ctz64, which on 386 is implemented in asm and is not inlinable.
 		// We currently don't have midstack inlining so nextFreeFast is also not inlinable on 386.
-		// On mips64x and riscv64, Ctz64 is not intrinsified and causes nextFreeFast too expensive
+		// On loong64, mips64x and riscv64, Ctz64 is not intrinsified and causes nextFreeFast too expensive
 		// to inline (Issue 22239).
 		want["runtime"] = append(want["runtime"], "nextFreeFast")
 	}