cmd/compile/internal/ssa: restrict architectures for TestDebugLines_74576

CL 687815 recently added TestDebugLines_74576.

The pre-existing debug_lines_test.go file generally restricts the
tested architectures and contains multiple warnings that the
testing approach is useful but fragile, such as:

  "These files must all be short because this is super-fragile."

Despite that, initially I wanted to see what happened on the
different architectures on the trybots in case it might show something
surprising, and I let TestDebugLines_74576 run on all architectures.

That seemed to initially work, but the test is now failing on a
linux/risc64 builder (#74669), so it is likely more prudent to be
more conservative and restrict the platforms like many of the
other pre-existing tests, which is what this CL now does.

Fixes #74669

Change-Id: I9e5a7d3ee901f58253cf72e03c2239df338479e6
Reviewed-on: https://go-review.googlesource.com/c/go/+/688856
Auto-Submit: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: David Chase <drchase@google.com>

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

@@ -116,20 +116,30 @@ func TestDebugLines_53456(t *testing.T) {
 }
 
 func TestDebugLines_74576(t *testing.T) {
-	tests := []struct {
+	unixOnly(t)
-		file      string
+
-		wantStmts []int
+	switch testGoArch() {
-	}{
+	default:
-		{"i74576a.go", []int{12, 13, 13, 14}},
+		// Failed on linux/riscv64 (issue 74669), but conservatively
-		{"i74576b.go", []int{12, 13, 13, 14}},
+		// skip many architectures like several other tests here.
-		{"i74576c.go", []int{12, 13, 13, 14}},
+		t.Skip("skipped for many architectures")
-	}
+
-	t.Parallel()
+	case "arm64", "amd64", "loong64":
-	for _, test := range tests {
+		tests := []struct {
-		t.Run(test.file, func(t *testing.T) {
+			file      string
-			t.Parallel()
+			wantStmts []int
-			testDebugLines(t, "-N -l", test.file, "main", test.wantStmts, false)
+		}{
-		})
+			{"i74576a.go", []int{12, 13, 13, 14}},
+			{"i74576b.go", []int{12, 13, 13, 14}},
+			{"i74576c.go", []int{12, 13, 13, 14}},
+		}
+		t.Parallel()
+		for _, test := range tests {
+			t.Run(test.file, func(t *testing.T) {
+				t.Parallel()
+				testDebugLines(t, "-N -l", test.file, "main", test.wantStmts, false)
+			})
+		}
 	}
 }