Fix bugs in cli

src/compiler/NubLang.CLI/QBE.cs

@@ -4,13 +4,12 @@ namespace NubLang.CLI;
 
 public static class QBE
 {
-    public static async Task<string?> Invoke(string ssa)
+    public static async Task<bool> Invoke(string ssaPath, string outPath)
     {
         using var process = new Process();
-        process.StartInfo = new ProcessStartInfo("qbe")
+        process.StartInfo = new ProcessStartInfo("qbe", ["-o", outPath, ssaPath])
         {
             UseShellExecute = false,
-            RedirectStandardInput = true,
             RedirectStandardOutput = true,
             RedirectStandardError = true,
             CreateNoWindow = true
@@ -18,9 +17,6 @@ public static class QBE
 
         process.Start();
 
-        await process.StandardInput.WriteAsync(ssa);
-        process.StandardInput.Close();
-
         await process.WaitForExitAsync();
 
         var errors = await process.StandardError.ReadToEndAsync();
@@ -29,8 +25,6 @@ public static class QBE
             await Console.Error.WriteLineAsync("qbe error:\n" + errors);
         }
 
-        var asm = await process.StandardOutput.ReadToEndAsync();
-
-        return process.ExitCode == 0 ? asm : null;
+        return process.ExitCode == 0;
     }
-}
+}