spirv2nir: Rework argument handling

The argument handling of this little tool was pretty rubbish.  It had no
help and it required the filename to come first which is just strange.
This reworks it and makes things much nicer.  It's still rubbish but at
least there's a chance people can figure out how to use it now.

Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6607>

diff --git a/src/compiler/spirv/spirv2nir.c b/src/compiler/spirv/spirv2nir.c
index bbec4d2af6a699e78128c07036d4baf78e6cfb80..c6dfab0d366a1f34080ec69a2ba030786f787867 100644 (file)
--- a/src/compiler/spirv/spirv2nir.c
+++ b/src/compiler/spirv/spirv2nir.c
@@ -65,6 +65,20 @@ stage_to_enum(char *stage)
       return MESA_SHADER_NONE;
 }
 
+static void
+print_usage(char *exec_name, FILE *f)
+{
+   fprintf(f,
+"Usage: %s [options] file\n"
+"Options:\n"
+"  -h  --help              Print this help.\n"
+"  -s, --stage <stage>     Specify the shader stage.  Valid stages are:\n"
+"                          vertex, tess-ctrl, tess-eval, geometry, fragment,\n"
+"                          compute, and kernel (OpenCL-style compute).\n"
+"  -e, --entry <name>      Specify the entry-point name.\n"
+   , exec_name);
+}
+
 int main(int argc, char **argv)
 {
    gl_shader_stage shader_stage = MESA_SHADER_FRAGMENT;
@@ -73,36 +87,43 @@ int main(int argc, char **argv)
 
    static struct option long_options[] =
      {
+       {"help",         no_argument, 0, 'h'},
        {"stage",  required_argument, 0, 's'},
        {"entry",  required_argument, 0, 'e'},
        {0, 0, 0, 0}
      };
 
-   while ((ch = getopt_long(argc - 1, argv + 1, "s:e:", long_options, NULL)) != -1)
+   while ((ch = getopt_long(argc, argv, "hs:e:", long_options, NULL)) != -1)
    {
       switch (ch)
       {
-         case 's':
-            shader_stage = stage_to_enum(optarg);
-            if (shader_stage == MESA_SHADER_NONE)
-            {
-               fprintf(stderr, "Unknown stage %s\n", optarg);
-               return 1;
-            }
-            break;
-         case 'e':
-            entry_point = optarg;
-            break;
-         default:
-            fprintf(stderr, "Unrecognized option.\n");
+      case 'h':
+         print_usage(argv[0], stdout);
+         return 0;
+      case 's':
+         shader_stage = stage_to_enum(optarg);
+         if (shader_stage == MESA_SHADER_NONE)
+         {
+            fprintf(stderr, "Unknown stage \"%s\"\n", optarg);
+            print_usage(argv[0], stderr);
             return 1;
+         }
+         break;
+      case 'e':
+         entry_point = optarg;
+         break;
+      default:
+         fprintf(stderr, "Unrecognized option \"%s\".\n", optarg);
+         print_usage(argv[0], stderr);
+         return 1;
       }
    }
 
-   int fd = open(argv[1], O_RDONLY);
+   const char *filename = argv[optind];
+   int fd = open(filename, O_RDONLY);
    if (fd < 0)
    {
-      fprintf(stderr, "Failed to open %s\n", argv[1]);
+      fprintf(stderr, "Failed to open %s\n", filename);
       return 1;
    }