add support for printing help for pragmas (#1905)

add support for printing help for pragmas Printing help is a backend specific option. It requires a bit more flexible parsing of annotations (i.e., registering handlers outside the constructor) and a bit of driver tweaking.
p4lang · Apr 27, 2019 · d8a04d0 · d8a04d0
1 parent 6b230f4
commit d8a04d0
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Showing 2 changed files with 26 additions and 5 deletions.
diff --git a/frontends/p4/parseAnnotations.h b/frontends/p4/parseAnnotations.h
@@ -123,6 +123,8 @@ class ParseAnnotations : public Modifier {
     static bool parseExpressionList(IR::Annotation* annotation);
     static bool parseKvList(IR::Annotation* annotation);
 
+    void addHandler(cstring name, Handler h) { handlers.insert({name, h}); }
+
  private:
     /// Whether to warn about unknown annotations.
     const bool warnUnknown;

diff --git a/tools/driver/p4c_src/main.py b/tools/driver/p4c_src/main.py
@@ -116,7 +116,7 @@ def main():
     parser.add_argument("-I", dest="search_path",
                         help="Add directory to include search path",
                         action="append", default=[])
-    parser.add_argument("-o", dest="output_directory",
+    parser.add_argument("-o", "--output", dest="output_directory",
                         help="Write output to the provided path",
                         action="store", metavar="PATH", default=".")
     parser.add_argument("--p4runtime-file",
@@ -136,14 +136,19 @@ def main():
                         "description (default is binary). "
                         "[Deprecated; use '--p4runtime-files' instead]",
                         action="store", default="binary")
-    parser.add_argument("--target-help", dest="show_target_help",
+    parser.add_argument("--help-pragmas", "--pragma-help", "--pragmas-help",
+                        "--help-annotations", "--annotation-help", "--annotations-help",
+                        dest="help_pragmas", action="store_true", default=False,
+                        help = "Print the documentation about supported annotations/pragmas and exit.")
+    parser.add_argument("--help-targets", "--target-help", "--targets-help",
+                        dest="show_target_help",
                         help="Display target specific command line options.",
                         action="store_true", default=False)
     parser.add_argument("-S", dest="run_till_assembler",
                         help="Only run the preprocess and compilation steps",
                         action="store_true", default=False)
     parser.add_argument("--std", "-x", dest="language",
-                        choices = ["p4-14", "p4-16"],
+                        choices = ["p4-14", "p4_14", "p4-16", "p4_16"],
                         help="Treat subsequent input files as having type language.",
                         action="store", default="p4-16")
 
@@ -166,6 +171,10 @@ def main():
     user_defined_version = os.environ.get('P4C_DEFAULT_VERSION')
     if user_defined_version != None:
         opts.language = user_defined_version
+    # accept multiple ways of specifying which language, and ensure that it is a consistent
+    # string from now on.
+    if opts.language == "p4_14": opts.language = "p4-14"
+    if opts.language == "p4_16": opts.language = "p4-16"
 
     user_defined_target = os.environ.get('P4C_DEFAULT_TARGET')
     if user_defined_target != None:
@@ -184,20 +193,30 @@ def main():
         print display_supported_targets(cfg)
         sys.exit(0)
 
+    # When using --help-* options, we don't necessarily need to pass an input file
+    # However, by default the driver checks the input and fails if it does not exist.
+    # Also, loading the backend configuration files requires a source file to be set,
+    # so in that case, we set the input to dummy.p4 and expect that the backend itself
+    # will do its printing and ignore the input file.
+    # If not, the compiler will error out anyway.
+    checkInput = not opts.help_pragmas
+
     input_specified = False
     if opts.source_file:
         input_specified = True
     if (os.environ['P4C_BUILD_TYPE'] == "DEVELOPER"):
         if opts.json_source:
             input_specified = True
-    if not input_specified:
+    if checkInput and not input_specified:
         parser.error('No input specified.')
+    elif not checkInput:
+        opts.source_file = "dummy.p4"
 
     if (os.environ['P4C_BUILD_TYPE'] == "DEVELOPER"):
         if opts.json_source:
             opts.source_file = opts.json_source
 
-    if not os.path.isfile(opts.source_file):
+    if checkInput and not os.path.isfile(opts.source_file):
         print >> sys.stderr, 'Input file ' + opts.source_file + ' does not exist'
         sys.exit(1)