gendwarfksyms: Expand subroutine_type

Add support for expanding DW_TAG_subroutine_type and the parameters
in DW_TAG_formal_parameter. Use this to also expand subprograms.

Example output with --debug:

  subprogram(
    formal_parameter base_type usize byte_size(8),
    formal_parameter base_type usize byte_size(8),
  )
  -> base_type void;

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>

Author: samitolvanen

scripts/gendwarfksyms/dwarf.c

@@ -210,6 +210,15 @@ DEFINE_PROCESS_UDATA_ATTRIBUTE(alignment)
 DEFINE_PROCESS_UDATA_ATTRIBUTE(byte_size)
 DEFINE_PROCESS_UDATA_ATTRIBUTE(encoding)
 
+/* Match functions -- die_match_callback_t */
+#define DEFINE_MATCH(type)                                     \
+	static bool match_##type##_type(Dwarf_Die *die)        \
+	{                                                      \
+		return dwarf_tag(die) == DW_TAG_##type##_type; \
+	}
+
+DEFINE_MATCH(formal_parameter)
+
 bool match_all(Dwarf_Die *die)
 {
 	return true;
@@ -247,6 +256,25 @@ static int process_type_attr(struct state *state, struct die *cache,
 	return check(process(state, cache, "base_type void"));
 }
 
+/* Comma-separated with DW_AT_type */
+static int __process_list_type(struct state *state, struct die *cache,
+			       Dwarf_Die *die, const char *type)
+{
+	check(process(state, cache, type));
+	check(process_type_attr(state, cache, die));
+	check(process(state, cache, ","));
+	return check(process_linebreak(cache, 0));
+}
+
+#define DEFINE_PROCESS_LIST_TYPE(type)                                      \
+	static int process_##type##_type(struct state *state,               \
+					 struct die *cache, Dwarf_Die *die) \
+	{                                                                   \
+		return __process_list_type(state, cache, die, #type " ");   \
+	}
+
+DEFINE_PROCESS_LIST_TYPE(formal_parameter)
+
 /* Container types with DW_AT_type */
 static int __process_type(struct state *state, struct die *cache,
 			  Dwarf_Die *die, const char *type)
@@ -281,6 +309,29 @@ DEFINE_PROCESS_TYPE(shared)
 DEFINE_PROCESS_TYPE(volatile)
 DEFINE_PROCESS_TYPE(typedef)
 
+static int __process_subroutine_type(struct state *state, struct die *cache,
+				     Dwarf_Die *die, const char *type)
+{
+	check(process(state, cache, type));
+	check(process(state, cache, "("));
+	check(process_linebreak(cache, 1));
+	/* Parameters */
+	check(process_die_container(state, cache, die, process_type,
+				    match_formal_parameter_type));
+	check(process_linebreak(cache, -1));
+	check(process(state, cache, ")"));
+	process_linebreak(cache, 0);
+	/* Return type */
+	check(process(state, cache, "-> "));
+	return check(process_type_attr(state, cache, die));
+}
+
+static int process_subroutine_type(struct state *state, struct die *cache,
+				   Dwarf_Die *die)
+{
+	return check(__process_subroutine_type(state, cache, die,
+					       "subroutine_type"));
+}
 static int process_base_type(struct state *state, struct die *cache,
 			     Dwarf_Die *die)
 {
@@ -358,8 +409,11 @@ static int process_type(struct state *state, struct die *parent, Dwarf_Die *die)
 	PROCESS_TYPE(rvalue_reference)
 	PROCESS_TYPE(shared)
 	PROCESS_TYPE(volatile)
+	/* Subtypes */
+	PROCESS_TYPE(formal_parameter)
 	/* Other types */
 	PROCESS_TYPE(base)
+	PROCESS_TYPE(subroutine)
 	PROCESS_TYPE(typedef)
 	default:
 		debug("unimplemented type: %x", tag);
@@ -379,7 +433,8 @@ static int process_type(struct state *state, struct die *parent, Dwarf_Die *die)
  */
 static int process_subprogram(struct state *state, Dwarf_Die *die)
 {
-	return check(process(state, NULL, "subprogram;\n"));
+	check(__process_subroutine_type(state, NULL, die, "subprogram"));
+	return check(process(state, NULL, ";\n"));
 }
 
 static int process_variable(struct state *state, Dwarf_Die *die)

scripts/gendwarfksyms/gendwarfksyms.h

@@ -59,6 +59,7 @@ extern bool debug;
 #define checkp(expr) __check(expr, __res < 0, __res)
 
 /* Consistent aliases (DW_TAG_<type>_type) for DWARF tags */
+#define DW_TAG_formal_parameter_type DW_TAG_formal_parameter
 #define DW_TAG_typedef_type DW_TAG_typedef
 
 /*