[LIB]: Add conf->expand_pointers

So that we can expand pointer types, useful for ABI signature checking. And to
fully browse a type, when using --expand_types is also of interest.

I have yet to disable printing the offsets when expanding pointers, where the
information is not useful at all, for now just ignore it, it gets back to a
sane state in the next field, after the pointer type expansion.

Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>

dwarves.c

@@ -299,6 +299,7 @@ static void tag__init(struct tag *self, Dwarf_Die *die)
 	self->decl_file = strings__add(dwarf_decl_file(die));
 	dwarf_decl_line(die, &decl_line);
 	self->decl_line = decl_line;
+	self->recursivity_level = 0;
 }
 
 static struct tag *tag__new(Dwarf_Die *die)
@@ -1276,14 +1277,44 @@ static size_t type__fprintf(struct tag *type, const struct cu *cu,
 			    FILE *fp)
 {
 	char tbf[128];
+	char namebf[256];
 	struct type *ctype;
 	struct conf_fprintf tconf;
 	size_t printed = 0;
+	int expand_types = conf->expand_types;
 
 	if (type == NULL)
 		goto out_type_not_found;
 
-	if (conf->expand_types) {
+	if (conf->expand_pointers) {
+		int nr_indirections = 0;
+
+		while (type->tag == DW_TAG_pointer_type && type->type != 0) {
+			type = cu__find_tag_by_id(cu, type->type);
+			if (type == NULL)
+				goto out_type_not_found;
+			++nr_indirections;
+		}
+
+		if (nr_indirections > 0) {
+			const size_t len = strlen(name);
+			if (len + nr_indirections >= sizeof(namebf))
+				goto out_type_not_found;
+			memset(namebf, '*', nr_indirections);
+			memcpy(namebf + nr_indirections, name, len);
+			namebf[len + nr_indirections] = '\0';
+			name = namebf;
+		}
+
+		expand_types = nr_indirections;
+
+		/* Avoid loops */
+		if (type->recursivity_level != 0)
+			expand_types = 0;
+		++type->recursivity_level;
+	}
+
+	if (expand_types) {
 		int typedef_expanded = 0;
 
 		while (type->tag == DW_TAG_typedef) {
@@ -1342,7 +1373,7 @@ static size_t type__fprintf(struct tag *type, const struct cu *cu,
 	case DW_TAG_structure_type:
 		ctype = tag__type(type);
 
-		if (type__name(ctype, cu) != NULL && !conf->expand_types)
+		if (type__name(ctype, cu) != NULL && !expand_types)
 			printed += fprintf(fp, "struct %-*s %s",
 					   conf->type_spacing - 7,
 					   type__name(ctype, cu), name);
@@ -1353,7 +1384,7 @@ static size_t type__fprintf(struct tag *type, const struct cu *cu,
 	case DW_TAG_union_type:
 		ctype = tag__type(type);
 
-		if (type__name(ctype, cu) != NULL && !conf->expand_types)
+		if (type__name(ctype, cu) != NULL && !expand_types)
 			printed += fprintf(fp, "union %-*s %s",
 					   conf->type_spacing - 6,
 					   type__name(ctype, cu), name);
@@ -1372,6 +1403,9 @@ static size_t type__fprintf(struct tag *type, const struct cu *cu,
 		break;
 	}
 out:
+	if (conf->expand_types)
+		--type->recursivity_level;
+
 	return printed;
 out_type_not_found:
 	printed = fprintf(fp, "%-*s %s", conf->type_spacing, "<ERROR>", name);
@@ -2458,7 +2492,7 @@ static size_t namespace__fprintf(const struct tag *tself, const struct cu *cu,
 	return printed + fprintf(fp, "}");
 }
 
-size_t tag__fprintf(const struct tag *self, const struct cu *cu,
+size_t tag__fprintf(struct tag *self, const struct cu *cu,
 		    const struct conf_fprintf *conf, FILE *fp)
 {
 	size_t printed = 0;
@@ -2488,6 +2522,9 @@ size_t tag__fprintf(const struct tag *self, const struct cu *cu,
 			tconf.type_spacing = 26;
 	}
 
+	if (pconf->expand_types)
+		++self->recursivity_level;
+
 	if (pconf->show_decl_info) {
 		printed += fprintf(fp, "%.*s", pconf->indent, tabs);
 		printed += tag__fprintf_decl_info(self, fp);
@@ -2533,6 +2570,9 @@ size_t tag__fprintf(const struct tag *self, const struct cu *cu,
 		++printed;
 	}
 
+	if (pconf->expand_types)
+		--self->recursivity_level;
+
 	return printed;
 }
 

dwarves.h

@@ -54,7 +54,8 @@ struct tag {
 	const char	 *decl_file;
 	uint16_t	 decl_line;
 	uint16_t	 tag;
-	uint32_t	 refcnt;
+	uint16_t	 refcnt;
+	uint16_t	 recursivity_level;
 };
 
 static inline int tag__is_enumeration(const struct tag *self)
@@ -410,6 +411,7 @@ struct conf_fprintf {
 	uint32_t   base_offset;
 	uint8_t	   indent;
 	uint8_t	   expand_types:1;
+	uint8_t	   expand_pointers:1;
 	uint8_t    rel_offset:1;
 	uint8_t	   emit_stats:1;
 	uint8_t	   suppress_comments:1;
@@ -430,7 +432,7 @@ extern size_t enumeration__fprintf(const struct tag *tag_self,
 extern size_t typedef__fprintf(const struct tag *tag_self, const struct cu *cu,
 			       const struct conf_fprintf *conf, FILE *fp);
 extern size_t tag__fprintf_decl_info(const struct tag *self, FILE *fp);
-extern size_t tag__fprintf(const struct tag *self, const struct cu *cu,
+extern size_t tag__fprintf(struct tag *self, const struct cu *cu,
 			   const struct conf_fprintf *conf, FILE *fp);
 
 extern const char *function__name(struct function *self, const struct cu *cu);

pahole.c

@@ -548,6 +548,11 @@ static const struct argp_option pahole__options[] = {
 		.key  = 'M',
 		.doc  = "show only the members that use space in the class layout",
 	},
+	{
+		.name = "expand_pointers",
+		.key  = 'p',
+		.doc  = "expand class pointer members",
+	},
 	{
 		.name = "sizes",
 		.key  = 's',
@@ -634,6 +639,7 @@ static error_t pahole__options_parser(int key, char *arg,
 		break;
 	case 'B': nr_bit_holes = atoi(arg);		break;
 	case 'E': conf.expand_types = 1;		break;
+	case 'p': conf.expand_pointers = 1;		break;
 	case 'r': conf.rel_offset = 1;			break;
 	case 'R': reorganize = 1;			break;
 	case 'S': show_reorg_steps = 1;			break;