perf symbols: Record whether a symbol is an alias for an IFUNC symbol

To assist with synthesizing plt symbols for IFUNCs, record whether a
symbol is an alias of an IFUNC symbol.
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230131131625.6964-5-adrian.hunter@intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/symbol.c

@@ -201,10 +201,14 @@ void symbols__fixup_duplicate(struct rb_root_cached *symbols)
 			continue;
 
 		if (choose_best_symbol(curr, next) == SYMBOL_A) {
+			if (next->type == STT_GNU_IFUNC)
+				curr->ifunc_alias = true;
 			rb_erase_cached(&next->rb_node, symbols);
 			symbol__delete(next);
 			goto again;
 		} else {
+			if (curr->type == STT_GNU_IFUNC)
+				next->ifunc_alias = true;
 			nd = rb_next(&curr->rb_node);
 			rb_erase_cached(&curr->rb_node, symbols);
 			symbol__delete(curr);

tools/perf/util/symbol.h

@@ -64,6 +64,8 @@ struct symbol {
 	u8		inlined:1;
 	/** Has symbol__annotate2 been performed. */
 	u8		annotate2:1;
+	/** Symbol is an alias of an STT_GNU_IFUNC */
+	u8		ifunc_alias:1;
 	/** Architecture specific. Unused except on PPC where it holds st_other. */
 	u8		arch_sym;
 	/** The name of length namelen associated with the symbol. */