perf tools: Preserve identifier id in OCaml demangler

Some OCaml developers reported that this bit of information is sometimes
useful for disambiguating functions for which the OCaml compiler assigns
the same name, e.g. nested or inlined functions.

Signed-off-by: Fabian Hemmer <copy@copy.sh>
Link: http://lore.kernel.org/lkml/20210226075223.p3s5oz4jbxwnqjtv@nyu
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/demangle-ocaml-test.c

@@ -19,11 +19,11 @@ int test__demangle_ocaml(struct test *test __maybe_unused, int subtest __maybe_u
 		{ "main",
 		  NULL },
 		{ "camlStdlib__array__map_154",
-		  "Stdlib.array.map" },
+		  "Stdlib.array.map_154" },
 		{ "camlStdlib__anon_fn$5bstdlib$2eml$3a334$2c0$2d$2d54$5d_1453",
-		  "Stdlib.anon_fn[stdlib.ml:334,0--54]" },
+		  "Stdlib.anon_fn[stdlib.ml:334,0--54]_1453" },
 		{ "camlStdlib__bytes__$2b$2b_2205",
-		  "Stdlib.bytes.++" },
+		  "Stdlib.bytes.++_2205" },
 	};
 
 	for (i = 0; i < ARRAY_SIZE(test_cases); i++) {

tools/perf/util/demangle-ocaml.c

@@ -64,17 +64,5 @@ ocaml_demangle_sym(const char *sym)
 	}
 	result[j] = '\0';
 
-	/* scan backwards to remove an "_" followed by decimal digits */
-	if (j != 0 && isdigit(result[j - 1])) {
-		while (--j) {
-			if (!isdigit(result[j])) {
-				break;
-			}
-		}
-		if (result[j] == '_') {
-			result[j] = '\0';
-		}
-	}
-
 	return result;
 }