[PATCH 3/4] perf probe: Enable --range option according to libdw version

[He Kuang]

The option --range uses functions in libdw (elfutils version >= 1.57),
this patch check if elfutils version meets the requirements before
enable this feature, so that perf can be built with old libdw.

Reported-by: Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx>
Signed-off-by: He Kuang <hekuang@xxxxxxxxxx>
---
 tools/perf/builtin-probe.c  |  2 ++
 tools/perf/util/dwarf-aux.c |  2 ++
 tools/perf/util/dwarf-aux.h | 13 ++++++++++++-
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
index 1272559..2760c06 100644
--- a/tools/perf/builtin-probe.c
+++ b/tools/perf/builtin-probe.c
@@ -372,8 +372,10 @@ __cmd_probe(int argc, const char **argv, const char *prefix __maybe_unused)
 		     "Show accessible variables on PROBEDEF", opt_show_vars),
 	OPT_BOOLEAN('\0', "externs", &probe_conf.show_ext_vars,
 		    "Show external variables too (with --vars only)"),
+#if _ELFUTILS_PREREQ(0, 157)
 	OPT_BOOLEAN('\0', "range", &probe_conf.show_location_range,
 		"Show variables location range in scope (with --vars only)"),
+#endif
 	OPT_STRING('k', "vmlinux", &symbol_conf.vmlinux_name,
 		   "file", "vmlinux pathname"),
 	OPT_STRING('s', "source", &symbol_conf.source_prefix,
diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
index 57f3ef4..2cb4c82 100644
--- a/tools/perf/util/dwarf-aux.c
+++ b/tools/perf/util/dwarf-aux.c
@@ -950,6 +950,7 @@ int die_get_varname(Dwarf_Die *vr_die, struct strbuf *buf)
 	return 0;
 }
 
+#if _ELFUTILS_PREREQ(0, 157)
 /**
  * die_get_var_innermost_scope - Get innermost scope range of given variable DIE
  * @sp_die: a subprogram DIE
@@ -1071,3 +1072,4 @@ int die_get_var_range(Dwarf_Die *sp_die, Dwarf_Die *vr_die, struct strbuf *buf)
 
 	return ret;
 }
+#endif /* _ELFUTILS_PREREQ(0, 157) */
diff --git a/tools/perf/util/dwarf-aux.h b/tools/perf/util/dwarf-aux.h
index c42ec36..ade0c50 100644
--- a/tools/perf/util/dwarf-aux.h
+++ b/tools/perf/util/dwarf-aux.h
@@ -125,6 +125,17 @@ extern int die_get_typename(Dwarf_Die *vr_die, struct strbuf *buf);
 
 /* Get the name and type of given variable DIE, stored as "type\tname" */
 extern int die_get_varname(Dwarf_Die *vr_die, struct strbuf *buf);
+#if _ELFUTILS_PREREQ(0, 157)
 extern int die_get_var_range(Dwarf_Die *sp_die, Dwarf_Die *vr_die,
-			struct strbuf *buf);
+			     struct strbuf *buf);
+#else
+static inline
+int die_get_var_range(Dwarf_Die *sp_die __maybe_unused,
+		      Dwarf_Die *vr_die __maybe_unused,
+		      struct strbuf *buf __maybe_unused)
+{
+	return -ENOTSUP;
+}
+
+#endif /* _ELFUTILS_PREREQ(0, 157) */
 #endif
-- 
1.8.5.2

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