perf diff: Refactor diff displacement possition info

Moving the position calculation into the diff command, so the position
as prepared inside struct hist_entry data and there's no need to compute
in the output display path.

Removing 'displacement' from struct perf_hpp as it is no longer needed.

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1349354994-17853-3-git-send-email-namhyung@kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/ui/hist.c b/tools/perf/ui/hist.c
index e3f8cd4..55b9ca8 100644
--- a/tools/perf/ui/hist.c
+++ b/tools/perf/ui/hist.c
@@ -244,13 +244,15 @@
 }
 
 static int hpp__entry_displ(struct perf_hpp *hpp,
-			    struct hist_entry *he __maybe_unused)
+			    struct hist_entry *he)
 {
+	struct hist_entry *pair = he->pair;
+	long displacement = pair ? pair->position - he->position : 0;
 	const char *fmt = symbol_conf.field_sep ? "%s" : "%6.6s";
 	char buf[32] = " ";
 
-	if (hpp->displacement)
-		scnprintf(buf, sizeof(buf), "%+4ld", hpp->displacement);
+	if (displacement)
+		scnprintf(buf, sizeof(buf), "%+4ld", displacement);
 
 	return scnprintf(hpp->buf, hpp->size, fmt, buf);
 }