perf symbols: Add dso__insert_symbol function

The current method for inserting symbols is to use the symbols__insert()
function. However symbols__insert() does not update the dso symbol
cache.  This causes problems in the following scenario:

1. symbol not found at addr using dso__find_symbol

2. symbol inserted at addr using the existing symbols__insert function

3. symbol still not found at addr using dso__find_symbol() because cache isn't
   updated. This is undesired behavior.

The undesired behavior in (3) is addressed by creating a new function,
dso__insert_symbol() to both insert the symbol and update the symbol
cache if necessary.

If dso__insert_symbol() is used in (2) instead of symbols__insert(),
then the undesired behavior in (3) is avoided.

Signed-off-by: Chris Phlipot <cphlipot0@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1462937209-6032-2-git-send-email-cphlipot0@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 2946295..21af8e8 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -413,6 +413,18 @@
 	}
 }
 
+void dso__insert_symbol(struct dso *dso, enum map_type type, struct symbol *sym)
+{
+	symbols__insert(&dso->symbols[type], sym);
+
+	/* update the symbol cache if necessary */
+	if (dso->last_find_result[type].addr >= sym->start &&
+	    (dso->last_find_result[type].addr < sym->end ||
+	    sym->start == sym->end)) {
+		dso->last_find_result[type].symbol = sym;
+	}
+}
+
 struct symbol *dso__find_symbol(struct dso *dso,
 				enum map_type type, u64 addr)
 {