[PATCH 22/23] perf annotate-data: Add a cache for global variable types

[Namhyung Kim]

They are often searched by many different places.  Let's add a cache
for them to reduce the duplicate DWARF access.

Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
 tools/perf/util/annotate-data.c | 107 +++++++++++++++++++++++++++++++-
 tools/perf/util/annotate-data.h |   7 +++
 tools/perf/util/dso.c           |   2 +
 tools/perf/util/dso.h           |   6 +-
 4 files changed, 118 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/annotate-data.c b/tools/perf/util/annotate-data.c
index 633fe125fcd8..4b3184b7c799 100644
--- a/tools/perf/util/annotate-data.c
+++ b/tools/perf/util/annotate-data.c
@@ -433,6 +433,91 @@ static struct type_state_stack *findnew_stack_state(struct type_state *state,
 	return stack;
 }
 
+/* Maintain a cache for quick global variable lookup */
+struct global_var_entry {
+	struct rb_node node;
+	char *name;
+	u64 start;
+	u64 end;
+	u64 die_offset;
+};
+
+static int global_var_cmp(const void *_key, const struct rb_node *node)
+{
+	const u64 addr = (uintptr_t)_key;
+	struct global_var_entry *gvar;
+
+	gvar = rb_entry(node, struct global_var_entry, node);
+
+	if (gvar->start <= addr && addr < gvar->end)
+		return 0;
+	return gvar->start > addr ? -1 : 1;
+}
+
+static bool global_var_less(struct rb_node *node_a, const struct rb_node *node_b)
+{
+	struct global_var_entry *gvar_a, *gvar_b;
+
+	gvar_a = rb_entry(node_a, struct global_var_entry, node);
+	gvar_b = rb_entry(node_b, struct global_var_entry, node);
+
+	return gvar_a->start < gvar_b->start;
+}
+
+static struct global_var_entry *global_var__find(struct data_loc_info *dloc, u64 addr)
+{
+	struct dso *dso = map__dso(dloc->ms->map);
+	struct rb_node *node;
+
+	node = rb_find((void *)addr, &dso->global_vars, global_var_cmp);
+	if (node == NULL)
+		return NULL;
+
+	return rb_entry(node, struct global_var_entry, node);
+}
+
+static bool global_var__add(struct data_loc_info *dloc, u64 addr,
+			    const char *name, Dwarf_Die *type_die)
+{
+	struct dso *dso = map__dso(dloc->ms->map);
+	struct global_var_entry *gvar;
+	Dwarf_Word size;
+
+	if (dwarf_aggregate_size(type_die, &size) < 0)
+		return false;
+
+	gvar = malloc(sizeof(*gvar));
+	if (gvar == NULL)
+		return false;
+
+	gvar->name = strdup(name);
+	if (gvar->name == NULL) {
+		free(gvar);
+		return false;
+	}
+
+	gvar->start = addr;
+	gvar->end = addr + size;
+	gvar->die_offset = dwarf_dieoffset(type_die);
+
+	rb_add(&gvar->node, &dso->global_vars, global_var_less);
+	return true;
+}
+
+void global_var_type__tree_delete(struct rb_root *root)
+{
+	struct global_var_entry *gvar;
+
+	while (!RB_EMPTY_ROOT(root)) {
+		struct rb_node *node = rb_first(root);
+
+		rb_erase(node, root);
+		gvar = rb_entry(node, struct global_var_entry, node);
+		free(gvar->name);
+		free(gvar);
+	}
+}
+
 static bool get_global_var_info(struct data_loc_info *dloc, u64 addr,
 				const char **var_name, int *var_offset)
 {
@@ -467,14 +552,25 @@ static bool get_global_var_type(Dwarf_Die *cu_die, struct data_loc_info *dloc,
 	u64 pc;
 	int offset;
 	bool is_pointer = false;
-	const char *var_name;
+	const char *var_name = NULL;
+	struct global_var_entry *gvar;
 	Dwarf_Die var_die;
 
+	gvar = global_var__find(dloc, var_addr);
+	if (gvar) {
+		if (!dwarf_offdie(dloc->di->dbg, gvar->die_offset, type_die))
+			return false;
+
+		*var_offset = var_addr - gvar->start;
+		return true;
+	}
+
 	/* Try to get the variable by address first */
 	if (die_find_variable_by_addr(cu_die, var_addr, &var_die, &offset) &&
 	    check_variable(&var_die, type_die, offset, is_pointer) == 0) {
+		var_name = dwarf_diename(&var_die);
 		*var_offset = offset;
-		return true;
+		goto ok;
 	}
 
 	if (!get_global_var_info(dloc, var_addr, &var_name, var_offset))
@@ -485,9 +581,14 @@ static bool get_global_var_type(Dwarf_Die *cu_die, struct data_loc_info *dloc,
 	/* Try to get the name of global variable */
 	if (die_find_variable_at(cu_die, var_name, pc, &var_die) &&
 	    check_variable(&var_die, type_die, *var_offset, is_pointer) == 0)
-		return true;
+		goto ok;
 
 	return false;
+
+ok:
+	/* The address should point to the start of the variable */
+	global_var__add(dloc, var_addr - *var_offset, var_name, type_die);
+	return true;
 }
 
 /**
diff --git a/tools/perf/util/annotate-data.h b/tools/perf/util/annotate-data.h
index 1b5a152163b5..fe1e53d6e8c7 100644
--- a/tools/perf/util/annotate-data.h
+++ b/tools/perf/util/annotate-data.h
@@ -153,6 +153,9 @@ int annotated_data_type__update_samples(struct annotated_data_type *adt,
 /* Release all data type information in the tree */
 void annotated_data_type__tree_delete(struct rb_root *root);
 
+/* Release all global variable information in the tree */
+void global_var_type__tree_delete(struct rb_root *root);
+
 #else /* HAVE_DWARF_SUPPORT */
 
 static inline struct annotated_data_type *
@@ -175,6 +178,10 @@ static inline void annotated_data_type__tree_delete(struct rb_root *root __maybe
 {
 }
 
+static inline void global_var_type__tree_delete(struct rb_root *root __maybe_unused)
+{
+}
+
 #endif /* HAVE_DWARF_SUPPORT */
 
 #endif /* _PERF_ANNOTATE_DATA_H */
diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index 22fd5fa806ed..6e2a7198b382 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -1329,6 +1329,7 @@ struct dso *dso__new_id(const char *name, struct dso_id *id)
 		dso->inlined_nodes = RB_ROOT_CACHED;
 		dso->srclines = RB_ROOT_CACHED;
 		dso->data_types = RB_ROOT;
+		dso->global_vars = RB_ROOT;
 		dso->data.fd = -1;
 		dso->data.status = DSO_DATA_STATUS_UNKNOWN;
 		dso->symtab_type = DSO_BINARY_TYPE__NOT_FOUND;
@@ -1373,6 +1374,7 @@ void dso__delete(struct dso *dso)
 	dso->symbol_names_len = 0;
 	zfree(&dso->symbol_names);
 	annotated_data_type__tree_delete(&dso->data_types);
+	global_var_type__tree_delete(&dso->global_vars);
 
 	if (dso->short_name_allocated) {
 		zfree((char **)&dso->short_name);
diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h
index ce9f3849a773..2cdcd1e2ef8b 100644
--- a/tools/perf/util/dso.h
+++ b/tools/perf/util/dso.h
@@ -154,7 +154,8 @@ struct dso {
 	size_t		 symbol_names_len;
 	struct rb_root_cached inlined_nodes;
 	struct rb_root_cached srclines;
-	struct rb_root	data_types;
+	struct rb_root	 data_types;
+	struct rb_root	 global_vars;
 
 	struct {
 		u64		addr;
@@ -411,4 +412,7 @@ int dso__strerror_load(struct dso *dso, char *buf, size_t buflen);
 
 void reset_fd_limit(void);
 
+u64 dso__find_global_type(struct dso *dso, u64 addr);
+u64 dso__findnew_global_type(struct dso *dso, u64 addr, u64 offset);
+
 #endif /* __PERF_DSO */
-- 
2.44.0.291.gc1ea87d7ee-goog