The "artificial" flag corresponds directly to DW_AT_artificial, which
indicates a compiler-generated variable (e.g. __func__) which shouldn't
be included in the output.
The "top_level" flag is intended to be a better proxy for global scoped
variables. Currently, the DWARF loader examines the DWARF location
expression, and if the location is found to be at a constant memory
address (not stack, register, etc), then the variable is assumed to be
globally scoped. However, this includes a variety of variables that
aren't truly globally scoped: most commonly, static variables in
functions definitions. Their locations may be static, but they're not
globally accessible in any useful way.
These flags will be used by the BTF encoder to select global variables.
Signed-off-by: Stephen Brennan <stephen.s.brennan@xxxxxxxxxx>
---
dwarf_loader.c | 12 +++++++-----
dwarves.h | 2 ++
2 files changed, 9 insertions(+), 5 deletions(-)
diff --git a/dwarf_loader.c b/dwarf_loader.c
index 065ed4d..d162214 100644
--- a/dwarf_loader.c
+++ b/dwarf_loader.c
@@ -730,7 +730,7 @@ const char *variable__scope_str(const struct variable *var)
return "unknown";
}
-static struct variable *variable__new(Dwarf_Die *die, struct cu *cu, struct conf_load *conf)
+static struct variable *variable__new(Dwarf_Die *die, struct cu *cu, struct conf_load *conf, int top_level)
{
bool has_specification = dwarf_hasattr(die, DW_AT_specification);
struct variable *var = tag__alloc(cu, sizeof(*var));
@@ -743,6 +743,8 @@ static struct variable *variable__new(Dwarf_Die *die, struct cu *cu, struct conf
/* non-defining declaration of an object */
var->declaration = dwarf_hasattr(die, DW_AT_declaration);
var->has_specification = has_specification;
+ var->artificial = dwarf_hasattr(die, DW_AT_artificial);
+ var->top_level = top_level;
var->scope = VSCOPE_UNKNOWN;
INIT_LIST_HEAD(&var->annots);
var->ip.addr = 0;
@@ -1767,9 +1769,9 @@ static struct tag *die__create_new_label(Dwarf_Die *die,
return &label->ip.tag;
}
-static struct tag *die__create_new_variable(Dwarf_Die *die, struct cu *cu, struct conf_load *conf)
+static struct tag *die__create_new_variable(Dwarf_Die *die, struct cu *cu, struct conf_load *conf, int top_level)
{
- struct variable *var = variable__new(die, cu, conf);
+ struct variable *var = variable__new(die, cu, conf, top_level);
if (var == NULL || add_child_llvm_annotations(die, -1, conf, &var->annots))
return NULL;
@@ -2243,7 +2245,7 @@ static int die__process_function(Dwarf_Die *die, struct ftype *ftype,
tag = die__create_new_parameter(die, ftype, lexblock, cu, conf, param_idx++);
break;
case DW_TAG_variable:
- tag = die__create_new_variable(die, cu, conf);
+ tag = die__create_new_variable(die, cu, conf, 0);
if (tag == NULL)
goto out_enomem;
lexblock__add_variable(lexblock, tag__variable(tag));
@@ -2367,7 +2369,7 @@ static struct tag *__die__process_tag(Dwarf_Die *die, struct cu *cu,
case DW_TAG_union_type:
tag = die__create_new_union(die, cu, conf); break;
case DW_TAG_variable:
- tag = die__create_new_variable(die, cu, conf); break;
+ tag = die__create_new_variable(die, cu, conf, top_level); break;
case DW_TAG_constant: // First seen in a Go CU
tag = die__create_new_constant(die, cu, conf); break;
default:
diff --git a/dwarves.h b/dwarves.h
index f2d3988..0fede91 100644
--- a/dwarves.h
+++ b/dwarves.h
@@ -848,6 +848,8 @@ struct variable {
uint8_t external:1;
uint8_t declaration:1;
uint8_t has_specification:1;
+ uint8_t artificial:1;
+ uint8_t top_level:1;
enum vscope scope;
struct location location;
struct hlist_node tool_hnode;
--
2.43.5
