[AMD Official Use Only]
Hello Bruno,
Thanks for reviewing the patch. It helps a lot. Along with my responses to your questions,
I have also attached the new patch with the changes. Please review.
> > --- a/gdb/dwarf2/read.c
> > +++ b/gdb/dwarf2/read.c
> Could you have these have tabs instead of 8 spaces? This goes for all
> indentations that have at least 8 spaces, by the way.
The entire patch is fixed by replacing 8 spaces with tabs.
> Since we are using imported declarations for more than just namespaces,
> this line is not necessarily true always. I think read_alias is going to have to do
> this, but a comment explaining why this case is different to the ones around
> it is welcome.
Added comment and set the flag to false if it is not namespace alias in read_alias function.
> Could you align the && with the second open parenthesis of the if line? This
> would make the whole expression easier to read.
Done.
> We require 2 spaces after the period, even at the end of comments.
Done for the entire patch.
> If you look at the original code, you see that if a new symbol was allocated,
> the return is always 1. I think having a possibility that the symbol can be
> allocated and we still return 0 could be a problem, but I am not sure.
> Regardless, by this point (and the if block above) we are pretty sure that the
> DIE is indeed a namespace variable or a variable alias, so returning 0 if we
> can't find the location seems wrong, but I am not a DWARF reader expert, so
> take my ramblings with a grain of salt.
I agree. The symbol is an imported declaration and a new symbol is created for the same.
I don't see any condition when it doesn't satisfy if or else condition and return false.
I have slightly modified the code so the location is either unresolved or fixed from
the import variable.
> why is this function returning 1 or 0 as boolean, instead of the
> function returning bool?
The function shall return bool instead of int. Fixed in the new patch.
> Is this "else" path being exercised anywhere? For this simple code:
>
> namespace n{
> int i;
> int j;
> void f(){ }
> }
>
> using n::i;
> using n::f;
>
> int var;
> extern int newvar __attribute__((alias("var")));
>
> int main(){
> i = 0;
> return 0;
> }
>
Imported declaration is emitted for namespace alias. If you declare as below
in the above program:
namespace m = n;
Clang will generate,
<1><23>: Abbrev Number: 2 (DW_TAG_namespace)
<24> DW_AT_name : (indexed string: 0x3): n
[...]
<1><59>: Abbrev Number: 7 (DW_TAG_imported_declaration)
<5a> DW_AT_decl_file : 0
<5b> DW_AT_decl_line : 7
<5c> DW_AT_import : <0x23> [Abbrev Number: 2 (DW_TAG_namespace)]
<60> DW_AT_name : (indexed string: 0xa): m
This is handled in the "else" path.
> > --- a/gdb/testsuite/gdb.base/symbol-alias.exp
> > +++ b/gdb/testsuite/gdb.base/symbol-alias.exp
> Since this is a new feature of clang and some tests run on quite old systems,
> could you try and detect the clang version, so you can have xfails for all
> aliases if the clang version doesn't emit this information?
Fixed. As of now, the clang version is checked for 14-0-0 and above. Can modify based on the version
in which this fix goes in finally. It should give 5 XFAILs for clang versions without the fix and 1 XFAIL
with the fix.
I have also added one more test point when the location information is missing (g_def_var2_alias2).
---------------
When clang emits the dwarf information of global alias variable
as DW_TAG_imported_declaration, gdb does not handle it. GDB reads
this tag as C++/fortran imported declaration (type alias, namespace
alias and fortran module). Added support to handle this tag as
alias variable.
This change fixes the failure in gdb.base/symbol-alias.exp testcase.
This testcase is also updated to test nested (recursive) alias.
Reviewed by: Bruno Larsen
---
gdb/dwarf2/read.c | 74 +++++++++++++++++--------
gdb/testsuite/gdb.base/symbol-alias.exp | 57 ++++++++++++++++++-
gdb/testsuite/gdb.base/symbol-alias2.c | 16 ++++++
3 files changed, 121 insertions(+), 26 deletions(-)
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index f9c942d91d3..6510dd94ac3 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -1132,6 +1132,10 @@ static void add_partial_subprogram (struct partial_die_info *pdi,
CORE_ADDR *lowpc, CORE_ADDR *highpc,
int need_pc, struct dwarf2_cu *cu);
+static void var_decode_location (struct attribute *attr,
+ struct symbol *sym,
+ struct dwarf2_cu *cu);
+
static unsigned int peek_abbrev_code (bfd *, const gdb_byte *);
static struct partial_die_info *load_partial_dies
@@ -1332,7 +1336,7 @@ static struct using_direct **using_directives (struct dwarf2_cu *cu);
static void read_import_statement (struct die_info *die, struct dwarf2_cu *);
-static int read_namespace_alias (struct die_info *die, struct dwarf2_cu *cu);
+static bool read_alias (struct die_info *die, struct dwarf2_cu *cu);
static struct type *read_module_type (struct die_info *die,
struct dwarf2_cu *cu);
@@ -9741,10 +9745,14 @@ process_die (struct die_info *die, struct dwarf2_cu *cu)
read_module (die, cu);
break;
case DW_TAG_imported_declaration:
+ /* If the imported declaration is for global variable alias,
+ this flag is set to false in read_alias function. */
cu->processing_has_namespace_info = true;
- if (read_namespace_alias (die, cu))
+ if (((cu->per_cu->lang == language_c)
+ || (cu->per_cu->lang == language_cplus))
+ && read_alias (die, cu))
break;
- /* The declaration is not a global namespace alias. */
+ /* The declaration is not a global namespace or variable alias. */
/* Fall through. */
case DW_TAG_imported_module:
cu->processing_has_namespace_info = true;
@@ -10212,18 +10220,20 @@ dwarf2_physname (const char *name, struct die_info *die, struct dwarf2_cu *cu)
return retval;
}
-/* Inspect DIE in CU for a namespace alias. If one exists, record
- a new symbol for it.
+#define MAX_NESTED_IMPORTED_DECLARATIONS 100
- Returns 1 if a namespace alias was recorded, 0 otherwise. */
+/* Inspect DIE in CU for a namespace alias or a variable
+ with alias attribute. If one exists, record a new symbol
+ for it.
-static int
-read_namespace_alias (struct die_info *die, struct dwarf2_cu *cu)
+ Returns 1 if an alias was recorded, 0 otherwise. */
+
+static bool
+read_alias (struct die_info *die, struct dwarf2_cu *cu)
{
struct attribute *attr;
- /* If the die does not have a name, this is not a namespace
- alias. */
+ /* The die must have a name for namespace or variable alias. */
attr = dwarf2_attr (die, DW_AT_name, cu);
if (attr != NULL)
{
@@ -10232,13 +10242,12 @@ read_namespace_alias (struct die_info *die, struct dwarf2_cu *cu)
struct dwarf2_cu *imported_cu = cu;
/* If the compiler has nested DW_AT_imported_declaration DIEs,
- keep inspecting DIEs until we hit the underlying import. */
-#define MAX_NESTED_IMPORTED_DECLARATIONS 100
+ keep inspecting DIEs until we hit the underlying import. */
for (num = 0; num < MAX_NESTED_IMPORTED_DECLARATIONS; ++num)
{
attr = dwarf2_attr (d, DW_AT_import, cu);
if (attr == NULL)
- break;
+ return false;
d = follow_die_ref (d, attr, &imported_cu);
if (d->tag != DW_TAG_imported_declaration)
@@ -10249,26 +10258,43 @@ read_namespace_alias (struct die_info *die, struct dwarf2_cu *cu)
{
complaint (_("DIE at %s has too many recursively imported "
"declarations"), sect_offset_str (d->sect_off));
- return 0;
+ return false;
}
if (attr != NULL)
{
struct type *type;
- sect_offset sect_off = attr->get_ref_die_offset ();
-
- type = get_die_type_at_offset (sect_off, cu->per_cu, cu->per_objfile);
- if (type != NULL && type->code () == TYPE_CODE_NAMESPACE)
+ if (d->tag == DW_TAG_variable)
{
- /* This declaration is a global namespace alias. Add
- a symbol for it whose type is the aliased namespace. */
- new_symbol (die, type, cu);
- return 1;
+ /* This declaration is a global variable alias. Add
+ a symbol for it whose type is same as aliased variable. */
+ type = die_type (d, imported_cu);
+ struct symbol *sym = new_symbol(die, type, cu);
+ attr = dwarf2_attr (d, DW_AT_location, imported_cu);
+ sym->set_aclass_index (LOC_UNRESOLVED);
+ if (attr != nullptr)
+ {
+ var_decode_location (attr, sym, cu);
+ }
+ /* Reset the flag as it is not a namespace alias. */
+ cu->processing_has_namespace_info = false;
+ return true;
+ }
+ else
+ {
+ sect_offset sect_off = attr->get_ref_die_offset ();
+ type = get_die_type_at_offset (sect_off, cu->per_cu, cu->per_objfile);
+ if (type != NULL && type->code () == TYPE_CODE_NAMESPACE)
+ {
+ /* This declaration is a global namespace alias. Add
+ a symbol for it whose type is the aliased namespace. */
+ new_symbol (die, type, cu);
+ return true;
+ }
}
}
}
-
- return 0;
+ return false;
}
/* Return the using directives repository (global or local?) to use in the
diff --git a/gdb/testsuite/gdb.base/symbol-alias.exp b/gdb/testsuite/gdb.base/symbol-alias.exp
index 2b53cc31053..253a60d5403 100644
--- a/gdb/testsuite/gdb.base/symbol-alias.exp
+++ b/gdb/testsuite/gdb.base/symbol-alias.exp
@@ -15,6 +15,7 @@
# along with this program. If not, see .
standard_testfile symbol-alias.c symbol-alias2.c
+set using_clang [test_compiler_info {clang-1[4-9]-*-*}]
if { [prepare_for_testing "failed to prepare" ${testfile} [list $srcfile $srcfile2]] } {
return -1
@@ -31,6 +32,58 @@ foreach f {"func" "func_alias"} {
}
# Variables.
-foreach v {"g_var_s" "g_var_s_alias"} {
- gdb_test "p $v" "= {field1 = 1, field2 = 2}"
+gdb_test "p g_var_s" "= {field1 = 1, field2 = 2}"
+foreach v {"g_var_s_alias" "g_var_s_alias2"} {
+ gdb_test_multiple "p $v" "p $v" {
+ -re " = {field1 = 1, field2 = 2}.*$gdb_prompt $" {
+ pass "print alias of variable $v"
+ }
+ -re ".*has unknown type; cast it to its declared type.*$gdb_prompt $" {
+ if { ! $using_clang } {
+ xfail "print alias variable $v"
+ } else {
+ fail "print alias variable $v"
+ }
+ }
+ }
+}
+
+# Static Variable.
+gdb_test "p g_var" " = 1"
+gdb_test_multiple "p g_var_alias" "p g_var_alias" {
+ -re " = 1.*$gdb_prompt $" {
+ pass "print alias of static variable"
+ }
+ -re ".*has unknown type; cast it to its declared type.*$gdb_prompt $" {
+ if { ! $using_clang } {
+ xfail "print alias of static variable"
+ } else {
+ fail "print alias of static variable"
+ }
+ }
+}
+
+# Deferred Variable.
+gdb_test "p g_def_var" " = 2"
+gdb_test_multiple "p g_def_var_alias" "p g_def_var_alias" {
+ -re " = 2.*$gdb_prompt $" {
+ pass "print alias of deferred variable"
+ }
+ -re ".*has unknown type; cast it to its declared type.*$gdb_prompt $" {
+ xfail "print alias of deferred variable"
+ }
+}
+
+# Alias of deferred Variable alias.
+gdb_test_multiple "p g_def_var2_alias2" "p g_def_var2_alias2" {
+ -re " = 3.*$gdb_prompt $" {
+ pass "print alias of alias of deferred variable"
+ }
+ -re ".*has unknown type; cast it to its declared type.*$gdb_prompt $" {
+ if { ! $using_clang } {
+ xfail "print alias of alias of deferred variable"
+ } else {
+ fail "print alias of alias of deferred variable"
+ }
+ }
}
diff --git a/gdb/testsuite/gdb.base/symbol-alias2.c b/gdb/testsuite/gdb.base/symbol-alias2.c
index 34f4e121e25..41d4b6a53e5 100644
--- a/gdb/testsuite/gdb.base/symbol-alias2.c
+++ b/gdb/testsuite/gdb.base/symbol-alias2.c
@@ -23,6 +23,8 @@ struct S
struct S g_var_s = { 1, 2 };
+static int g_var = 1;
+
#ifdef __cplusplus
/* So that the alias attribute below work without having to figure out
this function's mangled name. */
@@ -38,3 +40,17 @@ func (void)
struct S *func_alias (void) __attribute__ ((alias ("func")));
extern struct S g_var_s_alias __attribute__ ((alias ("g_var_s")));
+
+extern struct S g_var_s_alias2 __attribute__ ((alias ("g_var_s_alias")));
+
+extern int g_var_alias __attribute__ ((alias ("g_var")));
+
+extern int g_def_var_alias __attribute__ ((alias ("g_def_var")));
+
+int g_def_var = 2;
+
+extern int g_def_var2_alias __attribute__ ((alias ("g_def_var2")));
+
+int g_def_var2 = 3;
+
+extern int g_def_var2_alias2 __attribute__ ((alias ("g_def_var2_alias")));
--
Regards,
Kavitha