[PATCH] gcov: Fix use of profile info section

[PATCH] gcov: Fix use of profile info section

[Sebastian Huber]

If the -fprofile-info-section is used, then the gcov information is registered
in a linker set.  This is done by build_gcov_info_var_registration().  The
compiler generated object placed in the section was not marked as referenced,
so once optimization was enabled, this object was optimized away.  Mark it as
referenced.

gcc/
	coverage.c (build_gcov_info_var_registration): Mark the object placed
	in the linker set as referenced so that it does not get optimized away.
---
 gcc/coverage.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/gcc/coverage.c b/gcc/coverage.c
index dfc8108d5d83..ac9a9fdad228 100644
--- a/gcc/coverage.c
+++ b/gcc/coverage.c
@@ -50,6 +50,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "auto-profile.h"
 #include "profile.h"
 #include "diagnostic.h"
+#include "varasm.h"
 
 #include "gcov-io.c"
 
@@ -1121,6 +1122,7 @@ build_gcov_info_var_registration (tree gcov_info_type)
   DECL_NAME (var) = get_identifier (name_buf);
   get_section (profile_info_section, SECTION_UNNAMED, NULL);
   set_decl_section_name (var, profile_info_section);
+  mark_decl_referenced (var);
   DECL_INITIAL (var) = build_fold_addr_expr (gcov_info_var);
   varpool_node::finalize_decl (var);
 }
-- 
2.26.2

Re: [PATCH] gcov: Fix use of profile info section

[Jeff Law]

On 7/14/2021 1:46 AM, Sebastian Huber wrote:
> If the -fprofile-info-section is used, then the gcov information is registered
> in a linker set.  This is done by build_gcov_info_var_registration().  The
> compiler generated object placed in the section was not marked as referenced,
> so once optimization was enabled, this object was optimized away.  Mark it as
> referenced.
>
> gcc/
> 	coverage.c (build_gcov_info_var_registration): Mark the object placed
> 	in the linker set as referenced so that it does not get optimized away.
OK
jeff