Register the profile information in the specified section instead of using a
constructor/destructor. A pointer to the profile information generated by
-fprofile-arcs or -ftest-coverage is placed in the specified section for each
translation unit. This option disables the profile information registration
through a constructor and it disables the profile information processing
through a destructor.
I am not sure how I can test this option. One approach would be to assemble a
test file, then scan it and check that a .gcov_info section is present and no
__gcov_init() and __gcov_exit() calls are present. Is there an example for
this in the test suite?
gcc/
* gcc/common.opt (fprofile-info-section): New.
* gcc/coverage.c (build_gcov_info_var_registration): New.
(coverage_obj_init): Evaluate profile_info_section and use
build_gcov_info_var_registration().
* gcc/doc/invoke.texi (fprofile-info-section): Document.
* gcc/opts.c (common_handle_option): Process fprofile-info-section
option.
---
gcc/common.opt | 8 ++++++++
gcc/coverage.c | 28 ++++++++++++++++++++++++++--
gcc/doc/invoke.texi | 29 +++++++++++++++++++++++++++++
gcc/opts.c | 4 ++++
4 files changed, 67 insertions(+), 2 deletions(-)
diff --git a/gcc/common.opt b/gcc/common.opt
index 7d0e0d9c88a..114fe15e3c6 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -2268,6 +2268,14 @@ fprofile-generate=
Common Joined RejectNegative
Enable common options for generating profile info for profile feedback
directed optimizations, and set -fprofile-dir=.
+fprofile-info-section
+Common RejectNegative
+Register the profile information in the .gcov_info section instead of using a
constructor/destructor.
+
+fprofile-info-section=
+Common Joined RejectNegative Var(profile_info_section)
+Register the profile information in the specified section instead of using a
constructor/destructor.
+
fprofile-partial-training
Common Report Var(flag_profile_partial_training) Optimization
Do not assume that functions never executed during the train run are cold.
diff --git a/gcc/coverage.c b/gcc/coverage.c
index 7711412c3be..d299e48d591 100644
--- a/gcc/coverage.c
+++ b/gcc/coverage.c
@@ -1097,6 +1097,25 @@ build_gcov_exit_decl (void)
cgraph_build_static_cdtor ('D', dtor, priority);
}
+/* Generate the pointer to the gcov_info_var in a dedicated section. */
+
+static void
+build_gcov_info_var_registration (tree gcov_info_type)
+{
+ tree var = build_decl (BUILTINS_LOCATION,
+ VAR_DECL, NULL_TREE,
+ build_pointer_type (gcov_info_type));
+ TREE_STATIC (var) = 1;
+ TREE_READONLY (var) = 1;
+ char name_buf[32];
+ ASM_GENERATE_INTERNAL_LABEL (name_buf, "LPBX", 2);
+ DECL_NAME (var) = get_identifier (name_buf);
+ get_section (profile_info_section, SECTION_UNNAMED, NULL);
+ set_decl_section_name (var, profile_info_section);
+ DECL_INITIAL (var) = build_fold_addr_expr (gcov_info_var);
+ varpool_node::finalize_decl (var);
+}
+
/* Create the gcov_info types and object. Generate the constructor
function to call __gcov_init. Does not generate the initializer
for the object. Returns TRUE if coverage data is being emitted. */
@@ -1151,8 +1170,13 @@ coverage_obj_init (void)
ASM_GENERATE_INTERNAL_LABEL (name_buf, "LPBX", 0);
DECL_NAME (gcov_info_var) = get_identifier (name_buf);
- build_init_ctor (gcov_info_type);
- build_gcov_exit_decl ();
+ if (profile_info_section)
+ build_gcov_info_var_registration (gcov_info_type);
+ else
+ {
+ build_init_ctor (gcov_info_type);
+ build_gcov_exit_decl ();
+ }
return true;
}
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index d01beb248e1..e78c3c23ad2 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -564,6 +564,7 @@ Objective-C and Objective-C++ Dialects}.
@gccoptlist{-p -pg -fprofile-arcs --coverage -ftest-coverage @gol
-fprofile-abs-path @gol
-fprofile-dir=@var{path} -fprofile-generate -fprofile-generate=@var{path}
@gol
+-fprofile-info-section -fprofile-info-section=@var{name} @gol
-fprofile-note=@var{path} -fprofile-prefix-path=@var{path} @gol
-fprofile-update=@var{method} -fprofile-filter-files=@var{regex} @gol
-fprofile-exclude-files=@var{regex} @gol
@@ -14183,6 +14184,34 @@ the profile feedback data files. See
@option{-fprofile-dir}.
To optimize the program based on the collected profile information, use
@option{-fprofile-use}. @xref{Optimize Options}, for more information.
+@item -fprofile-info-section
+@itemx -fprofile-info-section=@var{name}
+@opindex fprofile-info-section
+
+Register the profile information in the specified section instead of using a
+constructor/destructor. The section name is @var{name} if it is specified,
+otherwise the section name defaults to @code{.gcov_info}. A pointer to the
+profile information generated by @option{-fprofile-arcs} or
+@option{-ftest-coverage} is placed in the specified section for each
+translation unit. This option disables the profile information registration
+through a constructor and it disables the profile information processing
+through a destructor. This option is not intended to be used in hosted
+environments such as GNU/Linux. It targets systems with limited resources
+which do not support constructors and destructors. The linker could collect
+the input sections in a continuous memory block and define start and end
+symbols. The runtime support could dump the profiling information registered
+in this linker set during program termination to a serial line for example. A
+GNU linker script example which defines a linker output section follows:
+
+@smallexample
+ .gcov_info :
+ {
+ PROVIDE (__gcov_info_start = .);
+ KEEP (*(.gcov_info))
+ PROVIDE (__gcov_info_end = .);
+ }
+@end smallexample
+
@item -fprofile-note=@var{path}
@opindex fprofile-note
diff --git a/gcc/opts.c b/gcc/opts.c
index 96291e89a49..fd6e669471e 100644
--- a/gcc/opts.c
+++ b/gcc/opts.c
@@ -2602,6 +2602,10 @@ common_handle_option (struct gcc_options *opts,
SET_OPTION_IF_UNSET (opts, opts_set, flag_ipa_bit_cp, value);
break;
+ case OPT_fprofile_info_section:
+ opts->x_profile_info_section = ".gcov_info";
+ break;
+
case OPT_fpatchable_function_entry_:
{
char *patch_area_arg = xstrdup (arg);
--
2.26.2
