Hi.
I've started working on introduction of a new shared library for GCOV.
Justification is PR84107 where libgcov does not properly work properly
for multiple DSOs.
I created a working prototype and as it's my first time I'm creating a shared
library in GCC, I've got multiple questions:
1) currently both libgcov.so and libgcov.a are installed in an install folder
and
when using: gcc main.c -lcov the static one is preferred.
Do we need an option -static-libgcov?
2) I created libgcc/config/t-libgcov-elf file. It's currently added just for:
x86_64-*-linux*)
What's the right placement of content added to t-libgcov-elf?
3) Should I come up with a symbol versioning of the libgcov API?
I'm attaching current patch, so any comment is welcomed.
Thanks,
Martin
>From 3ffb36795ea6999be34ce079c435b391d5db62cb Mon Sep 17 00:00:00 2001
From: marxin <mli...@suse.cz>
Date: Fri, 3 Aug 2018 11:14:15 +0200
Subject: [PATCH] Add libgcov.so: work in progress.
---
libgcc/Makefile.in | 18 +++++++++++++-
libgcc/config.host | 2 +-
libgcc/config/t-libgcov-elf | 48 +++++++++++++++++++++++++++++++++++++
libgcc/libgcov-profiler.c | 6 ++---
libgcc/libgcov.h | 14 +++++------
5 files changed, 76 insertions(+), 12 deletions(-)
create mode 100644 libgcc/config/t-libgcov-elf
diff --git a/libgcc/Makefile.in b/libgcc/Makefile.in
index 0c5b264f717..530bc0dced4 100644
--- a/libgcc/Makefile.in
+++ b/libgcc/Makefile.in
@@ -944,7 +944,7 @@ libgcc.a libgcov.a libunwind.a libgcc_eh.a:
all: libgcc.a
ifeq ($(enable_gcov),yes)
-all: libgcov.a
+all: libgcov.a libgcov$(SHLIB_EXT)
endif
ifneq ($(LIBUNWIND),)
@@ -1006,6 +1006,18 @@ libunwind$(SHLIB_EXT): $(libunwind-s-objects) $(extra-parts)
@shlib_base_name@,libunwind,$(subst \
@shlib_slibdir_qual@,$(MULTIOSSUBDIR),$(SHLIBUNWIND_LINK))))))
+libgcov$(SHLIB_EXT): $(libgcov-objects) libgcc_s$(SHLIB_EXT)
+ # @multilib_flags@ is still needed because this may use
+ # $(GCC_FOR_TARGET) and $(LIBGCC2_CFLAGS) directly.
+ # @multilib_dir@ is not really necessary, but sometimes it has
+ # more uses than just a directory name.
+ $(mkinstalldirs) $(MULTIDIR)
+ $(subst @multilib_flags@,$(CFLAGS) -B./,$(subst \
+ @multilib_dir@,$(MULTIDIR),$(subst \
+ @shlib_objs@,$(objects),$(subst \
+ @shlib_base_name@,libgcov,$(subst \
+ @shlib_slibdir_qual@,$(MULTIOSSUBDIR),$(SHLIBGCOV_LINK))))))
+
endif
# Build the standard GCC startfiles and endfiles.
@@ -1172,6 +1184,10 @@ ifeq ($(enable_gcov),yes)
$(INSTALL_DATA) libgcov.a $(DESTDIR)$(inst_libdir)/
chmod 644 $(DESTDIR)$(inst_libdir)/libgcov.a
$(RANLIB) $(DESTDIR)$(inst_libdir)/libgcov.a
+
+ $(subst @multilib_dir@,$(MULTIDIR),$(subst \
+ @shlib_base_name@,libgcov,$(subst \
+ @shlib_slibdir_qual@,$(MULTIOSSUBDIR),$(SHLIBGCOV_INSTALL))))
endif
parts="$(INSTALL_PARTS)"; \
diff --git a/libgcc/config.host b/libgcc/config.host
index 18cabaf24f6..dca583b8110 100644
--- a/libgcc/config.host
+++ b/libgcc/config.host
@@ -659,7 +659,7 @@ i[34567]86-*-kfreebsd*-gnu | i[34567]86-*-gnu* | i[34567]86-*-kopensolaris*-gnu)
;;
x86_64-*-linux*)
extra_parts="$extra_parts crtprec32.o crtprec64.o crtprec80.o crtfastmath.o"
- tmake_file="${tmake_file} i386/t-crtpc t-crtfm i386/t-crtstuff t-dfprules"
+ tmake_file="${tmake_file} i386/t-crtpc t-crtfm i386/t-crtstuff t-dfprulesi t-libgcov-elf"
tm_file="${tm_file} i386/elf-lib.h"
md_unwind_header=i386/linux-unwind.h
;;
diff --git a/libgcc/config/t-libgcov-elf b/libgcc/config/t-libgcov-elf
new file mode 100644
index 00000000000..19ef3db47ab
--- /dev/null
+++ b/libgcc/config/t-libgcov-elf
@@ -0,0 +1,48 @@
+# Copyright (C) 2004-2018 Free Software Foundation, Inc.
+#
+# This file is part of GCC.
+#
+# GCC is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3, or (at your option)
+# any later version.
+#
+# GCC is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with GCC; see the file COPYING3. If not see
+# <http://www.gnu.org/licenses/>.
+
+# Build libunwind for ELF with the GNU linker.
+
+SHLIB_SOLINK = @shlib_base_name@.so
+SHLIB_OBJS = @shlib_objs@
+SHLIB_DIR = @multilib_dir@
+SHLIB_SLIBDIR_QUAL = @shlib_slibdir_qual@
+
+SHLIBGCOV_SOVERSION = 1
+SHLIBGCOV_SONAME = @shlib_base_name@.so.$(SHLIBGCOV_SOVERSION)
+
+SHLIBGCOV_LINK = $(CC) $(LIBGCC2_CFLAGS) -shared \
+ -nodefaultlibs -Wl,-h,$(SHLIBGCOV_SONAME) \
+ -Wl,-z,text -Wl,-z,defs -o $(SHLIB_DIR)/$(SHLIBGCOV_SONAME).tmp \
+ @multilib_flags@ $(SHLIB_OBJS) -lc -lgcc && \
+ rm -f $(SHLIB_DIR)/$(SHLIB_SOLINK) && \
+ if [ -f $(SHLIB_DIR)/$(SHLIBGCOV_SONAME) ]; then \
+ mv -f $(SHLIB_DIR)/$(SHLIBGCOV_SONAME) \
+ $(SHLIB_DIR)/$(SHLIBGCOV_SONAME).backup; \
+ else true; fi && \
+ mv $(SHLIB_DIR)/$(SHLIBGCOV_SONAME).tmp \
+ $(SHLIB_DIR)/$(SHLIBGCOV_SONAME) && \
+ $(LN_S) $(SHLIBGCOV_SONAME) $(SHLIB_DIR)/$(SHLIB_SOLINK)
+
+SHLIBGCOV_INSTALL = \
+ $(SHELL) $(srcdir)/mkinstalldirs $(DESTDIR)$(slibdir)$(SHLIB_SLIBDIR_QUAL); \
+ $(INSTALL_DATA) $(SHLIB_DIR)/$(SHLIBGCOV_SONAME) \
+ $(DESTDIR)$(slibdir)$(SHLIB_SLIBDIR_QUAL)/$(SHLIBGCOV_SONAME); \
+ rm -f $(DESTDIR)$(slibdir)$(SHLIB_SLIBDIR_QUAL)/$(SHLIB_SOLINK); \
+ $(LN_S) $(SHLIBGCOV_SONAME) \
+ $(DESTDIR)$(slibdir)$(SHLIB_SLIBDIR_QUAL)/$(SHLIB_SOLINK)
diff --git a/libgcc/libgcov-profiler.c b/libgcc/libgcov-profiler.c
index 7e208d75d86..df20e73b4e1 100644
--- a/libgcc/libgcov-profiler.c
+++ b/libgcc/libgcov-profiler.c
@@ -271,12 +271,12 @@ __gcov_topn_value_profiler_body (gcov_type *counters, gcov_type value)
#if defined(HAVE_CC_TLS) && !defined (USE_EMUTLS)
__thread
#endif
-gcov_type *__gcov_indirect_call_topn_counters ATTRIBUTE_HIDDEN;
+gcov_type *__gcov_indirect_call_topn_counters;
#if defined(HAVE_CC_TLS) && !defined (USE_EMUTLS)
__thread
#endif
-void *__gcov_indirect_call_topn_callee ATTRIBUTE_HIDDEN;
+void *__gcov_indirect_call_topn_callee;
#ifdef TARGET_VTABLE_USES_DESCRIPTORS
#define VTABLE_USES_DESCRIPTORS 1
@@ -344,7 +344,7 @@ __gcov_indirect_call_profiler_v2 (gcov_type value, void* cur_func)
#ifdef L_gcov_time_profiler
/* Counter for first visit of each function. */
-gcov_type __gcov_time_profiler_counter ATTRIBUTE_HIDDEN;
+gcov_type __gcov_time_profiler_counter;
#endif
diff --git a/libgcc/libgcov.h b/libgcc/libgcov.h
index 21422873cf2..2e445b60bba 100644
--- a/libgcc/libgcov.h
+++ b/libgcc/libgcov.h
@@ -234,10 +234,10 @@ extern struct gcov_master __gcov_master;
extern void __gcov_dump_one (struct gcov_root *) ATTRIBUTE_HIDDEN;
/* Register a new object file module. */
-extern void __gcov_init (struct gcov_info *) ATTRIBUTE_HIDDEN;
+extern void __gcov_init (struct gcov_info *);
/* GCOV exit function registered via a static destructor. */
-extern void __gcov_exit (void) ATTRIBUTE_HIDDEN;
+extern void __gcov_exit (void);
/* Function to reset all counters to 0. Both externally visible (and
overridable) and internal version. */
@@ -247,19 +247,19 @@ extern void __gcov_reset_int (void) ATTRIBUTE_HIDDEN;
extern void __gcov_dump_int (void) ATTRIBUTE_HIDDEN;
/* The merge function that just sums the counters. */
-extern void __gcov_merge_add (gcov_type *, unsigned) ATTRIBUTE_HIDDEN;
+extern void __gcov_merge_add (gcov_type *, unsigned);
/* The merge function to select the minimum valid counter value. */
-extern void __gcov_merge_time_profile (gcov_type *, unsigned) ATTRIBUTE_HIDDEN;
+extern void __gcov_merge_time_profile (gcov_type *, unsigned);
/* The merge function to choose the most common value. */
-extern void __gcov_merge_single (gcov_type *, unsigned) ATTRIBUTE_HIDDEN;
+extern void __gcov_merge_single (gcov_type *, unsigned);
/* The merge function that just ors the counters together. */
-extern void __gcov_merge_ior (gcov_type *, unsigned) ATTRIBUTE_HIDDEN;
+extern void __gcov_merge_ior (gcov_type *, unsigned);
/* The merge function is used for topn indirect call counters. */
-extern void __gcov_merge_icall_topn (gcov_type *, unsigned) ATTRIBUTE_HIDDEN;
+extern void __gcov_merge_icall_topn (gcov_type *, unsigned);
/* The profiler functions. */
extern void __gcov_interval_profiler (gcov_type *, gcov_type, int, unsigned);
--
2.18.0
