stdio: Remove the usage of $(fno-unit-at-a-time) for errlist.c

The errlist.c is built with -fno-toplevel-reorder to avoid compiler to
reorder the compat assembly directives due an assembler issue [1]
(fixed on 2.39).

This patch removes the compiler flags by split the compat symbol
generation in two phases.  First the _sys_errlist_internal internal
without any compat symbol directive is preprocessed to generate an
assembly source code.  This generate assembly is then used as input
on a platform agnostic errlist-data.S which then creates the compat
definitions.  This prevents compiler to move any compat directive
prior the _sys_errlist_internal definition itself.

Checked on a make check run-built-tests=no on all affected ABIs.

[1] https://sourceware.org/bugzilla/show_bug.cgi?id=29012

7 files changed, 89 insertions, 18 deletions

diff --git a/stdio-common/Makefile b/stdio-common/Makefile
index a1603e82fe..08bc998436 100644
--- a/stdio-common/Makefile
+++ b/stdio-common/Makefile
@@ -88,6 +88,7 @@ routines := \
 
 aux := \
   errlist \
+  errlist-data \
   errname \
   fxprintf \
   printf-parsemb \
@@ -211,6 +212,10 @@ tests := \
   xbug \
   # tests
 
+generated += \
+  errlist-data-aux-shared.S \
+  errlist-data-aux.S \
+  # generated
 
 test-srcs = tst-unbputc tst-printf tst-printfsz-islongdouble
 
@@ -246,6 +251,20 @@ tests-special += $(objpfx)tst-errno-manual.out
 
 include ../Rules
 
+# The errlist.c is built in two phases because compiler might reorder the
+# compat_symbol directive prior the object itself and on binutils older
+# than 2.29 it might generate object sizes different than the expected ones.
+$(objpfx)errlist-data-aux-shared.S: errlist-data-gen.c
+	$(make-target-directory)
+	$(compile-command.c) $(pic-cppflags) $(pic-ccflag) $(no-stack-protector) -S
+
+$(objpfx)errlist-data-aux.S: errlist-data-gen.c
+	$(make-target-directory)
+	$(compile-command.c) $(pie-default) $(no-stack-protector) -S
+
+$(objpfx)errlist-data.os: $(objpfx)errlist-data-aux-shared.S
+$(objpfx)errlist-data.o: $(objpfx)errlist-data-aux.S
+
 ifeq ($(run-built-tests),yes)
 LOCALES := \
   de_DE.ISO-8859-1 \
@@ -334,7 +353,6 @@ CFLAGS-isoc99_vfscanf.c += -fexceptions
 CFLAGS-isoc99_vscanf.c += -fexceptions
 CFLAGS-isoc99_fscanf.c += -fexceptions
 CFLAGS-isoc99_scanf.c += -fexceptions
-CFLAGS-errlist.c += $(fno-unit-at-a-time)
 CFLAGS-siglist.c += $(fno-unit-at-a-time)
 
 # scanf14a.c and scanf16a.c test a deprecated extension which is no
diff --git a/stdio-common/err_map.h b/stdio-common/err_map.h
new file mode 100644
index 0000000000..6cc3aa3375
--- /dev/null
+++ b/stdio-common/err_map.h
@@ -0,0 +1,24 @@
+/* Internal errno names mapping definition.
+   Copyright (C) 2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _ERR_MAP_H
+#define _ERR_MAP_H
+
+#define ERR_MAP(n) (n)
+
+#endif
diff --git a/stdio-common/errlist-compat-data.h b/stdio-common/errlist-compat-data.h
new file mode 100644
index 0000000000..7c89c9a5a4
--- /dev/null
+++ b/stdio-common/errlist-compat-data.h
@@ -0,0 +1 @@
+/* Empty  */
diff --git a/stdio-common/errlist-compat.c b/stdio-common/errlist-compat.c
deleted file mode 100644
index 6e25b021ab..0000000000
--- a/stdio-common/errlist-compat.c
+++ /dev/null
@@ -1 +0,0 @@
-/* Empty.  */
diff --git a/stdio-common/errlist-data-gen.c b/stdio-common/errlist-data-gen.c
new file mode 100644
index 0000000000..db4f50e6db
--- /dev/null
+++ b/stdio-common/errlist-data-gen.c
@@ -0,0 +1,34 @@
+/* Internal errno names mapping definition.
+   Copyright (C) 2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <array_length.h>
+#include <err_map.h>
+#include <errno.h>
+#include <libintl.h>
+#include <stdio.h>
+
+const char *const _sys_errlist_internal[] =
+  {
+#define _S(n, str)         [ERR_MAP(n)] = str,
+#include <errlist.h>
+#undef _S
+  };
+const size_t _sys_errlist_internal_len = array_length (_sys_errlist_internal);
+
+/* Include to get the definitions for sys_nerr/_sys_nerr.  */
+#include <errlist-compat-data.h>
diff --git a/stdio-common/errlist-data.S b/stdio-common/errlist-data.S
new file mode 100644
index 0000000000..870b3f40c9
--- /dev/null
+++ b/stdio-common/errlist-data.S
@@ -0,0 +1,7 @@
+#ifdef SHARED
+# include "errlist-data-aux-shared.S"
+#else
+# include "errlist-data-aux.S"
+#endif
+
+#include <errlist-compat-data.h>
diff --git a/stdio-common/errlist.c b/stdio-common/errlist.c
index 1c09a31a7a..4c0a0a218d 100644
--- a/stdio-common/errlist.c
+++ b/stdio-common/errlist.c
@@ -16,29 +16,17 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
-#include <stdio.h>
+#include <array_length.h>
+#include <err_map.h>
 #include <errno.h>
 #include <libintl.h>
-#include <array_length.h>
-
-#ifndef ERR_MAP
-# define ERR_MAP(n) n
-#endif
-
-const char *const _sys_errlist_internal[] =
-  {
-#define _S(n, str)         [ERR_MAP(n)] = str,
-#include <errlist.h>
-#undef _S
-  };
+#include <stdio.h>
 
 const char *
 __get_errlist (int errnum)
 {
   int mapped = ERR_MAP (errnum);
-  if (mapped >= 0 && mapped < array_length (_sys_errlist_internal))
+  if (mapped >= 0 && mapped < _sys_errlist_internal_len)
     return _sys_errlist_internal[mapped];
   return NULL;
 }
-
-#include <errlist-compat.c>