[PATCH] Added Redirects to longdouble error functions [BZ #29033]

[Sachin Monga <smonga@linux.ibm.com>]

This patch redirects the error functions to the appropriate
longdouble variants which enables the compiler to optimize
for the abi ieeelongdouble.

Signed-off-by: Sachin Monga <smonga@linux.ibm.com>
---
 misc/Makefile                               |  2 +-
 misc/bits/error-ldbl.h                      | 45 +++++++++++
 misc/sys/cdefs.h                            |  3 +-
 misc/tst-ldbl-errorfptr.c                   | 87 +++++++++++++++++++++
 sysdeps/ieee754/ldbl-128ibm-compat/Makefile |  2 +
 sysdeps/ieee754/ldbl-opt/Makefile           |  4 +
 6 files changed, 141 insertions(+), 2 deletions(-)
 create mode 100644 misc/tst-ldbl-errorfptr.c

diff --git a/misc/Makefile b/misc/Makefile
index 1a09f777fa..9f42321206 100644
--- a/misc/Makefile
+++ b/misc/Makefile
@@ -90,7 +90,7 @@ tests := tst-dirname tst-tsearch tst-fdset tst-mntent tst-hsearch \
 	 tst-preadvwritev2 tst-preadvwritev64v2 tst-warn-wide \
 	 tst-ldbl-warn tst-ldbl-error tst-dbl-efgcvt tst-ldbl-efgcvt \
 	 tst-mntent-autofs tst-syscalls tst-mntent-escape tst-select \
-	 tst-ioctl
+	 tst-ioctl tst-ldbl-errorfptr
 
 tests-time64 := \
   tst-select-time64 \
diff --git a/misc/bits/error-ldbl.h b/misc/bits/error-ldbl.h
index 599a7d6e06..bbc4956f68 100644
--- a/misc/bits/error-ldbl.h
+++ b/misc/bits/error-ldbl.h
@@ -20,5 +20,50 @@
 # error "Never include <bits/error-ldbl.h> directly; use <error.h> instead."
 #endif
 
+#if defined __extern_always_inline && defined __va_arg_pack
+extern void __REDIRECT_LDBL (__error_alias, (int __status, int __errnum,
+			     const char *__format, ...), error)
+  __attribute__ ((__format__ (__printf__, 3, 4)));
+extern void __REDIRECT_LDBL (__error_noreturn, (int __status, int __errnum,
+			     const char *__format, ...), error)
+  __attribute__ ((__noreturn__, __format__ (__printf__, 3, 4)));
+
+
+/* If we know the function will never return make sure the compiler
+   realizes that, too.  */
+__extern_always_inline void
+error (int __status, int __errnum, const char *__format, ...)
+{
+  if (__builtin_constant_p (__status) && __status != 0)
+    __error_noreturn (__status, __errnum, __format, __va_arg_pack ());
+  else
+    __error_alias (__status, __errnum, __format, __va_arg_pack ());
+}
+
+
+extern void __REDIRECT_LDBL (__error_at_line_alias, (int __status, int __errnum,
+			     const char *__fname, unsigned int __line,
+			     const char *__format, ...), error_at_line)
+  __attribute__ ((__format__ (__printf__, 5, 6)));
+extern void __REDIRECT_LDBL (__error_at_line_noreturn, (int __status, int __errnum,
+			     const char *__fname, unsigned int __line,
+			     const char *__format, ...), error_at_line)
+  __attribute__ ((__noreturn__, __format__ (__printf__, 5, 6)));
+
+
+/* If we know the function will never return make sure the compiler
+   realizes that, too.  */
+__extern_always_inline void
+error_at_line (int __status, int __errnum, const char *__fname,
+	       unsigned int __line, const char *__format, ...)
+{
+  if (__builtin_constant_p (__status) && __status != 0)
+    __error_at_line_noreturn (__status, __errnum, __fname, __line, __format,
+			      __va_arg_pack ());
+  else
+    __error_at_line_alias (__status, __errnum, __fname, __line,
+			   __format, __va_arg_pack ());
+}
+#endif
 __LDBL_REDIR_DECL (error)
 __LDBL_REDIR_DECL (error_at_line)
diff --git a/misc/sys/cdefs.h b/misc/sys/cdefs.h
index 23ec0ebd2a..285191482a 100644
--- a/misc/sys/cdefs.h
+++ b/misc/sys/cdefs.h
@@ -569,6 +569,8 @@
 #  define __LDBL_REDIR(name, proto) ... unused__ldbl_redir
 #  define __LDBL_REDIR_DECL(name) \
   extern __typeof (name) name __asm (__ASMNAME ("__" #name "ieee128"));
+#  define __REDIRECT_LDBL(name, proto, alias) \
+  name proto __asm (__ASMNAME ("__" #alias "ieee128"))
 
 /* Alias name defined automatically, with leading underscores.  */
 #  define __LDBL_REDIR2_DECL(name) \
@@ -586,7 +588,6 @@
   __LDBL_REDIR1_NTH (name, proto, __##alias##ieee128)
 
 /* Unused.  */
-#  define __REDIRECT_LDBL(name, proto, alias) ... unused__redirect_ldbl
 #  define __LDBL_REDIR_NTH(name, proto) ... unused__ldbl_redir_nth
 
 # else
diff --git a/misc/tst-ldbl-errorfptr.c b/misc/tst-ldbl-errorfptr.c
new file mode 100644
index 0000000000..155932afe1
--- /dev/null
+++ b/misc/tst-ldbl-errorfptr.c
@@ -0,0 +1,87 @@
+/* Test for the long double redirections in error* functions
+   when they are returned as function pointer BZ #29033.
+   Copyright (C) 2023 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 <err.h>
+#include <errno.h>
+#include <error.h>
+#include <stdarg.h>
+#include <string.h>
+#include <stdlib.h>
+#include <dlfcn.h>
+#include <sys/cdefs.h>
+
+#include <support/capture_subprocess.h>
+#include <support/check.h>
+#include <support/xdlfcn.h>
+
+#if __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI == 1
+# define LDBL_NAME(alias) "__" #alias "ieee128"
+#elif defined __LONG_DOUBLE_MATH_OPTIONAL && defined __NO_LONG_DOUBLE_MATH
+# define LDBL_NAME(alias) "__nldbl_" #alias
+#else
+# define LDBL_NAME(alias) #alias
+#endif
+
+typedef void (*error_func_t) (int, int, const char*, ...);
+typedef void (*error_at_line_func_t) (int, int, const char*,
+	      unsigned int, const char*, ...);
+
+error_func_t
+__attribute__ ((noinline))
+get_error_func (void) {
+  return &error;
+}
+
+error_at_line_func_t
+__attribute__ ((noinline))
+get_error_at_line_func (void) {
+  return &error_at_line;
+}
+
+static int
+do_test (void)
+{
+  /* Prepare the symbol names as per long double standards */
+  char *error_sym = NULL;
+  char *error_sym_at_line = NULL;
+  error_sym = (char *) LDBL_NAME(error);
+  error_sym_at_line = (char *) LDBL_NAME(error_at_line);
+  TEST_VERIFY (error_sym != NULL && error_sym_at_line != NULL);
+  /* Map the function pointers to appropriate redirected error symbols */
+  error_func_t fp;
+  fp = get_error_func ();
+  if (fp != xdlsym (RTLD_DEFAULT, error_sym))
+    {
+      printf ("FAIL: fp=%p error_sym=%p\n", fp, error_sym);
+      return 1;
+    }
+
+  error_at_line_func_t fpat;
+  fpat = get_error_at_line_func ();
+  if (fpat != xdlsym (RTLD_DEFAULT, error_sym_at_line))
+    {
+      printf ("FAIL: fpat=%p error_sym_at_line=%p\n",
+	      fpat, error_sym_at_line);
+      return 1;
+    }
+
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/sysdeps/ieee754/ldbl-128ibm-compat/Makefile b/sysdeps/ieee754/ldbl-128ibm-compat/Makefile
index d4ec41bf99..42cca25a09 100644
--- a/sysdeps/ieee754/ldbl-128ibm-compat/Makefile
+++ b/sysdeps/ieee754/ldbl-128ibm-compat/Makefile
@@ -264,6 +264,7 @@ CFLAGS-ieee128-qefgcvt_r.c += -mabi=ieeelongdouble -Wno-psabi -mno-gnu-attribute
 tests-internal += tst-ibm128-warn tst-ieee128-warn
 tests-internal += tst-ibm128-error tst-ieee128-error
 tests-internal += tst-ibm128-efgcvt tst-ieee128-efgcvt
+tests-internal += tst-ieee128-errorfptr
 
 $(objpfx)tst-ibm128-%.c: tst-ldbl-%.c
 	cp $< $@
@@ -278,6 +279,7 @@ CFLAGS-tst-ibm128-efgcvt.c += -mabi=ibmlongdouble -Wno-psabi
 CFLAGS-tst-ieee128-warn.c += -mfloat128 -mabi=ieeelongdouble -Wno-psabi
 CFLAGS-tst-ieee128-error.c += -mfloat128 -mabi=ieeelongdouble -Wno-psabi
 CFLAGS-tst-ieee128-efgcvt.c += -mfloat128 -mabi=ieeelongdouble -Wno-psabi
+CFLAGS-tst-ieee128-errorfptr.c += -mfloat128 -mabi=ieeelongdouble -Wno-psabi
 
 tests-container += test-syslog-ieee128 test-syslog-ibm128
 CFLAGS-test-syslog-ieee128.c += -mfloat128 -mabi=ieeelongdouble -Wno-psabi
diff --git a/sysdeps/ieee754/ldbl-opt/Makefile b/sysdeps/ieee754/ldbl-opt/Makefile
index 5b72474aa4..22e778ad0e 100644
--- a/sysdeps/ieee754/ldbl-opt/Makefile
+++ b/sysdeps/ieee754/ldbl-opt/Makefile
@@ -215,6 +215,7 @@ endif
 ifeq ($(subdir), misc)
 tests-internal += tst-nldbl-warn
 tests-internal += tst-nldbl-error
+tests-internal += tst-nldbl-errorfptr
 
 $(objpfx)tst-nldbl-warn.c: tst-ldbl-warn.c
 	cp $< $@
@@ -222,8 +223,11 @@ $(objpfx)tst-nldbl-warn.c: tst-ldbl-warn.c
 $(objpfx)tst-nldbl-error.c: tst-ldbl-error.c
 	cp $< $@
 
+$(objpfx)tst-nldbl-errorfptr.c: tst-ldbl-errorfptr.c
+	cp $< $@
 CFLAGS-tst-nldbl-warn.c += -mlong-double-64
 CFLAGS-tst-nldbl-error.c += -mlong-double-64
+CFLAGS-tst-nldbl-errorfptr.c += -mlong-double-64
 endif
 
 ifeq ($(subdir), stdio-common)
-- 
2.37.2