[v2,3/4] stdlib: Remove if inline asm context casts if compiler does not support it

diff --git a/Makerules b/Makerules
index 09c0cf8357..1ca16bf080 100644
--- a/Makerules
+++ b/Makerules
@@ -351,6 +351,19 @@  $(common-objpfx)$(lib-names-stmp-abi): $(..)scripts/lib-names.awk \
 endif
 common-generated += $(lib-names-h-abi) $(lib-names-stmp-abi)
 endif
+
+# The inline asm constraints lvalue casts on longlong.h are not fully
+# supported on all compilers.  However, the cast acts as a limited form of
+# typechecking where if the cast can be removed, then the output operand
+# had a type of the proper width, otherwise compiler issue an error.
+# For the case compiler does not fully support the script tries to remove
+# it.
+before-compile += $(common-objpfx)stdlib/longlong.h
+$(common-objpfx)stdlib/longlong.h: $(..)stdlib/longlong.h.in $(..)scripts/filter-asm-inline-cast.py
+	$(make-target-directory)
+	$(PYTHON) $(..)scripts/filter-asm-inline-cast.py --filter $(config-remove-cast-inline-asm) $< $@.tmp
+	mv -f $@.tmp $@
+common-generated += $(common-objpfx)stdlib/longlong.h
 
 ###############################################################################
 # NOTE!  Everything adding to before-compile needs to come before this point! #
diff --git a/configure b/configure
index e23ea95a49..045a51cfba 100755
--- a/configure
+++ b/configure
@@ -6376,6 +6376,35 @@  $as_echo "$libc_cv_wno_ignored_attributes" >&6; }
 config_vars="$config_vars
 config-cflags-wno-ignored-attributes = $libc_cv_wno_ignored_attributes"
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking if cast in inline asm context is supported" >&5
+$as_echo_n "checking if cast in inline asm context is supported... " >&6; }
+if ${libc_cv_cast_inline_asm_context+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat > conftest.c <<EOF
+void foo (void)
+{
+  int i;
+  __asm ("" : "=r" ((unsigned int) i));
+}
+EOF
+libc_cv_remove_cast_inline_asm=no
+if ! { ac_try='${CC-cc} $CFLAGS $CPPFLAGS -Werror -c conftest.c'
+  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; }
+then
+  libc_cv_remove_cast_inline_asm=yes
+fi
+rm -f conftest.*
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_cast_inline_asm_context" >&5
+$as_echo "$libc_cv_cast_inline_asm_context" >&6; }
+config_vars="$config_vars
+config-remove-cast-inline-asm = $libc_cv_remove_cast_inline_asm"
+
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether cc puts quotes around section names" >&5
 $as_echo_n "checking whether cc puts quotes around section names... " >&6; }
 if ${libc_cv_have_section_quotes+:} false; then :
diff --git a/configure.ac b/configure.ac
index 7275b53345..238a7267ef 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1426,6 +1426,28 @@  rm -f conftest*])
 LIBC_CONFIG_VAR([config-cflags-wno-ignored-attributes],
 		[$libc_cv_wno_ignored_attributes])
 
+dnl clang emits and error for cast usage in inline asm context and although
+dnl -fheinous-gnu-extensions option allows to just instruct it to emit an
+dnl warning, clang also explicit warns that the option might be removed in
+dnl the future.
+AC_CACHE_CHECK([if cast in inline asm context is supported],
+	       libc_cv_cast_inline_asm_context, [dnl
+cat > conftest.c <<EOF
+void foo (void)
+{
+  int i;
+  __asm ("" : "=r" ((unsigned int) i));
+}
+EOF
+libc_cv_remove_cast_inline_asm=no
+if ! AC_TRY_COMMAND([${CC-cc} $CFLAGS $CPPFLAGS -Werror -c conftest.c])
+then
+  libc_cv_remove_cast_inline_asm=yes
+fi
+rm -f conftest.*])
+LIBC_CONFIG_VAR([config-remove-cast-inline-asm],
+		[$libc_cv_remove_cast_inline_asm])
+
 AC_CACHE_CHECK(whether cc puts quotes around section names,
 	       libc_cv_have_section_quotes,
 	       [cat > conftest.c <<EOF
diff --git a/scripts/filter-asm-inline-cast.py b/scripts/filter-asm-inline-cast.py
new file mode 100755
index 0000000000..319751e7f2
--- /dev/null
+++ b/scripts/filter-asm-inline-cast.py
@@ -0,0 +1,102 @@ 
+#!/usr/bin/python3
+# Filter out inline asm casts.
+# Copyright (C) 2018-2022 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/>.
+
+import argparse
+import sys
+import re
+
+# Each asm constraint where the cast occurs.
+CONSTRAINT_LIST=(
+    '\"%0\"',
+    '\"%1\"',
+    '\"%dI\"'
+    '\"%rJ\"',
+    '\"%r\"',
+    '\"0\"',
+    '\"1\"',
+    '\"=&g\"',
+    '\"=&r\"',
+    '\"=a\"',
+    '\"=d\"',
+    '\"=g\"',
+    '\"=r\"',
+    '\"dI\"',
+    '\"g\"',
+    '\"rICal\"',
+    '\"rI\"',
+    '\"rJ\"',
+    '\"%rJ\"',
+    '\"rM\"',
+    '\"rQR\"',
+    '\"r\"',
+    '\"rm\"',
+    '\"rme\"',
+    '\"x\"',
+    '\"d\"',
+    '\"=&d\"',
+    '\"dmi\"',
+    '\"%rM\"',
+)
+
+# The cast type used in lvalue asm contraint input.
+REPLACE_CASTS = (
+    "(UDItype)",
+    "(USItype)",
+    "(unsigned int)",
+)
+
+def multireplace(string, repl):
+    if not repl:
+        return string
+
+    # Place longer string first, to avoid shorter substring to match first.
+    rep_sorted = sorted(repl, key=len, reverse=True)
+    rep_escaped = map(re.escape, rep_sorted)
+    pattern = re.compile("|".join(rep_escaped), 0)
+
+    return pattern.sub(lambda match: "", string)
+
+
+def get_parser():
+    def strbool(string):
+        return True if string.lower() == 'yes' else False
+
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument('--filter', dest='filter',
+                        help='Filter out inoine asm casts',
+                        type=strbool)
+    parser.add_argument('input', help='Input file')
+    parser.add_argument('output', help='Ouput file')
+    return parser
+
+
+def main(argv):
+    """The main entry point."""
+    parser = get_parser()
+    opts = parser.parse_args(argv)
+    with open(opts.input, 'r') as i_file, open(opts.output, 'w') as o_file:
+        for line in i_file:
+            replace = REPLACE_CASTS \
+                if opts.filter and any(substring in line for substring in CONSTRAINT_LIST) \
+                else None
+            o_file.write(multireplace(line, replace))
+
+
+if __name__ == '__main__':
+    main(sys.argv[1:])
diff --git a/stdlib/longlong.h b/stdlib/longlong.h.in
similarity index 100%
rename from stdlib/longlong.h
rename to stdlib/longlong.h.in
diff --git a/stdlib/strtod_l.c b/stdlib/strtod_l.c
index 3ebb491e22..fe59907cb2 100644
--- a/stdlib/strtod_l.c
+++ b/stdlib/strtod_l.c
@@ -81,7 +81,7 @@  extern double ____strtod_l_internal (const char *, char **, int, locale_t);
 #include <gmp-mparam.h>
 #include <gmp.h>
 #include "gmp-impl.h"
-#include "longlong.h"
+#include <stdlib/longlong.h>
 #include "fpioconst.h"
 
 #include <assert.h>