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Port AC_C_BIGENDIAN to cross gcc -std=c11 -flto

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* lib/autoconf/c.m4 (AC_C_BIGENDIAN): Improve the
inherently-unportable grep trick well enough to survive gcc
-std=c11 -flto when cross-compiling (sr#110687).
This commit is contained in:
Paul Eggert 2022-07-27 08:53:35 -07:00
parent e50a50c4dc
commit 234fc6c866
1 changed files with 14 additions and 7 deletions
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21
lib/autoconf/c.m4
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@ -1838,8 +1838,8 @@ AC_DEFUN([AC_C_BIGENDIAN],
[ac_cv_c_bigendian=no],
[ac_cv_c_bigendian=yes],
[# Try to guess by grepping values from an object file.
AC_COMPILE_IFELSE(
[AC_LANG_PROGRAM(
AC_LINK_IFELSE(
[AC_LANG_SOURCE(
[[unsigned short int ascii_mm[] =
{ 0x4249, 0x4765, 0x6E44, 0x6961, 0x6E53, 0x7953, 0 };
unsigned short int ascii_ii[] =
@ -1854,13 +1854,20 @@ AC_DEFUN([AC_C_BIGENDIAN],
int use_ebcdic (int i) {
return ebcdic_mm[i] + ebcdic_ii[i];
}
extern int foo;
]],
[[return use_ascii (foo) == use_ebcdic (foo);]])],
[if grep BIGenDianSyS conftest.$ac_objext >/dev/null; then
int
main (int argc, char **argv)
{
/* Intimidate the compiler so that it does not
optimize the arrays away. */
char *p = argv[0];
ascii_mm[1] = *p++; ebcdic_mm[1] = *p++;
ascii_ii[1] = *p++; ebcdic_ii[1] = *p++;
return use_ascii (argc) == use_ebcdic (*p);
}]])],
[if grep BIGenDianSyS conftest$ac_exeext >/dev/null; then
ac_cv_c_bigendian=yes
fi
if grep LiTTleEnDian conftest.$ac_objext >/dev/null ; then
if grep LiTTleEnDian conftest$ac_exeext >/dev/null ; then
if test "$ac_cv_c_bigendian" = unknown; then
ac_cv_c_bigendian=no
else