autoconf-archive: fix ax_c_float_words_bigendian fails when lto enabled (#12227)

See 23be7ccd7f

tools/autoconf-archive/patches/001-fix_ax_c_float_words_bigendian.patch

@@ -0,0 +1,90 @@
+--- a/m4/ax_c_float_words_bigendian.m4
++++ b/m4/ax_c_float_words_bigendian.m4
+@@ -27,32 +27,81 @@
+ #   If neither value is found, the user is instructed to specify the
+ #   ordering.
+ #
++#   Early versions of this macro (i.e., before serial 12) would not work
++#   when interprocedural optimization (via link-time optimization) was
++#   enabled. This would happen when, say, the GCC/clang "-flto" flag, or the
++#   ICC "-ipo" flag was used, for example. The problem was that under these
++#   conditions, the compiler did not allocate for and write the special
++#   float value in the data segment of the object file, since doing so might
++#   not prove optimal once more context was available. Thus, the special
++#   value (in platform-dependent binary form) could not be found in the
++#   object file, and the macro would fail.
++#
++#   The solution to the above problem was to:
++#
++#     1) Compile and link a whole test program rather than just compile an
++#        object file. This ensures that we reach the point where even an
++#        interprocedural optimizing compiler writes values to the data segment.
++#
++#     2) Add code that requires the compiler to write the special value to
++#        the data segment, as opposed to "optimizing away" the variable's
++#        allocation. This could be done via compiler keywords or options, but
++#        it's tricky to make this work for all versions of all compilers with
++#        all optimization settings. The chosen solution was to make the exit
++#        code of the test program depend on the storing of the special value
++#        in memory (in the data segment). Because the exit code can be
++#        verified, any compiler that aspires to be correct will produce a
++#        program binary that contains the value, which the macro can then find.
++#
++#   How does the exit code depend on the special value residing in memory?
++#   Memory, unlike variables and registers, can be addressed indirectly at
++#   run time. The exit code of this test program is a result of indirectly
++#   reading and writing to the memory region where the special value is
++#   supposed to reside. The actual memory addresses used and the values to
++#   be written are derived from the the program input ("argv") and are
++#   therefore not known at compile or link time. The compiler has no choice
++#   but to defer the computation to run time, and to prepare by allocating
++#   and populating the data segment with the special value. For further
++#   details, refer to the source code of the test program.
++#
++#   Note that the test program is never meant to be run. It only exists to
++#   host a double float value in a given platform's binary format. Thus,
++#   error handling is not included.
++#
+ # LICENSE
+ #
+-#   Copyright (c) 2008 Daniel Amelang <dan@amelang.net>
++#   Copyright (c) 2008, 2023 Daniel Amelang <dan@amelang.net>
+ #
+ #   Copying and distribution of this file, with or without modification, are
+ #   permitted in any medium without royalty provided the copyright notice
+ #   and this notice are preserved. This file is offered as-is, without any
+ #   warranty.
+ 
+-#serial 11
++#serial 13
+ 
+ AC_DEFUN([AX_C_FLOAT_WORDS_BIGENDIAN],
+   [AC_CACHE_CHECK(whether float word ordering is bigendian,
+                   ax_cv_c_float_words_bigendian, [
+ 
+ ax_cv_c_float_words_bigendian=unknown
+-AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
++AC_LINK_IFELSE([AC_LANG_SOURCE([[
++
++#include <stdlib.h>
++
++static double m[] = {9.090423496703681e+223, 0.0};
+ 
+-double d = 90904234967036810337470478905505011476211692735615632014797120844053488865816695273723469097858056257517020191247487429516932130503560650002327564517570778480236724525140520121371739201496540132640109977779420565776568942592.0;
++int main (int argc, char *argv[])
++{
++    m[atoi (argv[1])] += atof (argv[2]);
++    return m[atoi (argv[3])] > 0.0;
++}
+ 
+ ]])], [
+ 
+-if grep noonsees conftest.$ac_objext >/dev/null ; then
++if grep noonsees conftest$EXEEXT >/dev/null ; then
+   ax_cv_c_float_words_bigendian=yes
+ fi
+-if grep seesnoon conftest.$ac_objext >/dev/null ; then
++if grep seesnoon conftest$EXEEXT >/dev/null ; then
+   if test "$ax_cv_c_float_words_bigendian" = unknown; then
+     ax_cv_c_float_words_bigendian=no
+   else