gh-89640: Hardcode WASM float word ordering as little endian (#126387)

diff --git a/Misc/NEWS.d/next/Build/2024-11-04-09-42-04.gh-issue-89640.QBv05o.rst b/Misc/NEWS.d/next/Build/2024-11-04-09-42-04.gh-issue-89640.QBv05o.rst
new file mode 100644 (file)
index 0000000..4fa44a1
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2024-11-04-09-42-04.gh-issue-89640.QBv05o.rst
@@ -0,0 +1 @@
+Hard-code float word ordering as little endian on WASM.

diff --git a/configure b/configure
index 1097747e05517924737c06c08bdbe3a17950d64c..e529527214da291efd9680e0487a7bd86541bde8 100755 (executable)
--- a/configure
+++ b/configure
@@ -24227,41 +24227,34 @@ printf "%s\n" "$ax_cv_c_float_words_bigendian" >&6; }
 case $ax_cv_c_float_words_bigendian in
   yes)
 
-printf "%s\n" "#define FLOAT_WORDS_BIGENDIAN 1" >>confdefs.h
+printf "%s\n" "#define DOUBLE_IS_BIG_ENDIAN_IEEE754 1" >>confdefs.h
  ;;
   no)
-     ;;
-  *)
-    as_fn_error $? "
-
-Unknown float word ordering. You need to manually preset
-ax_cv_c_float_words_bigendian=no (or yes) according to your system.
-
-    " "$LINENO" 5 ;;
-esac
 
+printf "%s\n" "#define DOUBLE_IS_LITTLE_ENDIAN_IEEE754 1" >>confdefs.h
+ ;;
+  *)
+    case $host_cpu in #(
+  *arm*) :
+    # Some ARM platforms use a mixed-endian representation for
+                     # doubles. While Python doesn't currently have full support
+                     # for these platforms (see e.g., issue 1762561), we can at
+                     # least make sure that float <-> string conversions work.
+                     # FLOAT_WORDS_BIGENDIAN doesn't actually detect this case,
+                     # but if it's not big or little, then it must be this?
 
-if test "$ax_cv_c_float_words_bigendian" = "yes"
-then
-
-printf "%s\n" "#define DOUBLE_IS_BIG_ENDIAN_IEEE754 1" >>confdefs.h
-
-elif test "$ax_cv_c_float_words_bigendian" = "no"
-then
+printf "%s\n" "#define DOUBLE_IS_ARM_MIXED_ENDIAN_IEEE754 1" >>confdefs.h
+ ;; #(
+  wasm*) :
 
 printf "%s\n" "#define DOUBLE_IS_LITTLE_ENDIAN_IEEE754 1" >>confdefs.h
+ ;; #(
+  *) :
+     ;;
+esac ;;
+esac
 
-else
-  # Some ARM platforms use a mixed-endian representation for doubles.
-  # While Python doesn't currently have full support for these platforms
-  # (see e.g., issue 1762561), we can at least make sure that float <-> string
-  # conversions work.
-  # FLOAT_WORDS_BIGENDIAN doesn't actually detect this case, but if it's not big
-  # or little, then it must be this?
-
-printf "%s\n" "#define DOUBLE_IS_ARM_MIXED_ENDIAN_IEEE754 1" >>confdefs.h
 
-fi
 
 # The short float repr introduced in Python 3.1 requires the
 # correctly-rounded string <-> double conversion functions from

diff --git a/configure.ac b/configure.ac
index 6d514705e91ce54ec186a89a060041fa2c7c24b1..bc67a0596ac2b438a69184d65a84570134c30233 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -5946,28 +5946,26 @@ AS_VAR_IF([ac_cv_gcc_asm_for_x64], [yes], [
 # * Check for various properties of floating point *
 # **************************************************
 
-AX_C_FLOAT_WORDS_BIGENDIAN
-if test "$ax_cv_c_float_words_bigendian" = "yes"
-then
-  AC_DEFINE([DOUBLE_IS_BIG_ENDIAN_IEEE754], [1],
-  [Define if C doubles are 64-bit IEEE 754 binary format, stored
-   with the most significant byte first])
-elif test "$ax_cv_c_float_words_bigendian" = "no"
-then
-  AC_DEFINE([DOUBLE_IS_LITTLE_ENDIAN_IEEE754], [1],
-  [Define if C doubles are 64-bit IEEE 754 binary format, stored
-   with the least significant byte first])
-else
-  # Some ARM platforms use a mixed-endian representation for doubles.
-  # While Python doesn't currently have full support for these platforms
-  # (see e.g., issue 1762561), we can at least make sure that float <-> string
-  # conversions work.
-  # FLOAT_WORDS_BIGENDIAN doesn't actually detect this case, but if it's not big
-  # or little, then it must be this?
-  AC_DEFINE([DOUBLE_IS_ARM_MIXED_ENDIAN_IEEE754], [1],
-  [Define if C doubles are 64-bit IEEE 754 binary format, stored
-   in ARM mixed-endian order (byte order 45670123)])
-fi
+AX_C_FLOAT_WORDS_BIGENDIAN(
+  [AC_DEFINE([DOUBLE_IS_BIG_ENDIAN_IEEE754], [1],
+             [Define if C doubles are 64-bit IEEE 754 binary format,
+              stored with the most significant byte first])],
+  [AC_DEFINE([DOUBLE_IS_LITTLE_ENDIAN_IEEE754], [1],
+             [Define if C doubles are 64-bit IEEE 754 binary format,
+              stored with the least significant byte first])],
+  [AS_CASE([$host_cpu],
+           [*arm*], [# Some ARM platforms use a mixed-endian representation for
+                     # doubles. While Python doesn't currently have full support
+                     # for these platforms (see e.g., issue 1762561), we can at
+                     # least make sure that float <-> string conversions work.
+                     # FLOAT_WORDS_BIGENDIAN doesn't actually detect this case,
+                     # but if it's not big or little, then it must be this?
+                     AC_DEFINE([DOUBLE_IS_ARM_MIXED_ENDIAN_IEEE754], [1],
+                               [Define if C doubles are 64-bit IEEE 754 binary format,
+                                stored in ARM mixed-endian order (byte order 45670123)])],
+           [wasm*], [AC_DEFINE([DOUBLE_IS_LITTLE_ENDIAN_IEEE754], [1],
+                               [Define if C doubles are 64-bit IEEE 754 binary format,
+                                stored with the least significant byte first])])])
 
 # The short float repr introduced in Python 3.1 requires the
 # correctly-rounded string <-> double conversion functions from

diff --git a/pyconfig.h.in b/pyconfig.h.in
index fcb8a965b1e4769e9be7a55a7e04ad7db06bf816..924d86627b0e9bac0f9e172f2f5e815144fb90dc 100644 (file)
--- a/pyconfig.h.in
+++ b/pyconfig.h.in
@@ -47,10 +47,6 @@
 /* Define if --enable-ipv6 is specified */
 #undef ENABLE_IPV6
 
-/* Define to 1 if your system stores words within floats with the most
-   significant word first */
-#undef FLOAT_WORDS_BIGENDIAN
-
 /* Define if getpgrp() must be called as getpgrp(0). */
 #undef GETPGRP_HAVE_ARG