gh-145633: drop runtime checks for floatting-point format in the array module

Author: skirpichev

Modules/arraymodule.c

@@ -11,6 +11,7 @@
 #include "pycore_bytesobject.h"   // _PyBytes_Repeat
 #include "pycore_call.h"          // _PyObject_CallMethod()
 #include "pycore_ceval.h"         // _PyEval_GetBuiltin()
+#include "pycore_floatobject.h"   // _PY_FLOAT_BIG_ENDIAN
 #include "pycore_modsupport.h"    // _PyArg_NoKeywords()
 #include "pycore_moduleobject.h"  // _PyModule_GetState()
 #include "pycore_weakref.h"       // FT_CLEAR_WEAKREFS()
@@ -91,9 +92,6 @@ enum machine_format_code {
      * instead of using the memory content of the array directly. In that
      * case, the array_reconstructor mechanism is bypassed completely, and
      * the standard array constructor is used instead.
-     *
-     * This is will most likely occur when the machine doesn't use IEEE
-     * floating-point numbers.
      */
 
     UNSIGNED_INT8 = 0,
@@ -2011,24 +2009,10 @@ typecode_to_mformat_code(char typecode)
         return UTF32_LE + is_big_endian;
 
     case 'f':
-        if (sizeof(float) == 4) {
-            const float y = 16711938.0;
-            if (memcmp(&y, "\x4b\x7f\x01\x02", 4) == 0)
-                return IEEE_754_FLOAT_BE;
-            if (memcmp(&y, "\x02\x01\x7f\x4b", 4) == 0)
-                return IEEE_754_FLOAT_LE;
-        }
-        return UNKNOWN_FORMAT;
+        return _PY_FLOAT_BIG_ENDIAN ? IEEE_754_FLOAT_BE : IEEE_754_FLOAT_LE;
 
     case 'd':
-        if (sizeof(double) == 8) {
-            const double x = 9006104071832581.0;
-            if (memcmp(&x, "\x43\x3f\xff\x01\x02\x03\x04\x05", 8) == 0)
-                return IEEE_754_DOUBLE_BE;
-            if (memcmp(&x, "\x05\x04\x03\x02\x01\xff\x3f\x43", 8) == 0)
-                return IEEE_754_DOUBLE_LE;
-        }
-        return UNKNOWN_FORMAT;
+        return _PY_FLOAT_BIG_ENDIAN ? IEEE_754_DOUBLE_BE : IEEE_754_DOUBLE_LE;
 
     /* Integers */
     case 'h':