bpo-29137: Remove fpectl module (#4789)

This module has never been enabled by default, never worked correctly
on x86-64, and caused ABI problems that caused C extension
compatibility. See bpo-29137 for details/discussion.

1 files changed, 3 insertions, 167 deletions

diff --git a/Include/pyfpe.h b/Include/pyfpe.h
index d86cb74..5a99e39 100644
--- a/Include/pyfpe.h
+++ b/Include/pyfpe.h
@@ -1,176 +1,12 @@
 #ifndef Py_PYFPE_H
 #define Py_PYFPE_H
-#ifdef __cplusplus
-extern "C" {
-#endif
-/*
-     ---------------------------------------------------------------------
-    /                       Copyright (c) 1996.                           \
-   |          The Regents of the University of California.                 |
-   |                        All rights reserved.                           |
-   |                                                                       |
-   |   Permission to use, copy, modify, and distribute this software for   |
-   |   any purpose without fee is hereby granted, provided that this en-   |
-   |   tire notice is included in all copies of any software which is or   |
-   |   includes  a  copy  or  modification  of  this software and in all   |
-   |   copies of the supporting documentation for such software.           |
-   |                                                                       |
-   |   This  work was produced at the University of California, Lawrence   |
-   |   Livermore National Laboratory under  contract  no.  W-7405-ENG-48   |
-   |   between  the  U.S.  Department  of  Energy and The Regents of the   |
-   |   University of California for the operation of UC LLNL.              |
-   |                                                                       |
-   |                              DISCLAIMER                               |
-   |                                                                       |
-   |   This  software was prepared as an account of work sponsored by an   |
-   |   agency of the United States Government. Neither the United States   |
-   |   Government  nor the University of California nor any of their em-   |
-   |   ployees, makes any warranty, express or implied, or  assumes  any   |
-   |   liability  or  responsibility  for the accuracy, completeness, or   |
-   |   usefulness of any information,  apparatus,  product,  or  process   |
-   |   disclosed,   or  represents  that  its  use  would  not  infringe   |
-   |   privately-owned rights. Reference herein to any specific  commer-   |
-   |   cial  products,  process,  or  service  by trade name, trademark,   |
-   |   manufacturer, or otherwise, does not  necessarily  constitute  or   |
-   |   imply  its endorsement, recommendation, or favoring by the United   |
-   |   States Government or the University of California. The views  and   |
-   |   opinions  of authors expressed herein do not necessarily state or   |
-   |   reflect those of the United States Government or  the  University   |
-   |   of  California,  and shall not be used for advertising or product   |
-    \  endorsement purposes.                                              /
-     ---------------------------------------------------------------------
-*/
 
-/*
- *       Define macros for handling SIGFPE.
- *       Lee Busby, LLNL, November, 1996
- *       busby1@llnl.gov
- *
- *********************************************
- * Overview of the system for handling SIGFPE:
- *
- * This file (Include/pyfpe.h) defines a couple of "wrapper" macros for
- * insertion into your Python C code of choice. Their proper use is
- * discussed below. The file Python/pyfpe.c defines a pair of global
- * variables PyFPE_jbuf and PyFPE_counter which are used by the signal
- * handler for SIGFPE to decide if a particular exception was protected
- * by the macros. The signal handler itself, and code for enabling the
- * generation of SIGFPE in the first place, is in a (new) Python module
- * named fpectl. This module is standard in every respect. It can be loaded
- * either statically or dynamically as you choose, and like any other
- * Python module, has no effect until you import it.
- *
- * In the general case, there are three steps toward handling SIGFPE in any
- * Python code:
- *
- * 1) Add the *_PROTECT macros to your C code as required to protect
- *    dangerous floating point sections.
- *
- * 2) Turn on the inclusion of the code by adding the ``--with-fpectl''
- *    flag at the time you run configure.  If the fpectl or other modules
- *    which use the *_PROTECT macros are to be dynamically loaded, be
- *    sure they are compiled with WANT_SIGFPE_HANDLER defined.
- *
- * 3) When python is built and running, import fpectl, and execute
- *    fpectl.turnon_sigfpe(). This sets up the signal handler and enables
- *    generation of SIGFPE whenever an exception occurs. From this point
- *    on, any properly trapped SIGFPE should result in the Python
- *    FloatingPointError exception.
- *
- * Step 1 has been done already for the Python kernel code, and should be
- * done soon for the NumPy array package.  Step 2 is usually done once at
- * python install time. Python's behavior with respect to SIGFPE is not
- * changed unless you also do step 3. Thus you can control this new
- * facility at compile time, or run time, or both.
- *
- ********************************
- * Using the macros in your code:
- *
- * static PyObject *foobar(PyObject *self,PyObject *args)
- * {
- *     ....
- *     PyFPE_START_PROTECT("Error in foobar", return 0)
- *     result = dangerous_op(somearg1, somearg2, ...);
- *     PyFPE_END_PROTECT(result)
- *     ....
- * }
- *
- * If a floating point error occurs in dangerous_op, foobar returns 0 (NULL),
- * after setting the associated value of the FloatingPointError exception to
- * "Error in foobar". ``Dangerous_op'' can be a single operation, or a block
- * of code, function calls, or any combination, so long as no alternate
- * return is possible before the PyFPE_END_PROTECT macro is reached.
- *
- * The macros can only be used in a function context where an error return
- * can be recognized as signaling a Python exception. (Generally, most
- * functions that return a PyObject * will qualify.)
- *
- * Guido's original design suggestion for PyFPE_START_PROTECT and
- * PyFPE_END_PROTECT had them open and close a local block, with a locally
- * defined jmp_buf and jmp_buf pointer. This would allow recursive nesting
- * of the macros. The Ansi C standard makes it clear that such local
- * variables need to be declared with the "volatile" type qualifier to keep
- * setjmp from corrupting their values. Some current implementations seem
- * to be more restrictive. For example, the HPUX man page for setjmp says
- *
- *   Upon the return from a setjmp() call caused by a longjmp(), the
- *   values of any non-static local variables belonging to the routine
- *   from which setjmp() was called are undefined. Code which depends on
- *   such values is not guaranteed to be portable.
- *
- * I therefore decided on a more limited form of nesting, using a counter
- * variable (PyFPE_counter) to keep track of any recursion.  If an exception
- * occurs in an ``inner'' pair of macros, the return will apparently
- * come from the outermost level.
- *
+/* These macros used to do something when Python was built with --with-fpectl,
+ * but support for that was dropped in 3.7. We continue to define them though,
+ * to avoid breaking API users.
  */
 
-#ifdef WANT_SIGFPE_HANDLER
-#include <signal.h>
-#include <setjmp.h>
-#include <math.h>
-extern jmp_buf PyFPE_jbuf;
-extern int PyFPE_counter;
-extern double PyFPE_dummy(void *);
-
-#define PyFPE_START_PROTECT(err_string, leave_stmt) \
-if (!PyFPE_counter++ && setjmp(PyFPE_jbuf)) { \
-        PyErr_SetString(PyExc_FloatingPointError, err_string); \
-        PyFPE_counter = 0; \
-        leave_stmt; \
-}
-
-/*
- * This (following) is a heck of a way to decrement a counter. However,
- * unless the macro argument is provided, code optimizers will sometimes move
- * this statement so that it gets executed *before* the unsafe expression
- * which we're trying to protect.  That pretty well messes things up,
- * of course.
- *
- * If the expression(s) you're trying to protect don't happen to return a
- * value, you will need to manufacture a dummy result just to preserve the
- * correct ordering of statements.  Note that the macro passes the address
- * of its argument (so you need to give it something which is addressable).
- * If your expression returns multiple results, pass the last such result
- * to PyFPE_END_PROTECT.
- *
- * Note that PyFPE_dummy returns a double, which is cast to int.
- * This seeming insanity is to tickle the Floating Point Unit (FPU).
- * If an exception has occurred in a preceding floating point operation,
- * some architectures (notably Intel 80x86) will not deliver the interrupt
- * until the *next* floating point operation.  This is painful if you've
- * already decremented PyFPE_counter.
- */
-#define PyFPE_END_PROTECT(v) PyFPE_counter -= (int)PyFPE_dummy(&(v));
-
-#else
-
 #define PyFPE_START_PROTECT(err_string, leave_stmt)
 #define PyFPE_END_PROTECT(v)
 
-#endif
-
-#ifdef __cplusplus
-}
-#endif
 #endif /* !Py_PYFPE_H */