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bpo-29137: Remove fpectl module (python#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.
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| Original file line number | Diff line number | Diff line change |
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@@ -24,4 +24,3 @@ overview: | |
| gc.rst | ||
| inspect.rst | ||
| site.rst | ||
| fpectl.rst | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -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 */ |
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Misc/NEWS.d/next/Library/2017-12-10-21-19-14.bpo-29137.CFcON1.rst
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,3 @@ | ||
| The ``fpectl`` library has been removed. It was never enabled by default, | ||
| never worked correctly on x86-64, and it changed the Python ABI in ways that | ||
| caused unexpected breakage of C extensions. |
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