diff options
Diffstat (limited to 'Python')
| -rw-r--r-- | Python/ceval.c | 24 | ||||
| -rw-r--r-- | Python/pythonrun.c | 24 |
2 files changed, 25 insertions, 23 deletions
diff --git a/Python/ceval.c b/Python/ceval.c index ec279bf339..c75caf6823 100644 --- a/Python/ceval.c +++ b/Python/ceval.c @@ -617,18 +617,20 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag) COMPARE_OP is often followed by JUMP_IF_FALSE or JUMP_IF_TRUE. And, those opcodes are often followed by a POP_TOP. - Verifying the prediction costs a single high-speed test of register + Verifying the prediction costs a single high-speed test of a register variable against a constant. If the pairing was good, then the - processor has a high likelihood of making its own successful branch - prediction which results in a nearly zero overhead transition to the - next opcode. - - A successful prediction saves a trip through the eval-loop including - its two unpredictable branches, the HAS_ARG test and the switch-case. - - If collecting opcode statistics, turn off prediction so that - statistics are accurately maintained (the predictions bypass - the opcode frequency counter updates). + processor's own internal branch predication has a high likelihood of + success, resulting in a nearly zero-overhead transition to the + next opcode. A successful prediction saves a trip through the eval-loop + including its two unpredictable branches, the HAS_ARG test and the + switch-case. Combined with the processor's internal branch prediction, + a successful PREDICT has the effect of making the two opcodes run as if + they were a single new opcode with the bodies combined. + + If collecting opcode statistics, your choices are to either keep the + predictions turned-on and interpret the results as if some opcodes + had been combined or turn-off predictions so that the opcode frequency + counter updates for both opcodes. */ #ifdef DYNAMIC_EXECUTION_PROFILE diff --git a/Python/pythonrun.c b/Python/pythonrun.c index d13563ffb3..3a6cc9120c 100644 --- a/Python/pythonrun.c +++ b/Python/pythonrun.c @@ -229,14 +229,14 @@ Py_InitializeEx(int install_sigs) if (install_sigs) initsigs(); /* Signal handling stuff, including initintr() */ - /* Initialize warnings. */ - _PyWarnings_Init(); - if (PySys_HasWarnOptions()) { - PyObject *warnings_module = PyImport_ImportModule("warnings"); - if (!warnings_module) - PyErr_Clear(); - Py_XDECREF(warnings_module); - } + /* Initialize warnings. */ + _PyWarnings_Init(); + if (PySys_HasWarnOptions()) { + PyObject *warnings_module = PyImport_ImportModule("warnings"); + if (!warnings_module) + PyErr_Clear(); + Py_XDECREF(warnings_module); + } initmain(); /* Module __main__ */ if (!Py_NoSiteFlag) @@ -1246,7 +1246,7 @@ PyErr_PrintEx(int set_sys_last_vars) PyException_SetTraceback(v, tb); if (exception == NULL) return; - /* Now we know v != NULL too */ + /* Now we know v != NULL too */ if (set_sys_last_vars) { PySys_SetObject("last_type", exception); PySys_SetObject("last_value", v); @@ -2096,14 +2096,14 @@ PyRun_AnyFileFlags(FILE *fp, const char *name, PyCompilerFlags *flags) PyAPI_FUNC(PyObject *) PyRun_File(FILE *fp, const char *p, int s, PyObject *g, PyObject *l) { - return PyRun_FileExFlags(fp, p, s, g, l, 0, NULL); + return PyRun_FileExFlags(fp, p, s, g, l, 0, NULL); } #undef PyRun_FileEx PyAPI_FUNC(PyObject *) PyRun_FileEx(FILE *fp, const char *p, int s, PyObject *g, PyObject *l, int c) { - return PyRun_FileExFlags(fp, p, s, g, l, c, NULL); + return PyRun_FileExFlags(fp, p, s, g, l, c, NULL); } #undef PyRun_FileFlags @@ -2111,7 +2111,7 @@ PyAPI_FUNC(PyObject *) PyRun_FileFlags(FILE *fp, const char *p, int s, PyObject *g, PyObject *l, PyCompilerFlags *flags) { - return PyRun_FileExFlags(fp, p, s, g, l, 0, flags); + return PyRun_FileExFlags(fp, p, s, g, l, 0, flags); } #undef PyRun_SimpleFile |