| .. Copyright (C) 2015-2022 Free Software Foundation, Inc. |
| Originally contributed by David Malcolm <dmalcolm@redhat.com> |
| |
| This is free software: you can redistribute it and/or modify it |
| under the terms of the GNU General Public License as published by |
| the Free Software Foundation, either version 3 of the License, or |
| (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program. If not, see |
| <https://www.gnu.org/licenses/>. |
| |
| .. default-domain:: c |
| |
| Performance |
| =========== |
| |
| The timing API |
| -------------- |
| |
| As of GCC 6, libgccjit exposes a timing API, for printing reports on |
| how long was spent in different parts of code. |
| |
| You can create a :c:type:`gcc_jit_timer` instance, which will |
| measure time spent since its creation. The timer maintains a stack |
| of "timer items": as control flow moves through your code, you can push |
| and pop named items relating to your code onto the stack, and the timer |
| will account the time spent accordingly. |
| |
| You can also asssociate a timer with a :c:type:`gcc_jit_context`, in |
| which case the time spent inside compilation will be subdivided. |
| |
| For example, the following code uses a timer, recording client items |
| "create_code", "compile", and "running code": |
| |
| .. code-block:: c |
| |
| /* Create a timer. */ |
| gcc_jit_timer *timer = gcc_jit_timer_new (); |
| if (!timer) |
| { |
| error ("gcc_jit_timer_new failed"); |
| return -1; |
| } |
| |
| /* Let's repeatedly compile and run some code, accumulating it |
| all into the timer. */ |
| for (int i = 0; i < num_iterations; i++) |
| { |
| /* Create a context and associate it with the timer. */ |
| gcc_jit_context *ctxt = gcc_jit_context_acquire (); |
| if (!ctxt) |
| { |
| error ("gcc_jit_context_acquire failed"); |
| return -1; |
| } |
| gcc_jit_context_set_timer (ctxt, timer); |
| |
| /* Populate the context, timing it as client item "create_code". */ |
| gcc_jit_timer_push (timer, "create_code"); |
| create_code (ctxt); |
| gcc_jit_timer_pop (timer, "create_code"); |
| |
| /* Compile the context, timing it as client item "compile". */ |
| gcc_jit_timer_push (timer, "compile"); |
| result = gcc_jit_context_compile (ctxt); |
| gcc_jit_timer_pop (timer, "compile"); |
| |
| /* Run the generated code, timing it as client item "running code". */ |
| gcc_jit_timer_push (timer, "running code"); |
| run_the_code (ctxt, result); |
| gcc_jit_timer_pop (timer, "running code"); |
| |
| /* Clean up. */ |
| gcc_jit_context_release (ctxt); |
| gcc_jit_result_release (result); |
| } |
| |
| /* Print the accumulated timings. */ |
| gcc_jit_timer_print (timer, stderr); |
| gcc_jit_timer_release (timer); |
| |
| giving output like this, showing the internal GCC items at the top, then |
| client items, then the total:: |
| |
| Execution times (seconds) |
| GCC items: |
| phase setup : 0.29 (14%) usr 0.00 ( 0%) sys 0.32 ( 5%) wall 10661 kB (50%) ggc |
| phase parsing : 0.02 ( 1%) usr 0.00 ( 0%) sys 0.00 ( 0%) wall 653 kB ( 3%) ggc |
| phase finalize : 0.01 ( 1%) usr 0.00 ( 0%) sys 0.00 ( 0%) wall 0 kB ( 0%) ggc |
| dump files : 0.02 ( 1%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall 0 kB ( 0%) ggc |
| callgraph construction : 0.02 ( 1%) usr 0.01 ( 6%) sys 0.01 ( 0%) wall 242 kB ( 1%) ggc |
| callgraph optimization : 0.03 ( 2%) usr 0.00 ( 0%) sys 0.02 ( 0%) wall 142 kB ( 1%) ggc |
| trivially dead code : 0.01 ( 1%) usr 0.00 ( 0%) sys 0.00 ( 0%) wall 0 kB ( 0%) ggc |
| df scan insns : 0.01 ( 1%) usr 0.00 ( 0%) sys 0.00 ( 0%) wall 9 kB ( 0%) ggc |
| df live regs : 0.01 ( 1%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall 0 kB ( 0%) ggc |
| inline parameters : 0.02 ( 1%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall 82 kB ( 0%) ggc |
| tree CFG cleanup : 0.01 ( 1%) usr 0.00 ( 0%) sys 0.00 ( 0%) wall 0 kB ( 0%) ggc |
| tree PHI insertion : 0.01 ( 1%) usr 0.00 ( 0%) sys 0.02 ( 0%) wall 64 kB ( 0%) ggc |
| tree SSA other : 0.01 ( 1%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall 18 kB ( 0%) ggc |
| expand : 0.01 ( 1%) usr 0.00 ( 0%) sys 0.00 ( 0%) wall 398 kB ( 2%) ggc |
| jump : 0.01 ( 1%) usr 0.00 ( 0%) sys 0.00 ( 0%) wall 0 kB ( 0%) ggc |
| loop init : 0.01 ( 0%) usr 0.00 ( 0%) sys 0.00 ( 0%) wall 67 kB ( 0%) ggc |
| integrated RA : 0.02 ( 1%) usr 0.00 ( 0%) sys 0.00 ( 0%) wall 2468 kB (12%) ggc |
| thread pro- & epilogue : 0.01 ( 1%) usr 0.00 ( 0%) sys 0.00 ( 0%) wall 162 kB ( 1%) ggc |
| final : 0.01 ( 1%) usr 0.00 ( 0%) sys 0.00 ( 0%) wall 216 kB ( 1%) ggc |
| rest of compilation : 1.37 (69%) usr 0.00 ( 0%) sys 1.13 (18%) wall 1391 kB ( 6%) ggc |
| assemble JIT code : 0.01 ( 1%) usr 0.00 ( 0%) sys 4.04 (66%) wall 0 kB ( 0%) ggc |
| load JIT result : 0.02 ( 1%) usr 0.00 ( 0%) sys 0.00 ( 0%) wall 0 kB ( 0%) ggc |
| JIT client code : 0.00 ( 0%) usr 0.01 ( 6%) sys 0.00 ( 0%) wall 0 kB ( 0%) ggc |
| Client items: |
| create_code : 0.00 ( 0%) usr 0.01 ( 6%) sys 0.00 ( 0%) wall 0 kB ( 0%) ggc |
| compile : 0.36 (18%) usr 0.15 (83%) sys 0.86 (14%) wall 14939 kB (70%) ggc |
| running code : 0.00 ( 0%) usr 0.00 ( 0%) sys 0.00 ( 0%) wall 0 kB ( 0%) ggc |
| TOTAL : 2.00 0.18 6.12 21444 kB |
| |
| The exact format is intended to be human-readable, and is subject to change. |
| |
| .. macro:: LIBGCCJIT_HAVE_TIMING_API |
| |
| The timer API was added to libgccjit in GCC 6. |
| This macro is only defined in versions of libgccjit.h which have the |
| timer API, and so can be used to guard code that may need to compile |
| against earlier releases:: |
| |
| #ifdef LIBGCCJIT_HAVE_TIMING_API |
| gcc_jit_timer *t = gcc_jit_timer_new (); |
| gcc_jit_context_set_timer (ctxt, t); |
| #endif |
| |
| .. type:: gcc_jit_timer |
| |
| .. function:: gcc_jit_timer * gcc_jit_timer_new(void) |
| |
| Create a :c:type:`gcc_jit_timer` instance, and start timing:: |
| |
| gcc_jit_timer *t = gcc_jit_timer_new (); |
| |
| This API entrypoint was added in :ref:`LIBGCCJIT_ABI_4`; you can test |
| for its presence using |
| |
| .. code-block:: c |
| |
| #ifdef LIBGCCJIT_HAVE_TIMING_API |
| |
| .. function:: void gcc_jit_timer_release(gcc_jit_timer *timer) |
| |
| Release a :c:type:`gcc_jit_timer` instance:: |
| |
| gcc_jit_timer_release (t); |
| |
| This should be called exactly once on a timer. |
| |
| This API entrypoint was added in :ref:`LIBGCCJIT_ABI_4`; you can test |
| for its presence using |
| |
| .. code-block:: c |
| |
| #ifdef LIBGCCJIT_HAVE_TIMING_API |
| |
| .. function:: void gcc_jit_context_set_timer(gcc_jit_context *ctxt, \ |
| gcc_jit_timer *timer) |
| |
| Associate a :c:type:`gcc_jit_timer` instance with a context:: |
| |
| gcc_jit_context_set_timer (ctxt, t); |
| |
| A timer instance can be shared between multiple |
| :c:type:`gcc_jit_context` instances. |
| |
| Timers have no locking, so if you have a multithreaded program, you |
| must provide your own locks if more than one thread could be working |
| with the same timer via timer-associated contexts. |
| |
| This API entrypoint was added in :ref:`LIBGCCJIT_ABI_4`; you can test |
| for its presence using |
| |
| .. code-block:: c |
| |
| #ifdef LIBGCCJIT_HAVE_TIMING_API |
| |
| .. function:: gcc_jit_timer *gcc_jit_context_get_timer(gcc_jit_context *ctxt) |
| |
| Get the timer associated with a context (if any). |
| |
| This API entrypoint was added in :ref:`LIBGCCJIT_ABI_4`; you can test |
| for its presence using |
| |
| .. code-block:: c |
| |
| #ifdef LIBGCCJIT_HAVE_TIMING_API |
| |
| .. function:: void gcc_jit_timer_push(gcc_jit_timer *timer, \ |
| const char *item_name) |
| |
| Push the given item onto the timer's stack:: |
| |
| gcc_jit_timer_push (t, "running code"); |
| run_the_code (ctxt, result); |
| gcc_jit_timer_pop (t, "running code"); |
| |
| This API entrypoint was added in :ref:`LIBGCCJIT_ABI_4`; you can test |
| for its presence using |
| |
| .. code-block:: c |
| |
| #ifdef LIBGCCJIT_HAVE_TIMING_API |
| |
| .. function:: void gcc_jit_timer_pop(gcc_jit_timer *timer, \ |
| const char *item_name) |
| |
| Pop the top item from the timer's stack. |
| |
| If "item_name" is provided, it must match that of the top item. |
| Alternatively, ``NULL`` can be passed in, to suppress checking. |
| |
| This API entrypoint was added in :ref:`LIBGCCJIT_ABI_4`; you can test |
| for its presence using |
| |
| .. code-block:: c |
| |
| #ifdef LIBGCCJIT_HAVE_TIMING_API |
| |
| .. function:: void gcc_jit_timer_print(gcc_jit_timer *timer, \ |
| FILE *f_out) |
| |
| Print timing information to the given stream about activity since |
| the timer was started. |
| |
| This API entrypoint was added in :ref:`LIBGCCJIT_ABI_4`; you can test |
| for its presence using |
| |
| .. code-block:: c |
| |
| #ifdef LIBGCCJIT_HAVE_TIMING_API |
