Performance — libgccjit v6.1.0 ( ) documentation (original) (raw)
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 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 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”:
/* 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.
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
gcc_jit_timer¶
gcc_jit_timer * gcc_jit_timer_new(void)¶
Create a gcc_jit_timer instance, and start timing:
gcc_jit_timer *t = gcc_jit_timer_new ();
This API entrypoint was added in LIBGCCJIT_ABI_4; you can test for its presence using
#ifdef LIBGCCJIT_HAVE_TIMING_API
void gcc_jit_timer_release(gcc_jit_timer *timer)¶
Release a gcc_jit_timer instance:
gcc_jit_timer_release (t);
This should be called exactly once on a timer.
This API entrypoint was added in LIBGCCJIT_ABI_4; you can test for its presence using
#ifdef LIBGCCJIT_HAVE_TIMING_API
void gcc_jit_context_set_timer(gcc_jit_context *ctxt, gcc_jit_timer *timer)¶
Associate a gcc_jit_timer instance with a context:
gcc_jit_context_set_timer (ctxt, t);
A timer instance can be shared between multiplegcc_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 LIBGCCJIT_ABI_4; you can test for its presence using
#ifdef LIBGCCJIT_HAVE_TIMING_API
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 LIBGCCJIT_ABI_4; you can test for its presence using
#ifdef LIBGCCJIT_HAVE_TIMING_API
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 LIBGCCJIT_ABI_4; you can test for its presence using
#ifdef LIBGCCJIT_HAVE_TIMING_API
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 LIBGCCJIT_ABI_4; you can test for its presence using
#ifdef LIBGCCJIT_HAVE_TIMING_API
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 LIBGCCJIT_ABI_4; you can test for its presence using
#ifdef LIBGCCJIT_HAVE_TIMING_API