OpenMP: #pragma omp task

omp_task.txt

#include <stdio.h>
#include <stdlib.h>
#include <omp.h>

int main(void)
{
	int s, a = 4, b = 2;

#pragma omp task shared(s)
	s = a + b;

#pragma omp taskwait
	printf("s is %d\n", s);

	return 0;
}

==============================================================================
After OpenMP lowering and expansion:
==============================================================================

/*
 * libgomp/task.c:
 * - GOMP_task
 * - GOMP_taskwait
 */

extern void GOMP_task(void (*fn)(void *), void *data, void (*copyfn)(void *, void *),
        long arg_size, long arg_align, bool if_clause, unsigned flags __attribute__((unused)));
extern void GOMP_taskwait(void);

struct omp_data {
	int a, b, *s;
};

void main_omp_fn_0(struct omp_data *omp_data)
{
	int *s, a, b;
	
	a = omp_data->a;
	b = omp_data->b;
	s = omp_data->s;

	*s = a + b;
}

int main(void)
{
	int s, a = 4, b = 2;
	struct omp_data omp_data;

	omp_data.a = a;
	omp_data.b = b;
	omp_data.s = &s;

	__builtin_GOMP_task(main_omp_fn_0, &omp_data, NULL, 12, 4, 1, 0);

	// Waits until child tasks have completed
	// Helps executing them
	__builtin_GOMP_taskwait();

	printf("s is %d\n", s);
	
	return 0;
}