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/*
Tutorial 3 - compiling on-demand
Builds and compiles the following function:
int mul_add(int x, int y, int z)
{
return x * y + z;
}
Differs from Tutorial 1 in that this version only builds the function
when it is called, not at startup time.
*/
#include <stdio.h>
#include <jit/jit.h>
int compile_mul_add(jit_function_t function)
{
jit_value_t x, y, z;
jit_value_t temp1, temp2;
printf("Compiling mul_add on demand\n");
x = jit_value_get_param(function, 0);
y = jit_value_get_param(function, 1);
z = jit_value_get_param(function, 2);
temp1 = jit_insn_mul(function, x, y);
temp2 = jit_insn_add(function, temp1, z);
jit_insn_return(function, temp2);
return 1;
}
int main(int argc, char **argv)
{
jit_context_t context;
jit_type_t params[3];
jit_type_t signature;
jit_function_t function;
jit_int arg1, arg2, arg3;
void *args[3];
jit_int result;
/* Create a context to hold the JIT's primary state */
context = jit_context_create();
/* Lock the context while we construct the function */
jit_context_build_start(context);
/* Build the function signature */
params[0] = jit_type_int;
params[1] = jit_type_int;
params[2] = jit_type_int;
signature = jit_type_create_signature
(jit_abi_cdecl, jit_type_int, params, 3, 1);
/* Create the function object */
function = jit_function_create(context, signature);
jit_type_free(signature);
/* Make the function recompilable */
jit_function_set_recompilable(function);
/* Set the on-demand compiler for "mul_add" */
jit_function_set_on_demand_compiler(function, compile_mul_add);
/* Unlock the context. It will be automatically locked for
us when the on-demand compiler is called */
jit_context_build_end(context);
/* Execute the function and print the result. This will arrange
to call the on-demand compiler to build the function's body */
arg1 = 3;
arg2 = 5;
arg3 = 2;
args[0] = &arg1;
args[1] = &arg2;
args[2] = &arg3;
jit_function_apply(function, args, &result);
printf("mul_add(3, 5, 2) = %d\n", (int)result);
/* Execute the function again, to demonstrate that the
on-demand compiler is not invoked a second time */
arg1 = 13;
arg2 = 5;
arg3 = 7;
args[0] = &arg1;
args[1] = &arg2;
args[2] = &arg3;
jit_function_apply(function, args, &result);
printf("mul_add(13, 5, 7) = %d\n", (int)result);
/* Force the function to be recompiled. Normally we'd use another
on-demand compiler with greater optimization capabilities */
jit_context_build_start(context);
jit_function_get_on_demand_compiler(function)(function);
jit_function_compile(function);
jit_context_build_end(context);
/* Execute the function a third time, after it is recompiled */
arg1 = 2;
arg2 = 18;
arg3 = -3;
args[0] = &arg1;
args[1] = &arg2;
args[2] = &arg3;
jit_function_apply(function, args, &result);
printf("mul_add(2, 18, -3) = %d\n", (int)result);
/* Clean up */
jit_context_destroy(context);
/* Finished */
return 0;
}