gcc/jit/docs/examples/tut03-sum-of-squares.c

   1 /* Usage example for libgccjit.so
   2    Copyright (C) 2014-2015 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it
   7 under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 3, or (at your option)
   9 any later version.
  10
  11 GCC is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING3.  If not see
  18 <http://www.gnu.org/licenses/>.  */
  19
  20 #include <libgccjit.h>
  21
  22 #include <stdlib.h>
  23 #include <stdio.h>
  24
  25 void
  26 create_code (gcc_jit_context *ctxt)
  27 {
  28   /*
  29     Simple sum-of-squares, to test conditionals and looping
  30
  31     int loop_test (int n)
  32     {
  33       int i;
  34       int sum = 0;
  35       for (i = 0; i < n ; i ++)
  36       {
  37         sum += i * i;
  38       }
  39       return sum;
  40    */
  41   gcc_jit_type *the_type =
  42     gcc_jit_context_get_type (ctxt, GCC_JIT_TYPE_INT);
  43   gcc_jit_type *return_type = the_type;
  44
  45   gcc_jit_param *n =
  46     gcc_jit_context_new_param (ctxt, NULL, the_type, "n");
  47   gcc_jit_param *params[1] = {n};
  48   gcc_jit_function *func =
  49     gcc_jit_context_new_function (ctxt, NULL,
  50                                   GCC_JIT_FUNCTION_EXPORTED,
  51                                   return_type,
  52                                   "loop_test",
  53                                   1, params, 0);
  54
  55   /* Build locals:  */
  56   gcc_jit_lvalue *i =
  57     gcc_jit_function_new_local (func, NULL, the_type, "i");
  58   gcc_jit_lvalue *sum =
  59     gcc_jit_function_new_local (func, NULL, the_type, "sum");
  60
  61   gcc_jit_block *b_initial =
  62     gcc_jit_function_new_block (func, "initial");
  63   gcc_jit_block *b_loop_cond =
  64     gcc_jit_function_new_block (func, "loop_cond");
  65   gcc_jit_block *b_loop_body =
  66     gcc_jit_function_new_block (func, "loop_body");
  67   gcc_jit_block *b_after_loop =
  68     gcc_jit_function_new_block (func, "after_loop");
  69
  70   /* sum = 0; */
  71   gcc_jit_block_add_assignment (
  72     b_initial, NULL,
  73     sum,
  74     gcc_jit_context_zero (ctxt, the_type));
  75
  76   /* i = 0; */
  77   gcc_jit_block_add_assignment (
  78     b_initial, NULL,
  79     i,
  80     gcc_jit_context_zero (ctxt, the_type));
  81
  82   gcc_jit_block_end_with_jump (b_initial, NULL, b_loop_cond);
  83
  84   /* if (i >= n) */
  85   gcc_jit_block_end_with_conditional (
  86     b_loop_cond, NULL,
  87     gcc_jit_context_new_comparison (
  88        ctxt, NULL,
  89        GCC_JIT_COMPARISON_GE,
  90        gcc_jit_lvalue_as_rvalue (i),
  91        gcc_jit_param_as_rvalue (n)),
  92     b_after_loop,
  93     b_loop_body);
  94
  95   /* sum += i * i */
  96   gcc_jit_block_add_assignment_op (
  97     b_loop_body, NULL,
  98     sum,
  99     GCC_JIT_BINARY_OP_PLUS,
 100     gcc_jit_context_new_binary_op (
 101       ctxt, NULL,
 102       GCC_JIT_BINARY_OP_MULT, the_type,
 103       gcc_jit_lvalue_as_rvalue (i),
 104       gcc_jit_lvalue_as_rvalue (i)));
 105
 106   /* i++ */
 107   gcc_jit_block_add_assignment_op (
 108     b_loop_body, NULL,
 109     i,
 110     GCC_JIT_BINARY_OP_PLUS,
 111     gcc_jit_context_one (ctxt, the_type));
 112
 113   gcc_jit_block_end_with_jump (b_loop_body, NULL, b_loop_cond);
 114
 115   /* return sum */
 116   gcc_jit_block_end_with_return (
 117     b_after_loop,
 118     NULL,
 119     gcc_jit_lvalue_as_rvalue (sum));
 120 }
 121
 122 int
 123 main (int argc, char **argv)
 124 {
 125   gcc_jit_context *ctxt = NULL;
 126   gcc_jit_result *result = NULL;
 127
 128   /* Get a "context" object for working with the library.  */
 129   ctxt = gcc_jit_context_acquire ();
 130   if (!ctxt)
 131     {
 132       fprintf (stderr, "NULL ctxt");
 133       goto error;
 134     }
 135
 136   /* Set some options on the context.
 137      Let's see the code being generated, in assembler form.  */
 138   gcc_jit_context_set_bool_option (
 139     ctxt,
 140     GCC_JIT_BOOL_OPTION_DUMP_GENERATED_CODE,
 141     0);
 142
 143   /* Populate the context.  */
 144   create_code (ctxt);
 145
 146   /* Compile the code.  */
 147   result = gcc_jit_context_compile (ctxt);
 148   if (!result)
 149     {
 150       fprintf (stderr, "NULL result");
 151       goto error;
 152     }
 153
 154   /* Extract the generated code from "result".  */
 155   typedef int (*loop_test_fn_type) (int);
 156   loop_test_fn_type loop_test =
 157     (loop_test_fn_type)gcc_jit_result_get_code (result, "loop_test");
 158   if (!loop_test)
 159     {
 160       fprintf (stderr, "NULL loop_test");
 161       goto error;
 162     }
 163
 164   /* Run the generated code.  */
 165   int val = loop_test (10);
 166   printf("loop_test returned: %d\n", val);
 167
 168  error:
 169   gcc_jit_context_release (ctxt);
 170   gcc_jit_result_release (result);
 171   return 0;
 172 }