gcc/jit/docs/examples/tut01-hello-world.c

   1 /* Smoketest example for libgccjit.so
   2    Copyright (C) 2014 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 static void
  26 create_code (gcc_jit_context *ctxt)
  27 {
  28   /* Let's try to inject the equivalent of:
  29      void
  30      greet (const char *name)
  31      {
  32         printf ("hello %s\n", name);
  33      }
  34   */
  35   gcc_jit_type *void_type =
  36     gcc_jit_context_get_type (ctxt, GCC_JIT_TYPE_VOID);
  37   gcc_jit_type *const_char_ptr_type =
  38     gcc_jit_context_get_type (ctxt, GCC_JIT_TYPE_CONST_CHAR_PTR);
  39   gcc_jit_param *param_name =
  40     gcc_jit_context_new_param (ctxt, NULL, const_char_ptr_type, "name");
  41   gcc_jit_function *func =
  42     gcc_jit_context_new_function (ctxt, NULL,
  43                                   GCC_JIT_FUNCTION_EXPORTED,
  44                                   void_type,
  45                                   "greet",
  46                                   1, &param_name,
  47                                   0);
  48
  49   gcc_jit_param *param_format =
  50     gcc_jit_context_new_param (ctxt, NULL, const_char_ptr_type, "format");
  51   gcc_jit_function *printf_func =
  52     gcc_jit_context_new_function (ctxt, NULL,
  53                                   GCC_JIT_FUNCTION_IMPORTED,
  54                                   gcc_jit_context_get_type (
  55                                      ctxt, GCC_JIT_TYPE_INT),
  56                                   "printf",
  57                                   1, &param_format,
  58                                   1);
  59   gcc_jit_rvalue *args[2];
  60   args[0] = gcc_jit_context_new_string_literal (ctxt, "hello %s\n");
  61   args[1] = gcc_jit_param_as_rvalue (param_name);
  62
  63   gcc_jit_block *block = gcc_jit_function_new_block (func, NULL);
  64
  65   gcc_jit_block_add_eval (
  66     block, NULL,
  67     gcc_jit_context_new_call (ctxt,
  68                               NULL,
  69                               printf_func,
  70                               2, args));
  71   gcc_jit_block_end_with_void_return (block, NULL);
  72 }
  73
  74 int
  75 main (int argc, char **argv)
  76 {
  77   gcc_jit_context *ctxt;
  78   gcc_jit_result *result;
  79
  80   /* Get a "context" object for working with the library.  */
  81   ctxt = gcc_jit_context_acquire ();
  82   if (!ctxt)
  83     {
  84       fprintf (stderr, "NULL ctxt");
  85       exit (1);
  86     }
  87
  88   /* Set some options on the context.
  89      Let's see the code being generated, in assembler form.  */
  90   gcc_jit_context_set_bool_option (
  91     ctxt,
  92     GCC_JIT_BOOL_OPTION_DUMP_GENERATED_CODE,
  93     0);
  94
  95   /* Populate the context.  */
  96   create_code (ctxt);
  97
  98   /* Compile the code.  */
  99   result = gcc_jit_context_compile (ctxt);
 100   if (!result)
 101     {
 102       fprintf (stderr, "NULL result");
 103       exit (1);
 104     }
 105
 106   /* Extract the generated code from "result".  */
 107   typedef void (*fn_type) (const char *);
 108   fn_type greet =
 109     (fn_type)gcc_jit_result_get_code (result, "greet");
 110   if (!greet)
 111     {
 112       fprintf (stderr, "NULL greet");
 113       exit (1);
 114     }
 115
 116   /* Now call the generated function: */
 117   greet ("world");
 118   fflush (stdout);
 119
 120   gcc_jit_context_release (ctxt);
 121   gcc_jit_result_release (result);
 122   return 0;
 123 }