1 /* Copyright (C) 1998 - 2000 by Universitaet Karlsruhe
2 ** All rights reserved.
4 ** Authors: Christian Schaefer, Goetz Lindenmaier
15 * das leere FIRM Programm
19 *** This file constructs the ir for the following pseudo-program:
33 int main(int argc, char **argv)
35 ir_graph *irg; /* this variable contains the irgraph */
36 type_class *owner; /* the class in which this method is defined */
37 type_method *method; /* the type of this method */
38 entity *ent; /* represents this method as entity of owner */
39 ir_node *x, *x_then, *x_else, *c0, *c1, *c2, *cmpGt, *f, *t, *b;
41 printf("\ncreating an IR graph: IF_ELSE_EXAMPLE...\n");
46 /* FIRM was designed for oo languages where all methods belong to a class.
47 * For imperative languages like C we view a file as a large class containing
48 * all functions as methods in this file.
49 * Therefore we define a class "IF_ELSE_EXAMPLE" with a method main as an
52 #define ENTITYNAME "main"
54 owner = get_glob_type();
55 method = new_type_method (id_from_str("main", 4), 0, 2);
56 ent = new_entity ((type *)owner, id_from_str (ENTITYNAME,
57 strlen(ENTITYNAME)), (type *)method);
59 /* Generates the basic graph for the method represented by entity ent, that
60 * is, generates start and end blocks and nodes and a first, initial block.
61 * The constructor needs to know how many local variables the method has.
63 #define NUM_OF_LOCAL_VARS 2
65 irg = new_ir_graph (ent, NUM_OF_LOCAL_VARS);
67 /* Generate two constants */
68 c0 = new_Const (mode_i, tarval_from_long (mode_i, 0));
69 c1 = new_Const (mode_i, tarval_from_long (mode_i, 1));
71 /* set a and b to constants */
72 set_value (0, c0); /* this (0) is variable a */
73 set_value (1, c1); /* this (1) is variable b */
75 /* the expression that evaluates the condition */
76 c2 = new_Const (mode_i, tarval_from_long (mode_i, 2));
77 cmpGt = new_Proj(new_Cmp(get_value(0, mode_i), c2), mode_b, Gt);
79 /* the conditional branch */
81 f = new_Proj (x, mode_X, 0); /* if condition is false */
82 t = new_Proj (x, mode_X, 1); /* if condition is true */
84 mature_block (get_irg_current_block(irg));
86 /* generate and fill the then block */
89 set_value (0, get_value(1, mode_i));
93 /* generate and fill the else block */
96 set_value (1, new_Const (mode_i, tarval_from_long (mode_i, 2)));
100 /* generate the join block and add all cfg edges */
102 add_in_edge (b, x_then);
103 add_in_edge (b, x_else);
105 /* Generate the return node into current region. */
107 ir_node *in[2]; /* this is the array containing the return parameters */
108 in[0] = get_value(0, mode_i);
109 in[1] = get_value(1, mode_i);
110 x = new_Return (get_store(), 2, in);
112 /* Now generate all instructions for this block and all its predecessor
113 blocks so we can mature it. */
114 mature_block (get_irg_current_block(irg));
116 /* This adds the in edge of the end block which originates at the
117 return statement. The return node passes control flow to the
119 add_in_edge (get_irg_end_block(irg), x);
120 /* Now we can mature the end block as all it's predecessors are known. */
121 mature_block (get_irg_end_block(irg));
123 printf("\nOptimizing ...\n");
124 local_optimize_graph(irg);
125 //dead_node_elimination(irg);
127 /* verify the graph */
130 printf("Done building the graph. Dumping it.\n");
131 //dump_ir_graph (irg);
132 dump_ir_block_graph (irg);
133 printf("use xvcg to view this graph:\n");
134 printf("/ben/goetz/bin/xvcg GRAPHNAME\n\n");