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