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("creating 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 CLASSNAME "IF_ELSE_EXAMPLE"
53 #define ENTITYNAME "main"
55 owner = new_type_class (id_from_str (CLASSNAME, strlen(CLASSNAME)));
56 method = new_type_method (id_from_str("main", 4), 0, 2);
57 ent = new_entity ((type *)owner, id_from_str (ENTITYNAME, strlen(ENTITYNAME)), (type *)method);
60 /* Generates the basic graph for the method represented by entity ent, that
61 * is, generates start and end blocks and nodes and a first, initial block.
62 * The constructor needs to know how many local variables the method has.
64 #define NUM_OF_LOCAL_VARS 2
66 irg = new_ir_graph (ent, NUM_OF_LOCAL_VARS);
68 /* Generate two constants */
69 c0 = new_Const (mode_i, tarval_from_long (mode_i, 0));
70 c1 = new_Const (mode_i, tarval_from_long (mode_i, 1));
72 /* set a and b to constants */
73 set_value (0, c0); /* this (0) is variable a */
74 set_value (1, c1); /* this (1) is variable b */
76 /* the expression that evaluates the condition */
77 c2 = new_Const (mode_i, tarval_from_long (mode_i, 2));
78 cmpGt = new_Proj(new_Cmp(get_value(0, mode_i), c2), mode_b, Gt);
80 /* the conditional branch */
82 f = new_Proj (x, mode_X, 0); /* if condition is false */
83 t = new_Proj (x, mode_X, 1); /* if condition is true */
85 mature_block (irg->current_block);
87 /* generate and fill the then block */
90 set_value (0, get_value(1, mode_i));
94 /* generate and fill the else block */
97 set_value (1, new_Const (mode_i, tarval_from_long (mode_i, 2)));
101 /* generate the join block and add all cfg edges */
103 add_in_edge (b, x_then);
104 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 blocks
115 * so we can mature it. */
116 mature_block (irg->current_block);
118 /* This adds the in edge of the end block which originates at the return statement.
119 * The return node passes controlflow to the end block. */
120 add_in_edge (irg->end_block, x);
121 /* Now we can mature the end block as all it's predecessors are known. */
122 mature_block (irg->end_block);
124 /* verify the graph */
127 printf("\nDone building the graph. Dumping it.\n");
128 dump_ir_block_graph (irg);
130 printf("use xvcg to view this graph:\n");
131 printf("/ben/goetz/bin/xvcg GRAPHNAME\n");