1 /* Copyright (C) 1998 - 2000 by Universitaet Karlsruhe
2 ** All rights reserved.
4 ** Authors: Christian Schaefer, Goetz Lindenmaier
12 /** This example demonstrates the use of memory edges.
13 *** This file constructs the ir for the following pseudo-program:
33 *** A better example would be the following program:
34 *** (name e.g.: memory-imp_example.c as it models imperative concepts.)
36 *** In this program a local variable is dereferenced. It has
37 *** to be modeled as an entity of the stack so that a pointer to it is available.
38 *** It is also an example where an analysis could find out that the
39 *** pointer is never actually used.
57 type *method; /* the type of this method */
59 ir_node *a, *b, *x, *y, *r;
61 printf("\nCreating an IR graph: MEMORY_EXAMPLE...\n");
65 set_opt_dead_node_elimination (1);
67 /* a class to get started with, containing the main procedure */
68 owner = new_type_class (id_from_str ("MEMORY_EXAMPLE", 14));
69 method = new_type_method (id_from_str("main", 4), 0, 2);
70 ent = new_entity (owner, id_from_str ("main", 4), method);
72 /* Generates start and end blocks and nodes and a first, initial block */
73 irg = new_ir_graph (ent, 4);
75 /* generate two constant pointers to string constants */
76 /* this simulates two global variables, a and b point to these variables */
77 a = new_Const (mode_p, tarval_p_from_str ("VAR_A"));
78 b = new_Const (mode_p, tarval_p_from_str ("VAR_B"));
80 /* set VAR_A and VAR_B to constant values */
81 set_store (new_Proj (new_Store (get_store (), a,
82 new_Const (mode_I, tarval_from_long (mode_i, 0))),
85 set_store (new_Proj (new_Store (get_store (), b,
86 new_Const (mode_I, tarval_from_long (mode_i, 1))),
89 /* finish this first block */
91 mature_block (get_irg_current_block(irg));
97 /* exchange the content of the two variables. Exceptions not cached. */
98 /* load the value and make it's effects visible. */
99 x = new_Load (get_store (), a);
100 set_store (new_Proj (x, mode_M, 0));
101 x = new_Proj(x, mode_I, 2);
102 /* the same again: load the value and make it's effects visible. */
103 y = new_Load (get_store (), b);
104 set_store (new_Proj (y, mode_M, 0));
105 y = new_Proj(y, mode_I, 2);
106 /* store the exchanged values. */
107 set_store (new_Proj (new_Store (get_store (), a, y), mode_M, 0));
108 set_store (new_Proj (new_Store (get_store (), b, x), mode_M, 0));
110 /* test the condition */
114 new_Const (mode_I, tarval_from_long (mode_i, 0)),
118 /* build the cfg of the loop */
119 add_in_edge (r, new_Proj (x, mode_X, 0));
120 x = new_Proj (x, mode_X, 1);
123 /* generate the block the loop exits to */
127 /* generate the return block and return the content of VAR_A */
130 x = new_Load (get_store (), a);
131 in[0] = new_Proj (x, mode_I, 2);
133 x = new_Return (new_Proj(x, mode_M, 0), 1, in);
136 add_in_edge (get_irg_end_block(irg), x);
137 mature_block (get_irg_end_block(irg));
139 printf("Optimizing ...\n");
140 dead_node_elimination(irg);
142 /* verify the graph */
145 printf("Done building the graph. Dumping it.\n");
146 dump_ir_block_graph (irg);
147 printf("Use xvcg to view this graph:\n");
148 printf("/ben/goetz/bin/xvcg GRAPHNAME\n\n");