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.
58 ir_node *a, *b, *x, *y, *r;
60 printf("creating an IR graph: MEMORY_EXAMPLE...\n");
64 /* a class to get started with, containing the main procedure */
65 owner = new_type_class (id_from_str ("MEMORY_EXAMPLE", 14));
66 ent = new_entity ((type *)owner, id_from_str ("main", 4), NULL);
68 /* Generates start and end blocks and nodes and a first, initial block */
69 irg = new_ir_graph (ent, 4);
71 /* generate two constant pointers to string constants */
72 /* this simulates two global variables, a and b point to these variables */
73 a = new_Const (mode_p, tarval_p_from_str ("VAR_A"));
74 b = new_Const (mode_p, tarval_p_from_str ("VAR_B"));
76 /* set VAR_A and VAR_B to constant values */
77 set_store (new_Proj (new_Store (get_store (), a,
78 new_Const (mode_I, tarval_from_long (mode_i, 0))),
81 set_store (new_Proj (new_Store (get_store (), b,
82 new_Const (mode_I, tarval_from_long (mode_i, 1))),
85 /* finish this first block */
87 mature_block (irg->current_block);
93 /* exchange the content of the two variables. Exceptions not cached. */
94 /* load the value and make it's effects visible. */
95 x = new_Load (get_store (), a);
96 set_store (new_Proj (x, mode_M, 0));
97 x = new_Proj(x, mode_I, 2);
98 /* the same again: load the value and make it's effects visible. */
99 y = new_Load (get_store (), b);
100 set_store (new_Proj (y, mode_M, 0));
101 y = new_Proj(y, mode_I, 2);
102 /* store the exchanged values. */
103 set_store (new_Proj (new_Store (get_store (), a, y), mode_M, 0));
104 set_store (new_Proj (new_Store (get_store (), b, x), mode_M, 0));
106 /* test the condition */
110 new_Const (mode_I, tarval_from_long (mode_i, 0)),
113 /* build the cfg of the loop */
114 add_in_edge (r, new_Proj (x, mode_X, 0));
115 x = new_Proj (x, mode_X, 1);
118 /* generate the block the loop exits to */
122 /* generate the return block and return the content of VAR_A */
125 x = new_Load (get_store (), a);
126 in[0] = new_Proj (x, mode_I, 2);
128 x = new_Return (new_Proj(x, mode_M, 0), 1, in);
131 add_in_edge (irg->end_block, x);
132 mature_block (irg->end_block);
134 printf("\nDone building the graph. Dumping it.\n");
135 dump_ir_block_graph (irg);
137 printf("use xvcg to view this graph:\n");
138 printf("/ben/trapp/bin/i486/xvcg GRAPHNAME\n");