*/
/**
-* @file irloop.h
-*
-* Computes backedges in the control and data flow.
-*
-* @author Goetz Lindenmaier
-*
-* Only Block and Phi/Filter nodes can have incoming backedges.
-* Constructs loops data structure: indicates loop nesting.
-*/
+ * @file irloop.h
+ *
+ * Computes backedges in the control and data flow.
+ *
+ * @author Goetz Lindenmaier
+ *
+ * Only Block and Phi/Filter nodes can have incoming backedges.
+ * Constructs loops data structure: indicates loop nesting.
+ */
# ifndef _IRLOOP_H_
# define _IRLOOP_H_
*/
/* ------------------------------------------------------------------- */
-/** Returns true if the predesessor pos is a backedge. */
-bool is_backedge (ir_node *n, int pos);
-/** Remarks that edge pos is a backedge. */
+/** Returns true if the predecessor pos is a backedge in the interprozeduralem view. */
+int is_inter_backedge(ir_node *n, int pos);
+/** Returns true if the predecessor pos is a backedge in the intraprocedural view. */
+int is_intra_backedge(ir_node *n, int pos);
+/** Returns non-zero if the predecessor pos is a backedge. */
+int is_backedge (ir_node *n, int pos);
+/** Marks edge pos as a backedge. */
void set_backedge (ir_node *n, int pos);
-/** Remarks that edge pos is not a backedge. */
+/** Marks edge pos as a non-backedge. */
void set_not_backedge (ir_node *n, int pos);
-/** Returns true if n has backedges. */
-bool has_backedges (ir_node *n);
-/** Sets backedge information to zero. */
+/** Returns non-zero if n has backedges. */
+int has_backedges (ir_node *n);
+/** Clears all backedge information. */
void clear_backedges (ir_node *n);
/* ------------------------------------------------------------------- */
/**
- * The loops datastructure.
+ * The loops data structure.
*
- * The loops datastructure represents circles in the intermediate
+ * The loops data structure represents circles in the intermediate
* representation. It does not represent loops in the terms of a
* source program.
- * Each ir_graph can contain one outermost loop datastructure.
+ * Each ir_graph can contain one outermost loop data structure.
* loop is the entry point to the nested loops.
- * The loop datastructure contains a field indicating the depth of
+ * The loop data structure contains a field indicating the depth of
* the loop within the nesting. Further it contains a list of the
* loops with nesting depth -1. Finally it contains a list of all
* nodes in the loop.
* this would cost a lot of memory, though.
*/
/* ------------------------------------------------------------------- */
+#ifndef _IR_LOOP_TYPEDEF_
+#define _IR_LOOP_TYPEDEF_
typedef struct ir_loop ir_loop;
+#endif
-/* Loop elements are loop nodes and ir nodes */
+/** Loop elements: loop nodes and ir nodes */
typedef union {
firm_kind *kind; /**< is either k_ir_node or k_ir_loop */
ir_node *node; /**< Pointer to an ir_node element */
/** Set the outermost loop in ir graph as basic access to loop tree. */
void set_irg_loop(ir_graph *irg, ir_loop *l);
+
+/* Returns the root loop info (if exists) for an irg. */
ir_loop *get_irg_loop(ir_graph *irg);
/** Returns the loop n is contained in. NULL if node is in no loop. */
-ir_loop *get_irn_loop(ir_node *n);
+ir_loop *get_irn_loop(const ir_node *n);
/** Returns outer loop, itself if outermost. */
-ir_loop *get_loop_outer_loop (ir_loop *loop);
+ir_loop *get_loop_outer_loop (const ir_loop *loop);
/** Returns nesting depth of this loop */
-int get_loop_depth (ir_loop *loop);
+int get_loop_depth (const ir_loop *loop);
/* Sons are the inner loops contained in this loop. */
/** Returns the number of inner loops */
-int get_loop_n_sons (ir_loop *loop);
+int get_loop_n_sons (const ir_loop *loop);
+
+/** Returns the pos`th son loop (inner loop) of a loop.
+ Returns NULL if there is not a pos`th loop_node. */
ir_loop *get_loop_son (ir_loop *loop, int pos);
+
/** Returns the number of nodes contained in loop. */
int get_loop_n_nodes (ir_loop *loop);
+
+/** Returns the pos`th ir_node of a loop.
+ Returns NULL if there is not a pos`th ir_node. */
ir_node *get_loop_node (ir_loop *loop, int pos);
/** Returns the number of elements contained in loop. */
loop_element get_loop_element (ir_loop *loop, int pos);
/** Returns the element number of the loop son in loop.
- * Returns -1 if not found. O(#elements). */
+ * Returns -1 if not found. O(|elements|). */
int get_loop_element_pos(ir_loop *loop, void *le);
/** Returns a unique node number for the loop node to make output
/* Constructing and destructing the loop/backedge information. */
/* ------------------------------------------------------------------- */
-/** Constructs backedge information for irg in intraprocedural view.
- * @returns Maximal depth of loop tree. */
+/** Constructs backedge information and loop tree for a graph in intraprocedural view.
+ *
+ * The algorithm views the program representation as a pure graph.
+ * It assumes that only block and phi nodes may be loop headers.
+ * The resulting loop tree is a possible visiting order for dataflow
+ * analysis.
+ *
+ * This algorithm destoyes the link field of block nodes.
+ *
+ * @returns Maximal depth of loop tree.
+ *
+ * @remark
+ * One assumes, the Phi nodes in a block with a backedge have backedges
+ * at the same positions as the block. This is not the case, as
+ * the scc algorithms does not respect the program semantics in this case.
+ * Take a swap in a loop (t = i; i = j; j = t;) This results in two Phi
+ * nodes. They form a cycle. Once the scc algorithm deleted one of the
+ * edges, the cycle is removed. The second Phi node does not get a
+ * backedge!
+ */
/* @@@ Well, maybe construct_loop_information or analyze_loops ? */
int construct_backedges(ir_graph *irg);
-/** Constructs backedges for all irgs in interprocedural view. All
- loops in the graph will be marked as such, not only realizeable
- loops and recursions in the program. E.g., if the same funcion is
- called twice, there is a loop between the first function return and
- the second call.
- * @returns Maximal depth of loop tree. */
+/** Constructs backedges for all irgs in interprocedural view.
+ *
+ * @see As construct_backedges(), but for interprocedural view.
+ *
+ * @remark
+ * All loops in the graph will be marked as such, not only
+ * realizeable loops and recursions in the program. E.g., if the
+ * same funcion is called twice, there is a loop between the first
+ * function return and the second call.
+ *
+ * @returns Maximal depth of loop tree.
+*/
int construct_ip_backedges(void);
-/* Construct loop tree only for control flow.
- * @returns Maximal depth of loop tree. */
+/** Construct loop tree only for control flow.
+ *
+ * This constructs loop information resembling the program structure.
+ * It is useful for loop optimizations and analyses, as, e.g., finding
+ * iteration variables or loop invariant code motion.
+ *
+ * This algorithm computes only back edge information for Block nodes, not
+ * for Phi nodes.
+ *
+ * This algorithm destoyes the link field of block nodes.
+ *
+ * @returns Maximal depth of loop tree.
+ */
int construct_cf_backedges(ir_graph *irg);
+
+/** Construct interprocedural loop tree for control flow.
+ *
+ * @see construct_cf_backedges() and construct_ip_backedges().
+ */
int construct_ip_cf_backedges (void);
/** Removes all loop information.
- Resets all backedges */
+ * Resets all backedges. Works for any construction algorithm.
+ */
void free_loop_information(ir_graph *irg);
void free_all_loop_information (void);
* @param n The node to be tested.
* @param block A block node.
*
- * Returns true, if the node n is not changed in the loop block
+ * Returns non-zero, if the node n is not changed in the loop block
* belongs to or in inner loops of this block. */
int is_loop_invariant(ir_node *n, ir_node *block);
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