fixed some minor bugs

[libfirm] / ir / be / bera.c

diff --git a/ir/be/bera.c b/ir/be/bera.c
index 7bddee0..024452a 100644 (file)
--- a/ir/be/bera.c
+++ b/ir/be/bera.c
@@ -3,23 +3,100 @@
  * @author Sebastian Hack
  * @date 22.11.2004
  */
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
 
 #include "pset.h"
 #include "impl.h"
 
 #include "irnode.h"
 #include "irmode.h"
-#include "besched.h"
+#include "irdom.h"
 
-#include "bera_t.h"
+#include "beutil.h"
+#include "besched_t.h"
+#include "belive_t.h"
 
-FIRM_IMPL1(is_allocatable_irn, int, const ir_node *)
+int value_dominates(const ir_node *a, const ir_node *b)
+{
+  int res = 0;
+       const ir_node *ba = get_block(a);
+       const ir_node *bb = get_block(b);
+
+  /*
+   * a and b are not in the same block,
+   * so dominance is determined by the dominance of the blocks.
+   */
+  if(ba != bb)
+    res = block_dominates(ba, bb);
+
+  /*
+   * Dominance is determined by the time steps of the schedule.
+   */
+  else {
+    sched_timestep_t as = sched_get_time_step(a);
+    sched_timestep_t bs = sched_get_time_step(b);
+    res = as <= bs;
+  }
 
-size_t ra_irn_data_offset = 0;
-size_t ra_irg_data_offset = 0;
+  return res;
+}
 
-void be_ra_init(void)
+/**
+ * Check, if two values interfere.
+ * @param a The first value.
+ * @param b The second value.
+ * @return 1, if a and b interfere, 0 if not.
+ */
+int values_interfere(const ir_node *a, const ir_node *b)
 {
-       ra_irn_data_offset = register_additional_node_data(sizeof(ra_info_t));
-       ra_irg_data_offset = register_additional_graph_data(sizeof(void *));
+  int a2b = value_dominates(a, b);
+  int b2a = value_dominates(b, a);
+
+  /* If there is no dominance relation, they do not interfere. */
+  if((a2b | b2a) > 0) {
+    const ir_edge_t *edge;
+    ir_node *bb;
+
+    /*
+     * Adjust a and b so, that a dominates b if
+     * a dominates b or vice versa.
+     */
+    if(b2a) {
+      const ir_node *t = a;
+      a = b;
+      b = t;
+    }
+
+               bb = get_nodes_block(b);
+
+    /*
+     * If a is live end in b's block it is
+     * live at b's definition (a dominates b)
+     */
+    if(is_live_end(bb, a))
+      return 1;
+
+    /*
+     * Look at all usages of a.
+     * If there's one usage of a in the block of b, then
+     * we check, if this use is dominated by b, if that's true
+     * a and b interfere. Note that b must strictly dominate the user,
+                * since if b is the last user of in the block, b and a do not
+                * interfere.
+     * Uses of a not in b's block can be disobeyed, because the
+     * check for a being live at the end of b's block is already
+     * performed.
+     */
+    foreach_out_edge(a, edge) {
+      const ir_node *user = edge->src;
+      if(get_nodes_block(user) == bb
+          && !is_Phi(user)
+                                       && b != user
+          && value_dominates(b, user))
+        return 1;
+    }
+  }
+  return 0;
 }