2009-09-09 Richard Guenther <rguenther@suse.de>

[pf3gnuchains/gcc-fork.git] / gcc / tree-ssa.c

diff --git a/gcc/tree-ssa.c b/gcc/tree-ssa.c
index 0ff4733..9015d19 100644 (file)
--- a/gcc/tree-ssa.c
+++ b/gcc/tree-ssa.c
@@ -444,6 +444,74 @@ propagate_defs_into_debug_stmts (gimple def, basic_block tobb,
     }
 }
 
+/* Delete SSA DEFs for SSA versions in the TOREMOVE bitmap, removing
+   dominated stmts before their dominators, so that release_ssa_defs
+   stands a chance of propagating DEFs into debug bind stmts.  */
+
+void
+release_defs_bitset (bitmap toremove)
+{
+  unsigned j;
+  bitmap_iterator bi;
+
+  /* Performing a topological sort is probably overkill, this will
+     most likely run in slightly superlinear time, rather than the
+     pathological quadratic worst case.  */
+  while (!bitmap_empty_p (toremove))
+    EXECUTE_IF_SET_IN_BITMAP (toremove, 0, j, bi)
+      {
+       bool remove_now = true;
+       tree var = ssa_name (j);
+       gimple stmt;
+       imm_use_iterator uit;
+
+       FOR_EACH_IMM_USE_STMT (stmt, uit, var)
+         {
+           ssa_op_iter dit;
+           def_operand_p def_p;
+
+           /* We can't propagate PHI nodes into debug stmts.  */
+           if (gimple_code (stmt) == GIMPLE_PHI
+               || is_gimple_debug (stmt))
+             continue;
+
+           /* If we find another definition to remove that uses
+              the one we're looking at, defer the removal of this
+              one, so that it can be propagated into debug stmts
+              after the other is.  */
+           FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, dit, SSA_OP_DEF)
+             {
+               tree odef = DEF_FROM_PTR (def_p);
+
+               if (bitmap_bit_p (toremove, SSA_NAME_VERSION (odef)))
+                 {
+                   remove_now = false;
+                   break;
+                 }
+             }
+
+           if (!remove_now)
+             BREAK_FROM_IMM_USE_STMT (uit);
+         }
+
+       if (remove_now)
+         {
+           gimple def = SSA_NAME_DEF_STMT (var);
+           gimple_stmt_iterator gsi = gsi_for_stmt (def);
+
+           if (gimple_code (def) == GIMPLE_PHI)
+             remove_phi_node (&gsi, true);
+           else
+             {
+               gsi_remove (&gsi, true);
+               release_defs (def);
+             }
+
+           bitmap_clear_bit (toremove, j);
+         }
+      }
+}
+
 /* Return true if SSA_NAME is malformed and mark it visited.
 
    IS_VIRTUAL is true if this SSA_NAME was found inside a virtual
@@ -1895,7 +1963,8 @@ execute_update_addresses_taken (bool do_optimize)
            {
              gimple stmt = gsi_stmt (gsi);
 
-             if (gimple_references_memory_p (stmt))
+             if (gimple_references_memory_p (stmt)
+                 || is_gimple_debug (stmt))
                update_stmt (stmt);
            }