1 files changed, 201 insertions, 0 deletions
diff --git a/src/psl/psl-cse.adb b/src/psl/psl-cse.adb
new file mode 100644
index 000000000..5d6f3df13
--- /dev/null
+++ b/src/psl/psl-cse.adb
@@ -0,0 +1,201 @@
+with Ada.Text_IO;
+with PSL.Prints;
+with Types; use Types;
+
+package body PSL.CSE is
+   function Is_X_And_Not_X (A, B : Node) return Boolean is
+   begin
+      return (Get_Kind (A) = N_Not_Bool
+                and then Get_Boolean (A) = B)
+        or else (Get_Kind (B) = N_Not_Bool
+                   and then Get_Boolean (B) = A);
+   end Is_X_And_Not_X;
+
+   type Hash_Table_Type is array (Uns32 range 0 .. 128) of Node;
+   Hash_Table : Hash_Table_Type := (others => Null_Node);
+
+   function Compute_Hash (L, R : Node; Op : Uns32) return Uns32
+   is
+   begin
+      return Shift_Left (Get_Hash (L), 12)
+        xor Shift_Left (Get_Hash (R), 2)
+        xor Op;
+   end Compute_Hash;
+
+   function Compute_Hash (L: Node; Op : Uns32) return Uns32
+   is
+   begin
+      return Shift_Left (Get_Hash (L), 2) xor Op;
+   end Compute_Hash;
+
+   procedure Dump_Hash_Table (Level : Natural := 0)
+   is
+      use Ada.Text_IO;
+      Cnt : Natural;
+      Total : Natural;
+      N : Node;
+   begin
+      Total := 0;
+      for I in Hash_Table_Type'Range loop
+         Cnt := 0;
+         N := Hash_Table (I);
+         while N /= Null_Node loop
+            Cnt := Cnt + 1;
+            N := Get_Hash_Link (N);
+         end loop;
+         Put_Line ("Hash_table(" & Uns32'Image (I)
+                     & "):" & Natural'Image (Cnt));
+         Total := Total + Cnt;
+         if Level > 0 then
+            Cnt := 0;
+            N := Hash_Table (I);
+            while N /= Null_Node loop
+               Put (Uns32'Image (Get_Hash (N)));
+               if Level > 1 then
+                  Put (": ");
+                  PSL.Prints.Dump_Expr (N);
+                  New_Line;
+               end if;
+               Cnt := Cnt + 1;
+               N := Get_Hash_Link (N);
+            end loop;
+            if Level = 1 and then Cnt > 0 then
+               New_Line;
+            end if;
+         end if;
+      end loop;
+      Put_Line ("Total:" & Natural'Image (Total));
+   end Dump_Hash_Table;
+
+   function Build_Bool_And (L, R : Node) return Node
+   is
+      R1 : Node;
+      Res : Node;
+      Hash : Uns32;
+      Head, H : Node;
+   begin
+      if L = True_Node then
+         return R;
+      elsif R = True_Node then
+         return L;
+      elsif L = False_Node or else R = False_Node then
+         return False_Node;
+      elsif L = R then
+         return L;
+      elsif Is_X_And_Not_X (L, R) then
+         return False_Node;
+      end if;
+
+      --  More simple optimizations.
+      if Get_Kind (R) = N_And_Bool then
+         R1 := Get_Left (R);
+         if L = R1 then
+            return R;
+         elsif Is_X_And_Not_X (L, R1) then
+            return False_Node;
+         end if;
+      end if;
+
+      Hash := Compute_Hash (L, R, 2);
+      Head := Hash_Table (Hash mod Hash_Table'Length);
+      H := Head;
+      while H /= Null_Node loop
+         if Get_Hash (H) = Hash
+           and then Get_Kind (H) = N_And_Bool
+           and then Get_Left (H) = L
+           and then Get_Right (H) = R
+         then
+            return H;
+         end if;
+         H := Get_Hash_Link (H);
+      end loop;
+
+      Res := Create_Node (N_And_Bool);
+      Set_Left (Res, L);
+      Set_Right (Res, R);
+      Set_Hash_Link (Res, Head);
+      Set_Hash (Res, Hash);
+      Hash_Table (Hash mod Hash_Table'Length) := Res;
+      return Res;
+   end Build_Bool_And;
+
+   function Build_Bool_Or (L, R : Node) return Node
+   is
+      Res : Node;
+      Hash : Uns32;
+      Head, H : Node;
+   begin
+      if L = True_Node then
+         return L;
+      elsif R = True_Node then
+         return R;
+      elsif L = False_Node then
+         return R;
+      elsif R = False_Node then
+         return L;
+      elsif L = R then
+         return L;
+      elsif Is_X_And_Not_X (L, R) then
+         return True_Node;
+      end if;
+
+      Hash := Compute_Hash (L, R, 3);
+      Head := Hash_Table (Hash mod Hash_Table'Length);
+      H := Head;
+      while H /= Null_Node loop
+         if Get_Hash (H) = Hash
+           and then Get_Kind (H) = N_Or_Bool
+           and then Get_Left (H) = L
+           and then Get_Right (H) = R
+         then
+            return H;
+         end if;
+         H := Get_Hash_Link (H);
+      end loop;
+
+      Res := Create_Node (N_Or_Bool);
+      Set_Left (Res, L);
+      Set_Right (Res, R);
+      Set_Hash_Link (Res, Head);
+      Set_Hash (Res, Hash);
+      Hash_Table (Hash mod Hash_Table'Length) := Res;
+      return Res;
+   end Build_Bool_Or;
+
+   function Build_Bool_Not (N : Node) return Node is
+      Res : Node;
+      Hash : Uns32;
+      Head : Node;
+      H : Node;
+   begin
+      if N = True_Node then
+         return False_Node;
+      elsif N = False_Node then
+         return True_Node;
+      elsif Get_Kind (N) = N_Not_Bool then
+         return Get_Boolean (N);
+      end if;
+
+      --  Find in hash table.
+      Hash := Compute_Hash (N, 1);
+      Head := Hash_Table (Hash mod Hash_Table'Length);
+      H := Head;
+      while H /= Null_Node loop
+         if Get_Hash (H) = Hash
+           and then Get_Kind (H) = N_Not_Bool
+           and then Get_Boolean (H) = N
+         then
+            return H;
+         end if;
+         H := Get_Hash_Link (H);
+      end loop;
+
+      Res := Create_Node (N_Not_Bool);
+      Set_Boolean (Res, N);
+      Set_Hash_Link (Res, Head);
+      Set_Hash (Res, Hash);
+      Hash_Table (Hash mod Hash_Table'Length) := Res;
+
+      return Res;
+   end Build_Bool_Not;
+end PSL.CSE;