synth-inference: detect false loop.

1 files changed, 89 insertions, 0 deletions

diff --git a/src/dyn_interning.ads b/src/dyn_interning.ads
new file mode 100644
index 000000000..2b5dc5ee4
--- /dev/null
+++ b/src/dyn_interning.ads
@@ -0,0 +1,89 @@
+--  Type interning - set of unique objects.
+--  Copyright (C) 2019 Tristan Gingold
+--
+--  GHDL is free software; you can redistribute it and/or modify it under
+--  the terms of the GNU General Public License as published by the Free
+--  Software Foundation; either version 2, or (at your option) any later
+--  version.
+--
+--  GHDL is distributed in the hope that it will be useful, but WITHOUT ANY
+--  WARRANTY; without even the implied warranty of MERCHANTABILITY or
+--  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+--  for more details.
+--
+--  You should have received a copy of the GNU General Public License
+--  along with GHDL; see the file COPYING.  If not, write to the Free
+--  Software Foundation, 59 Temple Place - Suite 330, Boston, MA
+--  02111-1307, USA.
+
+with Types; use Types;
+with Hash; use Hash;
+with Dyn_Tables;
+
+--  This generic package provides a factory to build unique objects.
+--  Get will return an existing object or create a new one.
+generic
+   --  Parameters of the object to be created.
+   type Params_Type (<>) is private;
+
+   --  Object to be built and stored.
+   type Object_Type is private;
+
+   --  Reduce PARAMS to a small value.
+   --  The required property is: Hash(P1) /= Hash(P2) => P1 /= P2.
+   with function Hash (Params : Params_Type) return Hash_Value_Type;
+
+   --  Create an object from PARAMS.
+   with function Build (Params : Params_Type) return Object_Type;
+
+   --  Return True iff OBJ is the object corresponding to PARAMS.
+   with function Equal (Obj : Object_Type; Params : Params_Type)
+                       return Boolean;
+package Dyn_Interning is
+   type Instance is limited private;
+
+   --  Initialize.  Required before any other operation.
+   procedure Init (Inst : out Instance);
+
+   procedure Free (Inst : in out Instance);
+
+   --  If there is already an existing object for PARAMS, return it.
+   --  Otherwise create it.
+   procedure Get
+     (Inst : in out Instance; Params : Params_Type; Res : out Object_Type);
+
+   type Index_Type is new Uns32;
+   No_Index : constant Index_Type := 0;
+   First_Index : constant Index_Type := 1;
+
+   --  Get the number of elements in the table.
+   function Last_Index (Inst : Instance) return Index_Type;
+
+   --  Get an element by index.  The index has no real meaning, but the
+   --  current implementation allocates index incrementally.
+   function Get_By_Index (Inst : Instance; Index : Index_Type)
+                         return Object_Type;
+private
+   type Element_Wrapper is record
+      Hash : Hash_Value_Type;
+      Next : Index_Type := No_Index;
+      Obj  : Object_Type;
+   end record;
+
+   package Wrapper_Tables is new Dyn_Tables
+     (Table_Index_Type => Index_Type,
+      Table_Component_Type => Element_Wrapper,
+      Table_Low_Bound => No_Index + 1,
+      Table_Initial => 128);
+
+   type Hash_Array is array (Hash_Value_Type range <>) of Index_Type;
+   type Hash_Array_Acc is access Hash_Array;
+
+   Initial_Size : constant Hash_Value_Type := 1024;
+
+   type Instance is record
+      Els : Wrapper_Tables.Instance;
+      Size : Hash_Value_Type;
+      Hash_Table : Hash_Array_Acc;
+   end record;
+end Dyn_Interning;