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-- PSL - Simplify expressions
-- Copyright (C) 2002-2016 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 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;
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