diff options
Diffstat (limited to 'src/synth/netlists-inference.adb')
| -rw-r--r-- | src/synth/netlists-inference.adb | 47 |
1 files changed, 37 insertions, 10 deletions
diff --git a/src/synth/netlists-inference.adb b/src/synth/netlists-inference.adb index e391a6769..0526988ca 100644 --- a/src/synth/netlists-inference.adb +++ b/src/synth/netlists-inference.adb @@ -469,6 +469,7 @@ package body Netlists.Inference is -- LAST_MUX is the mux whose input 0 is the loop and clock for selector. function Infere_FF (Ctxt : Context_Acc; + Val : Net; Prev_Val : Net; Off : Uns32; Last_Mux : Instance; @@ -513,17 +514,20 @@ package body Netlists.Inference is declare Done : Boolean; Mux : Instance; + -- Previous mux to be free. + Prev_Mux : Instance; Sel : Net; Last_Out : Net; Mux_Not_Rst : Net; Mux_Rst : Net; Mux_Rst_Val : Net; begin + Prev_Mux := No_Instance; Last_Out := O; -- Initially, the final output is not connected. So walk from the -- clocked mux until reaching the final output. - Done := not Is_Connected (Last_Out); + Done := Last_Out = Val; while not Done loop if not Has_One_Connection (Last_Out) @@ -542,12 +546,10 @@ package body Netlists.Inference is if Get_Driver (Get_Mux2_I0 (Mux)) = Last_Out then Mux_Rst_Val := Get_Driver (Get_Mux2_I1 (Mux)); Mux_Rst := Sel; - elsif Get_Driver (Get_Mux2_I1 (Mux)) = Last_Out then + else + pragma Assert (Get_Driver (Get_Mux2_I1 (Mux)) = Last_Out); Mux_Rst_Val := Get_Driver (Get_Mux2_I0 (Mux)); Mux_Rst := Build_Monadic (Ctxt, Id_Not, Sel); - else - -- Cannot happen. - raise Internal_Error; end if; Last_Out := Get_Output (Mux, 0); @@ -579,6 +581,11 @@ package body Netlists.Inference is else Enable := Build_Dyadic (Ctxt, Id_And, Enable, Mux_Not_Rst); end if; + + if Prev_Mux /= No_Instance then + Remove_Instance (Prev_Mux); + end if; + Prev_Mux := Mux; else -- Assume this is a reset value. -- FIXME: check for no logical loop. @@ -592,7 +599,11 @@ package body Netlists.Inference is -- The output of the mux is now the reset value. Redirect_Inputs (Last_Out, Mux_Rst_Val); - Free_Instance (Mux); + + if Prev_Mux /= No_Instance then + Remove_Instance (Prev_Mux); + end if; + Prev_Mux := Mux; Rst := Mux_Rst; Rst_Val := Mux_Rst_Val; @@ -600,12 +611,19 @@ package body Netlists.Inference is else Rst := Build_Dyadic (Ctxt, Id_Or, Mux_Rst, Rst); Rst_Val := Last_Out; + + if Prev_Mux /= No_Instance then + Remove_Instance (Prev_Mux); + end if; + Prev_Mux := No_Instance; end if; end if; end loop; - end; - Free_Instance (Last_Mux); + if Prev_Mux /= No_Instance then + Free_Instance (Mux); + end if; + end; if Off = 0 and then Can_Infere_RAM (Data, Prev_Val) @@ -629,6 +647,12 @@ package body Netlists.Inference is -- Create the FF. Res := Infere_FF_Create (Ctxt, Rst, Rst_Val, Init, Clk, Data, Els, Mux_Loc); + + -- The output may already be used (if the target is a variable that + -- is read). So redirect the net. + Redirect_Inputs (Get_Output (Last_Mux, 0), Res); + Free_Instance (Last_Mux); + return Res; end Infere_FF; @@ -762,7 +786,7 @@ package body Netlists.Inference is is pragma Assert (Val /= No_Net); pragma Assert (Prev_Val /= No_Net); - Last_Mux : Instance; + First_Mux, Last_Mux : Instance; Len : Integer; Sel : Input; Clk : Net; @@ -789,7 +813,10 @@ package body Netlists.Inference is Res := Infere_Latch (Ctxt, Val, Prev_Val, Stmt); else -- Clock -> FF - Res := Infere_FF (Ctxt, Prev_Val, Off, Last_Mux, + First_Mux := Get_Net_Parent (Val); + pragma Assert (Get_Id (First_Mux) = Id_Mux2); + + Res := Infere_FF (Ctxt, Val, Prev_Val, Off, Last_Mux, Clk, Enable, Stmt); end if; |