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| author | Tristan Gingold <tgingold@free.fr> | 2019-09-28 08:16:40 +0200 |
|---|---|---|
| committer | Tristan Gingold <tgingold@free.fr> | 2019-09-28 08:16:40 +0200 |
| commit | 474cd4d40187c545abf8c3cd3213c3fd1cb98645 (patch) | |
| tree | 33fc6d2f339629bd62016c6d512ebaff760fbf2d | |
| parent | ed614df2af4debb68d6533d74a38ed35f9030e1c (diff) | |
| download | ghdl-474cd4d40187c545abf8c3cd3213c3fd1cb98645.tar.gz ghdl-474cd4d40187c545abf8c3cd3213c3fd1cb98645.tar.bz2 ghdl-474cd4d40187c545abf8c3cd3213c3fd1cb98645.zip | |
synth-environment: optimize cascaded if.
| -rw-r--r-- | src/synth/synth-environment.adb | 28 |
1 files changed, 27 insertions, 1 deletions
diff --git a/src/synth/synth-environment.adb b/src/synth/synth-environment.adb index b13c4dc89..8403e1066 100644 --- a/src/synth/synth-environment.adb +++ b/src/synth/synth-environment.adb @@ -20,6 +20,9 @@ with Netlists.Builders; use Netlists.Builders; with Netlists.Concats; +with Netlists.Gates; +with Netlists.Gates_Ports; + with Errorout; use Errorout; with Synth.Inference; @@ -872,6 +875,8 @@ package body Synth.Environment is T_Asgns : Partial_Assign; Stmt : Source.Syn_Src) is + use Netlists.Gates; + use Netlists.Gates_Ports; P : Partial_Assign_Array (0 .. 1); N : Net_Array (0 .. 1); Min_Off : Uns32; @@ -880,6 +885,7 @@ package body Synth.Environment is Res : Net; List : Partial_Assign_List; Pasgn : Partial_Assign; + N1_Inst : Instance; begin P := (0 => F_Asgns, 1 => T_Asgns); Partial_Assign_Init (List); @@ -899,8 +905,28 @@ package body Synth.Environment is end if; end loop; + -- Possible optimizations: + -- if C1 then _ _ _ + -- if C2 then R0-|0\ R0-|0\ R0 -|0\ + -- R := V; ==> | |--+ | |- R ==> | |- R + -- end if; V-|_/ +----|_/ V-|_/ + -- end if; C1 C2 C1.C2 + -- + -- This really helps inference as the net R0 doesn't have to be + -- walked twice (in absence of memoization). + -- Build mux. - Res := Netlists.Builders.Build_Mux2 (Ctxt, Sel, N (0), N (1)); + N1_Inst := Get_Net_Parent (N (1)); + if Get_Id (N1_Inst) = Id_Mux2 + and then Get_Driver (Get_Mux2_I0 (N1_Inst)) = N (0) + then + Res := Build_Mux2 + (Ctxt, Build_Dyadic (Ctxt, Id_And, + Sel, Get_Driver (Get_Mux2_Sel (N1_Inst))), + N (0), Get_Driver (Get_Mux2_I1 (N1_Inst))); + else + Res := Build_Mux2 (Ctxt, Sel, N (0), N (1)); + end if; Set_Location (Res, Stmt); -- Keep the result in a list. |