xilinx: Improve flip-flop handling.

This adds support for infering more kinds of flip-flops:

- FFs with async set/reset and clock enable
- FFs with sync set/reset
- FFs with sync set/reset and clock enable

Some passes have been moved (and some added) in order for dff2dffs to
work correctly.

This gives us complete coverage of Virtex 6+ and Spartan 6 flip-flop
capabilities (though not latch capabilities).  Older FPGAs also support
having both a set and a reset input, which will be handled at a later
data.

1 files changed, 4 insertions, 5 deletions

diff --git a/tests/arch/xilinx/adffs.ys b/tests/arch/xilinx/adffs.ys
index e73bfe0b9..c0ff6a2e2 100644
--- a/tests/arch/xilinx/adffs.ys
+++ b/tests/arch/xilinx/adffs.ys
@@ -32,10 +32,9 @@ equiv_opt -async2sync  -assert -map +/xilinx/cells_sim.v synth_xilinx # equivale
 design -load postopt # load the post-opt design (otherwise equiv_opt loads the pre-opt design)
 cd dffs # Constrain all select calls below inside the top module
 select -assert-count 1 t:BUFG
-select -assert-count 1 t:FDRE
-select -assert-count 1 t:LUT2
+select -assert-count 1 t:FDSE
 
-select -assert-none t:BUFG t:FDRE t:LUT2 %% t:* %D
+select -assert-none t:BUFG t:FDSE %% t:* %D
 
 
 design -load read
@@ -46,6 +45,6 @@ design -load postopt # load the post-opt design (otherwise equiv_opt loads the p
 cd ndffnr # Constrain all select calls below inside the top module
 select -assert-count 1 t:BUFG
 select -assert-count 1 t:FDRE_1
-select -assert-count 1 t:LUT2
+select -assert-count 1 t:INV
 
-select -assert-none t:BUFG t:FDRE_1 t:LUT2 %% t:* %D
+select -assert-none t:BUFG t:FDRE_1 t:INV %% t:* %D