Merge remote-tracking branch 'origin/master' into eddie/abc9_refactor

diff --cc techlibs/xilinx/cells_sim.v
Simple merge

diff --cc techlibs/xilinx/synth_xilinx.cc
index f2a9ae9823c0d0cbc80f0297b0396dac148c0f7c,b0c4795eec655355f2153868eae63e75d04c4a01..2f4c503f236d013ab18a294be57edf1711afb463
--- 1/techlibs/xilinx/synth_xilinx.cc
--- 2/techlibs/xilinx/synth_xilinx.cc
+++ b/techlibs/xilinx/synth_xilinx.cc
@@@ -107,11 -107,8 +107,11 @@@ struct SynthXilinxPass : public ScriptP
                log("    -flatten\n");
                log("        flatten design before synthesis\n");
                log("\n");
 +              log("    -dff\n");
 +              log("        run 'abc9' with -dff option\n");
 +              log("\n");
                log("    -retime\n");
-               log("        run 'abc' with -dff option\n");
+               log("        run 'abc' with '-dff -D 1' options\n");
                log("\n");
                log("    -abc9\n");
                log("        use new ABC9 flow (EXPERIMENTAL)\n");