dfflegalize: Prefer mapping dff to sdff before adff

This ensures that, when both sync and async FFs are available and abc9
is involved, the sync FFs will be used, and will thus remain available
for sequential synthesis.

diff --git a/passes/techmap/dfflegalize.cc b/passes/techmap/dfflegalize.cc
index 7f2cdc6accea9e6f1317f6e3b35691861ebddd18..b2fe90702da7e1ff454fa5c3a2d47a9bd62b3fb7 100644 (file)
--- a/passes/techmap/dfflegalize.cc
+++ b/passes/techmap/dfflegalize.cc
@@ -364,7 +364,7 @@ flip_dqi:
                                // Some DFF is supported with this init val.  Just pick a type.
                                if (ff_type == FF_DFF) {
                                        // Try adding a set or reset pin.
-                                       for (auto new_type: {FF_ADFF0, FF_ADFF1, FF_SDFF0, FF_SDFF1})
+                                       for (auto new_type: {FF_SDFF0, FF_SDFF1, FF_ADFF0, FF_ADFF1})
                                                if (supported_cells[new_type] & initmask) {
                                                        ff_type = new_type;
                                                        sig_r = State::S0;