Check nusers for M and P enable muxes

diff --git a/passes/pmgen/xilinx_dsp.pmg b/passes/pmgen/xilinx_dsp.pmg
index 15343e21e66bffc504d7e5f49f26b1456c820273..8f83a2a508f19d9f7e93d2f5c3a368a1492315e0 100644 (file)
--- a/passes/pmgen/xilinx_dsp.pmg
+++ b/passes/pmgen/xilinx_dsp.pmg
@@ -134,10 +134,17 @@ endmatch
 
 match ffMmux
        select ffMmux->type.in($mux)
+       choice <IdString> BA {\B, \A}
+       // new-value net must have exactly two users: dsp and ffM
+       select nusers(port(ffMmux, BA)) == 2
+       define <IdString> AB (BA == \B ? \A : \B)
+       // keep-last-value net must have at least three users: ffMmux, ffM, downstream sink(s)
+       select nusers(port(ffMmux, AB)) >= 3
+       // ffMmux output must have two users: ffMmux and ffM.D
        select nusers(port(ffMmux, \Y)) == 2
        filter GetSize(port(ffMmux, \Y)) <= GetSize(sigM)
-       choice <IdString> BA {\B, \A}
        filter port(ffMmux, BA) == sigM.extract(0, GetSize(port(ffMmux, \Y)))
+       // Remaining bits on sigM must not have any other users
        filter nusers(sigM.extract_end(GetSize(port(ffMmux, BA)))) <= 1
        define <bool> pol (BA == \B)
        set ffMenpol pol
@@ -157,6 +164,7 @@ match ffM
        select nusers(port(ffM, \D)) == 2
        filter GetSize(port(ffM, \D)) <= GetSize(sigM)
        filter port(ffM, \D) == sigM.extract(0, GetSize(port(ffM, \D)))
+       // Remaining bits on sigM must not have any other users
        filter nusers(sigM.extract_end(GetSize(port(ffM, \D)))) <= 1
        // Check ffMmux (when present) is a $dff enable mux
        filter !ffMmux || port(ffM, \Q) == port(ffMmux, ffMenpol ? \A : \B)
@@ -221,10 +229,17 @@ endcode
 
 match ffPmux
        select ffPmux->type.in($mux)
+       choice <IdString> BA {\B, \A}
+       // new-value net must have exactly two users: dsp and ffP
+       select nusers(port(ffPmux, BA)) == 2
+       define <IdString> AB (BA == \B ? \A : \B)
+       // keep-last-value net must have at least three users: ffPmux, ffP, downstream sink(s)
+       select nusers(port(ffPmux, AB)) >= 3
+       // ffPmux output must have two users: ffPmux and ffP.D
        select nusers(port(ffPmux, \Y)) == 2
        filter GetSize(port(ffPmux, \Y)) <= GetSize(sigP)
-       choice <IdString> BA {\B, \A}
        filter port(ffPmux, BA) == sigP.extract(0, GetSize(port(ffPmux, \Y)))
+       // Remaining bits on sigP must not have any other users
        filter nusers(sigP.extract_end(GetSize(port(ffPmux, BA)))) <= 1
        define <bool> pol (BA == \B)
        set ffPenpol pol