Fix and test for balanced case

diff --git a/passes/opt/muxpack.cc b/passes/opt/muxpack.cc
index f9e5c8f092372bba12246d5fdda894967c3f99ed..8c4db4e4d8ce642c70b6789119e5133464f2edf0 100644 (file)
--- a/passes/opt/muxpack.cc
+++ b/passes/opt/muxpack.cc
@@ -94,23 +94,27 @@ struct MuxpackWorker
                {
                        log_debug("Considering %s (%s)\n", log_id(cell), log_id(cell->type));
 
-                       SigSpec next_sig = cell->getPort("\\A");
-                       if (sig_chain_prev.count(next_sig) == 0) {
-                               if (cell->type == "$mux") {
-                                       next_sig = cell->getPort("\\B");
-                                       if (sig_chain_prev.count(next_sig) == 0)
-                                               goto start_cell;
-                               }
-                               else
+                       SigSpec a_sig = cell->getPort("\\A");
+                       if (cell->type == "$mux") {
+                               SigSpec b_sig = cell->getPort("\\B");
+                               if (sig_chain_prev.count(a_sig) + sig_chain_prev.count(b_sig) != 1)
+                                       goto start_cell;
+
+                               if (!sig_chain_prev.count(a_sig))
+                                       a_sig = b_sig;
+                       }
+                       else if (cell->type == "$pmux") {
+                               if (!sig_chain_prev.count(a_sig))
                                        goto start_cell;
                        }
+                       else log_abort();
 
                        {
-                               for (auto bit : next_sig.bits())
+                               for (auto bit : a_sig.bits())
                                        if (sigbit_with_non_chain_users.count(bit))
                                                goto start_cell;
 
-                               Cell *c1 = sig_chain_prev.at(next_sig);
+                               Cell *c1 = sig_chain_prev.at(a_sig);
                                Cell *c2 = cell;
 
                                if (c1->getParam("\\WIDTH") != c2->getParam("\\WIDTH"))

diff --git a/tests/various/muxpack.v b/tests/various/muxpack.v
index 7c189fff88bd95da32d5ff6a442d6275de977f37..f1bd5ea8e25d6521d85fe940ad1adbcc9bd19396 100644 (file)
--- a/tests/various/muxpack.v
+++ b/tests/various/muxpack.v
@@ -110,3 +110,29 @@ always @* begin
     endcase
 end
 endmodule
+
+module mux_if_bal_8_2 #(parameter N=8, parameter W=2) (input [N*W-1:0] i, input [$clog2(N)-1:0] s, output reg [W-1:0] o);
+always @*
+    if (s[0] == 1'b0)
+     if (s[1] == 1'b0)
+      if (s[2] == 1'b0)
+       o <= i[0*W+:W];
+      else
+       o <= i[1*W+:W];
+     else
+      if (s[2] == 1'b0)
+       o <= i[2*W+:W];
+      else
+       o <= i[3*W+:W];
+    else
+     if (s[1] == 1'b0)
+      if (s[2] == 1'b0)
+       o <= i[4*W+:W];
+      else
+       o <= i[5*W+:W];
+     else
+      if (s[2] == 1'b0)
+       o <= i[6*W+:W];
+      else
+       o <= i[7*W+:W];
+endmodule

diff --git a/tests/various/muxpack.ys b/tests/various/muxpack.ys
index 0c5b828189a0017f6fd21e8f1c6206aea89397a2..9ea743b9ffba7006784e2ac56298524af410c148 100644 (file)
--- a/tests/various/muxpack.ys
+++ b/tests/various/muxpack.ys
@@ -133,3 +133,18 @@ design -import gold -as gold
 design -import gate -as gate
 miter -equiv -flatten -make_assert -make_outputs gold gate miter
 sat -verify -prove-asserts -show-ports miter
+
+design -load read
+hierarchy -top mux_if_bal_8_2
+prep
+design -save gold
+muxpack
+opt
+stat
+select -assert-count 7 t:$mux
+select -assert-count 0 t:$pmux
+design -stash gate
+design -import gold -as gold
+design -import gate -as gate
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports miter