From 681b678417dafeadc6dd4f8d191911712e61ee7b Mon Sep 17 00:00:00 2001
From: "Emil J. Tywoniak" <emil@tywoniak.eu>
Date: Mon, 9 Dec 2024 14:18:08 +0100
Subject: [PATCH] dfflibmap: cover enable inference with test

---
 tests/techmap/dfflibmap-sim.v |  9 +++++++++
 tests/techmap/dfflibmap.lib   | 32 ++++++++++++++++++++++++++++----
 tests/techmap/dfflibmap.ys    | 23 ++++++++++++++---------
 3 files changed, 51 insertions(+), 13 deletions(-)

diff --git a/tests/techmap/dfflibmap-sim.v b/tests/techmap/dfflibmap-sim.v
index 1788a683bb5..42006a211af 100644
--- a/tests/techmap/dfflibmap-sim.v
+++ b/tests/techmap/dfflibmap-sim.v
@@ -20,3 +20,12 @@ always @(posedge CLK, posedge CLEAR, posedge PRESET)
 assign QN = ~Q;
 
 endmodule
+
+module dffe(input CLK, EN, D, output reg Q, output QN);
+
+always @(negedge CLK)
+	if (EN) Q <= D;
+
+assign QN = ~Q;
+
+endmodule
diff --git a/tests/techmap/dfflibmap.lib b/tests/techmap/dfflibmap.lib
index ce460877e61..d0cd472c3b0 100644
--- a/tests/techmap/dfflibmap.lib
+++ b/tests/techmap/dfflibmap.lib
@@ -5,7 +5,7 @@ library(test) {
     ff("IQ", "IQN") {
       next_state : "D";
       clocked_on : "!CLK";
-    } 
+    }
     pin(D) {
       direction : input;
     }
@@ -19,7 +19,7 @@ library(test) {
     pin(QN) {
       direction: output;
       function : "IQN";
-    } 
+    }
   }
   cell (dffsr) {
     area : 6;
@@ -30,7 +30,7 @@ library(test) {
       preset     : "PRESET";
       clear_preset_var1 : L;
       clear_preset_var2 : L;
-    } 
+    }
     pin(D) {
       direction : input;
     }
@@ -50,6 +50,30 @@ library(test) {
     pin(QN) {
       direction: output;
       function : "IQN";
-    } 
+    }
+  }
+  cell (dffe) {
+    area : 6;
+    ff("IQ", "IQN") {
+      next_state : "(D&EN) | (IQ&!EN)";
+      clocked_on : "!CLK";
+    }
+    pin(D) {
+      direction : input;
+    }
+    pin(EN) {
+      direction : input;
+    }
+    pin(CLK) {
+      direction : input;
+    }
+    pin(Q) {
+      direction: output;
+      function : "IQ";
+    }
+    pin(QN) {
+      direction: output;
+      function : "IQN";
+    }
   }
 }
diff --git a/tests/techmap/dfflibmap.ys b/tests/techmap/dfflibmap.ys
index e8b12545670..13fb82b475d 100644
--- a/tests/techmap/dfflibmap.ys
+++ b/tests/techmap/dfflibmap.ys
@@ -1,14 +1,15 @@
 read_verilog -icells <<EOT
 
-module top(input C, D, S, R, output [9:0] Q);
+module top(input C, D, E, S, R, output [11:0] Q);
 
 $_DFF_P_ ff0 (.C(C), .D(D), .Q(Q[0]));
 $_DFF_PP0_ ff1 (.C(C), .D(D), .R(R), .Q(Q[1]));
 $_DFF_PP1_ ff2 (.C(C), .D(D), .R(R), .Q(Q[2]));
 $_DFFSR_PPP_ ff3 (.C(C), .D(D), .R(R), .S(S), .Q(Q[3]));
 $_DFFSR_NNN_ ff4 (.C(C), .D(D), .R(R), .S(S), .Q(Q[4]));
+$_DFFE_PP_ ff5 (.C(C), .D(D), .E(E), .Q(Q[5]));
 
-assign Q[9:5] = ~Q[4:0];
+assign Q[11:6] = ~Q[5:0];
 
 endmodule
 
@@ -29,23 +30,25 @@ design -load orig
 dfflibmap -liberty dfflibmap.lib
 clean
 
-select -assert-count 4 t:$_NOT_
+select -assert-count 5 t:$_NOT_
 select -assert-count 1 t:dffn
 select -assert-count 4 t:dffsr
-select -assert-none t:dffn t:dffsr t:$_NOT_ %% %n t:* %i
+select -assert-count 1 t:dffe
+select -assert-none t:dffn t:dffsr t:dffe t:$_NOT_ %% %n t:* %i
 
 design -load orig
 dfflibmap -prepare -liberty dfflibmap.lib
 
-select -assert-count 9 t:$_NOT_
+select -assert-count 11 t:$_NOT_
 select -assert-count 1 t:$_DFF_N_
 select -assert-count 4 t:$_DFFSR_PPP_
-select -assert-none t:$_DFF_N_ t:$_DFFSR_PPP_ t:$_NOT_ %% %n t:* %i
+select -assert-count 1 t:$_DFFE_NP_
+select -assert-none t:$_DFF_N_ t:$_DFFSR_PPP_ t:$_DFFE_NP_ t:$_NOT_ %% %n t:* %i
 
 design -load orig
 dfflibmap -map-only -liberty dfflibmap.lib
 
-select -assert-count 5 t:$_NOT_
+select -assert-count 6 t:$_NOT_
 select -assert-count 0 t:dffn
 select -assert-count 1 t:dffsr
 
@@ -54,10 +57,11 @@ dfflibmap -prepare -liberty dfflibmap.lib
 dfflibmap -map-only -liberty dfflibmap.lib
 clean
 
-select -assert-count 4 t:$_NOT_
+select -assert-count 5 t:$_NOT_
 select -assert-count 1 t:dffn
 select -assert-count 4 t:dffsr
-select -assert-none t:dffn t:dffsr t:$_NOT_ %% %n t:* %i
+select -assert-count 1 t:dffe
+select -assert-none t:dffn t:dffsr t:dffe t:$_NOT_ %% %n t:* %i
 
 design -load orig
 dfflibmap -liberty dfflibmap.lib -dont_use *ffn
@@ -65,3 +69,4 @@ clean
 
 select -assert-count 0 t:dffn
 select -assert-count 5 t:dffsr
+select -assert-count 1 t:dffe