From 48600c77b5c989d7f305e7eadefedddd323cf566 Mon Sep 17 00:00:00 2001
From: Geza Lore <gezalore@gmail.com>
Date: Tue, 17 Jun 2025 15:53:47 +0100
Subject: [PATCH] Fix DFG binToOneHot table index missing driver (#6100)

---
 src/V3DfgPasses.cpp                    |   1 +
 test_regress/t/t_dfg_bin_to_one_hot.py |   2 +-
 test_regress/t/t_dfg_bin_to_one_hot.v  | 138 +++++++++++++++++++++++++
 3 files changed, 140 insertions(+), 1 deletion(-)

diff --git a/src/V3DfgPasses.cpp b/src/V3DfgPasses.cpp
index 6fd90bb86..1408fe40d 100644
--- a/src/V3DfgPasses.cpp
+++ b/src/V3DfgPasses.cpp
@@ -374,6 +374,7 @@ void V3DfgPasses::binToOneHot(DfgGraph& dfg, V3DfgBinToOneHotContext& ctx) {
                 const std::string name = dfg.makeUniqueName("BinToOneHot_Idx", nTables);
                 varp = dfg.makeNewVar(flp, name, idxDTypep)->as<DfgVarPacked>();
                 varp->varp()->isInternal(true);
+                varp->addDriver(flp, 0, srcp);
             }
             varp->setHasModRefs();
             return varp;
diff --git a/test_regress/t/t_dfg_bin_to_one_hot.py b/test_regress/t/t_dfg_bin_to_one_hot.py
index 1612ac838..ae6ade37b 100755
--- a/test_regress/t/t_dfg_bin_to_one_hot.py
+++ b/test_regress/t/t_dfg_bin_to_one_hot.py
@@ -16,6 +16,6 @@ test.compile(verilator_flags2=["--stats"])
 test.execute()
 
 test.file_grep(test.stats, r'Optimizations, DFG pre inline BinToOneHot, decoders created\s+(\d+)',
-               2)
+               3)
 
 test.passes()
diff --git a/test_regress/t/t_dfg_bin_to_one_hot.v b/test_regress/t/t_dfg_bin_to_one_hot.v
index 165a23f3c..2f1e3ee2b 100644
--- a/test_regress/t/t_dfg_bin_to_one_hot.v
+++ b/test_regress/t/t_dfg_bin_to_one_hot.v
@@ -162,6 +162,138 @@ module t (/*AUTOARG*/
      cntA == 7'd0
    };
 
+   // Should create decoder - with temporary needed for index variabls
+   wire [127:0] notCntAOneHot = {
+     ~cntA == 7'd127,
+     ~cntA == 7'd126,
+     ~cntA == 7'd125,
+     ~cntA == 7'd124,
+     ~cntA == 7'd123,
+     ~cntA == 7'd122,
+     ~cntA == 7'd121,
+     ~cntA == 7'd120,
+     ~cntA == 7'd119,
+     ~cntA == 7'd118,
+     ~cntA == 7'd117,
+     ~cntA == 7'd116,
+     ~cntA == 7'd115,
+     ~cntA == 7'd114,
+     ~cntA == 7'd113,
+     ~cntA == 7'd112,
+     ~cntA == 7'd111,
+     ~cntA == 7'd110,
+     ~cntA == 7'd109,
+     ~cntA == 7'd108,
+     ~cntA == 7'd107,
+     ~cntA == 7'd106,
+     ~cntA == 7'd105,
+     ~cntA == 7'd104,
+     ~cntA == 7'd103,
+     ~cntA == 7'd102,
+     ~cntA == 7'd101,
+     ~cntA == 7'd100,
+     ~cntA == 7'd99,
+     ~cntA == 7'd98,
+     ~cntA == 7'd97,
+     ~cntA == 7'd96,
+     ~cntA == 7'd95,
+     ~cntA == 7'd94,
+     ~cntA == 7'd93,
+     ~cntA == 7'd92,
+     ~cntA == 7'd91,
+     ~cntA == 7'd90,
+     ~cntA == 7'd89,
+     ~cntA == 7'd88,
+     ~cntA == 7'd87,
+     ~cntA == 7'd86,
+     ~cntA == 7'd85,
+     ~cntA == 7'd84,
+     ~cntA == 7'd83,
+     ~cntA == 7'd82,
+     ~cntA == 7'd81,
+     ~cntA == 7'd80,
+     ~cntA == 7'd79,
+     ~cntA == 7'd78,
+     ~cntA == 7'd77,
+     ~cntA == 7'd76,
+     ~cntA == 7'd75,
+     ~cntA == 7'd74,
+     ~cntA == 7'd73,
+     ~cntA == 7'd72,
+     ~cntA == 7'd71,
+     ~cntA == 7'd70,
+     ~cntA == 7'd69,
+     ~cntA == 7'd68,
+     ~cntA == 7'd67,
+     ~cntA == 7'd66,
+     ~cntA == 7'd65,
+     ~cntA == 7'd64,
+     ~cntA == 7'd63,
+     ~cntA == 7'd62,
+     ~cntA == 7'd61,
+     ~cntA == 7'd60,
+     ~cntA == 7'd59,
+     ~cntA == 7'd58,
+     ~cntA == 7'd57,
+     ~cntA == 7'd56,
+     ~cntA == 7'd55,
+     ~cntA == 7'd54,
+     ~cntA == 7'd53,
+     ~cntA == 7'd52,
+     ~cntA == 7'd51,
+     ~cntA == 7'd50,
+     ~cntA == 7'd49,
+     ~cntA == 7'd48,
+     ~cntA == 7'd47,
+     ~cntA == 7'd46,
+     ~cntA == 7'd45,
+     ~cntA == 7'd44,
+     ~cntA == 7'd43,
+     ~cntA == 7'd42,
+     ~cntA == 7'd41,
+     ~cntA == 7'd40,
+     ~cntA == 7'd39,
+     ~cntA == 7'd38,
+     ~cntA == 7'd37,
+     ~cntA == 7'd36,
+     ~cntA == 7'd35,
+     ~cntA == 7'd34,
+     ~cntA == 7'd33,
+     ~cntA == 7'd32,
+     ~cntA == 7'd31,
+     ~cntA == 7'd30,
+     ~cntA == 7'd29,
+     ~cntA == 7'd28,
+     ~cntA == 7'd27,
+     ~cntA == 7'd26,
+     ~cntA == 7'd25,
+     ~cntA == 7'd24,
+     ~cntA == 7'd23,
+     ~cntA == 7'd22,
+     ~cntA == 7'd21,
+     ~cntA == 7'd20,
+     ~cntA == 7'd19,
+     ~cntA == 7'd18,
+     ~cntA == 7'd17,
+     ~cntA == 7'd16,
+     ~cntA == 7'd15,
+     ~cntA == 7'd14,
+     ~cntA == 7'd13,
+     ~cntA == 7'd12,
+     ~cntA == 7'd11,
+     ~cntA == 7'd10,
+     ~cntA == 7'd9,
+     ~cntA == 7'd8,
+     ~cntA == 7'd7,
+     ~cntA == 7'd6,
+     ~cntA == 7'd5,
+     ~cntA == 7'd4,
+     ~cntA == 7'd3,
+     ~cntA == 7'd2,
+     ~cntA == 7'd1,
+     ~cntA == 7'd0
+   };
+
    // Should create decoder
    wire stupidWayToWriteConstOne = 1'b0
      + (cntB == 7'd127)
@@ -413,6 +545,12 @@ module t (/*AUTOARG*/
          `check(cntAOneHot[i], 1'b0);
       end
 
+      `check(notCntAOneHot[~cntA], 1'b1);
+      for (int i = 0; i < $bits(notCntAOneHot); i = i + 1) begin
+          if (i == {25'd0, ~cntA}) continue;
+         `check(notCntAOneHot[i], 1'b0);
+      end
+
       `check(stupidWayToWriteConstOne, 1'b1);
 
       `check(twiceCntC, cntC * 7'd2);