From: Eddie Hung <eddie@fpgeh.com>
Date: Thu, 29 Aug 2019 00:07:36 +0000 (-0700)
Subject: Remove $__ICE40_FULL_ADDER handling from ice40_opt; cannot reason with
X-Git-Tag: working-ls180~1088^2~8
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=2aedee1f0e0f6a6214241f51f5c12d4b67c3ef6f;p=yosys.git

Remove $__ICE40_FULL_ADDER handling from ice40_opt; cannot reason with

CARRY_WRAPPER in the same way since I0 and I3 could be used
---

diff --git a/techlibs/ice40/ice40_opt.cc b/techlibs/ice40/ice40_opt.cc
index d5106b805..f528607d6 100644
--- a/techlibs/ice40/ice40_opt.cc
+++ b/techlibs/ice40/ice40_opt.cc
@@ -83,51 +83,6 @@ static void run_ice40_opts(Module *module)
 			}
 			continue;
 		}
-
-		if (cell->type == "$__ICE40_FULL_ADDER")
-		{
-			SigSpec non_const_inputs, replacement_output;
-			int count_zeros = 0, count_ones = 0;
-
-			SigBit inbit[3] = {
-				cell->getPort("\\A"),
-				cell->getPort("\\B"),
-				cell->getPort("\\CI")
-			};
-			for (int i = 0; i < 3; i++)
-				if (inbit[i].wire == nullptr) {
-					if (inbit[i] == State::S1)
-						count_ones++;
-					else
-						count_zeros++;
-				} else
-					non_const_inputs.append(inbit[i]);
-
-			if (count_zeros >= 2)
-				replacement_output = State::S0;
-			else if (count_ones >= 2)
-				replacement_output = State::S1;
-			else if (GetSize(non_const_inputs) == 1)
-				replacement_output = non_const_inputs;
-
-			if (GetSize(replacement_output)) {
-				optimized_co.insert(sigmap(cell->getPort("\\CO")[0]));
-				module->connect(cell->getPort("\\CO")[0], replacement_output);
-				module->design->scratchpad_set_bool("opt.did_something", true);
-				log("Optimized $__ICE40_FULL_ADDER cell back to logic (without SB_CARRY) %s.%s: CO=%s\n",
-						log_id(module), log_id(cell), log_signal(replacement_output));
-				cell->type = "$lut";
-				cell->setPort("\\A", { State::S0, inbit[0], inbit[1], inbit[2] });
-				cell->setPort("\\Y", cell->getPort("\\O"));
-				cell->unsetPort("\\B");
-				cell->unsetPort("\\CI");
-				cell->unsetPort("\\CO");
-				cell->unsetPort("\\O");
-				cell->setParam("\\LUT", RTLIL::Const::from_string("0110100110010110"));
-				cell->setParam("\\WIDTH", 4);
-			}
-			continue;
-		}
 	}
 
 	for (auto cell : sb_lut_cells)