From: Eddie Hung <eddie@fpgeh.com>
Date: Wed, 7 Aug 2019 20:12:28 +0000 (-0700)
Subject: opt_lut to ignore LUT cells, or those that drive bits, with (* keep *)
X-Git-Tag: working-ls180~1159^2
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=f69410daaf68cd3cef5e365df9b27c623ce589a7;p=yosys.git

opt_lut to ignore LUT cells, or those that drive bits, with (* keep *)
---

diff --git a/passes/opt/opt_lut.cc b/passes/opt/opt_lut.cc
index 587ef878a..4c199ba72 100644
--- a/passes/opt/opt_lut.cc
+++ b/passes/opt/opt_lut.cc
@@ -101,6 +101,12 @@ struct OptLutWorker
 		{
 			if (cell->type == "$lut")
 			{
+				if (cell->has_keep_attr())
+					continue;
+				SigBit lut_output = cell->getPort("\\Y");
+				if (lut_output.wire->get_bool_attribute("\\keep"))
+					continue;
+
 				int lut_width = cell->getParam("\\WIDTH").as_int();
 				SigSpec lut_input = cell->getPort("\\A");
 				int lut_arity = 0;