From ca5b910296c05c95f3bc7f2d1d2b7db19d6328e2 Mon Sep 17 00:00:00 2001
From: Jannis Harder <me@jix.one>
Date: Fri, 1 Apr 2022 21:03:20 +0200
Subject: opt_merge: Add `-keepdc` option required for formal verification

The `-keepdc` option prevents merging flipflops with dont-care bits in
their initial value, as, in general, this is not a valid transform for
formal verification.

The keepdc option of `opt` is passed along to `opt_merge` now.
---
 passes/opt/opt.cc | 1 +
 1 file changed, 1 insertion(+)

(limited to 'passes/opt/opt.cc')

diff --git a/passes/opt/opt.cc b/passes/opt/opt.cc
index c3e418c07..dc88563c2 100644
--- a/passes/opt/opt.cc
+++ b/passes/opt/opt.cc
@@ -114,6 +114,7 @@ struct OptPass : public Pass {
 			if (args[argidx] == "-keepdc") {
 				opt_expr_args += " -keepdc";
 				opt_dff_args += " -keepdc";
+				opt_merge_args += " -keepdc";
 				continue;
 			}
 			if (args[argidx] == "-nodffe") {
-- 
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