From 5b999ae68decef5646ef0ccac53463f22fe18d8f Mon Sep 17 00:00:00 2001
From: Eddie Hung <eddie@fpgeh.com>
Date: Mon, 10 Jun 2019 10:32:19 -0700
Subject: [PATCH] Elaborate muxpack doc
---
passes/opt/muxpack.cc | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/passes/opt/muxpack.cc b/passes/opt/muxpack.cc
index f01d5474d..b6f3313bf 100644
--- a/passes/opt/muxpack.cc
+++ b/passes/opt/muxpack.cc
@@ -302,8 +302,12 @@ struct MuxpackPass : public Pass {
log(" muxpack [selection]\n");
log("\n");
log("This pass converts cascaded chains of $pmux cells (e.g. those create from case\n");
- log("constructs) and $mux cells (e.g. those created by if-else constructs) into \n");
- log("into $pmux cells.\n");
+ log("constructs) and $mux cells (e.g. those created by if-else constructs) into\n");
+ log("$pmux cells.\n");
+ log("\n");
+ log("This optimisation is conservative --- it will only pack $mux or $pmux cells with\n");
+ log("other such cells if it can be certain that the select lines are mutually\n");
+ log("exclusive.\n");
log("\n");
}
void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE