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authorLofty <dan.ravensloft@gmail.com>2023-01-25 09:26:58 +0000
committerLofty <dan.ravensloft@gmail.com>2023-01-26 05:19:45 +0000
commit822c7b0341064c3d0d9b142dc6ce61c66797159a (patch)
treeed079cb45f41e4f3615138bcd84c785dab69686f
parent2e3c08adc41a8d1cc1ac383d3b048204a691672a (diff)
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muxcover: do not add decode muxes with x inputs
-rw-r--r--passes/techmap/muxcover.cc5
-rw-r--r--tests/various/muxcover.ys40
2 files changed, 41 insertions, 4 deletions
diff --git a/passes/techmap/muxcover.cc b/passes/techmap/muxcover.cc
index a90d81985..2656f30ce 100644
--- a/passes/techmap/muxcover.cc
+++ b/passes/techmap/muxcover.cc
@@ -179,7 +179,7 @@ struct MuxcoverWorker
int prepare_decode_mux(SigBit &A, SigBit B, SigBit sel, SigBit bit)
{
- if (A == B || sel == State::Sx)
+ if (A == B || A == State::Sx || B == State::Sx || sel == State::Sx)
return 0;
tuple<SigBit, SigBit, SigBit> key(A, B, sel);
@@ -197,9 +197,6 @@ struct MuxcoverWorker
if (std::get<2>(entry))
return 0;
- if (A == State::Sx || B == State::Sx)
- return 0;
-
return cost_dmux / GetSize(std::get<1>(entry));
}
diff --git a/tests/various/muxcover.ys b/tests/various/muxcover.ys
index 67e9625e6..37a90dcb0 100644
--- a/tests/various/muxcover.ys
+++ b/tests/various/muxcover.ys
@@ -508,3 +508,43 @@ design -import gate -as gate
miter -equiv -flatten -make_assert -make_outputs -ignore_gold_x gold gate miter
sat -verify -prove-asserts -show-ports miter
+
+## implement a mux6 as a mux8 :: https://github.com/YosysHQ/yosys/issues/3591
+
+design -reset
+read_verilog << EOF
+module test (A, S, Y);
+ parameter INPUTS = 6;
+
+ input [INPUTS-1:0] A;
+ input [$clog2(INPUTS)-1:0] S;
+
+ wire [15:0] AA = {{(16-INPUTS){1'b0}}, A};
+ wire [3:0] SS = {{(4-$clog2(INPUTS)){1'b0}}, S};
+
+ output Y = SS[3] ? (SS[2] ? SS[1] ? (SS[0] ? AA[15] : AA[14])
+ : (SS[0] ? AA[13] : AA[12])
+ : SS[1] ? (SS[0] ? AA[11] : AA[10])
+ : (SS[0] ? AA[9] : AA[8]))
+ : (SS[2] ? SS[1] ? (SS[0] ? AA[7] : AA[6])
+ : (SS[0] ? AA[5] : AA[4])
+ : SS[1] ? (SS[0] ? AA[3] : AA[2])
+ : (SS[0] ? AA[1] : AA[0]));
+endmodule
+EOF
+
+prep
+design -save gold
+simplemap t:\$mux
+muxcover
+opt_clean -purge
+select -assert-count 1 t:$_MUX8_
+select -assert-none t:$_MUX8_ %% t:* %D
+techmap -map +/simcells.v t:$_MUX8_
+design -stash gate
+
+design -import gold -as gold
+design -import gate -as gate
+
+miter -equiv -flatten -make_assert -make_outputs -ignore_gold_x gold gate miter
+sat -verify -prove-asserts -show-ports miter