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dpiegdon / verilog-buildingblocks

Library of generic verilog buildingblocks
GNU Lesser General Public License v3.0
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Prevent Yosys from optimizing LUT4 delays #1

Closed DurandA closed 5 years ago

DurandA commented 5 years ago

Yosys recently enabled -relut by default and it is now required to add (* keep *) attributes to prevent unwanted optimizations.

See YosysHQ/yosys#1254 for more details.

dpiegdon commented 5 years ago

(doc) default-enabling of -relut enabled the opt_lut step by default. see https://github.com/YosysHQ/yosys/pull/1183/commits/b700a4b1c5dd086874c7024edb10674cf3c3a7c4

i am going to look closer into this tomorrow. thanks!

dpiegdon commented 5 years ago

ok this was more obvious than expected. thanks!