Booth multiplier synthesis #3890
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What happened to this PR? |
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Hi, Matt,
I have rewritten the work as a separate pass (code attached) and will issue a new pr today for Yosys to review.
Yosys reasonably requested that no changes be made to their cell library and that the code conform to their coding coventions (so I ran it through the clang-format).
Will update you once new pr is issued. The separate pass (code attached) is a nice clean solution and lets anyone conditionally call the multpass eg:
read_verilog umultiply5_rtl.v
opt
wreduce
opt
multpass
alumacc
maccmap
opt
andy
On 09/05/2023 1:27 PM PDT Matt Liberty ***@***.***> wrote:
What happened to this PR?
—
Reply to this email directly, view it on GitHub #3890 (comment), or unsubscribe https://github.com/notifications/unsubscribe-auth/AHRTF7S4SYUZ5WZDN2EQPYDXY6DJ3ANCNFSM6AAAAAA3PS64PU.
You are receiving this because you modified the open/close state.Message ID: ***@***.***>
with kindest regards,
andy
…------------------------------------------------
Andy Fox M.Eng, PhD
US: O: 831 621 0999 M: 760 567 8391
UK: M: 0756 331 8224
https://www.linkedin.com/in/awfox/
-------------------------------------------------
laborare est orare.
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Thanks. Please @ me on the new PR so I can follow it. |
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#3924
Matt,
That pull request is just for the multiplier pass. There is a little more work to be done to make the pass be used in our (OpenRoad) flow. I have locally modified the generic synthesis command "synth" used in the open road synth.tcl to take the option -mult which forces the generic synthesis to use the multiplier pass (otherwise Yosys will smash the multipliers before we get to see them).
# Global setting for Synthesis in Makefile
export SYNTH_ARGS ?= -flatten -mult
then
in synth.tcl:
# Generic synthesis
puts "Generic synthesis"
synth -top $::env(DESIGN_NAME) {*}$::env(SYNTH_ARGS)
My plan is to review the pass with Yosys next Monday and then "negotiate" the change to their generic synthesis command synth to have a switch for the multiplier inference.
andy
PS The results with the booth still show dramatic design size reduction eg in Jpeg I see 64 booth multipliers inferred with area reduction: 96285 -> 79120
… On 09/05/2023 1:40 PM PDT Matt Liberty ***@***.***> wrote:
Thanks. Please @ me on the new PR so I can follow it.
—
Reply to this email directly, view it on GitHub #3890 (comment), or unsubscribe https://github.com/notifications/unsubscribe-auth/AHRTF7WGSIVIKDYUNOX5ZJ3XY6E37ANCNFSM6AAAAAA3PS64PU.
You are receiving this because you modified the open/close state.Message ID: ***@***.***>
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option -booth to alumacc pass to enable Booth multiplier synthesis. Improves gate count.