synth - generic synthesis script (original) (raw)

Back to top

View this page

Edit this page

Toggle table of contents sidebar

yosys> help synth¶

This command runs the default synthesis script. This command does not operate on partly selected designs.

use the specified module as top module (default='top')

automatically determine the top of the design hierarchy

flatten the design before synthesis. this will pass '-auto-top' to 'hierarchy' if no top module is specified.

passed to 'fsm_recode' via 'fsm'

perform synthesis for a k-LUT architecture.

do not run FSM optimization

do not run abc (as if yosys was compiled without ABC support)

run the booth pass to map $mul to Booth encoded multipliers

do not run 'alumacc' pass. i.e. keep arithmetic operators in their direct form ($add, $sub, etc.).

passed to 'memory'. prohibits merging of FFs into memory read ports

do not run SAT-based resource sharing

-run [:]

only run the commands between the labels (see below). an empty from label is synonymous to 'begin', and empty to label is synonymous to the end of the command list.

use new ABC9 flow (EXPERIMENTAL)

use FlowMap LUT techmapping instead of ABC

marks all recognized read ports as "return don't-care value on read/write collision" (same result as setting the no_rw_check attribute on all memories).

source extra rules from the given file to complement the default mapping library in the techmap step. this option can be repeated.

The following commands are executed by this synthesis command:

begin:
    hierarchy -check [-top <top> | -auto-top]

coarse:
    proc
    flatten      (if -flatten)
    opt_expr
    opt_clean
    check
    opt -nodffe -nosdff
    fsm          (unless -nofsm)
    opt
    wreduce
    peepopt
    opt_clean
    techmap -map +/cmp2lut.v -map +/cmp2lcu.v     (if -lut)
    booth        (if -booth)
    alumacc      (unless -noalumacc)
    share        (unless -noshare)
    opt
    memory -nomap
    opt_clean

fine:
    opt -fast -full
    memory_map
    opt -full
    techmap                      (unless -extra-map)
    techmap -map +/techmap.v -map <inject>      (if -extra-map)
    techmap -map +/gate2lut.v    (if -noabc and -lut)
    clean; opt_lut               (if -noabc and -lut)
    flowmap -maxlut K            (if -flowmap and -lut)
    opt -fast
    abc -fast           (unless -noabc, unless -lut)
    abc -fast -lut k    (unless -noabc, if -lut)
    opt -fast           (unless -noabc)

check:
    hierarchy -check
    stat
    check