Synth commands

Packaged synth_* commands

The following is a list of all synth commands included in Yosys for different platforms. Each command runs a script of sub commands specific to the platform being targeted. Note that not all of these scripts are actively maintained and may not be up-to-date.

• synth_achronix - synthesis for Achronix Speedster22i FPGAs.

• synth_anlogic - synthesis for Anlogic FPGAs

• synth_coolrunner2 - synthesis for Xilinx Coolrunner-II CPLDs

• synth_easic - synthesis for eASIC platform

• synth_ecp5 - synthesis for ECP5 FPGAs

• synth_efinix - synthesis for Efinix FPGAs

• synth_fabulous - FABulous synthesis script

• synth_gatemate - synthesis for Cologne Chip GateMate FPGAs

• synth_gowin - synthesis for Gowin FPGAs

• synth_greenpak4 - synthesis for GreenPAK4 FPGAs

• synth_ice40 - synthesis for iCE40 FPGAs

• synth_intel - synthesis for Intel (Altera) FPGAs. (MAX10, Cyclone IV)

• synth_intel_alm - synthesis for ALM-based Intel (Altera) FPGAs. (Cyclone V, Arria V, Cyclone 10 GX)

• synth_lattice - synthesis for Lattice FPGAs

• synth_nexus - synthesis for Lattice Nexus FPGAs

• synth_quicklogic - Synthesis for QuickLogic FPGAs

• synth_sf2 - synthesis for SmartFusion2 and IGLOO2 FPGAs

• synth_xilinx - synthesis for Xilinx FPGAs

General synthesis

In addition to the above hardware-specific synth commands, there is also prep - generic synthesis script. This command is limited to coarse-grain synthesis, without getting into any architecture-specific mappings or optimizations. Among other things, this is useful for design verification.

The following commands are executed by the prep command:

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

coarse:
    proc [-ifx]
    flatten    (if -flatten)
    future
    opt_expr -keepdc
    opt_clean
    check
    opt -noff -keepdc
    wreduce -keepdc [-memx]
    memory_dff    (if -rdff)
    memory_memx    (if -memx)
    opt_clean
    memory_collect
    opt -noff -keepdc -fast

check:
    stat
    check

Synthesis starter covers most of these commands and what they do.