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example_synth: proc and opt_expr

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Highlight `proc` blocks and intro `opt_expr`.
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Krystine Sherwin 2024-01-16 13:23:04 +13:00
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97
docs/source/code_examples/fifo/fifo.out
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@ -29,13 +29,13 @@ Removed 2 unused modules.
yosys> select -set new_cells t:*
yosys> show -color maroon3 @new_cells -notitle -format dot -prefix addr_gen_hier
yosys> show -color maroon3 @new_cells -color cornflowerblue p:* -notitle -format dot -prefix addr_gen_hier
4. Generating Graphviz representation of design.
Writing dot description to `addr_gen_hier.dot'.
Dumping module addr_gen to page 1.
yosys> proc
yosys> proc -noopt
5. Executing PROC pass (convert processes to netlists).
@ -102,11 +102,6 @@ Found and cleaned up 2 empty switches in `\addr_gen.$proc$fifo.v:13$1'.
Removing empty process `addr_gen.$proc$fifo.v:13$1'.
Cleaned up 2 empty switches.
yosys> opt_expr -keepdc
5.12. Executing OPT_EXPR pass (perform const folding).
Optimizing module addr_gen.
yosys> select -set new_cells t:$mux t:*dff
yosys> show -color maroon3 @new_cells -notitle -format dot -prefix addr_gen_proc
@ -115,12 +110,19 @@ yosys> show -color maroon3 @new_cells -notitle -format dot -prefix addr_gen_proc
Writing dot description to `addr_gen_proc.dot'.
Dumping module addr_gen to page 1.
yosys> opt_expr
7. Executing OPT_EXPR pass (perform const folding).
Optimizing module addr_gen.
yosys> clean
Removed 0 unused cells and 4 unused wires.
yosys> show -notitle -format dot -prefix addr_gen_clean
yosys> select -set new_cells t:$eq
7. Generating Graphviz representation of design.
yosys> show -color cornflowerblue @new_cells -notitle -format dot -prefix addr_gen_clean
8. Generating Graphviz representation of design.
Writing dot description to `addr_gen_clean.dot'.
Dumping module addr_gen to page 1.
@ -128,7 +130,7 @@ yosys> design -reset
yosys> read_verilog fifo.v
8. Executing Verilog-2005 frontend: fifo.v
9. Executing Verilog-2005 frontend: fifo.v
Parsing Verilog input from `fifo.v' to AST representation.
Generating RTLIL representation for module `\addr_gen'.
Generating RTLIL representation for module `\fifo'.
@ -136,24 +138,24 @@ Successfully finished Verilog frontend.
yosys> hierarchy -check -top fifo
9. Executing HIERARCHY pass (managing design hierarchy).
10. Executing HIERARCHY pass (managing design hierarchy).
9.1. Analyzing design hierarchy..
10.1. Analyzing design hierarchy..
Top module: \fifo
Used module: \addr_gen
Parameter \MAX_DATA = 256
9.2. Executing AST frontend in derive mode using pre-parsed AST for module `\addr_gen'.
10.2. Executing AST frontend in derive mode using pre-parsed AST for module `\addr_gen'.
Parameter \MAX_DATA = 256
Generating RTLIL representation for module `$paramod\addr_gen\MAX_DATA=s32'00000000000000000000000100000000'.
Parameter \MAX_DATA = 256
Found cached RTLIL representation for module `$paramod\addr_gen\MAX_DATA=s32'00000000000000000000000100000000'.
9.3. Analyzing design hierarchy..
10.3. Analyzing design hierarchy..
Top module: \fifo
Used module: $paramod\addr_gen\MAX_DATA=s32'00000000000000000000000100000000
9.4. Analyzing design hierarchy..
10.4. Analyzing design hierarchy..
Top module: \fifo
Used module: $paramod\addr_gen\MAX_DATA=s32'00000000000000000000000100000000
Removing unused module `\addr_gen'.
@ -161,16 +163,16 @@ Removed 1 unused modules.
yosys> proc
10. Executing PROC pass (convert processes to netlists).
11. Executing PROC pass (convert processes to netlists).
yosys> proc_clean
10.1. Executing PROC_CLEAN pass (remove empty switches from decision trees).
11.1. Executing PROC_CLEAN pass (remove empty switches from decision trees).
Cleaned up 0 empty switches.
yosys> proc_rmdead
10.2. Executing PROC_RMDEAD pass (remove dead branches from decision trees).
11.2. Executing PROC_RMDEAD pass (remove dead branches from decision trees).
Marked 2 switch rules as full_case in process $proc$fifo.v:64$24 in module fifo.
Marked 1 switch rules as full_case in process $proc$fifo.v:38$16 in module fifo.
Marked 2 switch rules as full_case in process $proc$fifo.v:13$32 in module $paramod\addr_gen\MAX_DATA=s32'00000000000000000000000100000000.
@ -178,13 +180,13 @@ Removed a total of 0 dead cases.
yosys> proc_prune
10.3. Executing PROC_PRUNE pass (remove redundant assignments in processes).
11.3. Executing PROC_PRUNE pass (remove redundant assignments in processes).
Removed 0 redundant assignments.
Promoted 6 assignments to connections.
yosys> proc_init
10.4. Executing PROC_INIT pass (extract init attributes).
11.4. Executing PROC_INIT pass (extract init attributes).
Found init rule in `\fifo.$proc$fifo.v:0$31'.
Set init value: \count = 9'000000000
Found init rule in `$paramod\addr_gen\MAX_DATA=s32'00000000000000000000000100000000.$proc$fifo.v:0$35'.
@ -192,19 +194,19 @@ Found init rule in `$paramod\addr_gen\MAX_DATA=s32'00000000000000000000000100000
yosys> proc_arst
10.5. Executing PROC_ARST pass (detect async resets in processes).
11.5. Executing PROC_ARST pass (detect async resets in processes).
Found async reset \rst in `\fifo.$proc$fifo.v:64$24'.
Found async reset \rst in `$paramod\addr_gen\MAX_DATA=s32'00000000000000000000000100000000.$proc$fifo.v:13$32'.
yosys> proc_rom
10.6. Executing PROC_ROM pass (convert switches to ROMs).
11.6. Executing PROC_ROM pass (convert switches to ROMs).
Converted 0 switches.
<suppressed ~5 debug messages>
yosys> proc_mux
10.7. Executing PROC_MUX pass (convert decision trees to multiplexers).
11.7. Executing PROC_MUX pass (convert decision trees to multiplexers).
Creating decoders for process `\fifo.$proc$fifo.v:0$31'.
Creating decoders for process `\fifo.$proc$fifo.v:64$24'.
1/1: $0\count[8:0]
@ -218,11 +220,11 @@ Creating decoders for process `$paramod\addr_gen\MAX_DATA=s32'000000000000000000
yosys> proc_dlatch
10.8. Executing PROC_DLATCH pass (convert process syncs to latches).
11.8. Executing PROC_DLATCH pass (convert process syncs to latches).
yosys> proc_dff
10.9. Executing PROC_DFF pass (convert process syncs to FFs).
11.9. Executing PROC_DFF pass (convert process syncs to FFs).
Creating register for signal `\fifo.\count' using process `\fifo.$proc$fifo.v:64$24'.
created $adff cell `$procdff$55' with positive edge clock and positive level reset.
Creating register for signal `\fifo.\rdata' using process `\fifo.$proc$fifo.v:38$16'.
@ -238,11 +240,11 @@ Creating register for signal `$paramod\addr_gen\MAX_DATA=s32'0000000000000000000
yosys> proc_memwr
10.10. Executing PROC_MEMWR pass (convert process memory writes to cells).
11.10. Executing PROC_MEMWR pass (convert process memory writes to cells).
yosys> proc_clean
10.11. Executing PROC_CLEAN pass (remove empty switches from decision trees).
11.11. Executing PROC_CLEAN pass (remove empty switches from decision trees).
Removing empty process `fifo.$proc$fifo.v:0$31'.
Found and cleaned up 2 empty switches in `\fifo.$proc$fifo.v:64$24'.
Removing empty process `fifo.$proc$fifo.v:64$24'.
@ -255,7 +257,7 @@ Cleaned up 5 empty switches.
yosys> opt_expr -keepdc
10.12. Executing OPT_EXPR pass (perform const folding).
11.12. Executing OPT_EXPR pass (perform const folding).
Optimizing module fifo.
Optimizing module $paramod\addr_gen\MAX_DATA=s32'00000000000000000000000100000000.
@ -263,13 +265,13 @@ yosys> select -set new_cells t:$memrd
yosys> show -color maroon3 c:fifo_reader -color cornflowerblue @new_cells -notitle -format dot -prefix rdata_proc o:rdata %ci*
11. Generating Graphviz representation of design.
12. Generating Graphviz representation of design.
Writing dot description to `rdata_proc.dot'.
Dumping selected parts of module fifo to page 1.
yosys> flatten
12. Executing FLATTEN pass (flatten design).
13. Executing FLATTEN pass (flatten design).
Deleting now unused module $paramod\addr_gen\MAX_DATA=s32'00000000000000000000000100000000.
<suppressed ~2 debug messages>
@ -282,13 +284,13 @@ yosys> select -set new_cells @rdata_path o:rdata %ci3 %d i:* %d
yosys> show -color maroon3 @new_cells -notitle -format dot -prefix rdata_flat @rdata_path
13. Generating Graphviz representation of design.
14. Generating Graphviz representation of design.
Writing dot description to `rdata_flat.dot'.
Dumping selected parts of module fifo to page 1.
yosys> opt_dff
14. Executing OPT_DFF pass (perform DFF optimizations).
15. Executing OPT_DFF pass (perform DFF optimizations).
Adding EN signal on $procdff$55 ($adff) from module fifo (D = $0\count[8:0], Q = \count).
Adding EN signal on $flatten\fifo_writer.$procdff$60 ($adff) from module fifo (D = $flatten\fifo_writer.$procmux$51_Y, Q = \fifo_writer.addr).
Adding EN signal on $flatten\fifo_reader.$procdff$60 ($adff) from module fifo (D = $flatten\fifo_reader.$procmux$51_Y, Q = \fifo_reader.addr).
@ -297,13 +299,13 @@ yosys> select -set new_cells t:$adffe
yosys> show -color maroon3 @new_cells -notitle -format dot -prefix rdata_adffe o:rdata %ci*
15. Generating Graphviz representation of design.
16. Generating Graphviz representation of design.
Writing dot description to `rdata_adffe.dot'.
Dumping selected parts of module fifo to page 1.
yosys> wreduce
16. Executing WREDUCE pass (reducing word size of cells).
17. Executing WREDUCE pass (reducing word size of cells).
Removed top 31 bits (of 32) from port B of cell fifo.$add$fifo.v:68$27 ($add).
Removed top 23 bits (of 32) from port Y of cell fifo.$add$fifo.v:68$27 ($add).
Removed top 31 bits (of 32) from port B of cell fifo.$sub$fifo.v:70$30 ($sub).
@ -317,26 +319,25 @@ Removed top 31 bits (of 32) from port B of cell fifo.$flatten\fifo_reader.$add$f
Removed top 24 bits (of 32) from port Y of cell fifo.$flatten\fifo_reader.$add$fifo.v:20$34 ($add).
Removed top 23 bits (of 32) from wire fifo.$add$fifo.v:68$27_Y.
Removed top 24 bits (of 32) from wire fifo.$flatten\fifo_reader.$add$fifo.v:20$34_Y.
Removed top 24 bits (of 32) from wire fifo.$flatten\fifo_writer.$add$fifo.v:20$34_Y.
yosys> select -set new_cells t:$add %co t:$add %d
yosys> show -color maroon3 @new_cells -notitle -format dot -prefix rdata_wreduce o:rdata %ci*
17. Generating Graphviz representation of design.
18. Generating Graphviz representation of design.
Writing dot description to `rdata_wreduce.dot'.
Dumping selected parts of module fifo to page 1.
yosys> opt_clean
18. Executing OPT_CLEAN pass (remove unused cells and wires).
19. Executing OPT_CLEAN pass (remove unused cells and wires).
Finding unused cells or wires in module \fifo..
Removed 0 unused cells and 5 unused wires.
Removed 0 unused cells and 4 unused wires.
<suppressed ~1 debug messages>
yosys> memory_dff
19. Executing MEMORY_DFF pass (merging $dff cells to $memrd).
20. Executing MEMORY_DFF pass (merging $dff cells to $memrd).
Checking read port `\data'[0] in module `\fifo': merging output FF to cell.
Write port 0: non-transparent.
@ -344,13 +345,13 @@ yosys> select -set new_cells t:$memrd_v2
yosys> show -color maroon3 @new_cells -notitle -format dot -prefix rdata_memrdv2 o:rdata %ci*
20. Generating Graphviz representation of design.
21. Generating Graphviz representation of design.
Writing dot description to `rdata_memrdv2.dot'.
Dumping selected parts of module fifo to page 1.
yosys> alumacc
21. Executing ALUMACC pass (create $alu and $macc cells).
22. Executing ALUMACC pass (create $alu and $macc cells).
Extracting $alu and $macc cells in module fifo:
creating $macc model for $add$fifo.v:68$27 ($add).
creating $macc model for $flatten\fifo_reader.$add$fifo.v:20$34 ($add).
@ -360,23 +361,23 @@ Extracting $alu and $macc cells in module fifo:
creating $alu model for $macc $flatten\fifo_writer.$add$fifo.v:20$34.
creating $alu model for $macc $flatten\fifo_reader.$add$fifo.v:20$34.
creating $alu model for $macc $add$fifo.v:68$27.
creating $alu cell for $add$fifo.v:68$27: $auto$alumacc.cc:485:replace_alu$79
creating $alu cell for $flatten\fifo_reader.$add$fifo.v:20$34: $auto$alumacc.cc:485:replace_alu$82
creating $alu cell for $flatten\fifo_writer.$add$fifo.v:20$34: $auto$alumacc.cc:485:replace_alu$85
creating $alu cell for $sub$fifo.v:70$30: $auto$alumacc.cc:485:replace_alu$88
creating $alu cell for $add$fifo.v:68$27: $auto$alumacc.cc:485:replace_alu$78
creating $alu cell for $flatten\fifo_reader.$add$fifo.v:20$34: $auto$alumacc.cc:485:replace_alu$81
creating $alu cell for $flatten\fifo_writer.$add$fifo.v:20$34: $auto$alumacc.cc:485:replace_alu$84
creating $alu cell for $sub$fifo.v:70$30: $auto$alumacc.cc:485:replace_alu$87
created 4 $alu and 0 $macc cells.
yosys> select -set new_cells t:$alu t:$macc
yosys> show -color maroon3 @new_cells -notitle -format dot -prefix rdata_alumacc o:rdata %ci*
22. Generating Graphviz representation of design.
23. Generating Graphviz representation of design.
Writing dot description to `rdata_alumacc.dot'.
Dumping selected parts of module fifo to page 1.
yosys> memory_collect
23. Executing MEMORY_COLLECT pass (generating $mem cells).
24. Executing MEMORY_COLLECT pass (generating $mem cells).
yosys> select -set new_cells t:$mem_v2
@ -384,6 +385,6 @@ yosys> select -set rdata_path @new_cells %ci*:-$mem_v2[WR_DATA,WR_ADDR,WR_EN] @n
yosys> show -color maroon3 @new_cells -notitle -format dot -prefix rdata_coarse @rdata_path
24. Generating Graphviz representation of design.
25. Generating Graphviz representation of design.
Writing dot description to `rdata_coarse.dot'.
Dumping selected parts of module fifo to page 1.

9
docs/source/code_examples/fifo/fifo.ys
View file

@ -10,16 +10,17 @@ read_verilog -defer fifo.v
echo on
hierarchy -top addr_gen
select -set new_cells t:*
show -color maroon3 @new_cells -notitle -format dot -prefix addr_gen_hier
show -color maroon3 @new_cells -color cornflowerblue p:* -notitle -format dot -prefix addr_gen_hier
# ========================================================
proc
proc -noopt
select -set new_cells t:$mux t:*dff
show -color maroon3 @new_cells -notitle -format dot -prefix addr_gen_proc
# ========================================================
clean
show -notitle -format dot -prefix addr_gen_clean
opt_expr; clean
select -set new_cells t:$eq
show -color cornflowerblue @new_cells -notitle -format dot -prefix addr_gen_clean
# ========================================================
design -reset

39
docs/source/getting_started/example_synth.rst
View file

@ -124,8 +124,7 @@ Our ``addr_gen`` circuit now looks like this:
``addr_gen`` module after :cmd:ref:`hierarchy`
.. todo:: how to highlight PROC blocks?
They seem to be replaced in ``show``, so the selection never matches
.. TODO:: pending https://github.com/YosysHQ/yosys/pull/4133
Simple operations like ``addr + 1`` and ``addr == MAX_DATA-1`` can be extracted
from our ``always @`` block in :ref:`addr_gen-v`. This gives us the highlighted
@ -141,13 +140,14 @@ To handle these, let us now introduce the next command: :doc:`/cmd/proc`.
modifying the design directly, it instead calls a series of other commands. In
the case of :cmd:ref:`proc`, these sub-commands work to convert the behavioral
logic of processes into multiplexers and registers. Let's see what happens when
we run it.
we run it. For now, we will call :yoscrypt:`proc -noopt` to prevent some
automatic optimizations which would normally happen.
.. figure:: /_images/code_examples/fifo/addr_gen_proc.*
:class: width-helper
:name: addr_gen_proc
``addr_gen`` module after :cmd:ref:`proc`
``addr_gen`` module after :yoscrypt:`proc -noopt`
There are now a few new cells from our ``always @``, which have been
highlighted. The ``if`` statements are now modeled with ``$mux`` cells, while
@ -166,25 +166,42 @@ Notice how in the top left of :ref:`addr_gen_proc` we have a floating wire,
generated from the initial assignment of 0 to the ``addr`` wire. However, this
initial assignment is not synthesizable, so this will need to be cleaned up
before we can generate the physical hardware. We can do this now by calling
:cmd:ref:`clean`:
:cmd:ref:`clean`. We're also going to call :cmd:ref:`opt_expr` now, which would
normally be called at the end of :cmd:ref:`proc`. We can call both commands
at the same time by separating them with a colon: :yoscrypt:`opt_expr; clean`.
.. figure:: /_images/code_examples/fifo/addr_gen_clean.*
:class: width-helper
:name: addr_gen_clean
``addr_gen`` module after :cmd:ref:`clean`
``addr_gen`` module after :yoscrypt:`opt_expr; clean`
You may also notice that the highlighted ``$eq`` cell input of ``255`` has been
converted to ``8'11111111``. Constant values are presented in the format
``<bit_width>'<bits>``, with 32-bit values instead using the decimal number.
This indicates that the constant input has been reduced from 32-bit wide to
8-bit wide. :cmd:ref:`opt_expr` performs simple expression rewriting and
constant folding, which we discuss in more detail in
:doc:`/using_yosys/synthesis/opt`.
.. TODO:: why doesn't the 32-bit value 1 get converted to 1'1?
.. note::
:doc:`/cmd/clean` can also be called with two semicolons after any command,
for example we could have called :yoscrypt:`proc;;` instead of
:yoscrypt:`proc` and then :yoscrypt:`clean`. It is generally beneficial to
run :cmd:ref:`clean` after each command as a quick way of removing
disconnected parts of the circuit which have been left over. You may notice
some scripts will end each line with ``;;``.
for example we could have called :yoscrypt:`opt_expr;;` instead of
:yoscrypt:`opt_expr; clean`. It is generally beneficial to run
:cmd:ref:`clean` after each command as a quick way of removing disconnected
parts of the circuit which have been left over. You may notice some scripts
will end each line with ``;;``.
.. todo:: consider a brief glossary for terms like adff
.. seealso:: Advanced usage docs for
- :doc:`/using_yosys/synthesis/proc`
- :doc:`/using_yosys/synthesis/opt`
The full example
^^^^^^^^^^^^^^^^