a2o/dev/sim/verilator/readme.md

# Verilator

##
* verilator now successfully runs, once the nclk[] changes were completed to separate clk and rst, and
remove lcb's driving lclk's

```
verilator -cc  --exe --trace --Mdir obj_dir --language 1364-2001 -Wno-fatal -Wno-LITENDIAN --error-limit 1  -Iverilog/a2o_litex -Iverilog/work -Iverilog/trilib -Iverilog/unisims a2owb.v tb_litex.cpp  |& tee verilator.txt
```

* about 5 non-scan UNOPTFLATs

## Experiments

### core-only initial experiment

```
verilator -cc --exe --trace --Mdir obj_dir --language 1364-2001 -Wno-fatal -Wno-LITENDIAN --error-limit 1 -Iverilog/work -Iverilog/trilib_clk1x -Iverilog/trilib -Iverilog/unisims c.v tb.cpp

make -C obj_dir -f Vc.mk Vc
obj_dir/Vc
```

### core + node (extmem version)

```
verilator -cc --exe --trace --Mdir obj_dir --language 1364-2001 -Wno-fatal -Wno-LITENDIAN --error-limit 1  -Iverilog/work -Iverilog/trilib_clk1x -Iverilog/trilib -Iverilog/unisims -Iverilog/a2node a2owb.v tb_node.cpp

make -C obj_dir -f Va2owb.mk Va2owb
obj_dir/Va2owb
```

* doesn't work (test3/mem.init), which does work for coccotb/icarus
* tid compare at start looks like it's using wrong value (imm from following bc?) and erat code is skipped

### core + node wb (litex)

* verilog/a2onode_litex

```
verilator -cc --exe --trace --Mdir obj_dir --language 1364-2001 -Wno-fatal -Wno-LITENDIAN --error-limit 1  -Iverilog/a2o_litex -Iverilog/work -Iverilog/trilib_clk1x -Iverilog/trilib -Iverilog/unisims a2owb.v tb_litex.cpp

make -C obj_dir -f Va2owb.mk Va2owb
obj_dir/Va2owb
```

* debugged several fails near start of test (in issues) - first few are cases of ff behaving incorrectly; syntax changes in trilib got to reaching i=1 ifetches
* added CP signals to track completions (/*verilator public*/) and now first isync fails (flushes to @04)

# Verilator Debug

##### Old Stuff

* install multiple versions concurrently

```
git pull
git checkout master
#..or...
#git checkout stable
#git checkout vxxx

unset VERILATOR_ROOT
export VERILATOR_VERSION=`git describe | sed "s/verilator_//"`
./configure --prefix /tools/verilator/$VERILATOR_VERSION
make -j <n>
make install
cp -r include /tools/verilator/$VERILATOR_VERSION   # had to do this too

# symlink
ln -sf /tools/verilator/$VERILATOR_VERSION /tools/verilator/latest
```

* pick and run...

```
export VERILATOR_ROOT=/tools/verilator/latest

# rm -r obj_dir   # to be safe?
verilator -cc --exe --trace --Mdir obj_dir --language 1364-2001 -Wno-fatal -Wno-LITENDIAN --error-limit 1  -Iverilog/a2o_litex -Iverilog/work -Iverilog/trilib_clk1x -Iverilog/trilib -Iverilog/unisims a2owb.v tb_litex.cpp

make -C obj_dir -f Va2owb.mk Va2owb
obj_dir/Va2owb
```

#### Try different versions with same RTL

* rtl and tb_litex.cpp

```
git log | head -1
commit 7cbbf9f3844a9287c5fac88867bcbcd5739914cf
```

* export VERILATOR_ROOT=/tools/verilator/v4.106
* #define OLD_PUBLIC in tb_litex.cpp

* the ifetch is bad, but so are the completes a little before it; @42C=```eratwe    r8,r0,0```

```
...

00000250 Completed: I0:1 000000000000042C
00000262 WB RD RA=00000460
00000263 WB RD ACK RA=00000460 DATA=7D4011A6
00000264 WB RD RA=00000464
00000265 WB RD ACK RA=00000464 DATA=7C8009A6
00000266 WB RD RA=00000468
00000267 WB RD ACK RA=00000468 DATA=7D0001A6
00000268 WB RD RA=0000046C
00000269 WB RD ACK RA=0000046C DATA=4C00012C
00000272 Completed: I0:1 0000000000000000 I1:1 0000000000000000
00000286 WB RD RA=00000000
*** Fetch to boot address (00000000) after initial boot! ***
```

* export VERILATOR_ROOT=/tools/verilator/v4.204

```
00000250 Completed: I0:1 000000000000042C
00000262 WB RD RA=00000460
00000263 WB RD ACK RA=00000460 DATA=7D4011A6
00000264 WB RD RA=00000464
00000265 WB RD ACK RA=00000464 DATA=7C8009A6
00000266 WB RD RA=00000468
00000267 WB RD ACK RA=00000468 DATA=7D0001A6
00000268 WB RD RA=0000046C
00000269 WB RD ACK RA=0000046C DATA=4C00012C
00000272 Completed: I0:1 0000000000000000 I1:1 0000000000000000
00000286 WB RD RA=00000000
*** Fetch to boot address (00000000) after initial boot! ***
```

* export VERILATOR_ROOT=/tools/verilator/stable  (v4.224-26-g8b7480806)

```
00000250 Completed: I0:1 000000000000042C
00000262 WB RD RA=00000460
00000263 WB RD ACK RA=00000460 DATA=7D4011A6
00000264 WB RD RA=00000464
00000265 WB RD ACK RA=00000464 DATA=7C8009A6
00000266 WB RD RA=00000468
00000267 WB RD ACK RA=00000468 DATA=7D0001A6
00000268 WB RD RA=0000046C
00000269 WB RD ACK RA=0000046C DATA=4C00012C
00000272 Completed: I0:1 0000000000000000 I1:1 0000000000000000
00000286 WB RD RA=00000000
*** Fetch to boot address (00000000) after initial boot! ***
```

* export VERILATOR_ROOT=/tools/verilator/latest  (v4.224-82-gcbe1b8e26)

```
%Error: Verilator internal fault, sorry. Suggest trying --debug --gdbbt
%Error: Command Failed /tools/verilator/latest/bin/verilator_bin -cc --exe --trace --Mdir obj_dir --language 1364-2001 -Wno-fatal -Wno-LITENDIAN --error-limit 1 -Iverilog/a2o_litex -Iverilog/work -I

verilator -cc --debug --gddbt--exe --trace --Mdir obj_dir --language 1364-2001 -Wno-fatal -Wno-LITENDIAN --error-limit 1  -Iverilog/a2o_litex -Iverilog/work -Iverilog/trilib_clk1x -Iverilog/trilib -Iverilog/unisims a2owb.v tb_litex.cpp  |& tee verilator-v224-82-debug.txt

```