* xilinx: eliminate SCCs from DSP48E1 model
* xilinx: add SCC test for DSP48E1
* Update techlibs/xilinx/cells_sim.v
* xilinx: Gate DSP48E1 being a whitebox behind ALLOW_WHITEBOX_DSP48E1
Have a test that checks it works through ABC9 when enabled
Quartus assumes unsigned multiplication by default, breaking signed
multiplies, so add an input signedness parameter to the MISTRAL_MUL*
cells to propagate to Quartus' <family>_mac cells.
Our techmap rules for $shift and $shiftx cells contained a special path
that aimed to decompose the shift LSB-first instead of MSB-first in
select cases that come up in pmux lowering. This path was needlessly
overcomplicated and contained bugs.
Instead of doing that, just switch over the main path to iterate
LSB-first (except for the specially-handled MSB for signed shifts
and overflow handling). This also makes the code consistent with
shl/shr/sshl/sshr cells, which are already decomposed LSB-first.
Fixes#2346.
The main part is converting ice40_dsp to recognize the new FF types
created in opt_dff instead of trying to recognize the mux patterns on
its own.
The fsm call has been moved upwards because the passes cannot deal with
$dffe/$sdff*, and other optimizations don't help it much anyway.
The main part is converting xilinx_dsp to recognize the new FF types
created in opt_dff instead of trying to recognize the patterns on its
own.
The fsm call has been moved upwards because the passes cannot deal with
$dffe/$sdff*, and other optimizations don't help it much anyway.
Of standard yosys cells, xilinx_srl only works on $_DFF_?_ and
$_DFFE_?P_, which get upgraded to $_SDFFE_?P?P_ by dfflegalize at the
point where xilinx_srl is called for non-abc9. Fix this by running
ff_map.v first, resulting in FDRE cells, which are handled correctly.
By instantiating the LUTRAM cell directly, we avoid a trip through
altsyncram, which speeds up Quartus synthesis time. This also gives
a little more flexibility, as Yosys can build RAMs out of individual
32x1 LUTRAM cells.
While working on this, I discovered that the mem_init0 parameter of
<family>_mlab_cell gets ignored by Quartus.
By operating at a layer of abstraction over the rather clumsy Intel primitives,
we can avoid special hacks like `dffinit -highlow` in favour of simple techmapping.
This also makes the primitives much easier to manipulate, and more descriptive
(no more cyclonev_lcell_comb to mean anything from a LUT2 to a LUT6).
