Before this commit, values, wires, and memories with an initializer
were value-initialized in emitted C++ code. After this commit, all
values, wires, and memories are default-initialized, and the default
constructor of generated modules calls the reset() method, which
assigns the members that have an initializer.
Before this commit, zero width sigspecs were dumped as "" (empty
string). Unfortunately, 1364-2005 5.2.3.3 indicates that an empty
string is equivalent to "\0", and is 8 bits wide, so that's wrong.
After this commit, a replication operation with a count of zero is
used instead, which is explicitly permitted per 1364-2005 5.1.14,
and is defined to have size zero. (Its operand has to have a non-zero
size for it to be legal, though.)
PR #1203 has addressed this issue before, but in an incomplete way.
- *_en is split into *_ce (clock enable) and *_aload (async load aka
latch gate enable), so both can be present at once
- has_d is removed
- has_gclk is added (to have a clear marker for $ff)
- d_is_const and val_d leftovers are removed
- async2sync, clk2fflogic, opt_dff are updated to operate correctly on
FFs with async load
backends/protobuf/protobuf.cc depends on the source and header files
generated by protoc, but this dependency wasn't explicitly declared. Add
a rule to the Makefile to fix intermittent build failures when the
protobuf header/source file isn't built before protobuf.cc.
This mode will be used whenever read port cannot be handled in the
"extract address register" way, ie. whenever it has enable, reset,
init functionality or (in the future) mixed transparency mask.
The following VCD file crashes GTKWave's VCD loader:
$var wire 1 ! x:1 $end
$enddefinitions $end
In practice, a colon can be a part of a variable name that is
translated from a Verilog function, something like:
update$func$.../hdl/hazard3_csr.v:350$2534.$result
Public wires may alias buffered internal wires, so keep BUFFERED
wires in debug information even if they are private. Debug items are
only created for public wires, so this does not otherwise affect how
debug information is emitted.
Fixes#2540.
Fixes#2841.
While this helper is already useful to squash sequential initializations
into one in cxxrtl, its main purpose is to squash overlapping masked memory
initializations (when they land) and avoid having to deal with them in
cxxrtl runtime.
This essentially adds wide port support for free in passes that don't
have a usefully better way of handling wide ports than just breaking
them up to narrow ports, avoiding "please run memory_narrow" annoyance.
There will soon be more (versioned) memory cells, so handle passes that
only care if a cell is memory-related by a simple helper call instead of
a hardcoded list.
* xilinx: add SCC test for DSP48E1
* xilinx: Gate DSP48E1 being a whitebox behind ALLOW_WHITEBOX_DSP48E1
Have a test that checks it works through ABC9 when enabled
* abc9 to break SCCs using $__ABC9_SCC_BREAKER module
* Add test
* abc9_ops: remove refs to (* abc9_keep *) on wires
* abc9_ops: do not bypass cells in an SCC
* Add myself to CODEOWNERS for abc9*
* Fix compile
* abc9_ops: run -prep_hier before scc
* Fix tests
* Remove bug reference pending fix
* abc9: fix for -prep_hier -dff
* xaiger: restore PI handling
* abc9_ops: -prep_xaiger sigmap
* abc9_ops: -mark_scc -> -break_scc
* abc9: eliminate hard-coded abc9.box from tests
Also tidy up
* Address review
Previously, memories were silently discarded by the JSON backend, making
round-tripping modules with them crash.
Since there are already some users using JSON to implement custom
external passes that use memories (and infer width/size from memory
ports), let's fix this by just making JSON backend and frontend support
memories as first-class objects.
Processes are still not supported, and will now cause a hard error.
Fixes#1908.
Similar to the treatment of black boxes, splitting processes into two
scheduling nodes adds sufficient freedom so that netlists with
well-behaved processes (e.g. those emitted by nMigen) can immediately
converge.
Because processes are not emitted into edge-triggered regions, this
approach has comparable performance to -O5 (without -noproc), which
is substantially slower than -O6.
The exact shape of C++ code emitted by CXXRTL has a critical effect
on performance, both compile-time and runtime. CXXRTL's performance
greatly improved when it started localizing and inlining wires, not
only because this assists the optimizer and register allocator, but
also because inlining code into edge-triggered regions cuts the time
spent in eval() by at least a factor of two.
However, the logic of netlist layout has always been ad-hoc, fragile,
and very hard to understand and modify. After commit ece25a45, which
introduced outlining, the same logic started being applied to two
distinct netlists at once instead of one, which barely worked.
This commit does four major changes:
* There is now a single unambiguous source of truth (per subgraph)
for the layout of any emitted wire.
* Netlist layout is now done entirely during analysis using well
known graph algorithms; no graph operations happen when emitting.
* Netlist layout now happens completely separately for eval() and
debug_eval() subgraphs.
* Unreachable (within subgraph scope) netlist nodes are now neither
emitted nor considered for wire inlining decisions.
The netlist layout code should also now closely match the described
semantics.
As a part of this large cleanup, it includes many miscellaneous
improvements:
* The "bare minimum" debug level introduced in commit dd6a761d was
split into two levels; -g1 now emits debug information *only* for
inputs and state wires, and -g2 now emits debug information for
all public members. The old behavior matches -g2. This is done
to avoid bloat on low optimization levels.
* Debug aliases and inlined connections are now handled separately,
and complex RHS never interferes with inlined connections.
* Aliases to outlined wires now carry a pointer to the outline.
* Cell sync outputs can now be emitted in debug_eval().
* Black box debug information now includes comb/sync driver flags.
* The comment emitted for inlined cells is now accurate.
* Debug information statistics now has less noise.
* Netlist layout code is now much better documented.
Due to more precise inlining decisions, unmodified (i.e. with no
Yosys script being used) netlists now have much more logic inlined
into edge-triggered regions. On Minerva SoC SRAM, this improves
runtime by 20-25% across compilers and optimization levels.
Due to more precise reachability analysis, much less C++ code is now
emitted, especially at the maximum debug level. On Minerva SoC SRAM,
this improves clang compile time by 30-50% depending on options.
gcc is not affected.
Aki Van Ness
Jannis Harder
Miodrag Milanovic
N. Engelhardt
Claire Xenia Wolf
R
Marcelina Kościelnicka
Catherine
Lofty
the6p4c
GCHQDeveloper560
Eddie Hung
Iris Johnson
Pepijn de Vos