This saves about 5% memory. V3AstUserAllocator is appropriate for most use
cases, performance is marginally up as we are mostly D-cache bound on
large designs.
Apart from the representational changes below, this patch renames
AstNodeMath to AstNodeExpr, and AstCMath to AstCExpr.
Now every expression (i.e.: those AstNodes that represent a [possibly
void] value, with value being interpreted in a very general sense) has
AstNodeExpr as a super class. This necessitates the introduction of an
AstStmtExpr, which represents an expression in statement position, e.g :
'foo();' would be represented as AstStmtExpr(AstCCall(foo)). In exchange
we can get rid of isStatement() in AstNodeStmt, which now really always
represent a statement
Peak memory consumption and verilation speed are not measurably changed.
Partial step towards #3420
- Rename `--dump-treei` option to `--dumpi-tree`, which itself is now a
special case of `--dumpi-<tag>` where tag can be a magic word, or a
filename
- Control dumping via static `dump*()` functions, analogous to `debug()`
- Make dumping independent of the value of `debug()` (so dumping always
works even without the debug flag)
- Add separate `--dumpi-graph` for dumping V3Graphs, which is again a
special case of `--dumpi-<tag>`
- Alias `--dump-<tag>` to `--dumpi-<tag> 3` as before
Introduce the @astgen directives parsed by astgen, currently used for
the generation child node (operand) accessors. Please see the updated
internal documentation for details.
Introduce the @astgen directives parsed by astgen, currently used for
the generation child node (operand) accessors. Please see the updated
internal documentation for details.
The recent patch to defer substitutions on V3Gate crashes on circular
logic that has cycle length >= 3 with all inlineable signals (cycle
length 2 is detected correctly and is not inlined). Fix by stopping
recursion at the loop-back edge.
Fixes#3543
This is detritus from when V3TraceDecl used to run after V3Gate, today
V3TraceDecl runs before V3Gate and this value has no function at all.
No functional change intended.
dynamic_cast is not free. Replace obvious instances (where the result is
unconditionally dereferenced) with static_cast in contexts with
performance implications.
Adds timing support to Verilator. It makes it possible to use delays,
event controls within processes (not just at the start), wait
statements, and forks.
Building a design with those constructs requires a compiler that
supports C++20 coroutines (GCC 10, Clang 5).
The basic idea is to have processes and tasks with delays/event controls
implemented as C++20 coroutines. This allows us to suspend and resume
them at any time.
There are five main runtime classes responsible for managing suspended
coroutines:
* `VlCoroutineHandle`, a wrapper over C++20's `std::coroutine_handle`
with move semantics and automatic cleanup.
* `VlDelayScheduler`, for coroutines suspended by delays. It resumes
them at a proper simulation time.
* `VlTriggerScheduler`, for coroutines suspended by event controls. It
resumes them if its corresponding trigger was set.
* `VlForkSync`, used for syncing `fork..join` and `fork..join_any`
blocks.
* `VlCoroutine`, the return type of all verilated coroutines. It allows
for suspending a stack of coroutines (normally, C++ coroutines are
stackless).
There is a new visitor in `V3Timing.cpp` which:
* scales delays according to the timescale,
* simplifies intra-assignment timing controls and net delays into
regular timing controls and assignments,
* simplifies wait statements into loops with event controls,
* marks processes and tasks with timing controls in them as
suspendable,
* creates delay, trigger scheduler, and fork sync variables,
* transforms timing controls and fork joins into C++ awaits
There are new functions in `V3SchedTiming.cpp` (used by `V3Sched.cpp`)
that integrate static scheduling with timing. This involves providing
external domains for variables, so that the necessary combinational
logic gets triggered after coroutine resumption, as well as statements
that need to be injected into the design eval function to perform this
resumption at the correct time.
There is also a function that transforms forked processes into separate
functions.
See the comments in `verilated_timing.h`, `verilated_timing.cpp`,
`V3Timing.cpp`, and `V3SchedTiming.cpp`, as well as the internals
documentation for more details.
Signed-off-by: Krzysztof Bieganski <kbieganski@antmicro.com>
Similarly to the earlier patch that defers constant folding on optimized
logic, now we also defer the variable substitutions as well. This again
eliminates a lot of traversals, and yields another ~10x speedup of V3Gate
on a design where V3Gate used to dominate while producing identical
results.
Rather than constant folding each logic block after every substitution,
only constant fold updated blocks when re-analysed, or at the end. This
removes a lot of invocations of V3Const on large blocks that can be
optimized well, and should yield the same result.
This speeds up V3Gate by ~4x on a design where V3Gate dominates.
