This patch introduces V3HashTable.h, which defines an open addressing,
linear probing hash table. The table implement the public V3HashSet and
V3HashMap templates, which are generic containers. The benefit of this
over std::unordered_map and std::unordered_set is far better memory
locality during lookup. (The STL containers use chaining and require a
new heap allocation for every insertion, similarly probing involves
pointer chasing on collisions).
The new data structure is use in V3DfgCache, and V3DfgCse and yields a
significant speed improvement of those passes on large designs.
Each VCMethod now carries a signature describing the access required of
the references passed as arguments to the call. 'r' if the argument is
read, 'w' if it is fully assigned so the old value does not matter, 'm'
if it is modified (or only conditionally assigned), with a trailing '+'
repeating the preceding entry for all remaining arguments. Signatures
are validated at compile time, and V3Broken checks the arguments of
every AstCMethodHard against them.
The incorrect references this found and that are easy to fix are
repaired in this patch. "TODO" marks method that are currently broken or
not yet fit the scheme, these will be fixed in follow up patches.
Also renames SCHED_COMMIT and SCHED_ENQUEUE to NBA_COMMIT and
NBA_ENQUEUE, and remove unused methods.
The loops modelling the SystemVerilog scheduling regions are no longer
generated. They now live in 'VerilatedEvalLoop' in the runtime library.
The generated model holds one as a member, passing itself to it, and
exposes each evaluation entry point to it as a pure virtual method on
VerilatedModel. The model's 'eval' and 'eval_step' remain the top level
entry points, and are backward compatible.
V3Sched no longer emits '_eval' or '_eval_settle', etc.. Instead every
evaluation entry point called from the runtime is enumerated by 'VEval',
Scheduling creates all entry points, for all scheduling regions, even if
they are empty, and the runtime eval loop calls everything
unconditionally. If regions are empty, this is simply a call to an empty
function. This will hurt performance on very small models, but should
not be noticeable on anything meaningful, so it is likely best to keep
to reduce complexity.
A scheduling entry points evaluate a single iteration and returns
whether it did any work, they are effectively the previous
`_eval_phase_*` functions.
Todd Strader
Nick Brereton
Geza Lore
Matthew Ballance
Marco Frank
Marco Bartoli
Kamil Danecki
Sumanth KadiyalaandSumanth Kadiyala
Aditya Shevade
Wilson Snyder
Szymon Gizler
Paul Rigge
Jakub Wasilewski
Aliaksei Chapyzhenka
Yilou Wang
Andrii
Kornel Uriasz
Sunimali Rathnayake
Demin Han
Adam Kostrzewski
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Bartłomiej Chmiel
Tyrone Marhguy
BRDR LIFE
Artur Bieniek
24bit-xjkp
Bartosz Skorowski
Jeffrey Song