This patch should support things like
`define foo(a, b = 3, c) a+b+c
`foo(1, ,2)
which will evaluate to 1+3+2. It also spots mistakes like
`foo(1)
(the 3rd argument doesn't have a default value, so a call site is
required to set it).
Most of the patch is a simple parser for the format in preproc.cc, but
I've also taken the opportunity to wrap up the "name -> definition"
map in a type, rather than use multiple std::map's.
Since this type needs to be visible to code that touches defines, I've
pulled it (and the frontend_verilog_preproc declaration) out into a
new file at frontends/verilog/preproc.h and included that where
necessary.
Finally, the patch adds a few tests in tests/various to check that we
are parsing everything correctly.
The three parts of a based constant (size, base, digits) are now three
separate tokens, allowing the linear whitespace (including comments)
between them to be treated as normal inter-token whitespace.
- information also useful for strongly-typed enums (not implemented)
- resolves enum values in ilang part of #1594
- still need to output enums to VCD (or better yet FST) files
Before this commit, every initial assignment to a memory generated
two wires and four assigns in a process. For unknown reasons (I did
not investigate), large amounts of assigns cause quadratic slowdown
later in the AST frontend, in processAst/removeSignalFromCaseTree.
As a consequence, common and reasonable Verilog code, such as:
reg [`WIDTH:0] mem [0:`DEPTH];
integer i; initial for (i = 0; i <= `DEPTH; i++) mem[i] = 0;
took extremely long time to be processed; around 80 s for a 8-wide,
8192-deep memory.
After this commit, initial assignments where address and/or data are
constant (after `generate`) do not incur the cost of intermediate
wires; expressions like `mem[i+1]=i^(i<<1)` are considered constant.
This results in speedups of orders of magnitude for common memory
sizes; it now takes merely 0.4 s to process a 8-wide, 8192-deep
memory, and only 5.8 s to process a 8-wide, 131072-deep one.
As a bonus, this change also results in nontrivial speedups later
in the synthesis pipeline, since pass sequencing issues meant that
all of these intermediate wires were subject to transformations such
as width reduction, even though they existed solely to be constant
folded away in `memory_collect`.
Eddie Hung
Alberto Gonzalez
N. Engelhardt
Claire Wolf
Peter Crozier
Rupert Swarbrick
Miodrag Milanović
huaixv
Marcus Comstedt
jiegec
Claire Wolf
Jeff Wang
whitequark