Trace initialization (tracep->decl* functions) used to explicitly pass
the complete hierarchical names of signals as string constants. This
contains a lot of redundancy (path prefixes), does not scale well with
large designs and resulted in .rodata sections (the string constants) in
ELF executables being extremely large.
This patch changes the API of trace initialization that allows pushing
and popping name prefixes as we walk the hierarchy tree, which are
prepended to declared signal names at run-time during trace
initialization. This in turn allows us to emit repeat path/name
components only once, effectively removing all duplicate path prefixes.
On SweRV EH1 this reduces the .rodata section in a --trace build by 94%.
Additionally, trace declarations are now emitted in lexical order by
hierarchical signal names, and the top level trace initialization
function respects --output-split-ctrace.
The _CONST suffix on these macros is only lexical notation, pointer
constness can be preserved by overloading the underlying
implementations appropriately. Given that the compiler will catch
invalid const usage (trying to assign a non-const pointer to a const
pointer variable, etc.), and that the declarations of symbols should
make their constness obvious, I see no reason to keep the _CONST
flavours.
Fail at compile time if the result of these macros can be statically
determined (i.e.: they aways succeed or always fail). Remove unnecessary
casts discovered. No functional change.
Remove magic code fragments form EmitCTrace, so Emit need not be aware
that a function is tracing related or not (apart from the purpose of
file name generation). All necessary code is now generated via text
nodes in V3TraceDecl and V3Trace. No functional change intended.
For consistency with the rest of the generated code, generated methods
related to tracing now use snake_case instead of camelCase. No
functional change intended.
This patch introduces the concept of 'loose' methods, which semantically
are methods, but are declared as global functions, and are passed an
explicit 'self' pointer. This enables these methods to be declared
outside the class, only when they are needed, therefore removing the
header dependency. The bulk of the emitted model implementation now uses
loose methods.
The main goal of this patch is to enable splitting the full and
incremental tracing functions into multiple functions, which can then be
run in parallel at a later stage. It also simplifies further
experimentation as all of the interesting trace code construction now
happens in V3Trace. No functional change is intended by this patch, but
there are some implementation changes in the generated code.
Highlights:
- Pass symbol table directly to trace callbacks for simplicity.
- A new traceRegister function is generated which adds each trace
function as an individual callback, which means we can have multiple
callbacks for each trace function type.
- A new traceCleanup function is generated which clears the activity
flags, as the trace callbacks might be implemented as multiple functions.
- Re-worked sub-function handling so there is no separate sub-function
for each trace activity class. Sub-functions are generate when required
by splitting.
- traceFull/traceChg are now created in V3Trace rather than V3TraceDecl,
this requires carrying the trace value tree in TraceDecl until it
reaches V3Trace where the TraceInc nodes are created (previously a
TraceInc was also created in V3TraceDecl which carries the value).
* Add VL_OVERRIDE macro so that compiler can tell my typo when trying to override a function.
* Mark visit() with VL_OVERRIDE. No functional change intended.
