I've checked these all against the Darcs history using a script
(check-copyright, in my misccode collection). Anything Neil or I did as
part of our PhDs is copyright University of Kent; more recent work
belongs to us, as appropriate.
This may seem like an odd change, but it simplifies the logic a lot. I kept having problems with passes not operating on externals (e.g. functions-to-procs, adding array sizes, constant folding in array dimensions) and adding a special case every time to also process the externals was getting silly.
Putting the externals in the AST therefore made sense, but I didn't want to just add dummy bodies as this would cause them to throw up errors (e.g. in the type-checking for functions). So I turned the bodies into a Maybe type, and that has worked out well.
I also stopped storing the formals in csExternals (since they are now in csNames, and the tree), which streamlined that nicely, and stopped me having to keep them up to date.
This fixes the AST, parser and typechecker, and adds a pass to
transform Result back into Abbrev, but doesn't transform Initial yet.
(It actually works for trivial stuff anyway, but it won't do the right
thing for complex types or PROC parameters.)
It appears (to me) to make sense to support INITIAL/RESULT reshaping
and retyping too, so this does.
Refs #42.
All the passes now have their information (name, pre-requisites and post- properties) stored at the point where the pass is declared, which means the pass lists are just a simple list of pass functions.
The main consequence of this change was that the tests had to be changed. Now, instead of taking a "pass applied to data" item (type: PassM b), they take both the pass (type: Pass) and source data (type: b), and apply them later. This was the decision that involved the simplest changes to the existing tests (simply unbracketing the application of the pass to the source). I also had to include a few old-style versions though (testPass', testPassShouldFail') for where the functions were being used to test things that weren't actually passes (mainly StructureOccam).
Fixes#48
As part of this patch, I have also introduced a helper function that fiddles the type system for those passes that must run at the top-level (i.e. on A.AST) rather than on any Data t. They will give an error if not applied at the top-level.
NameType is only really needed in the parser, so this takes it out of
NameDef, meaning that later passes defining names no longer need to
set an arbitrary NameType for them. The parser gets slightly more
complicated (because some productions now have to return a SpecType
and a NameType too), but lots of other code gets simpler.
The code that removed free names was the only thing outside the parser
using NameType, and it now makes a more sensible decision based on the
SpecType. Since unscoped names previously didn't have a SpecType at
all, I've added an Unscoped constructor to it and arranged matters
such that unscoped names now get a proper entry in csNames.
Fixes#61.
This fixes Trac ticket #46. The pass for masking out state bodies has been moved to PassList (since it's so small and should be run first) for now, and SimplifyTypes has had its previous two passes merged into one.
This fixes ticket #47 from Trac, which explains how using a dependency graph for passes was a bit too over the top, and led to unexpected results. Under the "new" (the original!) system, the pass list is used as-is, but the dependencies are checked to make sure the pass list order isn't wrong. In future we should also add back running the properties at the appropriate point (currently disabled).
Now that I have begun moving all the _sizes stuff forward into proper compiler passes, much of the code for handling arrays in the backends is going to become redundant:
- The tockArrayView class should eventually disappear; now that _sizes are pulled forward, there's no advantage of having this extra class (compared to just doing C and C++ arrays in the same, C-based, style)
- The declaration and use of the _sizes array everywhere should go, now that it is inserted in an earlier pass
I haven't removed as much as I should from the C backend; I am wary to touch it when Adam is about to move it over to the new CIF anyway
