Brought up in a previous review as a TODO, we could be better about how
we highlight what hte previous clause was, and how to show that the
'device_type' is the one being targetted. This patch rewords the
diagnostics and updates a massive number of tests.
…uses
The Flang implemenation of OpenACC uses a .td file in the llvm/Frontend
directory to determine appertainment in 4 categories:
-Required: If this list has items in it, the directive requires at least
1 of these be present.
-AllowedExclusive: Items on this list are all allowed, but only 1 from
the list may be here (That is, they are exclusive of eachother).
-AllowedOnce: Items on this list are all allowed, but may not be
duplicated.
Allowed: Items on this list are allowed. Note th at the actual list of
'allowed' is all 4 of these lists together.
This is a draft patch to swtich Clang over to use those tables. Surgery
to get this to happen in Clang Sema was somewhat reasonable. However,
some gaps in the implementations are obvious, the existing clang
implementation disagrees with the Flang interpretation of it. SO, we're
keeping a task list here based on what gets discovered.
Changes to Clang:
- [x] Switch 'directive-kind' enum conversions to use tablegen See
ff1a7bddd9435b6ae2890c07eae60bb07898bbf5
- [x] Switch 'clause-kind' enum conversions to use tablegen See
ff1a7bddd9435b6ae2890c07eae60bb07898bbf5
- [x] Investigate 'parse' test differences to see if any new
disagreements arise.
- [x] Clang/Flang disagree as to whether 'collapse' can be multiple
times on a loop. Further research showed no prose to limit this, and the
comment on the clang implementation said "no good reason to allow", so
no standards justification.
- [x] Clang/Flang disagree whether 'num_gangs' can appear >1 on a
compute/combined construct. This ended up being an unjustified
restriction.
- [x] Clang/Flang disagree as to the list of required clauses on a 'set'
construct. My research shows that Clang mistakenly included 'if' in the
list, and that it should be just 'default_async', 'device_num', and
'device_type'.
- [x] Order of 'at least one of' diagnostic has changed. Tests were
updated.
- [x] Ensure we are properly 'de-aliasing' clause names in appertainment
checks?
- [x] What is 'shortloop'? 'shortloop' seems to be an old non-standard
extension that isn't supported by flang, but is parsed for backward
compat reasons. Clang won't parse, but we at least have a spot for it in
the clause list.
- [x] Implemented proposed change for 'routine' gang/worker/vector/seq.
(see issue 539)
- [x] Implement init/shutdown can only have 1 'if' (see issue 540)
- [x] Clang/Flang disagree as to whether 'tile' is permitted more than
once on a 'loop' or combined constructs (Flang prohibits >1). I see no
justification for this in the standard. EDIT: I found a comment in clang
that I did this to make SOMETHING around duplicate checks easier.
Discussion showed we should actually have a better behavior around
'device_type' and duplicates, so I've since implemented that.
- [x] Clang/Flang disagree whether 'gang', 'worker', or 'vector' may
appear on the same construct as a 'seq' on a 'loop' or 'combined'. There
is prose for this in 2022: (a gang, worker, or vector clause may not
appear if a 'seq' clause appears). EDIT: These don't actually disagree,
but aren't in the .td file, so I restored the existing code to do this.
- [x] Clang/Flang disagree on whether 'bind' can appear >1 on a
'routine'. I believe line 3096 (A bind clause may not bind to a routine
name that has a visible bind clause) makes this limitation (Flang
permits >1 bind). we discussed and decided this should have the same
rules as worker/vector/etc, except without the 'exactly 1 of' rule (so
no dupes in individual sections).
- [x] Clang/Flang disagree on whether 'init'/'shutdown' can have
multiple 'device_num' clauses. I believe there is no supporting prose
for this limitation., We decided that `device_num` should only happen
1x.
- [x] Clang/Flang disagree whether 'num_gangs' can appear >1 on a
'kernels' construct. Line 1173 (On a kernels construct, the num_gangs
clause must have a single argument) justifies limiting on a
per-arguement basis, but doesn't do so for multiple num_gangs clauses.
WE decided to do this with the '1-per-device-type' region for num_gangs,
num_workers, and vector_length, see openacc bug here:
https://github.com/OpenACC/openacc-spec/issues/541
Changes to Flang:
- [x] Clang/Flang disgree on whether 'atomic' can take an 'if' clause.
This was added in OpenACC3.3_Next See #135451
- [x] Clang/Flang disagree on whether 'finalize' can be allowed >1 times
on a 'exit_data' construct. see #135415.
- [x] Clang/Flang disagree whether 'if_present' should be allowed >1
times on a 'host_data'/'update' construct. see #135422
- [x] Clang/Flang disagree on whether 'init'/'shutdown' can have
multiple 'device_type' clauses. I believe there is no supporting prose
for this limitation.
- [ ] SEE change for num_gangs/etc above.
Changes that need discussion/research:
Researching in prep of doing the implementation for lowering, I found
that the source of the valid identifiers list from flang is in the
frontend. This patch adds the same list to the frontend, but does it as
a sema diagnostic, so we still parse it as an identifier/identifier-like
thing, but then diagnose it as invalid later.
This is the last item of the OpenACC 3.3 spec. It includes the
implicit-name version of 'routine', plus significant refactorings to
make the two work together. The implicit name version is represented as
an attribute on the function call. This patch also implements the
clauses for the implicit-name version, as well as the A.3.4 warning.
The 'bind' clause allows the renaming of a function during code
generation. There are a few rules about when this can/cannot happen,
and it takes either a string or identifier (previously mis-implemetned
as ID-expression) argument.
Note there are additional rules to this in the implicit-function routine
case, but that isn't implemented in this patch, as implicit-function
routine is not yet implemented either.
There is a slightly different list for routine on which clauses are
permitted after it (like the rest of the constructs), but this
implements and tests them to make sure we get them right.
'nohost' is only valid on routine, and states that the compiler
shouldn't compile this routine for the host. It has no arguments, so no
checking is required besides putting it in the AST.
These 4 clauses are mutually exclusive, AND require at least one of
them. Additionally, gang has some additional restrictions in that only
the 'dim' specifier is permitted. This patch implements all of this, and
ends up refactoring the handling of each of these clauses for
readabililty.
