[OpenACC] Switch Clang to use the Flang 'appertainment' rules for clauses

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:
- [ ] Switch 'directive-kind' enum conversions to use tablegen
- [ ] Switch 'clause-kind' enum conversions to use tablegen
- [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.

Changes to Flang:
- [ ] Clang/Flang disgree on whether 'atomic' can take an 'if' clause.
This was added in OpenACC3.3_Next

Changes that need discussion/research:
- [ ] Clang/Flang disagree on whether 'init'/'shutdown' can have
multiple 'device_type' clauses. I believe there is no supporting prose
for this limitation.
- [ ] Clang/Flang disagree on whether 'init'/'shutdown' can have
multiple 'device_num' clauses.  I believe there is no supporting prose
for this limitation.,
- [ ] Clang/Flang disagree on whether 'init'/'shutdown' can have
multiple 'if' clauses. I believe there is no supporting prose for this
limitation.
- [ ]  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.
- [ ] Clang/Flang disagree on whether 'gang', 'worker', 'vector', 'seq'
may appear multiple times on a 'routine'.  Line 3080(Exactly one of the
    gang, worker, vector, or seq clauses must appear).  It is the flang
opinion that it means once-per-'device_type' (and once before each
    device_type).
- [ ] 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.
- [ ] Clang/Flang disagree whether 'loop' or combined constructs can
have 'seq', 'independent', or 'auto' with a 'device_type' clause. I see
no prose to suggest this limitation.
- [ ] 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).
- [ ] Clang/Flang disagree on clause list that may appear with a
'auto'/'independent', or 'seq' clause. for a 'loop' or 'combined'.
Flang seems to be rejecting everything, which doesn't seem correct to
me, as I can find no supporting prose. This MIGHT be a bug/difference in
implementation?
- [ ] 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-clause
basis, but doesn't do so for multiple num_gangs. ALSO: IF we decide such
a restriction means this, it needs to be applied to `kernels loop` as
well.
- [ ] Clang/Flang disagree whether 'finalize' and 'if_present' should be
allowed >1 times on a 'exit_data' construct.  I see no prose to support
this?
- [ ] Clang/Flang disagree whether 'seq' and 'self' can appear on the
same serial-loop construct.  I see no prose to support this?

Author: erichkeane

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -12929,9 +12929,6 @@ def note_acc_reduction_composite_member_loc : Note<"invalid field is here">;
 def err_acc_loop_not_for_loop
     : Error<"OpenACC '%0' construct can only be applied to a 'for' loop">;
 def note_acc_construct_here : Note<"'%0' construct is here">;
-def err_acc_loop_spec_conflict
-    : Error<"OpenACC clause '%0' on '%1' construct conflicts with previous "
-            "data dependence clause">;
 def err_acc_collapse_loop_count
     : Error<"OpenACC 'collapse' clause loop count must be a %select{constant "
             "expression|positive integer value, evaluated to %1}0">;

clang/include/clang/Sema/SemaOpenACC.h

@@ -28,6 +28,9 @@
 #include <utility>
 #include <variant>
 
+namespace {
+class SemaOpenACCClauseVisitor;
+}
 namespace clang {
 class IdentifierInfo;
 class OpenACCClause;
@@ -177,6 +180,21 @@ class SemaOpenACC : public SemaBase {
 
   void CheckLastRoutineDeclNameConflict(const NamedDecl *ND);
 
+  bool DiagnoseRequiredClauses(OpenACCDirectiveKind DK, SourceLocation DirLoc,
+                               ArrayRef<const OpenACCClause *> Clauses);
+
+  bool DiagnoseAllowedClauses(OpenACCDirectiveKind DK, OpenACCClauseKind CK,
+                              SourceLocation ClauseLoc);
+
+public:
+  // Needed from the visitor, so should be public.
+  bool DiagnoseAllowedOnceClauses(OpenACCDirectiveKind DK, OpenACCClauseKind CK,
+                                  SourceLocation ClauseLoc,
+                                  ArrayRef<const OpenACCClause *> Clauses);
+  bool DiagnoseExclusiveClauses(OpenACCDirectiveKind DK, OpenACCClauseKind CK,
+                                SourceLocation ClauseLoc,
+                                ArrayRef<const OpenACCClause *> Clauses);
+
 public:
   ComputeConstructInfo &getActiveComputeConstructInfo() {
     return ActiveComputeConstructInfo;

clang/lib/Sema/CMakeLists.txt

@@ -75,6 +75,7 @@ add_clang_library(clangSema
   SemaOpenACC.cpp
   SemaOpenACCAtomic.cpp
   SemaOpenACCClause.cpp
+  SemaOpenACCClauseAppertainment.cpp
   SemaOpenCL.cpp
   SemaOpenMP.cpp
   SemaOverload.cpp

clang/lib/Sema/SemaOpenACC.cpp

@@ -1426,30 +1426,6 @@ void SemaOpenACC::ActOnForStmtEnd(SourceLocation ForLoc, StmtResult Body) {
 }
 
 namespace {
-// Get a list of clause Kinds for diagnosing a list, joined by a commas and an
-// 'or'.
-std::string GetListOfClauses(llvm::ArrayRef<OpenACCClauseKind> Clauses) {
-  assert(!Clauses.empty() && "empty clause list not supported");
-
-  std::string Output;
-  llvm::raw_string_ostream OS{Output};
-
-  if (Clauses.size() == 1) {
-    OS << '\'' << Clauses[0] << '\'';
-    return Output;
-  }
-
-  llvm::ArrayRef<OpenACCClauseKind> AllButLast{Clauses.begin(),
-                                               Clauses.end() - 1};
-
-  llvm::interleave(
-      AllButLast, [&](OpenACCClauseKind K) { OS << '\'' << K << '\''; },
-      [&] { OS << ", "; });
-
-  OS << " or \'" << Clauses.back() << '\'';
-  return Output;
-}
-
 // Helper that should mirror ActOnRoutineName to get the FunctionDecl out for
 // magic-static checking.
 FunctionDecl *getFunctionFromRoutineName(Expr *RoutineName) {
@@ -1682,86 +1658,8 @@ bool SemaOpenACC::ActOnStartStmtDirective(
         << OpenACCClauseKind::Tile;
   }
 
-  // OpenACC3.3 2.6.5: At least one copy, copyin, copyout, create, no_create,
-  // present, deviceptr, attach, or default clause must appear on a 'data'
-  // construct.
-  if (K == OpenACCDirectiveKind::Data &&
-      llvm::find_if(Clauses,
-                    llvm::IsaPred<OpenACCCopyClause, OpenACCCopyInClause,
-                                  OpenACCCopyOutClause, OpenACCCreateClause,
-                                  OpenACCNoCreateClause, OpenACCPresentClause,
-                                  OpenACCDevicePtrClause, OpenACCAttachClause,
-                                  OpenACCDefaultClause>) == Clauses.end())
-    return Diag(StartLoc, diag::err_acc_construct_one_clause_of)
-           << K
-           << GetListOfClauses(
-                  {OpenACCClauseKind::Copy, OpenACCClauseKind::CopyIn,
-                   OpenACCClauseKind::CopyOut, OpenACCClauseKind::Create,
-                   OpenACCClauseKind::NoCreate, OpenACCClauseKind::Present,
-                   OpenACCClauseKind::DevicePtr, OpenACCClauseKind::Attach,
-                   OpenACCClauseKind::Default});
-
-  // OpenACC3.3 2.6.6: At least one copyin, create, or attach clause must appear
-  // on an enter data directive.
-  if (K == OpenACCDirectiveKind::EnterData &&
-      llvm::find_if(Clauses,
-                    llvm::IsaPred<OpenACCCopyInClause, OpenACCCreateClause,
-                                  OpenACCAttachClause>) == Clauses.end())
-    return Diag(StartLoc, diag::err_acc_construct_one_clause_of)
-           << K
-           << GetListOfClauses({
-                  OpenACCClauseKind::CopyIn,
-                  OpenACCClauseKind::Create,
-                  OpenACCClauseKind::Attach,
-              });
-  // OpenACC3.3 2.6.6: At least one copyout, delete, or detach clause must
-  // appear on an exit data directive.
-  if (K == OpenACCDirectiveKind::ExitData &&
-      llvm::find_if(Clauses,
-                    llvm::IsaPred<OpenACCCopyOutClause, OpenACCDeleteClause,
-                                  OpenACCDetachClause>) == Clauses.end())
-    return Diag(StartLoc, diag::err_acc_construct_one_clause_of)
-           << K
-           << GetListOfClauses({
-                  OpenACCClauseKind::CopyOut,
-                  OpenACCClauseKind::Delete,
-                  OpenACCClauseKind::Detach,
-              });
-
-  // OpenACC3.3 2.8: At least 'one use_device' clause must appear.
-  if (K == OpenACCDirectiveKind::HostData &&
-      llvm::find_if(Clauses, llvm::IsaPred<OpenACCUseDeviceClause>) ==
-          Clauses.end())
-    return Diag(StartLoc, diag::err_acc_construct_one_clause_of)
-           << K << GetListOfClauses({OpenACCClauseKind::UseDevice});
-
-  // OpenACC3.3 2.14.3: At least one default_async, device_num, or device_type
-  // clause must appear.
-  if (K == OpenACCDirectiveKind::Set &&
-      llvm::find_if(
-          Clauses,
-          llvm::IsaPred<OpenACCDefaultAsyncClause, OpenACCDeviceNumClause,
-                        OpenACCDeviceTypeClause, OpenACCIfClause>) ==
-          Clauses.end())
-    return Diag(StartLoc, diag::err_acc_construct_one_clause_of)
-           << K
-           << GetListOfClauses({OpenACCClauseKind::DefaultAsync,
-                                OpenACCClauseKind::DeviceNum,
-                                OpenACCClauseKind::DeviceType,
-                                OpenACCClauseKind::If});
-
-  // OpenACC3.3 2.14.4: At least one self, host, or device clause must appear on
-  // an update directive.
-  if (K == OpenACCDirectiveKind::Update &&
-      llvm::find_if(Clauses, llvm::IsaPred<OpenACCSelfClause, OpenACCHostClause,
-                                           OpenACCDeviceClause>) ==
-          Clauses.end())
-    return Diag(StartLoc, diag::err_acc_construct_one_clause_of)
-           << K
-           << GetListOfClauses({OpenACCClauseKind::Self,
-                                OpenACCClauseKind::Host,
-                                OpenACCClauseKind::Device});
-
+  if (DiagnoseRequiredClauses(K, StartLoc, Clauses))
+    return true;
   return diagnoseConstructAppertainment(*this, K, StartLoc, /*IsStmt=*/true);
 }
 
@@ -1939,19 +1837,8 @@ bool SemaOpenACC::ActOnStartDeclDirective(
   SemaRef.DiscardCleanupsInEvaluationContext();
   SemaRef.PopExpressionEvaluationContext();
 
-  if (K == OpenACCDirectiveKind::Routine &&
-      llvm::find_if(Clauses,
-                    llvm::IsaPred<OpenACCGangClause, OpenACCWorkerClause,
-                                  OpenACCVectorClause, OpenACCSeqClause>) ==
-          Clauses.end())
-    return Diag(StartLoc, diag::err_acc_construct_one_clause_of)
-           << K
-           << GetListOfClauses({
-                  OpenACCClauseKind::Gang,
-                  OpenACCClauseKind::Worker,
-                  OpenACCClauseKind::Vector,
-                  OpenACCClauseKind::Seq,
-              });
+  if (DiagnoseRequiredClauses(K, StartLoc, Clauses))
+    return true;
 
   return diagnoseConstructAppertainment(*this, K, StartLoc, /*IsStmt=*/false);
 }