[OpenACC] Implement Sema/AST for 'atomic' construct

The atomic construct is a particularly complicated one.  The directive
itself is pretty simple, it has 5 options for the 'atomic-clause'.
However, the associated statement is fairly complicated.

'read' accepts:
  v = x;
'write' accepts:
  x = expr;
'update' (or no clause) accepts:
  x++;
  x--;
  ++x;
  --x;
  x binop= expr;
  x = x binop expr;
  x = expr binop x;

'capture' accepts either a compound statement, or:
  v = x++;
  v = x--;
  v = ++x;
  v = --x;
  v = x binop= expr;
  v = x = x binop expr;
  v = x = expr binop x;

IF 'capture' has a compound statement, it accepts:
  {v = x; x binop= expr; }
  {x binop= expr; v = x; }
  {v = x; x = x binop expr; }
  {v = x; x = expr binop x; }
  {x = x binop expr ;v = x; }
  {x = expr binop x; v = x; }
  {v = x; x = expr; }
  {v = x; x++; }
  {v = x; ++x; }
  {x++; v = x; }
  {++x; v = x; }
  {v = x; x--; }
  {v = x; --x; }
  {x--; v = x; }
  {--x; v = x; }

While these are all quite complicated, there is a significant amount
of similarity between the 'capture' and 'update' lists, so this patch
reuses a lot of the same functions.

This patch implements the entirety of 'atomic', creating a new Sema file
for the sema for it, as it is fairly sizable.

1 files changed, 1 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaExceptionSpec.cpp b/clang/lib/Sema/SemaExceptionSpec.cpp
index 7b08a06..77a1bbc 100644
--- a/clang/lib/Sema/SemaExceptionSpec.cpp
+++ b/clang/lib/Sema/SemaExceptionSpec.cpp
@@ -1425,6 +1425,7 @@ CanThrowResult Sema::canThrow(const Stmt *S) {
   case Stmt::OpenACCCombinedConstructClass:
   case Stmt::OpenACCDataConstructClass:
   case Stmt::OpenACCHostDataConstructClass:
+  case Stmt::OpenACCAtomicConstructClass:
   case Stmt::AttributedStmtClass:
   case Stmt::BreakStmtClass:
   case Stmt::CapturedStmtClass: