[clang] [llvm] Support for dispatch construct (Sema & Codegen) support. (PR #117904)

[Alexey Bataev via cfe-commits]

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@@ -5965,6 +5967,263 @@ static bool teamsLoopCanBeParallelFor(Stmt *AStmt, Sema &SemaRef) {
   return Checker.teamsLoopCanBeParallelFor();
 }
 
+static Expr *getInitialExprFromCapturedExpr(Expr *Cond) {
+
+  Expr *SubExpr = Cond->IgnoreParenImpCasts();
+
+  if (auto *DeclRef = dyn_cast<DeclRefExpr>(SubExpr)) {
+    if (auto *CapturedExprDecl =
+            dyn_cast<OMPCapturedExprDecl>(DeclRef->getDecl())) {
+
+      // Retrieve the initial expression from the captured expression
+      return CapturedExprDecl->getInit();
+    }
+  }
+  return nullptr;
+}
+
+// Next two functions, cloneAssociatedStmt() &
+// replaceWithNewTraitsOrDirectCall(), are for transforming the call traits.
+// e.g.
+// #pragma omp declare variant(foo_variant_dispatch) match(construct={dispatch})
+// #pragma omp declare variant(foo_variant_allCond) match(user={condition(1)})
+// ..
+//     #pragma omp dispatch nocontext(cond_true)
+//         foo(i, j);
+// is changed to:
+// if (cond_true) {
+//    foo(i,j) // with traits: CodeGen call to foo_variant_allCond(i,j)
+// } else {
+//   #pragma omp dispatch
+//   foo(i,j)  // with traits: CodeGen call to foo_variant_dispatch(i,j)
+// }
+//
+// The next 2 functions, are for:
+// if (cond_true) {
+//   foo(i,j) // with traits: runtime call to foo_variant_allCond(i,j)
+// }
+//
+static Expr *replaceWithNewTraitsOrDirectCall(const ASTContext &Context, Expr *,
+                                              SemaOpenMP *, bool);
+
+static StmtResult cloneAssociatedStmt(const ASTContext &Context, Stmt *StmtP,
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alexey-bataev wrote:

What does it do? Add a detailed descriptions immediately before this function. Use `///` for mat for the function documentation comments 

https://github.com/llvm/llvm-project/pull/117904