[flang-commits] [flang] [flang][OpenMP] Generalize checks of loop construct structure (PR #170735)

[Michael Kruse via flang-commits]

================
@@ -262,41 +270,106 @@ static bool IsLoopTransforming(llvm::omp::Directive dir) {
   }
 }
 
-void OmpStructureChecker::CheckNestedBlock(const parser::OpenMPLoopConstruct &x,
-    const parser::Block &body, size_t &nestedCount) {
+void OmpStructureChecker::CheckNestedBlock(
+    const parser::OpenMPLoopConstruct &x, const parser::Block &body) {
   for (auto &stmt : body) {
     if (auto *dir{parser::Unwrap<parser::CompilerDirective>(stmt)}) {
       context_.Say(dir->source,
           "Compiler directives are not allowed inside OpenMP loop constructs"_warn_en_US);
-    } else if (parser::Unwrap<parser::DoConstruct>(stmt)) {
-      ++nestedCount;
     } else if (auto *omp{parser::Unwrap<parser::OpenMPLoopConstruct>(stmt)}) {
       if (!IsLoopTransforming(omp->BeginDir().DirId())) {
         context_.Say(omp->source,
             "Only loop-transforming OpenMP constructs are allowed inside OpenMP loop constructs"_err_en_US);
       }
-      ++nestedCount;
     } else if (auto *block{parser::Unwrap<parser::BlockConstruct>(stmt)}) {
-      CheckNestedBlock(x, std::get<parser::Block>(block->t), nestedCount);
-    } else {
+      CheckNestedBlock(x, std::get<parser::Block>(block->t));
+    } else if (!parser::Unwrap<parser::DoConstruct>(stmt)) {
       parser::CharBlock source{parser::GetSource(stmt).value_or(x.source)};
       context_.Say(source,
           "OpenMP loop construct can only contain DO loops or loop-nest-generating OpenMP constructs"_err_en_US);
     }
   }
 }
 
+static bool IsFullUnroll(const parser::OpenMPLoopConstruct &x) {
+  const parser::OmpDirectiveSpecification &beginSpec{x.BeginDir()};
+
+  if (beginSpec.DirName().v == llvm::omp::Directive::OMPD_unroll) {
+    return llvm::none_of(beginSpec.Clauses().v, [](const parser::OmpClause &c) {
+      return c.Id() == llvm::omp::Clause::OMPC_partial;
+    });
+  }
+  return false;
+}
+
+static std::optional<size_t> CountGeneratedLoops(
----------------
Meinersbur wrote:

Sorry for the late review. PR looks good, just a terminology note:

To distingish from loops nested inside each other in a loop nest, the OpenMP spec uses "loop nests" to describe the elements of a loop (nest) sequence. With the `depth` clause, the `fuse` construct can also entire loops nests, e.g.

```f90
!$OMP FUSE DEPTH(2)
  DO I1 = 1, 10
    DO J1 = 1, 10
    END DO
  END DO
  DO I2 = 1, 10
    DO J2 = 1, 10
    END DO
  END DO
!$OMP END FUSE
```
So I think the name `GeneratedLoops` is ambiguous here.

https://github.com/llvm/llvm-project/pull/170735