[flang][openacc] Semantic checks for OpenACC 3.0 clauses validity

Summary: This patch adds semantic checking for the OpenACC 3.0 clauses validity.

Reviewers: sscalpone, tskeith, klausler, ichoyjx, DavidTruby, jdoerfert

Reviewed By: tskeith, klausler

Subscribers: mgorny, llvm-commits

Tags: #llvm, #flang

Differential Revision: https://reviews.llvm.org/D83807

Author: clementval

flang/lib/Semantics/CMakeLists.txt

@@ -2,8 +2,10 @@
 add_flang_library(FortranSemantics
   assignment.cpp
   attr.cpp
+  canonicalize-acc.cpp
   canonicalize-do.cpp
   canonicalize-omp.cpp
+  check-acc-structure.cpp
   check-allocate.cpp
   check-arithmeticif.cpp
   check-call.cpp

flang/lib/Semantics/canonicalize-acc.cpp

@@ -0,0 +1,84 @@
+//===-- lib/Semantics/canonicalize-acc.cpp --------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "canonicalize-acc.h"
+#include "flang/Parser/parse-tree-visitor.h"
+#include "flang/Semantics/tools.h"
+
+// After Loop Canonicalization, rewrite OpenACC parse tree to make OpenACC
+// Constructs more structured which provide explicit scopes for later
+// structural checks and semantic analysis.
+//   1. move structured DoConstruct into
+//      OpenACCLoopConstruct. Compilation will not proceed in case of errors
+//      after this pass.
+namespace Fortran::semantics {
+
+using namespace parser::literals;
+
+class CanonicalizationOfAcc {
+public:
+  template <typename T> bool Pre(T &) { return true; }
+  template <typename T> void Post(T &) {}
+  CanonicalizationOfAcc(parser::Messages &messages) : messages_{messages} {}
+
+  void Post(parser::Block &block) {
+    for (auto it{block.begin()}; it != block.end(); ++it) {
+      if (auto *accLoop{parser::Unwrap<parser::OpenACCLoopConstruct>(*it)}) {
+        RewriteOpenACCLoopConstruct(*accLoop, block, it);
+      }
+    } // Block list
+  }
+
+private:
+  void RewriteOpenACCLoopConstruct(parser::OpenACCLoopConstruct &x,
+      parser::Block &block, parser::Block::iterator it) {
+    // Check the sequence of DoConstruct in the same iteration
+    //
+    // Original:
+    //   ExecutableConstruct -> OpenACCConstruct -> OpenACCLoopConstruct
+    //     ACCBeginLoopDirective
+    //   ExecutableConstruct -> DoConstruct
+    //
+    // After rewriting:
+    //   ExecutableConstruct -> OpenACCConstruct -> OpenACCLoopConstruct
+    //     AccBeginLoopDirective
+    //     DoConstruct
+    parser::Block::iterator nextIt;
+    auto &beginDir{std::get<parser::AccBeginLoopDirective>(x.t)};
+    auto &dir{std::get<parser::AccLoopDirective>(beginDir.t)};
+
+    nextIt = it;
+    if (++nextIt != block.end()) {
+      if (auto *doCons{parser::Unwrap<parser::DoConstruct>(*nextIt)}) {
+        if (doCons->GetLoopControl()) {
+          // move DoConstruct
+          std::get<std::optional<parser::DoConstruct>>(x.t) =
+              std::move(*doCons);
+          nextIt = block.erase(nextIt);
+        } else {
+          messages_.Say(dir.source,
+              "DO loop after the %s directive must have loop control"_err_en_US,
+              parser::ToUpperCaseLetters(dir.source.ToString()));
+        }
+        return; // found do-loop
+      }
+    }
+    messages_.Say(dir.source,
+        "A DO loop must follow the %s directive"_err_en_US,
+        parser::ToUpperCaseLetters(dir.source.ToString()));
+  }
+
+  parser::Messages &messages_;
+};
+
+bool CanonicalizeAcc(parser::Messages &messages, parser::Program &program) {
+  CanonicalizationOfAcc acc{messages};
+  Walk(program, acc);
+  return !messages.AnyFatalError();
+}
+} // namespace Fortran::semantics

flang/lib/Semantics/canonicalize-acc.h

@@ -0,0 +1,21 @@
+//===-- lib/Semantics/canonicalize-acc.h ------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef FORTRAN_SEMANTICS_CANONICALIZE_ACC_H_
+#define FORTRAN_SEMANTICS_CANONICALIZE_ACC_H_
+
+namespace Fortran::parser {
+struct Program;
+class Messages;
+} // namespace Fortran::parser
+
+namespace Fortran::semantics {
+bool CanonicalizeAcc(parser::Messages &messages, parser::Program &program);
+}
+
+#endif // FORTRAN_SEMANTICS_CANONICALIZE_ACC_H_