[flang-commits] [flang] 760bba4 - [flang][OpenMP] Allow UPDATE clause to not have any arguments (#137521)

via flang-commits flang-commits at lists.llvm.org
Thu May 1 11:30:50 PDT 2025


Author: Krzysztof Parzyszek
Date: 2025-05-01T13:30:45-05:00
New Revision: 760bba4666d6cdb7b4aef3c8ce9a242f59e39216

URL: https://github.com/llvm/llvm-project/commit/760bba4666d6cdb7b4aef3c8ce9a242f59e39216
DIFF: https://github.com/llvm/llvm-project/commit/760bba4666d6cdb7b4aef3c8ce9a242f59e39216.diff

LOG: [flang][OpenMP] Allow UPDATE clause to not have any arguments (#137521)

The UPDATE clause can be specified on both ATOMIC and DEPOBJ directives.
Currently, the ATOMIC directive has its own handling of it, and the
definition of the UPDATE clause only supports its use in the DEPOBJ
directive, where it takes a dependence-type as an argument.

The UPDATE clause on the ATOMIC directive may not have any arguments.
Since the implementation of the ATOMIC construct will be modified to use
the standard handling of clauses, the definition of UPDATE should
reflect that.

Added: 
    

Modified: 
    flang/include/flang/Parser/parse-tree.h
    flang/lib/Lower/OpenMP/Clauses.cpp
    flang/lib/Parser/openmp-parsers.cpp
    flang/lib/Semantics/check-omp-structure.cpp
    llvm/include/llvm/Frontend/OpenMP/OMP.td

Removed: 
    


################################################################################
diff  --git a/flang/include/flang/Parser/parse-tree.h b/flang/include/flang/Parser/parse-tree.h
index ca8473c6f9674..e39ecc13f4eec 100644
--- a/flang/include/flang/Parser/parse-tree.h
+++ b/flang/include/flang/Parser/parse-tree.h
@@ -4501,6 +4501,11 @@ struct OmpToClause {
 
 // Ref: [5.0:254-255], [5.1:287-288], [5.2:321-322]
 //
+// In ATOMIC construct
+// update-clause ->
+//    UPDATE                                        // Since 4.5
+//
+// In DEPOBJ construct
 // update-clause ->
 //    UPDATE(dependence-type)                       // since 5.0, until 5.1
 // update-clause ->

diff  --git a/flang/lib/Lower/OpenMP/Clauses.cpp b/flang/lib/Lower/OpenMP/Clauses.cpp
index f1330b8d1909f..c258bef2e4427 100644
--- a/flang/lib/Lower/OpenMP/Clauses.cpp
+++ b/flang/lib/Lower/OpenMP/Clauses.cpp
@@ -1400,9 +1400,13 @@ Uniform make(const parser::OmpClause::Uniform &inp,
 Update make(const parser::OmpClause::Update &inp,
             semantics::SemanticsContext &semaCtx) {
   // inp.v -> parser::OmpUpdateClause
-  auto depType =
-      common::visit([](auto &&s) { return makeDepType(s); }, inp.v.u);
-  return Update{/*DependenceType=*/depType};
+  if (inp.v) {
+    return common::visit(
+        [](auto &&s) { return Update{/*DependenceType=*/makeDepType(s)}; },
+        inp.v->u);
+  } else {
+    return Update{/*DependenceType=*/std::nullopt};
+  }
 }
 
 Use make(const parser::OmpClause::Use &inp,

diff  --git a/flang/lib/Parser/openmp-parsers.cpp b/flang/lib/Parser/openmp-parsers.cpp
index e631922a354c4..bfca4e3f1730a 100644
--- a/flang/lib/Parser/openmp-parsers.cpp
+++ b/flang/lib/Parser/openmp-parsers.cpp
@@ -836,9 +836,9 @@ TYPE_PARSER(construct<OmpInitClause>(
 TYPE_PARSER(construct<OmpAlignedClause>(Parser<OmpObjectList>{},
     maybe(":" >> nonemptyList(Parser<OmpAlignedClause::Modifier>{}))))
 
-TYPE_PARSER(construct<OmpUpdateClause>(
-    construct<OmpUpdateClause>(Parser<OmpDependenceType>{}) ||
-    construct<OmpUpdateClause>(Parser<OmpTaskDependenceType>{})))
+TYPE_PARSER( //
+    construct<OmpUpdateClause>(parenthesized(Parser<OmpDependenceType>{})) ||
+    construct<OmpUpdateClause>(parenthesized(Parser<OmpTaskDependenceType>{})))
 
 TYPE_PARSER(construct<OmpOrderClause>(
     maybe(nonemptyList(Parser<OmpOrderClause::Modifier>{}) / ":"),
@@ -1079,7 +1079,7 @@ TYPE_PARSER( //
                      parenthesized(nonemptyList(name)))) ||
     "UNTIED" >> construct<OmpClause>(construct<OmpClause::Untied>()) ||
     "UPDATE" >> construct<OmpClause>(construct<OmpClause::Update>(
-                    parenthesized(Parser<OmpUpdateClause>{}))) ||
+                    maybe(Parser<OmpUpdateClause>{}))) ||
     "WHEN" >> construct<OmpClause>(construct<OmpClause::When>(
                   parenthesized(Parser<OmpWhenClause>{}))) ||
     // Cancellable constructs
@@ -1313,24 +1313,30 @@ TYPE_PARSER(
     endOfLine)
 
 // Directives enclosing structured-block
-TYPE_PARSER(construct<OmpBlockDirective>(first(
-    "MASKED" >> pure(llvm::omp::Directive::OMPD_masked),
-    "MASTER" >> pure(llvm::omp::Directive::OMPD_master),
-    "ORDERED" >> pure(llvm::omp::Directive::OMPD_ordered),
-    "PARALLEL MASKED" >> pure(llvm::omp::Directive::OMPD_parallel_masked),
-    "PARALLEL MASTER" >> pure(llvm::omp::Directive::OMPD_parallel_master),
-    "PARALLEL WORKSHARE" >> pure(llvm::omp::Directive::OMPD_parallel_workshare),
-    "PARALLEL" >> pure(llvm::omp::Directive::OMPD_parallel),
-    "SCOPE" >> pure(llvm::omp::Directive::OMPD_scope),
-    "SINGLE" >> pure(llvm::omp::Directive::OMPD_single),
-    "TARGET DATA" >> pure(llvm::omp::Directive::OMPD_target_data),
-    "TARGET PARALLEL" >> pure(llvm::omp::Directive::OMPD_target_parallel),
-    "TARGET TEAMS" >> pure(llvm::omp::Directive::OMPD_target_teams),
-    "TARGET" >> pure(llvm::omp::Directive::OMPD_target),
-    "TASK"_id >> pure(llvm::omp::Directive::OMPD_task),
-    "TASKGROUP" >> pure(llvm::omp::Directive::OMPD_taskgroup),
-    "TEAMS" >> pure(llvm::omp::Directive::OMPD_teams),
-    "WORKSHARE" >> pure(llvm::omp::Directive::OMPD_workshare))))
+TYPE_PARSER(
+    // In this context "TARGET UPDATE" can be parsed as a TARGET directive
+    // followed by an UPDATE clause. This is the only combination at the
+    // moment, exclude it explicitly.
+    (!"TARGET UPDATE"_sptok) >=
+    construct<OmpBlockDirective>(first(
+        "MASKED" >> pure(llvm::omp::Directive::OMPD_masked),
+        "MASTER" >> pure(llvm::omp::Directive::OMPD_master),
+        "ORDERED" >> pure(llvm::omp::Directive::OMPD_ordered),
+        "PARALLEL MASKED" >> pure(llvm::omp::Directive::OMPD_parallel_masked),
+        "PARALLEL MASTER" >> pure(llvm::omp::Directive::OMPD_parallel_master),
+        "PARALLEL WORKSHARE" >>
+            pure(llvm::omp::Directive::OMPD_parallel_workshare),
+        "PARALLEL" >> pure(llvm::omp::Directive::OMPD_parallel),
+        "SCOPE" >> pure(llvm::omp::Directive::OMPD_scope),
+        "SINGLE" >> pure(llvm::omp::Directive::OMPD_single),
+        "TARGET DATA" >> pure(llvm::omp::Directive::OMPD_target_data),
+        "TARGET PARALLEL" >> pure(llvm::omp::Directive::OMPD_target_parallel),
+        "TARGET TEAMS" >> pure(llvm::omp::Directive::OMPD_target_teams),
+        "TARGET" >> pure(llvm::omp::Directive::OMPD_target),
+        "TASK"_id >> pure(llvm::omp::Directive::OMPD_task),
+        "TASKGROUP" >> pure(llvm::omp::Directive::OMPD_taskgroup),
+        "TEAMS" >> pure(llvm::omp::Directive::OMPD_teams),
+        "WORKSHARE" >> pure(llvm::omp::Directive::OMPD_workshare))))
 
 TYPE_PARSER(sourced(construct<OmpBeginBlockDirective>(
     sourced(Parser<OmpBlockDirective>{}), Parser<OmpClauseList>{})))

diff  --git a/flang/lib/Semantics/check-omp-structure.cpp b/flang/lib/Semantics/check-omp-structure.cpp
index d9fe32bae1c27..f654fe6e4681a 100644
--- a/flang/lib/Semantics/check-omp-structure.cpp
+++ b/flang/lib/Semantics/check-omp-structure.cpp
@@ -4571,10 +4571,18 @@ void OmpStructureChecker::Enter(const parser::OmpClause::Update &x) {
   llvm::omp::Directive dir{GetContext().directive};
   unsigned version{context_.langOptions().OpenMPVersion};
 
-  auto *depType{std::get_if<parser::OmpDependenceType>(&x.v.u)};
-  auto *taskType{std::get_if<parser::OmpTaskDependenceType>(&x.v.u)};
-  assert(((depType == nullptr) != (taskType == nullptr)) &&
-      "Unexpected alternative in update clause");
+  const parser::OmpDependenceType *depType{nullptr};
+  const parser::OmpTaskDependenceType *taskType{nullptr};
+  if (auto &maybeUpdate{x.v}) {
+    depType = std::get_if<parser::OmpDependenceType>(&maybeUpdate->u);
+    taskType = std::get_if<parser::OmpTaskDependenceType>(&maybeUpdate->u);
+  }
+
+  if (!depType && !taskType) {
+    assert(dir == llvm::omp::Directive::OMPD_atomic &&
+        "Unexpected alternative in update clause");
+    return;
+  }
 
   if (depType) {
     CheckDependenceType(depType->v);

diff  --git a/llvm/include/llvm/Frontend/OpenMP/OMP.td b/llvm/include/llvm/Frontend/OpenMP/OMP.td
index cdfd3e3223fa8..f4e400b651c31 100644
--- a/llvm/include/llvm/Frontend/OpenMP/OMP.td
+++ b/llvm/include/llvm/Frontend/OpenMP/OMP.td
@@ -525,6 +525,7 @@ def OMPC_Untied : Clause<"untied"> {
 def OMPC_Update : Clause<"update"> {
   let clangClass = "OMPUpdateClause";
   let flangClass = "OmpUpdateClause";
+  let isValueOptional = true;
 }
 def OMPC_Use : Clause<"use"> {
   let clangClass = "OMPUseClause";


        


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