[flang-commits] [clang] [flang] [flang][OpenMP] Upstream first part of `do concurrent` mapping (PR #126026)

[Kiran Chandramohan via flang-commits]

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@@ -352,16 +352,38 @@ bool CodeGenAction::beginSourceFileAction() {
   // Add OpenMP-related passes
   // WARNING: These passes must be run immediately after the lowering to ensure
   // that the FIR is correct with respect to OpenMP operations/attributes.
-  if (ci.getInvocation().getFrontendOpts().features.IsEnabled(
-          Fortran::common::LanguageFeature::OpenMP)) {
-    bool isDevice = false;
+  bool isOpenMPEnabled =
+      ci.getInvocation().getFrontendOpts().features.IsEnabled(
+          Fortran::common::LanguageFeature::OpenMP);
+
+  fir::OpenMPFIRPassPipelineOpts opts;
+
+  using DoConcurrentMappingKind =
+      Fortran::frontend::CodeGenOptions::DoConcurrentMappingKind;
+  opts.doConcurrentMappingKind =
+      ci.getInvocation().getCodeGenOpts().getDoConcurrentMapping();
+
+  if (opts.doConcurrentMappingKind != DoConcurrentMappingKind::DCMK_None &&
+      !isOpenMPEnabled) {
+    unsigned diagID = ci.getDiagnostics().getCustomDiagID(
+        clang::DiagnosticsEngine::Warning,
+        "lowering `do concurrent` loops to OpenMP is only supported if "
+        "OpenMP is enabled. Enable OpenMP using `-fopenmp`. `do concurrent` "
+        "loops will be serialized.");
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kiranchandramohan wrote:

Nit: It will be great if the warning can be in a single line or in lines separated by full stops. This will aid better searching for this warning.

https://github.com/llvm/llvm-project/pull/126026