[flang-commits] [flang] [flang][OpenMP] Support lowering of metadirective (part 1) (PR #193664)

[Abid Qadeer via flang-commits]

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@@ -4638,11 +4586,224 @@ static void genOMP(lower::AbstractConverter &converter, lower::SymMap &symTable,
   // support the case of threadprivate variable declared in module.
 }
 
+namespace {
+struct TargetOMPContext final : public llvm::omp::OMPContext {
+  TargetOMPContext(mlir::ModuleOp module,
+                   llvm::ArrayRef<llvm::omp::TraitProperty> constructTraits)
+      // DeviceNum is set to -1 (unknown) because the
+      // target_device={device_num()} selector is not yet supported. OMPContext
+      // uses DeviceNum > -1 to activate target_device traits from the offload
+      // triple; without a concrete device number those traits are left
+      // inactive.
+      : OMPContext(isDeviceCompilation(module), fir::getTargetTriple(module),
+                   getOffloadTargetTriple(module),
+                   /*DeviceNum=*/-1),
+        targetFeatures(fir::getTargetFeatures(module)) {
+    for (llvm::omp::TraitProperty trait : constructTraits)
+      addTrait(trait);
+  }
+
+  bool matchesISATrait(llvm::StringRef rawString) const override {
+    if (!targetFeatures || targetFeatures.nullOrEmpty())
+      return false;
+    return targetFeatures.contains(("+" + rawString).str());
+  }
+
+private:
+  static bool isDeviceCompilation(mlir::ModuleOp module) {
+    return llvm::cast<mlir::omp::OffloadModuleInterface>(*module.getOperation())
+        .getIsTargetDevice();
+  }
+
+  static llvm::Triple getOffloadTargetTriple(mlir::ModuleOp module) {
+    auto offloadMod =
+        llvm::cast<mlir::omp::OffloadModuleInterface>(*module.getOperation());
+    auto targetTriples = offloadMod.getTargetTriples();
+
+    if (!targetTriples.empty())
+      if (auto tripleAttr =
+              llvm::dyn_cast<mlir::StringAttr>(targetTriples.front()))
+        return llvm::Triple(tripleAttr.getValue());
+
+    return llvm::Triple();
+  }
+
+  mlir::LLVM::TargetFeaturesAttr targetFeatures;
+};
+
+struct MetadirectiveCandidate {
+  MetadirectiveCandidate(const parser::OmpDirectiveSpecification *spec,
+                         llvm::omp::VariantMatchInfo vmi, bool isExplicit)
+      : spec(spec), vmi(vmi), isExplicit(isExplicit) {}
+
+  const parser::OmpDirectiveSpecification *spec = nullptr;
+  llvm::omp::VariantMatchInfo vmi;
+  bool isExplicit = false;
+};
+} // namespace
+
+static void appendConstructTraits(
+    mlir::Operation *op,
+    llvm::SmallVectorImpl<llvm::omp::TraitProperty> &constructTraits) {
+  if (mlir::isa<mlir::omp::SimdOp>(op))
+    constructTraits.push_back(llvm::omp::TraitProperty::construct_simd_simd);
+  if (mlir::isa<mlir::omp::WsloopOp>(op))
+    constructTraits.push_back(llvm::omp::TraitProperty::construct_for_for);
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abidh wrote:

The PR description lists construct={parallel, target, teams} as the supported construct selectors, but this code handles `SimdOp` and `WsloopOp`, covering `construct={simd}` and `construct={for}`. I don't see any tests for those two. I am also not sure how they interact with loop related constructs which are explicitly not handled by this PR. I'd suggest either removing them from this PR with a TODO comment, or adding explicit tests and updating the PR description to list them as supported.

https://github.com/llvm/llvm-project/pull/193664