[flang-commits] [flang] [flang] Implement !DIR$ UNROLL [N] (PR #123331)

[Jean-Didier PAILLEUX via flang-commits]

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@@ -2153,14 +2153,42 @@ class FirConverter : public Fortran::lower::AbstractConverter {
     return builder->createIntegerConstant(loc, controlType, 1); // step
   }
 
-  void addLoopAnnotationAttr(IncrementLoopInfo &info) {
+  void addLoopAnnotationAttr(
+      IncrementLoopInfo &info,
+      llvm::SmallVectorImpl<const Fortran::parser::CompilerDirective *> &dirs) {
     mlir::BoolAttr f = mlir::BoolAttr::get(builder->getContext(), false);
-    mlir::LLVM::LoopVectorizeAttr va = mlir::LLVM::LoopVectorizeAttr::get(
-        builder->getContext(), /*disable=*/f, {}, {}, {}, {}, {}, {});
+    mlir::BoolAttr t = mlir::BoolAttr::get(builder->getContext(), true);
+    mlir::LLVM::LoopVectorizeAttr va;
+    mlir::LLVM::LoopUnrollAttr ua;
+    bool has_attrs = false;
+    for (const auto *dir : dirs) {
+      Fortran::common::visit(
+          Fortran::common::visitors{
+              [&](const Fortran::parser::CompilerDirective::VectorAlways &) {
+                va = mlir::LLVM::LoopVectorizeAttr::get(builder->getContext(),
+                                                        /*disable=*/f, {}, {},
+                                                        {}, {}, {}, {});
+                has_attrs = true;
+              },
+              [&](const Fortran::parser::CompilerDirective::Unroll &u) {
+                mlir::IntegerAttr countAttr;
+                if (u.v.has_value()) {
+                  countAttr = builder->getIntegerAttr(builder->getI64Type(),
+                                                      u.v.value());
+                }
+                ua = mlir::LLVM::LoopUnrollAttr::get(
+                    builder->getContext(), /*disable=*/f, /*count*/ countAttr,
+                    {}, /*full*/ u.v.has_value() ? f : t, {}, {}, {});
+                has_attrs = true;
+              },
+              [&](const auto &) {}},
+          dir->u);
+    }
     mlir::LLVM::LoopAnnotationAttr la = mlir::LLVM::LoopAnnotationAttr::get(
-        builder->getContext(), {}, /*vectorize=*/va, {}, {}, {}, {}, {}, {}, {},
-        {}, {}, {}, {}, {}, {});
-    info.doLoop.setLoopAnnotationAttr(la);
+        builder->getContext(), {}, /*vectorize=*/va, {}, /*unroll*/ ua, {}, {},
+        {}, {}, {}, {}, {}, {}, {}, {}, {});
+    if (has_attrs)
+      info.doLoop.setLoopAnnotationAttr(la);
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JDPailleux wrote:

Hi @DavidTruby , thanks for your feedback! About your question, I added the `has_attrs` because having moved your loop into this function, if `dirs` is empty, it will return an empty `LoopAnnotationAttr` and the attribute ` {loopAnnotation = #llvm.loop_annotation<>} ` will be put in the IR on all loops having no attached directives and many Flang tests will fail.

https://github.com/llvm/llvm-project/pull/123331