[flang-commits] [flang] [llvm] [flang] Support static-unit array slices in FIR LoopVersioning (PR #222723)

[Sergey Shcherbinin via flang-commits]

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@@ -260,6 +258,47 @@ static mlir::Value getLowerBound(fir::ArrayCoorOp coop, unsigned dim) {
   return {};
 }
 
+/// A fir.slice triple whose upper bound is fir.undefined selects a single
+/// element instead of a section. XArrayCoor lowering then ignores the triple's
+/// lower bound and step, and only uses the fir.array_coor index of that
+/// dimension.
+static bool isScalarSliceDim(mlir::ValueRange triples, unsigned dim) {
+  return mlir::isa_and_nonnull<fir::UndefOp>(
+      triples[3 * dim + 1].getDefiningOp());
+}
+
+/// Return the section lower bound that dimension \p dim of \p coop's slice
+/// adds to the coordinate, or a null value if it adds nothing.
+static mlir::Value getSliceLowerBound(fir::ArrayCoorOp coop, unsigned dim) {
+  if (!coop.getSlice())
+    return {};
+  auto slice = mlir::cast<fir::SliceOp>(coop.getSlice().getDefiningOp());
+  if (isScalarSliceDim(slice.getTriples(), dim))
+    return {};
+  return slice.getTriples()[3 * dim];
+}
+
+/// Match XArrayCoor's signed integerCast before computing sliced coordinates.
+/// FIR conversion zero-extends builtin i1 and unsigned integers, whereas the
+/// generic array-coordinate lowering sign-extends their bit patterns.
+static mlir::Value toSliceIndex(fir::FirOpBuilder &builder, mlir::Location loc,
+                                mlir::Value value) {
+  if (auto type = mlir::dyn_cast<mlir::IntegerType>(value.getType())) {
+    if (type.getWidth() == 1) {
+      value = builder.createConvert(loc, builder.getI1Type(), value);
+      value = mlir::arith::ExtSIOp::create(builder, loc,
+                                           builder.getIntegerType(2), value);
+    } else if (type.isUnsigned()) {
+      value = builder.createConvert(
+          loc, builder.getIntegerType(type.getWidth()), value);
+    }
+  }
+  if (value.getType().isSignlessInteger())
+    return mlir::arith::IndexCastOp::create(builder, loc,
+                                            builder.getIndexType(), value);
+  return builder.createConvert(loc, builder.getIndexType(), value);
+}
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SergeyShch01 wrote:

Thanks for pointing this out. I added this handling only to match the current XArrayCoor lowering. 



https://github.com/llvm/llvm-project/pull/222723