[flang][openacc][openmp] Update stride computation for bounds (#72168)

This patch updates the stride computation for the outer dimensions of
multidimensional arrays where the stride is read from the descriptor.
For the inner dimension, the stride is the element size in bytes. Then
it is multiplied by the n-1 extent for outer dimensions.

Author: clementval

flang/lib/Lower/DirectivesCommon.h

@@ -597,6 +597,7 @@ genBoundsOpsFromBox(fir::FirOpBuilder &builder, mlir::Location loc,
   mlir::Value one = builder.createIntegerConstant(loc, idxTy, 1);
   assert(box.getType().isa<fir::BaseBoxType>() &&
          "expect fir.box or fir.class");
+  mlir::Value byteStride;
   for (unsigned dim = 0; dim < dataExv.rank(); ++dim) {
     mlir::Value d = builder.createIntegerConstant(loc, idxTy, dim);
     mlir::Value baseLb =
@@ -606,9 +607,13 @@ genBoundsOpsFromBox(fir::FirOpBuilder &builder, mlir::Location loc,
     mlir::Value lb = builder.createIntegerConstant(loc, idxTy, 0);
     mlir::Value ub =
         builder.create<mlir::arith::SubIOp>(loc, dimInfo.getExtent(), one);
-    mlir::Value bound =
-        builder.create<BoundsOp>(loc, boundTy, lb, ub, mlir::Value(),
-                                 dimInfo.getByteStride(), true, baseLb);
+    if (dim == 0) // First stride is the element size.
+      byteStride = dimInfo.getByteStride();
+    mlir::Value bound = builder.create<BoundsOp>(
+        loc, boundTy, lb, ub, mlir::Value(), byteStride, true, baseLb);
+    // Compute the stride for the next dimension.
+    byteStride = builder.create<mlir::arith::MulIOp>(loc, byteStride,
+                                                     dimInfo.getExtent());
     bounds.push_back(bound);
   }
   return bounds;

flang/test/Lower/OpenACC/acc-bounds.f90

@@ -102,4 +102,26 @@ subroutine acc_undefined_extent(a)
 ! HLFIR: %[[PRESENT:.*]] = acc.present varPtr(%[[DECL_ARG0]]#1 : !fir.ref<!fir.array<?xf32>>) bounds(%[[BOUND]]) -> !fir.ref<!fir.array<?xf32>> {name = "a"}
 ! CHECK: acc.kernels dataOperands(%[[PRESENT]] : !fir.ref<!fir.array<?xf32>>)
 
+  subroutine acc_multi_strides(a)
+    real, dimension(:,:,:) :: a
+
+    !$acc kernels present(a)
+    !$acc end kernels
+  end subroutine
+
+! CHECK-LABEL: func.func @_QMopenacc_boundsPacc_multi_strides(
+! CHECK-SAME: %[[ARG0:.*]]: !fir.box<!fir.array<?x?x?xf32>> {fir.bindc_name = "a"})
+! HLFIR: %[[DECL_ARG0:.*]]:2 = hlfir.declare %[[ARG0]] {uniq_name = "_QMopenacc_boundsFacc_multi_stridesEa"} : (!fir.box<!fir.array<?x?x?xf32>>) -> (!fir.box<!fir.array<?x?x?xf32>>, !fir.box<!fir.array<?x?x?xf32>>)
+! HLFIR: %[[BOX_DIMS0:.*]]:3 = fir.box_dims %[[DECL_ARG0]]#1, %c0{{.*}} : (!fir.box<!fir.array<?x?x?xf32>>, index) -> (index, index, index)
+! HLFIR: %[[BOUNDS0:.*]] = acc.bounds lowerbound(%{{.*}} : index) upperbound(%{{.*}} : index) stride(%[[BOX_DIMS0]]#2 : index) startIdx(%{{.*}} : index) {strideInBytes = true}
+! HLFIR: %[[STRIDE1:.*]] = arith.muli %[[BOX_DIMS0]]#2, %[[BOX_DIMS0]]#1 : index
+! HLFIR: %[[BOX_DIMS1:.*]]:3 = fir.box_dims %[[DECL_ARG0]]#1, %c1{{.*}} : (!fir.box<!fir.array<?x?x?xf32>>, index) -> (index, index, index)
+! HLFIR: %[[BOUNDS1:.*]] = acc.bounds lowerbound(%{{.*}} : index) upperbound(%{{.*}} : index) stride(%[[STRIDE1]] : index) startIdx(%{{.*}} : index) {strideInBytes = true}
+! HLFIR: %[[STRIDE2:.*]] = arith.muli %[[STRIDE1]], %[[BOX_DIMS1]]#1 : index
+! HLFIR: %[[BOX_DIMS2:.*]]:3 = fir.box_dims %[[DECL_ARG0]]#1, %c2{{.*}} : (!fir.box<!fir.array<?x?x?xf32>>, index) -> (index, index, index)
+! HLFIR: %[[BOUNDS2:.*]] = acc.bounds lowerbound(%{{.*}} : index) upperbound(%{{.*}} : index) stride(%[[STRIDE2]] : index) startIdx(%{{.*}} : index) {strideInBytes = true}
+! HLFIR: %[[BOX_ADDR:.*]] = fir.box_addr %[[DECL_ARG0]]#1 : (!fir.box<!fir.array<?x?x?xf32>>) -> !fir.ref<!fir.array<?x?x?xf32>>
+! HLFIR: %[[PRESENT:.*]] = acc.present varPtr(%[[BOX_ADDR]] : !fir.ref<!fir.array<?x?x?xf32>>) bounds(%29, %33, %37) -> !fir.ref<!fir.array<?x?x?xf32>> {name = "a"}
+! HLFIR: acc.kernels dataOperands(%[[PRESENT]] : !fir.ref<!fir.array<?x?x?xf32>>) {
+
 end module