Area Location Constraints - 2021.2 English

Versal ACAP AI Engine Programming Environment User Guide (UG1076)

Document ID
UG1076
ft:locale
English (United States)
Release Date
2021-12-17
Version
2021.2 English

Area location constraints direct the compiler to contain nodes to a custom location in the array. Properties to specify on an area group are described in the following table.

Table 1. Area Group Properties
Property Description
group Specify the collection of group. Each group can be:
  • tile-type: Specify the tile-type for the group. Supported tile-types are aie_tile, shim_tile, or memory_tile. Currently only one rectangle for each type is supported.
  • column_min: Column index for lower left corner of the group.
  • row_min: Row index for lower left corner of the group.
  • column_max: Column index for upper right corner of the group.
  • row_max: Row index for upper right corner of the group.
contain_routing A boolean value that when specified true ensures all routing, including nets between nodes contained in the nodeGroup, is contained within the area group.
exclusive_routing A boolean value that when specified true ensures all routing, excluding nets between nodes from the nodeGroup, is excluded from the area group.
exclusive_placement A boolean value that when specified true prevents all nodes not included in the nodeGroup from being placed within the area group bounding box.

The following examples show how an area location constraint can be applied in a graph file.

using namespace adf;

class testGraph1: public adf::graph {

    private:
        kernel first;
        kernel second;
    public:
        testGraph1()  {
            first = kernel::create(simple1);
            second = kernel::create(simple2);
            connect< window<128> > net1 (first.out[0], second.in[0]);
            source(first) = "src/kernels/kernels.cc";
            source(second) = "src/kernels/kernels.cc";
            runtime<ratio>(first) = 0.1;
            runtime<ratio>(second) = 0.1;

            // Create area group with some valid ranges.
            location<graph>(*this) = area_group({{aie_tile, 0, 0, 1, 7}, {shim_tile, 0, 0, 1, 0}});
        }

};
using namespace adf;

class testGraph2: public adf::graph {

    private:
        kernel first;
        kernel second;
    public:
        testGraph2()  {
            first = kernel::create(simple1);
            second = kernel::create(simple2);
            connect< window<128> > net1 (first.out[0], second.in[0]);
            source(first) = "src/kernels/kernels.cc";
            source(second) = "src/kernels/kernels.cc";
            runtime<ratio>(first) = 0.1;
            runtime<ratio>(second) = 0.1;

            // Explicitly specify contain_routing, exclusive_routing, exclusive_placement.
            location<graph>(*this) = area_group({{aie_tile, 0, 0, 1, 7}, {shim_tile, 0, 0, 1, 0}}, true, false, true);
        }

};

The following table clarifies whether the nodes and nets can access the resources of the area group given various combinations of the flags. The use cases presented in the table as columns are illustrated in the figure that follows. Two important things to consider when applying the rules from the following table.

  • Broadcast nets that are driven from one node to several destination nodes, are considered as individual point-to-point nets
  • Any FIFOs on a net (stream switch or DMA) adhere to the same conditions as the net. For example, if a net is fully contained in an area group (both driver and receiver are contained in the area group) and the contain_routing flag is used, then the following table indicates that the net routing must be fully contained in the area group. Similarly, any FIFOs on that net, must also be placed within the boundary of the area group.
Table 2. Permission to use Area Group Resources with the Stated Conditions
contain_routing exclusive_routing exclusive_placement Placement of Nodes Contained in the Area Group (1) Placement of Nodes External to the Area Group (2) Routes between Nodes Fully Contained in the Area group (3) Routes between Nodes Spanning the Area Group (4) Routes between Nodes Entirely External to the Area Group (5)
False False False Must May May May May
False False True Must Must Not May May May
False True False Must May May May Must Not
False True True Must Must Not May May Must Not
True False False Must May Must May May
True False True Must Must Not Must May May
True True False Must May Must May Must Not
True True True Must Must Not Must May Must Not

An illustration of the use cases is shown in the following figure.

Figure 1. Use Cases