Contexts

Classes

class VprContext : public Context

This object encapsulates VPR’s state.

There is typically a single instance which is accessed via the global variable g_vpr_ctx (see globals.h/.cpp).

It is divided up into separate sub-contexts of logically related data structures.

Each sub-context can be accessed via member functions which return a reference to the sub-context:

• The default the member function (e.g. device()) return an const (immutable) reference providing read-only access to the context. This should be the preferred form, as the compiler will detect unintentional state changes.

• The ‘mutable’ member function (e.g. mutable_device()) will return a non-const (mutable) reference allowing modification of the context. This should only be used on an as-needed basis.

Typical usage in VPR would be to call the appropriate accessor to get a reference to the context of interest, and then operate on it.

For example if we were performing an action which required access to the current placement, we would do:

void my_analysis_algorithm() {
    //Get read-only access to the placement
    auto& place_ctx = g_vpr_ctx.placement();

    //Do something that depends on (but does not change)
    //the current placement...

}

If we needed to modify the placement (e.g. we were implementing another placement algorithm) we would do:

void my_placement_algorithm() {
    //Get read-write access to the placement
    auto& place_ctx = g_vpr_ctx.mutable_placement();

    //Do something that modifies the placement
    //...
}

Note

The returned contexts are not copyable, so they must be taken by reference.

Structures

struct AtomContext : public Context

State relating to the atom-level netlist.

This should contain only data structures related to user specified netlist being implemented by VPR onto the target device.

Public Functions

inline AtomContext()

constructor

In the constructor initialize the list of pack molecules to nullptr and defines a custom deletor for it

Public Members

AtomNetlist nlist

Atom netlist.

AtomLookup lookup

Mappings to/from the Atom Netlist to physically described .blif models.

std::multimap<AtomBlockId, t_pack_molecule*> atom_molecules

The molecules associated with each atom block.

This map is loaded in the pre-packing stage and freed at the very end of vpr flow run. The pointers in this multimap is shared with list_of_pack_molecules.

std::unique_ptr<t_pack_molecule, decltype(&free_pack_molecules)> list_of_pack_molecules

A linked list of all the packing molecules that are loaded in pre-packing stage.

Is is useful in freeing the pack molecules at the destructor of the Atom context using free_pack_molecules.

struct ClusteringContext : public Context

State relating to clustering.

This should contain only data structures that describe the current clustering/packing, or related clusterer/packer algorithmic state.

Public Members

ClusteredNetlist clb_nlist

New netlist class derived from Netlist.

struct Context

A Context is collection of state relating to a particular part of VPR.

This is a base class who’s only purpose is to disable copying of contexts. This ensures that attempting to use a context by value (instead of by reference) will result in a compilation error.

No data or member functions should be defined in this class!

Subclassed by AtomContext, ClusteringContext, ClusteringHelperContext, DeviceContext, FloorplanningContext, NocContext, PackingMultithreadingContext, PlacementContext, PlacerContext, PlacerMoveContext, PlacerRuntimeContext, PlacerTimingContext, PowerContext, RoutingContext, TimingContext, VprContext

struct DeviceContext : public Context

State relating the device.

This should contain only data structures describing the targeted device.

Public Members

DeviceGrid grid

The device grid.

This represents the physical layout of the device. To get the physical tile at each location (layer_num, x, y) the helper functions in this data structure should be used.

bool has_multiple_equivalent_tiles

Boolean that indicates whether the architecture implements an N:M physical tiles to logical blocks mapping.

t_chan_width chan_width

chan_width is for x|y-directed channels; i.e. between rows

std::vector<t_rr_rc_data> rr_rc_data

Fly-weighted Resistance/Capacitance data for RR Nodes.

std::vector<std::vector<RRNodeId>> rr_non_config_node_sets

Sets of non-configurably connected nodes.

std::unordered_map<RRNodeId, int> rr_node_to_non_config_node_set

Reverse look-up from RR node to non-configurably connected node set (index into rr_non_config_node_sets)

int virtual_clock_network_root_idx

rr_node idx that connects to the input of all clock network wires

Useful for two stage clock routing XXX: currently only one place to source the clock networks so only storing a single value

std::vector<std::map<int, int>> switch_fanin_remap

switch_fanin_remap is only used for printing out switch fanin stats (the -switch_stats option)

array index: [0..(num_arch_switches-1)]; map key: num of all possible fanin of that type of switch on chip map value: remapped switch index (index in rr_switch_inf)

std::string read_rr_graph_filename

Name of rrgraph file read (if any).

Used to determine when reading rrgraph if file is already loaded.

struct PlacementContext : public Context

State relating to placement.

This should contain only data structures that describe the current placement, or related placer algorithm state.

Public Members

vtr::vector_map<ClusterBlockId, t_block_loc> block_locs

Clustered block placement locations.

vtr::vector_map<ClusterPinId, int> physical_pins

Clustered pin placement mapping with physical pin.

GridBlock grid_blocks

Clustered block associated with each grid location (i.e. inverse of block_locs)

std::vector<t_pl_macro> pl_macros

The pl_macros array stores all the placement macros (usually carry chains).

t_compressed_block_grids compressed_block_grids

Compressed grid space for each block type.

Used to efficiently find logically ‘adjacent’ blocks of the same block type even though the may be physically far apart Indexed with logical block type index: [0…num_logical_block_types-1] -> logical block compressed grid

std::string placement_id

SHA256 digest of the .place file.

Used for unique identification and consistency checking

bool f_placer_debug = false

Use during placement to print extra debug information. It is set to true based on the number assigned to placer_debug_net or placer_debug_block parameters in the command line.

bool cube_bb = false

Set this variable to ture if the type of the bounding box used in placement is of the type cube. If it is false, it would mean that per-layer bounding box is used. For the 2D architecture, the cube bounding box would be used.

struct PowerContext : public Context

State relating to power analysis.

This should contain only data structures related to power analysis, or related power analysis algorithmic state.

Public Members

std::unordered_map<AtomNetId, t_net_power> atom_net_power

Atom net power info.

struct RoutingContext : public Context

State relating to routing.

This should contain only data structures that describe the current routing implementation, or related router algorithmic state.

Public Members

vtr::dynamic_bitset<RRNodeId> non_configurable_bitset

Information about whether a node is part of a non-configurable set.

(i.e. connected to others with non-configurable edges like metal shorts that can’t be disabled) Stored in a single bit per rr_node for efficiency bit value 0: node is not part of a non-configurable set bit value 1: node is part of a non-configurable set Initialized once when RoutingContext is initialized, static throughout invocation of router

t_net_routing_status net_status

Information about current routing status of each net.

vtr::vector<ParentNetId, t_bb> route_bb

Limits area within which each net must be routed.

std::string routing_id

SHA256 digest of the .route file.

Used for unique identification and consistency checking

vtr::Cache<std::tuple<e_router_lookahead, std::string, std::vector<t_segment_inf>>, RouterLookahead> cached_router_lookahead_

Cache of router lookahead object.

Cache key: (lookahead type, read lookahead (if any), segment definitions).

struct TimingContext : public Context

State relating to timing.

This should contain only data structures related to timing analysis, or related timing analysis algorithmic state.

Public Members

std::shared_ptr<tatum::TimingGraph> graph

The current timing graph.

This represents the timing dependencies between pins of the atom netlist

std::shared_ptr<tatum::TimingConstraints> constraints

The current timing constraints, as loaded from an SDC file (or set by default).

These specify how timing analysis is performed (e.g. target clock periods)