SRC/path_delay2.c

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#include <assert.h>
#include "util.h"
#include "vpr_types.h"
#include "globals.h"
#include "path_delay2.h"


/************* Variables (globals) shared by all path_delay modules **********/

t_tnode *tnode;                 /* [0..num_tnodes - 1] */
t_tnode_descript *tnode_descript;       /* [0..num_tnodes - 1] */
int num_tnodes;                 /* Number of nodes (pins) in the timing graph */

/* [0..num_nets - 1].  Gives the index of the tnode that drives each net. */

int *net_to_driver_tnode;


/* [0..num__tnode_levels - 1].  Count and list of tnodes at each level of    *
 * the timing graph, to make breadth-first searches easier.                  */

struct s_ivec *tnodes_at_level;
int num_tnode_levels;           /* Number of levels in the timing graph. */



/******************* Subroutines local to this module ************************/

static int *alloc_and_load_tnode_fanin_and_check_edges(int *num_sinks_ptr);



/************************** Subroutine definitions ***************************/


static int *
alloc_and_load_tnode_fanin_and_check_edges(int *num_sinks_ptr)
{

/* Allocates an array and fills it with the number of in-edges (inputs) to   *
 * each tnode.  While doing this it also checks that each edge in the timing *
 * graph points to a valid tnode. Also counts the number of sinks.           */

    int inode, iedge, to_node, num_edges, error, num_sinks;
    int *tnode_num_fanin;
    t_tedge *tedge;

    tnode_num_fanin = (int *)my_calloc(num_tnodes, sizeof(int));
    error = 0;
    num_sinks = 0;

    for(inode = 0; inode < num_tnodes; inode++)
        {
            num_edges = tnode[inode].num_edges;

            if(num_edges > 0)
                {
                    tedge = tnode[inode].out_edges;
                    for(iedge = 0; iedge < num_edges; iedge++)
                        {
                            to_node = tedge[iedge].to_node;

                            if(to_node < 0 || to_node >= num_tnodes)
                                {
                                    printf
                                        ("Error in alloc_and_load_tnode_fanin_and_check_edges:\n"
                                         "tnode #%d edge #%d goes to illegal node #%d.\n",
                                         inode, iedge, to_node);
                                    error++;
                                }

                            tnode_num_fanin[to_node]++;
                        }
                }

            else if(num_edges == 0)
                {
                    num_sinks++;
                }

            else
                {
                    printf
                        ("Error in alloc_and_load_tnode_fanin_and_check_edges: \n"
                         "tnode #%d has %d edges.\n", inode, num_edges);
                    error++;
                }

        }

    if(error != 0)
        {
            printf("Found %d Errors in the timing graph.  Aborting.\n",
                   error);
            exit(1);
        }

    *num_sinks_ptr = num_sinks;
    return (tnode_num_fanin);
}


int
alloc_and_load_timing_graph_levels(void)
{

/* Does a breadth-first search through the timing graph in order to levelize *
 * it.  This allows subsequent breadth-first traversals to be faster. Also   *
 * returns the number of sinks in the graph (nodes with no fanout).          */

    t_linked_int *free_list_head, *nodes_at_level_head;
    int inode, num_at_level, iedge, to_node, num_edges, num_sinks,
        num_levels, i;
    t_tedge *tedge;

/* [0..num_tnodes-1]. # of in-edges to each tnode that have not yet been    *
 * seen in this traversal.                                                  */

    int *tnode_fanin_left;


    tnode_fanin_left = alloc_and_load_tnode_fanin_and_check_edges(&num_sinks);

    free_list_head = NULL;
    nodes_at_level_head = NULL;

/* Very conservative -> max number of levels = num_tnodes.  Realloc later.  *
 * Temporarily need one extra level on the end because I look at the first  *
 * empty level.                                                             */

    tnodes_at_level = (struct s_ivec *)my_malloc((num_tnodes + 1) *
                                                 sizeof(struct s_ivec));

/* Scan through the timing graph, putting all the primary input nodes (no    *
 * fanin) into level 0 of the level structure.                               */

    num_at_level = 0;

    for(inode = 0; inode < num_tnodes; inode++)
        {
            if(tnode_fanin_left[inode] == 0)
                {
                    num_at_level++;
                    nodes_at_level_head =
                        insert_in_int_list(nodes_at_level_head, inode,
                                           &free_list_head);
                }
        }

    alloc_ivector_and_copy_int_list(&nodes_at_level_head, num_at_level,
                                    &tnodes_at_level[0], &free_list_head);

    num_levels = 0;

    while(num_at_level != 0)
        {                       /* Until there's nothing in the queue. */
            num_levels++;
            num_at_level = 0;

            for(i = 0; i < tnodes_at_level[num_levels - 1].nelem; i++)
                {
                    inode = tnodes_at_level[num_levels - 1].list[i];
                    tedge = tnode[inode].out_edges;
                    num_edges = tnode[inode].num_edges;

                    for(iedge = 0; iedge < num_edges; iedge++)
                        {
                            to_node = tedge[iedge].to_node;
                            tnode_fanin_left[to_node]--;

                            if(tnode_fanin_left[to_node] == 0)
                                {
                                    num_at_level++;
                                    nodes_at_level_head =
                                        insert_in_int_list
                                        (nodes_at_level_head, to_node,
                                         &free_list_head);
                                }
                        }
                }

            alloc_ivector_and_copy_int_list(&nodes_at_level_head,
                                            num_at_level,
                                            &tnodes_at_level[num_levels],
                                            &free_list_head);
        }

    tnodes_at_level =
        (struct s_ivec *)my_realloc(tnodes_at_level,
                                    num_levels * sizeof(struct s_ivec));
    num_tnode_levels = num_levels;

    free(tnode_fanin_left);
    free_int_list(&free_list_head);
    return (num_sinks);
}


void
check_timing_graph(int num_const_gen,
                   int num_ff,
                   int num_sinks)
{

/* Checks the timing graph to see that: (1) all the tnodes have been put    *
 * into some level of the timing graph; (2) the number of primary inputs    *
 * to the timing graph is equal to the number of input pads + the number of *
 * constant generators; and (3) the number of sinks (nodes with no fanout)  *
 * equals the number of output pads + the number of flip flops.             */

    int i, j, num_tnodes_check, ilevel, inet, inode, error, num_p_inputs,
        num_p_outputs;

    error = 0;
    num_tnodes_check = 0;
    num_p_inputs = 0;
    num_p_outputs = 0;

    /* Count I/O input and output pads */
    for(i = 0; i < num_blocks; i++)
        {
            if(block[i].type == IO_TYPE)
                {
                    for(j = 0; j < IO_TYPE->num_pins; j++)
                        {
                            if(block[i].nets[j] != OPEN)
                                {
                                    if(IO_TYPE->
                                       class_inf[IO_TYPE->pin_class[j]].
                                       type == DRIVER)
                                        {
                                            num_p_inputs++;
                                        }
                                    else
                                        {
                                            assert(IO_TYPE->
                                                   class_inf[IO_TYPE->
                                                             pin_class[j]].
                                                   type == RECEIVER);
                                            num_p_outputs++;
                                        }
                                }
                        }
                }
        }

    for(ilevel = 0; ilevel < num_tnode_levels; ilevel++)
        num_tnodes_check += tnodes_at_level[ilevel].nelem;

    if(num_tnodes_check != num_tnodes)
        {
            printf
                ("Error in check_timing_graph: %d tnodes appear in the tnode level "
                 "structure.  Expected %d.\n", num_tnodes_check, num_tnodes);
            printf("Check the netlist for combinational cycles.\n");
            error++;
        }

    if(num_const_gen + num_p_inputs != tnodes_at_level[0].nelem)
        {
            printf
                ("Error in check_timing_graph: %d tnodes are sources (have no "
                 "inputs -- expected %d.\n", tnodes_at_level[0].nelem,
                 num_const_gen + num_p_inputs);
            error++;
        }

    if(num_sinks != num_p_outputs + num_ff)
        {
            printf
                ("Error in check_timing_graph: %d tnodes are sinks (have no "
                 "outputs -- expected %d.\n", num_sinks,
                 num_ff + num_p_outputs);
            error++;
        }

    for(inet = 0; inet < num_nets; inet++)
        {
            inode = net_to_driver_tnode[inet];
            if(inode < 0 || inode >= num_tnodes)
                {
                    printf("Error in check_timing_graph:\n"
                           "\tdriver of net %d has a tnode mapping of %d (out of range).\n",
                           inet, inode);
                    error++;
                }
        }

    if(error != 0)
        {
            printf("Found %d Errors in the timing graph.  Aborting.\n",
                   error);
            exit(1);
        }
}


float
print_critical_path_node(FILE * fp,
                         t_linked_int * critical_path_node,
                         t_subblock_data subblock_data)
{

/* Prints one tnode on the critical path out to fp. Returns the delay to    *
 * the next node.                                                           */

    int inode, iblk, ipin, inet, downstream_node;
    t_tnode_type type;
    static char *tnode_type_names[] = { "INPAD_SOURCE", "INPAD_OPIN",
        "OUTPAD_IPIN", "OUTPAD_SINK", "CLB_IPIN", "CLB_OPIN",
        "SUBBLK_IPIN", "SUBBLK_OPIN", "FF_SINK", "FF_SOURCE",
        "CONSTANT_GEN_SOURCE"
    };                          /* NB: static for speed */
    t_linked_int *next_crit_node;
    float Tdel;

    inode = critical_path_node->data;
    type = tnode_descript[inode].type;
    iblk = tnode_descript[inode].iblk;
    ipin = tnode_descript[inode].ipin;

    fprintf(fp, "Node: %d  %s Block #%d (%s)\n", inode,
            tnode_type_names[type], iblk, block[iblk].name);

    if(type != INPAD_SOURCE && type != OUTPAD_SINK && type != FF_SINK &&
       type != FF_SOURCE && type != CONSTANT_GEN_SOURCE)
        {
            fprintf(fp, "Pin: %d ", ipin);
        }

    if(type == SUBBLK_IPIN || type == SUBBLK_OPIN || type == FF_SINK
       || type == FF_SOURCE || type == CONSTANT_GEN_SOURCE)
        {
            fprintf(fp, "Subblock #%d subpin #%d",
                    tnode_descript[inode].isubblk,
                    tnode_descript[inode].ipin);
        }

    if(type != INPAD_SOURCE && type != OUTPAD_SINK)
        {
            fprintf(fp, "\n");
        }

    fprintf(fp, "T_arr: %g  T_req: %g  ", tnode[inode].T_arr,
            tnode[inode].T_req);

    next_crit_node = critical_path_node->next;
    if(next_crit_node != NULL)
        {
            downstream_node = next_crit_node->data;
            Tdel = tnode[downstream_node].T_arr - tnode[inode].T_arr;
            fprintf(fp, "Tdel: %g\n", Tdel);
        }
    else
        {                       /* last node, no Tdel. */
            Tdel = 0.;
            fprintf(fp, "\n");
        }

    if(type == FB_OPIN)
        {
            inet = block[iblk].nets[ipin];
            fprintf(fp, "Net to next node: #%d (%s).  Pins on net: %d.\n",
                    inet, net[inet].name, (net[inet].num_sinks + 1));
        }

    if(type == INPAD_OPIN)
        {
            ipin =
                subblock_data.subblock_inf[iblk][tnode_descript[inode].
                                                 isubblk].outputs[ipin];
            inet = block[iblk].nets[ipin];
            fprintf(fp, "Net to next node: #%d (%s).  Pins on net: %d.\n",
                    inet, net[inet].name, (net[inet].num_sinks + 1));
        }

    fprintf(fp, "\n");
    return (Tdel);
}

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