How can I find the skew for a path?

[oharboe]

I would like to find the skew for a path.

How can I do that?

Below I'm associating slack with a position, but I would like to associate skew with an x,y position.

source $::env(SCRIPTS_DIR)/load.tcl
load_design 4_cts.odb 4_cts.sdc

set paths [find_timing_paths -path_group reg2reg -sort_by_slack -group_count 1000000]

set db [::ord::get_db]
set block [[$db getChip] getBlock]

foreach path $paths {
  set endpoint [get_property $path endpoint]
  set instance [sta::sta_to_db_inst [$endpoint instance]]
  set port [sta::sta_to_db_port [$endpoint port]]
  set name [get_property $endpoint full_name]
  set obj {NULL}
  if {$port!={NULL}} {
    set obj $port
  } elseif {$instance!={NULL}} {
    set obj $instance
  } else {
    puts "Nothing found for $name"
    continue
  }
  set slack [get_property $path slack]
  set bbox [$obj getBBox]
  puts "$name $slack [ord::dbu_to_microns [$bbox xMin]] [ord::dbu_to_microns [$bbox yMin]]"
}

$ make RUN_SCRIPT=slack-positions.tcl run
/home/oyvind/OpenROAD-flow-scripts/tools/install/OpenROAD/bin/openroad -exit -no_init -threads 16  -no_splash  slack-positions.tcl
[WARNING STA-0527] unknown path group 'reg2reg'.
resp_msg[15] -0.029667 21.305 36.24
dpath.a_reg.out[7]$_DFFE_PP_/D -0.028715 31.35 18.2
[deleted]
req_rdy 0.194209 0.0 12.88

[oharboe]

Found this, now it works.

I had to change from load.tcl to open.tcl to make timing match the OpenROAD GUI because otherwise all timing information isn't loaded.

OpenSTA/search/Search.i

Line 1408 in dfb95b1

Delay clk_skew() { return self->clkSkew(Sta::sta()); }

source $::env(SCRIPTS_DIR)/open.tcl

set paths [find_timing_paths -path_group reg2reg -sort_by_slack -group_count 5]

set db [::ord::get_db]
set block [[$db getChip] getBlock]

foreach path $paths {
  set endpoint [get_property $path endpoint]
  set instance [sta::sta_to_db_inst [$endpoint instance]]
  set port [sta::sta_to_db_port [$endpoint port]]
  set name [get_property $endpoint full_name]
  set obj {NULL}
  if {$port!={NULL}} {
    set obj $port
  } elseif {$instance!={NULL}} {
    set obj $instance
  } else {
    puts "Nothing found for $name"
    continue
  }
  set slack [get_property $path slack]
  set skew [$path clk_skew]
  set bbox [$obj getBBox]
  puts "$name $slack $skew [ord::dbu_to_microns [$bbox xMin]] [ord::dbu_to_microns [$bbox yMin]]"
}

report_checks

$ make ODB_FILE=results/asap7/riscv32i/base/4_cts.odb DESIGN_CONFIG=designs/asap7/riscv32i/config.mk RUN_SCRIPT=slack-positions.tcl run
/home/oyvind/OpenROAD-flow-scripts/tools/install/OpenROAD/bin/openroad -exit -no_init -threads 16  -no_splash  slack-positions.tcl
GUI_TIMING=1 reading timing, takes a little while for large designs...
estimate_parasitics -placement
Populating timing paths...
[WARNING STA-0527] unknown path group 'reg2reg'.
riscv/dp/rf.rf[17][21]$_DFFE_PP_/D 1.861955 5.46902800824256e-12 71.28 75.06
riscv/dp/rf.rf[19][21]$_DFFE_PP_/D 1.876277 5.0797629991272686e-12 69.768 76.41
riscv/dp/rf.rf[16][21]$_DFFE_PP_/D 1.948330 5.114117462845513e-12 69.228 75.87
riscv/dp/rf.rf[18][21]$_DFFE_PP_/D 2.141176 5.20548187887826e-12 70.47 75.6
riscv/dp/rf.rf[7][12]$_DFFE_PP_/D 2.731038 7.583253469611861e-12 64.746 72.63
Startpoint: reset (input port clocked by clk)
Endpoint: riscv/dp/pcreg.q[20]$_DFF_PP0_
          (recovery check against rising-edge clock clk)
Path Group: asynchronous
Path Type: max

  Delay    Time   Description
---------------------------------------------------------
   0.00    0.00   clock clk (rise edge)
   0.00    0.00   clock network delay (propagated)
 157.50  157.50 v input external delay
   0.00  157.50 v reset (in)
  15.13  172.63 v input33/Y (BUFx6f_ASAP7_75t_R)
  13.34  185.97 ^ riscv/dp/_16042_/Y (CKINVDCx20_ASAP7_75t_R)
   6.44  192.41 ^ riscv/dp/pcreg.q[20]$_DFF_PP0_/SETN (DFFASRHQNx1_ASAP7_75t_R)
         192.41   data arrival time

1260.00 1260.00   clock clk (rise edge)
  97.37 1357.37   clock network delay (propagated)
   0.00 1357.37   clock reconvergence pessimism
        1357.37 ^ riscv/dp/pcreg.q[20]$_DFF_PP0_/CLK (DFFASRHQNx1_ASAP7_75t_R)
   4.44 1361.80   library recovery time
        1361.80   data required time
---------------------------------------------------------
        1361.80   data required time
        -192.41   data arrival time
---------------------------------------------------------
        1169.39   slack (MET)


Startpoint: riscv/dp/pcreg.q[24]$_DFF_PP0_
            (rising edge-triggered flip-flop clocked by clk)
Endpoint: riscv/dp/rf.rf[17][21]$_DFFE_PP_
          (rising edge-triggered flip-flop clocked by clk)
Path Group: clk
Path Type: max

  Delay    Time   Description
---------------------------------------------------------
   0.00    0.00   clock clk (rise edge)
 103.29  103.29   clock network delay (propagated)
   0.00  103.29 ^ riscv/dp/pcreg.q[24]$_DFF_PP0_/CLK (DFFASRHQNx1_ASAP7_75t_R)
  62.16  165.45 ^ riscv/dp/pcreg.q[24]$_DFF_PP0_/QN (DFFASRHQNx1_ASAP7_75t_R)
  18.89  184.34 v riscv/dp/_11888_/Y (INVx1_ASAP7_75t_R)
  35.06  219.40 v _19_/Y (OR4x1_ASAP7_75t_R)
  10.98  230.38 ^ _21_/Y (NOR2x1_ASAP7_75t_R)
  33.73  264.12 ^ _31_/Y (AND4x2_ASAP7_75t_R)
  18.46  282.57 ^ _32_/Y (BUFx6f_ASAP7_75t_R)
  15.75  298.32 ^ _45_/Y (AO21x1_ASAP7_75t_R)
  21.87  320.19 ^ riscv/_080_/Y (AND2x2_ASAP7_75t_R)
  36.27  356.47 ^ riscv/_081_/Y (AND4x2_ASAP7_75t_R)
  20.64  377.10 v riscv/_082_/Y (NAND2x2_ASAP7_75t_R)
  23.55  400.65 ^ riscv/_083_/Y (CKINVDCx12_ASAP7_75t_R)
  31.98  432.63 v riscv/dp/_10272_/Y (CKINVDCx5p33_ASAP7_75t_R)
  22.33  454.96 v riscv/dp/_10321_/Y (BUFx6f_ASAP7_75t_R)
  20.30  475.26 v riscv/dp/_10368_/Y (BUFx6f_ASAP7_75t_R)
  18.28  493.55 v riscv/dp/_10369_/Y (BUFx6f_ASAP7_75t_R)
  23.05  516.60 v riscv/dp/_10370_/Y (BUFx12f_ASAP7_75t_R)
  46.82  563.42 v riscv/dp/_10371_/Y (BUFx4f_ASAP7_75t_R)
  19.26  582.68 v riscv/dp/_10372_/Y (BUFx6f_ASAP7_75t_R)
  34.13  616.81 v riscv/dp/_14286_/Y (OA211x2_ASAP7_75t_R)
  19.39  636.20 v riscv/dp/_14287_/Y (AND2x2_ASAP7_75t_R)
  11.23  647.43 ^ riscv/dp/_14288_/Y (AOI21x1_ASAP7_75t_R)
  13.83  661.26 v riscv/dp/_14289_/Y (XNOR2x1_ASAP7_75t_R)
  82.52  743.77 v riscv/dp/_19480_/SN (HAxp5_ASAP7_75t_R)
  35.96  779.73 v riscv/dp/_15314_/Y (OA21x2_ASAP7_75t_R)
  19.20  798.93 v riscv/dp/_15457_/Y (OA21x2_ASAP7_75t_R)
  16.21  815.14 v riscv/dp/_15458_/Y (OA21x2_ASAP7_75t_R)
  16.36  831.51 v riscv/dp/_15459_/Y (OA21x2_ASAP7_75t_R)
  17.73  849.24 v riscv/dp/_15460_/Y (OA21x2_ASAP7_75t_R)
  23.03  872.27 v riscv/dp/_15579_/Y (OA211x2_ASAP7_75t_R)
  14.12  886.39 v riscv/dp/_15797_/Y (AND3x1_ASAP7_75t_R)
  15.42  901.81 v riscv/dp/_15798_/Y (OA21x2_ASAP7_75t_R)
  17.91  919.72 ^ riscv/dp/_15926_/Y (OAI21x1_ASAP7_75t_R)
  17.69  937.41 v riscv/dp/_16030_/Y (AOI211x1_ASAP7_75t_R)
  24.09  961.49 ^ riscv/dp/_16031_/Y (AOI21x1_ASAP7_75t_R)
  34.31  995.80 v riscv/dp/_16032_/Y (NAND2x2_ASAP7_75t_R)
  30.84 1026.64 v dmem/_155_/Y (BUFx6f_ASAP7_75t_R)
  52.26 1078.90 v dmem/_156_/Y (OR3x4_ASAP7_75t_R)
  23.08 1101.98 v dmem/_283_/Y (BUFx6f_ASAP7_75t_R)
  20.62 1122.61 v dmem/_329_/Y (OA22x2_ASAP7_75t_R)
  14.18 1136.79 v dmem/_330_/Y (OA21x2_ASAP7_75t_R)
  16.43 1153.21 v riscv/dp/_16170_/Y (AND4x1_ASAP7_75t_R)
  24.46 1177.68 v riscv/dp/_16238_/Y (OR3x1_ASAP7_75t_R)
  19.36 1197.04 v riscv/dp/_16239_/Y (BUFx3_ASAP7_75t_R)
  11.76 1208.80 ^ riscv/dp/_16409_/Y (AOI21x1_ASAP7_75t_R)
  22.28 1231.08 v riscv/dp/_16410_/Y (AOI221x1_ASAP7_75t_R)
  28.87 1259.95 v riscv/dp/_16411_/Y (AND2x2_ASAP7_75t_R)
  27.62 1287.57 v riscv/dp/_16413_/Y (AO21x2_ASAP7_75t_R)
  42.13 1329.70 v riscv/dp/_16730_/Y (BUFx4f_ASAP7_75t_R)
  23.43 1353.13 v riscv/dp/_17237_/Y (AO21x1_ASAP7_75t_R)
   0.01 1353.13 v riscv/dp/rf.rf[17][21]$_DFFE_PP_/D (DFFHQNx2_ASAP7_75t_R)
        1353.13   data arrival time

1260.00 1260.00   clock clk (rise edge)
  96.17 1356.17   clock network delay (propagated)
   1.65 1357.82   clock reconvergence pessimism
        1357.82 ^ riscv/dp/rf.rf[17][21]$_DFFE_PP_/CLK (DFFHQNx2_ASAP7_75t_R)
  -2.83 1354.99   library setup time
        1354.99   data required time
---------------------------------------------------------
        1354.99   data required time
        -1353.13   data arrival time
---------------------------------------------------------
           1.86   slack (MET)