report_timing Accurate Delay Symbols in IC Compiler

In IC Compiler (ICC) timing report, we can see symbols like "@ c * & z", what’s the meaning of those symbols?

In IC Compiler (ICC) timing report, we can see symbols like "@ c * & z", what’s the meaning of those symbols?

Example timing report:

Information: Percent of CCS-based delays = 97.08%

  Startpoint: A/B_ram/C
              (rising edge-triggered flip-flop clocked by clk0)
  Endpoint: A/B_ram/reg_1
            (rising edge-triggered flip-flop clocked by clk)
  Path Group: clk
  Path Type: max

  Point                          Fanout        Cap     Trans      Incr        Path
  ---------------------------------------------------------------------------------
  clock clk0 (rise edge)                                         1.260       1.260
  clock source latency                                           2.624       3.884 r
  ......

  A/B_clkcon/en_1/CP (CKLNEQD12)                       0.119     0.015 c     4.169 r
  A/B_clkcon/en_1/Q (CKLNEQD12)                        0.086     0.207 @     4.377 r
  A/B_clkcon/clk_ (net)               1        0.003             0.000       4.377 r
  
.....

The mean of the symbols are listed in the following table:

# mark : calc    , library ;# reason
#-----------------------------------------------------------------
#  @   : arnoldi , NLDM    ;#
#  c   : arnoldi , CCS     ;#
#  *   : elmore  , *       ;#
#  &   : elmore  ,         ;# rd/rc threshold is insufficient
#  z   : zic     ,         ;# set_zero_interconnect_delay
#-----------------------------------------------------------------

For example:

  • "c" means delay calculated by Arnoldi using CCS libraries
  • "@" means delay calculated by Arnoldi using NLDM libraries

report_timing man page:

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