Apparatus and method for analyzing post-layout timing critical paths
View Patent ↗A critical path detecting unit for detecting critical paths for a design in which cells are placed on an integrated circuit and information concerning timing constraints. A representative-critical-path extracting unit extracts a representative critical path by having one critical path represent critical paths which share more intervals than a certain number, and which are similar to one another, out of critical paths which have been detected by the critical path detecting unit. A path-image generating unit renders the representative critical path, which has been extracted by the representative-critical-path extracting unit and reflects information concerning other critical paths, which are similar to the representative critical path, on the representative critical path.
1. A signal propagating path rendering method which causes a computer to render a signal propagating path of a semiconductor integrated circuit, the method comprising:
a first step wherein the computer detects a critical path based on design data in which cells are disposed on a chip of a semiconductor integrated circuit and timing constraint information on the chip, and stores the critical paths in a memory device;
a second step wherein the computer reads out a critical path from the memory to extract a representative critical path to represent with a single path the mutually similar paths that share more than a predetermined number of intervals in the paths; and
a third step wherein the computer reads out a representative critical path from the memory, and renders the representative critical path, incorporating other critical path data similar to each representative critical path.
2. A signal-propagating path rendering method according to claim 1 , wherein, in the second step:
the computer extracts, as a representative critical path, the path wherein the signal propagation is slowest, from the predetermined timing conditions, among the mutually similar critical paths.
3. A signal-propagating path rendering method according to claim 1 , wherein, it in the third step:
the computer renders a representative critical path using lines of differing thicknesses in accordance with the numbers of similar other critical paths.
4. A signal-propagating path rendering method according to claim 1 , wherein:
in the second step, the computer divides a critical path into segments that are intervals between each two adjacent gate pins, out of a plurality of gate pins through which a path passes from the start point through the end point, and counts the number of critical paths passing through the segment; and
in the third step, the computer renders individual segments of the representative critical path using lines of differing thicknesses in accordance with the values counted in the second step.