Intel® Quartus® Prime Pro Edition User Guide: Design Compilation

ID 683236
Date 12/04/2023
Public
Document Table of Contents
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2.6.3.6. Types of SDC Files Used in the Intel® Quartus® Prime Software

This section provides a high-level summary of the differences between various SDC file types available for use.

The Intel® Quartus® Prime software uses conventional SDC files to target the timing netlist. These SDCs are not applied until the Fitter plan stage completes. However, for Post-Synthesis Static Timing Analysis (STA), you can introduce SDC files to the Intel® Quartus® Prime software in one of the following ways:

The following table attempts to summarize the differences between the various SDC file types:

Table 18.  Types of SDC Files Used in the Intel® Quartus® Prime Software
  SDC-on-RTL Synthesis SDC SDC (Conventional)
Stage where constraints are read Analysis & Elaboration Synthesis Fitter, Signoff

Stage where constraints are processed

Synthesis through Fitter

Synthesis only

Fitter, Signoff

QSF assignment

RTL_SDC_FILE (supports entities)

SDC_FILE SDC_ENTITY_FILE -read_during_post_syn_and_post_fit_timing_analysis

SDC_FILE SDC_ENTITY_FILE -read_during_post_syn_and_not_post_fit_timing_analysis

SDC_FILE

Syntax supported

Tcl with SDC 2.1 commands

Tcl with Intel® Quartus® Prime SDC commands

Tcl with Intel® Quartus® Prime SDC commands

SDC 2.1-compliant

Yes No No

Target type

RTL

Intel® Quartus® Prime timing graph

Intel® Quartus® Prime timing graph

Hierarchical targets

Yes No No

Buried timing nodes (used by IP)

No
Core fabric only.
Note: Such nodes do not exist for the periphery in post-synthesis STA.
Yes

STA command to load constraints

Executes the read_sdc or import_sdc command in any snapshot.

Executes the read_sdc command only during static timing analysis on the synthesized snapshot.

Executes the read_sdc command during static timing analysis on any fitter snapshot (plan, place, route, retime).

Note: Not loaded during synthesis.

As shown in the table, the assignments allow different SDCs to be used during post-synthesis STA and post-fit STA. It is also possible for an SDC to check the current snapshot through is_post_syn_sta to determine the appropriate commands to use, as shown in the following example:

if {[is_post_syn_sta]} {
	puts "In post syn sta!"
}