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

ID 683236
Date 12/19/2022
Public

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2.3.2.3. 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 Early Timing Analysis, 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 5.  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 (DNI) Synthesis Fitter, Signoff

Stage where constraints are processed

Synthesis through Fitter

Synthesis only

Fitter, Signoff

QSF assignment

RTL_SDC_FILE

SYN_SDC_FILE

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
Yes
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. You must note that a single SDC file can be shared between the post-synthesis STA and post-fit STA. In this case, the SDC can check the current snapshot through is_post_syn_sta to determine the appropriate commands to use.