Vitis Compiler General Options - 2021.2 English

Vitis Unified Software Platform Documentation: Application Acceleration Development (UG1393)

Document ID
UG1393
ft:locale
English (United States)
Release Date
2021-12-15
Version
2021.2 English

The Vitis compiler supports many options for both the compilation process and the linking process. These options provide a range of features, and some apply specifically to compile or link, while others can be used, or are required for both compile and link.

Tip: All Vitis compiler options can be specified in a configuration file for use with the --config option, as discussed in the Vitis Compiler Configuration File. For example, the --platform option can be specified in a configuration file without a section head using the following syntax:
platform=xilinx_u200_xdma_201830_2

--advanced

Applies to
Compile and link

Specify parameters and properties for use by the v++ command. See --advanced Options for more information.

--board_connection

Applies to
Compile and link
--board_connection

Specifies a dual in-line memory module (DIMM) board file for each DIMM connector slot. The board is specified using the Vendor:Board:Name:Version (vbnv) attribute of the DIMM card as it appears in the board repository.

For example:

<DIMM_connector>:<vbnv_of_DIMM_board>

-c | --compile

Applies to
Compile
--compile

Required for compilation, but mutually exclusive with --link and --package. Run v++ -c to generate XO files from kernel source files.

--clock

Applies to
Link

Provide a method for assigning clocks to kernels during the linking process. See --clock Options for more information.

--config

Applies to
Compile, link, and package
--config <config_file> ...

Specifies a configuration file containing v++ command options. The configuration file can be used to capture compilation, linking, or packaging strategies, that can be easily reused by referring to the config file on the v++ command line. In addition, the config file allows the v++ command line to be shortened to include only the options that are not specified in the config file. Refer to the Vitis Compiler Configuration File for more information.

Tip: Multiple configuration files can be specified on the v++ command line. A separate --config switch is required for each file used. For example:
v++ -l --config cfg_connectivity.cfg --config cfg_vivado.cfg ...

--connectivity

Applies to
Link

Used to specify important architectural details of the device binary during the linking process. See --connectivity Options for more information.

--custom_script

Applies to
Compile and link
--custom_script <kernel_name>:<file_name>

This option lets you specify custom Tcl scripts to be used in the build process during compilation or linking. Use with the --export_script option to create, edit, and run the scripts to customize the build process.

When used with the v++ --compile command, this option lets you specify a custom HLS script to be used when compiling the specified kernel. The script lets you modify or customize the Vitis HLS tool. Use the --export_script option to extract a Tcl script Vitis HLS uses to compile the kernel, modify the script as needed, and resubmit using the --custom_script option to better manage the kernel build process.

The argument lets you specify the kernel name, and path to the Tcl script to apply to that kernel. For example:
v++ -c -k kernel1 -export_script ...
*** Modify the exported script to customize in some way, then resubmit. ****
v++ -c --custom_script kernel1:./kernel1.tcl ...

When used with the v++ --link command for the hardware build target (-t hw), this option lets you specify the absolute path to an edited run_script_map.dat file. This file contains a list of steps in the build process, and Tcl scripts that are run by the Vitis and Vivado tools during those steps. You can edit run_script_map.dat to specify custom Tcl scripts to run at those steps in the build process. You must use the following steps to customize the Tcl scripts:

  1. Run the build process specifying the --export_script option as follows:
    v++ -t hw -l -k kernel1 -export_script ...
  2. Copy the Tcl scripts referenced in the run_script_map.dat file for any of the steps you want to customize. For example, copy the Tcl file specified for the synthesis run, or the implementation run. You must copy the file to a separate location, outside of the project build structure.
  3. Edit the Tcl script to add or modify any of the existing commands to create a new custom Tcl script.
  4. Edit the run_script_map.dat file to point a specific implementation step to the new custom script.
  5. Relaunch the build process using the --custom_script option, specifying the absolute path to the run_script_map.dat file as shown below:
    v++ -t hw -l -k kernel1 -custom_script /path/to/run_script_map.dat
Important: When editing a custom synthesis run script, you must either comment out the lines related to the dont_touch.xdc file, or edit the lines to point to a new user-specified dont_touch.xdc file. The specific lines to comment or edit are shown below:
read_xdc dont_touch.xdc
set_property used_in_implementation false [get_files dont_touch.xdc]

The synthesis run returns an error related to a missing dont_touch.xdc file if this is not done.

--debug

Applies to
Link

Specify debug IP core insertion in the device binary (.xclbin). See --debug Options for more information.

-D | --define

Applies to
Compile and link
--define <arg>

Valid macro name and definition pair: <name>=<definition>.

Predefine name as a macro with definition. This option is passed to the v++ pre-processor.

--export_script

Applies to
Compile and link
--export_script

This option runs the build process up to the point of exporting a script file, or list of script files, and then stops execution. The build process must be completed using the --custom_script option. This lets you edit the exported script, or list of scripts, and then rerun the build using your custom scripts.

When used with the v++ --compile command, this option exports a Tcl script for the specified kernel, <kernel_name>.tcl, that can be used to execute Vitis HLS, but stops the build process before actually launching the HLS tool. This lets you interrupt the build process to edit the generated Tcl script, and then restart the build process using the --custom_script option, as shown in the following example:

v++ -c -k kernel1 -export_script ...
Tip: This option is not supported for software emulation (–t sw_emu) of OpenCL kernels.

When used with the v++ --link command for the hardware build target (-t hw), this option exports a run_script_map.dat file in the current directory. This file contains a list of steps in the build process, and Tcl scripts that are run by the Vitis and Vivado tools during those steps. You can edit the specified Tcl scripts, customizing the build process in those scripts, and relaunch the build using the --custom_script option. Export the run_script_map.dat file using the following command:

v++ -t hw -l -k kernel1 -export_script ...

--from_step

Applies to
Compile and link
--from_step <arg>

Specifies a step name for the Vitis compiler build process, to start the build process from that step. If intermediate results are available, the link process fast forwards and begins execution at the named step if possible. This allows you to run the build through a --to_step, and then resume the build process at the --from_step, after interacting with your project in some method. You can use the --list_step option to determine the list of valid steps.

Important: The --from_step and --to_step options are sequential build options that require you to use the same project directory when launching the Vitis compiler using --from_step to resume the build as you specified when using --to_step to start the build.

For example:

v++ --link --from_step vpl.update_bd

-g

Applies to
Compile and link
-g

Generates code for debugging the kernel during software emulation. Using this option adds features to facilitate debugging the kernel as it is compiled.

For example:

v++ -g ...

-h | --help

-h

Prints the help contents for the v++ command. For example:

v++ -h

--hls

Applies to
Compile

Specify options for the Vitis HLS synthesis process during kernel compilation. See --hls Options for more information.

-I | --include

Applies to
Compile and link
--include <arg>

Add the specified directory to the list of directories to be searched for header files. This option is passed to the Vitis compiler pre-processor.

<input_file>

Applies to
Compile and link
<input_file1> <input_file2> ...

Specifies an OpenCL or C/C++ kernel source file for v++ compilation, or Xilinx object (XO) files for v++ linking.

For example:

v++ -l kernel1.xo kernelRTL.xo ...

--interactive

Applies to
Compile and link
--interactive [ impl ]

v++ configures the needed environment and launches the Vivado tool with the implementation project.

Because you are interactively launching the Vivado tool, the linking process is stopped after the vpl step, which is the equivalent of using the --to_step vpl option in your v++ command.

When you are done interactively working with the Vivado tool, and you save the design checkpoint (DCP), you can resume the Vitis compiler linking process using the v++ --from_step rtdgen, or use the --reuse_impl or --reuse_bit options to read in the implemented DCP file or bitstream.

For example:

v++ --interactive impl
## Interactively use the Vivado tool
v++ --from_step rtdgen

-k | --kernel

Applies to
Compile
--kernel <arg>

Compile only the specified kernel from the input file. Only one -k option is allowed per v++ command. Valid values include the name of the kernel to be compiled from the input .cl or .c/.cpp kernel source code.

This is required for C/C++ kernels, but is optional for OpenCL kernels. OpenCL uses the kernel keyword to identify a kernel. For C/C++ kernels, you must identify the kernel by -k or --kernel.

When an OpenCL source file is compiled without the -k option, all the kernels in the file are compiled. Use -k to target a specific kernel.

For example:

v++ -c --kernel vadd

--kernel_frequency

Important: This command is used for legacy platforms with changeable clocks, and is replaced by the --clock Options command for newer platform shells. Refer to Managing Clock Frequencies for more information.
Applies to
Compile and link
--kernel_frequency <freq> | <clockID>:<freq>[<clockID>:<freq>]

Specifies a user-defined clock frequency (in MHz) for the kernel, overriding the default clock frequency defined on the hardware platform. The <freq> specifies a single frequency for kernels with only a single clock, or can be used to specify the <clockID> and the <freq> for kernels that support two clocks.

The syntax for overriding the clock on a platform with only one kernel clock, is to simply specify the frequency in MHz:

v++ --kernel_frequency 300

To override a specific clock on a platform with two clocks, specify the clock ID and frequency:

v++ --kernel_frequency 0:300

To override both clocks on a multi-clock platform, specify each clock ID and the corresponding frequency. For example:

v++ --kernel_frequency 0:300|1:500

-l | --link

--link

This is a required option for the linking process, which follows compilation, but is mutually exclusive with --compile or --package. Run v++ in link mode to link XO input files and generate an xclbin output file.

--linkhook

Applies to
Link

Lets you customize the build process for the device binary by specifying Tcl scripts to be run at specific steps in the implementation flow. See --linkhook Options for more information.

--list_steps

Applies to
Compile and link
--list_steps

List valid run steps for a given target. This option returns a list of steps that can be used in the --from_step or --to_step options. The command must be specified with the following options:

  • -t | --target [sw_emu | hw_emu | hw ]:
  • [ --compile | --link ]: Specifies the list of steps from either the compile or link process for the specified build target.

For example:

v++ -t hw_emu --link --list_steps

--log_dir

Applies to
Compile and link
--log_dir <dir_name>

Specifies a directory to store log files into. If --log_dir is not specified, the tool saves the log files to ./_x/logs. Refer to Output Directories of the v++ Command for more information.

For example:

v++ --log_dir /tmp/myProj_logs ...

--message_rules

Applies to
Compile and link
--message-rules <file_name>

Specifies a message rule file with rules for controlling messages. Refer to Using the Message Rule File for more information.

For example:

v++ --message_rules ./minimum_out.mrf ...

--no_ip_cache

Applies to
Compile and link
--no_ip_cache

Disables the IP cache for out-of-context (OOC) synthesis for Vivado Synthesis. Disabling the IP cache repository requires the tool to regenerate the IP synthesis results for every build, and can increase the build time. However, it also results in a clean build, eliminating earlier results for IP in the design.

For example:

v++ --no_ip_cache ...

-O | --optimize

Applies to
Compile and link
--optimize <arg>

This option specifies the optimization level of the Vivado implementation results. Valid optimization values include the following:

  • 0: Default optimization. Reduces compilation time.
  • 1: Optimizes to reduce power consumption by running Vivado implementation strategy Power_DefaultOpt. This takes more time to build the design.
  • 2: Optimizes to increase kernel speed. This option increases build time, but also improves the performance of the generated kernel by adding the PHYS_OPT_DESIGN step to implementation.
  • 3: This optimization provides the highest level performance in the generated code, but compilation time can increase considerably. This option specifies retiming during synthesis, and enables both PHYS_OPT_DESIGN and POST_ROUTE_PHYS_OPT_DESIGN during implementation.
  • s: Optimizes the design for size. This reduces the logic resources of the device used by the kernel by running the Area_Explore implementation strategy.
  • quick: Reduces Vivado implementation time, but can reduce kernel performance, and increases the resources used by the kernel. This enables the Flow_RuntimeOptimized strategy for both synthesis and implementation.

For example:

v++ --link --optimize 2

-o | --output

Applies to
Compile and link
-o <output_name>

Specifies the name of the output file generated by the v++ command. The compilation (-c) process output name must end with the XO file suffix, for Xilinx object file. The linking (-l) process output file must end with the xclbin file suffix, for Xilinx executable binary.

For example:

v++ -o krnl_vadd.xo

If --o or --output are not specified, the output file names default to the following:

  • a.o for compilation.
  • a.xclbin for linking.

-p | --package

Applies to
Package

Specify options for the Vitis compiler to package your design for either running emulation or running on hardware. See --package Options for more information.

-f | --platform

Applies to
Compile and link
--platform <platform_name>

Specifies the name of a supported acceleration platform as specified by the $PLATFORM_REPO_PATHS environment variable, or the full path to the platform .xpfm file. For a list of supported platforms for the release, see the Vitis Software Platform Release Notes.

This is a required option for both compilation and linking, to define the target Xilinx platform of the build process. The --platform option accepts either a platform name, or the path to a platform file xpfm, using the full or relative path.

Important: The specified platform and build targets for compiling and linking must match. The --platform and -t options specified when the XO file is generated by compilation, must be the --platform and -t used during linking. For more information, see platforminfo Utility.

For example:

v++ --platform xilinx_u200_xdma_201830_2 ...
Tip: All Vitis compiler options can be specified in a configuration file for use with the --config option. For example, the platform option can be specified in a configuration file without a section head using the following syntax:
platform=xilinx_u200_xdma_201830_2

--profile

Applies to
Compile and link

Specify options to configure the Xilinx runtime environment to capture application performance information. See --profile Options for more information.

--remote_ip_cache

Applies to
Compile and link
--remote_ip_cache <dir_name>

Specifies the location of the remote IP cache directory for Vivado Synthesis to use during out-of-context (OOC) synthesis of IP. OOC synthesis lets the Vivado synthesis tool reuse synthesis results for IP that have not been changed in iterations of a design. This can reduce the time required to build your .xclbin files, due to reusing synthesis results.

When the --remote_ip_cache option is not specified the IP cache is written to the current working directory from which v++ was launched. You can use this option to provide a different cache location, used across multiple projects for instance.

For example:

v++ --remote_ip_cache /tmp/IP_cache_dir ...

--report_dir

Applies to
Compile and link
--report_dir <dir_name>

Specifies a directory to store report files into. If --report_dir is not specified, the tool saves the report files to ./_x/reports. Refer to Output Directories of the v++ Command for more information.

For example:

v++ --report_dir /tmp/myProj_reports ...

-R | --report_level

Applies to
Compile and link
--report_level <arg>

Valid report levels: 0, 1, 2, estimate.

These report levels have mappings kept in the optMap.xml file. You can override the installed optMap.xml to define custom report levels.

  • -R0 specification turns off all intermediate design checkpoint (DCP) generation during Vivado implementation. Turns on post-route timing report generation.
  • The -R1 specification includes everything from -R0, plus report_failfast pre-opt_design, report_failfast post-opt_design, and enables all intermediate DCP generation.
  • The -R2 specification includes everything from -R1, plus report_failfast post-route_design.
  • The -Restimate specification forces Vitis HLS to generate a design.xml file if it does not exist and then generates a System Estimate report, as described in System Estimate Report.
    Tip: This option is useful for the software emulation build (-t sw_emu), when design.xml is not generated by default.

For example:

v++ -R2 ... 

--reuse_bit

--reuse_bit <arg>
Applies to
Link

Specifies the path and file name of generated bitstream file (.bit) to use when generating the device binary (xclbin) file. As described in Using -to_step and Launching Vivado Interactively, you can specify the --to_step option to interrupt the Vitis build process and manually place and route a synthesized design to generate the bitstream.

Important: The --reuse_bit option is a sequential build option that requires you to use the same project directory when resuming the Vitis compiler with --reuse_bit that you specified when using --to_step to start the build.

For example:

v++ --link --reuse_bit ./project.bit

--reuse_impl

--reuse_impl <arg>
Applies to
Link

Specifies the path and file name of an implemented design checkpoint (DCP) file to use when generating the device binary (xclbin) file. The link process uses the specified implemented DCP to extract the FPGA bitstream and generates the xclbin. You can manually edit theVivado project created by a previously completed Vitis build, or specify the --to_step option to interrupt the Vitis build process and manually place and route a synthesized design, for instance. This allows you to work interactively with Vivado Design Suite to change the design and use DCP in the build process.

Important: The --reuse_impl option is an incremental build option that requires you to use the same project directory when resuming the Vitis compiler with --reuse_impl that you specified when using --to_step to start the build.

For example:

v++ --link --reuse_impl ./manual_design.dcp

-s | --save-temps

Applies to
Compile and link
--save-temps

Directs the v++ command to save intermediate files/directories created during the compilation and link process. Use the --temp_dir option to specify a location to write the intermediate files to.

Tip: This option is useful for debugging when you encounter issues in the build process.

For example:

v++ --save_temps ...

-t | --target

Applies to
Compile and link
-t [ sw_emu | hw_emu | hw ]

Specifies the build target, as described in Build Targets. The build target determines the results of the compilation and linking processes. You can choose to build an emulation model for debug and test, or build the actual system to run in hardware. The build target defaults to hw if -t is not specified.

Important: The specified platform and build targets for compiling and linking must match. The --platform and -t options specified when the XO file is generated by compilation must be the --platform and -t used during linking.

The valid values are:

  • sw_emu: Software emulation
  • hw_emu: Hardware emulation
  • hw: Hardware

For example:

v++ --link -t hw_emu

--temp_dir

Applies to
Compile and link
--temp_dir <dir_name>

This allows you to manage the location where the tool writes temporary files created during the build process. The temporary results are written by the v++ compiler, and then removed, unless the --save-temps option is also specified.

If --temp_dir is not specified, the tool saves the temporary files to ./_x/temp. Refer to Output Directories of the v++ Command for more information.

For example:

v++ --temp_dir /tmp/myProj_temp ...

--to_step

Applies to
Compile and link
--to_step <arg>

Specifies a step name, for either the compile or link process, to run the build process through that step. You can use the --list_step option to determine the list of valid compile or link steps.

The build process terminates after completing the named step. At this time, you can interact with the build results. For example, manually accessing the HLS project or the Vivado Design Suite project to perform specific tasks before returning to the build flow, launch the v++ command with the --from_step option.

Important: The --to_step and --from_step options are incremental build options that require you to use the same project directory when launching the Vitis compiler using --from_step to resume the build as you specified when using --to_step to start the build.

You must also specify --save-temps when using --to_step to preserve the temporary files required by the Vivado tools. For example:

v++ --link --save-temps --to_step vpl.update_bd

--trace_memory

Applies to
Link

The --trace_memory command has been deprecated and replaced by --profile.trace_memory. See --profile Options for more information.

-v | --version

-v

Prints the version and build information for the v++ command. For example:

v++ -v

--vivado

Applies to
Link

Specify properties and parameters to configure the Vivado synthesis and implementation environment prior to building the device binary. See --vivado Options for more information.

--user_board_repo_paths

Applies to
Compile and link
--user_board_repo_paths

Specifies an existing user board repository for DIMM board files. This value is pre-pended to the board_part_repo_paths property of the Vivado project.

--user_ip_repo_paths

Applies to
Compile and link
--user_ip_repo_paths <repo_dir>

Specifies the directory location of one or more user IP repository paths to be searched first for IP used in the kernel design. This value is appended to the start of the ip_repo_paths used by the Vivado tool to locate IP cores. IP definitions from these specified paths are used ahead of IP repositories from the hardware platform (.xsa) or from the Xilinx IP catalog.

Tip: Multiple --user_ip_repo_paths can be specified on the v++ command line.

The following lists show the priority order in which IP definitions are found during the build process, from high to low. Note that all of these entries can possibly include multiple directories in them.

  • For the system hardware build (-t hw):
    1. IP definitions from --user_ip_repo_paths.
    2. Kernel IP definitions (vpl --iprepo switch value).
    3. IP definitions from the IP repository associated with the platform.
    4. IP cache from the installation area (for example, <Install_Dir>/Vitis/2019.2/data/cache/).
    5. Xilinx IP catalog from the installation area (for example, <Install_Dir>/Vitis/2019.2/data/ip/)
  • For the hardware emulation build (-t hw_emu):
    1. IP definitions and User emulation IP repository from --user_ip_repo_paths.
    2. Kernel IP definitions (vpl --iprepo switch value).
    3. IP definitions from the IP repository associated with the platform.
    4. IP cache from the installation area (for example, <Install_Dir>/Vitis/2019.2/data/cache/).
    5. $::env(XILINX_VITIS)/data/emulation/hw_em/ip_repo
    6. $::env(XILINX_VIVADO)/data/emulation/hw_em/ip_repo
    7. Xilinx IP catalog from the installation area (for example, <Install_Dir>/Vitis/2019.2/data/ip/)

For example:

v++ --user_ip_repo_paths ./myIP_repo ...