BuildHLS

BuildHLS.cmake provides CMake functions for compiling HLS C++ kernels using Vitis HLS. It is automatically included by SlashTools, so you do not need to include it separately.

build_hls()

Compiles a single HLS kernel from a C++ source file and configuration.

build_hls(
  TARGET  <target_name>
  CPP     <source_file>
  CFG     <config_file>
  DEVICE  <part_string>
  [OUT_DIR <output_directory>]
)

Parameters

TARGET (required): CMake target name for this kernel build.
CPP (required): Path to the HLS C++ source file.
CFG (required): Path to the Vitis HLS configuration file (.cfg).
DEVICE (required): FPGA part string, e.g. xcv80-lsva4737-2MHP-e-S.
OUT_DIR (optional): Output directory. Defaults to CMAKE_CURRENT_BINARY_DIR.

Output Properties

After the target is created, two properties are set on it:

HLS_BUILD_DIR: The build directory containing HLS outputs.
HLS_COMPONENT_XML: Path to the generated component.xml file. This is the input for add_vbin().

The same values are also exported as ${TARGET}_BUILD_DIR and ${TARGET}_COMPONENT_XML in the calling scope.

build_hls_dir()

Compiles multiple HLS kernels from a directory containing paired <name>.cpp and <name>.cfg files.

build_hls_dir(
  TARGET      <target_name>
  ROOT        <directory>
  DEVICE      <part_string>
  KERNELS     <kernel_names...>
  [OUT_DIR     <output_directory>]
  [OUT_IP_REPO <variable_name>]
  [OUT_KERNELS <variable_name>]
)

Parameters

TARGET (required): Umbrella CMake target name. Individual kernel targets are created as ${TARGET}_${kernel_name}.
ROOT (required): Directory containing kernel source files. For each name listed in KERNELS, the directory must contain <name>.cpp and <name>.cfg.
DEVICE (required): FPGA part string.
KERNELS (required): List of kernel names to compile (without file extensions).
OUT_DIR (optional): Output directory. Defaults to ${CMAKE_CURRENT_BINARY_DIR}/${TARGET}.
OUT_IP_REPO (optional): Variable name to receive the IP repository output path.
OUT_KERNELS (optional): Variable name to receive the list of component.xml paths for all compiled kernels. Pass this to add_vbin(KERNELS ...).

build_hls_clean()

Creates a CMake target that removes HLS build artefacts.

build_hls_clean(
  TARGET  <target_name>
  DEVICE  <part_string>
  [ROOT   <directory>]
  [EXTRA_GLOBS <patterns...>]
)

Parameters

TARGET (required): Name for the clean target.
DEVICE (required): Part string, used to match build_*.${DEVICE} directories.
ROOT (optional): Directory to clean. Defaults to CMAKE_CURRENT_LIST_DIR.
EXTRA_GLOBS (optional): Additional glob patterns to remove.

The generated clean target removes: build directories, log files, .Xil directories, CMake cache files, and any patterns specified via EXTRA_GLOBS.

HLS Configuration File Format

Each kernel requires a .cfg file for Vitis HLS. Example (increment.cfg):

part=xcv80-lsva4737-2MHP-e-S

[hls]
flow_target=vivado

syn.top=increment
syn.file=increment.cpp
clock=4ns

package.output.format=ip_catalog
package.output.syn=false

part: The FPGA part string for the V80 board.
syn.top: Top-level function name in the C++ source.
syn.file: Source file to compile.
clock: Target clock period (e.g. 4ns = 250 MHz).
package.output.format: Must be ip_catalog for the SLASH linker.
package.output.syn: Set to false to defer RTL synthesis to the linker.

Example

A complete CMakeLists.txt using all three functions:

set(DEVICE "xcv80-lsva4737-2MHP-e-S")

build_hls_dir(
  TARGET      hls
  ROOT        "${CMAKE_CURRENT_SOURCE_DIR}/hls"
  DEVICE      "${DEVICE}"
  KERNELS     increment accumulate
  OUT_KERNELS _KERNELS
)

add_vbin(TARGET "my_design_hw" PLATFORM "hw"
         CFG "${CMAKE_CURRENT_SOURCE_DIR}/config.cfg"
         KERNELS ${_KERNELS})

build_hls_clean(TARGET hls_clean DEVICE "${DEVICE}")

Build with:

cmake --build build --target hls            # compile all HLS kernels
cmake --build build --target my_design_hw   # link into a hardware vrtbin
cmake --build build --target hls_clean      # remove HLS build artefacts