llvm-offload-binary - LLVM Offload Binary Packager

SYNOPSIS

llvm-offload-binary [options] [input files…]

DESCRIPTION

llvm-offload-binary is a utility for bundling multiple device object files into a single binary container. The resulting binary can then be embedded into the host section table to form a fat binary containing offloading code for different targets. Conversely, it can also extract previously bundled device images.

The binary format begins with the magic bytes 0x10FF10AD, followed by a version and size. Each binary contains its own header, allowing tools to locate offloading sections even when merged by a linker. Each offload entry includes metadata such as the device image kind, producer kind, and key-value string metadata. Multiple offloading images are concatenated to form a fat binary.

EXAMPLE

# Package multiple device images into a fat binary:
$ llvm-offload-binary -o out.bin \
      --image=file=input.o,triple=nvptx64,arch=sm_70

# Extract a matching image from a fat binary:
$ llvm-offload-binary in.bin \
      --image=file=output.o,triple=nvptx64,arch=sm_70

# Extract and archive images into a static library:
$ llvm-offload-binary in.bin --archive -o libdevice.a

OPTIONS

--archive

When extracting from an input binary, write all extracted images into a static archive instead of separate files.

--image=<<key>=<value>,...>

Specify a set of arbitrary key-value arguments describing an image. Commonly used optional keys include arch (e.g. sm_70 for CUDA) and triple (e.g. nvptx64-nvidia-cuda).

-o <file>

Write output to <file>. When bundling, this specifies the fat binary filename. When extracting, this specifies the archive or output file destination.

--help, -h

Display available options. Use --help-hidden to show hidden options.

--help-list

Display a list of all options. Use --help-list-hidden to show hidden ones.

--version

Display the version of the llvm-offload-binary executable.

@<FILE>

Read command-line options from response file <FILE>.

BINARY FORMAT

The binary format is marked by the magic bytes 0x10FF10AD, followed by a version number. Each created binary contains its own header. This allows tools to locate offloading sections even after linker operations such as relocatable linking. Conceptually, this binary format is a serialization of a string map and an image buffer.

Table 1 Offloading Binary Header

Type	Identifier	Description
uint8_t	magic	The magic bytes for the binary format (0x10FF10AD)
uint32_t	version	Version of this format (currently version 1)
uint64_t	size	Size of this binary in bytes
uint64_t	entry offset	Absolute offset of the offload entries in bytes
uint64_t	entry size	Size of the offload entries in bytes

Each offload entry describes a bundled image along with its associated metadata.

Table 2 Offloading Entry Table

Type	Identifier	Description
uint16_t	image kind	The kind of the device image (e.g. bc, cubin)
uint16_t	offload kind	The producer of the image (e.g. openmp, cuda)
uint32_t	flags	Generic flags for the image
uint64_t	string offset	Absolute offset of the string metadata table
uint64_t	num strings	Number of string entries in the table
uint64_t	image offset	Absolute offset of the device image in bytes
uint64_t	image size	Size of the device image in bytes

The entry table refers to both a string table and the raw device image itself. The string table provides arbitrary key-value metadata.

Table 3 Offloading String Entry

Type	Identifier	Description
uint64_t	key offset	Absolute byte offset of the key in the string table
uint64_t	value offset	Absolute byte offset of the value in the string table

The string table is a collection of null-terminated strings stored in the image. Offsets allow string entries to be interpreted as key-value pairs, enabling flexible metadata such as architecture or target triple.

The enumerated values for image kind and offload kind are:

Table 4 Image Kind

Name	Value	Description
IMG_None	0x00	No image information provided
IMG_Object	0x01	The image is a generic object file
IMG_Bitcode	0x02	The image is an LLVM-IR bitcode file
IMG_Cubin	0x03	The image is a CUDA object file
IMG_Fatbinary	0x04	The image is a CUDA fatbinary file
IMG_PTX	0x05	The image is a CUDA PTX file

Table 5 Offload Kind

Name	Value	Description
OFK_None	0x00	No offloading information provided
OFK_OpenMP	0x01	The producer was OpenMP offloading
OFK_CUDA	0x02	The producer was CUDA
OFK_HIP	0x03	The producer was HIP
OFK_SYCL	0x04	The producer was SYCL

SEE ALSO

clang(1), llvm-objdump(1)