This patch adds an Offload Wrapper for the SYCL kind. This is an
essential step for SYCL offloading and the compilation flow. The usage
of offload wrapping is added to the clang-linker-wrapper tool.
Modifications:
Implemented `bundleSYCL()` function to handle SYCL image bundling.
Implemented `wrapSYCLBinaries()` function that is invoked from
clang-linker-wrapper.
SYCL Offload Wrapping uses specific data structures such as
`__sycl.tgt_device_image` and `__sycl.tgt_bin_desc`. Each SYCL image
maintains its own symbol table (unlike shared global tables in other
targets). Therefore, symbols are encoded explicitly during the offload
wrapping. Also, images refer to their own Offloading Entries arrays
unlike other targets.
The proposed `__sycl.tgt_device_image` uses Version 3 to differentiate
from images generated by Intel DPC++. The structure proposed in this
patch doesn't have fields deprecated in DPC++.
This needs to match the runtime plugin (currently in PR
[here](https://github.com/llvm/llvm-project/pull/158900)), and use the
recently-added `INTELGT` machine type which is correct for Intel GPU
images.
---------
Signed-off-by: Sarnie, Nick <nick.sarnie@intel.com>
The module currently stores the target triple as a string. This means
that any code that wants to actually use the triple first has to
instantiate a Triple, which is somewhat expensive. The change in #121652
caused a moderate compile-time regression due to this. While it would be
easy enough to work around, I think that architecturally, it makes more
sense to store the parsed Triple in the module, so that it can always be
directly queried.
For this change, I've opted not to add any magic conversions between
std::string and Triple for backwards-compatibilty purses, and instead
write out needed Triple()s or str()s explicitly. This is because I think
a decent number of them should be changed to work on Triple as well, to
avoid unnecessary conversions back and forth.
The only interesting part in this patch is that the default triple is
Triple("") instead of Triple() to preserve existing behavior. The former
defaults to using the ELF object format instead of unknown object
format. We should fix that as well.
Add manual ELF packaging for `spirv64-intel` images as there is no
SPIR-V linker available. This format will be expected by the runtime
plugin we will submit in the future and is compatible with the format we
already use downstream.
---------
Signed-off-by: Sarnie, Nick <nick.sarnie@intel.com>
Summary:
This patch unifies the existing offloading entires into a single section
called `llvm_offload_entires`. This lets us use a more unified
offloading infrastructure so that all targets share the same handling.
The effect is that people in the runtimes now need to check if the kind
is what they expect, but the expectation is that you can combine
multiple potential providers into a compile job. Doesn't fully work
yet because of other runtime issues, but some day. Mostly this helps the
future of liboffload where we want to handle different languages than
OpenMP.
Summary:
The previous offloading entry type did not fit the current use-cases
very well. This widens it and adds a version to prevent further
annoyances. It also includes the kind to better sort who's using it.
The first 64-bytes are reserved as zero so the OpenMP runtime can detect
the old format for binary compatibilitry.
Summary:
Previously, managed variables didn't work in rdc mode using the new
driver because we just didn't register them. This was previously ignored
because we didn't have enough space in the current struct format. This
patch amends that by just emitting a struct pair for the two variables
and using the single pointer.
In the future, a more extensible entry format would be nice, but that
can be done later.
Summary:
For our offloading entries, we currently store all the string names of
kernels that the runtime will need to load from the target executable.
These are available via pointer in the `__tgt_offload_entry` struct,
however this makes it difficult to obtain from the object itself. This
patch simply puts the strings in a named section so they can be easily
queried.
The motivation behind this is that when the linker wrapper is doing
linking, it wants to know which kernels the host executable is calling.
We *could* get this already via the `.relaomp_offloading_entires`
section and trawling through the string table, but that's quite annoying
and not portable. The follow-up to this should be to make the linker
wrapper get a list of all used symbols the device link job should count
as "needed" so we can handle static linking more directly.
This patch moves utilities from
`offload/plugins-nextgen/amdgpu/utils/UtilitiesRTL.h` to
`llvm/Frontend/Offloading/Utility.h` to be reused by
other projects.
Concretely the following changes were made:
- Rename `KernelMetaDataTy` to `AMDGPUKernelMetaData`.
- Remove unused fields `KernelObject`, `KernelSegmentSize`,
`ExplicitArgumentCount` and `ImplicitArgumentCount` from
`AMDGPUKernelMetaData`.
- Return the produced error if `ELFObj.sections()` failed instead of
using `cantFail`.
- Added `AGPRCount` field to `AMDGPUKernelMetaData`.
- Added a default invalid value to all the fields in
`AMDGPUKernelMetaData`.
Summary:
These entires are generic for offloading with the new driver now. Having
the `omp` prefix was a historical artifact and is confusing when used
for CUDA. This patch just renames them for now, future patches will
rework the binary format to make it more common.
Summary:
The PTX language rejects globals with `.` in the name. We need to change
the global name if we are targeting NVPTX to prevent the toolchain from
complaining.
Summary:
The offloading wrapper is a object file that contains code necessary to
register offloading entries for the given runtime. Currently, we
expected only one of these to be present when we make the final
executable. However, in the case of redistributable linking with `-r` we
can end up with multiple of these being generated before finally
creating the executable.
This patch simply changes the defintiions of these globals to be
mergable. This allows multiples of these to participate in a single link
job. For ELF, we just make the dummy variable internal and used so it
sets up the section as expected. For COFF we make the entries weak_odr
so they merge to a single symbol
This patch moves `clang/tools/clang-linker-wrapper/OffloadWrapper.*` to
`llvm/Frontend/Offloading` allowing them to be re-utilized by other
projects.
Additionally, it makes minor modifications to the API to make it more
flexible.
Concretely:
- The `wrap*` methods now have additional arguments `EntryArray`,
`Suffix` and `EmitSurfacesAndTextures` to specify some additional options.
- The `EntryArray` is now constructed by the caller. This change is needed to
enable JIT compilation, as ORC doesn't fully support `__start_` and `__stop_`
symbols. Thus, to JIT the code, the `EntryArray` has to be constructed explicitly in the IR.
- The `Suffix` field is used when emitting the descriptor, registration
methods, etc, to make them more readable. It is empty by default.
- The `EmitSurfacesAndTextures` field controls whether to emit surface
and texture registration code, as those functions were removed from `CUDART`
in CUDA 12. It is true by default.
- The function `getOffloadingEntryInitializer` was added to help create
the `EntryArray`, as it returns the constant initializer and not a global
variable.
Summary:
This patch adds support for registering texture / surface variables from
CUDA / HIP. Additionally, we now properly track the `extern` and `const`
flags that are also used in these runtime functions.
This does not implement the `managed` variables yet as those seem to
require some extra handling I'm not familiar with. The issue is that the
current offload entry isn't large enough to carry size and alignment
information along with an extra global.
Summary:
This patch provides the initial support to allow handling the new
driver's offloading entries. Normally, the ELF target can emit varibles
at C-identifier named sections and the linker will provide a pointer to
the section. For COFF target, instead the linker merges sections
containing a `$` in alphabetical order. We thus can emit these variables
at sections and then emit two variables that are guaranteed to be sorted
before and after the others to traverse it. Previous patches
consolidated the handling of offloading entries so that this patch more
easily can handle mapping them to the appropriate section.
Ideally, the only remaining step to allow the new driver to run on
Windows targets is to accurately map the following `ld.lld` arguments to
their `llvm-link` equivalents. These are used inside the linker-wrapper,
so we should simply need to remap the arguments to the same
functionality if possible.
```
-o, -output
-l, --library
-L, --library-path
-v, --version
-rpath
-whole-archive, -no-whole-archive
```
I have not tested this at runtime as I do not have access to a windows
machine.
This patch was adapted from some initial efforts in
https://reviews.llvm.org/D137470.
Summary:
This patch is a simple refactoring of code out of the linker wrapper
into a common location. The main motivation behind this change is to
make it easier to change the handling in the future to accept a triple
to be used to emit entries that function on that target.
Summary:
This patch is a first step to remove dependencies on the OpenMPIRBuilder
for creating generic offloading entries. This patch changes no
functionality and merely moves the code around. In the future the
interface will be changed to allow for more code re-use in the
registration and creation of offloading entries as well as a more
generic interface for CUDA, HIP, OpenMP, and SYCL(?). Doing this as a
first step to reduce the noise involved in the functional changes.
