This PR is one of the many PRs in the SYCL upstreaming effort focusing
on device code linking during the SYCL offload compilation process. RFC:
https://discourse.llvm.org/t/rfc-offloading-design-for-sycl-offload-kind-and-spir-targets/74088
In this PR, we introduce a new tool that will be used to perform device
code linking for SYCL offload kind. It accepts SYCL device objects in
LLVM IR bitcode format and will generate a fully linked device object
that can then be wrapped and linked into the host object.
A primary use case for this tool is to perform device code linking for
objects with SYCL offload kind inside the clang-linker-wrapper. It can
also be invoked via clang driver as follows:
`clang --target=spirv64 --sycl-link input.bc`
Device code linking for SYCL offloading kind has a number of known
quirks that makes it difficult to use in a unified offloading setting.
Two of the primary issues are:
1. Several finalization steps are required to be run on the fully-linked
LLVM IR bitcode to gaurantee conformance to SYCL standards. This step is
unique to SYCL offloading compilation flow.
2. SPIR-V LLVM Translator tool is an extenal tool and hence SPIR-V IR
code generation cannot be done as part of LTO. This limitation will be
lifted once SPIR-V backend is available as a viable LLVM backend.
Hence, we introduce this new tool to provide a clean wrapper to perform
SYCL device linking.
Co-Author: Michael Toguchi
Thanks
---------
Signed-off-by: Arvind Sudarsanam <arvind.sudarsanam@intel.com>
Prefer using `llvm-spirv-<LLVM_VERSION_MAJOR>` tool (i.e.
`llvm-spirv-18`) over plain `llvm-spirv`. If the versioned tool is not
found in PATH, fall back to use the plain `llvm-spirv`.
An issue with the using `llvm-spirv` is that the one found in PATH might
be compiled against older LLVM version which could lead to crashes or
obscure bugs. For example, `llvm-spirv` distributed by Ubuntu links
against different LLVM version depending on the Ubuntu release (LLVM-10
in 20.04LTS, LLVM-13 in 22.04LTS).
Add support of linking files compiled into SPIR-V objects
using spirv-link.
Command line inteface examples:
clang --target=spirv64 test1.cl test2.cl
clang --target=spirv64 test1.cl -o test1.o
clang --target=spirv64 test1.o test2.cl -o test_app.out
This works independently from the SPIR-V generation method
(via an external tool or an internal backend) and applies
to either approach that is being used.
Differential Revision: https://reviews.llvm.org/D116266
This patch adds a toolchain (TC) for SPIR-V along with the
following changes in Driver and base ToolChain and Tool.
This is required to provide a mechanism in clang to bypass
SPIR-V backend in LLVM for SPIR-V until it lands in LLVM and
matures.
The SPIR-V code is generated by the SPIRV-LLVM translator tool
named 'llvm-spirv' that is sought in 'PATH'.
The compilation phases/actions should be bound for SPIR-V in
the meantime as following:
compile -> tools::Clang
backend -> tools::SPIRV::Translator
assemble -> tools::SPIRV::Translator
However, Driver’s ToolSelector collapses compile-backend-assemble
and compile-backend sequences to tools::Clang. To prevent this,
added new {use,has}IntegratedBackend properties in ToolChain and
Tool to which the ToolSelector reacts on, and which SPIR-V TC
overrides.
Linking of multiple input files is currently not supported but
can be added separately.
Differential Revision: https://reviews.llvm.org/D112410
Co-authored-by: Henry Linjamäki <henry.linjamaki@parmance.com>
Add a tool for constructing commands for translating LLVM IR to
SPIR-V.
Used by HIPSPV tool chain (D110618).
Reviewed By: bader
Differential Revision: https://reviews.llvm.org/D112404
