[libc] Rework the GPU build to be a regular target (#81921)
Summary:
This is a massive patch because it reworks the entire build and
everything that depends on it. This is not split up because various bots
would fail otherwise. I will attempt to describe the necessary changes
here.
This patch completely reworks how the GPU build is built and targeted.
Previously, we used a standard runtimes build and handled both NVPTX and
AMDGPU in a single build via multi-targeting. This added a lot of
divergence in the build system and prevented us from doing various
things like building for the CPU / GPU at the same time, or exporting
the startup libraries or running tests without a full rebuild.
The new appraoch is to handle the GPU builds as strict cross-compiling
runtimes. The first step required
https://github.com/llvm/llvm-project/pull/81557 to allow the `LIBC`
target to build for the GPU without touching the other targets. This
means that the GPU uses all the same handling as the other builds in
`libc`.
The new expected way to build the GPU libc is with
`LLVM_LIBC_RUNTIME_TARGETS=amdgcn-amd-amdhsa;nvptx64-nvidia-cuda`.
The second step was reworking how we generated the embedded GPU library
by moving it into the library install step. Where we previously had one
`libcgpu.a` we now have `libcgpu-amdgpu.a` and `libcgpu-nvptx.a`. This
patch includes the necessary clang / OpenMP changes to make that not
break the bots when this lands.
We unfortunately still require that the NVPTX target has an `internal`
target for tests. This is because the NVPTX target needs to do LTO for
the provided version (The offloading toolchain can handle it) but cannot
use it for the native toolchain which is used for making tests.
This approach is vastly superior in every way, allowing us to treat the
GPU as a standard cross-compiling target. We can now install the GPU
utilities to do things like use the offload tests and other fun things.
Some certain utilities need to be built with
`--target=${LLVM_HOST_TRIPLE}` as well. I think this is a fine
workaround as we
will always assume that the GPU `libc` is a cross-build with a
functioning host.
Depends on https://github.com/llvm/llvm-project/pull/81557
GitOrigin-RevId: 47b7c91abe7af3133a591aa2e73fffa30826f986
diff --git a/libomptarget/CMakeLists.txt b/libomptarget/CMakeLists.txt
index 17e61d0..a74eff0 100644
--- a/libomptarget/CMakeLists.txt
+++ b/libomptarget/CMakeLists.txt
@@ -119,14 +119,7 @@
pythonize_bool(LIBOMPTARGET_OMPT_SUPPORT)
-# Check if this build supports the GPU libc.
-set(LIBC_GPU_SUPPORT FALSE)
-if("libc" IN_LIST LLVM_ENABLE_RUNTIMES AND (LIBC_GPU_BUILD OR
- LIBC_GPU_ARCHITECTURES))
- set(LIBC_GPU_SUPPORT TRUE)
-endif()
-
-set(LIBOMPTARGET_GPU_LIBC_SUPPORT ${LIBC_GPU_SUPPORT} CACHE BOOL
+set(LIBOMPTARGET_GPU_LIBC_SUPPORT ${LLVM_LIBC_GPU_BUILD} CACHE BOOL
"Libomptarget support for the GPU libc")
pythonize_bool(LIBOMPTARGET_GPU_LIBC_SUPPORT)
diff --git a/libomptarget/plugins-nextgen/common/CMakeLists.txt b/libomptarget/plugins-nextgen/common/CMakeLists.txt
index 8ae3ff2..085d443 100644
--- a/libomptarget/plugins-nextgen/common/CMakeLists.txt
+++ b/libomptarget/plugins-nextgen/common/CMakeLists.txt
@@ -73,8 +73,12 @@
find_library(llvmlibc_rpc_server NAMES llvmlibc_rpc_server
PATHS ${LIBOMPTARGET_LLVM_LIBRARY_DIR} NO_DEFAULT_PATH)
if(llvmlibc_rpc_server)
- target_link_libraries(PluginCommon PRIVATE llvmlibc_rpc_server)
+ target_link_libraries(PluginCommon PRIVATE ${llvmlibc_rpc_server})
target_compile_definitions(PluginCommon PRIVATE LIBOMPTARGET_RPC_SUPPORT)
+ # We may need to get the headers directly from the 'libc' source directory.
+ target_include_directories(PluginCommon PRIVATE
+ ${CMAKE_SOURCE_DIR}/../libc/utils/gpu/server
+ ${CMAKE_SOURCE_DIR}/../libc/include)
endif()
endif()
diff --git a/libomptarget/plugins-nextgen/common/src/RPC.cpp b/libomptarget/plugins-nextgen/common/src/RPC.cpp
index 54aced1..cb6a508 100644
--- a/libomptarget/plugins-nextgen/common/src/RPC.cpp
+++ b/libomptarget/plugins-nextgen/common/src/RPC.cpp
@@ -18,7 +18,8 @@
#if __has_include(<gpu-none-llvm/rpc_server.h>)
#include <gpu-none-llvm/rpc_server.h>
#elif defined(LIBOMPTARGET_RPC_SUPPORT)
-#include <rpc_server.h>
+// Just pull this out of the source if available.
+#include "rpc_server.h"
#endif
using namespace llvm;
diff --git a/libomptarget/test/lit.cfg b/libomptarget/test/lit.cfg
index 565556e..6c59060 100644
--- a/libomptarget/test/lit.cfg
+++ b/libomptarget/test/lit.cfg
@@ -180,8 +180,12 @@
def add_libraries(source):
if config.libomptarget_has_libc:
- return source + " " + config.llvm_library_dir + "/libcgpu.a " + \
- config.llvm_library_intdir + "/libomptarget.devicertl.a"
+ if config.libomptarget_current_target.startswith('nvptx'):
+ return source + " " + config.llvm_library_dir + "/libcgpu-nvptx.a " + \
+ config.llvm_library_intdir + "/libomptarget.devicertl.a"
+ elif config.libomptarget_current_target.startswith('amdgcn'):
+ return source + " " + config.llvm_library_dir + "/libcgpu-amdgpu.a " + \
+ config.llvm_library_intdir + "/libomptarget.devicertl.a"
return source + " " + config.llvm_library_intdir + "/libomptarget.devicertl.a"
# substitutions
