[Openmp-commits] [openmp] [Libomptarget] Allow the CPU targets to be built without libffi (PR #77495)
Joseph Huber via Openmp-commits
openmp-commits at lists.llvm.org
Tue Jan 9 10:57:27 PST 2024
https://github.com/jhuber6 updated https://github.com/llvm/llvm-project/pull/77495
>From 8a2bd92a1ffc88cabca8631cb90ab1fc158a7c46 Mon Sep 17 00:00:00 2001
From: Joseph Huber <huberjn at outlook.com>
Date: Tue, 9 Jan 2024 10:38:50 -0600
Subject: [PATCH] [Libomptarget] Allow the CPU targets to be built without
libffi
Summary:
The CPU targets currently rely on `libffi` to invoke the "kernel"
functions. Previously we would not build these if this dependency was
not found. This patch copies th eapproach used for things like CUDA and
HSA to dynamically load this if it is not found.
The one sketchy thing this does is hard-code the default ABI for the
target. These are normally defined on a per-file basis in the FFI
source, so I had to fish out the expected values. We only use two types,
so ideally we will always be able to use the default ABI.
It's possible we could remove this dependency entirely in the future as
well.
---
.../Modules/LibomptargetGetDependencies.cmake | 48 +-------
.../plugins-nextgen/CMakeLists.txt | 115 +++++++++---------
.../generic-elf-64bit/dynamic_ffi/ffi.cpp | 65 ++++++++++
.../generic-elf-64bit/dynamic_ffi/ffi.h | 78 ++++++++++++
.../generic-elf-64bit/src/rtl.cpp | 5 +
5 files changed, 209 insertions(+), 102 deletions(-)
create mode 100644 openmp/libomptarget/plugins-nextgen/generic-elf-64bit/dynamic_ffi/ffi.cpp
create mode 100644 openmp/libomptarget/plugins-nextgen/generic-elf-64bit/dynamic_ffi/ffi.h
diff --git a/openmp/libomptarget/cmake/Modules/LibomptargetGetDependencies.cmake b/openmp/libomptarget/cmake/Modules/LibomptargetGetDependencies.cmake
index 8c93bd586799b8..bbf2b9836c7095 100644
--- a/openmp/libomptarget/cmake/Modules/LibomptargetGetDependencies.cmake
+++ b/openmp/libomptarget/cmake/Modules/LibomptargetGetDependencies.cmake
@@ -50,52 +50,8 @@ endif()
################################################################################
# Looking for libffi...
################################################################################
-find_package(PkgConfig)
-
-pkg_check_modules(LIBOMPTARGET_SEARCH_LIBFFI QUIET libffi)
-
-find_path (
- LIBOMPTARGET_DEP_LIBFFI_INCLUDE_DIR
- NAMES
- ffi.h
- HINTS
- ${LIBOMPTARGET_SEARCH_LIBFFI_INCLUDEDIR}
- ${LIBOMPTARGET_SEARCH_LIBFFI_INCLUDE_DIRS}
- PATHS
- /usr/include
- /usr/local/include
- /opt/local/include
- /sw/include
- ENV CPATH)
-
-# Don't bother look for the library if the header files were not found.
-if (LIBOMPTARGET_DEP_LIBFFI_INCLUDE_DIR)
- find_library (
- LIBOMPTARGET_DEP_LIBFFI_LIBRARIES
- NAMES
- ffi
- HINTS
- ${LIBOMPTARGET_SEARCH_LIBFFI_LIBDIR}
- ${LIBOMPTARGET_SEARCH_LIBFFI_LIBRARY_DIRS}
- PATHS
- /usr/lib
- /usr/local/lib
- /opt/local/lib
- /sw/lib
- ENV LIBRARY_PATH
- ENV LD_LIBRARY_PATH)
-endif()
-
-set(LIBOMPTARGET_DEP_LIBFFI_INCLUDE_DIRS ${LIBOMPTARGET_DEP_LIBFFI_INCLUDE_DIR})
-find_package_handle_standard_args(
- LIBOMPTARGET_DEP_LIBFFI
- DEFAULT_MSG
- LIBOMPTARGET_DEP_LIBFFI_LIBRARIES
- LIBOMPTARGET_DEP_LIBFFI_INCLUDE_DIRS)
-
-mark_as_advanced(
- LIBOMPTARGET_DEP_LIBFFI_INCLUDE_DIRS
- LIBOMPTARGET_DEP_LIBFFI_LIBRARIES)
+find_package(FFI QUIET)
+set(LIBOMPTARGET_DEP_LIBFFI_FOUND ${FFI_FOUND})
################################################################################
# Looking for CUDA...
diff --git a/openmp/libomptarget/plugins-nextgen/CMakeLists.txt b/openmp/libomptarget/plugins-nextgen/CMakeLists.txt
index af2e5ef770f7e3..882be3025003b0 100644
--- a/openmp/libomptarget/plugins-nextgen/CMakeLists.txt
+++ b/openmp/libomptarget/plugins-nextgen/CMakeLists.txt
@@ -19,71 +19,74 @@ add_subdirectory(common)
# - tmachine_libname: machine name to be appended to the plugin library name.
macro(build_generic_elf64 tmachine tmachine_name tmachine_libname tmachine_triple elf_machine_id)
if(CMAKE_SYSTEM_PROCESSOR MATCHES "${tmachine}$")
- if(LIBOMPTARGET_DEP_LIBFFI_FOUND)
-
- libomptarget_say("Building ${tmachine_name} NextGen offloading plugin.")
-
- # Define macro to be used as prefix of the runtime messages for this target.
- add_definitions("-DTARGET_NAME=${tmachine_name}")
+ # Define macro to be used as prefix of the runtime messages for this target.
+ add_definitions("-DTARGET_NAME=${tmachine_name}")
- # Define debug prefix. TODO: This should be automatized in the Debug.h but
- # it requires changing the original plugins.
- add_definitions(-DDEBUG_PREFIX="TARGET ${tmachine_name} RTL")
+ # Define debug prefix. TODO: This should be automatized in the Debug.h but
+ # it requires changing the original plugins.
+ add_definitions(-DDEBUG_PREFIX="TARGET ${tmachine_name} RTL")
- # Define macro with the ELF ID for this target.
- add_definitions("-DTARGET_ELF_ID=${elf_machine_id}")
+ # Define the macro with the ELF e_machine for this target.
+ add_definitions("-DTARGET_ELF_ID=${elf_machine_id}")
- # Define target regiple
- add_definitions("-DLIBOMPTARGET_NEXTGEN_GENERIC_PLUGIN_TRIPLE=${tmachine}")
+ # Define target triple
+ add_definitions("-DLIBOMPTARGET_NEXTGEN_GENERIC_PLUGIN_TRIPLE=${tmachine}")
- add_llvm_library("omptarget.rtl.${tmachine_libname}"
- SHARED
+ add_llvm_library("omptarget.rtl.${tmachine_libname}"
+ SHARED
- ${CMAKE_CURRENT_SOURCE_DIR}/../generic-elf-64bit/src/rtl.cpp
+ ${CMAKE_CURRENT_SOURCE_DIR}/../generic-elf-64bit/src/rtl.cpp
- ADDITIONAL_HEADER_DIRS
+ ADDITIONAL_HEADER_DIRS
${LIBOMPTARGET_INCLUDE_DIR}
- ${LIBOMPTARGET_DEP_LIBFFI_INCLUDE_DIR}
-
- LINK_LIBS
- PRIVATE
- PluginCommon
- ${LIBOMPTARGET_DEP_LIBFFI_LIBRARIES}
- ${OPENMP_PTHREAD_LIB}
-
- NO_INSTALL_RPATH
- )
-
- if ((OMPT_TARGET_DEFAULT) AND (LIBOMPTARGET_OMPT_SUPPORT))
- target_link_libraries("omptarget.rtl.${tmachine_libname}" PRIVATE OMPT)
- endif()
-
- if (LIBOMP_HAVE_VERSION_SCRIPT_FLAG)
- target_link_libraries("omptarget.rtl.${tmachine_libname}" PRIVATE
- "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/../exports")
- endif()
-
- # Install plugin under the lib destination folder.
- install(TARGETS "omptarget.rtl.${tmachine_libname}"
- LIBRARY DESTINATION "${OPENMP_INSTALL_LIBDIR}")
- set_target_properties("omptarget.rtl.${tmachine_libname}" PROPERTIES
- INSTALL_RPATH "$ORIGIN" BUILD_RPATH "$ORIGIN:${CMAKE_CURRENT_BINARY_DIR}/.."
- POSITION_INDEPENDENT_CODE ON
- CXX_VISIBILITY_PRESET protected)
-
- target_include_directories( "omptarget.rtl.${tmachine_libname}" PRIVATE
- ${LIBOMPTARGET_INCLUDE_DIR}
- ${LIBOMPTARGET_DEP_LIBFFI_INCLUDE_DIR})
- list(APPEND LIBOMPTARGET_TESTED_PLUGINS "omptarget.rtl.${tmachine_libname}")
- set(LIBOMPTARGET_TESTED_PLUGINS
- "${LIBOMPTARGET_TESTED_PLUGINS}" PARENT_SCOPE)
- set(LIBOMPTARGET_SYSTEM_TARGETS
- "${LIBOMPTARGET_SYSTEM_TARGETS} ${tmachine_triple} ${tmachine_triple}-LTO" PARENT_SCOPE)
+ LINK_LIBS
+ PRIVATE
+ PluginCommon
+ ${OPENMP_PTHREAD_LIB}
+
+ NO_INSTALL_RPATH
+ )
- else(LIBOMPTARGET_DEP_LIBFFI_FOUND)
- libomptarget_say("Not building ${tmachine_name} NextGen offloading plugin: libffi dependency not found.")
- endif(LIBOMPTARGET_DEP_LIBFFI_FOUND)
+ if(LIBOMPTARGET_DEP_LIBFFI_FOUND)
+ libomptarget_say("Building ${tmachine_libname} plugin linked with libffi")
+ target_link_libraries("omptarget.rtl.${tmachine_libname}" PRIVATE
+ ${FFI_LIBRARIES})
+ target_include_directories("omptarget.rtl.${tmachine_libname}" PRIVATE
+ ${FFI_INCLUDE_DIRS})
+ else()
+ libomptarget_say("Building ${tmachine_libname} plugie for dlopened libffi")
+ target_sources("omptarget.rtl.${tmachine_libname}" PRIVATE
+ ${CMAKE_CURRENT_SOURCE_DIR}/../generic-elf-64bit/dynamic_ffi/ffi.cpp)
+ target_include_directories("omptarget.rtl.${tmachine_libname}" PRIVATE
+ ${CMAKE_CURRENT_SOURCE_DIR}/../generic-elf-64bit/dynamic_ffi)
+ endif()
+
+ if(OMPT_TARGET_DEFAULT AND LIBOMPTARGET_OMPT_SUPPORT)
+ target_link_libraries("omptarget.rtl.${tmachine_libname}" PRIVATE OMPT)
+ endif()
+
+ if(LIBOMP_HAVE_VERSION_SCRIPT_FLAG)
+ target_link_libraries("omptarget.rtl.${tmachine_libname}" PRIVATE
+ "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/../exports")
+ endif()
+
+ # Install plugin under the lib destination folder.
+ install(TARGETS "omptarget.rtl.${tmachine_libname}"
+ LIBRARY DESTINATION "${OPENMP_INSTALL_LIBDIR}")
+ set_target_properties("omptarget.rtl.${tmachine_libname}" PROPERTIES
+ INSTALL_RPATH "$ORIGIN" BUILD_RPATH "$ORIGIN:${CMAKE_CURRENT_BINARY_DIR}/.."
+ POSITION_INDEPENDENT_CODE ON
+ CXX_VISIBILITY_PRESET protected)
+
+ target_include_directories("omptarget.rtl.${tmachine_libname}" PRIVATE
+ ${LIBOMPTARGET_INCLUDE_DIR})
+
+ list(APPEND LIBOMPTARGET_TESTED_PLUGINS "omptarget.rtl.${tmachine_libname}")
+ set(LIBOMPTARGET_TESTED_PLUGINS
+ "${LIBOMPTARGET_TESTED_PLUGINS}" PARENT_SCOPE)
+ set(LIBOMPTARGET_SYSTEM_TARGETS
+ "${LIBOMPTARGET_SYSTEM_TARGETS} ${tmachine_triple} ${tmachine_triple}-LTO" PARENT_SCOPE)
else()
libomptarget_say("Not building ${tmachine_name} NextGen offloading plugin: machine not found in the system.")
endif()
diff --git a/openmp/libomptarget/plugins-nextgen/generic-elf-64bit/dynamic_ffi/ffi.cpp b/openmp/libomptarget/plugins-nextgen/generic-elf-64bit/dynamic_ffi/ffi.cpp
new file mode 100644
index 00000000000000..c79daa79858171
--- /dev/null
+++ b/openmp/libomptarget/plugins-nextgen/generic-elf-64bit/dynamic_ffi/ffi.cpp
@@ -0,0 +1,65 @@
+//===--- generic-elf-64bit/dynamic_ffi/ffi.cpp -------------------- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Implement subset of the FFI api by calling into the FFI library via dlopen
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/DynamicLibrary.h"
+#include <memory>
+
+#include "DLWrap.h"
+#include "ffi.h"
+
+DLWRAP_INITIALIZE()
+
+DLWRAP(ffi_call, 4);
+DLWRAP(ffi_prep_cif, 5);
+
+DLWRAP_FINALIZE()
+
+ffi_type ffi_type_void;
+ffi_type ffi_type_pointer;
+
+// Name of the FFI shared library.
+constexpr const char *FFI_PATH = "libffi.so";
+
+#define DYNAMIC_FFI_SUCCESS 0
+#define DYNAMIC_FFI_FAIL 1
+
+// Initializes the dynamic FFI wrapper.
+uint32_t ffi_init() {
+ std::string ErrMsg;
+ auto DynlibHandle = std::make_unique<llvm::sys::DynamicLibrary>(
+ llvm::sys::DynamicLibrary::getPermanentLibrary(FFI_PATH, &ErrMsg));
+ if (!DynlibHandle->isValid())
+ return DYNAMIC_FFI_FAIL;
+
+ for (size_t I = 0; I < dlwrap::size(); I++) {
+ const char *Sym = dlwrap::symbol(I);
+
+ void *P = DynlibHandle->getAddressOfSymbol(Sym);
+ if (P == nullptr)
+ return DYNAMIC_FFI_FAIL;
+
+ *dlwrap::pointer(I) = P;
+ }
+
+#define DYNAMIC_INIT(SYMBOL) \
+ { \
+ void *SymbolPtr = DynlibHandle->getAddressOfSymbol(#SYMBOL); \
+ if (!SymbolPtr) \
+ return DYNAMIC_FFI_FAIL; \
+ SYMBOL = *reinterpret_cast<decltype(SYMBOL) *>(SymbolPtr); \
+ }
+ DYNAMIC_INIT(ffi_type_void);
+ DYNAMIC_INIT(ffi_type_pointer);
+#undef DYNAMIC_INIT
+
+ return DYNAMIC_FFI_SUCCESS;
+}
diff --git a/openmp/libomptarget/plugins-nextgen/generic-elf-64bit/dynamic_ffi/ffi.h b/openmp/libomptarget/plugins-nextgen/generic-elf-64bit/dynamic_ffi/ffi.h
new file mode 100644
index 00000000000000..0ae025805e1d40
--- /dev/null
+++ b/openmp/libomptarget/plugins-nextgen/generic-elf-64bit/dynamic_ffi/ffi.h
@@ -0,0 +1,78 @@
+//===--- generic-elf-64bit/dynamic_ffi/ffi.cpp -------------------- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Provides a mirror to the parts of the FFI interface that the plugins require.
+//
+// libffi
+// - Copyright (c) 2011, 2014, 2019, 2021, 2022 Anthony Green
+// - Copyright (c) 1996-2003, 2007, 2008 Red Hat, Inc.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef DYNAMIC_FFI_FFI_H
+#define DYNAMIC_FFI_FFI_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+#define USES_DYNAMIC_FFI
+
+uint32_t ffi_init();
+
+typedef struct _ffi_type {
+ size_t size;
+ unsigned short alignment;
+ unsigned short type;
+ struct _ffi_type **elements;
+} ffi_type;
+
+typedef enum {
+ FFI_OK = 0,
+ FFI_BAD_TYPEDEF,
+ FFI_BAD_ABI,
+ FFI_BAD_ARGTYPE
+} ffi_status;
+
+// These are target depenent so we set them manually for each ABI by referencing
+// the FFI source.
+typedef enum ffi_abi {
+#if (defined(_M_X64) || defined(__x86_64__))
+ FFI_DEFAULT_ABI = 2, // FFI_UNIX64.
+#elif defined(__aarch64__) || defined(__arm64__) || defined(_M_ARM64)
+ FFI_DEFAULT_ABI = 1, // FFI_SYSV.
+#elif defined(__powerpc64__)
+ FFI_DEFAULT_ABI = 8, // FFI_LINUX.
+#elif defined(__s390x__)
+ FFI_DEFAULT_ABI = 1, // FFI_SYSV.
+#else
+#error "Unknown ABI"
+#endif
+} ffi_cif;
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define FFI_EXTERN extern
+#define FFI_API
+
+FFI_EXTERN ffi_type ffi_type_void;
+FFI_EXTERN ffi_type ffi_type_pointer;
+
+FFI_API
+void ffi_call(ffi_cif *cif, void (*fn)(void), void *rvalue, void **avalue);
+
+FFI_API
+ffi_status ffi_prep_cif(ffi_cif *cif, ffi_abi abi, unsigned int nargs,
+ ffi_type *rtype, ffi_type **atypes);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // DYNAMIC_FFI_FFI_H
diff --git a/openmp/libomptarget/plugins-nextgen/generic-elf-64bit/src/rtl.cpp b/openmp/libomptarget/plugins-nextgen/generic-elf-64bit/src/rtl.cpp
index 43569f25055594..7f66b6827bce00 100644
--- a/openmp/libomptarget/plugins-nextgen/generic-elf-64bit/src/rtl.cpp
+++ b/openmp/libomptarget/plugins-nextgen/generic-elf-64bit/src/rtl.cpp
@@ -383,6 +383,11 @@ struct GenELF64PluginTy final : public GenericPluginTy {
ompt::connectLibrary();
#endif
+#ifdef USES_DYNAMIC_FFI
+ if (auto Err = Plugin::check(ffi_init(), "Failed to initialize libffi"))
+ return std::move(Err);
+#endif
+
return NUM_DEVICES;
}
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