[llvm] [Offload] Add support for riscv64 to host plugin (PR #115773)

[via llvm-commits]

https://github.com/aurel32 created https://github.com/llvm/llvm-project/pull/115773

This adds support for the riscv64 architecture to the offload host plugin. The check to define FFI_DEFAULT_ABI is intentionally not guarded by __riscv_xlen as the value is the same for riscv32 and riscv64 (support for OpenMP on riscv32 is still under review).

>From 297847938d56291d0f63e93ba5cde848d3aa45d6 Mon Sep 17 00:00:00 2001
From: Aurelien Jarno <aurelien at aurel32.net>
Date: Mon, 11 Nov 2024 11:12:54 +0100
Subject: [PATCH] [Offload] Add support for riscv64 to host plugin

This adds support for the riscv64 architecture to the offload host
plugin. The check to define FFI_DEFAULT_ABI is intentionally not guarded
by __riscv_xlen as the value is the same for riscv32 and riscv64
(support for OpenMP on riscv32 is still under review).
---
 offload/CMakeLists.txt                           | 2 ++
 offload/plugins-nextgen/common/src/Utils/ELF.cpp | 2 ++
 offload/plugins-nextgen/host/CMakeLists.txt      | 6 +++++-
 offload/plugins-nextgen/host/dynamic_ffi/ffi.h   | 3 ++-
 offload/plugins-nextgen/host/src/rtl.cpp         | 2 ++
 5 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/offload/CMakeLists.txt b/offload/CMakeLists.txt
index 9b771d1116ee38..dfd25bad608436 100644
--- a/offload/CMakeLists.txt
+++ b/offload/CMakeLists.txt
@@ -199,6 +199,8 @@ set (LIBOMPTARGET_ALL_TARGETS "${LIBOMPTARGET_ALL_TARGETS} nvptx64-nvidia-cuda-L
 set (LIBOMPTARGET_ALL_TARGETS "${LIBOMPTARGET_ALL_TARGETS} nvptx64-nvidia-cuda-JIT-LTO")
 set (LIBOMPTARGET_ALL_TARGETS "${LIBOMPTARGET_ALL_TARGETS} s390x-ibm-linux-gnu")
 set (LIBOMPTARGET_ALL_TARGETS "${LIBOMPTARGET_ALL_TARGETS} s390x-ibm-linux-gnu-LTO")
+set (LIBOMPTARGET_ALL_TARGETS "${LIBOMPTARGET_ALL_TARGETS} riscv64-unknown-linux-gnu")
+set (LIBOMPTARGET_ALL_TARGETS "${LIBOMPTARGET_ALL_TARGETS} riscv64-unknown-linux-gnu-LTO")
 
 # Once the plugins for the different targets are validated, they will be added to
 # the list of supported targets in the current system.
diff --git a/offload/plugins-nextgen/common/src/Utils/ELF.cpp b/offload/plugins-nextgen/common/src/Utils/ELF.cpp
index 90d6950b83e5ad..88642fd5b56400 100644
--- a/offload/plugins-nextgen/common/src/Utils/ELF.cpp
+++ b/offload/plugins-nextgen/common/src/Utils/ELF.cpp
@@ -45,6 +45,8 @@ uint16_t utils::elf::getTargetMachine() {
   return EM_AARCH64;
 #elif defined(__powerpc64__)
   return EM_PPC64;
+#elif defined(__riscv)
+  return EM_RISCV;
 #else
 #warning "Unknown ELF compilation target architecture"
   return EM_NONE;
diff --git a/offload/plugins-nextgen/host/CMakeLists.txt b/offload/plugins-nextgen/host/CMakeLists.txt
index 0ab827a355379d..cbfe4b951af453 100644
--- a/offload/plugins-nextgen/host/CMakeLists.txt
+++ b/offload/plugins-nextgen/host/CMakeLists.txt
@@ -1,4 +1,4 @@
-set(supported_targets x86_64 aarch64 ppc64 ppc64le s390x)
+set(supported_targets x86_64 aarch64 ppc64 ppc64le riscv64 s390x)
 if(NOT ${CMAKE_SYSTEM_PROCESSOR} IN_LIST supported_targets)
   message(STATUS "Not building ${machine} NextGen offloading plugin")
   return()
@@ -59,4 +59,8 @@ elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "s390x$")
   list(APPEND LIBOMPTARGET_SYSTEM_TARGETS
        "s390x-ibm-linux-gnu" "s390x-ibm-linux-gnu-LTO")
   set(LIBOMPTARGET_SYSTEM_TARGETS "${LIBOMPTARGET_SYSTEM_TARGETS}" PARENT_SCOPE)
+elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "riscv64$")
+  list(APPEND LIBOMPTARGET_SYSTEM_TARGETS
+       "riscv64-unknown-linux-gnu" "riscv64-unknown-linux-gnu-LTO")
+  set(LIBOMPTARGET_SYSTEM_TARGETS "${LIBOMPTARGET_SYSTEM_TARGETS}" PARENT_SCOPE)
 endif()
diff --git a/offload/plugins-nextgen/host/dynamic_ffi/ffi.h b/offload/plugins-nextgen/host/dynamic_ffi/ffi.h
index 0ae025805e1d40..8b4e0286d65e3c 100644
--- a/offload/plugins-nextgen/host/dynamic_ffi/ffi.h
+++ b/offload/plugins-nextgen/host/dynamic_ffi/ffi.h
@@ -43,7 +43,8 @@ typedef enum {
 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)
+#elif defined(__aarch64__) || defined(__arm64__) || defined(_M_ARM64) ||       \
+    defined(__riscv)
   FFI_DEFAULT_ABI = 1, // FFI_SYSV.
 #elif defined(__powerpc64__)
   FFI_DEFAULT_ABI = 8, // FFI_LINUX.
diff --git a/offload/plugins-nextgen/host/src/rtl.cpp b/offload/plugins-nextgen/host/src/rtl.cpp
index fe296b77c7d557..2395cea6a7de75 100644
--- a/offload/plugins-nextgen/host/src/rtl.cpp
+++ b/offload/plugins-nextgen/host/src/rtl.cpp
@@ -440,6 +440,8 @@ struct GenELF64PluginTy final : public GenericPluginTy {
 #else
     return llvm::Triple::ppc64;
 #endif
+#elif defined(__riscv) && (__riscv_xlen == 64)
+    return llvm::Triple::ArchType::riscv64;
 #else
     return llvm::Triple::UnknownArch;
 #endif