[JITLink] Add platform and runtime support for Linux riscv64

[StephenFan]

Summary

This patch add platform and runtime support for Linux riscv64 platform. As show in test cases, atexit, __cxa_atexit, static initializer were supported.

These test cases were passed in my local machine. But it seems that LLVM buildbot doesn't have a riscv64 worker to test this test cases.

[lhames]

Very belatedly -- LGTM! Thanks @StephenFan!

compiler-rt/cmake/Modules/AllSupportedArchDefs.cmake

 set(ALL_XRAY_SUPPORTED_ARCH ${X86_64})
 else()
 set(ALL_XRAY_SUPPORTED_ARCH ${X86_64} ${ARM32} ${ARM64} ${MIPS32} ${MIPS64}
     powerpc64le ${HEXAGON})
 endif()
 set(ALL_SHADOWCALLSTACK_SUPPORTED_ARCH ${ARM64})
 
 if (UNIX)
-set(ALL_ORC_SUPPORTED_ARCH ${X86_64} ${ARM64} ${ARM32})
+set(ALL_ORC_SUPPORTED_ARCH ${X86_64} ${ARM64} ${ARM32} ${RISCV64})
 endif()

compiler-rt/test/orc/TestCases/Linux/riscv64/lit.local.cfg.py

+if config.root.host_arch != 'riscv64':
+    config.unsupported = True
+
+if config.target_arch != 'riscv64':
+    config.unsupported = True

compiler-rt/test/orc/TestCases/Linux/riscv64/trivial-atexit.S

+// Test that the runtime correctly interposes atexit.                                                                           
+//                                                                                                                              
+// RUN: %clang -c -o %t %s                                                                                                      
+// RUN: %llvm_jitlink %t
+
+  .file "atexit.c"
+  .option pic
+  .option norelax
+  .text
+  .align  1
+// OnExit destructor resets the test result override to zero.
+  .globl  onExit
+  .type onExit, @function
+onExit:
+  li  a0,0
+  tail  llvm_jitlink_setTestResultOverride@plt
+  .size onExit, .-onExit
+  .section  .text.startup,"ax",@progbits
+  .align  1
+ // main registers the atexit and sets the test result to one.
+  .globl  main
+  .type main, @function
+main:
+  addi  sp,sp,-16
+  la  a0,onExit
+  sd  ra,8(sp)
+  call  atexit@plt
+  li  a0,1
+  call  llvm_jitlink_setTestResultOverride@plt
+  ld  ra,8(sp)
+  li  a0,0
+  addi  sp,sp,16
+  jr  ra
+  .size main, .-main
+  .section  .note.GNU-stack,"",@progbits

compiler-rt/test/orc/TestCases/Linux/riscv64/trivial-cxa-atexit.S

+// Test that the runtime correctly interposes ___cxa_atexit.
+//
+// RUN: %clang -c -o %t %s
+// RUN: %llvm_jitlink %t
+
+  .option pic
+  .text
+  .align  1
+  .globl  _Z6onExitv
+  .type _Z6onExitv, @function
+_Z6onExitv:
+  li  a0,0
+  tail  llvm_jitlink_setTestResultOverride@plt
+  .size _Z6onExitv, .-_Z6onExitv
+  .section  .text.startup,"ax",@progbits
+  .align  1
+  .globl  main
+  .type main, @function
+main:
+  addi  sp,sp,-16
+  la  a0,_Z6onExitv
+  la  a1,t
+  la  a2,__dso_handle
+  sd  ra,8(sp)
+  call  __cxa_atexit@plt
+  li  a0,1
+  call  llvm_jitlink_setTestResultOverride@plt
+  ld  ra,8(sp)
+  li  a0,0
+  addi  sp,sp,16
+  jr  ra
+  .size main, .-main
+  .globl  t
+  .section  .sbss,"aw",@nobits
+  .align  3
+  .type t, @object
+  .size t, 1
+t:
+  .zero 1
+  .hidden __dso_handle
+  .ident  "GCC: (GNU) 11.1.0"
+  .section  .note.GNU-stack,"",@progbits

compiler-rt/test/orc/TestCases/Linux/riscv64/trivial-static-initializer.S

+// Test that basic ELF static initializers work. The main function in this
+// test returns the value of 'x', which is initially 1 in the data section,
+// and reset to 0 if the _static_init function is run. If the static initializer
+// does not run then main will return 1, causing the test to be treated as a
+// failure.
+//
+// RUN: %clang -c -o %t %s
+// RUN: %llvm_jitlink %t
+//
+
+  .text
+  .globl main
+  .p2align 1
+main:
+  la a0, x
+  ret
+
+  .p2align 1
+static_init:
+  la a1, x
+  li a2, 0
+  sd a2, (a1)
+  ret
+
+  .data
+  .globl x
+  .p2align 2
+x:
+  .long 1
+  .size x, 4
+
+  .section .init_array,"aw",@init_array
+  .p2align 3
+  .quad static_init

llvm/lib/ExecutionEngine/Orc/ELFNixPlatform.cpp

 //===------ ELFNixPlatform.cpp - Utilities for executing MachO in Orc -----===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/ExecutionEngine/Orc/ELFNixPlatform.h"
 
 #include "llvm/BinaryFormat/ELF.h"
 #include "llvm/ExecutionEngine/JITLink/ELF_x86_64.h"
+#include "llvm/ExecutionEngine/JITLink/riscv.h"
 #include "llvm/ExecutionEngine/JITLink/x86_64.h"
 #include "llvm/ExecutionEngine/Orc/DebugUtils.h"
 #include "llvm/ExecutionEngine/Orc/ExecutionUtils.h"
 #include "llvm/Support/BinaryByteStream.h"
 #include "llvm/Support/Debug.h"
 
 #define DEBUG_TYPE "orc"
 
const auto &TT =
         ENP.getExecutionSession().getExecutorProcessControl().getTargetTriple();
 
     switch (TT.getArch()) {
     case Triple::x86_64:
       PointerSize = 8;
       Endianness = support::endianness::little;
       EdgeKind = jitlink::x86_64::Pointer64;
       break;
+    case Triple::riscv64:
+      PointerSize = 8;
+      Endianness = support::endianness::little;
+      EdgeKind = jitlink::riscv::R_RISCV_64;
+      break;
     default:
       llvm_unreachable("Unrecognized architecture");
     }
 
     // void *__dso_handle = &__dso_handle;
     auto G = std::make_unique<jitlink::LinkGraph>(
         "<DSOHandleMU>", TT, PointerSize, Endianness,
         jitlink::getGenericEdgeKindName);
if (Name.equals(SecName))
       return true;
   }
   return false;
 }
 
 bool ELFNixPlatform::supportedTarget(const Triple &TT) {
   switch (TT.getArch()) {
   case Triple::x86_64:
+  case Triple::riscv64:
     return true;
   default:
     return false;
   }
 }
 
 ELFNixPlatform::ELFNixPlatform(
     ExecutionSession &ES, ObjectLinkingLayer &ObjLinkingLayer,