[VE] Fix initializer visibility

[trofi]

Summary

Before the change attempt to link libLTO.so against shared
LLVM library failed as:

[ 76%] Linking CXX shared library ../../lib/libLTO.so
... /usr/bin/cmake -E cmake_link_script CMakeFiles/LTO.dir/link.txt --verbose=1
c++ -o ...libLTO.so.12git ...ibLLVM-12git.so
ld: CMakeFiles/LTO.dir/lto.cpp.o: in function `llvm::InitializeAllTargetInfos()':
include/llvm/Config/Targets.def:31: undefined reference to `LLVMInitializeVETargetInfo'

It happens because on linux llvm build system sets default
symbol visibility to "hidden". The fix is to set visibility
back to "default" for exported APIs with LLVM_EXTERNAL_VISIBILITY.

Bug: https://bugs.llvm.org/show_bug.cgi?id=47847
Signed-off-by: Sergei Trofimovich <[e-mail]>

[simoll]

Thanks!

llvm/lib/Target/VE/Disassembler/VEDisassembler.cpp

 //===- VEDisassembler.cpp - Disassembler for VE -----------------*- 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
 //
 //===----------------------------------------------------------------------===//
 //
 // This file is part of the VE Disassembler.
 //
 //===----------------------------------------------------------------------===//
 
 #include "MCTargetDesc/VEMCTargetDesc.h"
 #include "TargetInfo/VETargetInfo.h"
 #include "VE.h"
 #include "llvm/MC/MCAsmInfo.h"
 #include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCDisassembler/MCDisassembler.h"
 #include "llvm/MC/MCFixedLenDisassembler.h"
 #include "llvm/MC/MCInst.h"
 #include "llvm/Support/TargetRegistry.h"

 } // namespace
 
 static MCDisassembler *createVEDisassembler(const Target &T,
                                             const MCSubtargetInfo &STI,
                                             MCContext &Ctx) {
   return new VEDisassembler(STI, Ctx);
 }
 
-extern "C" void LLVMInitializeVEDisassembler() {
+extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeVEDisassembler() {
   // Register the disassembler.
   TargetRegistry::RegisterMCDisassembler(getTheVETarget(),
                                          createVEDisassembler);
 }
 
 static const unsigned I32RegDecoderTable[] = {
     VE::SW0,  VE::SW1,  VE::SW2,  VE::SW3,  VE::SW4,  VE::SW5,  VE::SW6,
     VE::SW7,  VE::SW8,  VE::SW9,  VE::SW10, VE::SW11, VE::SW12, VE::SW13,

llvm/lib/Target/VE/MCTargetDesc/VEMCTargetDesc.cpp

 static MCInstPrinter *createVEMCInstPrinter(const Triple &T,
                                             unsigned SyntaxVariant,
                                             const MCAsmInfo &MAI,
                                             const MCInstrInfo &MII,
                                             const MCRegisterInfo &MRI) {
   return new VEInstPrinter(MAI, MII, MRI);
 }
 
-extern "C" void LLVMInitializeVETargetMC() {
+extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeVETargetMC() {
   // Register the MC asm info.
   RegisterMCAsmInfoFn X(getTheVETarget(), createVEMCAsmInfo);
 
   for (Target *T : {&getTheVETarget()}) {
     // Register the MC instruction info.
     TargetRegistry::RegisterMCInstrInfo(*T, createVEMCInstrInfo);
 
     // Register the MC register info.

llvm/lib/Target/VE/TargetInfo/VETargetInfo.cpp

 //===-- VETargetInfo.cpp - VE Target Implementation -----------------------===//
 //
 // 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 "TargetInfo/VETargetInfo.h"
 #include "llvm/Support/TargetRegistry.h"
 
 using namespace llvm;
 
 Target &llvm::getTheVETarget() {
   static Target TheVETarget;
   return TheVETarget;
 }
 
-extern "C" void LLVMInitializeVETargetInfo() {
+extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeVETargetInfo() {
   RegisterTarget<Triple::ve, /*HasJIT=*/false> X(getTheVETarget(), "ve",
                                                  "VE", "VE");
 }

llvm/lib/Target/VE/VEAsmPrinter.cpp

void VEAsmPrinter::emitInstruction(const MachineInstr *MI) {
   do {
     MCInst TmpInst;
     LowerVEMachineInstrToMCInst(&*I, TmpInst, *this);
     EmitToStreamer(*OutStreamer, TmpInst);
   } while ((++I != E) && I->isInsideBundle()); // Delay slot check.
 }
 
 // Force static initialization.
-extern "C" void LLVMInitializeVEAsmPrinter() {
+extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeVEAsmPrinter() {
   RegisterAsmPrinter<VEAsmPrinter> X(getTheVETarget());
 }

llvm/lib/Target/VE/VETargetMachine.cpp

 #include "llvm/CodeGen/TargetPassConfig.h"
 #include "llvm/IR/LegacyPassManager.h"
 #include "llvm/Support/TargetRegistry.h"
 
 using namespace llvm;
 
 #define DEBUG_TYPE "ve"
 
-extern "C" void LLVMInitializeVETarget() {
+extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeVETarget() {
   // Register the target.
   RegisterTargetMachine<VETargetMachine> X(getTheVETarget());
 }
 
 static std::string computeDataLayout(const Triple &T) {
   // Aurora VE is little endian
   std::string Ret = "e";