[AMDGPU] Adding mutex to guard lld::elf::link interface use

[jerryyin]

Summary

check-mlir target run tests simultaneously with multiple threads. This caused multiple threads to invoke the lld::elf::link() interface at the same time. Since the interface does not have a thread-safe implementation, add a metex to prevent multi-threaded access.

I discovered this by looking the the failure stack trace. lld/ELF/symbolTable.cpp, SymbolTable::insert() hit into an assert with related to Epoch Trackers. The root cause is to due to there is no protection around the symMap (update) who is implemented by denseMap and is not thread safe.

mlir/tools/mlir-rocm-runner/mlir-rocm-runner.cpp

 #include "llvm/MC/MCTargetOptionsCommandFlags.h"
 
 // lld headers.
 #include "lld/Common/Driver.h"
 
 // HIP headers.
 #include "hip/hip_version.h"
 
+#include <mutex>
+
 using namespace mlir;
 using namespace llvm;
 
 using Blob = SmallVector<char, 0>;
 
 static cl::opt<std::string> tripleName("triple", cl::desc("target triple"),
                                        cl::value_desc("triple string"),
                                        cl::init("amdgcn-amd-amdhsa"));
static LogicalResult assembleIsa(const std::string isa, StringRef name,
   }
 
   parser->setTargetParser(*tap);
   parser->Run(false);
 
   return success();
 }
 
+static std::mutex mutex;
 static LogicalResult createHsaco(const Blob &isaBlob, StringRef name,
                                  Blob &hsacoBlob) {
   // Save the ISA binary to a temp file.
   int tempIsaBinaryFd = -1;
   SmallString<128> tempIsaBinaryFilename;
   std::error_code ec = sys::fs::createTemporaryFile(
       "kernel", "o", tempIsaBinaryFd, tempIsaBinaryFilename);
   if (ec) {
ec = sys::fs::createTemporaryFile("kernel", "hsaco", tempHsacoFD,
                                     tempHsacoFilename);
   if (ec) {
     WithColor::error(errs(), name)
         << "temporary file for HSA code object creation error.\n";
     return failure();
   }
   FileRemover cleanupHsaco(tempHsacoFilename);
 
+  const std::lock_guard<std::mutex> lock(mutex);
   // Invoke lld. Expect a true return value from lld.
   bool ret = lld::elf::link({"ld.lld", "-shared", tempIsaBinaryFilename.c_str(),
                              "-o", tempHsacoFilename.c_str()},
                             /*canEarlyExit=*/false, llvm::outs(), llvm::errs());
   if (!ret) {
     WithColor::error(errs(), name) << "lld invocation error.\n";
     return failure();
   }