[llvm-dev] llvm 5.0 release rc1 : ExecutionEngine fatal error on MCJIT::getFunctionAddress

Daniel Neilson via llvm-dev
Thu, 27 Jul 2017 14:06:03 -0000

Relevant change:

commit a81793582b3c47869680d354a97d59c55779c349
Author: Lang Hames <lhames at gmail.com<mailto:lhames at gmail.com>>
Date:   Fri Jul 7 02:59:13 2017 +0000

    [ORC] Errorize the ORC APIs.

    This patch updates the ORC layers and utilities to return and propagate
    llvm::Errors where appropriate. This is necessary to allow ORC to safely
handle
    error cases in cross-process and remote JITing.



    git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk at 307350
91177308-0d34-0410-b5e6-96231b3b80d8




On Jul 27, 2017, at 8:38 AM, Christophe Duvernois via llvm-dev <llvm-dev at
lists.llvm.org<mailto:llvm-dev at lists.llvm.org>> wrote:

Hi everyone,

In llvm 4.0 the MCJIT::getFunctionAddress function return 0 (a null address)
when the symbol is not found :

uint64_t MCJIT::getSymbolAddress(const std::string &Name, bool
CheckFunctionsOnly) {
  std::string MangledName;
  {
    raw_string_ostream MangledNameStream(MangledName);
    Mangler::getNameWithPrefix(MangledNameStream, Name, getDataLayout());
  }
  return findSymbol(MangledName, CheckFunctionsOnly).getAddress();
}

Now with the current implementation (llvm 5.0 rc1 tag) :

uint64_t MCJIT::getSymbolAddress(const std::string &Name, bool
CheckFunctionsOnly) {
  std::string MangledName;
  {
    raw_string_ostream MangledNameStream(MangledName);
    Mangler::getNameWithPrefix(MangledNameStream, Name, getDataLayout());
  }
  if (auto Sym = findSymbol(MangledName, CheckFunctionsOnly)) {
    if (auto AddrOrErr = Sym.getAddress())
      return *AddrOrErr;
    else {
      report_fatal_error(AddrOrErr.takeError());
    }
  } else {
    report_fatal_error(Sym.takeError());
  }
}

If the function findSymbol return nullptr, we are executing report_fatal_error
and kill everything :(

What is the reason for this change? Is this a bug?

If this is intended, how can we check from the ExecutionEngine that the symbol
already exists?


Regards,
Christophe





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