[ORC] Add a runAsMain utility function to ExecutionUtils.

The runAsMain function takes a pointer to a function with a standard C main
signature, int(*)(int, char*[]), and invokes it using the given arguments and
program name. The arguments are copied into writable temporary storage as
required by the C and C++ specifications, so runAsMain safe to use when calling
main functions that modify their arguments in-place.

This patch also uses the new runAsMain function to replace hand-rolled versions
in lli, llvm-jitlink, and the SpeculativeJIT example.

1 files changed, 3 insertions, 20 deletions

diff --git a/llvm/tools/llvm-jitlink/llvm-jitlink.cpp b/llvm/tools/llvm-jitlink/llvm-jitlink.cpp
index 003a333d956..0e0953d37b6 100644
--- a/llvm/tools/llvm-jitlink/llvm-jitlink.cpp
+++ b/llvm/tools/llvm-jitlink/llvm-jitlink.cpp
@@ -769,25 +769,6 @@ static Expected<JITEvaluatedSymbol> getMainEntryPoint(Session &S) {
   return S.ES.lookup(S.JDSearchOrder, EntryPointName);
 }
 
-Expected<int> runEntryPoint(Session &S, JITEvaluatedSymbol EntryPoint) {
-  assert(EntryPoint.getAddress() && "Entry point address should not be null");
-
-  constexpr const char *JITProgramName = "<llvm-jitlink jit'd code>";
-  auto PNStorage = std::make_unique<char[]>(strlen(JITProgramName) + 1);
-  strcpy(PNStorage.get(), JITProgramName);
-
-  std::vector<const char *> EntryPointArgs;
-  EntryPointArgs.push_back(PNStorage.get());
-  for (auto &InputArg : InputArgv)
-    EntryPointArgs.push_back(InputArg.data());
-  EntryPointArgs.push_back(nullptr);
-
-  using MainTy = int (*)(int, const char *[]);
-  MainTy EntryPointPtr = reinterpret_cast<MainTy>(EntryPoint.getAddress());
-
-  return EntryPointPtr(EntryPointArgs.size() - 1, EntryPointArgs.data());
-}
-
 struct JITLinkTimers {
   TimerGroup JITLinkTG{"llvm-jitlink timers", "timers for llvm-jitlink phases"};
   Timer LoadObjectsTimer{"load", "time to load/add object files", JITLinkTG};
@@ -841,8 +822,10 @@ int main(int argc, char *argv[]) {
 
   int Result = 0;
   {
+    using MainTy = int (*)(int, char *[]);
+    auto EntryFn = jitTargetAddressToFunction<MainTy>(EntryPoint.getAddress());
     TimeRegion TR(Timers ? &Timers->RunTimer : nullptr);
-    Result = ExitOnErr(runEntryPoint(S, EntryPoint));
+    Result = runAsMain(EntryFn, InputArgv, StringRef(InputFiles.front()));
   }
 
   return Result;