Replace exit() calls with exceptions in shared library code

In lib/Support/ErrorHandling.cpp, remove the #ifndef LLVM_ON_WIN32 guard
so that report_fatal_error() and llvm_unreachable_internal() throw
hlsl::Exception on all platforms instead of calling exit(1)/abort() on
non-Windows.

In lib/Support/CommandLine.cpp, replace exit() calls with
report_fatal_error() which now throws an exception on all platforms.

Co-authored-by: damyanp <[email protected]>

Author: Copilot

lib/Support/CommandLine.cpp

@@ -1111,7 +1111,7 @@ void CommandLineParser::ParseCommandLineOptions(int argc,
 
   // If we had an error processing our arguments, don't let the program execute
   if (ErrorParsing)
-    exit(1);
+    report_fatal_error("Error in command-line option processing"); // HLSL Change - don't exit() in shared library
 }
 
 //===----------------------------------------------------------------------===//
@@ -1547,7 +1547,7 @@ class HelpPrinter {
     GlobalParser->MoreHelp.clear();
 
     // Halt the program since help information was printed
-    exit(0);
+    report_fatal_error("Help information was printed"); // HLSL Change - don't exit() in shared library
   }
 };
 
@@ -1798,7 +1798,7 @@ class VersionPrinter {
 
     if (OverrideVersionPrinter != nullptr) {
       (*OverrideVersionPrinter)();
-      exit(0);
+      report_fatal_error("Version information was printed"); // HLSL Change - don't exit() in shared library
     }
     print();
 
@@ -1812,7 +1812,7 @@ class VersionPrinter {
         (*I)();
     }
 
-    exit(0);
+    report_fatal_error("Version information was printed"); // HLSL Change - don't exit() in shared library
   }
 };
 } // End anonymous namespace

lib/Support/ErrorHandling.cpp

@@ -88,34 +88,12 @@ void llvm::report_fatal_error(const Twine &Reason, bool GenCrashDiag) {
     handlerData = ErrorHandlerUserData;
   }
 
-#ifndef LLVM_ON_WIN32 // HLSL Change - unwind if necessary, but don't terminate the process
-  if (handler) {
-    handler(handlerData, Reason.str(), GenCrashDiag);
-  } else {
-    // Blast the result out to stderr.  We don't try hard to make sure this
-    // succeeds (e.g. handling EINTR) and we can't use errs() here because
-    // raw ostreams can call report_fatal_error.
-    SmallVector<char, 64> Buffer;
-    raw_svector_ostream OS(Buffer);
-    OS << "LLVM ERROR: " << Reason << "\n";
-    StringRef MessageStr = OS.str();
-    ssize_t written = ::write(2, MessageStr.data(), MessageStr.size());
-    (void)written; // If something went wrong, we deliberately just give up.
-  }
-
-  // If we reached here, we are failing ungracefully. Run the interrupt handlers
-  // to make sure any special cleanups get done, in particular that we remove
-  // files registered with RemoveFileOnSignal.
-  sys::RunInterruptHandlers();
-
-  exit(1);
-#else
+  // HLSL Change - unwind if necessary, but don't terminate the process
   if (handler) {
     handler(handlerData, Reason.str(), GenCrashDiag);
   }
 
   throw hlsl::Exception(DXC_E_LLVM_FATAL_ERROR, std::string("LLVM ERROR: ") + Reason.str() + "\n");
-#endif
 }
 
 void llvm::llvm_unreachable_internal(const char *msg, const char *file,
@@ -132,12 +110,8 @@ void llvm::llvm_unreachable_internal(const char *msg, const char *file,
   if (file)
     OS << " at " << file << ":" << line;
   OS << "!\n";
-#ifndef LLVM_ON_WIN32 // HLSL Change - unwind if necessary, but don't terminate the process
-  dbgs() << OS.str();
-  abort();
-#else
+  // HLSL Change - unwind if necessary, but don't terminate the process
   throw hlsl::Exception(DXC_E_LLVM_UNREACHABLE, OS.str());
-#endif
 }
 
 void llvm::llvm_cast_assert_internal(const char *func) {