[Clang][Driver] After default -fintegrated-cc1, make llvm::report_fatal_error() generate preprocessed source + reproducer.sh again.

Added a test for #pragma clang __debug llvm_fatal_error to test for the original issue.
Added llvm::sys::Process::Exit() and replaced ::exit() in places where it was appropriate. This new function would call the current CrashRecoveryContext if one is running on the same thread; or call ::exit() otherwise.

Fixes PR44705.

Differential Revision: https://reviews.llvm.org/D73742

(cherry picked from commit faace365088a2a3a4cb1050a9facfc34a7a56577)

2 files changed, 11 insertions, 0 deletions

diff --git a/llvm/include/llvm/Support/CrashRecoveryContext.h b/llvm/include/llvm/Support/CrashRecoveryContext.h
index beeb855c7c5..61a1bd405a4 100644
--- a/llvm/include/llvm/Support/CrashRecoveryContext.h
+++ b/llvm/include/llvm/Support/CrashRecoveryContext.h
@@ -97,6 +97,11 @@ public:
     return RunSafelyOnThread([&]() { Fn(UserData); }, RequestedStackSize);
   }
 
+  /// Explicitly trigger a crash recovery in the current process, and
+  /// return failure from RunSafely(). This function does not return.
+  LLVM_ATTRIBUTE_NORETURN
+  void HandleExit(int RetCode);
+
   /// In case of a crash, this is the crash identifier.
   int RetCode = 0;
 
diff --git a/llvm/include/llvm/Support/Process.h b/llvm/include/llvm/Support/Process.h
index 67e37912519..e934b7413c1 100644
--- a/llvm/include/llvm/Support/Process.h
+++ b/llvm/include/llvm/Support/Process.h
@@ -201,6 +201,12 @@ public:
   /// Get the result of a process wide random number generator. The
   /// generator will be automatically seeded in non-deterministic fashion.
   static unsigned GetRandomNumber();
+
+  /// Equivalent to ::exit(), except when running inside a CrashRecoveryContext.
+  /// In that case, the control flow will resume after RunSafely(), like for a
+  /// crash, rather than exiting the current process.
+  LLVM_ATTRIBUTE_NORETURN
+  static void Exit(int RetCode);
 };
 
 }