[Support] On Unix, let the CrashRecoveryContext return the signal code

Before this patch, the CrashRecoveryContext was returning -2 upon a signal, like ExecuteAndWait does. This didn't match the behavior on Windows, where the the exception code was returned.

We now return the signal's code, which optionally allows for re-throwing the signal later. Doing so requires all custom handlers to be removed first, through llvm::sys::unregisterHandlers() which we made a public API.

This is part of https://reviews.llvm.org/D70378

1 files changed, 4 insertions, 3 deletions

diff --git a/llvm/lib/Support/CrashRecoveryContext.cpp b/llvm/lib/Support/CrashRecoveryContext.cpp
index 2a41754..7609f04 100644
--- a/llvm/lib/Support/CrashRecoveryContext.cpp
+++ b/llvm/lib/Support/CrashRecoveryContext.cpp
@@ -375,9 +375,10 @@ static void CrashRecoverySignalHandler(int Signal) {
   sigaddset(&SigMask, Signal);
   sigprocmask(SIG_UNBLOCK, &SigMask, nullptr);
 
-  // As per convention, -2 indicates a crash or timeout as opposed to failure to
-  // execute (see llvm/include/llvm/Support/Program.h)
-  int RetCode = -2;
+  // Return the same error code as if the program crashed, as mentioned in the
+  // section "Exit Status for Commands":
+  // https://pubs.opengroup.org/onlinepubs/9699919799/xrat/V4_xcu_chap02.html
+  int RetCode = 128 + Signal;
 
   // Don't consider a broken pipe as a crash (see clang/lib/Driver/Driver.cpp)
   if (Signal == SIGPIPE)