[BOLT] Add function-splitting test

Author: bgergely0

bolt/test/runtime/AArch64/pacret-function-split.cpp

@@ -0,0 +1,42 @@
+/* This test check that the negate-ra-state CFIs are properly emitted in case of
+   function splitting. The test checks two things:
+    - we split at the correct location: to test the feature,
+        we need to split *before* the bl __cxa_throw@PLT call is made,
+        so the unwinder has to unwind from the split (cold) part.
+
+    - the BOLTed binary runs, and returns the string from foo.
+
+# REQUIRES: system-linux,bolt-runtime
+
+# FDATA: 1 main #split# 1 _Z3foov 0 0 1
+
+# RUN: %clangxx --target=aarch64-unknown-linux-gnu \
+# RUN: -mbranch-protection=pac-ret %s -o %t.exe -Wl,-q
+# RUN: link_fdata %s %t.exe %t.fdata
+# RUN: llvm-bolt %t.exe -o %t.bolt --split-functions --split-eh \
+# RUN: --split-strategy=profile2 --split-all-cold --print-split \
+# RUN: --print-only=_Z3foov --data=%t.fdata 2>&1 | FileCheck \
+# RUN: --check-prefix=BOLT-CHECK %s
+# RUN: %t.bolt | FileCheck %s  --check-prefix=RUN-CHECK
+
+# BOLT-CHECK-NOT: bl      __cxa_throw@PLT
+# BOLT-CHECK: -------   HOT-COLD SPLIT POINT   -------
+# BOLT-CHECK: bl      __cxa_throw@PLT
+
+# RUN-CHECK: Exception caught: Exception from foo().
+*/
+
+#include <cstdio>
+#include <stdexcept>
+
+void foo() { throw std::runtime_error("Exception from foo()."); }
+
+int main() {
+  try {
+    __asm__ __volatile__("split:");
+    foo();
+  } catch (const std::exception &e) {
+    printf("Exception caught: %s\n", e.what());
+  }
+  return 0;
+}