[DLCov] Origin-Tracking: Enable collecting and symbolizing stack traces (#143591)

This patch is part of a series that adds origin-tracking to the debugify
source location coverage checks, allowing us to report symbolized stack
traces of the point where missing source locations appear.

This patch adds a pair of new functions in `signals.h` that can be used
to collect and symbolize stack traces respectively. This has major
implementation overlap with the existing stack trace
collection/symbolizing methods, but the existing functions are
specialized for dumping a stack trace to stderr when LLVM crashes, while
these new functions are meant to be called repeatedly during the
execution of the program, and therefore we need a separate set of
functions.

1 files changed, 15 insertions, 0 deletions

diff --git a/llvm/lib/Support/Unix/Signals.inc b/llvm/lib/Support/Unix/Signals.inc
index 6668a29..a4525a5 100644
--- a/llvm/lib/Support/Unix/Signals.inc
+++ b/llvm/lib/Support/Unix/Signals.inc
@@ -507,6 +507,21 @@ static int dl_iterate_phdr_cb(dl_phdr_info *info, size_t size, void *arg) {
   return 0;
 }
 
+#if LLVM_ENABLE_DEBUGLOC_TRACKING_ORIGIN
+#if !defined(HAVE_BACKTRACE)
+#error DebugLoc origin-tracking currently requires `backtrace()`.
+#endif
+namespace llvm {
+namespace sys {
+template <unsigned long MaxDepth>
+int getStackTrace(std::array<void *, MaxDepth> &StackTrace) {
+  return backtrace(StackTrace.data(), MaxDepth);
+}
+template int getStackTrace<16ul>(std::array<void *, 16ul> &);
+} // namespace sys
+} // namespace llvm
+#endif
+
 /// If this is an ELF platform, we can find all loaded modules and their virtual
 /// addresses with dl_iterate_phdr.
 static bool findModulesAndOffsets(void **StackTrace, int Depth,