Add a flag to dump the current stack trace when emitting a diagnostic.

It is often desirable to know where within the program that a diagnostic was emitted, without reverting to assert/unreachable which crash the program. This change adds a flag `mlir-print-stacktrace-on-diagnostic` that attaches the current stack trace as a note to every diagnostic that gets emitted.

PiperOrigin-RevId: 283996373

mlir/lib/IR/Diagnostics.cpp

@@ -25,15 +25,22 @@
 #include "llvm/ADT/MapVector.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringMap.h"
+#include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Mutex.h"
 #include "llvm/Support/PrettyStackTrace.h"
 #include "llvm/Support/Regex.h"
+#include "llvm/Support/Signals.h"
 #include "llvm/Support/SourceMgr.h"
 #include "llvm/Support/raw_ostream.h"
 
 using namespace mlir;
 using namespace mlir::detail;
 
+static llvm::cl::opt<bool> printStackTraceOnDiagnostic(
+    "mlir-print-stacktrace-on-diagnostic",
+    llvm::cl::desc("When a diagnostic is emitted, also print the stack trace "
+                   "as an attached note"));
+
 //===----------------------------------------------------------------------===//
 // DiagnosticArgument
 //===----------------------------------------------------------------------===//
@@ -285,6 +292,18 @@ static InFlightDiagnostic emitDiag(Location location,
   auto diag = diagEngine.emit(location, severity);
   if (!message.isTriviallyEmpty())
     diag << message;
+
+  // Add the stack trace as a note if necessary.
+  if (printStackTraceOnDiagnostic) {
+    std::string bt;
+    {
+      llvm::raw_string_ostream stream(bt);
+      llvm::sys::PrintStackTrace(stream);
+    }
+    if (!bt.empty())
+      diag.attachNote() << "diagnostic emitted with trace:\n" << bt;
+  }
+
   return diag;
 }