From 96eb38418bcc2e11f9b991629231451dc8c19555 Mon Sep 17 00:00:00 2001
From: Mehdi Amini <joker.eph@gmail.com>
Date: Sun, 5 Apr 2020 03:01:21 +0000
Subject: [PATCH] Make the AsmPrinter print "<<NULL TYPE>>" instead of crashing
 on null types

Even if this indicates in general a problem at call sites, the printer
is used for debugging and avoiding crashing is friendlier for example
when used in diagnostics or other printer.

Differential Revision: https://reviews.llvm.org/D77481
---
 mlir/lib/IR/AsmPrinter.cpp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/mlir/lib/IR/AsmPrinter.cpp b/mlir/lib/IR/AsmPrinter.cpp
index bc680cf..987c6b9 100644
--- a/mlir/lib/IR/AsmPrinter.cpp
+++ b/mlir/lib/IR/AsmPrinter.cpp
@@ -1490,6 +1490,11 @@ void ModulePrinter::printDenseElementsAttr(DenseElementsAttr attr,
 }
 
 void ModulePrinter::printType(Type type) {
+  if (!type) {
+    os << "<<NULL TYPE>>";
+    return;
+  }
+
   // Check for an alias for this type.
   if (state) {
     StringRef alias = state->getAliasState().getTypeAlias(type);
-- 
2.7.4