From 5112b71126a133b744b11b50d60fcb89d005513d Mon Sep 17 00:00:00 2001
From: Aditya Nandakumar <aditya_nandakumar@apple.com>
Date: Mon, 9 Sep 2019 22:51:41 +0000
Subject: [PATCH] [GlobalISel]: Fix a bug where we could dereference None

getConstantVRegVal returns None when dealing with constants > 64 bits.
Don't assume we always have a value in GISelKnownBits.

llvm-svn: 371465
---
 llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp b/llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp
index 7db6465..c0391f7 100644
--- a/llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp
@@ -140,6 +140,8 @@ void GISelKnownBits::computeKnownBitsImpl(Register R, KnownBits &Known,
   }
   case TargetOpcode::G_CONSTANT: {
     auto CstVal = getConstantVRegVal(R, MRI);
+    if (!CstVal)
+      break;
     Known.One = *CstVal;
     Known.Zero = ~Known.One;
     break;
-- 
2.7.4