[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 · Sep 9, 2019 · 5112b71 · 5112b71
1 parent 2ca7370
commit 5112b71
Showing 1 changed file with 2 additions and 0 deletions.
diff --git 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;