[cfi] Fix LowerBitSets on 32-bit targets.

This code attempts to truncate IntPtrTy to i32, which may be the same
type.

llvm-svn: 256205
diff --git a/llvm/lib/Transforms/IPO/LowerBitSets.cpp b/llvm/lib/Transforms/IPO/LowerBitSets.cpp
index 65d082b..7b51574 100644
--- a/llvm/lib/Transforms/IPO/LowerBitSets.cpp
+++ b/llvm/lib/Transforms/IPO/LowerBitSets.cpp
@@ -683,7 +683,7 @@
   ConstantInt *DispOffset =
       ConstantInt::get(IntPtrTy, Distance * kX86JumpTableEntrySize + 5);
   Constant *OffsetedDisp = ConstantExpr::getSub(Disp, DispOffset);
-  OffsetedDisp = ConstantExpr::getTrunc(OffsetedDisp, Int32Ty);
+  OffsetedDisp = ConstantExpr::getTruncOrBitCast(OffsetedDisp, Int32Ty);
 
   ConstantInt *Int3 = ConstantInt::get(Int8Ty, kInt3Code);