SystemZ: Avoid left shifting negative values (it's UB)

Found by ubsan. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@240420 91177308-0d34-0410-b5e6-96231b3b80d8
CIB · Jun 23, 2015 · 3800e76 · 3800e76
1 parent 896353d
commit 3800e76
Showing 1 changed file with 4 additions and 4 deletions.
diff --git a/lib/Target/SystemZ/SystemZISelLowering.cpp b/lib/Target/SystemZ/SystemZISelLowering.cpp
@@ -2005,17 +2005,17 @@ static Comparison getIntrinsicCmp(SelectionDAG &DAG, unsigned Opcode,
   else if (Cond == ISD::SETLT || Cond == ISD::SETULT)
     // bits above bit 3 for CC==0 (always false), bits above bit 0 for CC==3,
     // always true for CC>3.
-    C.CCMask = CC < 4 ? -1 << (4 - CC) : -1;
+    C.CCMask = CC < 4 ? ~0U << (4 - CC) : -1;
   else if (Cond == ISD::SETGE || Cond == ISD::SETUGE)
     // ...and the inverse of that.
-    C.CCMask = CC < 4 ? ~(-1 << (4 - CC)) : 0;
+    C.CCMask = CC < 4 ? ~(~0U << (4 - CC)) : 0;
   else if (Cond == ISD::SETLE || Cond == ISD::SETULE)
     // bit 3 and above for CC==0, bit 0 and above for CC==3 (always true),
     // always true for CC>3.
-    C.CCMask = CC < 4 ? -1 << (3 - CC) : -1;
+    C.CCMask = CC < 4 ? ~0U << (3 - CC) : -1;
   else if (Cond == ISD::SETGT || Cond == ISD::SETUGT)
     // ...and the inverse of that.
-    C.CCMask = CC < 4 ? ~(-1 << (3 - CC)) : 0;
+    C.CCMask = CC < 4 ? ~(~0U << (3 - CC)) : 0;
   else
     llvm_unreachable("Unexpected integer comparison type");
   C.CCMask &= CCValid;