Revert "r293343 - [ubsan] Sanity-check shift amounts before truncation
(fixes PR27271)"

After r293343 clang fails to compile itself with -fsanitize=undefined (
http://lab.llvm.org:8080/green/job/clang-stage2-cmake-RgSan_build/).

rdar://30259929

llvm-svn: 293475
diff --git a/clang/lib/CodeGen/CGExprScalar.cpp b/clang/lib/CodeGen/CGExprScalar.cpp
index 40d949d..1b85c45 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -2751,8 +2751,8 @@
            isa<llvm::IntegerType>(Ops.LHS->getType())) {
     CodeGenFunction::SanitizerScope SanScope(&CGF);
     SmallVector<std::pair<Value *, SanitizerMask>, 2> Checks;
-    llvm::Value *WidthMinusOne = GetWidthMinusOneValue(Ops.LHS, Ops.RHS);
-    llvm::Value *ValidExponent = Builder.CreateICmpULE(Ops.RHS, WidthMinusOne);
+    llvm::Value *WidthMinusOne = GetWidthMinusOneValue(Ops.LHS, RHS);
+    llvm::Value *ValidExponent = Builder.CreateICmpULE(RHS, WidthMinusOne);
 
     if (SanitizeExponent) {
       Checks.push_back(