Cleanup and comment

Author: davemgreen

llvm/include/llvm/CodeGen/BasicTTIImpl.h

@@ -1905,16 +1905,15 @@ class BasicTTIImplBase : public TargetTransformInfoImplCRTPBase<T> {
       Cost += thisT()->getArithmeticInstrCost(
           BinaryOperator::LShr, RetTy, CostKind, OpInfoY,
           {OpInfoZ.Kind, TTI::OP_None});
-      // Non-constant shift amounts requires a modulo.
-      if (!OpInfoZ.isConstant()) {
-        Cost += isPowerOf2_32(RetTy->getScalarSizeInBits())
-                    ? thisT()->getArithmeticInstrCost(
-                          BinaryOperator::And, RetTy, CostKind, OpInfoZ,
-                          {TTI::OK_UniformConstantValue, TTI::OP_None})
-                    : thisT()->getArithmeticInstrCost(
-                          BinaryOperator::URem, RetTy, CostKind, OpInfoZ,
-                          {TTI::OK_UniformConstantValue, TTI::OP_None});
-      }
+      // Non-constant shift amounts requires a modulo. If the typesize is a
+      // power-2 then this will be converted to an and, otherwise it will use a
+      // urem.
+      if (!OpInfoZ.isConstant())
+        Cost += thisT()->getArithmeticInstrCost(
+            isPowerOf2_32(RetTy->getScalarSizeInBits()) ? BinaryOperator::And
+                                                        : BinaryOperator::URem,
+            RetTy, CostKind, OpInfoZ,
+            {TTI::OK_UniformConstantValue, TTI::OP_None});
       // For non-rotates (X != Y) we must add shift-by-zero handling costs.
       if (X != Y) {
         Type *CondTy = RetTy->getWithNewBitWidth(1);