[CHERI] Enable SCEV for CHERI pointers.

Per communication with CHERI upstream, this is expected to work at this point.

Author: resistor

llvm/lib/Analysis/ScalarEvolution.cpp

@@ -6296,12 +6296,6 @@ const SCEV *ScalarEvolution::createNodeForGEP(GEPOperator *GEP) {
   assert(GEP->getSourceElementType()->isSized() &&
          "GEP source element type must be sized");
 
-  const DataLayout &DL = F.getParent()->getDataLayout();
-  // FIXME: Ideally, we should teach Scalar Evolution to
-  // understand fat pointers.
-  if (DL.isFatPointer(GEP->getPointerOperandType()->getPointerAddressSpace()))
-    return getUnknown(GEP);
-
   SmallVector<const SCEV *, 4> IndexExprs;
   for (Value *Index : GEP->indices())
     IndexExprs.push_back(getSCEV(Index));