[SCEV] Remove mul handling from BuildConstantFromSCEV()

We can't support this once mul constant expressions are removed,
and this is not useful in any practical sense (as this code is
primarily intended for GEP expressions).

Author: nikic

llvm/lib/Analysis/ScalarEvolution.cpp

@@ -9688,18 +9688,7 @@ static Constant *BuildConstantFromSCEV(const SCEV *V) {
     }
     return C;
   }
-  case scMulExpr: {
-    const SCEVMulExpr *SM = cast<SCEVMulExpr>(V);
-    Constant *C = nullptr;
-    for (const SCEV *Op : SM->operands()) {
-      assert(!Op->getType()->isPointerTy() && "Can't multiply pointers");
-      Constant *OpC = BuildConstantFromSCEV(Op);
-      if (!OpC)
-        return nullptr;
-      C = C ? ConstantExpr::getMul(C, OpC) : OpC;
-    }
-    return C;
-  }
+  case scMulExpr:
   case scSignExtend:
   case scZeroExtend:
   case scUDivExpr: