g++ timer not compatible with DPC++ Intel compiler

I've got an HPCCG file I've been trying to compile. I want to compile it with the Intel oneAPI compiler which it does successfully but the results produced suggest the timer implementation isn't working. I noticed that it works when I use the g++ compiler. This is the timer implementation source code below:

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//               HPCCG: Simple Conjugate Gradient Benchmark Code
//                 Copyright (2006) Sandia Corporation
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/////////////////////////////////////////////////////////////////////////

// Function to return time in seconds.
// If compiled with no flags, return CPU time (user and system).
// If compiled with -DWALL, returns elapsed time.

/////////////////////////////////////////////////////////////////////////
#ifdef USING_MPI
#include <mpi.h> // If this routine is compiled with -DUSING_MPI
                 // then include mpi.h
double mytimer(void)
{
   return(MPI_Wtime());
}


#elif defined(UseClock)

#include <time.hpp>
double mytimer(void)
{
   clock_t t1;
   static clock_t t0=0;
   static double CPS = CLOCKS_PER_SEC;
   double d;

   if (t0 == 0) t0 = clock();
   t1 = clock() - t0;
   d = t1 / CPS;
   return(d);
}

#elif defined(WALL)

#include <cstdlib>
#include <sys/time.h>
#include <sys/resource.h>
double mytimer(void)
{
   struct timeval tp;
   static long start=0, startu;
   if (!start)
   {
      gettimeofday(&tp, NULL);
      start = tp.tv_sec;
      startu = tp.tv_usec;
      return(0.0);
   }
   gettimeofday(&tp, NULL);
   return( ((double) (tp.tv_sec - start)) + (tp.tv_usec-startu)/1000000.0 );
}

#elif defined(UseTimes)

#include <cstdlib>
#include <sys/times.h>
#include <unistd.h>
double mytimer(void)
{
   struct tms ts;
   static double ClockTick=0.0;

   if (ClockTick == 0.0) ClockTick = (double) sysconf(_SC_CLK_TCK);
   times(&ts);
   return( (double) ts.tms_utime / ClockTick );
}

#else

#include <cstdlib>
#include <sys/time.h>
#include <sys/resource.h>
double mytimer(void)
{
   struct rusage ruse;
   getrusage(RUSAGE_SELF, &ruse);
   return( (double)(ruse.ru_utime.tv_sec+ruse.ru_utime.tv_usec / 1000000.0) );
}

#endif

I tried compiling this with icpx and these were my results:

#********** Performance Summary (times in sec) ***********: 
Time Summary: 
  Total   : 0
  DDOT    : 0
  WAXPBY  : 0
  SPARSEMV: 0
FLOPS Summary: 
  Total   : 9.536e+06
  DDOT    : 596000
  WAXPBY  : 894000
  SPARSEMV: 8.046e+06
MFLOPS Summary: 
  Total   : inf
  DDOT    : inf
  WAXPBY  : inf
  SPARSEMV: inf

And when I change the compiler to g++. These are my results

#********** Performance Summary (times in sec) ***********: 
Time Summary: 
  Total   : 0.018251
  DDOT    : 0.001142
  WAXPBY  : 0.001825
  SPARSEMV: 0.014805
FLOPS Summary: 
  Total   : 9.536e+06
  DDOT    : 596000
  WAXPBY  : 894000
  SPARSEMV: 8.046e+06
MFLOPS Summary: 
  Total   : 522.492
  DDOT    : 521.891
  WAXPBY  : 489.863
  SPARSEMV: 543.465