diff --git a/public/c++/VectorPairHMM/LoadTimeInitializer.cc b/public/c++/VectorPairHMM/LoadTimeInitializer.cc
index fb640ef88..9b56fa9ad 100644
--- a/public/c++/VectorPairHMM/LoadTimeInitializer.cc
+++ b/public/c++/VectorPairHMM/LoadTimeInitializer.cc
@@ -7,6 +7,10 @@ LoadTimeInitializer g_load_time_initializer;
 LoadTimeInitializer::LoadTimeInitializer()		//will be called when library is loaded
 {
   ConvertChar::init();
+#ifndef DISABLE_FTZ
+  //Very important to get good performance - enable FTZ, converts denormals to 0
+  _MM_SET_FLUSH_ZERO_MODE(_MM_FLUSH_ZERO_ON);
+#endif
   m_sumNumReads = 0;
   m_sumSquareNumReads = 0;
   m_sumNumHaplotypes = 0;
diff --git a/public/c++/VectorPairHMM/Makefile b/public/c++/VectorPairHMM/Makefile
index 35b38e291..0b564d033 100644
--- a/public/c++/VectorPairHMM/Makefile
+++ b/public/c++/VectorPairHMM/Makefile
@@ -13,15 +13,18 @@ CXX=icc
 
 LDFLAGS=-lm -lrt $(OMPLDFLAGS)
 
-#USE_PAPI=1
 PAPI_DIR=/home/karthikg/softwares/papi-5.3.0
 ifdef USE_PAPI
   ifeq ($(USE_PAPI),1)
-    COMMON_COMPILATION_FLAGS+=-I$(PAPI_DIR)/include
+    COMMON_COMPILATION_FLAGS+=-I$(PAPI_DIR)/include -DUSE_PAPI
     LDFLAGS+=-L$(PAPI_DIR)/lib -lpapi
   endif
 endif
 
+ifdef DISABLE_FTZ
+  COMMON_COMPILATION_FLAGS+=-DDISABLE_FTZ -no-ftz
+endif
+
 BIN=libVectorLoglessPairHMM.so pairhmm-template-main checker
 #BIN=checker
 
diff --git a/public/c++/VectorPairHMM/baseline.cc b/public/c++/VectorPairHMM/baseline.cc
index d92a21ecf..eb233d5c3 100644
--- a/public/c++/VectorPairHMM/baseline.cc
+++ b/public/c++/VectorPairHMM/baseline.cc
@@ -1,6 +1,7 @@
 #include "headers.h"
 #include "template.h"
-extern uint64_t exceptions_array[128];
+#include "utils.h"
+
 template<class NUMBER>
 NUMBER compute_full_prob(testcase *tc, NUMBER *before_last_log = NULL)
 {
@@ -66,18 +67,22 @@ NUMBER compute_full_prob(testcase *tc, NUMBER *before_last_log = NULL)
 				distm = distm/3;
 
 
-	  		//feclearexcept(FE_ALL_EXCEPT);
+                        //feclearexcept(FE_ALL_EXCEPT);
 	  		M[r][c] = distm * (M[r-1][c-1] * p[r][MM] + X[r-1][c-1] * p[r][GapM] + Y[r-1][c-1] * p[r][GapM]);
-	  		//M[r][c] = (M[r-1][c-1] * p[r][MM] + X[r-1][c-1] * p[r][GapM] + Y[r-1][c-1] * p[r][GapM]);
-	  		//STORE_FP_EXCEPTIONS(flagp, exceptions_array);
+                        //STORE_FP_EXCEPTIONS(flagp, exceptions_array);
 
-	  		//feclearexcept(FE_ALL_EXCEPT);
+                        //feclearexcept(FE_ALL_EXCEPT);
 	  		X[r][c] = M[r-1][c] * p[r][MX] + X[r-1][c] * p[r][XX];
-	  		//STORE_FP_EXCEPTIONS(flagp, exceptions_array);
+                        //STORE_FP_EXCEPTIONS(flagp, exceptions_array);
 
-	  		//feclearexcept(FE_ALL_EXCEPT);
+                        //feclearexcept(FE_ALL_EXCEPT);
 	  		Y[r][c] = M[r][c-1] * p[r][MY] + Y[r][c-1] * p[r][YY];
-	  		//STORE_FP_EXCEPTIONS(flagp, exceptions_array);
+                        //STORE_FP_EXCEPTIONS(flagp, exceptions_array);
+
+                        //CONVERT_AND_PRINT(M[r][c]);
+                        //CONVERT_AND_PRINT(X[r][c]);
+                        //CONVERT_AND_PRINT(Y[r][c]);
+
 		}
 
   	for (c = 0; c < COLS; c++)
diff --git a/public/c++/VectorPairHMM/headers.h b/public/c++/VectorPairHMM/headers.h
index feb687660..9e4600136 100644
--- a/public/c++/VectorPairHMM/headers.h
+++ b/public/c++/VectorPairHMM/headers.h
@@ -27,14 +27,19 @@
 #include <cmath>
 #include <fenv.h>
 
-#define STORE_FP_EXCEPTIONS(flagp, exceptions_array)                                                  \
-  fegetexceptflag(&flagp, FE_OVERFLOW | FE_UNDERFLOW | FE_DIVBYZERO | FE_INVALID | __FE_DENORM);      \
+extern uint64_t exceptions_array[128];
+extern FILE* g_debug_fptr;
+#define STORE_FP_EXCEPTIONS(flagp, exceptions_array)                                    \
+  fegetexceptflag(&flagp, FE_ALL_EXCEPT | __FE_DENORM);                                 \
   exceptions_array[FE_INVALID] += ((flagp & FE_INVALID));                               \
   exceptions_array[__FE_DENORM] += ((flagp & __FE_DENORM) >> 1);                        \
   exceptions_array[FE_DIVBYZERO] += ((flagp & FE_DIVBYZERO) >> 2);                      \
   exceptions_array[FE_OVERFLOW] += ((flagp & FE_OVERFLOW) >> 3);                        \
   exceptions_array[FE_UNDERFLOW] += ((flagp & FE_UNDERFLOW) >> 4);                      \
-  feclearexcept(FE_ALL_EXCEPT);                 
+  feclearexcept(FE_ALL_EXCEPT | __FE_DENORM);                 
 
+#define CONVERT_AND_PRINT(X)                    \
+  g_converter.f = (X);                          \
+  fwrite(&(g_converter.i),4,1,g_debug_fptr);    \
 
 #endif
diff --git a/public/c++/VectorPairHMM/utils.cc b/public/c++/VectorPairHMM/utils.cc
index 4625537bd..419b2d4ce 100644
--- a/public/c++/VectorPairHMM/utils.cc
+++ b/public/c++/VectorPairHMM/utils.cc
@@ -45,7 +45,7 @@ uint64_t get_machine_capabilities()
 
 void initialize_function_pointers(uint64_t mask)
 {
-  //mask = 0;
+  //mask = 0ull;
   if(is_avx_supported() && (mask & (1<< AVX_CUSTOM_IDX)))
   {
     cout << "Using AVX accelerated implementation of PairHMM\n";
@@ -287,16 +287,23 @@ uint64_t diff_time(struct timespec& prev_time)
 }
 
 //#define USE_PAPI
+//#define COUNT_EXCEPTIONS
+//#define CHECK_RESULTS
+#define CHECK_UNDERFLOW 1
 #ifdef USE_PAPI
 #include "papi.h"
 #define NUM_PAPI_COUNTERS 4
 #endif
 
+IF_32 g_converter;
+FILE* g_debug_fptr = 0;
 uint64_t exceptions_array[128];
 void do_compute(char* filename)
 {
-  memset(exceptions_array, 0, 128*sizeof(uint64_t));
-  _MM_SET_FLUSH_ZERO_MODE(_MM_FLUSH_ZERO_ON);
+  //g_debug_fptr = fopen("/mnt/app_hdd/scratch/karthikg/dump.log","w");
+  //assert(g_debug_fptr);
+  for(unsigned i=0;i<128;++i)
+    exceptions_array[i] = 0ull;
   //assert(feenableexcept(FE_DIVBYZERO | FE_INVALID) >= 0);
 #ifdef USE_PAPI
   PAPI_num_counters();
@@ -310,11 +317,11 @@ void do_compute(char* filename)
   int events[NUM_PAPI_COUNTERS] = { 0, 0, 0, 0 };
     //assert(PAPI_event_name_to_code("ICACHE:IFETCH_STALL",&(events[2])) == PAPI_OK);
   //assert(PAPI_event_name_to_code("MACHINE_CLEARS:e",&(events[3])) == PAPI_OK);
-  char* eventnames[NUM_PAPI_COUNTERS]=  { "instructions", "cycles", "ifetch_stall", "store_misses" };
+  char* eventnames[NUM_PAPI_COUNTERS]=  { "instructions", "cycles", "fp_assists", "idq_ms_cycles" };
   assert(PAPI_event_name_to_code("ix86arch::INSTRUCTION_RETIRED",&(events[0])) == PAPI_OK);
   assert(PAPI_event_name_to_code("UNHALTED_REFERENCE_CYCLES",&(events[1])) == PAPI_OK);
-  assert(PAPI_event_name_to_code("ICACHE:IFETCH_STALL",   &(events[2])) == PAPI_OK);
-  assert(PAPI_event_name_to_code("perf::L1-DCACHE-STORE-MISSES",   &(events[3])) == PAPI_OK);
+  assert(PAPI_event_name_to_code("FP_ASSIST:ANY",   &(events[2])) == PAPI_OK);
+  assert(PAPI_event_name_to_code("IDQ:MS_UOPS_CYCLES",   &(events[3])) == PAPI_OK);
   long long values[NUM_PAPI_COUNTERS] = { 0, 0, 0, 0 };
   long long accum_values[NUM_PAPI_COUNTERS] = { 0, 0, 0, 0 };
 
@@ -353,6 +360,9 @@ void do_compute(char* filename)
 
   testcase tc_in;
   int break_value = 0;
+  uint64_t fp_single_exceptions_reexecute = 0;
+  uint64_t fp_single_exceptions_continue = 0;
+  uint64_t num_double_executions = 0;
   while(1)
   {
     break_value = use_old_read_testcase ? read_testcase(&tc_in, fptr) : 
@@ -373,13 +383,38 @@ void do_compute(char* filename)
       for(unsigned i=0;i<num_testcases;++i)
       {
         double result = 0;
+#ifdef COUNT_EXCEPTIONS
+        fexcept_t flagp = 0;
+        feclearexcept(FE_ALL_EXCEPT | __FE_DENORM);                 
+#endif
         float result_avxf = g_compute_full_prob_float(&(tc_vector[i]), 0);
-        if (result_avxf < MIN_ACCEPTED) {
+        //CONVERT_AND_PRINT(result_avxf);
+#ifdef COUNT_EXCEPTIONS
+        STORE_FP_EXCEPTIONS(flagp, exceptions_array);
+        bool fp_exception =  ((flagp & (FE_UNDERFLOW|FE_OVERFLOW|FE_INVALID)) != 0);
+#endif
+#ifdef CHECK_UNDERFLOW
+        if (result_avxf < MIN_ACCEPTED)
+#else
+        if(false)
+#endif
+        {
+#ifdef COUNT_EXCEPTIONS
+          if(fp_exception)
+            ++fp_single_exceptions_reexecute;
+#endif
           double result_avxd = g_compute_full_prob_double(&(tc_vector[i]), 0);
           result = log10(result_avxd) - log10(ldexp(1.0, 1020.0));
+          ++num_double_executions;
         }
         else
+        {
+#ifdef COUNT_EXCEPTIONS
+          if(fp_exception)
+            ++fp_single_exceptions_continue;
+#endif
           result = (double)(log10f(result_avxf) - log10f(ldexpf(1.f, 120.f)));
+        }
         results_vec[i] = result;
       }
 #ifdef USE_PAPI
@@ -392,7 +427,7 @@ void do_compute(char* filename)
         accum_values[k] += values[k];
 #endif
 
-#if 0
+#ifdef CHECK_RESULTS
 #pragma omp parallel for schedule(dynamic,chunk_size)
       for(unsigned i=0;i<num_testcases;++i)
       {
@@ -419,6 +454,8 @@ void do_compute(char* filename)
           all_ok = false;
         }
       }
+#else
+      all_ok = false;
 #endif
       for(unsigned i=0;i<num_testcases;++i)
       {
@@ -457,11 +494,16 @@ void do_compute(char* filename)
     fclose(fptr);
   else
     ifptr.close();
-  //cout << "Exceptions "<<exceptions_array[FE_INVALID]<< " "
-    //<<exceptions_array[__FE_DENORM]<< " "
-    //<<exceptions_array[FE_DIVBYZERO]<< " "
-    //<<exceptions_array[FE_OVERFLOW]<< " "
-    //<<exceptions_array[FE_UNDERFLOW]<< " "
-    //<<exceptions_array[FE_INEXACT]<< "\n";
+#ifdef COUNT_EXCEPTIONS
+  cout << "Exceptions "
+    <<"invalid : "<<exceptions_array[FE_INVALID]<< " "
+    <<"denormal : "<<exceptions_array[__FE_DENORM]<< " "
+    <<"div_by_0 : "<<exceptions_array[FE_DIVBYZERO]<< " "
+    <<"overflow : "<<exceptions_array[FE_OVERFLOW]<< " "
+    <<"underflow : "<<exceptions_array[FE_UNDERFLOW]<< "\n";
+  cout << "Single precision FP exceptions continuations "<<fp_single_exceptions_continue<<" re-executions "<<fp_single_exceptions_reexecute<<"\n";
+#endif
+  cout << "Num double executions "<<num_double_executions<<"\n";
 
+  //fclose(g_debug_fptr);
 }
diff --git a/public/c++/VectorPairHMM/utils.h b/public/c++/VectorPairHMM/utils.h
index f6ecc67ed..edf4858eb 100644
--- a/public/c++/VectorPairHMM/utils.h
+++ b/public/c++/VectorPairHMM/utils.h
@@ -39,6 +39,7 @@ enum ProcessorCapabilitiesEnum
 uint64_t get_machine_capabilities();
 void initialize_function_pointers(uint64_t mask=ENABLE_ALL_HARDWARE_FEATURES);
 
+extern IF_32 g_converter;
 void do_compute(char* filename);
 
 #endif