Fix UB in benchmakrs

This kind of fix would be not be good for
production code, but it does not change the
essenset of benchmark, so should be good
enough here.

ix[k] can be 0 causing negative index on array access.
p[ip][0] can be outside of Index_type.

Differential Revision: https://reviews.llvm.org/D157348

Author: vitalybuka

MicroBenchmarks/LCALS/SubsetCLambdaLoops/LambdaSubsetCbenchmarks.cxx

@@ -379,16 +379,16 @@ static void BM_PIC_2D_LAMBDA(benchmark::State& state) {
       forall<exec_policy>(0, state.range(0),
       [&] (Index_type ip) {
          Index_type i1, j1, i2, j2;
-         i1 = (Index_type) p[ip][0];
-         j1 = (Index_type) p[ip][1];
+         i1 = (Index_type) (long long) p[ip][0];
+         j1 = (Index_type) (long long) p[ip][1];
          i1 &= 64-1;
          j1 &= 64-1;
          p[ip][2] += b[j1][i1];
          p[ip][3] += c[j1][i1];
          p[ip][0] += p[ip][2];
          p[ip][1] += p[ip][3];
-         i2 = (Index_type) p[ip][0];
-         j2 = (Index_type) p[ip][1];
+         i2 = (Index_type) (long long) p[ip][0];
+         j2 = (Index_type) (long long) p[ip][1];
          i2 = ( i2 & 64-1 ) ;
          j2 = ( j2 & 64-1 ) ;
          p[ip][0] += y[i2+32];
@@ -435,8 +435,8 @@ static void BM_PIC_1D_LAMBDA(benchmark::State& state) {
          xx[k] = 0.0;
          ix[k] = (Index_type) grd[k];
          xi[k] = (Real_type) ix[k];
-         ex1[k] = ex[ ix[k] - 1 ];
-         dex1[k] = dex[ ix[k] - 1 ];
+         ex1[k] = ix[k] ? ex[ ix[k] - 1 ] : 0;
+         dex1[k] = ix[k] ? dex[ ix[k] - 1 ] : 0;
       } );
 
       forall<exec_policy>(0, state.range(0),

MicroBenchmarks/LCALS/SubsetCRawLoops/RawSubsetCbenchmarks.cxx

@@ -549,16 +549,16 @@ static void BM_PIC_2D_RAW(benchmark::State& state) {
 
       for (Index_type ip=0 ; ip< state.range(0) ; ip++ ) {
          Index_type i1, j1, i2, j2;
-         i1 = (Index_type) p[ip][0];
-         j1 = (Index_type) p[ip][1];
+         i1 = (Index_type) (long long) p[ip][0];
+         j1 = (Index_type) (long long) p[ip][1];
          i1 &= 64-1;
          j1 &= 64-1;
          p[ip][2] += b[j1][i1];
          p[ip][3] += c[j1][i1];
          p[ip][0] += p[ip][2];
          p[ip][1] += p[ip][3];
-         i2 = (Index_type) p[ip][0];
-         j2 = (Index_type) p[ip][1];
+         i2 = (Index_type) (long long) p[ip][0];
+         j2 = (Index_type) (long long) p[ip][1];
          i2 = ( i2 & 64-1 ) ;
          j2 = ( j2 & 64-1 ) ;
          p[ip][0] += y[i2+32];
@@ -631,8 +631,8 @@ static void BM_PIC_1D_RAW(benchmark::State& state) {
          xx[k] = 0.0;
          ix[k] = (Index_type) grd[k];
          xi[k] = (Real_type) ix[k];
-         ex1[k] = ex[ ix[k] - 1 ];
-         dex1[k] = dex[ ix[k] - 1 ];
+         ex1[k] = ix[k] ? ex[ ix[k] - 1 ] : 0;
+         dex1[k] = ix[k] ? dex[ ix[k] - 1 ] : 0;
       }
 
       for (Index_type k=0 ; k< state.range(0) ; k++ ) {