Merge branch 'azamat/theta/rm-div0-ck' into next (PR #3162)

Update machine file on theta.
Also, turn off a div-by-zero check for debug+knl+intel runs.

Fixes #3098

[BFB]

cime/config/e3sm/allactive/config_pesall.xml

@@ -8819,4 +8819,35 @@
       </pes>
     </mach>
   </grid>
+  <grid name="a%T62.+_oi%oEC60to30.*">
+    <mach name="theta">
+      <pes compset=".*MPASSI.*DOCN.+" pesize="any">
+        <comment>--res T62_oEC60to30v3 --compset DTESTM on 2 nodes</comment>
+        <ntasks>
+          <ntasks_atm>128</ntasks_atm>
+          <ntasks_lnd>128</ntasks_lnd>
+          <ntasks_rof>128</ntasks_rof>
+          <ntasks_ice>128</ntasks_ice>
+          <ntasks_ocn>128</ntasks_ocn>
+          <ntasks_cpl>128</ntasks_cpl>
+        </ntasks>
+        <nthrds>
+          <nthrds_atm>2</nthrds_atm>
+          <nthrds_lnd>2</nthrds_lnd>
+          <nthrds_rof>2</nthrds_rof>
+          <nthrds_ice>2</nthrds_ice>
+          <nthrds_ocn>2</nthrds_ocn>
+          <nthrds_cpl>2</nthrds_cpl>
+        </nthrds>
+        <rootpe>
+          <rootpe_atm>0</rootpe_atm>
+          <rootpe_lnd>0</rootpe_lnd>
+          <rootpe_rof>0</rootpe_rof>
+          <rootpe_ice>0</rootpe_ice>
+          <rootpe_ocn>0</rootpe_ocn>
+          <rootpe_cpl>0</rootpe_cpl>
+        </rootpe>
+      </pes>
+    </mach>
+  </grid>
 </config_pes>

components/cam/src/physics/clubb/lapack_wrap.F90

@@ -207,6 +207,11 @@ subroutine tridag_solve &
 
     use clubb_precision, only: &
       core_rknd ! Variable(s)
+#ifndef NDEBUG
+#if defined(ARCH_MIC_KNL) && defined(CPRINTEL)
+    use, intrinsic :: ieee_exceptions
+#endif
+#endif
 
     use error_code, only: &
       err_code,                    & ! Error Indicator
@@ -257,8 +262,20 @@ subroutine tridag_solve &
 !-----------------------------------------------------------------------
 
     if ( kind( diag(1) ) == dp ) then
+#ifndef NDEBUG
+#if defined(ARCH_MIC_KNL) && defined(CPRINTEL)
+      ! when floating-point exceptions are turned on, this call was failing with a div-by-zero on KNL with Intel/MKL. Solution 
+      ! was to turn off exceptions only here at this call (and only for machine with ARCH_MIC_KNL defined) (github 1183)
+      call ieee_set_halting_mode(IEEE_DIVIDE_BY_ZERO, .false.) ! Turn off stopping on div-by-zero only
+#endif
+#endif
       call dgtsv( ndim, nrhs, subd(2:ndim), diag, supd(1:ndim-1),  & 
                   rhs, ndim, info )
+#ifndef NDEBUG
+#if defined(ARCH_MIC_KNL) && defined(CPRINTEL)
+      call ieee_set_halting_mode(IEEE_DIVIDE_BY_ZERO, .true.) ! Turn back on stopping on div-by-zero only
+#endif
+#endif
 
     else if ( kind( diag(1) ) == sp ) then
       call sgtsv( ndim, nrhs, subd(2:ndim), diag, supd(1:ndim-1),  &