Support accelerator data transfer

This patch provides a function interface for accelerator (GPU) devices
to be called at certain points when Carpet traverses the schedule
tree.  This can be used to copy data between the host (CPU) and the
device (GPU) as it is needed.
---
 Carpet/Carpet/interface.ccl       |   28 ++++++++++++++++++++++++++++
 Carpet/Carpet/param.ccl           |    6 ++++++
 Carpet/Carpet/src/CallFunction.cc |   12 ++++++++++++
 Carpet/Carpet/src/Comm.cc         |    8 ++++++++
 Carpet/Carpet/src/Cycle.cc        |    4 ++++
 Carpet/Carpet/src/Evolve.cc       |    2 ++
 Carpet/Carpet/src/Initialise.cc   |    2 ++
 Carpet/Carpet/src/Requirements.cc |   34 ++++++++++++++++++++++------------
 Carpet/Carpet/src/variables.cc    |    3 +++
 Carpet/Carpet/src/variables.hh    |    3 +++
 10 files changed, 90 insertions(+), 12 deletions(-)

1 files changed, 12 insertions, 0 deletions

diff --git a/Carpet/Carpet/src/CallFunction.cc b/Carpet/Carpet/src/CallFunction.cc
index 936c8525d..e0550907b 100644
--- a/Carpet/Carpet/src/CallFunction.cc
+++ b/Carpet/Carpet/src/CallFunction.cc
@@ -332,8 +332,20 @@ namespace Carpet {
       
       user_timer.start();
       timer.start();
+      if (CCTK_IsFunctionAliased("Accelerator_PreCallFunction")) {
+        Timer pre_timer("PreCall");
+        pre_timer.start();
+        Accelerator_PreCallFunction(cctkGH, attribute);
+        pre_timer.stop();
+      }
       int const res = CCTK_CallFunction (function, attribute, data);
       assert (res==0);
+      if (CCTK_IsFunctionAliased("Accelerator_PostCallFunction")) {
+        Timer post_timer("PostCall");
+        post_timer.start();
+        Accelerator_PostCallFunction(cctkGH, attribute);
+        post_timer.stop();
+      }
       timer.stop();
       user_timer.stop();