Change the device library to use CUDA runtime API

[alexrlongne]

Background

• Our CUDA device helper classes used a the older CUDA driver API, which is not recommended for new projects. The new runtime API is much simpler and doesn't require explicit management of modules or contexts. It also provides some very nice helper functions to diagnose runtime errors and query the device. This PR changes the GPU_Device helper class to use these newer functions. It also demonstrates how to compile a library of CUDA functions that can be called from either the host or device. To linking to a library of CUDA device functions the target library must be static. This required a slight change to the add_component_library CMake macro.

Purpose of Pull Request

• Completes Redmine Issue #1429

Description of changes

• Add a simple CUDA compilation step during configure to determine the appropriate architecture flags
• Allow add_component_library to accept a library type different than the DRACO_LIBRARY_TYPE variable
• Change the GPU_Device class to use the newer CUDA Runtime API
• Remove the GPU_Module class (explicit module and contexts are not necessary in the Runtime API)
• Remove "EXTERN C" decorations (these are also no longer necessary in the Runtime API since functions do not need to be loaded explicitly)
• Add a test that shows an example of calling code from both the host and device
• Consolidate calls to simple GPU test kernels into a "basic_kernels" header and implementation file
• Compile auxiliary GPU test code into a static library callable by the individual gpu tests

Status

• Reference:
  • Pre-Merge Code Review
  • CDash Status
• Checks
  • Travis CI checks pass
  • Code coverage does not decrease
  • Valgrind test passes
  • Toss3 checks pass
  • Trinitite checks pass
  • Code reviewed/approved, sufficient DbC checks, testing, documentation

[alexrlongne]

@KineticTheory @jhchang-lanl I'm open to any idea on how to name GPU tests, libraries, files etc. Just let me know and I'll change it.

[codecov]

Codecov Report

Merging #589 into develop will decrease coverage by 1.6%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##           develop    #589     +/-   ##
=========================================
- Coverage     93.7%     92%   -1.7%     
=========================================
  Files          377     364     -13     
  Lines        17665   16933    -732     
=========================================
- Hits         16554   15581    -973     
- Misses        1111    1352    +241

[codecov]

Codecov Report

Merging #589 into develop will increase coverage by <.1%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##           develop    #589     +/-   ##
=========================================
+ Coverage     93.7%   93.7%   +<.1%     
=========================================
  Files          377     380      +3     
  Lines        17665   17791    +126     
=========================================
+ Hits         16554   16673    +119     
- Misses        1111    1118      +7

[KineticTheory]

Overall, this looks pretty good. In fact, we might use the planning meeting on Monday to read through this code. It will be instructive for all of us.

[KineticTheory]

@KineticTheory @clevelam Is email from gitlab working

[KineticTheory]

Some weirdness...

Preprocessing /home/travis/Draco/src/device/GPU_Device.hh:55: \
error: included file device/test/gpu_hello_driver_api.cc is not found. \
Check your EXAMPLE_PATH (warning treated as error, aborting now)

I'll help you fix this one.

[alexrlongne]

@KineticTheory I've tried to address all of your comments and the Travis CI is passing. This should be ready for merge once the CDash is clean.