SYCL compilations initiated by the driver will spawn off one or more
frontend compilation jobs (one for device and one for host). This patch
reworks the driver options to make upstreaming this from the downstream
SYCL fork easier.
This patch introduces a language option to identify host executions
(SYCLIsHost) and a -cc1 frontend option to enable this mode. -fsycl and
-fno-sycl become driver-only options that are rejected when passed to
-cc1. This is because the frontend and beyond should be looking at
whether the user is doing a device or host compilation specifically.
Because the frontend should only ever be in one mode or the other,
-fsycl-is-device and -fsycl-is-host are mutually exclusive options.
SYCL device compiler (similar to other SPMD compilers) assumes that
functions are convergent by default to avoid invalid transformations.
This attribute can be removed if compiler can prove that function does
not have convergent operations.
Reviewed By: Naghasan
Differential Revision: https://reviews.llvm.org/D87282
Alexey Bader