Also get rid of explicitly specified '-march' values for old architectures.
This simplifies %ptxas-verify statements.
After the change, we can potentially miss cases where a new functionality
is added to the architecture without appropriate checks in the
backend. On the other hand, this is mostly true for old architectures
that have been thoroughly tested.
Differential Revision: https://reviews.llvm.org/D141736
ptxas is a proprietary compiler from Nvidia that can compile PTX to
machine code (SASS). It has a lot of diagnostics to catch errors
in PTX, which can be used to verify PTX output from llc.
Set -DPXTAS_EXECUTABLE=/path/to/ptxas CMake option to enable it.
If this option is not set, then ptxas is substituted to true which
effectively disables all ptxas RUN lines.
LLVM_PTXAS_EXECUTABLE environment variable takes precedence over
the CMake option, and allows to override ptxas executable that is used for LIT
without complete re-configuration.
Differential Revision: https://reviews.llvm.org/D121727
