Use the `%clang_cc1` substitution consistently across the test suite,
replacing inline `%clang -cc1` invocations, except for one Preprocessor
test where this is causing breakage. This is necessary to ensure that
additional parameters passed via `%clang` do not interfere with `-cc1`
that must always be passed as the first command-line argument.
Remove the additional substitution blocking `%clang_cc1` use in Driver
tests. It has been added in 2013 and was supposed to prevent tests
calling `clang -cc1` from being added to Driver. The state of the test
suite proves that it did not succeed at all.
Differential Revision: https://reviews.llvm.org/D134880
Two new dxc mode options -O and -Od are added for dxc mode.
-O is just alias of existing cc1 -O option.
-Od will be lowered into -O0 and -dxc-opt-disable.
-dxc-opt-disable is cc1 option added to for build ShaderFlags.
Reviewed By: beanz
Differential Revision: https://reviews.llvm.org/D128845
