[PATCH 0/4] Fix building tools/tests/x86_emulator with clang-21

[Edwin Török <edwin.torok@xxxxxxxxxx>]

While working on another patch series I noticed that `clang-21` cannot
build `tools/tests/x86_emulator`. Once I fixed that `xmm0` related tests
failed, because `clang` doesn't support `-ffixed-xmm0`.

This series fixes building and running the test with `clang`.

There might still be some latent bugs in the tests though, i.e. `xmm0` may not
be the only reason it fails on clang: the `fxsave` tests have
2 overlapping areas of memory at `res + 0x80`, and `res + 0x100` of length 
`0x200`.
Instead the 2nd area should start at `0x280`, and the memset should
clear an area of `0x480`.
I didn't attempt to fix all those, because attempting to do so caused
the tests to start failing on GCC.

For convenience this patch series is also available at:
https://gitlab.com/xen-project/people/edwintorok/xen/-/compare/staging...private%2Fedvint%2Femulator?from_project_id=2336572
https://gitlab.com/xen-project/people/edwintorok/xen/-/pipelines/2343355874

Edwin Török (4):
  tools/tests/x86_emulator: fix 'shifting a negative signed value is
    undefined'
  tools/tests/x86_emulator: avoid duplicating loop body
  tools/tests/x86_emulator: fix build on clang-21
  tools/tests/x86_emulator: disable xmm* tests on clang

 tools/tests/x86_emulator/Makefile            |  1 +
 tools/tests/x86_emulator/test_x86_emulator.c | 48 +++++++++++++++++++-
 2 files changed, 47 insertions(+), 2 deletions(-)

-- 
2.47.3