[libunwind] Multiple preprocessor fixes on PowerPC*

* Remove misnamed `PPC64_HAS_VMX` in preference of directly checking `defined(__VSX__)`.

libunwind was using "VMX" to mean "VSX". "VMX" is just another name for Altivec, while "VSX" is the vector-scalar extensions first used in POWER7. Exposing a "PPC64_HAS_VMX" define was misleading and incorrect.

* Add `defined(__ALTIVEC__)` guards around vector register operations to fix non-altivec CPUS such as the e5500.

When compiling for certain Book-E processors such as the e5500, we want to skip vector save/restore, as the Altivec registers are illegal on non-Altivec implementations.

* Add `!defined(__NO_FPRS__)` guards around traditional floating-point save/restore.

When compiling for powerpcspe, we cannot access floating point registers, as there aren't any. (The SPE on e500v2 is a 64-bit extension of the GPRs, and it doesn't have the normal floating-point registers at all.)
This fixes building for powerpcspe, although no actual handling for SPE save/restore is written yet.

Reviewed By: MaskRay, #libunwind, compnerd

Differential Revision: https://reviews.llvm.org/D91906

GitOrigin-RevId: bb1341161478dc589893cda9f808e5f5b859b5ae
5 files changed
tree: 32011bf9e50d16d13babb7ba1444a4295a2c957a
  1. .clang-format
  2. CMakeLists.txt
  3. LICENSE.TXT
  4. cmake/
  5. docs/
  6. include/
  7. src/
  8. test/