[clang] [llvm] [X86] Add WinCall Calling Convention and x86_64apx-windows(-gnu/-msvc) triplets (PR #215585)

[via llvm-commits]

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@@ -164,6 +164,9 @@ bool X86TargetInfo::initFeatureMap(
     for (const char *Sub :
          {"egpr", "push2pop2", "ppx", "ndd", "ccmp", "nf", "zu", "jmpabs"})
       setFeatureEnabled(Features, Sub, true);
+    // APX (EVEX) implies AVX-512, and WinCall expects every instruction to be
+    // EVEX-encoded so that no vzeroupper is needed at WinCall boundaries.
+    setFeatureEnabled(Features, "avx512f", true);
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Andarwinux wrote:

Additionally personally, when defining the ISA baseline for x86_64apx or "x86-64-v5", include GFNI and VPCLMULDQ will be useful for improving vector bitwise operations lowering, see previous GFNI vXi8 and pext/pdep work.

https://github.com/llvm/llvm-project/pull/215231#issuecomment-5238798831

https://github.com/llvm/llvm-project/pull/215585