[clang] [llvm] [AArch64] Fix _sys implemantation and MRS/MSR Sema checks (PR #187290)

[Daniel Paoliello via cfe-commits]

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@@ -11,7 +11,7 @@
 
 // From winnt.h
 // op0=1 encodings, use with __sys
-#define ARM64_SYSINSTR(op0, op1, crn, crm, op2) \
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dpaoliello wrote:

Same comment about winnt.h here: please don't change the signature of this.

https://github.com/llvm/llvm-project/pull/187290