[llvm] [AArch64] Initial compiler support for SVE unwind on Windows. (PR #138609)

[Benjamin Maxwell via llvm-commits]

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@@ -6057,24 +6067,24 @@ void llvm::emitFrameOffset(MachineBasicBlock &MBB,
 
   assert(!(SetNZCV && (NumPredicateVectors || NumDataVectors)) &&
          "SetNZCV not supported with SVE vectors");
-  assert(!(NeedsWinCFI && (NumPredicateVectors || NumDataVectors)) &&
-         "WinCFI not supported with SVE vectors");
+  assert(!(NeedsWinCFI && NumPredicateVectors) &&
+         "WinCFI can't allocate fractions of an SVE data vector");
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MacDue wrote:

The SVE stack size is always rounded up to a 16-byte multiple (implicitly multiple by vscale), so we always allocate some number of full SVE vectors (which also ensures the stack stays 16-byte aligned). I don't think predicate-sized allocations can occur in frame lowering. 

https://github.com/llvm/llvm-project/pull/138609