[llvm] [RegAlloc] Add register allocation anti-hints infrastructure (PR #218071)

[Lukas Sommer via llvm-commits]

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@@ -29,6 +30,9 @@ class LiveRegMatrix;
 
 class LLVM_LIBRARY_VISIBILITY AllocationOrder {
   const SmallVector<MCPhysReg, 16> Hints;
+  // Used as storage if the Order received in the constructor needs to be
+  // altered.
+  SmallVector<MCPhysReg, 16> FilteredOrderStorage;
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sommerlukas wrote:

Nit: Do we actually filter registers out or just reorder them? If it's the latter, maybe a different name would be more appropriate.

https://github.com/llvm/llvm-project/pull/218071