[llvm] [LiveIntervals] Ignore artificial regs when adding kill flags (PR #116963)

[Jay Foad via llvm-commits]

================
@@ -710,6 +710,30 @@ void LiveIntervals::pruneValue(LiveRange &LR, SlotIndex Kill,
 // Register allocator hooks.
 //
 
+/// Returns true if the physreg has multiple regunits that can be accessed
+/// as independent registers.
+///
+/// Returns 'true' for e.g.:
+///   gpr64_0_gpr64_1
+//               => two independently accessible registers gpr64_0 and gpr64_1.
+///
+/// Returns 'false' for e.g.:
+///   gpr64_0:   => accessible register, reads/writes 64bits
+///   gpr32_0:   => accessible sub-regsiter of gpr64_0, reads/writes 32bits
+//    gpr32_0_hi => top 32bits of gpr64_0, not independently accessible.
+static bool hasMultipleAddressableRegUnits(const TargetRegisterInfo *TRI,
----------------
jayfoad wrote:

This seems like something that could be precomputed by tablegen like isInAllocatableClass, so we would have a simple table lookup instead of all these loops.

https://github.com/llvm/llvm-project/pull/116963