[llvm] CodeGen: Eliminate dynamic relocations in the register superclass tables. (PR #119122)

[Owen Anderson via llvm-commits]

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@@ -42,11 +42,27 @@ class VirtRegMap;
 class LiveIntervals;
 class LiveInterval;
 
+/// TargetSuperClassIterator enumerates all super-registers of RegClass.
+class TargetSuperClassIterator
+    : public iterator_adaptor_base<TargetSuperClassIterator, const unsigned *> {
+public:
+  /// Constructs an end iterator.
+  TargetSuperClassIterator() = default;
+
+  TargetSuperClassIterator(const unsigned *V) { I = V; }
+
+  const unsigned &operator*() const { return *I; }
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resistor wrote:

That's not an obstacle. The bigger problem is that you need a TargetRegisterInfo to do the mapping from IDs back to TargetRegisterClass's, which we can't easily get from inside the iterator.

https://github.com/llvm/llvm-project/pull/119122