[llvm] [AMDGPU] Filter candidates of LiveRegOptimizer for profitable cases (PR #124624)

[Jeffrey Byrnes via llvm-commits]

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@@ -125,6 +127,131 @@ class LiveRegOptimizer {
     return LK.first != TargetLoweringBase::TypeLegal;
   }
 
+  /// Check if intrinsic natively operates on 8-bit or 16-bit
+  bool isNativeIntrinsic(Intrinsic::ID ID) {
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jrbyrnes wrote:

> Is any target intrinsic good enough

It's probably "good enough" -- it may result in false positive (i.e. applying the coercion to cases where the is no profit), but maybe not many.
a
What we really want is a way to check if an intrinsic / instruction can natively handle illegal vector types without compiler assistance to scalarize the code -- this query may be useful for future work too.

https://github.com/llvm/llvm-project/pull/124624