[llvm] [SLP]Improved reduction cost/codegen (PR #118293)

[Simon Pilgrim via llvm-commits]

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@@ -1611,6 +1611,10 @@ class TargetTransformInfo {
   /// split during legalization. Zero is returned when the answer is unknown.
   unsigned getNumberOfParts(Type *Tp) const;
 
+  /// \return true if \p Tp represent a type, fully occupying whole register,
+  /// false otherwise.
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RKSimon wrote:

Improve the description as it doesn't seem to match the implementation in BasicTTIImpl.h

https://github.com/llvm/llvm-project/pull/118293