[llvm] X86: Add prefetch insertion based on Propeller profile (PR #166324)

[Simon Pilgrim via llvm-commits]

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@@ -100,6 +100,12 @@ template <> struct DenseMapInfo<MBBSectionID> {
   }
 };
 
+struct PrefetchTarget {
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RKSimon wrote:

Missing descriptions

https://github.com/llvm/llvm-project/pull/166324