[llvm] [CodeLayout] CDSortImpl: remove linear-time erase_value from mergeChains (PR #69276)

[via llvm-commits]

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@@ -1027,7 +1027,7 @@ class CDSortImpl {
 
     LLVM_DEBUG(dbgs() << "Cache-directed function sorting reduced the number"
                       << " of chains from " << NumNodes << " to "
-                      << HotChains.size() << "\n");
+                      << NumHotChains << "\n");
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spupyrev wrote:

One can move the debug statement to `concatChains()` where we have access to the number of remaining chains, `SortedChains.size()`. So this variable, NumHotChains, won't be needed

https://github.com/llvm/llvm-project/pull/69276