[llvm] [BasicBlockSections] Introduce the path cloning profile format to BasicBlockSectionsProfileReader. (PR #67214)

[David Li via llvm-commits]

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@@ -61,8 +81,24 @@ BasicBlockSectionsProfileReader::getBBClusterInfoForFunction(
 // aliases. Basic block clusters are specified by 'c' and specify the cluster of
 // basic blocks, and the internal order in which they must be placed in the same
 // section.
+// This profile can also specify cloning paths which instruct the compiler to
+// clone basic blocks along a path. The cloned blocks are then specified in the
+// cluster information.
+// The following profile lists two cloning paths (starting with 'p') for
+// function bar and places the total 11 blocks within two clusters. Each cloned
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david-xl wrote:

Perhaps add a ascii art of the CFG before and after cloning with the labels to illustrate the the prefix/cluster format?

https://github.com/llvm/llvm-project/pull/67214