[llvm] [SHT_LLVM_FUNC_MAP][ObjectYaml]Introduce function address map section and emit dynamic instruction count(ObjectYaml part) (PR #124332)

[James Henderson via llvm-commits]

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@@ -535,6 +535,27 @@ Example of BBAddrMap with PGO data:
    .uleb128  1000                         # BB_3 basic block frequency (only when enabled)
    .uleb128  0                            # BB_3 successors count (only enabled with branch probabilities)
 
+``SHT_LLVM_FUNC_MAP`` Section (function address map)
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+This section stores the mapping from the binary address of function to its
+related metadata features. It is used to emit function-level analysis data and
+can be enabled through ``--func-map`` option. The fields are encoded in the
+following format:
+
+#. A version number byte used for backward compatibility.
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jh7370 wrote:

No, it's the same approach as taken by many DWARF sections. Pull the common stuff into a table header and then put the data in the table body, with a size in the header to indicate how much data there is (an alternative approach would be some kind of end marker in the data, but that has issues under some conditions, depending on the values used).

https://github.com/llvm/llvm-project/pull/124332