[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:

> I see. So we will get one section per module with multiple function entries and one header. Then the linker will simply concatenate these sections. So we may end up with multiple headers. Is that right?

Yes, we'd get multiple headers - again, see what happens when you link together two DWARF-containing object files.

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