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# .callgraph Section Layout
The `.callgraph` section is used to store call graph information for each function. The section contains a series of records, with each record corresponding to a single function.
## Per Function Record Layout
Each record in the `.callgraph` section has the following binary layout:
| Field | Type | Size (bits) | Description |
| -------------------------------------- | ------------- | ----------- | ------------------------------------------------------------------------------------------------------- |
| Format Version | `uint8_t` | 8 | The version of the record format. The current version is 0. |
| Flags | `uint8_t` | 8 | A bitfield where: Bit 0 is set if the function is a potential indirect call target; Bit 1 is set if there are direct callees; Bit 2 is set if there are indirect callees. The remaining 5 bits are reserved. |
| Function Entry PC | `uintptr_t` | 32/64 | The address of the function's entry point. |
| Function Type ID | `uint64_t` | 64 | The type ID of the function. This field is non-zero if the function is a potential indirect call target and its type is known. |
| Number of Unique Direct Callees | `ULEB128` | Variable | The number of unique direct call destinations from this function. This field is only present if there is at least one direct callee. |
| Direct Callees Array | `uintptr_t[]` | Variable | An array of unique direct callee entry point addresses. This field is only present if there is at least one direct callee. |
| Number of Unique Indirect Target Type IDs| `ULEB128` | Variable | The number of unique indirect call target type IDs. This field is only present if there is at least one indirect target type ID. |
| Indirect Target Type IDs Array | `uint64_t[]` | Variable | An array of unique indirect call target type IDs. This field is only present if there is at least one indirect target type ID. |
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