## Motivation
Some architectures can facilitate the LLVM backend with `tensorize` to do code generation, but would require some extra operations before or after the generated loop program to ensure result correctness. An example of this would be the [Gemmini](https://github.com/ucb-bar/gemmini) matrix multiplication accelerator, whose execution flow can be embedded into normal LLVM code generation for RISC-V, but requires explicit `fence` instructions to block the execution flow until data has been fully flushed back to DRAM. It would be helpful to be able to insert `void(void)` function calls before and after the generated nested loop program. The calling pair should be able to surround any level of the nested loop program for fine-grain control. ## Proposed change A pair of pragmas, `prologue` and `epilogue`, are proposed to support the pattern. The use case would be like the following: ```python s[C].pragma(yo, "prologue", "test_prologue") s[C].pragma(yo, "epilogue", "test_epilogue") ``` with corresponding C code ```cpp extern "C" int test_prologue() { printf("%s invoked\n", __func__); return 0; } extern "C" int test_epilogue() { printf("%s invoked\n", __func__); return 0; } ``` A more complete example can be found in [this gist](https://gist.github.com/KireinaHoro/c959170557d75d81c52c116c3750d78a). A quick implementation would be https://github.com/apache/incubator-tvm/pull/5050, to directly emit call nodes when doing LLVM codegen if the pragma is detected. ## Discussion - Is the form of `pragma` suitable for expressing this kind of operation? - Are the names `prologue` and `epilogue` expressive? - The call nodes are directly emitted in LLVM codegen backend in the pull request. Is this the correct / preferred way to do this? --- [Visit Topic](https://discuss.tvm.ai/t/add-support-for-extern-prologue-epilogue-functions/6041/1) to respond. You are receiving this because you enabled mailing list mode. To unsubscribe from these emails, [click here](https://discuss.tvm.ai/email/unsubscribe/37a4ffd23263fdc58f19ee6da326e55e63808cd84463341c43dc4839ccc2ea48).
