llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT--> @llvm/pr-subscribers-mlir Author: Jeff Niu (Mogball) <details> <summary>Changes</summary> Stacked PRs: * __->__#<!-- -->89664 * #<!-- -->89628 * #<!-- -->89423 * #<!-- -->89424 --- --- --- ### [mlir][ods] Add documentation on how to use sharded op definitions (NFC) This adds explanations and instructions on how to set up a dialect for sharded op definitions to the MLIR documentation. --- Full diff: https://github.com/llvm/llvm-project/pull/89664.diff 1 Files Affected: - (modified) mlir/docs/DefiningDialects/Operations.md (+94) ``````````diff diff --git a/mlir/docs/DefiningDialects/Operations.md b/mlir/docs/DefiningDialects/Operations.md index 729393d5362673..79a0cc55f13840 100644 --- a/mlir/docs/DefiningDialects/Operations.md +++ b/mlir/docs/DefiningDialects/Operations.md @@ -1114,6 +1114,100 @@ void process(AddOp op, ArrayRef<Value> newOperands) { } ``` +#### Sharded Operation Definitions + +Large dialects with many operations may struggle with C++ compile time of +generated op definitions, due to large compilation units. `mlir-tblgen` +provides the ability to shard op definitions by splitting them up evenly +by passing `-op-shard-count` to `-gen-op-defs` and `-gen-op-decls`. The tool +will generate a single include file for the definitions broken up by +`GET_OP_DEFS_${N}` where `${N}` is the shard number. A shard can be compiled in +a single compilation unit by adding a file like this to your dialect library: + +```c++ +#include "mlir/IR/Operation.h" +// Add any other required includes. + +// Utilities shared by generated op definitions: custom directive parsers, +// printers, etc. +#include "OpUtils.h" + +#define GET_OP_DEFS_0 +#include "MyDialectOps.cpp.inc" +``` + +Note: this requires restructing shared utility functions within the dialect +library so they can be shared by multiple compilation units. I.e. instead of +defining `static` methods in the same source file, you should declare them in a +shared header and define them in their own source file. + +The op registration hooks are also sharded, because the template instantiation +can take a very long time to compile. Operations should be registered in your +dialect like: + +```c++ +void MyDialect::initialize() { + registerMyDialectOperations(this); +} +``` + +CMake and Bazel functions are included to make sharding dialects easier. +Assuming you have organized your operation utility functions into their own +header, define a file that looks like the one above, but without the `#define`: + +```c++ +// MyDialectOps.cpp +#include "mlir/IR/Operation.h" + +#include "OpUtils.h" + +#include "MyDialectOps.cpp.inc" +``` + +In CMake, remove the manual `mlir_tablegen` invocations and replace them with: + +```cmake +set(LLVM_TARGET_DEFINITIONS MyDialectOps.td) +add_sharded_ops(MyDialectOps 8) # shard the op definitions by 8 + +add_mlir_library(MyDialect + MyDialect.cpp + MyDialectOpDefs.cpp + ${SHARDED_SRCS} + + DEPENDS + MLIRTestOpsShardGen +) +``` + +This will automatically duplicate the `MyDialectOps.cpp` source file and add the +`#define` up the number of shards indicated. + +It is recommended that any out-of-line op member functions (like verifiers) be +defined in a separate source file. In this example, it is called +`MyDialectOpDefs.cpp`. + +In Bazel, remove the `-gen-op-defs` and `-gen-op-decls` invocations, and add + +```bazel +gentbl_sharded_ops( + name = "MyDialectOpSrcs", + hdr_out = "MyDialectOps.h.inc", + shard_count = 8, + sharder = "//mlir:mlir-src-sharder", + src_file = "MyDialectOps.cpp", + src_out = "MyDialectOps.cpp.inc", + tblgen = "//mlir:mlir-tblgen", + td_file = "MyDialectOps.td", + deps = [":MyDialectOpsTdFiles"], +) + +cc_library( + name = "MyDialect", + srcs = glob(["MyDialect/*.cpp"]) + [":MyDialectOpSrcs"] +) +``` + ## Constraints Constraint is a core concept in table-driven operation definition: operation `````````` </details> https://github.com/llvm/llvm-project/pull/89664 _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
