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[mlir] Add SelectPass #130409

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8 changes: 8 additions & 0 deletions mlir/include/mlir/Transforms/Passes.h
Original file line number Diff line number Diff line change
Expand Up @@ -46,6 +46,7 @@ class GreedyRewriteConfig;
#define GEN_PASS_DECL_SYMBOLPRIVATIZE
#define GEN_PASS_DECL_TOPOLOGICALSORT
#define GEN_PASS_DECL_COMPOSITEFIXEDPOINTPASS
#define GEN_PASS_DECL_SELECTPASS
#include "mlir/Transforms/Passes.h.inc"

/// Creates an instance of the Canonicalizer pass, configured with default
Expand Down Expand Up @@ -139,6 +140,13 @@ std::unique_ptr<Pass> createCompositeFixedPointPass(
std::string name, llvm::function_ref<void(OpPassManager &)> populateFunc,
int maxIterations = 10);

/// Creates select pass which allows to run multiple different set of passes
/// based on attribute value on some top-level op.
std::unique_ptr<Pass> createSelectPass(
std::string name, std::string selectCondName,
ArrayRef<std::pair<StringRef, std::function<void(OpPassManager &)>>>
populateFuncs);

//===----------------------------------------------------------------------===//
// Registration
//===----------------------------------------------------------------------===//
Expand Down
19 changes: 19 additions & 0 deletions mlir/include/mlir/Transforms/Passes.td
Original file line number Diff line number Diff line change
Expand Up @@ -586,4 +586,23 @@ def CompositeFixedPointPass : Pass<"composite-fixed-point-pass"> {
];
}

def SelectPass : Pass<"select-pass"> {
let summary = "Select pass";
let description = [{
Select pass allows to run multiple different set of passes based on
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Multiple different sets, makes me think of something else than switching on attribute to select pipeline.

Dynamically selects pass pipeline to run based on top level op attribute.

attribute value on some top-level op.
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Would this be on the top level it's run on?

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@Hardcode84 Hardcode84 Mar 8, 2025

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Technically, not necessarily on top-level op, just on the op pass is rooted on, clarified the doc.

}];

let options = [
Option<"name", "name", "std::string", /*default=*/"\"SelectPass\"",
"Select pass display name">,
Option<"selectCondName", "select-cond-name", "std::string", "\"select\"",
"Attribute name used for condition">,
ListOption<"selectValues", "select-values", "std::string",
"Values used to check select condition">,
ListOption<"selectPipelines", "select-pipelines", "std::string",
"Pipelines, assotiated with corresponding select values">,
];
}

#endif // MLIR_TRANSFORMS_PASSES
1 change: 1 addition & 0 deletions mlir/lib/Transforms/CMakeLists.txt
Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,7 @@ add_mlir_library(MLIRTransforms
PrintIR.cpp
RemoveDeadValues.cpp
SCCP.cpp
SelectPass.cpp
SROA.cpp
StripDebugInfo.cpp
SymbolDCE.cpp
Expand Down
132 changes: 132 additions & 0 deletions mlir/lib/Transforms/SelectPass.cpp
Original file line number Diff line number Diff line change
@@ -0,0 +1,132 @@
//===- SelectPass.cpp - Select pass code ----------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// SelectPass allows to run multiple different set of passes based on attribute
// value on some top-level op.
//
//===----------------------------------------------------------------------===//

#include "mlir/Transforms/Passes.h"

#include "mlir/Pass/Pass.h"
#include "mlir/Pass/PassManager.h"

namespace mlir {
#define GEN_PASS_DEF_SELECTPASS
#include "mlir/Transforms/Passes.h.inc"
} // namespace mlir

using namespace mlir;

namespace {
struct SelectPass final : public impl::SelectPassBase<SelectPass> {
using SelectPassBase::SelectPassBase;

SelectPass(
std::string name_, std::string selectCondName_,
ArrayRef<std::pair<StringRef, std::function<void(OpPassManager &)>>>
populateFuncs) {
name = std::move(name_);
selectCondName = std::move(selectCondName_);

SmallVector<std::string> selectVals;
SmallVector<std::string> selectPpls;
selectVals.reserve(populateFuncs.size());
selectPpls.reserve(populateFuncs.size());
selectPassManagers.reserve(populateFuncs.size());
for (auto &&[name, populate] : populateFuncs) {
selectVals.emplace_back(name);

auto &pm = selectPassManagers.emplace_back();
populate(pm);

llvm::raw_string_ostream os(selectPpls.emplace_back());
pm.printAsTextualPipeline(os);
}

selectValues = selectVals;
selectPipelines = selectPpls;
}

LogicalResult initializeOptions(
StringRef options,
function_ref<LogicalResult(const Twine &)> errorHandler) override {
if (failed(SelectPassBase::initializeOptions(options, errorHandler)))
return failure();

if (selectCondName.empty())
return errorHandler("Invalid select-cond-name");
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Is this the only requirement on it? (To be specified)


if (selectValues.size() != selectPipelines.size())
return errorHandler("Values and pipelines size mismatch");

selectPassManagers.resize(selectPipelines.size());

for (auto &&[i, pipeline] : llvm::enumerate(selectPipelines)) {
if (failed(parsePassPipeline(pipeline, selectPassManagers[i])))
return errorHandler("Failed to parse pipeline");
}

return success();
}

LogicalResult initialize(MLIRContext *context) override {
condAttrName = StringAttr::get(context, selectCondName);

selectAttrs.reserve(selectAttrs.size());
for (StringRef value : selectValues)
selectAttrs.emplace_back(StringAttr::get(context, value));

return success();
}

void getDependentDialects(DialectRegistry &registry) const override {
for (const OpPassManager &pipeline : selectPassManagers)
pipeline.getDependentDialects(registry);
}

void runOnOperation() override {
Operation *op = getOperation();
Attribute condAttrValue = op->getAttr(condAttrName);
if (!condAttrValue) {
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OOC, what about introducing a default state, so if none is specified the default is run. So the pass always runs but the attribute is used for refinement. (Could also be a TODO here and follow.up)

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Added a TODO for now

op->emitError("Condition attribute not present: ") << condAttrName;
return signalPassFailure();
}

for (auto &&[value, pm] :
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There are probably few enough instances that a linear search would be appropriate but could be revised if needed.

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Yeah, realistically this pass will only have a few options, so linear search should be fine.

llvm::zip_equal(selectAttrs, selectPassManagers)) {
if (value != condAttrValue)
continue;

if (failed(runPipeline(pm, op)))
return signalPassFailure();

return;
}

op->emitError("Unhandled condition value: ") << condAttrValue;
return signalPassFailure();
}

protected:
StringRef getName() const override { return name; }

private:
StringAttr condAttrName;
SmallVector<Attribute> selectAttrs;
SmallVector<OpPassManager> selectPassManagers;
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It's not clear to me how is this handled with respect to serialization? Can you clarify please.

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selectPipelines contains the textual representation of pipelines and it's serialized. selectPassManagers are just cached pipelines to be used when we actually run the pass.

};
} // namespace

std::unique_ptr<Pass> mlir::createSelectPass(
std::string name, std::string selectCondName,
ArrayRef<std::pair<StringRef, std::function<void(OpPassManager &)>>>
populateFuncs) {
return std::make_unique<SelectPass>(std::move(name),
std::move(selectCondName), populateFuncs);
}
24 changes: 24 additions & 0 deletions mlir/test/Transforms/select-pass.mlir
Original file line number Diff line number Diff line change
@@ -0,0 +1,24 @@
// RUN: mlir-opt %s -pass-pipeline='builtin.module(gpu.module(select-pass{ \
// RUN: name=TestSelectPass \
// RUN: select-cond-name=test.attr \
// RUN: select-values=rocdl,nvvm \
// RUN: select-pipelines=convert-gpu-to-rocdl,convert-gpu-to-nvvm \
// RUN: }))' -split-input-file | FileCheck %s

gpu.module @rocdl_module attributes {test.attr = "rocdl"} {
// CHECK-LABEL: func @foo()
// CHECK: rocdl.workitem.id.x
func.func @foo() -> index {
%0 = gpu.thread_id x
return %0 : index
}
}

gpu.module @nvvm_module attributes {test.attr = "nvvm"} {
// CHECK-LABEL: func @bar()
// CHECK: nvvm.read.ptx.sreg.tid.x
func.func @bar() -> index {
%0 = gpu.thread_id x
return %0 : index
}
}