torch-mlir/lib/RefBackend/TensorToMemref/LowerConstantTensorsToMemre...

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C++

//===----------------------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "../PassDetail.h"
#include "npcomp/RefBackend/RefBackend.h"
#include "mlir/Dialect/Linalg/IR/LinalgOps.h"
#include "mlir/Dialect/Linalg/IR/LinalgTypes.h"
#include "mlir/Dialect/SCF/SCF.h"
#include "mlir/Dialect/Shape/IR/Shape.h"
#include "mlir/Dialect/StandardOps/IR/Ops.h"
#include "mlir/Pass/Pass.h"
#include "mlir/Pass/PassRegistry.h"
#include "mlir/Transforms/DialectConversion.h"
#include "npcomp/Dialect/Refback/IR/RefbackDialect.h"
#include "npcomp/Dialect/Refback/IR/RefbackOps.h"
using namespace mlir;
using namespace mlir::NPCOMP;
//===----------------------------------------------------------------------===//
// LowerConstantTensorsToMemref
//===----------------------------------------------------------------------===//
namespace {
// This class creates global ops for all tensor-valued constants in the program.
// It creates them with pretty names and makes sure that duplicate globals
// aren't created.
class GlobalCreator {
public:
explicit GlobalCreator(ModuleOp module);
refback::GlobalOp getGlobalFor(Attribute attr) {
assert(globals.find(attr) != globals.end() && "unknown constant attr");
return globals[attr];
}
private:
DenseMap<Attribute, refback::GlobalOp> globals;
};
GlobalCreator::GlobalCreator(ModuleOp module) {
// Create a builder without an insertion point. We will insert using the
// symbol table to guarantee unique names.
OpBuilder globalBuilder(module.getContext());
SymbolTable symbolTable(module);
module.walk([&](ConstantOp op) {
// We only want tensor constants for now.
auto type = op.getType().dyn_cast<RankedTensorType>();
if (!type)
return;
// If we already have a global for this constant value, no need to do
// anything else.
auto it = globals.find(op.getValue());
if (it != globals.end())
return;
// Create a pretty name.
SmallString<64> buf;
llvm::raw_svector_ostream os(buf);
interleave(type.getShape(), os, "x");
os << "x" << type.getElementType();
auto global = globalBuilder.create<refback::GlobalOp>(
op.getLoc(), (Twine("__constant_") + os.str()).str(),
op.getValue().cast<ElementsAttr>());
symbolTable.insert(global);
// The symbol table inserts at the end of the module, but globals are a bit
// nicer if they are at the beginning.
global.getOperation()->moveBefore(&module.front());
globals[op.getValue()] = global;
});
}
} // namespace
namespace {
class LowerConstantTensorsToMemref
: public LowerConstantTensorsToMemrefBase<LowerConstantTensorsToMemref> {
void getDependentDialects(DialectRegistry &registry) const override {
registry.insert<refback::RefbackDialect>();
}
void runOnOperation() override {
auto module = getOperation();
GlobalCreator globals(module);
// With the global traversal factored into GlobalCreator, this could in
// principle be done with a pattern.
module.walk([&](ConstantOp op) {
auto type = op.getType().dyn_cast<RankedTensorType>();
if (!type)
return;
auto global = globals.getGlobalFor(op.getValue());
OpBuilder builder(op);
auto memrefType = MemRefType::get(type.getShape(), type.getElementType());
auto memref = builder.create<refback::GetGlobalMemrefOp>(
op.getLoc(), memrefType, global.getName());
Value tensor = builder.create<TensorLoadOp>(op.getLoc(), type, memref);
op.replaceAllUsesWith(tensor);
op.erase();
});
}
};
} // namespace
std::unique_ptr<OperationPass<ModuleOp>>
mlir::NPCOMP::createLowerConstantTensorsToMemrefPass() {
return std::make_unique<LowerConstantTensorsToMemref>();
}