llvm/mlir/lib/Transforms/SCCP.cpp

//===- SCCP.cpp - Sparse Conditional Constant Propagation -----------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This transformation pass performs a sparse conditional constant propagation
// in MLIR. It identifies values known to be constant, propagates that
// information throughout the IR, and replaces them. This is done with an
// optimistic dataflow analysis that assumes that all values are constant until
// proven otherwise.
//
//===----------------------------------------------------------------------===//

#include "mlir/Transforms/Passes.h"

#include "mlir/Analysis/DataFlow/ConstantPropagationAnalysis.h"
#include "mlir/Analysis/DataFlow/DeadCodeAnalysis.h"
#include "mlir/IR/Builders.h"
#include "mlir/IR/Dialect.h"
#include "mlir/Interfaces/SideEffectInterfaces.h"
#include "mlir/Pass/Pass.h"
#include "mlir/Transforms/FoldUtils.h"

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

usingnamespacemlir;
usingnamespacemlir::dataflow;

//===----------------------------------------------------------------------===//
// SCCP Rewrites
//===----------------------------------------------------------------------===//

/// Replace the given value with a constant if the corresponding lattice
/// represents a constant. Returns success if the value was replaced, failure
/// otherwise.
static LogicalResult replaceWithConstant(DataFlowSolver &solver,
                                         OpBuilder &builder,
                                         OperationFolder &folder, Value value) { … }

/// Rewrite the given regions using the computing analysis. This replaces the
/// uses of all values that have been computed to be constant, and erases as
/// many newly dead operations.
static void rewrite(DataFlowSolver &solver, MLIRContext *context,
                    MutableArrayRef<Region> initialRegions) { … }

//===----------------------------------------------------------------------===//
// SCCP Pass
//===----------------------------------------------------------------------===//

namespace {
struct SCCP : public impl::SCCPBase<SCCP> { … };
} // namespace

void SCCP::runOnOperation() { … }

std::unique_ptr<Pass> mlir::createSCCPPass() { … }