llvm/llvm/include/llvm/Transforms/IPO/IROutliner.h

//===- IROutliner.h - Extract similar IR regions into functions --*- 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
//
//===----------------------------------------------------------------------===//
//
// \file
// The interface file for the IROutliner which is used by the IROutliner Pass.
//
// The outliner uses the IRSimilarityIdentifier to identify the similar regions
// of code.  It evaluates each set of IRSimilarityCandidates with an estimate of
// whether it will provide code size reduction.  Each region is extracted using
// the code extractor.  These extracted functions are consolidated into a single
// function and called from the extracted call site.
//
// For example:
// \code
//   %1 = add i32 %a, %b
//   %2 = add i32 %b, %a
//   %3 = add i32 %b, %a
//   %4 = add i32 %a, %b
// \endcode
// would become function
// \code
// define internal void outlined_ir_function(i32 %0, i32 %1) {
//   %1 = add i32 %0, %1
//   %2 = add i32 %1, %0
//   ret void
// }
// \endcode
// with calls:
// \code
//   call void outlined_ir_function(i32 %a, i32 %b)
//   call void outlined_ir_function(i32 %b, i32 %a)
// \endcode
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_TRANSFORMS_IPO_IROUTLINER_H
#define LLVM_TRANSFORMS_IPO_IROUTLINER_H

#include "llvm/Analysis/IRSimilarityIdentifier.h"
#include "llvm/IR/PassManager.h"
#include "llvm/Support/InstructionCost.h"
#include "llvm/Transforms/Utils/CodeExtractor.h"

struct OutlinableGroup;

namespace llvm {
usingnamespaceCallingConv;
usingnamespaceIRSimilarity;

class Module;
class TargetTransformInfo;
class OptimizationRemarkEmitter;

/// The OutlinableRegion holds all the information for a specific region, or
/// sequence of instructions. This includes what values need to be hoisted to
/// arguments from the extracted function, inputs and outputs to the region, and
/// mapping from the extracted function arguments to overall function arguments.
struct OutlinableRegion { … };

/// This class is a pass that identifies similarity in a Module, extracts
/// instances of the similarity, and then consolidating the similar regions
/// in an effort to reduce code size.  It uses the IRSimilarityIdentifier pass
/// to identify the similar regions of code, and then extracts the similar
/// sections into a single function.  See the above for an example as to
/// how code is extracted and consolidated into a single function.
class IROutliner { … };

/// Pass to outline similar regions.
class IROutlinerPass : public PassInfoMixin<IROutlinerPass> { … };

} // end namespace llvm

#endif // LLVM_TRANSFORMS_IPO_IROUTLINER_H