llvm/llvm/lib/Transforms/Coroutines/MaterializationUtils.cpp

//===- MaterializationUtils.cpp - Builds and manipulates coroutine frame
//-------------===//
//
// 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 file contains classes used to materialize insts after suspends points.
//===----------------------------------------------------------------------===//

#include "MaterializationUtils.h"
#include "SpillUtils.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/Instruction.h"
#include <deque>

usingnamespacellvm;

usingnamespacecoro;

// The "coro-suspend-crossing" flag is very noisy. There is another debug type,
// "coro-frame", which results in leaner debug spew.
#define DEBUG_TYPE …

namespace {

// RematGraph is used to construct a DAG for rematerializable instructions
// When the constructor is invoked with a candidate instruction (which is
// materializable) it builds a DAG of materializable instructions from that
// point.
// Typically, for each instruction identified as re-materializable across a
// suspend point, a RematGraph will be created.
struct RematGraph { … };

} // namespace

namespace llvm {
template <> struct GraphTraits<RematGraph *> { … };

} // end namespace llvm

// For each instruction identified as materializable across the suspend point,
// and its associated DAG of other rematerializable instructions,
// recreate the DAG of instructions after the suspend point.
static void rewriteMaterializableInstructions(
    const SmallMapVector<Instruction *, std::unique_ptr<RematGraph>, 8>
        &AllRemats) { … }

/// Default materializable callback
// Check for instructions that we can recreate on resume as opposed to spill
// the result into a coroutine frame.
bool llvm::coro::defaultMaterializable(Instruction &V) { … }

bool llvm::coro::isTriviallyMaterializable(Instruction &V) { … }

#ifndef NDEBUG
static void dumpRemats(
    StringRef Title,
    const SmallMapVector<Instruction *, std::unique_ptr<RematGraph>, 8> &RM) {
  dbgs() << "------------- " << Title << "--------------\n";
  for (const auto &E : RM) {
    E.second->dump();
    dbgs() << "--\n";
  }
}
#endif

void coro::doRematerializations(
    Function &F, SuspendCrossingInfo &Checker,
    std::function<bool(Instruction &)> IsMaterializable) { … }