llvm-project/llvm/lib/CodeGen/LiveRangeUtils.h

//===-- LiveRangeUtils.h - Live Range modification utilities ----*- 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
/// This file contains helper functions to modify live ranges.
///
//===----------------------------------------------------------------------===//

#ifndef LLVM_LIB_CODEGEN_LIVERANGEUTILS_H
#define LLVM_LIB_CODEGEN_LIVERANGEUTILS_H

#include "llvm/CodeGen/LiveInterval.h"

namespace llvm {

/// Helper function that distributes live range value numbers and the
/// corresponding segments of a primary live range \p LR to a list of newly
/// created live ranges \p SplitLRs. \p VNIClasses maps each value number in \p
/// LR to 0 meaning it should stay or to 1..N meaning it should go to a specific
/// live range in the \p SplitLRs array.
template<typename LiveRangeT, typename EqClassesT>
static void DistributeRange(LiveRangeT &LR, LiveRangeT *SplitLRs[],
                            EqClassesT VNIClasses) {
  // Move segments to new intervals.
  typename LiveRangeT::iterator J = LR.begin(), E = LR.end();
  while (J != E && VNIClasses[J->valno->id] == 0)
    ++J;
  for (typename LiveRangeT::iterator I = J; I != E; ++I) {
    if (unsigned eq = VNIClasses[I->valno->id]) {
      assert((SplitLRs[eq-1]->empty() || SplitLRs[eq-1]->expiredAt(I->start)) &&
             "New intervals should be empty");
      SplitLRs[eq-1]->segments.push_back(*I);
    } else
      *J++ = *I;
  }
  LR.segments.erase(J, E);

  // Transfer VNInfos to their new owners and renumber them.
  unsigned j = 0, e = LR.getNumValNums();
  while (j != e && VNIClasses[j] == 0)
    ++j;
  for (unsigned i = j; i != e; ++i) {
    VNInfo *VNI = LR.getValNumInfo(i);
    if (unsigned eq = VNIClasses[i]) {
      VNI->id = SplitLRs[eq-1]->getNumValNums();
      SplitLRs[eq-1]->valnos.push_back(VNI);
    } else {
      VNI->id = j;
      LR.valnos[j++] = VNI;
    }
  }
  LR.valnos.resize(j);
}

} // End llvm namespace

#endif