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      1 //===-- LiveRangeUtils.h - Live Range modification utilities ----*- C++ -*-===//
      2 //
      3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
      4 // See https://llvm.org/LICENSE.txt for license information.
      5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
      6 //
      7 //===----------------------------------------------------------------------===//
      8 /// \file
      9 /// This file contains helper functions to modify live ranges.
     10 ///
     11 //===----------------------------------------------------------------------===//
     12 
     13 #ifndef LLVM_LIB_CODEGEN_LIVERANGEUTILS_H
     14 #define LLVM_LIB_CODEGEN_LIVERANGEUTILS_H
     15 
     16 #include "llvm/CodeGen/LiveInterval.h"
     17 
     18 namespace llvm {
     19 
     20 /// Helper function that distributes live range value numbers and the
     21 /// corresponding segments of a master live range \p LR to a list of newly
     22 /// created live ranges \p SplitLRs. \p VNIClasses maps each value number in \p
     23 /// LR to 0 meaning it should stay or to 1..N meaning it should go to a specific
     24 /// live range in the \p SplitLRs array.
     25 template<typename LiveRangeT, typename EqClassesT>
     26 static void DistributeRange(LiveRangeT &LR, LiveRangeT *SplitLRs[],
     27                             EqClassesT VNIClasses) {
     28   // Move segments to new intervals.
     29   typename LiveRangeT::iterator J = LR.begin(), E = LR.end();
     30   while (J != E && VNIClasses[J->valno->id] == 0)
     31     ++J;
     32   for (typename LiveRangeT::iterator I = J; I != E; ++I) {
     33     if (unsigned eq = VNIClasses[I->valno->id]) {
     34       assert((SplitLRs[eq-1]->empty() || SplitLRs[eq-1]->expiredAt(I->start)) &&
     35              "New intervals should be empty");
     36       SplitLRs[eq-1]->segments.push_back(*I);
     37     } else
     38       *J++ = *I;
     39   }
     40   LR.segments.erase(J, E);
     41 
     42   // Transfer VNInfos to their new owners and renumber them.
     43   unsigned j = 0, e = LR.getNumValNums();
     44   while (j != e && VNIClasses[j] == 0)
     45     ++j;
     46   for (unsigned i = j; i != e; ++i) {
     47     VNInfo *VNI = LR.getValNumInfo(i);
     48     if (unsigned eq = VNIClasses[i]) {
     49       VNI->id = SplitLRs[eq-1]->getNumValNums();
     50       SplitLRs[eq-1]->valnos.push_back(VNI);
     51     } else {
     52       VNI->id = j;
     53       LR.valnos[j++] = VNI;
     54     }
     55   }
     56   LR.valnos.resize(j);
     57 }
     58 
     59 } // End llvm namespace
     60 
     61 #endif
     62