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 //
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