lib/CodeGen/AllocationOrder.cpp

   1 //===-- llvm/CodeGen/AllocationOrder.cpp - Allocation Order ---------------===//
   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 implements an allocation order for virtual registers.
  10 //
  11 // The preferred allocation order for a virtual register depends on allocation
  12 // hints and target hooks. The AllocationOrder class encapsulates all of that.
  13 //
  14 //===----------------------------------------------------------------------===//
  15
  16 #include "AllocationOrder.h"
  17 #include "llvm/CodeGen/MachineFunction.h"
  18 #include "llvm/CodeGen/MachineRegisterInfo.h"
  19 #include "llvm/CodeGen/RegisterClassInfo.h"
  20 #include "llvm/CodeGen/VirtRegMap.h"
  21 #include "llvm/Support/Debug.h"
  22 #include "llvm/Support/raw_ostream.h"
  23
  24 using namespace llvm;
  25
  26 #define DEBUG_TYPE "regalloc"
  27
  28 // Compare VirtRegMap::getRegAllocPref().
  29 AllocationOrder::AllocationOrder(unsigned VirtReg,
  30                                  const VirtRegMap &VRM,
  31                                  const RegisterClassInfo &RegClassInfo,
  32                                  const LiveRegMatrix *Matrix)
  33   : Pos(0), HardHints(false) {
  34   const MachineFunction &MF = VRM.getMachineFunction();
  35   const TargetRegisterInfo *TRI = &VRM.getTargetRegInfo();
  36   Order = RegClassInfo.getOrder(MF.getRegInfo().getRegClass(VirtReg));
  37   if (TRI->getRegAllocationHints(VirtReg, Order, Hints, MF, &VRM, Matrix))
  38     HardHints = true;
  39   rewind();
  40
  41   LLVM_DEBUG({
  42     if (!Hints.empty()) {
  43       dbgs() << "hints:";
  44       for (unsigned I = 0, E = Hints.size(); I != E; ++I)
  45         dbgs() << ' ' << printReg(Hints[I], TRI);
  46       dbgs() << '\n';
  47     }
  48   });
  49 #ifndef NDEBUG
  50   for (unsigned I = 0, E = Hints.size(); I != E; ++I)
  51     assert(is_contained(Order, Hints[I]) &&
  52            "Target hint is outside allocation order.");
  53 #endif
  54 }