lib/CodeGen/AllocationOrder.cpp

   1 //===-- llvm/CodeGen/AllocationOrder.cpp - Allocation Order ---------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file implements an allocation order for virtual registers.
  11 //
  12 // The preferred allocation order for a virtual register depends on allocation
  13 // hints and target hooks. The AllocationOrder class encapsulates all of that.
  14 //
  15 //===----------------------------------------------------------------------===//
  16
  17 #include "AllocationOrder.h"
  18 #include "llvm/CodeGen/MachineFunction.h"
  19 #include "llvm/CodeGen/MachineRegisterInfo.h"
  20 #include "llvm/CodeGen/RegisterClassInfo.h"
  21 #include "llvm/CodeGen/VirtRegMap.h"
  22 #include "llvm/Support/Debug.h"
  23 #include "llvm/Support/raw_ostream.h"
  24
  25 using namespace llvm;
  26
  27 #define DEBUG_TYPE "regalloc"
  28
  29 // Compare VirtRegMap::getRegAllocPref().
  30 AllocationOrder::AllocationOrder(unsigned VirtReg,
  31                                  const VirtRegMap &VRM,
  32                                  const RegisterClassInfo &RegClassInfo,
  33                                  const LiveRegMatrix *Matrix)
  34   : Pos(0), HardHints(false) {
  35   const MachineFunction &MF = VRM.getMachineFunction();
  36   const TargetRegisterInfo *TRI = &VRM.getTargetRegInfo();
  37   Order = RegClassInfo.getOrder(MF.getRegInfo().getRegClass(VirtReg));
  38   if (TRI->getRegAllocationHints(VirtReg, Order, Hints, MF, &VRM, Matrix))
  39     HardHints = true;
  40   rewind();
  41
  42   LLVM_DEBUG({
  43     if (!Hints.empty()) {
  44       dbgs() << "hints:";
  45       for (unsigned I = 0, E = Hints.size(); I != E; ++I)
  46         dbgs() << ' ' << printReg(Hints[I], TRI);
  47       dbgs() << '\n';
  48     }
  49   });
  50 #ifndef NDEBUG
  51   for (unsigned I = 0, E = Hints.size(); I != E; ++I)
  52     assert(is_contained(Order, Hints[I]) &&
  53            "Target hint is outside allocation order.");
  54 #endif
  55 }