1//===-- HexagonExpandPredSpillCode.cpp - Expand Predicate Spill Code ------===//
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// The Hexagon processor has no instructions that load or store predicate
10// registers directly.  So, when these registers must be spilled a general
11// purpose register must be found and the value copied to/from it from/to
12// the predicate register.  This code currently does not use the register
13// scavenger mechanism available in the allocator.  There are two registers
14// reserved to allow spilling/restoring predicate registers.  One is used to
15// hold the predicate value.  The other is used when stack frame offsets are
16// too large.
17//
18//===----------------------------------------------------------------------===//
19
20#include "HexagonTargetMachine.h"
21#include "HexagonSubtarget.h"
22#include "HexagonMachineFunctionInfo.h"
23#include "llvm/ADT/Statistic.h"
24#include "llvm/CodeGen/LatencyPriorityQueue.h"
25#include "llvm/CodeGen/MachineDominators.h"
26#include "llvm/CodeGen/MachineFunctionPass.h"
27#include "llvm/CodeGen/MachineInstrBuilder.h"
28#include "llvm/CodeGen/MachineLoopInfo.h"
29#include "llvm/CodeGen/MachineRegisterInfo.h"
30#include "llvm/CodeGen/Passes.h"
31#include "llvm/CodeGen/ScheduleHazardRecognizer.h"
32#include "llvm/CodeGen/SchedulerRegistry.h"
33#include "llvm/Target/TargetMachine.h"
34#include "llvm/Target/TargetInstrInfo.h"
35#include "llvm/Target/TargetRegisterInfo.h"
36#include "llvm/Support/Compiler.h"
37#include "llvm/Support/Debug.h"
38#include "llvm/Support/MathExtras.h"
39
40using namespace llvm;
41
42
43namespace {
44
45class HexagonExpandPredSpillCode : public MachineFunctionPass {
46    HexagonTargetMachine& QTM;
47    const HexagonSubtarget &QST;
48
49 public:
50    static char ID;
51    HexagonExpandPredSpillCode(HexagonTargetMachine& TM) :
52      MachineFunctionPass(ID), QTM(TM), QST(*TM.getSubtargetImpl()) {}
53
54    const char *getPassName() const {
55      return "Hexagon Expand Predicate Spill Code";
56    }
57    bool runOnMachineFunction(MachineFunction &Fn);
58};
59
60
61char HexagonExpandPredSpillCode::ID = 0;
62
63
64bool HexagonExpandPredSpillCode::runOnMachineFunction(MachineFunction &Fn) {
65
66  const HexagonInstrInfo *TII = QTM.getInstrInfo();
67
68  // Loop over all of the basic blocks.
69  for (MachineFunction::iterator MBBb = Fn.begin(), MBBe = Fn.end();
70       MBBb != MBBe; ++MBBb) {
71    MachineBasicBlock* MBB = MBBb;
72    // Traverse the basic block.
73    for (MachineBasicBlock::iterator MII = MBB->begin(); MII != MBB->end();
74         ++MII) {
75      MachineInstr *MI = MII;
76      int Opc = MI->getOpcode();
77      if (Opc == Hexagon::STriw_pred) {
78        // STriw_pred [R30], ofst, SrcReg;
79        unsigned FP = MI->getOperand(0).getReg();
80        assert(FP == QTM.getRegisterInfo()->getFrameRegister() &&
81               "Not a Frame Pointer, Nor a Spill Slot");
82        assert(MI->getOperand(1).isImm() && "Not an offset");
83        int Offset = MI->getOperand(1).getImm();
84        int SrcReg = MI->getOperand(2).getReg();
85        assert(Hexagon::PredRegsRegClass.contains(SrcReg) &&
86               "Not a predicate register");
87        if (!TII->isValidOffset(Hexagon::STriw_indexed, Offset)) {
88          if (!TII->isValidOffset(Hexagon::ADD_ri, Offset)) {
89            BuildMI(*MBB, MII, MI->getDebugLoc(),
90                    TII->get(Hexagon::CONST32_Int_Real),
91                      HEXAGON_RESERVED_REG_1).addImm(Offset);
92            BuildMI(*MBB, MII, MI->getDebugLoc(), TII->get(Hexagon::ADD_rr),
93                    HEXAGON_RESERVED_REG_1)
94              .addReg(FP).addReg(HEXAGON_RESERVED_REG_1);
95            BuildMI(*MBB, MII, MI->getDebugLoc(), TII->get(Hexagon::TFR_RsPd),
96                      HEXAGON_RESERVED_REG_2).addReg(SrcReg);
97            BuildMI(*MBB, MII, MI->getDebugLoc(),
98                    TII->get(Hexagon::STriw_indexed))
99              .addReg(HEXAGON_RESERVED_REG_1)
100              .addImm(0).addReg(HEXAGON_RESERVED_REG_2);
101          } else {
102            BuildMI(*MBB, MII, MI->getDebugLoc(), TII->get(Hexagon::ADD_ri),
103                      HEXAGON_RESERVED_REG_1).addReg(FP).addImm(Offset);
104            BuildMI(*MBB, MII, MI->getDebugLoc(), TII->get(Hexagon::TFR_RsPd),
105                      HEXAGON_RESERVED_REG_2).addReg(SrcReg);
106            BuildMI(*MBB, MII, MI->getDebugLoc(),
107                          TII->get(Hexagon::STriw_indexed))
108              .addReg(HEXAGON_RESERVED_REG_1)
109              .addImm(0)
110              .addReg(HEXAGON_RESERVED_REG_2);
111          }
112        } else {
113          BuildMI(*MBB, MII, MI->getDebugLoc(), TII->get(Hexagon::TFR_RsPd),
114                    HEXAGON_RESERVED_REG_2).addReg(SrcReg);
115          BuildMI(*MBB, MII, MI->getDebugLoc(),
116                        TII->get(Hexagon::STriw_indexed)).
117                    addReg(FP).addImm(Offset).addReg(HEXAGON_RESERVED_REG_2);
118        }
119        MII = MBB->erase(MI);
120        --MII;
121      } else if (Opc == Hexagon::LDriw_pred) {
122        // DstReg = LDriw_pred [R30], ofst.
123        int DstReg = MI->getOperand(0).getReg();
124        assert(Hexagon::PredRegsRegClass.contains(DstReg) &&
125               "Not a predicate register");
126        unsigned FP = MI->getOperand(1).getReg();
127        assert(FP == QTM.getRegisterInfo()->getFrameRegister() &&
128               "Not a Frame Pointer, Nor a Spill Slot");
129        assert(MI->getOperand(2).isImm() && "Not an offset");
130        int Offset = MI->getOperand(2).getImm();
131        if (!TII->isValidOffset(Hexagon::LDriw, Offset)) {
132          if (!TII->isValidOffset(Hexagon::ADD_ri, Offset)) {
133            BuildMI(*MBB, MII, MI->getDebugLoc(),
134                    TII->get(Hexagon::CONST32_Int_Real),
135                      HEXAGON_RESERVED_REG_1).addImm(Offset);
136            BuildMI(*MBB, MII, MI->getDebugLoc(), TII->get(Hexagon::ADD_rr),
137                    HEXAGON_RESERVED_REG_1)
138              .addReg(FP)
139              .addReg(HEXAGON_RESERVED_REG_1);
140            BuildMI(*MBB, MII, MI->getDebugLoc(), TII->get(Hexagon::LDriw),
141                      HEXAGON_RESERVED_REG_2)
142              .addReg(HEXAGON_RESERVED_REG_1)
143              .addImm(0);
144            BuildMI(*MBB, MII, MI->getDebugLoc(), TII->get(Hexagon::TFR_PdRs),
145                      DstReg).addReg(HEXAGON_RESERVED_REG_2);
146          } else {
147            BuildMI(*MBB, MII, MI->getDebugLoc(), TII->get(Hexagon::ADD_ri),
148                      HEXAGON_RESERVED_REG_1).addReg(FP).addImm(Offset);
149            BuildMI(*MBB, MII, MI->getDebugLoc(), TII->get(Hexagon::LDriw),
150                      HEXAGON_RESERVED_REG_2)
151              .addReg(HEXAGON_RESERVED_REG_1)
152              .addImm(0);
153            BuildMI(*MBB, MII, MI->getDebugLoc(), TII->get(Hexagon::TFR_PdRs),
154                      DstReg).addReg(HEXAGON_RESERVED_REG_2);
155          }
156        } else {
157          BuildMI(*MBB, MII, MI->getDebugLoc(), TII->get(Hexagon::LDriw),
158                    HEXAGON_RESERVED_REG_2).addReg(FP).addImm(Offset);
159          BuildMI(*MBB, MII, MI->getDebugLoc(), TII->get(Hexagon::TFR_PdRs),
160                    DstReg).addReg(HEXAGON_RESERVED_REG_2);
161        }
162        MII = MBB->erase(MI);
163        --MII;
164      }
165    }
166  }
167
168  return true;
169}
170
171}
172
173//===----------------------------------------------------------------------===//
174//                         Public Constructor Functions
175//===----------------------------------------------------------------------===//
176
177FunctionPass *llvm::createHexagonExpandPredSpillCode(HexagonTargetMachine &TM) {
178  return new HexagonExpandPredSpillCode(TM);
179}
180