aboutsummaryrefslogtreecommitdiffstats
path: root/contrib/libs/llvm14/lib/CodeGen/MachineFrameInfo.cpp
blob: ca5936a14779731be1bc660c92ddcfa9541be81c (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
//===-- MachineFrameInfo.cpp ---------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
/// \file Implements MachineFrameInfo that manages the stack frame.
//
//===----------------------------------------------------------------------===//

#include "llvm/CodeGen/MachineFrameInfo.h"

#include "llvm/ADT/BitVector.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/TargetFrameLowering.h"
#include "llvm/CodeGen/TargetInstrInfo.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/Config/llvm-config.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include <cassert>

#define DEBUG_TYPE "codegen"

using namespace llvm;

void MachineFrameInfo::ensureMaxAlignment(Align Alignment) {
  if (!StackRealignable)
    assert(Alignment <= StackAlignment &&
           "For targets without stack realignment, Alignment is out of limit!");
  if (MaxAlignment < Alignment)
    MaxAlignment = Alignment;
}

/// Clamp the alignment if requested and emit a warning.
static inline Align clampStackAlignment(bool ShouldClamp, Align Alignment,
                                        Align StackAlignment) {
  if (!ShouldClamp || Alignment <= StackAlignment)
    return Alignment;
  LLVM_DEBUG(dbgs() << "Warning: requested alignment " << DebugStr(Alignment)
                    << " exceeds the stack alignment "
                    << DebugStr(StackAlignment)
                    << " when stack realignment is off" << '\n');
  return StackAlignment;
}

int MachineFrameInfo::CreateStackObject(uint64_t Size, Align Alignment,
                                        bool IsSpillSlot,
                                        const AllocaInst *Alloca,
                                        uint8_t StackID) {
  assert(Size != 0 && "Cannot allocate zero size stack objects!");
  Alignment = clampStackAlignment(!StackRealignable, Alignment, StackAlignment);
  Objects.push_back(StackObject(Size, Alignment, 0, false, IsSpillSlot, Alloca,
                                !IsSpillSlot, StackID));
  int Index = (int)Objects.size() - NumFixedObjects - 1;
  assert(Index >= 0 && "Bad frame index!");
  if (StackID == 0)
    ensureMaxAlignment(Alignment);
  return Index;
}

int MachineFrameInfo::CreateSpillStackObject(uint64_t Size, Align Alignment) {
  Alignment = clampStackAlignment(!StackRealignable, Alignment, StackAlignment);
  CreateStackObject(Size, Alignment, true);
  int Index = (int)Objects.size() - NumFixedObjects - 1;
  ensureMaxAlignment(Alignment);
  return Index;
}

int MachineFrameInfo::CreateVariableSizedObject(Align Alignment,
                                                const AllocaInst *Alloca) {
  HasVarSizedObjects = true;
  Alignment = clampStackAlignment(!StackRealignable, Alignment, StackAlignment);
  Objects.push_back(StackObject(0, Alignment, 0, false, false, Alloca, true));
  ensureMaxAlignment(Alignment);
  return (int)Objects.size()-NumFixedObjects-1;
}

int MachineFrameInfo::CreateFixedObject(uint64_t Size, int64_t SPOffset,
                                        bool IsImmutable, bool IsAliased) {
  assert(Size != 0 && "Cannot allocate zero size fixed stack objects!");
  // The alignment of the frame index can be determined from its offset from
  // the incoming frame position.  If the frame object is at offset 32 and
  // the stack is guaranteed to be 16-byte aligned, then we know that the
  // object is 16-byte aligned. Note that unlike the non-fixed case, if the
  // stack needs realignment, we can't assume that the stack will in fact be
  // aligned.
  Align Alignment =
      commonAlignment(ForcedRealign ? Align(1) : StackAlignment, SPOffset);
  Alignment = clampStackAlignment(!StackRealignable, Alignment, StackAlignment);
  Objects.insert(Objects.begin(),
                 StackObject(Size, Alignment, SPOffset, IsImmutable,
                             /*IsSpillSlot=*/false, /*Alloca=*/nullptr,
                             IsAliased));
  return -++NumFixedObjects;
}

int MachineFrameInfo::CreateFixedSpillStackObject(uint64_t Size,
                                                  int64_t SPOffset,
                                                  bool IsImmutable) {
  Align Alignment =
      commonAlignment(ForcedRealign ? Align(1) : StackAlignment, SPOffset);
  Alignment = clampStackAlignment(!StackRealignable, Alignment, StackAlignment);
  Objects.insert(Objects.begin(),
                 StackObject(Size, Alignment, SPOffset, IsImmutable,
                             /*IsSpillSlot=*/true, /*Alloca=*/nullptr,
                             /*IsAliased=*/false));
  return -++NumFixedObjects;
}

BitVector MachineFrameInfo::getPristineRegs(const MachineFunction &MF) const {
  const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
  BitVector BV(TRI->getNumRegs());

  // Before CSI is calculated, no registers are considered pristine. They can be
  // freely used and PEI will make sure they are saved.
  if (!isCalleeSavedInfoValid())
    return BV;

  const MachineRegisterInfo &MRI = MF.getRegInfo();
  for (const MCPhysReg *CSR = MRI.getCalleeSavedRegs(); CSR && *CSR;
       ++CSR)
    BV.set(*CSR);

  // Saved CSRs are not pristine.
  for (auto &I : getCalleeSavedInfo())
    for (MCSubRegIterator S(I.getReg(), TRI, true); S.isValid(); ++S)
      BV.reset(*S);

  return BV;
}

uint64_t MachineFrameInfo::estimateStackSize(const MachineFunction &MF) const {
  const TargetFrameLowering *TFI = MF.getSubtarget().getFrameLowering();
  const TargetRegisterInfo *RegInfo = MF.getSubtarget().getRegisterInfo();
  Align MaxAlign = getMaxAlign();
  int64_t Offset = 0;

  // This code is very, very similar to PEI::calculateFrameObjectOffsets().
  // It really should be refactored to share code. Until then, changes
  // should keep in mind that there's tight coupling between the two.

  for (int i = getObjectIndexBegin(); i != 0; ++i) {
    // Only estimate stack size of default stack.
    if (getStackID(i) != TargetStackID::Default)
      continue;
    int64_t FixedOff = -getObjectOffset(i);
    if (FixedOff > Offset) Offset = FixedOff;
  }
  for (unsigned i = 0, e = getObjectIndexEnd(); i != e; ++i) {
    // Only estimate stack size of live objects on default stack.
    if (isDeadObjectIndex(i) || getStackID(i) != TargetStackID::Default)
      continue;
    Offset += getObjectSize(i);
    Align Alignment = getObjectAlign(i);
    // Adjust to alignment boundary
    Offset = alignTo(Offset, Alignment);

    MaxAlign = std::max(Alignment, MaxAlign);
  }

  if (adjustsStack() && TFI->hasReservedCallFrame(MF))
    Offset += getMaxCallFrameSize();

  // Round up the size to a multiple of the alignment.  If the function has
  // any calls or alloca's, align to the target's StackAlignment value to
  // ensure that the callee's frame or the alloca data is suitably aligned;
  // otherwise, for leaf functions, align to the TransientStackAlignment
  // value.
  Align StackAlign;
  if (adjustsStack() || hasVarSizedObjects() ||
      (RegInfo->hasStackRealignment(MF) && getObjectIndexEnd() != 0))
    StackAlign = TFI->getStackAlign();
  else
    StackAlign = TFI->getTransientStackAlign();

  // If the frame pointer is eliminated, all frame offsets will be relative to
  // SP not FP. Align to MaxAlign so this works.
  StackAlign = std::max(StackAlign, MaxAlign);
  return alignTo(Offset, StackAlign);
}

void MachineFrameInfo::computeMaxCallFrameSize(const MachineFunction &MF) {
  const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo();
  unsigned FrameSetupOpcode = TII.getCallFrameSetupOpcode();
  unsigned FrameDestroyOpcode = TII.getCallFrameDestroyOpcode();
  assert(FrameSetupOpcode != ~0u && FrameDestroyOpcode != ~0u &&
         "Can only compute MaxCallFrameSize if Setup/Destroy opcode are known");

  MaxCallFrameSize = 0;
  for (const MachineBasicBlock &MBB : MF) {
    for (const MachineInstr &MI : MBB) {
      unsigned Opcode = MI.getOpcode();
      if (Opcode == FrameSetupOpcode || Opcode == FrameDestroyOpcode) {
        unsigned Size = TII.getFrameSize(MI);
        MaxCallFrameSize = std::max(MaxCallFrameSize, Size);
        AdjustsStack = true;
      } else if (MI.isInlineAsm()) {
        // Some inline asm's need a stack frame, as indicated by operand 1.
        unsigned ExtraInfo = MI.getOperand(InlineAsm::MIOp_ExtraInfo).getImm();
        if (ExtraInfo & InlineAsm::Extra_IsAlignStack)
          AdjustsStack = true;
      }
    }
  }
}

void MachineFrameInfo::print(const MachineFunction &MF, raw_ostream &OS) const{
  if (Objects.empty()) return;

  const TargetFrameLowering *FI = MF.getSubtarget().getFrameLowering();
  int ValOffset = (FI ? FI->getOffsetOfLocalArea() : 0);

  OS << "Frame Objects:\n";

  for (unsigned i = 0, e = Objects.size(); i != e; ++i) {
    const StackObject &SO = Objects[i];
    OS << "  fi#" << (int)(i-NumFixedObjects) << ": ";

    if (SO.StackID != 0)
      OS << "id=" << static_cast<unsigned>(SO.StackID) << ' ';

    if (SO.Size == ~0ULL) {
      OS << "dead\n";
      continue;
    }
    if (SO.Size == 0)
      OS << "variable sized";
    else
      OS << "size=" << SO.Size;
    OS << ", align=" << SO.Alignment.value();

    if (i < NumFixedObjects)
      OS << ", fixed";
    if (i < NumFixedObjects || SO.SPOffset != -1) {
      int64_t Off = SO.SPOffset - ValOffset;
      OS << ", at location [SP";
      if (Off > 0)
        OS << "+" << Off;
      else if (Off < 0)
        OS << Off;
      OS << "]";
    }
    OS << "\n";
  }
}

#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
LLVM_DUMP_METHOD void MachineFrameInfo::dump(const MachineFunction &MF) const {
  print(MF, dbgs());
}
#endif