1 files changed, 258 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/MachineFrameInfo.cpp b/llvm/lib/CodeGen/MachineFrameInfo.cpp
new file mode 100644
index 000000000000..604f5145b1a0
--- /dev/null
+++ b/llvm/lib/CodeGen/MachineFrameInfo.cpp
@@ -0,0 +1,258 @@
+//===-- 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 " << Alignment.value()
+                    << " exceeds the stack alignment " << StackAlignment.value()
+                    << " 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::None() : 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::None() : 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;
+}
+
+unsigned MachineFrameInfo::estimateStackSize(const MachineFunction &MF) const {
+  const TargetFrameLowering *TFI = MF.getSubtarget().getFrameLowering();
+  const TargetRegisterInfo *RegInfo = MF.getSubtarget().getRegisterInfo();
+  unsigned MaxAlign = getMaxAlignment();
+  int 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;
+    int 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);
+    unsigned Align = getObjectAlignment(i);
+    // Adjust to alignment boundary
+    Offset = (Offset+Align-1)/Align*Align;
+
+    MaxAlign = std::max(Align, 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.
+  unsigned StackAlign;
+  if (adjustsStack() || hasVarSizedObjects() ||
+      (RegInfo->needsStackRealignment(MF) && getObjectIndexEnd() != 0))
+    StackAlign = TFI->getStackAlignment();
+  else
+    StackAlign = TFI->getTransientStackAlignment();
+
+  // 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);
+  unsigned AlignMask = StackAlign - 1;
+  Offset = (Offset + AlignMask) & ~uint64_t(AlignMask);
+
+  return (unsigned)Offset;
+}
+
+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