Rename TargetFrameInfo into TargetFrameLowering. Also, put couple of FIXMEs and fixes here and there.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123170 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 386 insertions, 0 deletions

diff --git a/lib/Target/SystemZ/SystemZFrameLowering.cpp b/lib/Target/SystemZ/SystemZFrameLowering.cpp
new file mode 100644
index 0000000000..05c2b89fe4
--- /dev/null
+++ b/lib/Target/SystemZ/SystemZFrameLowering.cpp
@@ -0,0 +1,386 @@
+//=====- SystemZFrameLowering.cpp - SystemZ Frame Information ------*- C++ -*-====//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains the SystemZ implementation of TargetFrameLowering class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "SystemZFrameLowering.h"
+#include "SystemZInstrBuilder.h"
+#include "SystemZInstrInfo.h"
+#include "SystemZMachineFunctionInfo.h"
+#include "llvm/Function.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineModuleInfo.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Target/TargetOptions.h"
+#include "llvm/Support/CommandLine.h"
+
+using namespace llvm;
+
+SystemZFrameLowering::SystemZFrameLowering(const SystemZSubtarget &sti)
+  : TargetFrameLowering(TargetFrameLowering::StackGrowsDown, 8, -160), STI(sti) {
+  // Fill the spill offsets map
+  static const unsigned SpillOffsTab[][2] = {
+    { SystemZ::R2D,  0x10 },
+    { SystemZ::R3D,  0x18 },
+    { SystemZ::R4D,  0x20 },
+    { SystemZ::R5D,  0x28 },
+    { SystemZ::R6D,  0x30 },
+    { SystemZ::R7D,  0x38 },
+    { SystemZ::R8D,  0x40 },
+    { SystemZ::R9D,  0x48 },
+    { SystemZ::R10D, 0x50 },
+    { SystemZ::R11D, 0x58 },
+    { SystemZ::R12D, 0x60 },
+    { SystemZ::R13D, 0x68 },
+    { SystemZ::R14D, 0x70 },
+    { SystemZ::R15D, 0x78 }
+  };
+
+  RegSpillOffsets.grow(SystemZ::NUM_TARGET_REGS);
+
+  for (unsigned i = 0, e = array_lengthof(SpillOffsTab); i != e; ++i)
+    RegSpillOffsets[SpillOffsTab[i][0]] = SpillOffsTab[i][1];
+}
+
+/// needsFP - Return true if the specified function should have a dedicated
+/// frame pointer register.  This is true if the function has variable sized
+/// allocas or if frame pointer elimination is disabled.
+bool SystemZFrameLowering::hasFP(const MachineFunction &MF) const {
+  const MachineFrameInfo *MFI = MF.getFrameInfo();
+  return DisableFramePointerElim(MF) || MFI->hasVarSizedObjects();
+}
+
+/// emitSPUpdate - Emit a series of instructions to increment / decrement the
+/// stack pointer by a constant value.
+static
+void emitSPUpdate(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
+                  int64_t NumBytes, const TargetInstrInfo &TII) {
+  unsigned Opc; uint64_t Chunk;
+  bool isSub = NumBytes < 0;
+  uint64_t Offset = isSub ? -NumBytes : NumBytes;
+
+  if (Offset >= (1LL << 15) - 1) {
+    Opc = SystemZ::ADD64ri32;
+    Chunk = (1LL << 31) - 1;
+  } else {
+    Opc = SystemZ::ADD64ri16;
+    Chunk = (1LL << 15) - 1;
+  }
+
+  DebugLoc DL = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
+
+  while (Offset) {
+    uint64_t ThisVal = (Offset > Chunk) ? Chunk : Offset;
+    MachineInstr *MI =
+      BuildMI(MBB, MBBI, DL, TII.get(Opc), SystemZ::R15D)
+      .addReg(SystemZ::R15D).addImm(isSub ? -ThisVal : ThisVal);
+    // The PSW implicit def is dead.
+    MI->getOperand(3).setIsDead();
+    Offset -= ThisVal;
+  }
+}
+
+void SystemZFrameLowering::emitPrologue(MachineFunction &MF) const {
+  MachineBasicBlock &MBB = MF.front();   // Prolog goes in entry BB
+  MachineFrameInfo *MFI = MF.getFrameInfo();
+  const SystemZInstrInfo &TII =
+    *static_cast<const SystemZInstrInfo*>(MF.getTarget().getInstrInfo());
+  SystemZMachineFunctionInfo *SystemZMFI =
+    MF.getInfo<SystemZMachineFunctionInfo>();
+  MachineBasicBlock::iterator MBBI = MBB.begin();
+  DebugLoc DL = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
+
+  // Get the number of bytes to allocate from the FrameInfo.
+  // Note that area for callee-saved stuff is already allocated, thus we need to
+  // 'undo' the stack movement.
+  uint64_t StackSize = MFI->getStackSize();
+  StackSize -= SystemZMFI->getCalleeSavedFrameSize();
+
+  uint64_t NumBytes = StackSize - getOffsetOfLocalArea();
+
+  // Skip the callee-saved push instructions.
+  while (MBBI != MBB.end() &&
+         (MBBI->getOpcode() == SystemZ::MOV64mr ||
+          MBBI->getOpcode() == SystemZ::MOV64mrm))
+    ++MBBI;
+
+  if (MBBI != MBB.end())
+    DL = MBBI->getDebugLoc();
+
+  // adjust stack pointer: R15 -= numbytes
+  if (StackSize || MFI->hasCalls()) {
+    assert(MF.getRegInfo().isPhysRegUsed(SystemZ::R15D) &&
+           "Invalid stack frame calculation!");
+    emitSPUpdate(MBB, MBBI, -(int64_t)NumBytes, TII);
+  }
+
+  if (hasFP(MF)) {
+    // Update R11 with the new base value...
+    BuildMI(MBB, MBBI, DL, TII.get(SystemZ::MOV64rr), SystemZ::R11D)
+      .addReg(SystemZ::R15D);
+
+    // Mark the FramePtr as live-in in every block except the entry.
+    for (MachineFunction::iterator I = llvm::next(MF.begin()), E = MF.end();
+         I != E; ++I)
+      I->addLiveIn(SystemZ::R11D);
+
+  }
+}
+
+void SystemZFrameLowering::emitEpilogue(MachineFunction &MF,
+                                    MachineBasicBlock &MBB) const {
+  const MachineFrameInfo *MFI = MF.getFrameInfo();
+  MachineBasicBlock::iterator MBBI = prior(MBB.end());
+  const SystemZInstrInfo &TII =
+    *static_cast<const SystemZInstrInfo*>(MF.getTarget().getInstrInfo());
+  SystemZMachineFunctionInfo *SystemZMFI =
+    MF.getInfo<SystemZMachineFunctionInfo>();
+  unsigned RetOpcode = MBBI->getOpcode();
+
+  switch (RetOpcode) {
+  case SystemZ::RET: break;  // These are ok
+  default:
+    assert(0 && "Can only insert epilog into returning blocks");
+  }
+
+  // Get the number of bytes to allocate from the FrameInfo
+  // Note that area for callee-saved stuff is already allocated, thus we need to
+  // 'undo' the stack movement.
+  uint64_t StackSize =
+    MFI->getStackSize() - SystemZMFI->getCalleeSavedFrameSize();
+  uint64_t NumBytes = StackSize - getOffsetOfLocalArea();
+
+  // Skip the final terminator instruction.
+  while (MBBI != MBB.begin()) {
+    MachineBasicBlock::iterator PI = prior(MBBI);
+    --MBBI;
+    if (!PI->getDesc().isTerminator())
+      break;
+  }
+
+  // During callee-saved restores emission stack frame was not yet finialized
+  // (and thus - the stack size was unknown). Tune the offset having full stack
+  // size in hands.
+  if (StackSize || MFI->hasCalls()) {
+    assert((MBBI->getOpcode() == SystemZ::MOV64rmm ||
+            MBBI->getOpcode() == SystemZ::MOV64rm) &&
+           "Expected to see callee-save register restore code");
+    assert(MF.getRegInfo().isPhysRegUsed(SystemZ::R15D) &&
+           "Invalid stack frame calculation!");
+
+    unsigned i = 0;
+    MachineInstr &MI = *MBBI;
+    while (!MI.getOperand(i).isImm()) {
+      ++i;
+      assert(i < MI.getNumOperands() && "Unexpected restore code!");
+    }
+
+    uint64_t Offset = NumBytes + MI.getOperand(i).getImm();
+    // If Offset does not fit into 20-bit signed displacement field we need to
+    // emit some additional code...
+    if (Offset > 524287) {
+      // Fold the displacement into load instruction as much as possible.
+      NumBytes = Offset - 524287;
+      Offset = 524287;
+      emitSPUpdate(MBB, MBBI, NumBytes, TII);
+    }
+
+    MI.getOperand(i).ChangeToImmediate(Offset);
+  }
+}
+
+int SystemZFrameLowering::getFrameIndexOffset(const MachineFunction &MF,
+                                          int FI) const {
+  const MachineFrameInfo *MFI = MF.getFrameInfo();
+  const SystemZMachineFunctionInfo *SystemZMFI =
+    MF.getInfo<SystemZMachineFunctionInfo>();
+  int Offset = MFI->getObjectOffset(FI) + MFI->getOffsetAdjustment();
+  uint64_t StackSize = MFI->getStackSize();
+
+  // Fixed objects are really located in the "previous" frame.
+  if (FI < 0)
+    StackSize -= SystemZMFI->getCalleeSavedFrameSize();
+
+  Offset += StackSize - getOffsetOfLocalArea();
+
+  // Skip the register save area if we generated the stack frame.
+  if (StackSize || MFI->hasCalls())
+    Offset -= getOffsetOfLocalArea();
+
+  return Offset;
+}
+
+bool
+SystemZFrameLowering::spillCalleeSavedRegisters(MachineBasicBlock &MBB,
+                                            MachineBasicBlock::iterator MI,
+                                        const std::vector<CalleeSavedInfo> &CSI,
+                                          const TargetRegisterInfo *TRI) const {
+  if (CSI.empty())
+    return false;
+
+  DebugLoc DL;
+  if (MI != MBB.end()) DL = MI->getDebugLoc();
+
+  MachineFunction &MF = *MBB.getParent();
+  const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
+  SystemZMachineFunctionInfo *MFI = MF.getInfo<SystemZMachineFunctionInfo>();
+  unsigned CalleeFrameSize = 0;
+
+  // Scan the callee-saved and find the bounds of register spill area.
+  unsigned LowReg = 0, HighReg = 0, StartOffset = -1U, EndOffset = 0;
+  for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
+    unsigned Reg = CSI[i].getReg();
+    if (!SystemZ::FP64RegClass.contains(Reg)) {
+      unsigned Offset = RegSpillOffsets[Reg];
+      CalleeFrameSize += 8;
+      if (StartOffset > Offset) {
+        LowReg = Reg; StartOffset = Offset;
+      }
+      if (EndOffset < Offset) {
+        HighReg = Reg; EndOffset = RegSpillOffsets[Reg];
+      }
+    }
+  }
+
+  // Save information for epilogue inserter.
+  MFI->setCalleeSavedFrameSize(CalleeFrameSize);
+  MFI->setLowReg(LowReg); MFI->setHighReg(HighReg);
+
+  // Save GPRs
+  if (StartOffset) {
+    // Build a store instruction. Use STORE MULTIPLE instruction if there are many
+    // registers to store, otherwise - just STORE.
+    MachineInstrBuilder MIB =
+      BuildMI(MBB, MI, DL, TII.get((LowReg == HighReg ?
+                                    SystemZ::MOV64mr : SystemZ::MOV64mrm)));
+
+    // Add store operands.
+    MIB.addReg(SystemZ::R15D).addImm(StartOffset);
+    if (LowReg == HighReg)
+      MIB.addReg(0);
+    MIB.addReg(LowReg, RegState::Kill);
+    if (LowReg != HighReg)
+      MIB.addReg(HighReg, RegState::Kill);
+
+    // Do a second scan adding regs as being killed by instruction
+    for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
+      unsigned Reg = CSI[i].getReg();
+      // Add the callee-saved register as live-in. It's killed at the spill.
+      MBB.addLiveIn(Reg);
+      if (Reg != LowReg && Reg != HighReg)
+        MIB.addReg(Reg, RegState::ImplicitKill);
+    }
+  }
+
+  // Save FPRs
+  for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
+    unsigned Reg = CSI[i].getReg();
+    if (SystemZ::FP64RegClass.contains(Reg)) {
+      MBB.addLiveIn(Reg);
+      TII.storeRegToStackSlot(MBB, MI, Reg, true, CSI[i].getFrameIdx(),
+                              &SystemZ::FP64RegClass, TRI);
+    }
+  }
+
+  return true;
+}
+
+bool
+SystemZFrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
+                                              MachineBasicBlock::iterator MI,
+                                        const std::vector<CalleeSavedInfo> &CSI,
+                                          const TargetRegisterInfo *TRI) const {
+  if (CSI.empty())
+    return false;
+
+  DebugLoc DL;
+  if (MI != MBB.end()) DL = MI->getDebugLoc();
+
+  MachineFunction &MF = *MBB.getParent();
+  const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
+  SystemZMachineFunctionInfo *MFI = MF.getInfo<SystemZMachineFunctionInfo>();
+
+  // Restore FP registers
+  for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
+    unsigned Reg = CSI[i].getReg();
+    if (SystemZ::FP64RegClass.contains(Reg))
+      TII.loadRegFromStackSlot(MBB, MI, Reg, CSI[i].getFrameIdx(),
+                               &SystemZ::FP64RegClass, TRI);
+  }
+
+  // Restore GP registers
+  unsigned LowReg = MFI->getLowReg(), HighReg = MFI->getHighReg();
+  unsigned StartOffset = RegSpillOffsets[LowReg];
+
+  if (StartOffset) {
+    // Build a load instruction. Use LOAD MULTIPLE instruction if there are many
+    // registers to load, otherwise - just LOAD.
+    MachineInstrBuilder MIB =
+      BuildMI(MBB, MI, DL, TII.get((LowReg == HighReg ?
+                                    SystemZ::MOV64rm : SystemZ::MOV64rmm)));
+    // Add store operands.
+    MIB.addReg(LowReg, RegState::Define);
+    if (LowReg != HighReg)
+      MIB.addReg(HighReg, RegState::Define);
+
+    MIB.addReg(hasFP(MF) ? SystemZ::R11D : SystemZ::R15D);
+    MIB.addImm(StartOffset);
+    if (LowReg == HighReg)
+      MIB.addReg(0);
+
+    // Do a second scan adding regs as being defined by instruction
+    for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
+      unsigned Reg = CSI[i].getReg();
+      if (Reg != LowReg && Reg != HighReg)
+        MIB.addReg(Reg, RegState::ImplicitDefine);
+    }
+  }
+
+  return true;
+}
+
+void
+SystemZFrameLowering::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
+                                                       RegScavenger *RS) const {
+  // Determine whether R15/R14 will ever be clobbered inside the function. And
+  // if yes - mark it as 'callee' saved.
+  MachineFrameInfo *FFI = MF.getFrameInfo();
+  MachineRegisterInfo &MRI = MF.getRegInfo();
+
+  // Check whether high FPRs are ever used, if yes - we need to save R15 as
+  // well.
+  static const unsigned HighFPRs[] = {
+    SystemZ::F8L,  SystemZ::F9L,  SystemZ::F10L, SystemZ::F11L,
+    SystemZ::F12L, SystemZ::F13L, SystemZ::F14L, SystemZ::F15L,
+    SystemZ::F8S,  SystemZ::F9S,  SystemZ::F10S, SystemZ::F11S,
+    SystemZ::F12S, SystemZ::F13S, SystemZ::F14S, SystemZ::F15S,
+  };
+
+  bool HighFPRsUsed = false;
+  for (unsigned i = 0, e = array_lengthof(HighFPRs); i != e; ++i)
+    HighFPRsUsed |= MRI.isPhysRegUsed(HighFPRs[i]);
+
+  if (FFI->hasCalls())
+    /* FIXME: function is varargs */
+    /* FIXME: function grabs RA */
+    /* FIXME: function calls eh_return */
+    MRI.setPhysRegUsed(SystemZ::R14D);
+
+  if (HighFPRsUsed ||
+      FFI->hasCalls() ||
+      FFI->getObjectIndexEnd() != 0 || // Contains automatic variables
+      FFI->hasVarSizedObjects() // Function calls dynamic alloca's
+      /* FIXME: function is varargs */)
+    MRI.setPhysRegUsed(SystemZ::R15D);
+}