Imported Upstream version 6.0.0.172

Former-commit-id: f3cc9b82f3e5bd8f0fd3ebc098f789556b44e9cd

external/llvm/lib/Target/MSP430/MSP430FrameLowering.cpp

@@ -0,0 +1,300 @@
+//===-- MSP430FrameLowering.cpp - MSP430 Frame Information ----------------===//
+//
+//                     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 MSP430 implementation of TargetFrameLowering class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "MSP430FrameLowering.h"
+#include "MSP430InstrInfo.h"
+#include "MSP430MachineFunctionInfo.h"
+#include "MSP430Subtarget.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/IR/DataLayout.h"
+#include "llvm/IR/Function.h"
+#include "llvm/Target/TargetOptions.h"
+
+using namespace llvm;
+
+bool MSP430FrameLowering::hasFP(const MachineFunction &MF) const {
+  const MachineFrameInfo &MFI = MF.getFrameInfo();
+
+  return (MF.getTarget().Options.DisableFramePointerElim(MF) ||
+          MF.getFrameInfo().hasVarSizedObjects() ||
+          MFI.isFrameAddressTaken());
+}
+
+bool MSP430FrameLowering::hasReservedCallFrame(const MachineFunction &MF) const {
+  return !MF.getFrameInfo().hasVarSizedObjects();
+}
+
+void MSP430FrameLowering::emitPrologue(MachineFunction &MF,
+                                       MachineBasicBlock &MBB) const {
+  assert(&MF.front() == &MBB && "Shrink-wrapping not yet supported");
+  MachineFrameInfo &MFI = MF.getFrameInfo();
+  MSP430MachineFunctionInfo *MSP430FI = MF.getInfo<MSP430MachineFunctionInfo>();
+  const MSP430InstrInfo &TII =
+      *static_cast<const MSP430InstrInfo *>(MF.getSubtarget().getInstrInfo());
+
+  MachineBasicBlock::iterator MBBI = MBB.begin();
+  DebugLoc DL = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
+
+  // Get the number of bytes to allocate from the FrameInfo.
+  uint64_t StackSize = MFI.getStackSize();
+
+  uint64_t NumBytes = 0;
+  if (hasFP(MF)) {
+    // Calculate required stack adjustment
+    uint64_t FrameSize = StackSize - 2;
+    NumBytes = FrameSize - MSP430FI->getCalleeSavedFrameSize();
+
+    // Get the offset of the stack slot for the EBP register... which is
+    // guaranteed to be the last slot by processFunctionBeforeFrameFinalized.
+    // Update the frame offset adjustment.
+    MFI.setOffsetAdjustment(-NumBytes);
+
+    // Save FP into the appropriate stack slot...
+    BuildMI(MBB, MBBI, DL, TII.get(MSP430::PUSH16r))
+      .addReg(MSP430::FP, RegState::Kill);
+
+    // Update FP with the new base value...
+    BuildMI(MBB, MBBI, DL, TII.get(MSP430::MOV16rr), MSP430::FP)
+      .addReg(MSP430::SP);
+
+    // Mark the FramePtr as live-in in every block except the entry.
+    for (MachineFunction::iterator I = std::next(MF.begin()), E = MF.end();
+         I != E; ++I)
+      I->addLiveIn(MSP430::FP);
+
+  } else
+    NumBytes = StackSize - MSP430FI->getCalleeSavedFrameSize();
+
+  // Skip the callee-saved push instructions.
+  while (MBBI != MBB.end() && (MBBI->getOpcode() == MSP430::PUSH16r))
+    ++MBBI;
+
+  if (MBBI != MBB.end())
+    DL = MBBI->getDebugLoc();
+
+  if (NumBytes) { // adjust stack pointer: SP -= numbytes
+    // If there is an SUB16ri of SP immediately before this instruction, merge
+    // the two.
+    //NumBytes -= mergeSPUpdates(MBB, MBBI, true);
+    // If there is an ADD16ri or SUB16ri of SP immediately after this
+    // instruction, merge the two instructions.
+    // mergeSPUpdatesDown(MBB, MBBI, &NumBytes);
+
+    if (NumBytes) {
+      MachineInstr *MI =
+        BuildMI(MBB, MBBI, DL, TII.get(MSP430::SUB16ri), MSP430::SP)
+        .addReg(MSP430::SP).addImm(NumBytes);
+      // The SRW implicit def is dead.
+      MI->getOperand(3).setIsDead();
+    }
+  }
+}
+
+void MSP430FrameLowering::emitEpilogue(MachineFunction &MF,
+                                       MachineBasicBlock &MBB) const {
+  const MachineFrameInfo &MFI = MF.getFrameInfo();
+  MSP430MachineFunctionInfo *MSP430FI = MF.getInfo<MSP430MachineFunctionInfo>();
+  const MSP430InstrInfo &TII =
+      *static_cast<const MSP430InstrInfo *>(MF.getSubtarget().getInstrInfo());
+
+  MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
+  unsigned RetOpcode = MBBI->getOpcode();
+  DebugLoc DL = MBBI->getDebugLoc();
+
+  switch (RetOpcode) {
+  case MSP430::RET:
+  case MSP430::RETI: break;  // These are ok
+  default:
+    llvm_unreachable("Can only insert epilog into returning blocks");
+  }
+
+  // Get the number of bytes to allocate from the FrameInfo
+  uint64_t StackSize = MFI.getStackSize();
+  unsigned CSSize = MSP430FI->getCalleeSavedFrameSize();
+  uint64_t NumBytes = 0;
+
+  if (hasFP(MF)) {
+    // Calculate required stack adjustment
+    uint64_t FrameSize = StackSize - 2;
+    NumBytes = FrameSize - CSSize;
+
+    // pop FP.
+    BuildMI(MBB, MBBI, DL, TII.get(MSP430::POP16r), MSP430::FP);
+  } else
+    NumBytes = StackSize - CSSize;
+
+  // Skip the callee-saved pop instructions.
+  while (MBBI != MBB.begin()) {
+    MachineBasicBlock::iterator PI = std::prev(MBBI);
+    unsigned Opc = PI->getOpcode();
+    if (Opc != MSP430::POP16r && !PI->isTerminator())
+      break;
+    --MBBI;
+  }
+
+  DL = MBBI->getDebugLoc();
+
+  // If there is an ADD16ri or SUB16ri of SP immediately before this
+  // instruction, merge the two instructions.
+  //if (NumBytes || MFI.hasVarSizedObjects())
+  //  mergeSPUpdatesUp(MBB, MBBI, StackPtr, &NumBytes);
+
+  if (MFI.hasVarSizedObjects()) {
+    BuildMI(MBB, MBBI, DL,
+            TII.get(MSP430::MOV16rr), MSP430::SP).addReg(MSP430::FP);
+    if (CSSize) {
+      MachineInstr *MI =
+        BuildMI(MBB, MBBI, DL,
+                TII.get(MSP430::SUB16ri), MSP430::SP)
+        .addReg(MSP430::SP).addImm(CSSize);
+      // The SRW implicit def is dead.
+      MI->getOperand(3).setIsDead();
+    }
+  } else {
+    // adjust stack pointer back: SP += numbytes
+    if (NumBytes) {
+      MachineInstr *MI =
+        BuildMI(MBB, MBBI, DL, TII.get(MSP430::ADD16ri), MSP430::SP)
+        .addReg(MSP430::SP).addImm(NumBytes);
+      // The SRW implicit def is dead.
+      MI->getOperand(3).setIsDead();
+    }
+  }
+}
+
+// FIXME: Can we eleminate these in favour of generic code?
+bool
+MSP430FrameLowering::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.getSubtarget().getInstrInfo();
+  MSP430MachineFunctionInfo *MFI = MF.getInfo<MSP430MachineFunctionInfo>();
+  MFI->setCalleeSavedFrameSize(CSI.size() * 2);
+
+  for (unsigned i = CSI.size(); i != 0; --i) {
+    unsigned Reg = CSI[i-1].getReg();
+    // Add the callee-saved register as live-in. It's killed at the spill.
+    MBB.addLiveIn(Reg);
+    BuildMI(MBB, MI, DL, TII.get(MSP430::PUSH16r))
+      .addReg(Reg, RegState::Kill);
+  }
+  return true;
+}
+
+bool
+MSP430FrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
+                                                 MachineBasicBlock::iterator MI,
+                                        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.getSubtarget().getInstrInfo();
+
+  for (unsigned i = 0, e = CSI.size(); i != e; ++i)
+    BuildMI(MBB, MI, DL, TII.get(MSP430::POP16r), CSI[i].getReg());
+
+  return true;
+}
+
+MachineBasicBlock::iterator MSP430FrameLowering::eliminateCallFramePseudoInstr(
+    MachineFunction &MF, MachineBasicBlock &MBB,
+    MachineBasicBlock::iterator I) const {
+  const MSP430InstrInfo &TII =
+      *static_cast<const MSP430InstrInfo *>(MF.getSubtarget().getInstrInfo());
+  unsigned StackAlign = getStackAlignment();
+
+  if (!hasReservedCallFrame(MF)) {
+    // If the stack pointer can be changed after prologue, turn the
+    // adjcallstackup instruction into a 'sub SP, <amt>' and the
+    // adjcallstackdown instruction into 'add SP, <amt>'
+    // TODO: consider using push / pop instead of sub + store / add
+    MachineInstr &Old = *I;
+    uint64_t Amount = TII.getFrameSize(Old);
+    if (Amount != 0) {
+      // We need to keep the stack aligned properly.  To do this, we round the
+      // amount of space needed for the outgoing arguments up to the next
+      // alignment boundary.
+      Amount = (Amount+StackAlign-1)/StackAlign*StackAlign;
+
+      MachineInstr *New = nullptr;
+      if (Old.getOpcode() == TII.getCallFrameSetupOpcode()) {
+        New =
+            BuildMI(MF, Old.getDebugLoc(), TII.get(MSP430::SUB16ri), MSP430::SP)
+                .addReg(MSP430::SP)
+                .addImm(Amount);
+      } else {
+        assert(Old.getOpcode() == TII.getCallFrameDestroyOpcode());
+        // factor out the amount the callee already popped.
+        Amount -= TII.getFramePoppedByCallee(Old);
+        if (Amount)
+          New = BuildMI(MF, Old.getDebugLoc(), TII.get(MSP430::ADD16ri),
+                        MSP430::SP)
+                    .addReg(MSP430::SP)
+                    .addImm(Amount);
+      }
+
+      if (New) {
+        // The SRW implicit def is dead.
+        New->getOperand(3).setIsDead();
+
+        // Replace the pseudo instruction with a new instruction...
+        MBB.insert(I, New);
+      }
+    }
+  } else if (I->getOpcode() == TII.getCallFrameDestroyOpcode()) {
+    // If we are performing frame pointer elimination and if the callee pops
+    // something off the stack pointer, add it back.
+    if (uint64_t CalleeAmt = TII.getFramePoppedByCallee(*I)) {
+      MachineInstr &Old = *I;
+      MachineInstr *New =
+          BuildMI(MF, Old.getDebugLoc(), TII.get(MSP430::SUB16ri), MSP430::SP)
+              .addReg(MSP430::SP)
+              .addImm(CalleeAmt);
+      // The SRW implicit def is dead.
+      New->getOperand(3).setIsDead();
+
+      MBB.insert(I, New);
+    }
+  }
+
+  return MBB.erase(I);
+}
+
+void
+MSP430FrameLowering::processFunctionBeforeFrameFinalized(MachineFunction &MF,
+                                                         RegScavenger *) const {
+  // Create a frame entry for the FP register that must be saved.
+  if (hasFP(MF)) {
+    int FrameIdx = MF.getFrameInfo().CreateFixedObject(2, -4, true);
+    (void)FrameIdx;
+    assert(FrameIdx == MF.getFrameInfo().getObjectIndexBegin() &&
+           "Slot for FP register must be last in order to be found!");
+  }
+}