SparcFrameLowering.cpp revision 3574eca1b02600bac4e625297f4ecf745f4c4f32 
1//===-- SparcFrameLowering.cpp - Sparc Frame Information ------------------===//
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//
10// This file contains the Sparc implementation of TargetFrameLowering class.
11//
12//===----------------------------------------------------------------------===//
13
14#include "SparcFrameLowering.h"
15#include "SparcInstrInfo.h"
16#include "SparcMachineFunctionInfo.h"
17#include "llvm/Function.h"
18#include "llvm/CodeGen/MachineFrameInfo.h"
19#include "llvm/CodeGen/MachineFunction.h"
20#include "llvm/CodeGen/MachineInstrBuilder.h"
21#include "llvm/CodeGen/MachineModuleInfo.h"
22#include "llvm/CodeGen/MachineRegisterInfo.h"
23#include "llvm/DataLayout.h"
24#include "llvm/Target/TargetOptions.h"
25#include "llvm/Support/CommandLine.h"
26
27using namespace llvm;
28
29void SparcFrameLowering::emitPrologue(MachineFunction &MF) const {
30  MachineBasicBlock &MBB = MF.front();
31  MachineFrameInfo *MFI = MF.getFrameInfo();
32  const SparcInstrInfo &TII =
33    *static_cast<const SparcInstrInfo*>(MF.getTarget().getInstrInfo());
34  MachineBasicBlock::iterator MBBI = MBB.begin();
35  DebugLoc dl = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
36
37  // Get the number of bytes to allocate from the FrameInfo
38  int NumBytes = (int) MFI->getStackSize();
39
40  // Emit the correct save instruction based on the number of bytes in
41  // the frame. Minimum stack frame size according to V8 ABI is:
42  //   16 words for register window spill
43  //    1 word for address of returned aggregate-value
44  // +  6 words for passing parameters on the stack
45  // ----------
46  //   23 words * 4 bytes per word = 92 bytes
47  NumBytes += 92;
48
49  // Round up to next doubleword boundary -- a double-word boundary
50  // is required by the ABI.
51  NumBytes = (NumBytes + 7) & ~7;
52  NumBytes = -NumBytes;
53
54  if (NumBytes >= -4096) {
55    BuildMI(MBB, MBBI, dl, TII.get(SP::SAVEri), SP::O6)
56      .addReg(SP::O6).addImm(NumBytes);
57  } else {
58    // Emit this the hard way.  This clobbers G1 which we always know is
59    // available here.
60    unsigned OffHi = (unsigned)NumBytes >> 10U;
61    BuildMI(MBB, MBBI, dl, TII.get(SP::SETHIi), SP::G1).addImm(OffHi);
62    // Emit G1 = G1 + I6
63    BuildMI(MBB, MBBI, dl, TII.get(SP::ORri), SP::G1)
64      .addReg(SP::G1).addImm(NumBytes & ((1 << 10)-1));
65    BuildMI(MBB, MBBI, dl, TII.get(SP::SAVErr), SP::O6)
66      .addReg(SP::O6).addReg(SP::G1);
67  }
68}
69
70void SparcFrameLowering::emitEpilogue(MachineFunction &MF,
71                                  MachineBasicBlock &MBB) const {
72  MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
73  const SparcInstrInfo &TII =
74    *static_cast<const SparcInstrInfo*>(MF.getTarget().getInstrInfo());
75  DebugLoc dl = MBBI->getDebugLoc();
76  assert(MBBI->getOpcode() == SP::RETL &&
77         "Can only put epilog before 'retl' instruction!");
78  BuildMI(MBB, MBBI, dl, TII.get(SP::RESTORErr), SP::G0).addReg(SP::G0)
79    .addReg(SP::G0);
80}
81