--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lib/Target/Mips/MipsFrameLowering.cpp	Thu Dec 12 13:56:28 2013 +0900
@@ -0,0 +1,134 @@
+//===-- MipsFrameLowering.cpp - Mips 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 Mips implementation of TargetFrameLowering class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "MipsFrameLowering.h"
+#include "MCTargetDesc/MipsBaseInfo.h"
+#include "MipsAnalyzeImmediate.h"
+#include "MipsInstrInfo.h"
+#include "MipsMachineFunction.h"
+#include "MipsTargetMachine.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/Support/CommandLine.h"
+#include "llvm/Target/TargetOptions.h"
+
+using namespace llvm;
+
+
+//===----------------------------------------------------------------------===//
+//
+// Stack Frame Processing methods
+// +----------------------------+
+//
+// The stack is allocated decrementing the stack pointer on
+// the first instruction of a function prologue. Once decremented,
+// all stack references are done thought a positive offset
+// from the stack/frame pointer, so the stack is considering
+// to grow up! Otherwise terrible hacks would have to be made
+// to get this stack ABI compliant :)
+//
+//  The stack frame required by the ABI (after call):
+//  Offset
+//
+//  0                 ----------
+//  4                 Args to pass
+//  .                 saved $GP  (used in PIC)
+//  .                 Alloca allocations
+//  .                 Local Area
+//  .                 CPU "Callee Saved" Registers
+//  .                 saved FP
+//  .                 saved RA
+//  .                 FPU "Callee Saved" Registers
+//  StackSize         -----------
+//
+// Offset - offset from sp after stack allocation on function prologue
+//
+// The sp is the stack pointer subtracted/added from the stack size
+// at the Prologue/Epilogue
+//
+// References to the previous stack (to obtain arguments) are done
+// with offsets that exceeds the stack size: (stacksize+(4*(num_arg-1))
+//
+// Examples:
+// - reference to the actual stack frame
+//   for any local area var there is smt like : FI >= 0, StackOffset: 4
+//     sw REGX, 4(SP)
+//
+// - reference to previous stack frame
+//   suppose there's a load to the 5th arguments : FI < 0, StackOffset: 16.
+//   The emitted instruction will be something like:
+//     lw REGX, 16+StackSize(SP)
+//
+// Since the total stack size is unknown on LowerFormalArguments, all
+// stack references (ObjectOffset) created to reference the function
+// arguments, are negative numbers. This way, on eliminateFrameIndex it's
+// possible to detect those references and the offsets are adjusted to
+// their real location.
+//
+//===----------------------------------------------------------------------===//
+
+const MipsFrameLowering *MipsFrameLowering::create(MipsTargetMachine &TM,
+                                                   const MipsSubtarget &ST) {
+  if (TM.getSubtargetImpl()->inMips16Mode())
+    return llvm::createMips16FrameLowering(ST);
+
+  return llvm::createMipsSEFrameLowering(ST);
+}
+
+// hasFP - 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 MipsFrameLowering::hasFP(const MachineFunction &MF) const {
+  const MachineFrameInfo *MFI = MF.getFrameInfo();
+  return MF.getTarget().Options.DisableFramePointerElim(MF) ||
+      MFI->hasVarSizedObjects() || MFI->isFrameAddressTaken();
+}
+
+uint64_t MipsFrameLowering::estimateStackSize(const MachineFunction &MF) const {
+  const MachineFrameInfo *MFI = MF.getFrameInfo();
+  const TargetRegisterInfo &TRI = *MF.getTarget().getRegisterInfo();
+
+  int64_t Offset = 0;
+
+  // Iterate over fixed sized objects.
+  for (int I = MFI->getObjectIndexBegin(); I != 0; ++I)
+    Offset = std::max(Offset, -MFI->getObjectOffset(I));
+
+  // Conservatively assume all callee-saved registers will be saved.
+  for (const uint16_t *R = TRI.getCalleeSavedRegs(&MF); *R; ++R) {
+    unsigned Size = TRI.getMinimalPhysRegClass(*R)->getSize();
+    Offset = RoundUpToAlignment(Offset + Size, Size);
+  }
+
+  unsigned MaxAlign = MFI->getMaxAlignment();
+
+  // Check that MaxAlign is not zero if there is a stack object that is not a
+  // callee-saved spill.
+  assert(!MFI->getObjectIndexEnd() || MaxAlign);
+
+  // Iterate over other objects.
+  for (unsigned I = 0, E = MFI->getObjectIndexEnd(); I != E; ++I)
+    Offset = RoundUpToAlignment(Offset + MFI->getObjectSize(I), MaxAlign);
+
+  // Call frame.
+  if (MFI->adjustsStack() && hasReservedCallFrame(MF))
+    Offset = RoundUpToAlignment(Offset + MFI->getMaxCallFrameSize(),
+                                std::max(MaxAlign, getStackAlignment()));
+
+  return RoundUpToAlignment(Offset, getStackAlignment());
+}