Vendor import of llvm trunk r126079:

http://llvm.org/svn/llvm-project/llvm/trunk@126079

1 files changed, 314 insertions, 0 deletions

diff --git a/lib/Target/Mips/MipsFrameLowering.cpp b/lib/Target/Mips/MipsFrameLowering.cpp
new file mode 100644
index 0000000..87a097a
--- /dev/null
+++ b/lib/Target/Mips/MipsFrameLowering.cpp
@@ -0,0 +1,314 @@
+//=======- MipsFrameLowering.cpp - Mips 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 Mips implementation of TargetFrameLowering class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "MipsFrameLowering.h"
+#include "MipsInstrInfo.h"
+#include "MipsMachineFunction.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;
+
+
+//===----------------------------------------------------------------------===//
+//
+// 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.
+//
+//===----------------------------------------------------------------------===//
+
+// 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 DisableFramePointerElim(MF) || MFI->hasVarSizedObjects();
+}
+
+void MipsFrameLowering::adjustMipsStackFrame(MachineFunction &MF) const {
+  MachineFrameInfo *MFI = MF.getFrameInfo();
+  MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
+  const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
+  unsigned StackAlign = getStackAlignment();
+  unsigned RegSize = STI.isGP32bit() ? 4 : 8;
+  bool HasGP = MipsFI->needGPSaveRestore();
+
+  // Min and Max CSI FrameIndex.
+  int MinCSFI = -1, MaxCSFI = -1;
+
+  // See the description at MipsMachineFunction.h
+  int TopCPUSavedRegOff = -1, TopFPUSavedRegOff = -1;
+
+  // Replace the dummy '0' SPOffset by the negative offsets, as explained on
+  // LowerFormalArguments. Leaving '0' for while is necessary to avoid the
+  // approach done by calculateFrameObjectOffsets to the stack frame.
+  MipsFI->adjustLoadArgsFI(MFI);
+  MipsFI->adjustStoreVarArgsFI(MFI);
+
+  // It happens that the default stack frame allocation order does not directly
+  // map to the convention used for mips. So we must fix it. We move the callee
+  // save register slots after the local variables area, as described in the
+  // stack frame above.
+  unsigned CalleeSavedAreaSize = 0;
+  if (!CSI.empty()) {
+    MinCSFI = CSI[0].getFrameIdx();
+    MaxCSFI = CSI[CSI.size()-1].getFrameIdx();
+  }
+  for (unsigned i = 0, e = CSI.size(); i != e; ++i)
+    CalleeSavedAreaSize += MFI->getObjectAlignment(CSI[i].getFrameIdx());
+
+  unsigned StackOffset = HasGP ? (MipsFI->getGPStackOffset()+RegSize)
+                : (STI.isABI_O32() ? 16 : 0);
+
+  // Adjust local variables. They should come on the stack right
+  // after the arguments.
+  int LastOffsetFI = -1;
+  for (int i = 0, e = MFI->getObjectIndexEnd(); i != e; ++i) {
+    if (i >= MinCSFI && i <= MaxCSFI)
+      continue;
+    if (MFI->isDeadObjectIndex(i))
+      continue;
+    unsigned Offset =
+      StackOffset + MFI->getObjectOffset(i) - CalleeSavedAreaSize;
+    if (LastOffsetFI == -1)
+      LastOffsetFI = i;
+    if (Offset > MFI->getObjectOffset(LastOffsetFI))
+      LastOffsetFI = i;
+    MFI->setObjectOffset(i, Offset);
+  }
+
+  // Adjust CPU Callee Saved Registers Area. Registers RA and FP must
+  // be saved in this CPU Area. This whole area must be aligned to the
+  // default Stack Alignment requirements.
+  if (LastOffsetFI >= 0)
+    StackOffset = MFI->getObjectOffset(LastOffsetFI)+
+                  MFI->getObjectSize(LastOffsetFI);
+  StackOffset = ((StackOffset+StackAlign-1)/StackAlign*StackAlign);
+
+  for (unsigned i = 0, e = CSI.size(); i != e ; ++i) {
+    unsigned Reg = CSI[i].getReg();
+    if (!Mips::CPURegsRegisterClass->contains(Reg))
+      break;
+    MFI->setObjectOffset(CSI[i].getFrameIdx(), StackOffset);
+    TopCPUSavedRegOff = StackOffset;
+    StackOffset += MFI->getObjectAlignment(CSI[i].getFrameIdx());
+  }
+
+  // Stack locations for FP and RA. If only one of them is used,
+  // the space must be allocated for both, otherwise no space at all.
+  if (hasFP(MF) || MFI->adjustsStack()) {
+    // FP stack location
+    MFI->setObjectOffset(MFI->CreateStackObject(RegSize, RegSize, true),
+                         StackOffset);
+    MipsFI->setFPStackOffset(StackOffset);
+    TopCPUSavedRegOff = StackOffset;
+    StackOffset += RegSize;
+
+    // SP stack location
+    MFI->setObjectOffset(MFI->CreateStackObject(RegSize, RegSize, true),
+                         StackOffset);
+    MipsFI->setRAStackOffset(StackOffset);
+    StackOffset += RegSize;
+
+    if (MFI->adjustsStack())
+      TopCPUSavedRegOff += RegSize;
+  }
+
+  StackOffset = ((StackOffset+StackAlign-1)/StackAlign*StackAlign);
+
+  // Adjust FPU Callee Saved Registers Area. This Area must be
+  // aligned to the default Stack Alignment requirements.
+  for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
+    unsigned Reg = CSI[i].getReg();
+    if (Mips::CPURegsRegisterClass->contains(Reg))
+      continue;
+    MFI->setObjectOffset(CSI[i].getFrameIdx(), StackOffset);
+    TopFPUSavedRegOff = StackOffset;
+    StackOffset += MFI->getObjectAlignment(CSI[i].getFrameIdx());
+  }
+  StackOffset = ((StackOffset+StackAlign-1)/StackAlign*StackAlign);
+
+  // Update frame info
+  MFI->setStackSize(StackOffset);
+
+  // Recalculate the final tops offset. The final values must be '0'
+  // if there isn't a callee saved register for CPU or FPU, otherwise
+  // a negative offset is needed.
+  if (TopCPUSavedRegOff >= 0)
+    MipsFI->setCPUTopSavedRegOff(TopCPUSavedRegOff-StackOffset);
+
+  if (TopFPUSavedRegOff >= 0)
+    MipsFI->setFPUTopSavedRegOff(TopFPUSavedRegOff-StackOffset);
+}
+
+void MipsFrameLowering::emitPrologue(MachineFunction &MF) const {
+  MachineBasicBlock &MBB   = MF.front();
+  MachineFrameInfo *MFI    = MF.getFrameInfo();
+  MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
+  const MipsRegisterInfo *RegInfo =
+    static_cast<const MipsRegisterInfo*>(MF.getTarget().getRegisterInfo());
+  const MipsInstrInfo &TII =
+    *static_cast<const MipsInstrInfo*>(MF.getTarget().getInstrInfo());
+  MachineBasicBlock::iterator MBBI = MBB.begin();
+  DebugLoc dl = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
+  bool isPIC = (MF.getTarget().getRelocationModel() == Reloc::PIC_);
+
+  // Get the right frame order for Mips.
+  adjustMipsStackFrame(MF);
+
+  // Get the number of bytes to allocate from the FrameInfo.
+  unsigned StackSize = MFI->getStackSize();
+
+  // No need to allocate space on the stack.
+  if (StackSize == 0 && !MFI->adjustsStack()) return;
+
+  int FPOffset = MipsFI->getFPStackOffset();
+  int RAOffset = MipsFI->getRAStackOffset();
+
+  BuildMI(MBB, MBBI, dl, TII.get(Mips::NOREORDER));
+
+  // TODO: check need from GP here.
+  if (isPIC && STI.isABI_O32())
+    BuildMI(MBB, MBBI, dl, TII.get(Mips::CPLOAD))
+      .addReg(RegInfo->getPICCallReg());
+  BuildMI(MBB, MBBI, dl, TII.get(Mips::NOMACRO));
+
+  // Adjust stack : addi sp, sp, (-imm)
+  BuildMI(MBB, MBBI, dl, TII.get(Mips::ADDiu), Mips::SP)
+      .addReg(Mips::SP).addImm(-StackSize);
+
+  // Save the return address only if the function isnt a leaf one.
+  // sw  $ra, stack_loc($sp)
+  if (MFI->adjustsStack()) {
+    BuildMI(MBB, MBBI, dl, TII.get(Mips::SW))
+        .addReg(Mips::RA).addImm(RAOffset).addReg(Mips::SP);
+  }
+
+  // if framepointer enabled, save it and set it
+  // to point to the stack pointer
+  if (hasFP(MF)) {
+    // sw  $fp,stack_loc($sp)
+    BuildMI(MBB, MBBI, dl, TII.get(Mips::SW))
+      .addReg(Mips::FP).addImm(FPOffset).addReg(Mips::SP);
+
+    // move $fp, $sp
+    BuildMI(MBB, MBBI, dl, TII.get(Mips::ADDu), Mips::FP)
+      .addReg(Mips::SP).addReg(Mips::ZERO);
+  }
+
+  // Restore GP from the saved stack location
+  if (MipsFI->needGPSaveRestore())
+    BuildMI(MBB, MBBI, dl, TII.get(Mips::CPRESTORE))
+      .addImm(MipsFI->getGPStackOffset());
+}
+
+void MipsFrameLowering::emitEpilogue(MachineFunction &MF,
+                                 MachineBasicBlock &MBB) const {
+  MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
+  MachineFrameInfo *MFI            = MF.getFrameInfo();
+  MipsFunctionInfo *MipsFI         = MF.getInfo<MipsFunctionInfo>();
+  const MipsInstrInfo &TII =
+    *static_cast<const MipsInstrInfo*>(MF.getTarget().getInstrInfo());
+  DebugLoc dl = MBBI->getDebugLoc();
+
+  // Get the number of bytes from FrameInfo
+  int NumBytes = (int) MFI->getStackSize();
+
+  // Get the FI's where RA and FP are saved.
+  int FPOffset = MipsFI->getFPStackOffset();
+  int RAOffset = MipsFI->getRAStackOffset();
+
+  // if framepointer enabled, restore it and restore the
+  // stack pointer
+  if (hasFP(MF)) {
+    // move $sp, $fp
+    BuildMI(MBB, MBBI, dl, TII.get(Mips::ADDu), Mips::SP)
+      .addReg(Mips::FP).addReg(Mips::ZERO);
+
+    // lw  $fp,stack_loc($sp)
+    BuildMI(MBB, MBBI, dl, TII.get(Mips::LW), Mips::FP)
+      .addImm(FPOffset).addReg(Mips::SP);
+  }
+
+  // Restore the return address only if the function isnt a leaf one.
+  // lw  $ra, stack_loc($sp)
+  if (MFI->adjustsStack()) {
+    BuildMI(MBB, MBBI, dl, TII.get(Mips::LW), Mips::RA)
+      .addImm(RAOffset).addReg(Mips::SP);
+  }
+
+  // adjust stack  : insert addi sp, sp, (imm)
+  if (NumBytes) {
+    BuildMI(MBB, MBBI, dl, TII.get(Mips::ADDiu), Mips::SP)
+      .addReg(Mips::SP).addImm(NumBytes);
+  }
+}
+
+void MipsFrameLowering::
+processFunctionBeforeFrameFinalized(MachineFunction &MF) const {
+  const MipsRegisterInfo *RegInfo =
+    static_cast<const MipsRegisterInfo*>(MF.getTarget().getRegisterInfo());
+  RegInfo->processFunctionBeforeFrameFinalized(MF);
+}