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
diff --git a/lib/Target/Mips/MipsFrameLowering.cpp b/lib/Target/Mips/MipsFrameLowering.cpp
new file mode 100644
index 0000000..a81f947
--- /dev/null
+++ b/lib/Target/Mips/MipsFrameLowering.cpp
@@ -0,0 +1,307 @@
+//=======- 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 = prior(MBB.end());
+ 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);
+ }
+}