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//=====- SystemZFrameInfo.cpp - SystemZ 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 SystemZ implementation of TargetFrameInfo class.
//
//===----------------------------------------------------------------------===//
#include "SystemZFrameInfo.h"
#include "SystemZInstrBuilder.h"
#include "SystemZInstrInfo.h"
#include "SystemZMachineFunctionInfo.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;
/// needsFP - 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 SystemZFrameInfo::hasFP(const MachineFunction &MF) const {
const MachineFrameInfo *MFI = MF.getFrameInfo();
return DisableFramePointerElim(MF) || MFI->hasVarSizedObjects();
}
/// emitSPUpdate - Emit a series of instructions to increment / decrement the
/// stack pointer by a constant value.
static
void emitSPUpdate(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
int64_t NumBytes, const TargetInstrInfo &TII) {
unsigned Opc; uint64_t Chunk;
bool isSub = NumBytes < 0;
uint64_t Offset = isSub ? -NumBytes : NumBytes;
if (Offset >= (1LL << 15) - 1) {
Opc = SystemZ::ADD64ri32;
Chunk = (1LL << 31) - 1;
} else {
Opc = SystemZ::ADD64ri16;
Chunk = (1LL << 15) - 1;
}
DebugLoc DL = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
while (Offset) {
uint64_t ThisVal = (Offset > Chunk) ? Chunk : Offset;
MachineInstr *MI =
BuildMI(MBB, MBBI, DL, TII.get(Opc), SystemZ::R15D)
.addReg(SystemZ::R15D).addImm(isSub ? -ThisVal : ThisVal);
// The PSW implicit def is dead.
MI->getOperand(3).setIsDead();
Offset -= ThisVal;
}
}
void SystemZFrameInfo::emitPrologue(MachineFunction &MF) const {
MachineBasicBlock &MBB = MF.front(); // Prolog goes in entry BB
const TargetFrameInfo &TFI = *MF.getTarget().getFrameInfo();
MachineFrameInfo *MFI = MF.getFrameInfo();
const SystemZInstrInfo &TII =
*static_cast<const SystemZInstrInfo*>(MF.getTarget().getInstrInfo());
SystemZMachineFunctionInfo *SystemZMFI =
MF.getInfo<SystemZMachineFunctionInfo>();
MachineBasicBlock::iterator MBBI = MBB.begin();
DebugLoc DL = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
// Get the number of bytes to allocate from the FrameInfo.
// Note that area for callee-saved stuff is already allocated, thus we need to
// 'undo' the stack movement.
uint64_t StackSize = MFI->getStackSize();
StackSize -= SystemZMFI->getCalleeSavedFrameSize();
uint64_t NumBytes = StackSize - TFI.getOffsetOfLocalArea();
// Skip the callee-saved push instructions.
while (MBBI != MBB.end() &&
(MBBI->getOpcode() == SystemZ::MOV64mr ||
MBBI->getOpcode() == SystemZ::MOV64mrm))
++MBBI;
if (MBBI != MBB.end())
DL = MBBI->getDebugLoc();
// adjust stack pointer: R15 -= numbytes
if (StackSize || MFI->hasCalls()) {
assert(MF.getRegInfo().isPhysRegUsed(SystemZ::R15D) &&
"Invalid stack frame calculation!");
emitSPUpdate(MBB, MBBI, -(int64_t)NumBytes, TII);
}
if (hasFP(MF)) {
// Update R11 with the new base value...
BuildMI(MBB, MBBI, DL, TII.get(SystemZ::MOV64rr), SystemZ::R11D)
.addReg(SystemZ::R15D);
// Mark the FramePtr as live-in in every block except the entry.
for (MachineFunction::iterator I = llvm::next(MF.begin()), E = MF.end();
I != E; ++I)
I->addLiveIn(SystemZ::R11D);
}
}
void SystemZFrameInfo::emitEpilogue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
const MachineFrameInfo *MFI = MF.getFrameInfo();
const TargetFrameInfo &TFI = *MF.getTarget().getFrameInfo();
MachineBasicBlock::iterator MBBI = prior(MBB.end());
const SystemZInstrInfo &TII =
*static_cast<const SystemZInstrInfo*>(MF.getTarget().getInstrInfo());
SystemZMachineFunctionInfo *SystemZMFI =
MF.getInfo<SystemZMachineFunctionInfo>();
unsigned RetOpcode = MBBI->getOpcode();
switch (RetOpcode) {
case SystemZ::RET: break; // These are ok
default:
assert(0 && "Can only insert epilog into returning blocks");
}
// Get the number of bytes to allocate from the FrameInfo
// Note that area for callee-saved stuff is already allocated, thus we need to
// 'undo' the stack movement.
uint64_t StackSize =
MFI->getStackSize() - SystemZMFI->getCalleeSavedFrameSize();
uint64_t NumBytes = StackSize - TFI.getOffsetOfLocalArea();
// Skip the final terminator instruction.
while (MBBI != MBB.begin()) {
MachineBasicBlock::iterator PI = prior(MBBI);
--MBBI;
if (!PI->getDesc().isTerminator())
break;
}
// During callee-saved restores emission stack frame was not yet finialized
// (and thus - the stack size was unknown). Tune the offset having full stack
// size in hands.
if (StackSize || MFI->hasCalls()) {
assert((MBBI->getOpcode() == SystemZ::MOV64rmm ||
MBBI->getOpcode() == SystemZ::MOV64rm) &&
"Expected to see callee-save register restore code");
assert(MF.getRegInfo().isPhysRegUsed(SystemZ::R15D) &&
"Invalid stack frame calculation!");
unsigned i = 0;
MachineInstr &MI = *MBBI;
while (!MI.getOperand(i).isImm()) {
++i;
assert(i < MI.getNumOperands() && "Unexpected restore code!");
}
uint64_t Offset = NumBytes + MI.getOperand(i).getImm();
// If Offset does not fit into 20-bit signed displacement field we need to
// emit some additional code...
if (Offset > 524287) {
// Fold the displacement into load instruction as much as possible.
NumBytes = Offset - 524287;
Offset = 524287;
emitSPUpdate(MBB, MBBI, NumBytes, TII);
}
MI.getOperand(i).ChangeToImmediate(Offset);
}
}
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