mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-08-30 21:29:28 +00:00
PEI inserts a save/restore sequence for the link register, according to the information it gets from the MachineRegisterInfo. MachineRegisterInfo is populated by the VirtRegMap pass. This pass was not aware of noreturn calls and was registering the definitions of these calls the same way as regular operations. Modify VirtRegPass so that it does not set the isPhysRegUsed information for registers only defined by noreturn calls. The rational is that a noreturn call is the "last instruction" of the program (if it returns the behavior is undefined), so everything that is defined by it cannot be used and will not interfere with anything else. Therefore, it is pointless to account for then. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191349 91177308-0d34-0410-b5e6-96231b3b80d8
396 lines
14 KiB
C++
396 lines
14 KiB
C++
//===-- llvm/CodeGen/VirtRegMap.cpp - Virtual Register Map ----------------===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This file implements the VirtRegMap class.
|
|
//
|
|
// It also contains implementations of the Spiller interface, which, given a
|
|
// virtual register map and a machine function, eliminates all virtual
|
|
// references by replacing them with physical register references - adding spill
|
|
// code as necessary.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#define DEBUG_TYPE "regalloc"
|
|
#include "llvm/CodeGen/VirtRegMap.h"
|
|
#include "LiveDebugVariables.h"
|
|
#include "llvm/ADT/STLExtras.h"
|
|
#include "llvm/ADT/Statistic.h"
|
|
#include "llvm/CodeGen/LiveIntervalAnalysis.h"
|
|
#include "llvm/CodeGen/LiveStackAnalysis.h"
|
|
#include "llvm/CodeGen/MachineFrameInfo.h"
|
|
#include "llvm/CodeGen/MachineFunction.h"
|
|
#include "llvm/CodeGen/MachineInstrBuilder.h"
|
|
#include "llvm/CodeGen/MachineRegisterInfo.h"
|
|
#include "llvm/CodeGen/Passes.h"
|
|
#include "llvm/IR/Function.h"
|
|
#include "llvm/Support/CommandLine.h"
|
|
#include "llvm/Support/Compiler.h"
|
|
#include "llvm/Support/Debug.h"
|
|
#include "llvm/Support/raw_ostream.h"
|
|
#include "llvm/Target/TargetInstrInfo.h"
|
|
#include "llvm/Target/TargetMachine.h"
|
|
#include "llvm/Target/TargetRegisterInfo.h"
|
|
#include <algorithm>
|
|
using namespace llvm;
|
|
|
|
STATISTIC(NumSpillSlots, "Number of spill slots allocated");
|
|
STATISTIC(NumIdCopies, "Number of identity moves eliminated after rewriting");
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// VirtRegMap implementation
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
char VirtRegMap::ID = 0;
|
|
|
|
INITIALIZE_PASS(VirtRegMap, "virtregmap", "Virtual Register Map", false, false)
|
|
|
|
bool VirtRegMap::runOnMachineFunction(MachineFunction &mf) {
|
|
MRI = &mf.getRegInfo();
|
|
TII = mf.getTarget().getInstrInfo();
|
|
TRI = mf.getTarget().getRegisterInfo();
|
|
MF = &mf;
|
|
|
|
Virt2PhysMap.clear();
|
|
Virt2StackSlotMap.clear();
|
|
Virt2SplitMap.clear();
|
|
|
|
grow();
|
|
return false;
|
|
}
|
|
|
|
void VirtRegMap::grow() {
|
|
unsigned NumRegs = MF->getRegInfo().getNumVirtRegs();
|
|
Virt2PhysMap.resize(NumRegs);
|
|
Virt2StackSlotMap.resize(NumRegs);
|
|
Virt2SplitMap.resize(NumRegs);
|
|
}
|
|
|
|
unsigned VirtRegMap::createSpillSlot(const TargetRegisterClass *RC) {
|
|
int SS = MF->getFrameInfo()->CreateSpillStackObject(RC->getSize(),
|
|
RC->getAlignment());
|
|
++NumSpillSlots;
|
|
return SS;
|
|
}
|
|
|
|
bool VirtRegMap::hasPreferredPhys(unsigned VirtReg) {
|
|
unsigned Hint = MRI->getSimpleHint(VirtReg);
|
|
if (!Hint)
|
|
return 0;
|
|
if (TargetRegisterInfo::isVirtualRegister(Hint))
|
|
Hint = getPhys(Hint);
|
|
return getPhys(VirtReg) == Hint;
|
|
}
|
|
|
|
bool VirtRegMap::hasKnownPreference(unsigned VirtReg) {
|
|
std::pair<unsigned, unsigned> Hint = MRI->getRegAllocationHint(VirtReg);
|
|
if (TargetRegisterInfo::isPhysicalRegister(Hint.second))
|
|
return true;
|
|
if (TargetRegisterInfo::isVirtualRegister(Hint.second))
|
|
return hasPhys(Hint.second);
|
|
return false;
|
|
}
|
|
|
|
int VirtRegMap::assignVirt2StackSlot(unsigned virtReg) {
|
|
assert(TargetRegisterInfo::isVirtualRegister(virtReg));
|
|
assert(Virt2StackSlotMap[virtReg] == NO_STACK_SLOT &&
|
|
"attempt to assign stack slot to already spilled register");
|
|
const TargetRegisterClass* RC = MF->getRegInfo().getRegClass(virtReg);
|
|
return Virt2StackSlotMap[virtReg] = createSpillSlot(RC);
|
|
}
|
|
|
|
void VirtRegMap::assignVirt2StackSlot(unsigned virtReg, int SS) {
|
|
assert(TargetRegisterInfo::isVirtualRegister(virtReg));
|
|
assert(Virt2StackSlotMap[virtReg] == NO_STACK_SLOT &&
|
|
"attempt to assign stack slot to already spilled register");
|
|
assert((SS >= 0 ||
|
|
(SS >= MF->getFrameInfo()->getObjectIndexBegin())) &&
|
|
"illegal fixed frame index");
|
|
Virt2StackSlotMap[virtReg] = SS;
|
|
}
|
|
|
|
void VirtRegMap::print(raw_ostream &OS, const Module*) const {
|
|
OS << "********** REGISTER MAP **********\n";
|
|
for (unsigned i = 0, e = MRI->getNumVirtRegs(); i != e; ++i) {
|
|
unsigned Reg = TargetRegisterInfo::index2VirtReg(i);
|
|
if (Virt2PhysMap[Reg] != (unsigned)VirtRegMap::NO_PHYS_REG) {
|
|
OS << '[' << PrintReg(Reg, TRI) << " -> "
|
|
<< PrintReg(Virt2PhysMap[Reg], TRI) << "] "
|
|
<< MRI->getRegClass(Reg)->getName() << "\n";
|
|
}
|
|
}
|
|
|
|
for (unsigned i = 0, e = MRI->getNumVirtRegs(); i != e; ++i) {
|
|
unsigned Reg = TargetRegisterInfo::index2VirtReg(i);
|
|
if (Virt2StackSlotMap[Reg] != VirtRegMap::NO_STACK_SLOT) {
|
|
OS << '[' << PrintReg(Reg, TRI) << " -> fi#" << Virt2StackSlotMap[Reg]
|
|
<< "] " << MRI->getRegClass(Reg)->getName() << "\n";
|
|
}
|
|
}
|
|
OS << '\n';
|
|
}
|
|
|
|
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
|
|
void VirtRegMap::dump() const {
|
|
print(dbgs());
|
|
}
|
|
#endif
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// VirtRegRewriter
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// The VirtRegRewriter is the last of the register allocator passes.
|
|
// It rewrites virtual registers to physical registers as specified in the
|
|
// VirtRegMap analysis. It also updates live-in information on basic blocks
|
|
// according to LiveIntervals.
|
|
//
|
|
namespace {
|
|
class VirtRegRewriter : public MachineFunctionPass {
|
|
MachineFunction *MF;
|
|
const TargetMachine *TM;
|
|
const TargetRegisterInfo *TRI;
|
|
const TargetInstrInfo *TII;
|
|
MachineRegisterInfo *MRI;
|
|
SlotIndexes *Indexes;
|
|
LiveIntervals *LIS;
|
|
VirtRegMap *VRM;
|
|
|
|
void rewrite();
|
|
void addMBBLiveIns();
|
|
public:
|
|
static char ID;
|
|
VirtRegRewriter() : MachineFunctionPass(ID) {}
|
|
|
|
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
|
|
|
|
virtual bool runOnMachineFunction(MachineFunction&);
|
|
};
|
|
} // end anonymous namespace
|
|
|
|
char &llvm::VirtRegRewriterID = VirtRegRewriter::ID;
|
|
|
|
INITIALIZE_PASS_BEGIN(VirtRegRewriter, "virtregrewriter",
|
|
"Virtual Register Rewriter", false, false)
|
|
INITIALIZE_PASS_DEPENDENCY(SlotIndexes)
|
|
INITIALIZE_PASS_DEPENDENCY(LiveIntervals)
|
|
INITIALIZE_PASS_DEPENDENCY(LiveDebugVariables)
|
|
INITIALIZE_PASS_DEPENDENCY(LiveStacks)
|
|
INITIALIZE_PASS_DEPENDENCY(VirtRegMap)
|
|
INITIALIZE_PASS_END(VirtRegRewriter, "virtregrewriter",
|
|
"Virtual Register Rewriter", false, false)
|
|
|
|
char VirtRegRewriter::ID = 0;
|
|
|
|
void VirtRegRewriter::getAnalysisUsage(AnalysisUsage &AU) const {
|
|
AU.setPreservesCFG();
|
|
AU.addRequired<LiveIntervals>();
|
|
AU.addRequired<SlotIndexes>();
|
|
AU.addPreserved<SlotIndexes>();
|
|
AU.addRequired<LiveDebugVariables>();
|
|
AU.addRequired<LiveStacks>();
|
|
AU.addPreserved<LiveStacks>();
|
|
AU.addRequired<VirtRegMap>();
|
|
MachineFunctionPass::getAnalysisUsage(AU);
|
|
}
|
|
|
|
bool VirtRegRewriter::runOnMachineFunction(MachineFunction &fn) {
|
|
MF = &fn;
|
|
TM = &MF->getTarget();
|
|
TRI = TM->getRegisterInfo();
|
|
TII = TM->getInstrInfo();
|
|
MRI = &MF->getRegInfo();
|
|
Indexes = &getAnalysis<SlotIndexes>();
|
|
LIS = &getAnalysis<LiveIntervals>();
|
|
VRM = &getAnalysis<VirtRegMap>();
|
|
DEBUG(dbgs() << "********** REWRITE VIRTUAL REGISTERS **********\n"
|
|
<< "********** Function: "
|
|
<< MF->getName() << '\n');
|
|
DEBUG(VRM->dump());
|
|
|
|
// Add kill flags while we still have virtual registers.
|
|
LIS->addKillFlags(VRM);
|
|
|
|
// Live-in lists on basic blocks are required for physregs.
|
|
addMBBLiveIns();
|
|
|
|
// Rewrite virtual registers.
|
|
rewrite();
|
|
|
|
// Write out new DBG_VALUE instructions.
|
|
getAnalysis<LiveDebugVariables>().emitDebugValues(VRM);
|
|
|
|
// All machine operands and other references to virtual registers have been
|
|
// replaced. Remove the virtual registers and release all the transient data.
|
|
VRM->clearAllVirt();
|
|
MRI->clearVirtRegs();
|
|
return true;
|
|
}
|
|
|
|
// Compute MBB live-in lists from virtual register live ranges and their
|
|
// assignments.
|
|
void VirtRegRewriter::addMBBLiveIns() {
|
|
SmallVector<MachineBasicBlock*, 16> LiveIn;
|
|
for (unsigned Idx = 0, IdxE = MRI->getNumVirtRegs(); Idx != IdxE; ++Idx) {
|
|
unsigned VirtReg = TargetRegisterInfo::index2VirtReg(Idx);
|
|
if (MRI->reg_nodbg_empty(VirtReg))
|
|
continue;
|
|
LiveInterval &LI = LIS->getInterval(VirtReg);
|
|
if (LI.empty() || LIS->intervalIsInOneMBB(LI))
|
|
continue;
|
|
// This is a virtual register that is live across basic blocks. Its
|
|
// assigned PhysReg must be marked as live-in to those blocks.
|
|
unsigned PhysReg = VRM->getPhys(VirtReg);
|
|
assert(PhysReg != VirtRegMap::NO_PHYS_REG && "Unmapped virtual register.");
|
|
|
|
// Scan the segments of LI.
|
|
for (LiveInterval::const_iterator I = LI.begin(), E = LI.end(); I != E;
|
|
++I) {
|
|
if (!Indexes->findLiveInMBBs(I->start, I->end, LiveIn))
|
|
continue;
|
|
for (unsigned i = 0, e = LiveIn.size(); i != e; ++i)
|
|
if (!LiveIn[i]->isLiveIn(PhysReg))
|
|
LiveIn[i]->addLiveIn(PhysReg);
|
|
LiveIn.clear();
|
|
}
|
|
}
|
|
}
|
|
|
|
void VirtRegRewriter::rewrite() {
|
|
SmallVector<unsigned, 8> SuperDeads;
|
|
SmallVector<unsigned, 8> SuperDefs;
|
|
SmallVector<unsigned, 8> SuperKills;
|
|
SmallPtrSet<const MachineInstr *, 4> NoReturnInsts;
|
|
|
|
for (MachineFunction::iterator MBBI = MF->begin(), MBBE = MF->end();
|
|
MBBI != MBBE; ++MBBI) {
|
|
DEBUG(MBBI->print(dbgs(), Indexes));
|
|
bool IsExitBB = MBBI->succ_empty();
|
|
for (MachineBasicBlock::instr_iterator
|
|
MII = MBBI->instr_begin(), MIE = MBBI->instr_end(); MII != MIE;) {
|
|
MachineInstr *MI = MII;
|
|
++MII;
|
|
|
|
// Check if this instruction is a call to a noreturn function.
|
|
// If so, all the definitions set by this instruction can be ignored.
|
|
if (IsExitBB && MI->isCall())
|
|
for (MachineInstr::mop_iterator MOI = MI->operands_begin(),
|
|
MOE = MI->operands_end(); MOI != MOE; ++MOI) {
|
|
MachineOperand &MO = *MOI;
|
|
if (!MO.isGlobal())
|
|
continue;
|
|
const Function *Func = dyn_cast<Function>(MO.getGlobal());
|
|
if (!Func || !Func->hasFnAttribute(Attribute::NoReturn))
|
|
continue;
|
|
NoReturnInsts.insert(MI);
|
|
break;
|
|
}
|
|
|
|
for (MachineInstr::mop_iterator MOI = MI->operands_begin(),
|
|
MOE = MI->operands_end(); MOI != MOE; ++MOI) {
|
|
MachineOperand &MO = *MOI;
|
|
|
|
// Make sure MRI knows about registers clobbered by regmasks.
|
|
if (MO.isRegMask())
|
|
MRI->addPhysRegsUsedFromRegMask(MO.getRegMask());
|
|
|
|
if (!MO.isReg() || !TargetRegisterInfo::isVirtualRegister(MO.getReg()))
|
|
continue;
|
|
unsigned VirtReg = MO.getReg();
|
|
unsigned PhysReg = VRM->getPhys(VirtReg);
|
|
assert(PhysReg != VirtRegMap::NO_PHYS_REG &&
|
|
"Instruction uses unmapped VirtReg");
|
|
assert(!MRI->isReserved(PhysReg) && "Reserved register assignment");
|
|
|
|
// Preserve semantics of sub-register operands.
|
|
if (MO.getSubReg()) {
|
|
// A virtual register kill refers to the whole register, so we may
|
|
// have to add <imp-use,kill> operands for the super-register. A
|
|
// partial redef always kills and redefines the super-register.
|
|
if (MO.readsReg() && (MO.isDef() || MO.isKill()))
|
|
SuperKills.push_back(PhysReg);
|
|
|
|
if (MO.isDef()) {
|
|
// The <def,undef> flag only makes sense for sub-register defs, and
|
|
// we are substituting a full physreg. An <imp-use,kill> operand
|
|
// from the SuperKills list will represent the partial read of the
|
|
// super-register.
|
|
MO.setIsUndef(false);
|
|
|
|
// Also add implicit defs for the super-register.
|
|
if (MO.isDead())
|
|
SuperDeads.push_back(PhysReg);
|
|
else
|
|
SuperDefs.push_back(PhysReg);
|
|
}
|
|
|
|
// PhysReg operands cannot have subregister indexes.
|
|
PhysReg = TRI->getSubReg(PhysReg, MO.getSubReg());
|
|
assert(PhysReg && "Invalid SubReg for physical register");
|
|
MO.setSubReg(0);
|
|
}
|
|
// Rewrite. Note we could have used MachineOperand::substPhysReg(), but
|
|
// we need the inlining here.
|
|
MO.setReg(PhysReg);
|
|
}
|
|
|
|
// Add any missing super-register kills after rewriting the whole
|
|
// instruction.
|
|
while (!SuperKills.empty())
|
|
MI->addRegisterKilled(SuperKills.pop_back_val(), TRI, true);
|
|
|
|
while (!SuperDeads.empty())
|
|
MI->addRegisterDead(SuperDeads.pop_back_val(), TRI, true);
|
|
|
|
while (!SuperDefs.empty())
|
|
MI->addRegisterDefined(SuperDefs.pop_back_val(), TRI);
|
|
|
|
DEBUG(dbgs() << "> " << *MI);
|
|
|
|
// Finally, remove any identity copies.
|
|
if (MI->isIdentityCopy()) {
|
|
++NumIdCopies;
|
|
if (MI->getNumOperands() == 2) {
|
|
DEBUG(dbgs() << "Deleting identity copy.\n");
|
|
if (Indexes)
|
|
Indexes->removeMachineInstrFromMaps(MI);
|
|
// It's safe to erase MI because MII has already been incremented.
|
|
MI->eraseFromParent();
|
|
} else {
|
|
// Transform identity copy to a KILL to deal with subregisters.
|
|
MI->setDesc(TII->get(TargetOpcode::KILL));
|
|
DEBUG(dbgs() << "Identity copy: " << *MI);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Tell MRI about physical registers in use.
|
|
if (NoReturnInsts.empty()) {
|
|
for (unsigned Reg = 1, RegE = TRI->getNumRegs(); Reg != RegE; ++Reg)
|
|
if (!MRI->reg_nodbg_empty(Reg))
|
|
MRI->setPhysRegUsed(Reg);
|
|
} else {
|
|
for (unsigned Reg = 1, RegE = TRI->getNumRegs(); Reg != RegE; ++Reg) {
|
|
if (MRI->reg_nodbg_empty(Reg))
|
|
continue;
|
|
// Check if this register has a use that will impact the rest of the
|
|
// code. Uses in debug and noreturn instructions do not impact the
|
|
// generated code.
|
|
for (MachineRegisterInfo::reg_nodbg_iterator It =
|
|
MRI->reg_nodbg_begin(Reg),
|
|
EndIt = MRI->reg_nodbg_end(); It != EndIt; ++It) {
|
|
if (!NoReturnInsts.count(&(*It))) {
|
|
MRI->setPhysRegUsed(Reg);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|