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//===-- RegAllocBase.cpp - Register Allocator Base Class ------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the RegAllocBase class which provides common functionality
// for LiveIntervalUnion-based register allocators.
//
//===----------------------------------------------------------------------===//
#include "RegAllocBase.h"
#include "Spiller.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/LiveIntervalAnalysis.h"
#include "llvm/CodeGen/LiveRangeEdit.h"
#include "llvm/CodeGen/LiveRegMatrix.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/VirtRegMap.h"
#include "llvm/Target/TargetRegisterInfo.h"
#ifndef NDEBUG
#include "llvm/ADT/SparseBitVector.h"
#endif
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/Timer.h"
using namespace llvm;
#define DEBUG_TYPE "regalloc"
STATISTIC(NumNewQueued , "Number of new live ranges queued");
// Temporary verification option until we can put verification inside
// MachineVerifier.
static cl::opt<bool, true>
VerifyRegAlloc("verify-regalloc", cl::location(RegAllocBase::VerifyEnabled),
cl::desc("Verify during register allocation"));
const char RegAllocBase::TimerGroupName[] = "Register Allocation";
bool RegAllocBase::VerifyEnabled = false;
//===----------------------------------------------------------------------===//
// RegAllocBase Implementation
//===----------------------------------------------------------------------===//
// Pin the vtable to this file.
void RegAllocBase::anchor() {}
void RegAllocBase::init(VirtRegMap &vrm,
LiveIntervals &lis,
LiveRegMatrix &mat) {
TRI = &vrm.getTargetRegInfo();
MRI = &vrm.getRegInfo();
VRM = &vrm;
LIS = &lis;
Matrix = &mat;
MRI->freezeReservedRegs(vrm.getMachineFunction());
RegClassInfo.runOnMachineFunction(vrm.getMachineFunction());
}
// Visit all the live registers. If they are already assigned to a physical
// register, unify them with the corresponding LiveIntervalUnion, otherwise push
// them on the priority queue for later assignment.
void RegAllocBase::seedLiveRegs() {
NamedRegionTimer T("Seed Live Regs", TimerGroupName, TimePassesIsEnabled);
for (unsigned i = 0, e = MRI->getNumVirtRegs(); i != e; ++i) {
unsigned Reg = TargetRegisterInfo::index2VirtReg(i);
if (MRI->reg_nodbg_empty(Reg))
continue;
enqueue(&LIS->getInterval(Reg));
}
}
// Top-level driver to manage the queue of unassigned VirtRegs and call the
// selectOrSplit implementation.
void RegAllocBase::allocatePhysRegs() {
seedLiveRegs();
// Continue assigning vregs one at a time to available physical registers.
while (LiveInterval *VirtReg = dequeue()) {
assert(!VRM->hasPhys(VirtReg->reg) && "Register already assigned");
// Unused registers can appear when the spiller coalesces snippets.
if (MRI->reg_nodbg_empty(VirtReg->reg)) {
DEBUG(dbgs() << "Dropping unused " << *VirtReg << '\n');
LIS->removeInterval(VirtReg->reg);
continue;
}
// Invalidate all interference queries, live ranges could have changed.
Matrix->invalidateVirtRegs();
// selectOrSplit requests the allocator to return an available physical
// register if possible and populate a list of new live intervals that
// result from splitting.
DEBUG(dbgs() << "\nselectOrSplit "
<< TRI->getRegClassName(MRI->getRegClass(VirtReg->reg))
<< ':' << *VirtReg << " w=" << VirtReg->weight << '\n');
typedef SmallVector<unsigned, 4> VirtRegVec;
VirtRegVec SplitVRegs;
unsigned AvailablePhysReg = selectOrSplit(*VirtReg, SplitVRegs);
if (AvailablePhysReg == ~0u) {
// selectOrSplit failed to find a register!
// Probably caused by an inline asm.
MachineInstr *MI = nullptr;
for (MachineRegisterInfo::reg_instr_iterator
I = MRI->reg_instr_begin(VirtReg->reg), E = MRI->reg_instr_end();
I != E; ) {
MachineInstr *TmpMI = &*(I++);
if (TmpMI->isInlineAsm()) {
MI = TmpMI;
break;
}
}
if (MI)
MI->emitError("inline assembly requires more registers than available");
else
report_fatal_error("ran out of registers during register allocation");
// Keep going after reporting the error.
VRM->assignVirt2Phys(VirtReg->reg,
RegClassInfo.getOrder(MRI->getRegClass(VirtReg->reg)).front());
continue;
}
if (AvailablePhysReg)
Matrix->assign(*VirtReg, AvailablePhysReg);
for (VirtRegVec::iterator I = SplitVRegs.begin(), E = SplitVRegs.end();
I != E; ++I) {
LiveInterval *SplitVirtReg = &LIS->getInterval(*I);
assert(!VRM->hasPhys(SplitVirtReg->reg) && "Register already assigned");
if (MRI->reg_nodbg_empty(SplitVirtReg->reg)) {
DEBUG(dbgs() << "not queueing unused " << *SplitVirtReg << '\n');
LIS->removeInterval(SplitVirtReg->reg);
continue;
}
DEBUG(dbgs() << "queuing new interval: " << *SplitVirtReg << "\n");
assert(TargetRegisterInfo::isVirtualRegister(SplitVirtReg->reg) &&
"expect split value in virtual register");
enqueue(SplitVirtReg);
++NumNewQueued;
}
}
}
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