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//===-- SelectionDAGISel.cpp - Implement the SelectionDAGISel class -------===//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// This implements the SelectionDAGISel class.
#define DEBUG_TYPE "isel"
#include "ScheduleDAGSDNodes.h"
#include "SelectionDAGBuilder.h"
#include "llvm/CodeGen/FunctionLoweringInfo.h"
#include "llvm/CodeGen/SelectionDAGISel.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/BranchProbabilityInfo.h"
#include "llvm/Analysis/DebugInfo.h"
#include "llvm/Constants.h"
#include "llvm/Function.h"
#include "llvm/InlineAsm.h"
#include "llvm/Instructions.h"
#include "llvm/Intrinsics.h"
#include "llvm/IntrinsicInst.h"
#include "llvm/LLVMContext.h"
#include "llvm/Module.h"
#include "llvm/CodeGen/FastISel.h"
#include "llvm/CodeGen/GCStrategy.h"
#include "llvm/CodeGen/GCMetadata.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/CodeGen/ScheduleHazardRecognizer.h"
#include "llvm/CodeGen/SchedulerRegistry.h"
#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetIntrinsicInfo.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetLibraryInfo.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/Timer.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/Statistic.h"
#include <algorithm>
using namespace llvm;
STATISTIC(NumFastIselFailures, "Number of instructions fast isel failed on");
STATISTIC(NumFastIselSuccess, "Number of instructions fast isel selected");
STATISTIC(NumFastIselBlocks, "Number of blocks selected entirely by fast isel");
STATISTIC(NumDAGBlocks, "Number of blocks selected using DAG");
STATISTIC(NumDAGIselRetries,"Number of times dag isel has to try another path");
#ifndef NDEBUG
static cl::opt<bool>
EnableFastISelVerbose2("fast-isel-verbose2", cl::Hidden,
cl::desc("Enable extra verbose messages in the \"fast\" "
"instruction selector"));
// Terminators
STATISTIC(NumFastIselFailRet,"Fast isel fails on Ret");
STATISTIC(NumFastIselFailBr,"Fast isel fails on Br");
STATISTIC(NumFastIselFailSwitch,"Fast isel fails on Switch");
STATISTIC(NumFastIselFailIndirectBr,"Fast isel fails on IndirectBr");
STATISTIC(NumFastIselFailInvoke,"Fast isel fails on Invoke");
STATISTIC(NumFastIselFailResume,"Fast isel fails on Resume");
STATISTIC(NumFastIselFailUnreachable,"Fast isel fails on Unreachable");
// Standard binary operators...
STATISTIC(NumFastIselFailAdd,"Fast isel fails on Add");
STATISTIC(NumFastIselFailFAdd,"Fast isel fails on FAdd");
STATISTIC(NumFastIselFailSub,"Fast isel fails on Sub");
STATISTIC(NumFastIselFailFSub,"Fast isel fails on FSub");
STATISTIC(NumFastIselFailMul,"Fast isel fails on Mul");
STATISTIC(NumFastIselFailFMul,"Fast isel fails on FMul");
STATISTIC(NumFastIselFailUDiv,"Fast isel fails on UDiv");
STATISTIC(NumFastIselFailSDiv,"Fast isel fails on SDiv");
STATISTIC(NumFastIselFailFDiv,"Fast isel fails on FDiv");
STATISTIC(NumFastIselFailURem,"Fast isel fails on URem");
STATISTIC(NumFastIselFailSRem,"Fast isel fails on SRem");
STATISTIC(NumFastIselFailFRem,"Fast isel fails on FRem");
// Logical operators...
STATISTIC(NumFastIselFailAnd,"Fast isel fails on And");
STATISTIC(NumFastIselFailOr,"Fast isel fails on Or");
STATISTIC(NumFastIselFailXor,"Fast isel fails on Xor");
// Memory instructions...
STATISTIC(NumFastIselFailAlloca,"Fast isel fails on Alloca");
STATISTIC(NumFastIselFailLoad,"Fast isel fails on Load");
STATISTIC(NumFastIselFailStore,"Fast isel fails on Store");
STATISTIC(NumFastIselFailAtomicCmpXchg,"Fast isel fails on AtomicCmpXchg");
STATISTIC(NumFastIselFailAtomicRMW,"Fast isel fails on AtomicRWM");
STATISTIC(NumFastIselFailFence,"Fast isel fails on Frence");
STATISTIC(NumFastIselFailGetElementPtr,"Fast isel fails on GetElementPtr");
// Convert instructions...
STATISTIC(NumFastIselFailTrunc,"Fast isel fails on Trunc");
STATISTIC(NumFastIselFailZExt,"Fast isel fails on ZExt");
STATISTIC(NumFastIselFailSExt,"Fast isel fails on SExt");
STATISTIC(NumFastIselFailFPTrunc,"Fast isel fails on FPTrunc");
STATISTIC(NumFastIselFailFPExt,"Fast isel fails on FPExt");
STATISTIC(NumFastIselFailFPToUI,"Fast isel fails on FPToUI");
STATISTIC(NumFastIselFailFPToSI,"Fast isel fails on FPToSI");
STATISTIC(NumFastIselFailUIToFP,"Fast isel fails on UIToFP");
STATISTIC(NumFastIselFailSIToFP,"Fast isel fails on SIToFP");
STATISTIC(NumFastIselFailIntToPtr,"Fast isel fails on IntToPtr");
STATISTIC(NumFastIselFailPtrToInt,"Fast isel fails on PtrToInt");
STATISTIC(NumFastIselFailBitCast,"Fast isel fails on BitCast");
// Other instructions...
STATISTIC(NumFastIselFailICmp,"Fast isel fails on ICmp");
STATISTIC(NumFastIselFailFCmp,"Fast isel fails on FCmp");
STATISTIC(NumFastIselFailPHI,"Fast isel fails on PHI");
STATISTIC(NumFastIselFailSelect,"Fast isel fails on Select");
STATISTIC(NumFastIselFailCall,"Fast isel fails on Call");
STATISTIC(NumFastIselFailShl,"Fast isel fails on Shl");
STATISTIC(NumFastIselFailLShr,"Fast isel fails on LShr");
STATISTIC(NumFastIselFailAShr,"Fast isel fails on AShr");
STATISTIC(NumFastIselFailVAArg,"Fast isel fails on VAArg");
STATISTIC(NumFastIselFailExtractElement,"Fast isel fails on ExtractElement");
STATISTIC(NumFastIselFailInsertElement,"Fast isel fails on InsertElement");
STATISTIC(NumFastIselFailShuffleVector,"Fast isel fails on ShuffleVector");
STATISTIC(NumFastIselFailExtractValue,"Fast isel fails on ExtractValue");
STATISTIC(NumFastIselFailInsertValue,"Fast isel fails on InsertValue");
STATISTIC(NumFastIselFailLandingPad,"Fast isel fails on LandingPad");
static cl::opt<bool>
EnableFastISelVerbose("fast-isel-verbose", cl::Hidden,
cl::desc("Enable verbose messages in the \"fast\" "
"instruction selector"));
static cl::opt<bool>
EnableFastISelAbort("fast-isel-abort", cl::Hidden,
cl::desc("Enable abort calls when \"fast\" instruction fails"));
static cl::opt<bool>
cl::desc("use Machine Branch Probability Info"),
cl::init(true), cl::Hidden);
#ifndef NDEBUG
static cl::opt<bool>
ViewDAGCombine1("view-dag-combine1-dags", cl::Hidden,
cl::desc("Pop up a window to show dags before the first "
"dag combine pass"));
static cl::opt<bool>
ViewLegalizeTypesDAGs("view-legalize-types-dags", cl::Hidden,
cl::desc("Pop up a window to show dags before legalize types"));
static cl::opt<bool>
ViewLegalizeDAGs("view-legalize-dags", cl::Hidden,
cl::desc("Pop up a window to show dags before legalize"));
static cl::opt<bool>
ViewDAGCombine2("view-dag-combine2-dags", cl::Hidden,
cl::desc("Pop up a window to show dags before the second "
"dag combine pass"));
static cl::opt<bool>
ViewDAGCombineLT("view-dag-combine-lt-dags", cl::Hidden,
cl::desc("Pop up a window to show dags before the post legalize types"
" dag combine pass"));
static cl::opt<bool>
ViewISelDAGs("view-isel-dags", cl::Hidden,
cl::desc("Pop up a window to show isel dags as they are selected"));
static cl::opt<bool>
ViewSchedDAGs("view-sched-dags", cl::Hidden,
cl::desc("Pop up a window to show sched dags as they are processed"));
static cl::opt<bool>
ViewSUnitDAGs("view-sunit-dags", cl::Hidden,
cl::desc("Pop up a window to show SUnit dags after they are processed"));
static const bool ViewDAGCombine1 = false,
ViewLegalizeTypesDAGs = false, ViewLegalizeDAGs = false,
ViewDAGCombine2 = false,
ViewDAGCombineLT = false,
ViewISelDAGs = false, ViewSchedDAGs = false,
ViewSUnitDAGs = false;
/// RegisterScheduler class - Track the registration of instruction schedulers.
MachinePassRegistry RegisterScheduler::Registry;
/// ISHeuristic command line option for instruction schedulers.
static cl::opt<RegisterScheduler::FunctionPassCtor, false,
RegisterPassParser<RegisterScheduler> >
cl::desc("Instruction schedulers available (before register"
" allocation):"));
static RegisterScheduler
defaultListDAGScheduler("default", "Best scheduler for the target",
namespace llvm {
/// createDefaultScheduler - This creates an instruction scheduler appropriate
/// for the target.
ScheduleDAGSDNodes* createDefaultScheduler(SelectionDAGISel *IS,
CodeGenOpt::Level OptLevel) {
const TargetLowering &TLI = IS->getTargetLowering();
if (OptLevel == CodeGenOpt::None ||
TLI.getSchedulingPreference() == Sched::Source)
return createSourceListDAGScheduler(IS, OptLevel);
if (TLI.getSchedulingPreference() == Sched::RegPressure)
return createBURRListDAGScheduler(IS, OptLevel);
if (TLI.getSchedulingPreference() == Sched::Hybrid)
return createHybridListDAGScheduler(IS, OptLevel);
if (TLI.getSchedulingPreference() == Sched::VLIW)
return createVLIWDAGScheduler(IS, OptLevel);
assert(TLI.getSchedulingPreference() == Sched::ILP &&
"Unknown sched type!");
return createILPListDAGScheduler(IS, OptLevel);
// EmitInstrWithCustomInserter - This method should be implemented by targets
// that mark instructions with the 'usesCustomInserter' flag. These
// instructions are special in various ways, which require special support to
// insert. The specified MachineInstr is created but not inserted into any
// basic blocks, and this method is called to expand it into a sequence of
// instructions, potentially also creating new basic blocks and control flow.
// When new basic blocks are inserted and the edges from MBB to its successors
// are modified, the method should insert pairs of <OldSucc, NewSucc> into the
// DenseMap.
MachineBasicBlock *
TargetLowering::EmitInstrWithCustomInserter(MachineInstr *MI,
MachineBasicBlock *MBB) const {
#ifndef NDEBUG
dbgs() << "If a target marks an instruction with "
"'usesCustomInserter', it must implement "
void TargetLowering::AdjustInstrPostInstrSelection(MachineInstr *MI,
SDNode *Node) const {
assert(!MI->hasPostISelHook() &&
"If a target marks an instruction with 'hasPostISelHook', "
"it must implement TargetLowering::AdjustInstrPostInstrSelection!");
// SelectionDAGISel code
void SelectionDAGISel::ISelUpdater::anchor() { }
SelectionDAGISel::SelectionDAGISel(const TargetMachine &tm,
CodeGenOpt::Level OL) :
MachineFunctionPass(ID), TM(tm), TLI(*tm.getTargetLowering()),
FuncInfo(new FunctionLoweringInfo(TLI)),
CurDAG(new SelectionDAG(tm, OL)),
SDB(new SelectionDAGBuilder(*CurDAG, *FuncInfo, OL)),
DAGSize(0) {
SelectionDAGISel::~SelectionDAGISel() {
delete SDB;
delete CurDAG;
delete FuncInfo;
void SelectionDAGISel::getAnalysisUsage(AnalysisUsage &AU) const {
if (UseMBPI && OptLevel != CodeGenOpt::None)
/// SplitCriticalSideEffectEdges - Look for critical edges with a PHI value that
/// may trap on it. In this case we have to split the edge so that the path
/// through the predecessor block that doesn't go to the phi block doesn't
/// execute the possibly trapping instruction.
/// This is required for correctness, so it must be done at -O0.
static void SplitCriticalSideEffectEdges(Function &Fn, Pass *SDISel) {
// Loop for blocks with phi nodes.
for (Function::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB) {
PHINode *PN = dyn_cast<PHINode>(BB->begin());
if (PN == 0) continue;
// For each block with a PHI node, check to see if any of the input values
// are potentially trapping constant expressions. Constant expressions are
// the only potentially trapping value that can occur as the argument to a
// PHI.
for (BasicBlock::iterator I = BB->begin(); (PN = dyn_cast<PHINode>(I)); ++I)
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
ConstantExpr *CE = dyn_cast<ConstantExpr>(PN->getIncomingValue(i));
if (CE == 0 || !CE->canTrap()) continue;
// The only case we have to worry about is when the edge is critical.
// Since this block has a PHI Node, we assume it has multiple input
// edges: check to see if the pred has multiple successors.
BasicBlock *Pred = PN->getIncomingBlock(i);
if (Pred->getTerminator()->getNumSuccessors() == 1)
// Okay, we have to split this edge.
GetSuccessorNumber(Pred, BB), SDISel, true);
goto ReprocessBlock;
bool SelectionDAGISel::runOnMachineFunction(MachineFunction &mf) {
// Do some sanity-checking on the command-line options.
assert((!EnableFastISelVerbose || TM.Options.EnableFastISel) &&
"-fast-isel-verbose requires -fast-isel");
assert((!EnableFastISelAbort || TM.Options.EnableFastISel) &&
"-fast-isel-abort requires -fast-isel");
const Function &Fn = *mf.getFunction();
const TargetInstrInfo &TII = *TM.getInstrInfo();
const TargetRegisterInfo &TRI = *TM.getRegisterInfo();
MF = &mf;
RegInfo = &MF->getRegInfo();
AA = &getAnalysis<AliasAnalysis>();
LibInfo = &getAnalysis<TargetLibraryInfo>();
GFI = Fn.hasGC() ? &getAnalysis<GCModuleInfo>().getFunctionInfo(Fn) : 0;
DEBUG(dbgs() << "\n\n\n=== " << Fn.getName() << "\n");
SplitCriticalSideEffectEdges(const_cast<Function&>(Fn), this);
FuncInfo->set(Fn, *MF);
if (UseMBPI && OptLevel != CodeGenOpt::None)
FuncInfo->BPI = &getAnalysis<BranchProbabilityInfo>();
FuncInfo->BPI = 0;
SDB->init(GFI, *AA, LibInfo);
// If the first basic block in the function has live ins that need to be
// copied into vregs, emit the copies into the top of the block before
// emitting the code for the block.
MachineBasicBlock *EntryMBB = MF->begin();
RegInfo->EmitLiveInCopies(EntryMBB, TRI, TII);
DenseMap<unsigned, unsigned> LiveInMap;
if (!FuncInfo->ArgDbgValues.empty())
for (MachineRegisterInfo::livein_iterator LI = RegInfo->livein_begin(),
E = RegInfo->livein_end(); LI != E; ++LI)
if (LI->second)
LiveInMap.insert(std::make_pair(LI->first, LI->second));
// Insert DBG_VALUE instructions for function arguments to the entry block.
for (unsigned i = 0, e = FuncInfo->ArgDbgValues.size(); i != e; ++i) {
MachineInstr *MI = FuncInfo->ArgDbgValues[e-i-1];
unsigned Reg = MI->getOperand(0).getReg();
if (TargetRegisterInfo::isPhysicalRegister(Reg))
EntryMBB->insert(EntryMBB->begin(), MI);
else {
MachineInstr *Def = RegInfo->getVRegDef(Reg);
MachineBasicBlock::iterator InsertPos = Def;
// FIXME: VR def may not be in entry block.
Def->getParent()->insert(llvm::next(InsertPos), MI);
// If Reg is live-in then update debug info to track its copy in a vreg.
DenseMap<unsigned, unsigned>::iterator LDI = LiveInMap.find(Reg);
if (LDI != LiveInMap.end()) {
MachineInstr *Def = RegInfo->getVRegDef(LDI->second);
MachineBasicBlock::iterator InsertPos = Def;
const MDNode *Variable =
unsigned Offset = MI->getOperand(1).getImm();
// Def is never a terminator here, so it is ok to increment InsertPos.
BuildMI(*EntryMBB, ++InsertPos, MI->getDebugLoc(),
.addReg(LDI->second, RegState::Debug)
// If this vreg is directly copied into an exported register then
// that COPY instructions also need DBG_VALUE, if it is the only
// user of LDI->second.
MachineInstr *CopyUseMI = NULL;
for (MachineRegisterInfo::use_iterator
UI = RegInfo->use_begin(LDI->second);
MachineInstr *UseMI = UI.skipInstruction();) {
if (UseMI->isDebugValue()) continue;
if (UseMI->isCopy() && !CopyUseMI && UseMI->getParent() == EntryMBB) {
CopyUseMI = UseMI; continue;
// Otherwise this is another use or second copy use.
CopyUseMI = NULL; break;
if (CopyUseMI) {
MachineInstr *NewMI =
BuildMI(*MF, CopyUseMI->getDebugLoc(),
.addReg(CopyUseMI->getOperand(0).getReg(), RegState::Debug)
MachineBasicBlock::iterator Pos = CopyUseMI;
EntryMBB->insertAfter(Pos, NewMI);
// Determine if there are any calls in this machine function.
MachineFrameInfo *MFI = MF->getFrameInfo();
if (!MFI->hasCalls()) {
for (MachineFunction::const_iterator
I = MF->begin(), E = MF->end(); I != E; ++I) {
const MachineBasicBlock *MBB = I;
for (MachineBasicBlock::const_iterator
II = MBB->begin(), IE = MBB->end(); II != IE; ++II) {
const MCInstrDesc &MCID = TM.getInstrInfo()->get(II->getOpcode());
if ((MCID.isCall() && !MCID.isReturn()) ||
II->isStackAligningInlineAsm()) {
goto done;
// Determine if there is a call to setjmp in the machine function.
// Replace forward-declared registers with the registers containing
// the desired value.
MachineRegisterInfo &MRI = MF->getRegInfo();
for (DenseMap<unsigned, unsigned>::iterator
I = FuncInfo->RegFixups.begin(), E = FuncInfo->RegFixups.end();
I != E; ++I) {
unsigned From = I->first;
unsigned To = I->second;
// If To is also scheduled to be replaced, find what its ultimate
// replacement is.
for (;;) {
DenseMap<unsigned, unsigned>::iterator J =
if (J == E) break;
To = J->second;
// Replace it.
MRI.replaceRegWith(From, To);
// Release function-specific state. SDB and CurDAG are already cleared
// at this point.
return true;
void SelectionDAGISel::SelectBasicBlock(BasicBlock::const_iterator Begin,
BasicBlock::const_iterator End,
bool &HadTailCall) {
// Lower all of the non-terminator instructions. If a call is emitted
// as a tail call, cease emitting nodes for this block. Terminators
// are handled below.
for (BasicBlock::const_iterator I = Begin; I != End && !SDB->HasTailCall; ++I)
// Make sure the root of the DAG is up-to-date.
HadTailCall = SDB->HasTailCall;
// Final step, emit the lowered DAG as machine code.
void SelectionDAGISel::ComputeLiveOutVRegInfo() {
SmallPtrSet<SDNode*, 128> VisitedNodes;
SmallVector<SDNode*, 128> Worklist;
APInt KnownZero;
APInt KnownOne;
do {
SDNode *N = Worklist.pop_back_val();
// If we've already seen this node, ignore it.
if (!VisitedNodes.insert(N))
// Otherwise, add all chain operands to the worklist.
for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
if (N->getOperand(i).getValueType() == MVT::Other)
// If this is a CopyToReg with a vreg dest, process it.
if (N->getOpcode() != ISD::CopyToReg)
unsigned DestReg = cast<RegisterSDNode>(N->getOperand(1))->getReg();
if (!TargetRegisterInfo::isVirtualRegister(DestReg))
// Ignore non-scalar or non-integer values.
SDValue Src = N->getOperand(2);
EVT SrcVT = Src.getValueType();
if (!SrcVT.isInteger() || SrcVT.isVector())
unsigned NumSignBits = CurDAG->ComputeNumSignBits(Src);
CurDAG->ComputeMaskedBits(Src, KnownZero, KnownOne);
FuncInfo->AddLiveOutRegInfo(DestReg, NumSignBits, KnownZero, KnownOne);
} while (!Worklist.empty());
void SelectionDAGISel::CodeGenAndEmitDAG() {
std::string GroupName;
if (TimePassesIsEnabled)
GroupName = "Instruction Selection and Scheduling";
std::string BlockName;
int BlockNumber = -1;
#ifdef NDEBUG
if (ViewDAGCombine1 || ViewLegalizeTypesDAGs || ViewLegalizeDAGs ||
ViewDAGCombine2 || ViewDAGCombineLT || ViewISelDAGs || ViewSchedDAGs ||
BlockNumber = FuncInfo->MBB->getNumber();
BlockName = MF->getFunction()->getName().str() + ":" +
DEBUG(dbgs() << "Initial selection DAG: BB#" << BlockNumber
<< " '" << BlockName << "'\n"; CurDAG->dump());
if (ViewDAGCombine1) CurDAG->viewGraph("dag-combine1 input for " + BlockName);
// Run the DAG combiner in pre-legalize mode.
NamedRegionTimer T("DAG Combining 1", GroupName, TimePassesIsEnabled);
CurDAG->Combine(BeforeLegalizeTypes, *AA, OptLevel);
DEBUG(dbgs() << "Optimized lowered selection DAG: BB#" << BlockNumber
<< " '" << BlockName << "'\n"; CurDAG->dump());
// Second step, hack on the DAG until it only uses operations and types that
// the target supports.
if (ViewLegalizeTypesDAGs) CurDAG->viewGraph("legalize-types input for " +
bool Changed;
NamedRegionTimer T("Type Legalization", GroupName, TimePassesIsEnabled);
Changed = CurDAG->LegalizeTypes();
DEBUG(dbgs() << "Type-legalized selection DAG: BB#" << BlockNumber
<< " '" << BlockName << "'\n"; CurDAG->dump());
if (Changed) {
if (ViewDAGCombineLT)
CurDAG->viewGraph("dag-combine-lt input for " + BlockName);
// Run the DAG combiner in post-type-legalize mode.
NamedRegionTimer T("DAG Combining after legalize types", GroupName,
CurDAG->Combine(AfterLegalizeTypes, *AA, OptLevel);
DEBUG(dbgs() << "Optimized type-legalized selection DAG: BB#" << BlockNumber
<< " '" << BlockName << "'\n"; CurDAG->dump());
NamedRegionTimer T("Vector Legalization", GroupName, TimePassesIsEnabled);
Changed = CurDAG->LegalizeVectors();
if (Changed) {
NamedRegionTimer T("Type Legalization 2", GroupName, TimePassesIsEnabled);
if (ViewDAGCombineLT)
CurDAG->viewGraph("dag-combine-lv input for " + BlockName);
// Run the DAG combiner in post-type-legalize mode.
NamedRegionTimer T("DAG Combining after legalize vectors", GroupName,
CurDAG->Combine(AfterLegalizeVectorOps, *AA, OptLevel);
DEBUG(dbgs() << "Optimized vector-legalized selection DAG: BB#"
<< BlockNumber << " '" << BlockName << "'\n"; CurDAG->dump());
if (ViewLegalizeDAGs) CurDAG->viewGraph("legalize input for " + BlockName);
NamedRegionTimer T("DAG Legalization", GroupName, TimePassesIsEnabled);
DEBUG(dbgs() << "Legalized selection DAG: BB#" << BlockNumber
<< " '" << BlockName << "'\n"; CurDAG->dump());
if (ViewDAGCombine2) CurDAG->viewGraph("dag-combine2 input for " + BlockName);
// Run the DAG combiner in post-legalize mode.
NamedRegionTimer T("DAG Combining 2", GroupName, TimePassesIsEnabled);
CurDAG->Combine(AfterLegalizeDAG, *AA, OptLevel);
DEBUG(dbgs() << "Optimized legalized selection DAG: BB#" << BlockNumber
<< " '" << BlockName << "'\n"; CurDAG->dump());
if (OptLevel != CodeGenOpt::None)
if (ViewISelDAGs) CurDAG->viewGraph("isel input for " + BlockName);
// Third, instruction select all of the operations to machine code, adding the
// code to the MachineBasicBlock.
NamedRegionTimer T("Instruction Selection", GroupName, TimePassesIsEnabled);
DEBUG(dbgs() << "Selected selection DAG: BB#" << BlockNumber
<< " '" << BlockName << "'\n"; CurDAG->dump());
if (ViewSchedDAGs) CurDAG->viewGraph("scheduler input for " + BlockName);
// Schedule machine code.
ScheduleDAGSDNodes *Scheduler = CreateScheduler();
NamedRegionTimer T("Instruction Scheduling", GroupName,
Scheduler->Run(CurDAG, FuncInfo->MBB);
if (ViewSUnitDAGs) Scheduler->viewGraph();
// Emit machine code to BB. This can change 'BB' to the last block being
// inserted into.
MachineBasicBlock *FirstMBB = FuncInfo->MBB, *LastMBB;
NamedRegionTimer T("Instruction Creation", GroupName, TimePassesIsEnabled);
// FuncInfo->InsertPt is passed by reference and set to the end of the
// scheduled instructions.
LastMBB = FuncInfo->MBB = Scheduler->EmitSchedule(FuncInfo->InsertPt);
// If the block was split, make sure we update any references that are used to
// update PHI nodes later on.
if (FirstMBB != LastMBB)
SDB->UpdateSplitBlock(FirstMBB, LastMBB);
// Free the scheduler state.
NamedRegionTimer T("Instruction Scheduling Cleanup", GroupName,
delete Scheduler;
// Free the SelectionDAG state, now that we're finished with it.
void SelectionDAGISel::DoInstructionSelection() {
DEBUG(errs() << "===== Instruction selection begins: BB#"
<< FuncInfo->MBB->getNumber()
<< " '" << FuncInfo->MBB->getName() << "'\n");
// Select target instructions for the DAG.
// Number all nodes with a topological order and set DAGSize.
DAGSize = CurDAG->AssignTopologicalOrder();
// Create a dummy node (which is not added to allnodes), that adds
// a reference to the root node, preventing it from being deleted,
// and tracking any changes of the root.
HandleSDNode Dummy(CurDAG->getRoot());
ISelPosition = SelectionDAG::allnodes_iterator(CurDAG->getRoot().getNode());
// The AllNodes list is now topological-sorted. Visit the
// nodes by starting at the end of the list (the root of the
// graph) and preceding back toward the beginning (the entry
// node).
while (ISelPosition != CurDAG->allnodes_begin()) {
SDNode *Node = --ISelPosition;
// Skip dead nodes. DAGCombiner is expected to eliminate all dead nodes,
// but there are currently some corner cases that it misses. Also, this
// makes it theoretically possible to disable the DAGCombiner.
if (Node->use_empty())
SDNode *ResNode = Select(Node);
// FIXME: This is pretty gross. 'Select' should be changed to not return
// anything at all and this code should be nuked with a tactical strike.
// If node should not be replaced, continue with the next one.
if (ResNode == Node || Node->getOpcode() == ISD::DELETED_NODE)
// Replace node.
if (ResNode)
ReplaceUses(Node, ResNode);
// If after the replacement this node is not used any more,
// remove this dead node.
if (Node->use_empty()) { // Don't delete EntryToken, etc.
ISelUpdater ISU(ISelPosition);
CurDAG->RemoveDeadNode(Node, &ISU);
DEBUG(errs() << "===== Instruction selection ends:\n");
/// PrepareEHLandingPad - Emit an EH_LABEL, set up live-in registers, and
/// do other setup for EH landing-pad blocks.
void SelectionDAGISel::PrepareEHLandingPad() {
MachineBasicBlock *MBB = FuncInfo->MBB;
// Add a label to mark the beginning of the landing pad. Deletion of the
// landing pad can thus be detected via the MachineModuleInfo.
MCSymbol *Label = MF->getMMI().addLandingPad(MBB);
// Assign the call site to the landing pad's begin label.
MF->getMMI().setCallSiteLandingPad(Label, SDB->LPadToCallSiteMap[MBB]);
const MCInstrDesc &II = TM.getInstrInfo()->get(TargetOpcode::EH_LABEL);
BuildMI(*MBB, FuncInfo->InsertPt, SDB->getCurDebugLoc(), II)
// Mark exception register as live in.
unsigned Reg = TLI.getExceptionPointerRegister();
if (Reg) MBB->addLiveIn(Reg);
// Mark exception selector register as live in.
Reg = TLI.getExceptionSelectorRegister();
if (Reg) MBB->addLiveIn(Reg);
/// TryToFoldFastISelLoad - We're checking to see if we can fold the specified
/// load into the specified FoldInst. Note that we could have a sequence where
/// multiple LLVM IR instructions are folded into the same machineinstr. For
/// example we could have:
/// A: x = load i32 *P
/// B: y = icmp A, 42
/// C: br y, ...
/// In this scenario, LI is "A", and FoldInst is "C". We know about "B" (and
/// any other folded instructions) because it is between A and C.
/// If we succeed in folding the load into the operation, return true.
bool SelectionDAGISel::TryToFoldFastISelLoad(const LoadInst *LI,
const Instruction *FoldInst,
FastISel *FastIS) {
// We know that the load has a single use, but don't know what it is. If it
// isn't one of the folded instructions, then we can't succeed here. Handle
// this by scanning the single-use users of the load until we get to FoldInst.
unsigned MaxUsers = 6; // Don't scan down huge single-use chains of instrs.
const Instruction *TheUser = LI->use_back();
while (TheUser != FoldInst && // Scan up until we find FoldInst.
// Stay in the right block.
TheUser->getParent() == FoldInst->getParent() &&
--MaxUsers) { // Don't scan too far.
// If there are multiple or no uses of this instruction, then bail out.
if (!TheUser->hasOneUse())
return false;
TheUser = TheUser->use_back();
// If we didn't find the fold instruction, then we failed to collapse the
// sequence.
if (TheUser != FoldInst)
return false;
// Don't try to fold volatile loads. Target has to deal with alignment
// constraints.
if (LI->isVolatile()) return false;
// Figure out which vreg this is going into. If there is no assigned vreg yet
// then there actually was no reference to it. Perhaps the load is referenced
// by a dead instruction.
unsigned LoadReg = FastIS->getRegForValue(LI);
if (LoadReg == 0)
return false;
// Check to see what the uses of this vreg are. If it has no uses, or more
// than one use (at the machine instr level) then we can't fold it.
MachineRegisterInfo::reg_iterator RI = RegInfo->reg_begin(LoadReg);
if (RI == RegInfo->reg_end())
return false;
// See if there is exactly one use of the vreg. If there are multiple uses,
// then the instruction got lowered to multiple machine instructions or the
// use of the loaded value ended up being multiple operands of the result, in
// either case, we can't fold this.
MachineRegisterInfo::reg_iterator PostRI = RI; ++PostRI;
if (PostRI != RegInfo->reg_end())
return false;
assert(RI.getOperand().isUse() &&
"The only use of the vreg must be a use, we haven't emitted the def!");
MachineInstr *User = &*RI;
// Set the insertion point properly. Folding the load can cause generation of
// other random instructions (like sign extends) for addressing modes, make
// sure they get inserted in a logical place before the new instruction.
FuncInfo->InsertPt = User;
FuncInfo->MBB = User->getParent();
// Ask the target to try folding the load.
return FastIS->TryToFoldLoad(User, RI.getOperandNo(), LI);
/// isFoldedOrDeadInstruction - Return true if the specified instruction is
/// side-effect free and is either dead or folded into a generated instruction.
/// Return false if it needs to be emitted.
static bool isFoldedOrDeadInstruction(const Instruction *I,
FunctionLoweringInfo *FuncInfo) {
return !I->mayWriteToMemory() && // Side-effecting instructions aren't folded.
!isa<TerminatorInst>(I) && // Terminators aren't folded.
!isa<DbgInfoIntrinsic>(I) && // Debug instructions aren't folded.
!isa<LandingPadInst>(I) && // Landingpad instructions aren't folded.
!FuncInfo->isExportedInst(I); // Exported instrs must be computed.
#ifndef NDEBUG
// Collect per Instruction statistics for fast-isel misses. Only those
// instructions that cause the bail are accounted for. It does not account for
// instructions higher in the block. Thus, summing the per instructions stats
// will not add up to what is reported by NumFastIselFailures.
static void collectFailStats(const Instruction *I) {
switch (I->getOpcode()) {
default: assert (0 && "<Invalid operator> ");
// Terminators
case Instruction::Ret: NumFastIselFailRet++; return;
case Instruction::Br: NumFastIselFailBr++; return;
case Instruction::Switch: NumFastIselFailSwitch++; return;
case Instruction::IndirectBr: NumFastIselFailIndirectBr++; return;
case Instruction::Invoke: NumFastIselFailInvoke++; return;
case Instruction::Resume: NumFastIselFailResume++; return;
case Instruction::Unreachable: NumFastIselFailUnreachable++; return;
// Standard binary operators...
case Instruction::Add: NumFastIselFailAdd++; return;
case Instruction::FAdd: NumFastIselFailFAdd++; return;
case Instruction::Sub: NumFastIselFailSub++; return;
case Instruction::FSub: NumFastIselFailFSub++; return;
case Instruction::Mul: NumFastIselFailMul++; return;
case Instruction::FMul: NumFastIselFailFMul++; return;
case Instruction::UDiv: NumFastIselFailUDiv++; return;
case Instruction::SDiv: NumFastIselFailSDiv++; return;
case Instruction::FDiv: NumFastIselFailFDiv++; return;
case Instruction::URem: NumFastIselFailURem++; return;
case Instruction::SRem: NumFastIselFailSRem++; return;
case Instruction::FRem: NumFastIselFailFRem++; return;
// Logical operators...
case Instruction::And: NumFastIselFailAnd++; return;
case Instruction::Or: NumFastIselFailOr++; return;
case Instruction::Xor: NumFastIselFailXor++; return;
// Memory instructions...
case Instruction::Alloca: NumFastIselFailAlloca++; return;
case Instruction::Load: NumFastIselFailLoad++; return;
case Instruction::Store: NumFastIselFailStore++; return;
case Instruction::AtomicCmpXchg: NumFastIselFailAtomicCmpXchg++; return;
case Instruction::AtomicRMW: NumFastIselFailAtomicRMW++; return;
case Instruction::Fence: NumFastIselFailFence++; return;
case Instruction::GetElementPtr: NumFastIselFailGetElementPtr++; return;
// Convert instructions...
case Instruction::Trunc: NumFastIselFailTrunc++; return;
case Instruction::ZExt: NumFastIselFailZExt++; return;
case Instruction::SExt: NumFastIselFailSExt++; return;
case Instruction::FPTrunc: NumFastIselFailFPTrunc++; return;
case Instruction::FPExt: NumFastIselFailFPExt++; return;
case Instruction::FPToUI: NumFastIselFailFPToUI++; return;
case Instruction::FPToSI: NumFastIselFailFPToSI++; return;
case Instruction::UIToFP: NumFastIselFailUIToFP++; return;
case Instruction::SIToFP: NumFastIselFailSIToFP++; return;
case Instruction::IntToPtr: NumFastIselFailIntToPtr++; return;
case Instruction::PtrToInt: NumFastIselFailPtrToInt++; return;
case Instruction::BitCast: NumFastIselFailBitCast++; return;
// Other instructions...
case Instruction::ICmp: NumFastIselFailICmp++; return;
case Instruction::FCmp: NumFastIselFailFCmp++; return;
case Instruction::PHI: NumFastIselFailPHI++; return;
case Instruction::Select: NumFastIselFailSelect++; return;
case Instruction::Call: NumFastIselFailCall++; return;
case Instruction::Shl: NumFastIselFailShl++; return;
case Instruction::LShr: NumFastIselFailLShr++; return;
case Instruction::AShr: NumFastIselFailAShr++; return;
case Instruction::VAArg: NumFastIselFailVAArg++; return;
case Instruction::ExtractElement: NumFastIselFailExtractElement++; return;
case Instruction::InsertElement: NumFastIselFailInsertElement++; return;
case Instruction::ShuffleVector: NumFastIselFailShuffleVector++; return;
case Instruction::ExtractValue: NumFastIselFailExtractValue++; return;
case Instruction::InsertValue: NumFastIselFailInsertValue++; return;
case Instruction::LandingPad: NumFastIselFailLandingPad++; return;
void SelectionDAGISel::SelectAllBasicBlocks(const Function &Fn) {
// Initialize the Fast-ISel state, if needed.
FastISel *FastIS = 0;
if (TM.Options.EnableFastISel)
FastIS = TLI.createFastISel(*FuncInfo);
// Iterate over all basic blocks in the function.
ReversePostOrderTraversal<const Function*> RPOT(&Fn);
for (ReversePostOrderTraversal<const Function*>::rpo_iterator
I = RPOT.begin(), E = RPOT.end(); I != E; ++I) {
const BasicBlock *LLVMBB = *I;
if (OptLevel != CodeGenOpt::None) {
bool AllPredsVisited = true;
for (const_pred_iterator PI = pred_begin(LLVMBB), PE = pred_end(LLVMBB);
PI != PE; ++PI) {
if (!FuncInfo->VisitedBBs.count(*PI)) {
AllPredsVisited = false;
if (AllPredsVisited) {
for (BasicBlock::const_iterator I = LLVMBB->begin();
isa<PHINode>(I); ++I)
} else {
for (BasicBlock::const_iterator I = LLVMBB->begin();
isa<PHINode>(I); ++I)
FuncInfo->MBB = FuncInfo->MBBMap[LLVMBB];
FuncInfo->InsertPt = FuncInfo->MBB->getFirstNonPHI();
BasicBlock::const_iterator const Begin = LLVMBB->getFirstNonPHI();
BasicBlock::const_iterator const End = LLVMBB->end();
BasicBlock::const_iterator BI = End;
FuncInfo->InsertPt = FuncInfo->MBB->getFirstNonPHI();
// Setup an EH landing-pad block.
if (FuncInfo->MBB->isLandingPad())
// Lower any arguments needed in this block if this is the entry block.
if (LLVMBB == &Fn.getEntryBlock())
// Before doing SelectionDAG ISel, see if FastISel has been requested.
if (FastIS) {
// Emit code for any incoming arguments. This must happen before
// beginning FastISel on the entry block.
if (LLVMBB == &Fn.getEntryBlock()) {
// If we inserted any instructions at the beginning, make a note of
// where they are, so we can be sure to emit subsequent instructions
// after them.
if (FuncInfo->InsertPt != FuncInfo->MBB->begin())
unsigned NumFastIselRemaining = std::distance(Begin, End);
// Do FastISel on as many instructions as possible.
for (; BI != Begin; --BI) {
const Instruction *Inst = llvm::prior(BI);
// If we no longer require this instruction, skip it.
if (isFoldedOrDeadInstruction(Inst, FuncInfo)) {
// Bottom-up: reset the insert pos at the top, after any local-value
// instructions.
// Try to select the instruction with FastISel.
if (FastIS->SelectInstruction(Inst)) {
// If fast isel succeeded, skip over all the folded instructions, and
// then see if there is a load right before the selected instructions.
// Try to fold the load if so.
const Instruction *BeforeInst = Inst;
while (BeforeInst != Begin) {
BeforeInst = llvm::prior(BasicBlock::const_iterator(BeforeInst));
if (!isFoldedOrDeadInstruction(BeforeInst, FuncInfo))
if (BeforeInst != Inst && isa<LoadInst>(BeforeInst) &&
BeforeInst->hasOneUse() &&
TryToFoldFastISelLoad(cast<LoadInst>(BeforeInst), Inst, FastIS)) {
// If we succeeded, don't re-select the load.
BI = llvm::next(BasicBlock::const_iterator(BeforeInst));
#ifndef NDEBUG
if (EnableFastISelVerbose2)
// Then handle certain instructions as single-LLVM-Instruction blocks.
if (isa<CallInst>(Inst)) {
if (EnableFastISelVerbose || EnableFastISelAbort) {
dbgs() << "FastISel missed call: ";
if (!Inst->getType()->isVoidTy() && !Inst->use_empty()) {
unsigned &R = FuncInfo->ValueMap[Inst];
if (!R)
R = FuncInfo->CreateRegs(Inst->getType());
bool HadTailCall = false;
SelectBasicBlock(Inst, BI, HadTailCall);
// Recompute NumFastIselRemaining as Selection DAG instruction
// selection may have handled the call, input args, etc.
unsigned RemainingNow = std::distance(Begin, BI);
NumFastIselFailures += NumFastIselRemaining - RemainingNow;
// If the call was emitted as a tail call, we're done with the block.
if (HadTailCall) {
NumFastIselRemaining = RemainingNow;
if (isa<TerminatorInst>(Inst) && !isa<BranchInst>(Inst)) {
// Don't abort, and use a different message for terminator misses.
NumFastIselFailures += NumFastIselRemaining;
if (EnableFastISelVerbose || EnableFastISelAbort) {
dbgs() << "FastISel missed terminator: ";
} else {
NumFastIselFailures += NumFastIselRemaining;
if (EnableFastISelVerbose || EnableFastISelAbort) {
dbgs() << "FastISel miss: ";
if (EnableFastISelAbort)
// The "fast" selector couldn't handle something and bailed.
// For the purpose of debugging, just abort.
llvm_unreachable("FastISel didn't select the entire block");
if (Begin != BI)
if (Begin != BI) {
// Run SelectionDAG instruction selection on the remainder of the block
// not handled by FastISel. If FastISel is not run, this is the entire
// block.
bool HadTailCall;
SelectBasicBlock(Begin, BI, HadTailCall);
delete FastIS;
SelectionDAGISel::FinishBasicBlock() {
DEBUG(dbgs() << "Total amount of phi nodes to update: "
<< FuncInfo->PHINodesToUpdate.size() << "\n";
for (unsigned i = 0, e = FuncInfo->PHINodesToUpdate.size(); i != e; ++i)
dbgs() << "Node " << i << " : ("
<< FuncInfo->PHINodesToUpdate[i].first
<< ", " << FuncInfo->PHINodesToUpdate[i].second << ")\n");
// Next, now that we know what the last MBB the LLVM BB expanded is, update
// PHI nodes in successors.
if (SDB->SwitchCases.empty() &&
SDB->JTCases.empty() &&
SDB->BitTestCases.empty()) {
for (unsigned i = 0, e = FuncInfo->PHINodesToUpdate.size(); i != e; ++i) {
MachineInstr *PHI = FuncInfo->PHINodesToUpdate[i].first;
assert(PHI->isPHI() &&
"This is not a machine PHI node that we are updating!");
if (!FuncInfo->MBB->isSuccessor(PHI->getParent()))
MachineOperand::CreateReg(FuncInfo->PHINodesToUpdate[i].second, false));
for (unsigned i = 0, e = SDB->BitTestCases.size(); i != e; ++i) {
// Lower header first, if it wasn't already lowered
if (!SDB->BitTestCases[i].Emitted) {
// Set the current basic block to the mbb we wish to insert the code into
FuncInfo->MBB = SDB->BitTestCases[i].Parent;
FuncInfo->InsertPt = FuncInfo->MBB->end();
// Emit the code
SDB->visitBitTestHeader(SDB->BitTestCases[i], FuncInfo->MBB);
for (unsigned j = 0, ej = SDB->BitTestCases[i].Cases.size(); j != ej; ++j) {
// Set the current basic block to the mbb we wish to insert the code into
FuncInfo->MBB = SDB->BitTestCases[i].Cases[j].ThisBB;
FuncInfo->InsertPt = FuncInfo->MBB->end();
// Emit the code
if (j+1 != ej)
// Update PHI Nodes
for (unsigned pi = 0, pe = FuncInfo->PHINodesToUpdate.size();
pi != pe; ++pi) {
MachineInstr *PHI = FuncInfo->PHINodesToUpdate[pi].first;
MachineBasicBlock *PHIBB = PHI->getParent();
assert(PHI->isPHI() &&
"This is not a machine PHI node that we are updating!");
// This is "default" BB. We have two jumps to it. From "header" BB and
// from last "case" BB.
if (PHIBB == SDB->BitTestCases[i].Default) {
// One of "cases" BB.
for (unsigned j = 0, ej = SDB->BitTestCases[i].Cases.size();
j != ej; ++j) {
MachineBasicBlock* cBB = SDB->BitTestCases[i].Cases[j].ThisBB;
if (cBB->isSuccessor(PHIBB)) {
// If the JumpTable record is filled in, then we need to emit a jump table.
// Updating the PHI nodes is tricky in this case, since we need to determine
// whether the PHI is a successor of the range check MBB or the jump table MBB
for (unsigned i = 0, e = SDB->JTCases.size(); i != e; ++i) {
// Lower header first, if it wasn't already lowered
if (!SDB->JTCases[i].first.Emitted) {
// Set the current basic block to the mbb we wish to insert the code into
FuncInfo->MBB = SDB->JTCases[i].first.HeaderBB;
FuncInfo->InsertPt = FuncInfo->MBB->end();
// Emit the code
SDB->visitJumpTableHeader(SDB->JTCases[i].second, SDB->JTCases[i].first,
// Set the current basic block to the mbb we wish to insert the code into
FuncInfo->MBB = SDB->JTCases[i].second.MBB;
FuncInfo->InsertPt = FuncInfo->MBB->end();
// Emit the code
// Update PHI Nodes
for (unsigned pi = 0, pe = FuncInfo->PHINodesToUpdate.size();
pi != pe; ++pi) {
MachineInstr *PHI = FuncInfo->PHINodesToUpdate[pi].first;
MachineBasicBlock *PHIBB = PHI->getParent();
assert(PHI->isPHI() &&
"This is not a machine PHI node that we are updating!");
// "default" BB. We can go there only from header BB.
if (PHIBB == SDB->JTCases[i].second.Default) {
// JT BB. Just iterate over successors here
if (FuncInfo->MBB->isSuccessor(PHIBB)) {
// If the switch block involved a branch to one of the actual successors, we
// need to update PHI nodes in that block.
for (unsigned i = 0, e = FuncInfo->PHINodesToUpdate.size(); i != e; ++i) {
MachineInstr *PHI = FuncInfo->PHINodesToUpdate[i].first;
assert(PHI->isPHI() &&
"This is not a machine PHI node that we are updating!");
if (FuncInfo->MBB->isSuccessor(PHI->getParent())) {
MachineOperand::CreateReg(FuncInfo->PHINodesToUpdate[i].second, false));
// If we generated any switch lowering information, build and codegen any
// additional DAGs necessary.
for (unsigned i = 0, e = SDB->SwitchCases.size(); i != e; ++i) {
// Set the current basic block to the mbb we wish to insert the code into
FuncInfo->MBB = SDB->SwitchCases[i].ThisBB;
FuncInfo->InsertPt = FuncInfo->MBB->end();
// Determine the unique successors.
SmallVector<MachineBasicBlock *, 2> Succs;
if (SDB->SwitchCases[i].TrueBB != SDB->SwitchCases[i].FalseBB)
// Emit the code. Note that this could result in FuncInfo->MBB being split.
SDB->visitSwitchCase(SDB->SwitchCases[i], FuncInfo->MBB);
// Remember the last block, now that any splitting is done, for use in
// populating PHI nodes in successors.
MachineBasicBlock *ThisBB = FuncInfo->MBB;
// Handle any PHI nodes in successors of this chunk, as if we were coming
// from the original BB before switch expansion. Note that PHI nodes can
// occur multiple times in PHINodesToUpdate. We have to be very careful to
// handle them the right number of times.
for (unsigned i = 0, e = Succs.size(); i != e; ++i) {
FuncInfo->MBB = Succs[i];
FuncInfo->InsertPt = FuncInfo->MBB->end();
// FuncInfo->MBB may have been removed from the CFG if a branch was
// constant folded.
if (ThisBB->isSuccessor(FuncInfo->MBB)) {
for (MachineBasicBlock::iterator Phi = FuncInfo->MBB->begin();
Phi != FuncInfo->MBB->end() && Phi->isPHI();
++Phi) {
// This value for this PHI node is recorded in PHINodesToUpdate.
for (unsigned pn = 0; ; ++pn) {
assert(pn != FuncInfo->PHINodesToUpdate.size() &&
"Didn't find PHI entry!");
if (FuncInfo->PHINodesToUpdate[pn].first == Phi) {
/// Create the scheduler. If a specific scheduler was specified
/// via the SchedulerRegistry, use it, otherwise select the
/// one preferred by the target.
ScheduleDAGSDNodes *SelectionDAGISel::CreateScheduler() {
RegisterScheduler::FunctionPassCtor Ctor = RegisterScheduler::getDefault();
if (!Ctor) {
Ctor = ISHeuristic;
return Ctor(this, OptLevel);
// Helper functions used by the generated instruction selector.
// Calls to these methods are generated by tblgen.
/// CheckAndMask - The isel is trying to match something like (and X, 255). If
/// the dag combiner simplified the 255, we still want to match. RHS is the
/// actual value in the DAG on the RHS of an AND, and DesiredMaskS is the value
/// specified in the .td file (e.g. 255).
bool SelectionDAGISel::CheckAndMask(SDValue LHS, ConstantSDNode *RHS,
int64_t DesiredMaskS) const {
const APInt &ActualMask = RHS->getAPIntValue();
const APInt &DesiredMask = APInt(LHS.getValueSizeInBits(), DesiredMaskS);
// If the actual mask exactly matches, success!
if (ActualMask == DesiredMask)
return true;
// If the actual AND mask is allowing unallowed bits, this doesn't match.
if (ActualMask.intersects(~DesiredMask))
return false;
// Otherwise, the DAG Combiner may have proven that the value coming in is
// either already zero or is not demanded. Check for known zero input bits.
APInt NeededMask = DesiredMask & ~ActualMask;
if (CurDAG->MaskedValueIsZero(LHS, NeededMask))
return true;
// TODO: check to see if missing bits are just not demanded.
// Otherwise, this pattern doesn't match.
return false;
/// CheckOrMask - The isel is trying to match something like (or X, 255). If
/// the dag combiner simplified the 255, we still want to match. RHS is the
/// actual value in the DAG on the RHS of an OR, and DesiredMaskS is the value
/// specified in the .td file (e.g. 255).
bool SelectionDAGISel::CheckOrMask(SDValue LHS, ConstantSDNode *RHS,
int64_t DesiredMaskS) const {
const APInt &ActualMask = RHS->getAPIntValue();
const APInt &DesiredMask = APInt(LHS.getValueSizeInBits(), DesiredMaskS);
// If the actual mask exactly matches, success!
if (ActualMask == DesiredMask)
return true;
// If the actual AND mask is allowing unallowed bits, this doesn't match.
if (ActualMask.intersects(~DesiredMask))
return false;
// Otherwise, the DAG Combiner may have proven that the value coming in is
// either already zero or is not demanded. Check for known zero input bits.
APInt NeededMask = DesiredMask & ~ActualMask;
APInt KnownZero, KnownOne;
CurDAG->ComputeMaskedBits(LHS, KnownZero, KnownOne);
// If all the missing bits in the or are already known to be set, match!
if ((NeededMask & KnownOne) == NeededMask)
return true;
// TODO: check to see if missing bits are just not demanded.
// Otherwise, this pattern doesn't match.
return false;
/// SelectInlineAsmMemoryOperands - Calls to this are automatically generated
/// by tblgen. Others should not call it.
void SelectionDAGISel::
SelectInlineAsmMemoryOperands(std::vector<SDValue> &Ops) {
std::vector<SDValue> InOps;
std::swap(InOps, Ops);
Ops.push_back(InOps[InlineAsm::Op_InputChain]); // 0
Ops.push_back(InOps[InlineAsm::Op_AsmString]); // 1
Ops.push_back(InOps[InlineAsm::Op_MDNode]); // 2, !srcloc
Ops.push_back(InOps[InlineAsm::Op_ExtraInfo]); // 3 (SideEffect, AlignStack)
unsigned i = InlineAsm::Op_FirstOperand, e = InOps.size();
if (InOps[e-1].getValueType() == MVT::Glue)
--e; // Don't process a glue operand if it is here.
while (i != e) {
unsigned Flags = cast<ConstantSDNode>(InOps[i])->getZExtValue();
if (!InlineAsm::isMemKind(Flags)) {
// Just skip over this operand, copying the operands verbatim.
Ops.insert(Ops.end(), InOps.begin()+i,
InOps.begin()+i+InlineAsm::getNumOperandRegisters(Flags) + 1);
i += InlineAsm::getNumOperandRegisters(Flags) + 1;
} else {
assert(InlineAsm::getNumOperandRegisters(Flags) == 1 &&
"Memory operand with multiple values?");
// Otherwise, this is a memory operand. Ask the target to select it.
std::vector<SDValue> SelOps;
if (SelectInlineAsmMemoryOperand(InOps[i+1], 'm', SelOps))
report_fatal_error("Could not match memory address. Inline asm"
" failure!");
// Add this to the output node.
unsigned NewFlags =
InlineAsm::getFlagWord(InlineAsm::Kind_Mem, SelOps.size());
Ops.push_back(CurDAG->getTargetConstant(NewFlags, MVT::i32));
Ops.insert(Ops.end(), SelOps.begin(), SelOps.end());
i += 2;
// Add the glue input back if present.
if (e != InOps.size())
/// findGlueUse - Return use of MVT::Glue value produced by the specified
/// SDNode.
static SDNode *findGlueUse(SDNode *N) {
unsigned FlagResNo = N->getNumValues()-1;
for (SDNode::use_iterator I = N->use_begin(), E = N->use_end(); I != E; ++I) {
SDUse &Use = I.getUse();
if (Use.getResNo() == FlagResNo)
return Use.getUser();
return NULL;
/// findNonImmUse - Return true if "Use" is a non-immediate use of "Def".
/// This function recursively traverses up the operand chain, ignoring
/// certain nodes.
static bool findNonImmUse(SDNode *Use, SDNode* Def, SDNode *ImmedUse,
SDNode *Root, SmallPtrSet<SDNode*, 16> &Visited,
bool IgnoreChains) {
// The NodeID's are given uniques ID's where a node ID is guaranteed to be
// greater than all of its (recursive) operands. If we scan to a point where
// 'use' is smaller than the node we're scanning for, then we know we will
// never find it.
// The Use may be -1 (unassigned) if it is a newly allocated node. This can
// happen because we scan down to newly selected nodes in the case of glue
// uses.
if ((Use->getNodeId() < Def->getNodeId() && Use->getNodeId() != -1))
return false;
// Don't revisit nodes if we already scanned it and didn't fail, we know we
// won't fail if we scan it again.
if (!Visited.insert(Use))
return false;
for (unsigned i = 0, e = Use->getNumOperands(); i != e; ++i) {
// Ignore chain uses, they are validated by HandleMergeInputChains.
if (Use->getOperand(i).getValueType() == MVT::Other && IgnoreChains)
SDNode *N = Use->getOperand(i).getNode();
if (N == Def) {
if (Use == ImmedUse || Use == Root)
continue; // We are not looking for immediate use.
assert(N != Root);
return true;
// Traverse up the operand chain.
if (findNonImmUse(N, Def, ImmedUse, Root, Visited, IgnoreChains))
return true;
return false;
/// IsProfitableToFold - Returns true if it's profitable to fold the specific
/// operand node N of U during instruction selection that starts at Root.
bool SelectionDAGISel::IsProfitableToFold(SDValue N, SDNode *U,
SDNode *Root) const {
if (OptLevel == CodeGenOpt::None) return false;
return N.hasOneUse();
/// IsLegalToFold - Returns true if the specific operand node N of
/// U can be folded during instruction selection that starts at Root.
bool SelectionDAGISel::IsLegalToFold(SDValue N, SDNode *U, SDNode *Root,
CodeGenOpt::Level OptLevel,
bool IgnoreChains) {
if (OptLevel == CodeGenOpt::None) return false;
// If Root use can somehow reach N through a path that that doesn't contain
// U then folding N would create a cycle. e.g. In the following
// diagram, Root can reach N through X. If N is folded into into Root, then
// X is both a predecessor and a successor of U.
// [N*] //
// ^ ^ //
// / \ //
// [U*] [X]? //
// ^ ^ //
// \ / //
// \ / //
// [Root*] //
// * indicates nodes to be folded together.
// If Root produces glue, then it gets (even more) interesting. Since it
// will be "glued" together with its glue use in the scheduler, we need to
// check if it might reach N.
// [N*] //
// ^ ^ //
// / \ //
// [U*] [X]? //
// ^ ^ //
// \ \ //
// \ | //
// [Root*] | //
// ^ | //
// f | //
// | / //
// [Y] / //
// ^ / //
// f / //
// | / //
// [GU] //
// If GU (glue use) indirectly reaches N (the load), and Root folds N
// (call it Fold), then X is a predecessor of GU and a successor of
// Fold. But since Fold and GU are glued together, this will create
// a cycle in the scheduling graph.
// If the node has glue, walk down the graph to the "lowest" node in the
// glueged set.
EVT VT = Root->getValueType(Root->getNumValues()-1);
while (VT == MVT::Glue) {
SDNode *GU = findGlueUse(Root);
if (GU == NULL)
Root = GU;
VT = Root->getValueType(Root->getNumValues()-1);
// If our query node has a glue result with a use, we've walked up it. If
// the user (which has already been selected) has a chain or indirectly uses
// the chain, our WalkChainUsers predicate will not consider it. Because of
// this, we cannot ignore chains in this predicate.
IgnoreChains = false;
SmallPtrSet<SDNode*, 16> Visited;
return !findNonImmUse(Root, N.getNode(), U, Root, Visited, IgnoreChains);
SDNode *SelectionDAGISel::Select_INLINEASM(SDNode *N) {
std::vector<SDValue> Ops(N->op_begin(), N->op_end());
std::vector<EVT> VTs;
SDValue New = CurDAG->getNode(ISD::INLINEASM, N->getDebugLoc(),
VTs, &Ops[0], Ops.size());
return New.getNode();
SDNode *SelectionDAGISel::Select_UNDEF(SDNode *N) {
return CurDAG->SelectNodeTo(N, TargetOpcode::IMPLICIT_DEF,N->getValueType(0));
/// GetVBR - decode a vbr encoding whose top bit is set.
GetVBR(uint64_t Val, const unsigned char *MatcherTable, unsigned &Idx) {
assert(Val >= 128 && "Not a VBR");
Val &= 127; // Remove first vbr bit.
unsigned Shift = 7;
uint64_t NextBits;
do {
NextBits = MatcherTable[Idx++];
Val |= (NextBits&127) << Shift;
Shift += 7;
} while (NextBits & 128);
return Val;
/// UpdateChainsAndGlue - When a match is complete, this method updates uses of
/// interior glue and chain results to use the new glue and chain results.
void SelectionDAGISel::
UpdateChainsAndGlue(SDNode *NodeToMatch, SDValue InputChain,
const SmallVectorImpl<SDNode*> &ChainNodesMatched,
SDValue InputGlue,
const SmallVectorImpl<SDNode*> &GlueResultNodesMatched,
bool isMorphNodeTo) {
SmallVector<SDNode*, 4> NowDeadNodes;
ISelUpdater ISU(ISelPosition);
// Now that all the normal results are replaced, we replace the chain and
// glue results if present.
if (!ChainNodesMatched.empty()) {
assert(InputChain.getNode() != 0 &&
"Matched input chains but didn't produce a chain");
// Loop over all of the nodes we matched that produced a chain result.
// Replace all the chain results with the final chain we ended up with.
for (unsigned i = 0, e = ChainNodesMatched.size(); i != e; ++i) {
SDNode *ChainNode = ChainNodesMatched[i];
// If this node was already deleted, don't look at it.
if (ChainNode->getOpcode() == ISD::DELETED_NODE)
// Don't replace the results of the root node if we're doing a
// MorphNodeTo.
if (ChainNode == NodeToMatch && isMorphNodeTo)
SDValue ChainVal = SDValue(ChainNode, ChainNode->getNumValues()-1);
if (ChainVal.getValueType() == MVT::Glue)
ChainVal = ChainVal.getValue(ChainVal->getNumValues()-2);
assert(ChainVal.getValueType() == MVT::Other && "Not a chain?");
CurDAG->ReplaceAllUsesOfValueWith(ChainVal, InputChain, &ISU);
// If the node became dead and we haven't already seen it, delete it.
if (ChainNode->use_empty() &&
!std::count(NowDeadNodes.begin(), NowDeadNodes.end(), ChainNode))
// If the result produces glue, update any glue results in the matched
// pattern with the glue result.
if (InputGlue.getNode() != 0) {
// Handle any interior nodes explicitly marked.
for (unsigned i = 0, e = GlueResultNodesMatched.size(); i != e; ++i) {
SDNode *FRN = GlueResultNodesMatched[i];
// If this node was already deleted, don't look at it.
if (FRN->getOpcode() == ISD::DELETED_NODE)
assert(FRN->getValueType(FRN->getNumValues()-1) == MVT::Glue &&
"Doesn't have a glue result");
CurDAG->ReplaceAllUsesOfValueWith(SDValue(FRN, FRN->getNumValues()-1),
InputGlue, &ISU);
// If the node became dead and we haven't already seen it, delete it.
if (FRN->use_empty() &&
!std::count(NowDeadNodes.begin(), NowDeadNodes.end(), FRN))
if (!NowDeadNodes.empty())
CurDAG->RemoveDeadNodes(NowDeadNodes, &ISU);
DEBUG(errs() << "ISEL: Match complete!\n");
enum ChainResult {
/// WalkChainUsers - Walk down the users of the specified chained node that is
/// part of the pattern we're matching, looking at all of the users we find.
/// This determines whether something is an interior node, whether we have a
/// non-pattern node in between two pattern nodes (which prevent folding because
/// it would induce a cycle) and whether we have a TokenFactor node sandwiched
/// between pattern nodes (in which case the TF becomes part of the pattern).
/// The walk we do here is guaranteed to be small because we quickly get down to
/// already selected nodes "below" us.
static ChainResult
WalkChainUsers(SDNode *ChainedNode,
SmallVectorImpl<SDNode*> &ChainedNodesInPattern,
SmallVectorImpl<SDNode*> &InteriorChainedNodes) {
ChainResult Result = CR_Simple;
for (SDNode::use_iterator UI = ChainedNode->use_begin(),
E = ChainedNode->use_end(); UI != E; ++UI) {
// Make sure the use is of the chain, not some other value we produce.
if (UI.getUse().getValueType() != MVT::Other) continue;
SDNode *User = *UI;
// If we see an already-selected machine node, then we've gone beyond the
// pattern that we're selecting down into the already selected chunk of the
// DAG.
if (User->isMachineOpcode() ||
User->getOpcode() == ISD::HANDLENODE) // Root of the graph.
if (User->getOpcode() == ISD::CopyToReg ||
User->getOpcode() == ISD::CopyFromReg ||
User->getOpcode() == ISD::INLINEASM ||
User->getOpcode() == ISD::EH_LABEL) {
// If their node ID got reset to -1 then they've already been selected.
// Treat them like a MachineOpcode.
if (User->getNodeId() == -1)
// If we have a TokenFactor, we handle it specially.
if (User->getOpcode() != ISD::TokenFactor) {
// If the node isn't a token factor and isn't part of our pattern, then it
// must be a random chained node in between two nodes we're selecting.
// This happens when we have something like:
// x = load ptr
// call
// y = x+4
// store y -> ptr
// Because we structurally match the load/store as a read/modify/write,
// but the call is chained between them. We cannot fold in this case
// because it would induce a cycle in the graph.
if (!std::count(ChainedNodesInPattern.begin(),
ChainedNodesInPattern.end(), User))
return CR_InducesCycle;
// Otherwise we found a node that is part of our pattern. For example in:
// x = load ptr
// y = x+4
// store y -> ptr
// This would happen when we're scanning down from the load and see the
// store as a user. Record that there is a use of ChainedNode that is
// part of the pattern and keep scanning uses.
Result = CR_LeadsToInteriorNode;
// If we found a TokenFactor, there are two cases to consider: first if the
// TokenFactor is just hanging "below" the pattern we're matching (i.e. no
// uses of the TF are in our pattern) we just want to ignore it. Second,
// the TokenFactor can be sandwiched in between two chained nodes, like so:
// [Load chain]
// ^
// |
// [Load]
// ^ ^
// | \ DAG's like cheese
// / \ do you?
// / |
// [TokenFactor] [Op]
// ^ ^
// | |
// \ /
// \ /
// [Store]
// In this case, the TokenFactor becomes part of our match and we rewrite it
// as a new TokenFactor.
// To distinguish these two cases, do a recursive walk down the uses.
switch (WalkChainUsers(User, ChainedNodesInPattern, InteriorChainedNodes)) {
case CR_Simple:
// If the uses of the TokenFactor are just already-selected nodes, ignore
// it, it is "below" our pattern.
case CR_InducesCycle:
// If the uses of the TokenFactor lead to nodes that are not part of our
// pattern that are not selected, folding would turn this into a cycle,
// bail out now.
return CR_InducesCycle;
case CR_LeadsToInteriorNode:
break; // Otherwise, keep processing.
// Okay, we know we're in the interesting interior case. The TokenFactor
// is now going to be considered part of the pattern so that we rewrite its
// uses (it may have uses that are not part of the pattern) with the
// ultimate chain result of the generated code. We will also add its chain
// inputs as inputs to the ultimate TokenFactor we create.
Result = CR_LeadsToInteriorNode;
return Result;
/// HandleMergeInputChains - This implements the OPC_EmitMergeInputChains
/// operation for when the pattern matched at least one node with a chains. The
/// input vector contains a list of all of the chained nodes that we match. We
/// must determine if this is a valid thing to cover (i.e. matching it won't
/// induce cycles in the DAG) and if so, creating a TokenFactor node. that will
/// be used as the input node chain for the generated nodes.
static SDValue
HandleMergeInputChains(SmallVectorImpl<SDNode*> &ChainNodesMatched,
SelectionDAG *CurDAG) {
// Walk all of the chained nodes we've matched, recursively scanning down the
// users of the chain result. This adds any TokenFactor nodes that are caught
// in between chained nodes to the chained and interior nodes list.
SmallVector<SDNode*, 3> InteriorChainedNodes;
for (unsigned i = 0, e = ChainNodesMatched.size(); i != e; ++i) {
if (WalkChainUsers(ChainNodesMatched[i], ChainNodesMatched,
InteriorChainedNodes) == CR_InducesCycle)
return SDValue(); // Would induce a cycle.
// Okay, we have walked all the matched nodes and collected TokenFactor nodes
// that we are interested in. Form our input TokenFactor node.
SmallVector<SDValue, 3> InputChains;
for (unsigned i = 0, e = ChainNodesMatched.size(); i != e; ++i) {
// Add the input chain of this node to the InputChains list (which will be
// the operands of the generated TokenFactor) if it's not an interior node.
SDNode *N = ChainNodesMatched[i];
if (N->getOpcode() != ISD::TokenFactor) {
if (std::count(InteriorChainedNodes.begin(),InteriorChainedNodes.end(),N))
// Otherwise, add the input chain.
SDValue InChain = ChainNodesMatched[i]->getOperand(0);
assert(InChain.getValueType() == MVT::Other && "Not a chain");
// If we have a token factor, we want to add all inputs of the token factor
// that are not part of the pattern we're matching.
for (unsigned op = 0, e = N->getNumOperands(); op != e; ++op) {
if (!std::count(ChainNodesMatched.begin(), ChainNodesMatched.end(),
SDValue Res;
if (InputChains.size() == 1)
return InputChains[0];
return CurDAG->getNode(ISD::TokenFactor, ChainNodesMatched[0]->getDebugLoc(),
MVT::Other, &InputChains[0], InputChains.size());
/// MorphNode - Handle morphing a node in place for the selector.
SDNode *SelectionDAGISel::
MorphNode(SDNode *Node, unsigned TargetOpc, SDVTList VTList,
const SDValue *Ops, unsigned NumOps, unsigned EmitNodeInfo) {
// It is possible we're using MorphNodeTo to replace a node with no
// normal results with one that has a normal result (or we could be
// adding a chain) and the input could have glue and chains as well.
// In this case we need to shift the operands down.
// FIXME: This is a horrible hack and broken in obscure cases, no worse
// than the old isel though.
int OldGlueResultNo = -1, OldChainResultNo = -1;
unsigned NTMNumResults = Node->getNumValues();
if (Node->getValueType(NTMNumResults-1) == MVT::Glue) {
OldGlueResultNo = NTMNumResults-1;
if (NTMNumResults != 1 &&
Node->getValueType(NTMNumResults-2) == MVT::Other)
OldChainResultNo = NTMNumResults-2;
} else if (Node->getValueType(NTMNumResults-1) == MVT::Other)
OldChainResultNo = NTMNumResults-1;
// Call the underlying SelectionDAG routine to do the transmogrification. Note
// that this deletes operands of the old node that become dead.
SDNode *Res = CurDAG->MorphNodeTo(Node, ~TargetOpc, VTList, Ops, NumOps);
// MorphNodeTo can operate in two ways: if an existing node with the
// specified operands exists, it can just return it. Otherwise, it
// updates the node in place to have the requested operands.
if (Res == Node) {
// If we updated the node in place, reset the node ID. To the isel,
// this should be just like a newly allocated machine node.
unsigned ResNumResults = Res->getNumValues();
// Move the glue if needed.
if ((EmitNodeInfo & OPFL_GlueOutput) && OldGlueResultNo != -1 &&
(unsigned)OldGlueResultNo != ResNumResults-1)
CurDAG->ReplaceAllUsesOfValueWith(SDValue(Node, OldGlueResultNo),
SDValue(Res, ResNumResults-1));
if ((EmitNodeInfo & OPFL_GlueOutput) != 0)
// Move the chain reference if needed.
if ((EmitNodeInfo & OPFL_Chain) && OldChainResultNo != -1 &&
(unsigned)OldChainResultNo != ResNumResults-1)
CurDAG->ReplaceAllUsesOfValueWith(SDValue(Node, OldChainResultNo),
SDValue(Res, ResNumResults-1));
// Otherwise, no replacement happened because the node already exists. Replace
// Uses of the old node with the new one.
if (Res != Node)
CurDAG->ReplaceAllUsesWith(Node, Res);
return Res;
/// CheckPatternPredicate - Implements OP_CheckPatternPredicate.
CheckSame(const unsigned char *MatcherTable, unsigned &MatcherIndex,
SDValue N,
const SmallVectorImpl<std::pair<SDValue, SDNode*> > &RecordedNodes) {
// Accept if it is exactly the same as a previously recorded node.
unsigned RecNo = MatcherTable[MatcherIndex++];
assert(RecNo < RecordedNodes.size() && "Invalid CheckSame");
return N == RecordedNodes[RecNo].first;
/// CheckPatternPredicate - Implements OP_CheckPatternPredicate.
CheckPatternPredicate(const unsigned char *MatcherTable, unsigned &MatcherIndex,
SelectionDAGISel &SDISel) {
return SDISel.CheckPatternPredicate(MatcherTable[MatcherIndex++]);
/// CheckNodePredicate - Implements OP_CheckNodePredicate.
CheckNodePredicate(const unsigned char *MatcherTable, unsigned &MatcherIndex,
SelectionDAGISel &SDISel, SDNode *N) {
return SDISel.CheckNodePredicate(N, MatcherTable[MatcherIndex++]);
CheckOpcode(const unsigned char *MatcherTable, unsigned &MatcherIndex,
SDNode *N) {
uint16_t Opc = MatcherTable[MatcherIndex++];
Opc |= (unsigned short)MatcherTable[MatcherIndex++] << 8;
return N->getOpcode() == Opc;
CheckType(const unsigned char *MatcherTable, unsigned &MatcherIndex,
SDValue N, const TargetLowering &TLI) {
MVT::SimpleValueType VT = (MVT::SimpleValueType)MatcherTable[MatcherIndex++];
if (N.getValueType() == VT) return true;
// Handle the case when VT is iPTR.
return VT == MVT::iPTR && N.getValueType() == TLI.getPointerTy();
CheckChildType(const unsigned char *MatcherTable, unsigned &MatcherIndex,
SDValue N, const TargetLowering &TLI,
unsigned ChildNo) {
if (ChildNo >= N.getNumOperands())
return false; // Match fails if out of range child #.
return ::CheckType(MatcherTable, MatcherIndex, N.getOperand(ChildNo), TLI);
CheckCondCode(const unsigned char *MatcherTable, unsigned &MatcherIndex,
SDValue N) {
return cast<CondCodeSDNode>(N)->get() ==
CheckValueType(const unsigned char *MatcherTable, unsigned &MatcherIndex,
SDValue N, const TargetLowering &TLI) {
MVT::SimpleValueType VT = (MVT::SimpleValueType)MatcherTable[MatcherIndex++];
if (cast<VTSDNode>(N)->getVT() == VT)
return true;
// Handle the case when VT is iPTR.
return VT == MVT::iPTR && cast<VTSDNode>(N)->getVT() == TLI.getPointerTy();
CheckInteger(const unsigned char *MatcherTable, unsigned &MatcherIndex,
SDValue N) {
int64_t Val = MatcherTable[MatcherIndex++];
if (Val & 128)
Val = GetVBR(Val, MatcherTable, MatcherIndex);
ConstantSDNode *C = dyn_cast<ConstantSDNode>(N);
return C != 0 && C->getSExtValue() == Val;
CheckAndImm(const unsigned char *MatcherTable, unsigned &MatcherIndex,
SDValue N, SelectionDAGISel &SDISel) {
int64_t Val = MatcherTable[MatcherIndex++];
if (Val & 128)
Val = GetVBR(Val, MatcherTable, MatcherIndex);
if (N->getOpcode() != ISD::AND) return false;
ConstantSDNode *C = dyn_cast<ConstantSDNode>(N->getOperand(1));
return C != 0 && SDISel.CheckAndMask(N.getOperand(0), C, Val);
CheckOrImm(const unsigned char *MatcherTable, unsigned &MatcherIndex,
SDValue N, SelectionDAGISel &SDISel) {
int64_t Val = MatcherTable[MatcherIndex++];
if (Val & 128)
Val = GetVBR(Val, MatcherTable, MatcherIndex);
if (N->getOpcode() != ISD::OR) return false;
ConstantSDNode *C = dyn_cast<ConstantSDNode>(N->getOperand(1));
return C != 0 && SDISel.CheckOrMask(N.getOperand(0), C, Val);
/// IsPredicateKnownToFail - If we know how and can do so without pushing a
/// scope, evaluate the current node. If the current predicate is known to
/// fail, set Result=true and return anything. If the current predicate is
/// known to pass, set Result=false and return the MatcherIndex to continue
/// with. If the current predicate is unknown, set Result=false and return the
/// MatcherIndex to continue with.
static unsigned IsPredicateKnownToFail(const unsigned char *Table,
unsigned Index, SDValue N,
bool &Result, SelectionDAGISel &SDISel,
SmallVectorImpl<std::pair<SDValue, SDNode*> > &RecordedNodes) {
switch (Table[Index++]) {
Result = false;
return Index-1; // Could not evaluate this predicate.
case SelectionDAGISel::OPC_CheckSame:
Result = !::CheckSame(Table, Index, N, RecordedNodes);
return Index;
case SelectionDAGISel::OPC_CheckPatternPredicate:
Result = !::CheckPatternPredicate(Table, Index, SDISel);
return Index;
case SelectionDAGISel::OPC_CheckPredicate:
Result = !::CheckNodePredicate(Table, Index, SDISel, N.getNode());
return Index;
case SelectionDAGISel::OPC_CheckOpcode:
Result = !::CheckOpcode(Table, Index, N.getNode());
return Index;
case SelectionDAGISel::OPC_CheckType:
Result = !::CheckType(Table, Index, N, SDISel.TLI);
return Index;
case SelectionDAGISel::OPC_CheckChild0Type:
case SelectionDAGISel::OPC_CheckChild1Type:
case SelectionDAGISel::OPC_CheckChild2Type:
case SelectionDAGISel::OPC_CheckChild3Type:
case SelectionDAGISel::OPC_CheckChild4Type:
case SelectionDAGISel::OPC_CheckChild5Type:
case SelectionDAGISel::OPC_CheckChild6Type:
case SelectionDAGISel::OPC_CheckChild7Type:
Result = !::CheckChildType(Table, Index, N, SDISel.TLI,
Table[Index-1] - SelectionDAGISel::OPC_CheckChild0Type);
return Index;
case SelectionDAGISel::OPC_CheckCondCode:
Result = !::CheckCondCode(Table, Index, N);
return Index;
case SelectionDAGISel::OPC_CheckValueType:
Result = !::CheckValueType(Table, Index, N, SDISel.TLI);
return Index;
case SelectionDAGISel::OPC_CheckInteger:
Result = !::CheckInteger(Table, Index, N);
return Index;
case SelectionDAGISel::OPC_CheckAndImm:
Result = !::CheckAndImm(Table, Index, N, SDISel);
return Index;
case SelectionDAGISel::OPC_CheckOrImm:
Result = !::CheckOrImm(Table, Index, N, SDISel);
return Index;
namespace {
struct MatchScope {
/// FailIndex - If this match fails, this is the index to continue with.
unsigned FailIndex;
/// NodeStack - The node stack when the scope was formed.
SmallVector<SDValue, 4> NodeStack;
/// NumRecordedNodes - The number of recorded nodes when the scope was formed.
unsigned NumRecordedNodes;
/// NumMatchedMemRefs - The number of matched memref entries.
unsigned NumMatchedMemRefs;
/// InputChain/InputGlue - The current chain/glue
SDValue InputChain, InputGlue;
/// HasChainNodesMatched - True if the ChainNodesMatched list is non-empty.
bool HasChainNodesMatched, HasGlueResultNodesMatched;
SDNode *SelectionDAGISel::
SelectCodeCommon(SDNode *NodeToMatch, const unsigned char *MatcherTable,
unsigned TableSize) {
// FIXME: Should these even be selected? Handle these cases in the caller?
switch (NodeToMatch->getOpcode()) {
case ISD::EntryToken: // These nodes remain the same.
case ISD::BasicBlock:
case ISD::Register:
case ISD::RegisterMask:
case ISD::TargetConstant:
case ISD::TargetConstantFP:
case ISD::TargetConstantPool:
case ISD::TargetFrameIndex:
case ISD::TargetExternalSymbol:
case ISD::TargetBlockAddress:
case ISD::TargetJumpTable:
case ISD::TargetGlobalTLSAddress:
case ISD::TargetGlobalAddress:
case ISD::TokenFactor:
case ISD::CopyFromReg:
case ISD::CopyToReg:
NodeToMatch->setNodeId(-1); // Mark selected.
return 0;
case ISD::AssertSext:
case ISD::AssertZext:
CurDAG->ReplaceAllUsesOfValueWith(SDValue(NodeToMatch, 0),
return 0;
case ISD::INLINEASM: return Select_INLINEASM(NodeToMatch);
case ISD::UNDEF: return Select_UNDEF(NodeToMatch);
assert(!NodeToMatch->isMachineOpcode() && "Node already selected!");
// Set up the node stack with NodeToMatch as the only node on the stack.
SmallVector<SDValue, 8> NodeStack;
SDValue N = SDValue(NodeToMatch, 0);
// MatchScopes - Scopes used when matching, if a match failure happens, this
// indicates where to continue checking.
SmallVector<MatchScope, 8> MatchScopes;
// RecordedNodes - This is the set of nodes that have been recorded by the
// state machine. The second value is the parent of the node, or null if the
// root is recorded.
SmallVector<std::pair<SDValue, SDNode*>, 8> RecordedNodes;
// MatchedMemRefs - This is the set of MemRef's we've seen in the input
// pattern.
SmallVector<MachineMemOperand*, 2> MatchedMemRefs;
// These are the current input chain and glue for use when generating nodes.
// Various Emit operations change these. For example, emitting a copytoreg
// uses and updates these.
SDValue InputChain, InputGlue;
// ChainNodesMatched - If a pattern matches nodes that have input/output
// chains, the OPC_EmitMergeInputChains operation is emitted which indicates
// which ones they are. The result is captured into this list so that we can
// update the chain results when the pattern is complete.
SmallVector<SDNode*, 3> ChainNodesMatched;
SmallVector<SDNode*, 3> GlueResultNodesMatched;
DEBUG(errs() << "ISEL: Starting pattern match on root node: ";
errs() << '\n');
// Determine where to start the interpreter. Normally we start at opcode #0,
// but if the state machine starts with an OPC_SwitchOpcode, then we
// accelerate the first lookup (which is guaranteed to be hot) with the
// OpcodeOffset table.
unsigned MatcherIndex = 0;
if (!OpcodeOffset.empty()) {
// Already computed the OpcodeOffset table, just index into it.
if (N.getOpcode() < OpcodeOffset.size())
MatcherIndex = OpcodeOffset[N.getOpcode()];
DEBUG(errs() << " Initial Opcode index to " << MatcherIndex << "\n");
} else if (MatcherTable[0] == OPC_SwitchOpcode) {
// Otherwise, the table isn't computed, but the state machine does start
// with an OPC_SwitchOpcode instruction. Populate the table now, since this
// is the first time we're selecting an instruction.
unsigned Idx = 1;
while (1) {
// Get the size of this case.
unsigned CaseSize = MatcherTable[Idx++];
if (CaseSize & 128)
CaseSize = GetVBR(CaseSize, MatcherTable, Idx);
if (CaseSize == 0) break;
// Get the opcode, add the index to the table.
uint16_t Opc = MatcherTable[Idx++];
Opc |= (unsigned short)MatcherTable[Idx++] << 8;
if (Opc >= OpcodeOffset.size())
OpcodeOffset[Opc] = Idx;
Idx += CaseSize;
// Okay, do the lookup for the first opcode.
if (N.getOpcode() < OpcodeOffset.size())
MatcherIndex = OpcodeOffset[N.getOpcode()];
while (1) {
assert(MatcherIndex < TableSize && "Invalid index");
#ifndef NDEBUG
unsigned CurrentOpcodeIndex = MatcherIndex;
BuiltinOpcodes Opcode = (BuiltinOpcodes)MatcherTable[MatcherIndex++];
switch (Opcode) {
case OPC_Scope: {
// Okay, the semantics of this operation are that we should push a scope
// then evaluate the first child. However, pushing a scope only to have
// the first check fail (which then pops it) is inefficient. If we can
// determine immediately that the first check (or first several) will
// immediately fail, don't even bother pushing a scope for them.
unsigned FailIndex;
while (1) {
unsigned NumToSkip = MatcherTable[MatcherIndex++];
if (NumToSkip & 128)
NumToSkip = GetVBR(NumToSkip, MatcherTable, MatcherIndex);
// Found the end of the scope with no match.
if (NumToSkip == 0) {
FailIndex = 0;
FailIndex = MatcherIndex+NumToSkip;
unsigned MatcherIndexOfPredicate = MatcherIndex;
(void)MatcherIndexOfPredicate; // silence warning.
// If we can't evaluate this predicate without pushing a scope (e.g. if
// it is a 'MoveParent') or if the predicate succeeds on this node, we
// push the scope and evaluate the full predicate chain.
bool Result;
MatcherIndex = IsPredicateKnownToFail(MatcherTable, MatcherIndex, N,
Result, *this, RecordedNodes);
if (!Result)
DEBUG(errs() << " Skipped scope entry (due to false predicate) at "
<< "index " << MatcherIndexOfPredicate
<< ", continuing at " << FailIndex << "\n");
// Otherwise, we know that this case of the Scope is guaranteed to fail,
// move to the next case.
MatcherIndex = FailIndex;
// If the whole scope failed to match, bail.
if (FailIndex == 0) break;
// Push a MatchScope which indicates where to go if the first child fails
// to match.
MatchScope NewEntry;
NewEntry.FailIndex = FailIndex;
NewEntry.NodeStack.append(NodeStack.begin(), NodeStack.end());
NewEntry.NumRecordedNodes = RecordedNodes.size();
NewEntry.NumMatchedMemRefs = MatchedMemRefs.size();
NewEntry.InputChain = InputChain;
NewEntry.InputGlue = InputGlue;
NewEntry.HasChainNodesMatched = !ChainNodesMatched.empty();
NewEntry.HasGlueResultNodesMatched = !GlueResultNodesMatched.empty();
case OPC_RecordNode: {
// Remember this node, it may end up being an operand in the pattern.
SDNode *Parent = 0;
if (NodeStack.size() > 1)
Parent = NodeStack[NodeStack.size()-2].getNode();
RecordedNodes.push_back(std::make_pair(N, Parent));
case OPC_RecordChild0: case OPC_RecordChild1:
case OPC_RecordChild2: case OPC_RecordChild3:
case OPC_RecordChild4: case OPC_RecordChild5:
case OPC_RecordChild6: case OPC_RecordChild7: {
unsigned ChildNo = Opcode-OPC_RecordChild0;
if (ChildNo >= N.getNumOperands())
break; // Match fails if out of range child #.
case OPC_RecordMemRef:
case OPC_CaptureGlueInput:
// If the current node has an input glue, capture it in InputGlue.
if (N->getNumOperands() != 0 &&
N->getOperand(N->getNumOperands()-1).getValueType() == MVT::Glue)
InputGlue = N->getOperand(N->getNumOperands()-1);
case OPC_MoveChild: {
unsigned ChildNo = MatcherTable[MatcherIndex++];
if (ChildNo >= N.getNumOperands())
break; // Match fails if out of range child #.
N = N.getOperand(ChildNo);
case OPC_MoveParent:
// Pop the current node off the NodeStack.
assert(!NodeStack.empty() && "Node stack imbalance!");
N = NodeStack.back();
case OPC_CheckSame:
if (!::CheckSame(MatcherTable, MatcherIndex, N, RecordedNodes)) break;
case OPC_CheckPatternPredicate:
if (!::CheckPatternPredicate(MatcherTable, MatcherIndex, *this)) break;
case OPC_CheckPredicate:
if (!::CheckNodePredicate(MatcherTable, MatcherIndex, *this,
case OPC_CheckComplexPat: {
unsigned CPNum = MatcherTable[MatcherIndex++];
unsigned RecNo = MatcherTable[MatcherIndex++];
assert(RecNo < RecordedNodes.size() && "Invalid CheckComplexPat");
if (!CheckComplexPattern(NodeToMatch, RecordedNodes[RecNo].second,
RecordedNodes[RecNo].first, CPNum,
case OPC_CheckOpcode:
if (!::CheckOpcode(MatcherTable, MatcherIndex, N.getNode())) break;
case OPC_CheckType:
if (!::CheckType(MatcherTable, MatcherIndex, N, TLI)) break;
case OPC_SwitchOpcode: {
unsigned CurNodeOpcode = N.getOpcode();
unsigned SwitchStart = MatcherIndex-1; (void)SwitchStart;
unsigned CaseSize;
while (1) {
// Get the size of this case.
CaseSize = MatcherTable[MatcherIndex++];
if (CaseSize & 128)
CaseSize = GetVBR(CaseSize, MatcherTable, MatcherIndex);
if (CaseSize == 0) break;
uint16_t Opc = MatcherTable[MatcherIndex++];
Opc |= (unsigned short)MatcherTable[MatcherIndex++] << 8;
// If the opcode matches, then we will execute this case.
if (CurNodeOpcode == Opc)
// Otherwise, skip over this case.
MatcherIndex += CaseSize;
// If no cases matched, bail out.
if (CaseSize == 0) break;
// Otherwise, execute the case we found.
DEBUG(errs() << " OpcodeSwitch from " << SwitchStart
<< " to " << MatcherIndex << "\n");
case OPC_SwitchType: {
MVT CurNodeVT = N.getValueType().getSimpleVT();
unsigned SwitchStart = MatcherIndex-1; (void)SwitchStart;
unsigned CaseSize;
while (1) {
// Get the size of this case.
CaseSize = MatcherTable[MatcherIndex++];
if (CaseSize & 128)
CaseSize = GetVBR(CaseSize, MatcherTable, MatcherIndex);
if (CaseSize == 0) break;
MVT CaseVT = (MVT::SimpleValueType)MatcherTable[MatcherIndex++];
if (CaseVT == MVT::iPTR)
CaseVT = TLI.getPointerTy();
// If the VT matches, then we will execute this case.
if (CurNodeVT == CaseVT)
// Otherwise, skip over this case.
MatcherIndex += CaseSize;