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llvm-6502/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
Dan Gohman 3df24e667f Create HandlePHINodesInSuccessorBlocksFast, a version of 
HandlePHINodesInSuccessorBlocks that works FastISel-style. This
allows PHI nodes to be updated correctly while using FastISel.

This also involves some code reorganization; ValueMap and
MBBMap are now members of the FastISel class, so they needn't
be passed around explicitly anymore. Also, SelectInstructions
is changed to SelectInstruction, and only does one instruction
at a time.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@55746 91177308-0d34-0410-b5e6-96231b3b80d8
2008-09-03 23:12:08 +00:00

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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 "llvm/CodeGen/SelectionDAGISel.h"
#include "SelectionDAGBuild.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Constants.h"
#include "llvm/CallingConv.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
#include "llvm/GlobalVariable.h"
#include "llvm/InlineAsm.h"
#include "llvm/Instructions.h"
#include "llvm/Intrinsics.h"
#include "llvm/IntrinsicInst.h"
#include "llvm/ParameterAttributes.h"
#include "llvm/CodeGen/FastISel.h"
#include "llvm/CodeGen/GCStrategy.h"
#include "llvm/CodeGen/GCMetadata.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineJumpTableInfo.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/ScheduleDAG.h"
#include "llvm/CodeGen/SchedulerRegistry.h"
#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetFrameInfo.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/Timer.h"
#include <algorithm>
using namespace llvm;
static cl::opt<bool>
EnableValueProp("enable-value-prop", cl::Hidden);
static cl::opt<bool>
EnableLegalizeTypes("enable-legalize-types", cl::Hidden);
static cl::opt<bool>
EnableFastISel("fast-isel", cl::Hidden,
cl::desc("Enable the experimental \"fast\" instruction selector"));
static cl::opt<bool>
DisableFastISelAbort("fast-isel-no-abort", cl::Hidden,
cl::desc("Use the SelectionDAGISel when \"fast\" instruction "
"selection fails"));
#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>
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"));
#else
static const bool ViewDAGCombine1 = false,
ViewLegalizeTypesDAGs = false, ViewLegalizeDAGs = false,
ViewDAGCombine2 = false,
ViewISelDAGs = false, ViewSchedDAGs = false,
ViewSUnitDAGs = false;
#endif
//===---------------------------------------------------------------------===//
///
/// 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> >
ISHeuristic("pre-RA-sched",
cl::init(&createDefaultScheduler),
cl::desc("Instruction schedulers available (before register"
" allocation):"));
static RegisterScheduler
defaultListDAGScheduler("default", " Best scheduler for the target",
createDefaultScheduler);
namespace llvm {
//===--------------------------------------------------------------------===//
/// createDefaultScheduler - This creates an instruction scheduler appropriate
/// for the target.
ScheduleDAG* createDefaultScheduler(SelectionDAGISel *IS,
SelectionDAG *DAG,
MachineBasicBlock *BB,
bool Fast) {
TargetLowering &TLI = IS->getTargetLowering();
if (TLI.getSchedulingPreference() == TargetLowering::SchedulingForLatency) {
return createTDListDAGScheduler(IS, DAG, BB, Fast);
} else {
assert(TLI.getSchedulingPreference() ==
TargetLowering::SchedulingForRegPressure && "Unknown sched type!");
return createBURRListDAGScheduler(IS, DAG, BB, Fast);
}
}
}
// EmitInstrWithCustomInserter - This method should be implemented by targets
// that mark instructions with the 'usesCustomDAGSchedInserter' 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 the scheduler passes ownership of it to this method.
MachineBasicBlock *TargetLowering::EmitInstrWithCustomInserter(MachineInstr *MI,
MachineBasicBlock *MBB) {
cerr << "If a target marks an instruction with "
<< "'usesCustomDAGSchedInserter', it must implement "
<< "TargetLowering::EmitInstrWithCustomInserter!\n";
abort();
return 0;
}
//===----------------------------------------------------------------------===//
// SelectionDAGISel code
//===----------------------------------------------------------------------===//
SelectionDAGISel::SelectionDAGISel(TargetLowering &tli, bool fast) :
FunctionPass((intptr_t)&ID), TLI(tli),
FuncInfo(new FunctionLoweringInfo(TLI)),
CurDAG(new SelectionDAG(TLI, *FuncInfo)),
SDL(new SelectionDAGLowering(*CurDAG, TLI, *FuncInfo)),
GFI(),
Fast(fast),
DAGSize(0)
{}
SelectionDAGISel::~SelectionDAGISel() {
delete SDL;
delete CurDAG;
delete FuncInfo;
}
unsigned SelectionDAGISel::MakeReg(MVT VT) {
return RegInfo->createVirtualRegister(TLI.getRegClassFor(VT));
}
void SelectionDAGISel::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<AliasAnalysis>();
AU.addRequired<GCModuleInfo>();
AU.setPreservesAll();
}
bool SelectionDAGISel::runOnFunction(Function &Fn) {
// Get alias analysis for load/store combining.
AA = &getAnalysis<AliasAnalysis>();
MachineFunction &MF = MachineFunction::construct(&Fn, TLI.getTargetMachine());
if (MF.getFunction()->hasGC())
GFI = &getAnalysis<GCModuleInfo>().getFunctionInfo(*MF.getFunction());
else
GFI = 0;
RegInfo = &MF.getRegInfo();
DOUT << "\n\n\n=== " << Fn.getName() << "\n";
FuncInfo->set(Fn, MF, EnableFastISel);
CurDAG->init(MF, getAnalysisToUpdate<MachineModuleInfo>());
SDL->init(GFI, *AA);
for (Function::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I)
if (InvokeInst *Invoke = dyn_cast<InvokeInst>(I->getTerminator()))
// Mark landing pad.
FuncInfo->MBBMap[Invoke->getSuccessor(1)]->setIsLandingPad();
SelectAllBasicBlocks(Fn, MF);
// Add function live-ins to entry block live-in set.
BasicBlock *EntryBB = &Fn.getEntryBlock();
BB = FuncInfo->MBBMap[EntryBB];
if (!RegInfo->livein_empty())
for (MachineRegisterInfo::livein_iterator I = RegInfo->livein_begin(),
E = RegInfo->livein_end(); I != E; ++I)
BB->addLiveIn(I->first);
#ifndef NDEBUG
assert(FuncInfo->CatchInfoFound.size() == FuncInfo->CatchInfoLost.size() &&
"Not all catch info was assigned to a landing pad!");
#endif
FuncInfo->clear();
return true;
}
static void copyCatchInfo(BasicBlock *SrcBB, BasicBlock *DestBB,
MachineModuleInfo *MMI, FunctionLoweringInfo &FLI) {
for (BasicBlock::iterator I = SrcBB->begin(), E = --SrcBB->end(); I != E; ++I)
if (EHSelectorInst *EHSel = dyn_cast<EHSelectorInst>(I)) {
// Apply the catch info to DestBB.
AddCatchInfo(*EHSel, MMI, FLI.MBBMap[DestBB]);
#ifndef NDEBUG
if (!FLI.MBBMap[SrcBB]->isLandingPad())
FLI.CatchInfoFound.insert(EHSel);
#endif
}
}
/// IsFixedFrameObjectWithPosOffset - Check if object is a fixed frame object and
/// whether object offset >= 0.
static bool
IsFixedFrameObjectWithPosOffset(MachineFrameInfo * MFI, SDValue Op) {
if (!isa<FrameIndexSDNode>(Op)) return false;
FrameIndexSDNode * FrameIdxNode = dyn_cast<FrameIndexSDNode>(Op);
int FrameIdx = FrameIdxNode->getIndex();
return MFI->isFixedObjectIndex(FrameIdx) &&
MFI->getObjectOffset(FrameIdx) >= 0;
}
/// IsPossiblyOverwrittenArgumentOfTailCall - Check if the operand could
/// possibly be overwritten when lowering the outgoing arguments in a tail
/// call. Currently the implementation of this call is very conservative and
/// assumes all arguments sourcing from FORMAL_ARGUMENTS or a CopyFromReg with
/// virtual registers would be overwritten by direct lowering.
static bool IsPossiblyOverwrittenArgumentOfTailCall(SDValue Op,
MachineFrameInfo * MFI) {
RegisterSDNode * OpReg = NULL;
if (Op.getOpcode() == ISD::FORMAL_ARGUMENTS ||
(Op.getOpcode()== ISD::CopyFromReg &&
(OpReg = dyn_cast<RegisterSDNode>(Op.getOperand(1))) &&
(OpReg->getReg() >= TargetRegisterInfo::FirstVirtualRegister)) ||
(Op.getOpcode() == ISD::LOAD &&
IsFixedFrameObjectWithPosOffset(MFI, Op.getOperand(1))) ||
(Op.getOpcode() == ISD::MERGE_VALUES &&
Op.getOperand(Op.getResNo()).getOpcode() == ISD::LOAD &&
IsFixedFrameObjectWithPosOffset(MFI, Op.getOperand(Op.getResNo()).
getOperand(1))))
return true;
return false;
}
/// CheckDAGForTailCallsAndFixThem - This Function looks for CALL nodes in the
/// DAG and fixes their tailcall attribute operand.
static void CheckDAGForTailCallsAndFixThem(SelectionDAG &DAG,
TargetLowering& TLI) {
SDNode * Ret = NULL;
SDValue Terminator = DAG.getRoot();
// Find RET node.
if (Terminator.getOpcode() == ISD::RET) {
Ret = Terminator.getNode();
}
// Fix tail call attribute of CALL nodes.
for (SelectionDAG::allnodes_iterator BE = DAG.allnodes_begin(),
BI = DAG.allnodes_end(); BI != BE; ) {
--BI;
if (BI->getOpcode() == ISD::CALL) {
SDValue OpRet(Ret, 0);
SDValue OpCall(BI, 0);
bool isMarkedTailCall =
cast<ConstantSDNode>(OpCall.getOperand(3))->getValue() != 0;
// If CALL node has tail call attribute set to true and the call is not
// eligible (no RET or the target rejects) the attribute is fixed to
// false. The TargetLowering::IsEligibleForTailCallOptimization function
// must correctly identify tail call optimizable calls.
if (!isMarkedTailCall) continue;
if (Ret==NULL ||
!TLI.IsEligibleForTailCallOptimization(OpCall, OpRet, DAG)) {
// Not eligible. Mark CALL node as non tail call.
SmallVector<SDValue, 32> Ops;
unsigned idx=0;
for(SDNode::op_iterator I =OpCall.getNode()->op_begin(),
E = OpCall.getNode()->op_end(); I != E; I++, idx++) {
if (idx!=3)
Ops.push_back(*I);
else
Ops.push_back(DAG.getConstant(false, TLI.getPointerTy()));
}
DAG.UpdateNodeOperands(OpCall, Ops.begin(), Ops.size());
} else {
// Look for tail call clobbered arguments. Emit a series of
// copyto/copyfrom virtual register nodes to protect them.
SmallVector<SDValue, 32> Ops;
SDValue Chain = OpCall.getOperand(0), InFlag;
unsigned idx=0;
for(SDNode::op_iterator I = OpCall.getNode()->op_begin(),
E = OpCall.getNode()->op_end(); I != E; I++, idx++) {
SDValue Arg = *I;
if (idx > 4 && (idx % 2)) {
bool isByVal = cast<ARG_FLAGSSDNode>(OpCall.getOperand(idx+1))->
getArgFlags().isByVal();
MachineFunction &MF = DAG.getMachineFunction();
MachineFrameInfo *MFI = MF.getFrameInfo();
if (!isByVal &&
IsPossiblyOverwrittenArgumentOfTailCall(Arg, MFI)) {
MVT VT = Arg.getValueType();
unsigned VReg = MF.getRegInfo().
createVirtualRegister(TLI.getRegClassFor(VT));
Chain = DAG.getCopyToReg(Chain, VReg, Arg, InFlag);
InFlag = Chain.getValue(1);
Arg = DAG.getCopyFromReg(Chain, VReg, VT, InFlag);
Chain = Arg.getValue(1);
InFlag = Arg.getValue(2);
}
}
Ops.push_back(Arg);
}
// Link in chain of CopyTo/CopyFromReg.
Ops[0] = Chain;
DAG.UpdateNodeOperands(OpCall, Ops.begin(), Ops.size());
}
}
}
}
void SelectionDAGISel::SelectBasicBlock(BasicBlock *LLVMBB,
BasicBlock::iterator Begin,
BasicBlock::iterator End) {
SDL->setCurrentBasicBlock(BB);
MachineModuleInfo *MMI = CurDAG->getMachineModuleInfo();
if (MMI && BB->isLandingPad()) {
// Add a label to mark the beginning of the landing pad. Deletion of the
// landing pad can thus be detected via the MachineModuleInfo.
unsigned LabelID = MMI->addLandingPad(BB);
CurDAG->setRoot(CurDAG->getLabel(ISD::EH_LABEL,
CurDAG->getEntryNode(), LabelID));
// Mark exception register as live in.
unsigned Reg = TLI.getExceptionAddressRegister();
if (Reg) BB->addLiveIn(Reg);
// Mark exception selector register as live in.
Reg = TLI.getExceptionSelectorRegister();
if (Reg) BB->addLiveIn(Reg);
// FIXME: Hack around an exception handling flaw (PR1508): the personality
// function and list of typeids logically belong to the invoke (or, if you
// like, the basic block containing the invoke), and need to be associated
// with it in the dwarf exception handling tables. Currently however the
// information is provided by an intrinsic (eh.selector) that can be moved
// to unexpected places by the optimizers: if the unwind edge is critical,
// then breaking it can result in the intrinsics being in the successor of
// the landing pad, not the landing pad itself. This results in exceptions
// not being caught because no typeids are associated with the invoke.
// This may not be the only way things can go wrong, but it is the only way
// we try to work around for the moment.
BranchInst *Br = dyn_cast<BranchInst>(LLVMBB->getTerminator());
if (Br && Br->isUnconditional()) { // Critical edge?
BasicBlock::iterator I, E;
for (I = LLVMBB->begin(), E = --LLVMBB->end(); I != E; ++I)
if (isa<EHSelectorInst>(I))
break;
if (I == E)
// No catch info found - try to extract some from the successor.
copyCatchInfo(Br->getSuccessor(0), LLVMBB, MMI, *FuncInfo);
}
}
// Lower all of the non-terminator instructions.
for (BasicBlock::iterator I = Begin; I != End; ++I)
if (!isa<TerminatorInst>(I))
SDL->visit(*I);
// Ensure that all instructions which are used outside of their defining
// blocks are available as virtual registers. Invoke is handled elsewhere.
for (BasicBlock::iterator I = Begin; I != End; ++I)
if (!I->use_empty() && !isa<PHINode>(I) && !isa<InvokeInst>(I)) {
DenseMap<const Value*,unsigned>::iterator VMI =FuncInfo->ValueMap.find(I);
if (VMI != FuncInfo->ValueMap.end())
SDL->CopyValueToVirtualRegister(I, VMI->second);
}
// Handle PHI nodes in successor blocks.
if (End == LLVMBB->end()) {
HandlePHINodesInSuccessorBlocks(LLVMBB);
// Lower the terminator after the copies are emitted.
SDL->visit(*LLVMBB->getTerminator());
}
// Make sure the root of the DAG is up-to-date.
CurDAG->setRoot(SDL->getControlRoot());
// Check whether calls in this block are real tail calls. Fix up CALL nodes
// with correct tailcall attribute so that the target can rely on the tailcall
// attribute indicating whether the call is really eligible for tail call
// optimization.
CheckDAGForTailCallsAndFixThem(*CurDAG, TLI);
// Final step, emit the lowered DAG as machine code.
CodeGenAndEmitDAG();
SDL->clear();
}
void SelectionDAGISel::ComputeLiveOutVRegInfo() {
SmallPtrSet<SDNode*, 128> VisitedNodes;
SmallVector<SDNode*, 128> Worklist;
Worklist.push_back(CurDAG->getRoot().getNode());
APInt Mask;
APInt KnownZero;
APInt KnownOne;
while (!Worklist.empty()) {
SDNode *N = Worklist.back();
Worklist.pop_back();
// If we've already seen this node, ignore it.
if (!VisitedNodes.insert(N))
continue;
// 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)
Worklist.push_back(N->getOperand(i).getNode());
// If this is a CopyToReg with a vreg dest, process it.
if (N->getOpcode() != ISD::CopyToReg)
continue;
unsigned DestReg = cast<RegisterSDNode>(N->getOperand(1))->getReg();
if (!TargetRegisterInfo::isVirtualRegister(DestReg))
continue;
// Ignore non-scalar or non-integer values.
SDValue Src = N->getOperand(2);
MVT SrcVT = Src.getValueType();
if (!SrcVT.isInteger() || SrcVT.isVector())
continue;
unsigned NumSignBits = CurDAG->ComputeNumSignBits(Src);
Mask = APInt::getAllOnesValue(SrcVT.getSizeInBits());
CurDAG->ComputeMaskedBits(Src, Mask, KnownZero, KnownOne);
// Only install this information if it tells us something.
if (NumSignBits != 1 || KnownZero != 0 || KnownOne != 0) {
DestReg -= TargetRegisterInfo::FirstVirtualRegister;
FunctionLoweringInfo &FLI = CurDAG->getFunctionLoweringInfo();
if (DestReg >= FLI.LiveOutRegInfo.size())
FLI.LiveOutRegInfo.resize(DestReg+1);
FunctionLoweringInfo::LiveOutInfo &LOI = FLI.LiveOutRegInfo[DestReg];
LOI.NumSignBits = NumSignBits;
LOI.KnownOne = NumSignBits;
LOI.KnownZero = NumSignBits;
}
}
}
void SelectionDAGISel::CodeGenAndEmitDAG() {
std::string GroupName;
if (TimePassesIsEnabled)
GroupName = "Instruction Selection and Scheduling";
std::string BlockName;
if (ViewDAGCombine1 || ViewLegalizeTypesDAGs || ViewLegalizeDAGs ||
ViewDAGCombine2 || ViewISelDAGs || ViewSchedDAGs || ViewSUnitDAGs)
BlockName = CurDAG->getMachineFunction().getFunction()->getName() + ':' +
BB->getBasicBlock()->getName();
DOUT << "Initial selection DAG:\n";
DEBUG(CurDAG->dump());
if (ViewDAGCombine1) CurDAG->viewGraph("dag-combine1 input for " + BlockName);
// Run the DAG combiner in pre-legalize mode.
if (TimePassesIsEnabled) {
NamedRegionTimer T("DAG Combining 1", GroupName);
CurDAG->Combine(false, *AA, Fast);
} else {
CurDAG->Combine(false, *AA, Fast);
}
DOUT << "Optimized lowered selection DAG:\n";
DEBUG(CurDAG->dump());
// Second step, hack on the DAG until it only uses operations and types that
// the target supports.
if (EnableLegalizeTypes) {// Enable this some day.
if (ViewLegalizeTypesDAGs) CurDAG->viewGraph("legalize-types input for " +
BlockName);
if (TimePassesIsEnabled) {
NamedRegionTimer T("Type Legalization", GroupName);
CurDAG->LegalizeTypes();
} else {
CurDAG->LegalizeTypes();
}
DOUT << "Type-legalized selection DAG:\n";
DEBUG(CurDAG->dump());
// TODO: enable a dag combine pass here.
}
if (ViewLegalizeDAGs) CurDAG->viewGraph("legalize input for " + BlockName);
if (TimePassesIsEnabled) {
NamedRegionTimer T("DAG Legalization", GroupName);
CurDAG->Legalize();
} else {
CurDAG->Legalize();
}
DOUT << "Legalized selection DAG:\n";
DEBUG(CurDAG->dump());
if (ViewDAGCombine2) CurDAG->viewGraph("dag-combine2 input for " + BlockName);
// Run the DAG combiner in post-legalize mode.
if (TimePassesIsEnabled) {
NamedRegionTimer T("DAG Combining 2", GroupName);
CurDAG->Combine(true, *AA, Fast);
} else {
CurDAG->Combine(true, *AA, Fast);
}
DOUT << "Optimized legalized selection DAG:\n";
DEBUG(CurDAG->dump());
if (ViewISelDAGs) CurDAG->viewGraph("isel input for " + BlockName);
if (!Fast && EnableValueProp)
ComputeLiveOutVRegInfo();
// Third, instruction select all of the operations to machine code, adding the
// code to the MachineBasicBlock.
if (TimePassesIsEnabled) {
NamedRegionTimer T("Instruction Selection", GroupName);
InstructionSelect();
} else {
InstructionSelect();
}
DOUT << "Selected selection DAG:\n";
DEBUG(CurDAG->dump());
if (ViewSchedDAGs) CurDAG->viewGraph("scheduler input for " + BlockName);
// Schedule machine code.
ScheduleDAG *Scheduler;
if (TimePassesIsEnabled) {
NamedRegionTimer T("Instruction Scheduling", GroupName);
Scheduler = Schedule();
} else {
Scheduler = Schedule();
}
if (ViewSUnitDAGs) Scheduler->viewGraph();
// Emit machine code to BB. This can change 'BB' to the last block being
// inserted into.
if (TimePassesIsEnabled) {
NamedRegionTimer T("Instruction Creation", GroupName);
BB = Scheduler->EmitSchedule();
} else {
BB = Scheduler->EmitSchedule();
}
// Free the scheduler state.
if (TimePassesIsEnabled) {
NamedRegionTimer T("Instruction Scheduling Cleanup", GroupName);
delete Scheduler;
} else {
delete Scheduler;
}
DOUT << "Selected machine code:\n";
DEBUG(BB->dump());
}
void SelectionDAGISel::SelectAllBasicBlocks(Function &Fn, MachineFunction &MF) {
for (Function::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I) {
BasicBlock *LLVMBB = &*I;
BB = FuncInfo->MBBMap[LLVMBB];
BasicBlock::iterator const Begin = LLVMBB->begin();
BasicBlock::iterator const End = LLVMBB->end();
BasicBlock::iterator I = Begin;
// Lower any arguments needed in this block if this is the entry block.
if (LLVMBB == &Fn.getEntryBlock())
LowerArguments(LLVMBB);
// Before doing SelectionDAG ISel, see if FastISel has been requested.
// FastISel doesn't support EH landing pads, which require special handling.
if (EnableFastISel && !BB->isLandingPad()) {
if (FastISel *F = TLI.createFastISel(*FuncInfo->MF, FuncInfo->ValueMap,
FuncInfo->MBBMap)) {
// Emit code for any incoming arguments. This must happen before
// beginning FastISel on the entry block.
if (LLVMBB == &Fn.getEntryBlock()) {
CurDAG->setRoot(SDL->getControlRoot());
CodeGenAndEmitDAG();
SDL->clear();
}
F->setCurrentBlock(BB);
// Do FastISel on as many instructions as possible.
for (; I != End; ++I) {
// Just before the terminator instruction, insert instructions to
// feed PHI nodes in successor blocks.
if (isa<TerminatorInst>(I))
if (!HandlePHINodesInSuccessorBlocksFast(LLVMBB, F)) {
if (DisableFastISelAbort)
break;
#ifndef NDEBUG
I->dump();
#endif
assert(0 && "FastISel didn't handle a PHI in a successor");
}
// First try normal tablegen-generated "fast" selection.
if (F->SelectInstruction(I))
continue;
// Next, try calling the target to attempt to handle the instruction.
if (F->TargetSelectInstruction(I))
continue;
// Then handle certain instructions as single-LLVM-Instruction blocks.
if (isa<CallInst>(I) || isa<LoadInst>(I) ||
isa<StoreInst>(I)) {
if (I->getType() != Type::VoidTy) {
unsigned &R = FuncInfo->ValueMap[I];
if (!R)
R = FuncInfo->CreateRegForValue(I);
}
SelectBasicBlock(LLVMBB, I, next(I));
continue;
}
if (!DisableFastISelAbort &&
// For now, don't abort on non-conditional-branch terminators.
(!isa<TerminatorInst>(I) ||
(isa<BranchInst>(I) &&
cast<BranchInst>(I)->isUnconditional()))) {
// The "fast" selector couldn't handle something and bailed.
// For the purpose of debugging, just abort.
#ifndef NDEBUG
I->dump();
#endif
assert(0 && "FastISel didn't select the entire block");
}
break;
}
delete F;
}
}
// Run SelectionDAG instruction selection on the remainder of the block
// not handled by FastISel. If FastISel is not run, this is the entire
// block.
if (I != End)
SelectBasicBlock(LLVMBB, I, End);
FinishBasicBlock();
}
}
void
SelectionDAGISel::FinishBasicBlock() {
// Perform target specific isel post processing.
InstructionSelectPostProcessing();
DOUT << "Target-post-processed machine code:\n";
DEBUG(BB->dump());
DOUT << "Total amount of phi nodes to update: "
<< SDL->PHINodesToUpdate.size() << "\n";
DEBUG(for (unsigned i = 0, e = SDL->PHINodesToUpdate.size(); i != e; ++i)
DOUT << "Node " << i << " : (" << SDL->PHINodesToUpdate[i].first
<< ", " << SDL->PHINodesToUpdate[i].second << ")\n";);
// Next, now that we know what the last MBB the LLVM BB expanded is, update
// PHI nodes in successors.
if (SDL->SwitchCases.empty() &&
SDL->JTCases.empty() &&
SDL->BitTestCases.empty()) {
for (unsigned i = 0, e = SDL->PHINodesToUpdate.size(); i != e; ++i) {
MachineInstr *PHI = SDL->PHINodesToUpdate[i].first;
assert(PHI->getOpcode() == TargetInstrInfo::PHI &&
"This is not a machine PHI node that we are updating!");
PHI->addOperand(MachineOperand::CreateReg(SDL->PHINodesToUpdate[i].second,
false));
PHI->addOperand(MachineOperand::CreateMBB(BB));
}
SDL->PHINodesToUpdate.clear();
return;
}
for (unsigned i = 0, e = SDL->BitTestCases.size(); i != e; ++i) {
// Lower header first, if it wasn't already lowered
if (!SDL->BitTestCases[i].Emitted) {
// Set the current basic block to the mbb we wish to insert the code into
BB = SDL->BitTestCases[i].Parent;
SDL->setCurrentBasicBlock(BB);
// Emit the code
SDL->visitBitTestHeader(SDL->BitTestCases[i]);
CurDAG->setRoot(SDL->getRoot());
CodeGenAndEmitDAG();
SDL->clear();
}
for (unsigned j = 0, ej = SDL->BitTestCases[i].Cases.size(); j != ej; ++j) {
// Set the current basic block to the mbb we wish to insert the code into
BB = SDL->BitTestCases[i].Cases[j].ThisBB;
SDL->setCurrentBasicBlock(BB);
// Emit the code
if (j+1 != ej)
SDL->visitBitTestCase(SDL->BitTestCases[i].Cases[j+1].ThisBB,
SDL->BitTestCases[i].Reg,
SDL->BitTestCases[i].Cases[j]);
else
SDL->visitBitTestCase(SDL->BitTestCases[i].Default,
SDL->BitTestCases[i].Reg,
SDL->BitTestCases[i].Cases[j]);
CurDAG->setRoot(SDL->getRoot());
CodeGenAndEmitDAG();
SDL->clear();
}
// Update PHI Nodes
for (unsigned pi = 0, pe = SDL->PHINodesToUpdate.size(); pi != pe; ++pi) {
MachineInstr *PHI = SDL->PHINodesToUpdate[pi].first;
MachineBasicBlock *PHIBB = PHI->getParent();
assert(PHI->getOpcode() == TargetInstrInfo::PHI &&
"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 == SDL->BitTestCases[i].Default) {
PHI->addOperand(MachineOperand::CreateReg(SDL->PHINodesToUpdate[pi].second,
false));
PHI->addOperand(MachineOperand::CreateMBB(SDL->BitTestCases[i].Parent));
PHI->addOperand(MachineOperand::CreateReg(SDL->PHINodesToUpdate[pi].second,
false));
PHI->addOperand(MachineOperand::CreateMBB(SDL->BitTestCases[i].Cases.
back().ThisBB));
}
// One of "cases" BB.
for (unsigned j = 0, ej = SDL->BitTestCases[i].Cases.size();
j != ej; ++j) {
MachineBasicBlock* cBB = SDL->BitTestCases[i].Cases[j].ThisBB;
if (cBB->succ_end() !=
std::find(cBB->succ_begin(),cBB->succ_end(), PHIBB)) {
PHI->addOperand(MachineOperand::CreateReg(SDL->PHINodesToUpdate[pi].second,
false));
PHI->addOperand(MachineOperand::CreateMBB(cBB));
}
}
}
}
SDL->BitTestCases.clear();
// 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 = SDL->JTCases.size(); i != e; ++i) {
// Lower header first, if it wasn't already lowered
if (!SDL->JTCases[i].first.Emitted) {
// Set the current basic block to the mbb we wish to insert the code into
BB = SDL->JTCases[i].first.HeaderBB;
SDL->setCurrentBasicBlock(BB);
// Emit the code
SDL->visitJumpTableHeader(SDL->JTCases[i].second, SDL->JTCases[i].first);
CurDAG->setRoot(SDL->getRoot());
CodeGenAndEmitDAG();
SDL->clear();
}
// Set the current basic block to the mbb we wish to insert the code into
BB = SDL->JTCases[i].second.MBB;
SDL->setCurrentBasicBlock(BB);
// Emit the code
SDL->visitJumpTable(SDL->JTCases[i].second);
CurDAG->setRoot(SDL->getRoot());
CodeGenAndEmitDAG();
SDL->clear();
// Update PHI Nodes
for (unsigned pi = 0, pe = SDL->PHINodesToUpdate.size(); pi != pe; ++pi) {
MachineInstr *PHI = SDL->PHINodesToUpdate[pi].first;
MachineBasicBlock *PHIBB = PHI->getParent();
assert(PHI->getOpcode() == TargetInstrInfo::PHI &&
"This is not a machine PHI node that we are updating!");
// "default" BB. We can go there only from header BB.
if (PHIBB == SDL->JTCases[i].second.Default) {
PHI->addOperand(MachineOperand::CreateReg(SDL->PHINodesToUpdate[pi].second,
false));
PHI->addOperand(MachineOperand::CreateMBB(SDL->JTCases[i].first.HeaderBB));
}
// JT BB. Just iterate over successors here
if (BB->succ_end() != std::find(BB->succ_begin(),BB->succ_end(), PHIBB)) {
PHI->addOperand(MachineOperand::CreateReg(SDL->PHINodesToUpdate[pi].second,
false));
PHI->addOperand(MachineOperand::CreateMBB(BB));
}
}
}
SDL->JTCases.clear();
// 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 = SDL->PHINodesToUpdate.size(); i != e; ++i) {
MachineInstr *PHI = SDL->PHINodesToUpdate[i].first;
assert(PHI->getOpcode() == TargetInstrInfo::PHI &&
"This is not a machine PHI node that we are updating!");
if (BB->isSuccessor(PHI->getParent())) {
PHI->addOperand(MachineOperand::CreateReg(SDL->PHINodesToUpdate[i].second,
false));
PHI->addOperand(MachineOperand::CreateMBB(BB));
}
}
// If we generated any switch lowering information, build and codegen any
// additional DAGs necessary.
for (unsigned i = 0, e = SDL->SwitchCases.size(); i != e; ++i) {
// Set the current basic block to the mbb we wish to insert the code into
BB = SDL->SwitchCases[i].ThisBB;
SDL->setCurrentBasicBlock(BB);
// Emit the code
SDL->visitSwitchCase(SDL->SwitchCases[i]);
CurDAG->setRoot(SDL->getRoot());
CodeGenAndEmitDAG();
SDL->clear();
// 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.
while ((BB = SDL->SwitchCases[i].TrueBB)) { // Handle LHS and RHS.
for (MachineBasicBlock::iterator Phi = BB->begin();
Phi != BB->end() && Phi->getOpcode() == TargetInstrInfo::PHI; ++Phi){
// This value for this PHI node is recorded in PHINodesToUpdate, get it.
for (unsigned pn = 0; ; ++pn) {
assert(pn != SDL->PHINodesToUpdate.size() &&
"Didn't find PHI entry!");
if (SDL->PHINodesToUpdate[pn].first == Phi) {
Phi->addOperand(MachineOperand::CreateReg(SDL->PHINodesToUpdate[pn].
second, false));
Phi->addOperand(MachineOperand::CreateMBB(SDL->SwitchCases[i].ThisBB));
break;
}
}
}
// Don't process RHS if same block as LHS.
if (BB == SDL->SwitchCases[i].FalseBB)
SDL->SwitchCases[i].FalseBB = 0;
// If we haven't handled the RHS, do so now. Otherwise, we're done.
SDL->SwitchCases[i].TrueBB = SDL->SwitchCases[i].FalseBB;
SDL->SwitchCases[i].FalseBB = 0;
}
assert(SDL->SwitchCases[i].TrueBB == 0 && SDL->SwitchCases[i].FalseBB == 0);
}
SDL->SwitchCases.clear();
SDL->PHINodesToUpdate.clear();
}
/// Schedule - Pick a safe ordering for instructions for each
/// target node in the graph.
///
ScheduleDAG *SelectionDAGISel::Schedule() {
RegisterScheduler::FunctionPassCtor Ctor = RegisterScheduler::getDefault();
if (!Ctor) {
Ctor = ISHeuristic;
RegisterScheduler::setDefault(Ctor);
}
ScheduleDAG *Scheduler = Ctor(this, CurDAG, BB, Fast);
Scheduler->Run();
return Scheduler;
}
HazardRecognizer *SelectionDAGISel::CreateTargetHazardRecognizer() {
return new HazardRecognizer();
}
//===----------------------------------------------------------------------===//
// 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, NeededMask, 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[0]); // input chain.
Ops.push_back(InOps[1]); // input asm string.
unsigned i = 2, e = InOps.size();
if (InOps[e-1].getValueType() == MVT::Flag)
--e; // Don't process a flag operand if it is here.
while (i != e) {
unsigned Flags = cast<ConstantSDNode>(InOps[i])->getValue();
if ((Flags & 7) != 4 /*MEM*/) {
// Just skip over this operand, copying the operands verbatim.
Ops.insert(Ops.end(), InOps.begin()+i, InOps.begin()+i+(Flags >> 3) + 1);
i += (Flags >> 3) + 1;
} else {
assert((Flags >> 3) == 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)) {
cerr << "Could not match memory address. Inline asm failure!\n";
exit(1);
}
// Add this to the output node.
MVT IntPtrTy = CurDAG->getTargetLoweringInfo().getPointerTy();
Ops.push_back(CurDAG->getTargetConstant(4/*MEM*/ | (SelOps.size() << 3),
IntPtrTy));
Ops.insert(Ops.end(), SelOps.begin(), SelOps.end());
i += 2;
}
}
// Add the flag input back if present.
if (e != InOps.size())
Ops.push_back(InOps.back());
}
char SelectionDAGISel::ID = 0;
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