llvm-6502/utils/TableGen/InstrSelectorEmitter.cpp

1297 lines
50 KiB
C++
Raw Normal View History

//===- InstrInfoEmitter.cpp - Generate a Instruction Set Desc. ------------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This tablegen backend is responsible for emitting a description of the target
// instruction set for the code generator.
//
//===----------------------------------------------------------------------===//
#include "InstrSelectorEmitter.h"
#include "Record.h"
#include "llvm/Support/Debug.h"
#include "llvm/ADT/StringExtras.h"
#include <set>
using namespace llvm;
NodeType::ArgResultTypes NodeType::Translate(Record *R) {
const std::string &Name = R->getName();
if (Name == "DNVT_any") return Any;
if (Name == "DNVT_void") return Void;
if (Name == "DNVT_val" ) return Val;
if (Name == "DNVT_arg0") return Arg0;
if (Name == "DNVT_arg1") return Arg1;
if (Name == "DNVT_ptr" ) return Ptr;
if (Name == "DNVT_i8" ) return I8;
throw "Unknown DagNodeValType '" + Name + "'!";
}
//===----------------------------------------------------------------------===//
// TreePatternNode implementation
//
/// getValueRecord - Returns the value of this tree node as a record. For now
/// we only allow DefInit's as our leaf values, so this is used.
Record *TreePatternNode::getValueRecord() const {
DefInit *DI = dynamic_cast<DefInit*>(getValue());
assert(DI && "Instruction Selector does not yet support non-def leaves!");
return DI->getDef();
}
// updateNodeType - Set the node type of N to VT if VT contains information. If
// N already contains a conflicting type, then throw an exception
//
bool TreePatternNode::updateNodeType(MVT::ValueType VT,
const std::string &RecName) {
if (VT == MVT::Other || getType() == VT) return false;
if (getType() == MVT::Other) {
setType(VT);
return true;
}
throw "Type inference contradiction found for pattern " + RecName;
}
/// InstantiateNonterminals - If this pattern refers to any nonterminals which
/// are not themselves completely resolved, clone the nonterminal and resolve it
/// with the using context we provide.
///
void TreePatternNode::InstantiateNonterminals(InstrSelectorEmitter &ISE) {
if (!isLeaf()) {
for (unsigned i = 0, e = getNumChildren(); i != e; ++i)
getChild(i)->InstantiateNonterminals(ISE);
return;
}
// If this is a leaf, it might be a reference to a nonterminal! Check now.
Record *R = getValueRecord();
if (R->isSubClassOf("Nonterminal")) {
Pattern *NT = ISE.getPattern(R);
if (!NT->isResolved()) {
// We found an unresolved nonterminal reference. Ask the ISE to clone
// it for us, then update our reference to the fresh, new, resolved,
// nonterminal.
Value = new DefInit(ISE.InstantiateNonterminal(NT, getType()));
}
}
}
/// clone - Make a copy of this tree and all of its children.
///
TreePatternNode *TreePatternNode::clone() const {
TreePatternNode *New;
if (isLeaf()) {
New = new TreePatternNode(Value);
} else {
std::vector<std::pair<TreePatternNode*, std::string> > CChildren;
CChildren.reserve(Children.size());
for (unsigned i = 0, e = getNumChildren(); i != e; ++i)
CChildren.push_back(std::make_pair(getChild(i)->clone(),getChildName(i)));
New = new TreePatternNode(Operator, CChildren);
}
New->setType(Type);
return New;
}
std::ostream &llvm::operator<<(std::ostream &OS, const TreePatternNode &N) {
if (N.isLeaf())
return OS << N.getType() << ":" << *N.getValue();
OS << "(" << N.getType() << ":";
OS << N.getOperator()->getName();
if (N.getNumChildren() != 0) {
OS << " " << *N.getChild(0);
for (unsigned i = 1, e = N.getNumChildren(); i != e; ++i)
OS << ", " << *N.getChild(i);
}
return OS << ")";
}
void TreePatternNode::dump() const { std::cerr << *this; }
//===----------------------------------------------------------------------===//
// Pattern implementation
//
// Parse the specified DagInit into a TreePattern which we can use.
//
Pattern::Pattern(PatternType pty, DagInit *RawPat, Record *TheRec,
InstrSelectorEmitter &ise)
: PTy(pty), ResultNode(0), TheRecord(TheRec), ISE(ise) {
// First, parse the pattern...
Tree = ParseTreePattern(RawPat);
// Run the type-inference engine...
InferAllTypes();
if (PTy == Instruction || PTy == Expander) {
// Check to make sure there is not any unset types in the tree pattern...
if (!isResolved()) {
std::cerr << "In pattern: " << *Tree << "\n";
error("Could not infer all types!");
}
// Check to see if we have a top-level (set) of a register.
if (Tree->getOperator()->getName() == "set") {
assert(Tree->getNumChildren() == 2 && "Set with != 2 arguments?");
if (!Tree->getChild(0)->isLeaf())
error("Arg #0 of set should be a register or register class!");
ResultNode = Tree->getChild(0);
ResultName = Tree->getChildName(0);
Tree = Tree->getChild(1);
}
}
calculateArgs(Tree, "");
}
void Pattern::error(const std::string &Msg) const {
std::string M = "In ";
switch (PTy) {
case Nonterminal: M += "nonterminal "; break;
case Instruction: M += "instruction "; break;
case Expander : M += "expander "; break;
}
throw M + TheRecord->getName() + ": " + Msg;
}
/// calculateArgs - Compute the list of all of the arguments to this pattern,
/// which are the non-void leaf nodes in this pattern.
///
void Pattern::calculateArgs(TreePatternNode *N, const std::string &Name) {
if (N->isLeaf() || N->getNumChildren() == 0) {
if (N->getType() != MVT::isVoid)
Args.push_back(std::make_pair(N, Name));
} else {
for (unsigned i = 0, e = N->getNumChildren(); i != e; ++i)
calculateArgs(N->getChild(i), N->getChildName(i));
}
}
/// getIntrinsicType - Check to see if the specified record has an intrinsic
/// type which should be applied to it. This infer the type of register
/// references from the register file information, for example.
///
MVT::ValueType Pattern::getIntrinsicType(Record *R) const {
// Check to see if this is a register or a register class...
if (R->isSubClassOf("RegisterClass"))
return getValueType(R->getValueAsDef("RegType"));
else if (R->isSubClassOf("Nonterminal"))
return ISE.ReadNonterminal(R)->getTree()->getType();
else if (R->isSubClassOf("Register")) {
std::cerr << "WARNING: Explicit registers not handled yet!\n";
return MVT::Other;
}
error("Unknown value used: " + R->getName());
return MVT::Other;
}
TreePatternNode *Pattern::ParseTreePattern(DagInit *Dag) {
Record *Operator = Dag->getNodeType();
if (Operator->isSubClassOf("ValueType")) {
// If the operator is a ValueType, then this must be "type cast" of a leaf
// node.
if (Dag->getNumArgs() != 1)
error("Type cast only valid for a leaf node!");
Init *Arg = Dag->getArg(0);
TreePatternNode *New;
if (DefInit *DI = dynamic_cast<DefInit*>(Arg)) {
New = new TreePatternNode(DI);
// If it's a regclass or something else known, set the type.
New->setType(getIntrinsicType(DI->getDef()));
} else if (DagInit *DI = dynamic_cast<DagInit*>(Arg)) {
New = ParseTreePattern(DI);
} else {
Arg->dump();
error("Unknown leaf value for tree pattern!");
return 0;
}
// Apply the type cast...
New->updateNodeType(getValueType(Operator), TheRecord->getName());
return New;
}
if (!ISE.getNodeTypes().count(Operator))
error("Unrecognized node '" + Operator->getName() + "'!");
std::vector<std::pair<TreePatternNode*, std::string> > Children;
for (unsigned i = 0, e = Dag->getNumArgs(); i != e; ++i) {
Init *Arg = Dag->getArg(i);
if (DagInit *DI = dynamic_cast<DagInit*>(Arg)) {
Children.push_back(std::make_pair(ParseTreePattern(DI),
Dag->getArgName(i)));
} else if (DefInit *DefI = dynamic_cast<DefInit*>(Arg)) {
Record *R = DefI->getDef();
// Direct reference to a leaf DagNode? Turn it into a DagNode if its own.
if (R->isSubClassOf("DagNode")) {
Dag->setArg(i, new DagInit(R,
std::vector<std::pair<Init*, std::string> >()));
--i; // Revisit this node...
} else {
Children.push_back(std::make_pair(new TreePatternNode(DefI),
Dag->getArgName(i)));
// If it's a regclass or something else known, set the type.
Children.back().first->setType(getIntrinsicType(R));
}
} else {
Arg->dump();
error("Unknown leaf value for tree pattern!");
}
}
return new TreePatternNode(Operator, Children);
}
void Pattern::InferAllTypes() {
bool MadeChange, AnyUnset;
do {
MadeChange = false;
AnyUnset = InferTypes(Tree, MadeChange);
} while ((AnyUnset || MadeChange) && !(AnyUnset && !MadeChange));
Resolved = !AnyUnset;
}
// InferTypes - Perform type inference on the tree, returning true if there
// are any remaining untyped nodes and setting MadeChange if any changes were
// made.
bool Pattern::InferTypes(TreePatternNode *N, bool &MadeChange) {
if (N->isLeaf()) return N->getType() == MVT::Other;
bool AnyUnset = false;
Record *Operator = N->getOperator();
const NodeType &NT = ISE.getNodeType(Operator);
// Check to see if we can infer anything about the argument types from the
// return types...
if (N->getNumChildren() != NT.ArgTypes.size())
error("Incorrect number of children for " + Operator->getName() + " node!");
for (unsigned i = 0, e = N->getNumChildren(); i != e; ++i) {
TreePatternNode *Child = N->getChild(i);
AnyUnset |= InferTypes(Child, MadeChange);
switch (NT.ArgTypes[i]) {
case NodeType::Any: break;
case NodeType::I8:
MadeChange |= Child->updateNodeType(MVT::i1, TheRecord->getName());
break;
case NodeType::Arg0:
MadeChange |= Child->updateNodeType(N->getChild(0)->getType(),
TheRecord->getName());
break;
case NodeType::Arg1:
MadeChange |= Child->updateNodeType(N->getChild(1)->getType(),
TheRecord->getName());
break;
case NodeType::Val:
if (Child->getType() == MVT::isVoid)
error("Inferred a void node in an illegal place!");
break;
case NodeType::Ptr:
MadeChange |= Child->updateNodeType(ISE.getTarget().getPointerType(),
TheRecord->getName());
break;
case NodeType::Void:
MadeChange |= Child->updateNodeType(MVT::isVoid, TheRecord->getName());
break;
default: assert(0 && "Invalid argument ArgType!");
}
}
// See if we can infer anything about the return type now...
switch (NT.ResultType) {
case NodeType::Any: break;
case NodeType::Void:
MadeChange |= N->updateNodeType(MVT::isVoid, TheRecord->getName());
break;
case NodeType::I8:
MadeChange |= N->updateNodeType(MVT::i1, TheRecord->getName());
break;
case NodeType::Arg0:
MadeChange |= N->updateNodeType(N->getChild(0)->getType(),
TheRecord->getName());
break;
case NodeType::Arg1:
MadeChange |= N->updateNodeType(N->getChild(1)->getType(),
TheRecord->getName());
break;
case NodeType::Ptr:
MadeChange |= N->updateNodeType(ISE.getTarget().getPointerType(),
TheRecord->getName());
break;
case NodeType::Val:
if (N->getType() == MVT::isVoid)
error("Inferred a void node in an illegal place!");
break;
default:
assert(0 && "Unhandled type constraint!");
break;
}
return AnyUnset | (N->getType() == MVT::Other);
}
/// clone - This method is used to make an exact copy of the current pattern,
/// then change the "TheRecord" instance variable to the specified record.
///
Pattern *Pattern::clone(Record *R) const {
assert(PTy == Nonterminal && "Can only clone nonterminals");
return new Pattern(Tree->clone(), R, Resolved, ISE);
}
std::ostream &llvm::operator<<(std::ostream &OS, const Pattern &P) {
switch (P.getPatternType()) {
case Pattern::Nonterminal: OS << "Nonterminal pattern "; break;
case Pattern::Instruction: OS << "Instruction pattern "; break;
case Pattern::Expander: OS << "Expander pattern "; break;
}
OS << P.getRecord()->getName() << ":\t";
if (Record *Result = P.getResult())
OS << Result->getName() << " = ";
OS << *P.getTree();
if (!P.isResolved())
OS << " [not completely resolved]";
return OS;
}
void Pattern::dump() const { std::cerr << *this; }
/// getSlotName - If this is a leaf node, return the slot name that the operand
/// will update.
std::string Pattern::getSlotName() const {
if (getPatternType() == Pattern::Nonterminal) {
// Just use the nonterminal name, which will already include the type if
// it has been cloned.
return getRecord()->getName();
} else {
std::string SlotName;
if (getResult())
SlotName = getResult()->getName()+"_";
else
SlotName = "Void_";
return SlotName + getName(getTree()->getType());
}
}
/// getSlotName - If this is a leaf node, return the slot name that the
/// operand will update.
std::string Pattern::getSlotName(Record *R) {
if (R->isSubClassOf("Nonterminal")) {
// Just use the nonterminal name, which will already include the type if
// it has been cloned.
return R->getName();
} else if (R->isSubClassOf("RegisterClass")) {
MVT::ValueType Ty = getValueType(R->getValueAsDef("RegType"));
return R->getName() + "_" + getName(Ty);
} else {
assert(0 && "Don't know how to get a slot name for this!");
}
return "";
}
//===----------------------------------------------------------------------===//
// PatternOrganizer implementation
//
/// addPattern - Add the specified pattern to the appropriate location in the
/// collection.
void PatternOrganizer::addPattern(Pattern *P) {
NodesForSlot &Nodes = AllPatterns[P->getSlotName()];
if (!P->getTree()->isLeaf())
Nodes[P->getTree()->getOperator()].push_back(P);
else {
// Right now we only support DefInit's with node types...
Nodes[P->getTree()->getValueRecord()].push_back(P);
}
}
//===----------------------------------------------------------------------===//
// InstrSelectorEmitter implementation
//
/// ReadNodeTypes - Read in all of the node types in the current RecordKeeper,
/// turning them into the more accessible NodeTypes data structure.
///
void InstrSelectorEmitter::ReadNodeTypes() {
std::vector<Record*> Nodes = Records.getAllDerivedDefinitions("DagNode");
DEBUG(std::cerr << "Getting node types: ");
for (unsigned i = 0, e = Nodes.size(); i != e; ++i) {
Record *Node = Nodes[i];
// Translate the return type...
NodeType::ArgResultTypes RetTy =
NodeType::Translate(Node->getValueAsDef("RetType"));
// Translate the arguments...
ListInit *Args = Node->getValueAsListInit("ArgTypes");
std::vector<NodeType::ArgResultTypes> ArgTypes;
for (unsigned a = 0, e = Args->getSize(); a != e; ++a) {
if (DefInit *DI = dynamic_cast<DefInit*>(Args->getElement(a)))
ArgTypes.push_back(NodeType::Translate(DI->getDef()));
else
throw "In node " + Node->getName() + ", argument is not a Def!";
if (a == 0 && ArgTypes.back() == NodeType::Arg0)
throw "In node " + Node->getName() + ", arg 0 cannot have type 'arg0'!";
if (a == 1 && ArgTypes.back() == NodeType::Arg1)
throw "In node " + Node->getName() + ", arg 1 cannot have type 'arg1'!";
}
if ((RetTy == NodeType::Arg0 && Args->getSize() == 0) ||
(RetTy == NodeType::Arg1 && Args->getSize() < 2))
throw "In node " + Node->getName() +
", invalid return type for node with this many operands!";
// Add the node type mapping now...
NodeTypes[Node] = NodeType(RetTy, ArgTypes);
DEBUG(std::cerr << Node->getName() << ", ");
}
DEBUG(std::cerr << "DONE!\n");
}
Pattern *InstrSelectorEmitter::ReadNonterminal(Record *R) {
Pattern *&P = Patterns[R];
if (P) return P; // Don't reread it!
DagInit *DI = R->getValueAsDag("Pattern");
P = new Pattern(Pattern::Nonterminal, DI, R, *this);
DEBUG(std::cerr << "Parsed " << *P << "\n");
return P;
}
// ReadNonTerminals - Read in all nonterminals and incorporate them into our
// pattern database.
void InstrSelectorEmitter::ReadNonterminals() {
std::vector<Record*> NTs = Records.getAllDerivedDefinitions("Nonterminal");
for (unsigned i = 0, e = NTs.size(); i != e; ++i)
ReadNonterminal(NTs[i]);
}
/// ReadInstructionPatterns - Read in all subclasses of Instruction, and process
/// those with a useful Pattern field.
///
void InstrSelectorEmitter::ReadInstructionPatterns() {
std::vector<Record*> Insts = Records.getAllDerivedDefinitions("Instruction");
for (unsigned i = 0, e = Insts.size(); i != e; ++i) {
Record *Inst = Insts[i];
if (DagInit *DI = dynamic_cast<DagInit*>(Inst->getValueInit("Pattern"))) {
Patterns[Inst] = new Pattern(Pattern::Instruction, DI, Inst, *this);
DEBUG(std::cerr << "Parsed " << *Patterns[Inst] << "\n");
}
}
}
/// ReadExpanderPatterns - Read in all expander patterns...
///
void InstrSelectorEmitter::ReadExpanderPatterns() {
std::vector<Record*> Expanders = Records.getAllDerivedDefinitions("Expander");
for (unsigned i = 0, e = Expanders.size(); i != e; ++i) {
Record *Expander = Expanders[i];
DagInit *DI = Expander->getValueAsDag("Pattern");
Patterns[Expander] = new Pattern(Pattern::Expander, DI, Expander, *this);
DEBUG(std::cerr << "Parsed " << *Patterns[Expander] << "\n");
}
}
// InstantiateNonterminals - Instantiate any unresolved nonterminals with
// information from the context that they are used in.
//
void InstrSelectorEmitter::InstantiateNonterminals() {
DEBUG(std::cerr << "Instantiating nonterminals:\n");
for (std::map<Record*, Pattern*>::iterator I = Patterns.begin(),
E = Patterns.end(); I != E; ++I)
if (I->second->isResolved())
I->second->InstantiateNonterminals();
}
/// InstantiateNonterminal - This method takes the nonterminal specified by
/// NT, which should not be completely resolved, clones it, applies ResultTy
/// to its root, then runs the type inference stuff on it. This should
/// produce a newly resolved nonterminal, which we make a record for and
/// return. To be extra fancy and efficient, this only makes one clone for
/// each type it is instantiated with.
Record *InstrSelectorEmitter::InstantiateNonterminal(Pattern *NT,
MVT::ValueType ResultTy) {
assert(!NT->isResolved() && "Nonterminal is already resolved!");
// Check to see if we have already instantiated this pair...
Record* &Slot = InstantiatedNTs[std::make_pair(NT, ResultTy)];
if (Slot) return Slot;
Record *New = new Record(NT->getRecord()->getName()+"_"+getName(ResultTy));
// Copy over the superclasses...
const std::vector<Record*> &SCs = NT->getRecord()->getSuperClasses();
for (unsigned i = 0, e = SCs.size(); i != e; ++i)
New->addSuperClass(SCs[i]);
DEBUG(std::cerr << " Nonterminal '" << NT->getRecord()->getName()
<< "' for type '" << getName(ResultTy) << "', producing '"
<< New->getName() << "'\n");
// Copy the pattern...
Pattern *NewPat = NT->clone(New);
// Apply the type to the root...
NewPat->getTree()->updateNodeType(ResultTy, New->getName());
// Infer types...
NewPat->InferAllTypes();
// Make sure everything is good to go now...
if (!NewPat->isResolved())
NewPat->error("Instantiating nonterminal did not resolve all types!");
// Add the pattern to the patterns map, add the record to the RecordKeeper,
// return the new record.
Patterns[New] = NewPat;
Records.addDef(New);
return Slot = New;
}
// CalculateComputableValues - Fill in the ComputableValues map through
// analysis of the patterns we are playing with.
void InstrSelectorEmitter::CalculateComputableValues() {
// Loop over all of the patterns, adding them to the ComputableValues map
for (std::map<Record*, Pattern*>::iterator I = Patterns.begin(),
E = Patterns.end(); I != E; ++I)
if (I->second->isResolved()) {
// We don't want to add patterns like R32 = R32. This is a hack working
// around a special case of a general problem, but for now we explicitly
// forbid these patterns. They can never match anyway.
Pattern *P = I->second;
if (!P->getResult() || !P->getTree()->isLeaf() ||
P->getResult() != P->getTree()->getValueRecord())
ComputableValues.addPattern(P);
}
}
#if 0
// MoveIdenticalPatterns - Given a tree pattern 'P', move all of the tree
// patterns which have the same top-level structure as P from the 'From' list to
// the 'To' list.
static void MoveIdenticalPatterns(TreePatternNode *P,
std::vector<std::pair<Pattern*, TreePatternNode*> > &From,
std::vector<std::pair<Pattern*, TreePatternNode*> > &To) {
assert(!P->isLeaf() && "All leaves are identical!");
const std::vector<TreePatternNode*> &PChildren = P->getChildren();
for (unsigned i = 0; i != From.size(); ++i) {
TreePatternNode *N = From[i].second;
assert(P->getOperator() == N->getOperator() &&"Differing operators?");
assert(PChildren.size() == N->getChildren().size() &&
"Nodes with different arity??");
bool isDifferent = false;
for (unsigned c = 0, e = PChildren.size(); c != e; ++c) {
TreePatternNode *PC = PChildren[c];
TreePatternNode *NC = N->getChild(c);
if (PC->isLeaf() != NC->isLeaf()) {
isDifferent = true;
break;
}
if (!PC->isLeaf()) {
if (PC->getOperator() != NC->getOperator()) {
isDifferent = true;
break;
}
} else { // It's a leaf!
if (PC->getValueRecord() != NC->getValueRecord()) {
isDifferent = true;
break;
}
}
}
// If it's the same as the reference one, move it over now...
if (!isDifferent) {
To.push_back(std::make_pair(From[i].first, N));
From.erase(From.begin()+i);
--i; // Don't skip an entry...
}
}
}
#endif
static std::string getNodeName(Record *R) {
RecordVal *RV = R->getValue("EnumName");
if (RV)
if (Init *I = RV->getValue())
if (StringInit *SI = dynamic_cast<StringInit*>(I))
return SI->getValue();
return R->getName();
}
static void EmitPatternPredicates(TreePatternNode *Tree,
const std::string &VarName, std::ostream &OS){
OS << " && " << VarName << "->getNodeType() == ISD::"
<< getNodeName(Tree->getOperator());
for (unsigned c = 0, e = Tree->getNumChildren(); c != e; ++c)
if (!Tree->getChild(c)->isLeaf())
EmitPatternPredicates(Tree->getChild(c),
VarName + "->getUse(" + utostr(c)+")", OS);
}
static void EmitPatternCosts(TreePatternNode *Tree, const std::string &VarName,
std::ostream &OS) {
for (unsigned c = 0, e = Tree->getNumChildren(); c != e; ++c)
if (Tree->getChild(c)->isLeaf()) {
OS << " + Match_"
<< Pattern::getSlotName(Tree->getChild(c)->getValueRecord()) << "("
<< VarName << "->getUse(" << c << "))";
} else {
EmitPatternCosts(Tree->getChild(c),
VarName + "->getUse(" + utostr(c) + ")", OS);
}
}
// EmitMatchCosters - Given a list of patterns, which all have the same root
// pattern operator, emit an efficient decision tree to decide which one to
// pick. This is structured this way to avoid reevaluations of non-obvious
// subexpressions.
void InstrSelectorEmitter::EmitMatchCosters(std::ostream &OS,
const std::vector<std::pair<Pattern*, TreePatternNode*> > &Patterns,
const std::string &VarPrefix,
unsigned IndentAmt) {
assert(!Patterns.empty() && "No patterns to emit matchers for!");
std::string Indent(IndentAmt, ' ');
// Load all of the operands of the root node into scalars for fast access
const NodeType &ONT = getNodeType(Patterns[0].second->getOperator());
for (unsigned i = 0, e = ONT.ArgTypes.size(); i != e; ++i)
OS << Indent << "SelectionDAGNode *" << VarPrefix << "_Op" << i
<< " = N->getUse(" << i << ");\n";
// Compute the costs of computing the various nonterminals/registers, which
// are directly used at this level.
OS << "\n" << Indent << "// Operand matching costs...\n";
std::set<std::string> ComputedValues; // Avoid duplicate computations...
for (unsigned i = 0, e = Patterns.size(); i != e; ++i) {
TreePatternNode *NParent = Patterns[i].second;
for (unsigned c = 0, e = NParent->getNumChildren(); c != e; ++c) {
TreePatternNode *N = NParent->getChild(c);
if (N->isLeaf()) {
Record *VR = N->getValueRecord();
const std::string &LeafName = VR->getName();
std::string OpName = VarPrefix + "_Op" + utostr(c);
std::string ValName = OpName + "_" + LeafName + "_Cost";
if (!ComputedValues.count(ValName)) {
OS << Indent << "unsigned " << ValName << " = Match_"
<< Pattern::getSlotName(VR) << "(" << OpName << ");\n";
ComputedValues.insert(ValName);
}
}
}
}
OS << "\n";
std::string LocCostName = VarPrefix + "_Cost";
OS << Indent << "unsigned " << LocCostName << "Min = ~0U >> 1;\n"
<< Indent << "unsigned " << VarPrefix << "_PatternMin = NoMatchPattern;\n";
#if 0
// Separate out all of the patterns into groups based on what their top-level
// signature looks like...
std::vector<std::pair<Pattern*, TreePatternNode*> > PatternsLeft(Patterns);
while (!PatternsLeft.empty()) {
// Process all of the patterns that have the same signature as the last
// element...
std::vector<std::pair<Pattern*, TreePatternNode*> > Group;
MoveIdenticalPatterns(PatternsLeft.back().second, PatternsLeft, Group);
assert(!Group.empty() && "Didn't at least pick the source pattern?");
#if 0
OS << "PROCESSING GROUP:\n";
for (unsigned i = 0, e = Group.size(); i != e; ++i)
OS << " " << *Group[i].first << "\n";
OS << "\n\n";
#endif
OS << Indent << "{ // ";
if (Group.size() != 1) {
OS << Group.size() << " size group...\n";
OS << Indent << " unsigned " << VarPrefix << "_Pattern = NoMatch;\n";
} else {
OS << *Group[0].first << "\n";
OS << Indent << " unsigned " << VarPrefix << "_Pattern = "
<< Group[0].first->getRecord()->getName() << "_Pattern;\n";
}
OS << Indent << " unsigned " << LocCostName << " = ";
if (Group.size() == 1)
OS << "1;\n"; // Add inst cost if at individual rec
else
OS << "0;\n";
// Loop over all of the operands, adding in their costs...
TreePatternNode *N = Group[0].second;
const std::vector<TreePatternNode*> &Children = N->getChildren();
// If necessary, emit conditionals to check for the appropriate tree
// structure here...
for (unsigned i = 0, e = Children.size(); i != e; ++i) {
TreePatternNode *C = Children[i];
if (C->isLeaf()) {
// We already calculated the cost for this leaf, add it in now...
OS << Indent << " " << LocCostName << " += "
<< VarPrefix << "_Op" << utostr(i) << "_"
<< C->getValueRecord()->getName() << "_Cost;\n";
} else {
// If it's not a leaf, we have to check to make sure that the current
// node has the appropriate structure, then recurse into it...
OS << Indent << " if (" << VarPrefix << "_Op" << i
<< "->getNodeType() == ISD::" << getNodeName(C->getOperator())
<< ") {\n";
std::vector<std::pair<Pattern*, TreePatternNode*> > SubPatterns;
for (unsigned n = 0, e = Group.size(); n != e; ++n)
SubPatterns.push_back(std::make_pair(Group[n].first,
Group[n].second->getChild(i)));
EmitMatchCosters(OS, SubPatterns, VarPrefix+"_Op"+utostr(i),
IndentAmt + 4);
OS << Indent << " }\n";
}
}
// If the cost for this match is less than the minimum computed cost so far,
// update the minimum cost and selected pattern.
OS << Indent << " if (" << LocCostName << " < " << LocCostName << "Min) { "
<< LocCostName << "Min = " << LocCostName << "; " << VarPrefix
<< "_PatternMin = " << VarPrefix << "_Pattern; }\n";
OS << Indent << "}\n";
}
#endif
for (unsigned i = 0, e = Patterns.size(); i != e; ++i) {
Pattern *P = Patterns[i].first;
TreePatternNode *PTree = P->getTree();
unsigned PatternCost = 1;
// Check to see if there are any non-leaf elements in the pattern. If so,
// we need to emit a predicate for this match.
bool AnyNonLeaf = false;
for (unsigned c = 0, e = PTree->getNumChildren(); c != e; ++c)
if (!PTree->getChild(c)->isLeaf()) {
AnyNonLeaf = true;
break;
}
if (!AnyNonLeaf) { // No predicate necessary, just output a scope...
OS << " {// " << *P << "\n";
} else {
// We need to emit a predicate to make sure the tree pattern matches, do
// so now...
OS << " if (1";
for (unsigned c = 0, e = PTree->getNumChildren(); c != e; ++c)
if (!PTree->getChild(c)->isLeaf())
EmitPatternPredicates(PTree->getChild(c),
VarPrefix + "_Op" + utostr(c), OS);
OS << ") {\n // " << *P << "\n";
}
OS << " unsigned PatCost = " << PatternCost;
for (unsigned c = 0, e = PTree->getNumChildren(); c != e; ++c)
if (PTree->getChild(c)->isLeaf()) {
OS << " + " << VarPrefix << "_Op" << c << "_"
<< PTree->getChild(c)->getValueRecord()->getName() << "_Cost";
} else {
EmitPatternCosts(PTree->getChild(c), VarPrefix + "_Op" + utostr(c), OS);
}
OS << ";\n";
OS << " if (PatCost < MinCost) { MinCost = PatCost; Pattern = "
<< P->getRecord()->getName() << "_Pattern; }\n"
<< " }\n";
}
}
static void ReduceAllOperands(TreePatternNode *N, const std::string &Name,
std::vector<std::pair<TreePatternNode*, std::string> > &Operands,
std::ostream &OS) {
if (N->isLeaf()) {
// If this is a leaf, register or nonterminal reference...
std::string SlotName = Pattern::getSlotName(N->getValueRecord());
OS << " ReducedValue_" << SlotName << " *" << Name << "Val = Reduce_"
<< SlotName << "(" << Name << ", MBB);\n";
Operands.push_back(std::make_pair(N, Name+"Val"));
} else if (N->getNumChildren() == 0) {
// This is a reference to a leaf tree node, like an immediate or frame
// index.
if (N->getType() != MVT::isVoid) {
std::string SlotName =
getNodeName(N->getOperator()) + "_" + getName(N->getType());
OS << " ReducedValue_" << SlotName << " *" << Name << "Val = "
<< Name << "->getValue<ReducedValue_" << SlotName << ">(ISD::"
<< SlotName << "_Slot);\n";
Operands.push_back(std::make_pair(N, Name+"Val"));
}
} else {
// Otherwise this is an interior node...
for (unsigned i = 0, e = N->getNumChildren(); i != e; ++i) {
std::string ChildName = Name + "_Op" + utostr(i);
OS << " SelectionDAGNode *" << ChildName << " = " << Name
<< "->getUse(" << i << ");\n";
ReduceAllOperands(N->getChild(i), ChildName, Operands, OS);
}
}
}
/// PrintExpanderOperand - Print out Arg as part of the instruction emission
/// process for the expander pattern P. This argument may be referencing some
/// values defined in P, or may just be physical register references or
/// something like that. If PrintArg is true, we are printing out arguments to
/// the BuildMI call. If it is false, we are printing the result register
/// name.
void InstrSelectorEmitter::PrintExpanderOperand(Init *Arg,
const std::string &NameVar,
TreePatternNode *ArgDeclNode,
Pattern *P, bool PrintArg,
std::ostream &OS) {
if (DefInit *DI = dynamic_cast<DefInit*>(Arg)) {
Record *Arg = DI->getDef();
if (!ArgDeclNode->isLeaf() && ArgDeclNode->getNumChildren() != 0)
P->error("Expected leaf node as argument!");
Record *ArgDecl = ArgDeclNode->isLeaf() ? ArgDeclNode->getValueRecord() :
ArgDeclNode->getOperator();
if (Arg->isSubClassOf("Register")) {
// This is a physical register reference... make sure that the instruction
// requested a register!
if (!ArgDecl->isSubClassOf("RegisterClass"))
P->error("Argument mismatch for instruction pattern!");
// FIXME: This should check to see if the register is in the specified
// register class!
if (PrintArg) OS << ".addReg(";
OS << getQualifiedName(Arg);
if (PrintArg) OS << ")";
return;
} else if (Arg->isSubClassOf("RegisterClass")) {
// If this is a symbolic register class reference, we must be using a
// named value.
if (NameVar.empty()) P->error("Did not specify WHICH register to pass!");
if (Arg != ArgDecl) P->error("Instruction pattern mismatch!");
if (PrintArg) OS << ".addReg(";
OS << NameVar;
if (PrintArg) OS << ")";
return;
} else if (Arg->getName() == "frameidx") {
if (!PrintArg) P->error("Cannot define a new frameidx value!");
OS << ".addFrameIndex(" << NameVar << ")";
return;
} else if (Arg->getName() == "basicblock") {
if (!PrintArg) P->error("Cannot define a new basicblock value!");
OS << ".addMBB(" << NameVar << ")";
return;
}
P->error("Unknown operand type '" + Arg->getName() + "' to expander!");
} else if (IntInit *II = dynamic_cast<IntInit*>(Arg)) {
if (!NameVar.empty())
P->error("Illegal to specify a name for a constant initializer arg!");
// Hack this check to allow R32 values with 0 as the initializer for memory
// references... FIXME!
if (ArgDeclNode->isLeaf() && II->getValue() == 0 &&
ArgDeclNode->getValueRecord()->getName() == "R32") {
OS << ".addReg(0)";
} else {
if (ArgDeclNode->isLeaf() || ArgDeclNode->getOperator()->getName()!="imm")
P->error("Illegal immediate int value '" + itostr(II->getValue()) +
"' operand!");
OS << ".addZImm(" << II->getValue() << ")";
}
return;
}
P->error("Unknown operand type to expander!");
}
static std::string getArgName(Pattern *P, const std::string &ArgName,
const std::vector<std::pair<TreePatternNode*, std::string> > &Operands) {
assert(P->getNumArgs() == Operands.size() &&"Argument computation mismatch!");
if (ArgName.empty()) return "";
for (unsigned i = 0, e = P->getNumArgs(); i != e; ++i)
if (P->getArgName(i) == ArgName)
return Operands[i].second + "->Val";
if (ArgName == P->getResultName())
return "NewReg";
P->error("Pattern does not define a value named $" + ArgName + "!");
return "";
}
void InstrSelectorEmitter::run(std::ostream &OS) {
// Type-check all of the node types to ensure we "understand" them.
ReadNodeTypes();
// Read in all of the nonterminals, instructions, and expanders...
ReadNonterminals();
ReadInstructionPatterns();
ReadExpanderPatterns();
// Instantiate any unresolved nonterminals with information from the context
// that they are used in.
InstantiateNonterminals();
// Clear InstantiatedNTs, we don't need it anymore...
InstantiatedNTs.clear();
DEBUG(std::cerr << "Patterns acquired:\n");
for (std::map<Record*, Pattern*>::iterator I = Patterns.begin(),
E = Patterns.end(); I != E; ++I)
if (I->second->isResolved())
DEBUG(std::cerr << " " << *I->second << "\n");
CalculateComputableValues();
OS << "#include \"llvm/CodeGen/MachineInstrBuilder.h\"\n";
EmitSourceFileHeader("Instruction Selector for the " + Target.getName() +
" target", OS);
OS << "namespace llvm {\n\n";
// Output the slot number enums...
OS << "\nenum { // Slot numbers...\n"
<< " LastBuiltinSlot = ISD::NumBuiltinSlots-1, // Start numbering here\n";
for (PatternOrganizer::iterator I = ComputableValues.begin(),
E = ComputableValues.end(); I != E; ++I)
OS << " " << I->first << "_Slot,\n";
OS << " NumSlots\n};\n\n// Reduction value typedefs...\n";
// Output the reduction value typedefs...
for (PatternOrganizer::iterator I = ComputableValues.begin(),
E = ComputableValues.end(); I != E; ++I) {
OS << "typedef ReducedValue<unsigned, " << I->first
<< "_Slot> ReducedValue_" << I->first << ";\n";
}
// Output the pattern enums...
OS << "\n\n"
<< "enum { // Patterns...\n"
<< " NotComputed = 0,\n"
<< " NoMatchPattern, \n";
for (PatternOrganizer::iterator I = ComputableValues.begin(),
E = ComputableValues.end(); I != E; ++I) {
OS << " // " << I->first << " patterns...\n";
for (PatternOrganizer::NodesForSlot::iterator J = I->second.begin(),
E = I->second.end(); J != E; ++J)
for (unsigned i = 0, e = J->second.size(); i != e; ++i)
OS << " " << J->second[i]->getRecord()->getName() << "_Pattern,\n";
}
OS << "};\n\n";
//===--------------------------------------------------------------------===//
// Emit the class definition...
//
OS << "namespace {\n"
<< " class " << Target.getName() << "ISel {\n"
<< " SelectionDAG &DAG;\n"
<< " public:\n"
<< " " << Target.getName () << "ISel(SelectionDAG &D) : DAG(D) {}\n"
<< " void generateCode();\n"
<< " private:\n"
<< " unsigned makeAnotherReg(const TargetRegisterClass *RC) {\n"
<< " return DAG.getMachineFunction().getSSARegMap()->createVirt"
"ualRegister(RC);\n"
<< " }\n\n"
<< " // DAG matching methods for classes... all of these methods"
" return the cost\n"
<< " // of producing a value of the specified class and type, which"
" also gets\n"
<< " // added to the DAG node.\n";
// Output all of the matching prototypes for slots...
for (PatternOrganizer::iterator I = ComputableValues.begin(),
E = ComputableValues.end(); I != E; ++I)
OS << " unsigned Match_" << I->first << "(SelectionDAGNode *N);\n";
OS << "\n // DAG matching methods for DAG nodes...\n";
// Output all of the matching prototypes for slot/node pairs
for (PatternOrganizer::iterator I = ComputableValues.begin(),
E = ComputableValues.end(); I != E; ++I)
for (PatternOrganizer::NodesForSlot::iterator J = I->second.begin(),
E = I->second.end(); J != E; ++J)
OS << " unsigned Match_" << I->first << "_" << getNodeName(J->first)
<< "(SelectionDAGNode *N);\n";
// Output all of the dag reduction methods prototypes...
OS << "\n // DAG reduction methods...\n";
for (PatternOrganizer::iterator I = ComputableValues.begin(),
E = ComputableValues.end(); I != E; ++I)
OS << " ReducedValue_" << I->first << " *Reduce_" << I->first
<< "(SelectionDAGNode *N,\n" << std::string(27+2*I->first.size(), ' ')
<< "MachineBasicBlock *MBB);\n";
OS << " };\n}\n\n";
// Emit the generateCode entry-point...
OS << "void " << Target.getName () << "ISel::generateCode() {\n"
<< " SelectionDAGNode *Root = DAG.getRoot();\n"
<< " assert(Root->getValueType() == MVT::isVoid && "
"\"Root of DAG produces value??\");\n\n"
<< " std::cerr << \"\\n\";\n"
<< " unsigned Cost = Match_Void_void(Root);\n"
<< " if (Cost >= ~0U >> 1) {\n"
<< " std::cerr << \"Match failed!\\n\";\n"
<< " Root->dump();\n"
<< " abort();\n"
<< " }\n\n"
<< " std::cerr << \"Total DAG Cost: \" << Cost << \"\\n\\n\";\n\n"
<< " Reduce_Void_void(Root, 0);\n"
<< "}\n\n"
<< "//===" << std::string(70, '-') << "===//\n"
<< "// Matching methods...\n"
<< "//\n\n";
//===--------------------------------------------------------------------===//
// Emit all of the matcher methods...
//
for (PatternOrganizer::iterator I = ComputableValues.begin(),
E = ComputableValues.end(); I != E; ++I) {
const std::string &SlotName = I->first;
OS << "unsigned " << Target.getName() << "ISel::Match_" << SlotName
<< "(SelectionDAGNode *N) {\n"
<< " assert(N->getValueType() == MVT::"
<< getEnumName((*I->second.begin()).second[0]->getTree()->getType())
<< ");\n" << " // If we already have a cost available for " << SlotName
<< " use it!\n"
<< " if (N->getPatternFor(" << SlotName << "_Slot))\n"
<< " return N->getCostFor(" << SlotName << "_Slot);\n\n"
<< " unsigned Cost;\n"
<< " switch (N->getNodeType()) {\n"
<< " default: Cost = ~0U >> 1; // Match failed\n"
<< " N->setPatternCostFor(" << SlotName << "_Slot, NoMatchPattern, Cost, NumSlots);\n"
<< " break;\n";
for (PatternOrganizer::NodesForSlot::iterator J = I->second.begin(),
E = I->second.end(); J != E; ++J)
if (!J->first->isSubClassOf("Nonterminal"))
OS << " case ISD::" << getNodeName(J->first) << ":\tCost = Match_"
<< SlotName << "_" << getNodeName(J->first) << "(N); break;\n";
OS << " }\n"; // End of the switch statement
// Emit any patterns which have a nonterminal leaf as the RHS. These may
// match multiple root nodes, so they cannot be handled with the switch...
for (PatternOrganizer::NodesForSlot::iterator J = I->second.begin(),
E = I->second.end(); J != E; ++J)
if (J->first->isSubClassOf("Nonterminal")) {
OS << " unsigned " << J->first->getName() << "_Cost = Match_"
<< getNodeName(J->first) << "(N);\n"
<< " if (" << getNodeName(J->first) << "_Cost < Cost) Cost = "
<< getNodeName(J->first) << "_Cost;\n";
}
OS << " return Cost;\n}\n\n";
for (PatternOrganizer::NodesForSlot::iterator J = I->second.begin(),
E = I->second.end(); J != E; ++J) {
Record *Operator = J->first;
bool isNonterm = Operator->isSubClassOf("Nonterminal");
if (!isNonterm) {
OS << "unsigned " << Target.getName() << "ISel::Match_";
if (!isNonterm) OS << SlotName << "_";
OS << getNodeName(Operator) << "(SelectionDAGNode *N) {\n"
<< " unsigned Pattern = NoMatchPattern;\n"
<< " unsigned MinCost = ~0U >> 1;\n";
std::vector<std::pair<Pattern*, TreePatternNode*> > Patterns;
for (unsigned i = 0, e = J->second.size(); i != e; ++i)
Patterns.push_back(std::make_pair(J->second[i],
J->second[i]->getTree()));
EmitMatchCosters(OS, Patterns, "N", 2);
OS << "\n N->setPatternCostFor(" << SlotName
<< "_Slot, Pattern, MinCost, NumSlots);\n"
<< " return MinCost;\n"
<< "}\n";
}
}
}
//===--------------------------------------------------------------------===//
// Emit all of the reducer methods...
//
OS << "\n\n//===" << std::string(70, '-') << "===//\n"
<< "// Reducer methods...\n"
<< "//\n";
for (PatternOrganizer::iterator I = ComputableValues.begin(),
E = ComputableValues.end(); I != E; ++I) {
const std::string &SlotName = I->first;
OS << "ReducedValue_" << SlotName << " *" << Target.getName()
<< "ISel::Reduce_" << SlotName
<< "(SelectionDAGNode *N, MachineBasicBlock *MBB) {\n"
<< " ReducedValue_" << SlotName << " *Val = N->hasValue<ReducedValue_"
<< SlotName << ">(" << SlotName << "_Slot);\n"
<< " if (Val) return Val;\n"
<< " if (N->getBB()) MBB = N->getBB();\n\n"
<< " switch (N->getPatternFor(" << SlotName << "_Slot)) {\n";
// Loop over all of the patterns that can produce a value for this slot...
PatternOrganizer::NodesForSlot &NodesForSlot = I->second;
for (PatternOrganizer::NodesForSlot::iterator J = NodesForSlot.begin(),
E = NodesForSlot.end(); J != E; ++J)
for (unsigned i = 0, e = J->second.size(); i != e; ++i) {
Pattern *P = J->second[i];
OS << " case " << P->getRecord()->getName() << "_Pattern: {\n"
<< " // " << *P << "\n";
// Loop over the operands, reducing them...
std::vector<std::pair<TreePatternNode*, std::string> > Operands;
ReduceAllOperands(P->getTree(), "N", Operands, OS);
// Now that we have reduced all of our operands, and have the values
// that reduction produces, perform the reduction action for this
// pattern.
std::string Result;
// If the pattern produces a register result, generate a new register
// now.
if (Record *R = P->getResult()) {
assert(R->isSubClassOf("RegisterClass") &&
"Only handle register class results so far!");
OS << " unsigned NewReg = makeAnotherReg(" << Target.getName()
<< "::" << R->getName() << "RegisterClass);\n";
Result = "NewReg";
DEBUG(OS << " std::cerr << \"%reg\" << NewReg << \" =\t\";\n");
} else {
DEBUG(OS << " std::cerr << \"\t\t\";\n");
Result = "0";
}
// Print out the pattern that matched...
DEBUG(OS << " std::cerr << \" " << P->getRecord()->getName() <<'"');
DEBUG(for (unsigned i = 0, e = Operands.size(); i != e; ++i)
if (Operands[i].first->isLeaf()) {
Record *RV = Operands[i].first->getValueRecord();
assert(RV->isSubClassOf("RegisterClass") &&
"Only handles registers here so far!");
OS << " << \" %reg\" << " << Operands[i].second
<< "->Val";
} else {
OS << " << ' ' << " << Operands[i].second
<< "->Val";
});
DEBUG(OS << " << \"\\n\";\n");
// Generate the reduction code appropriate to the particular type of
// pattern that this is...
switch (P->getPatternType()) {
case Pattern::Instruction:
// Instruction patterns just emit a single MachineInstr, using BuildMI
OS << " BuildMI(MBB, " << Target.getName() << "::"
<< P->getRecord()->getName() << ", " << Operands.size();
if (P->getResult()) OS << ", NewReg";
OS << ")";
for (unsigned i = 0, e = Operands.size(); i != e; ++i) {
TreePatternNode *Op = Operands[i].first;
if (Op->isLeaf()) {
Record *RV = Op->getValueRecord();
assert(RV->isSubClassOf("RegisterClass") &&
"Only handles registers here so far!");
OS << ".addReg(" << Operands[i].second << "->Val)";
} else if (Op->getOperator()->getName() == "imm") {
OS << ".addZImm(" << Operands[i].second << "->Val)";
} else if (Op->getOperator()->getName() == "basicblock") {
OS << ".addMBB(" << Operands[i].second << "->Val)";
} else {
assert(0 && "Unknown value type!");
}
}
OS << ";\n";
break;
case Pattern::Expander: {
// Expander patterns emit one machine instr for each instruction in
// the list of instructions expanded to.
ListInit *Insts = P->getRecord()->getValueAsListInit("Result");
for (unsigned IN = 0, e = Insts->getSize(); IN != e; ++IN) {
DagInit *DIInst = dynamic_cast<DagInit*>(Insts->getElement(IN));
if (!DIInst) P->error("Result list must contain instructions!");
Record *InstRec = DIInst->getNodeType();
Pattern *InstPat = getPattern(InstRec);
if (!InstPat || InstPat->getPatternType() != Pattern::Instruction)
P->error("Instruction list must contain Instruction patterns!");
bool hasResult = InstPat->getResult() != 0;
if (InstPat->getNumArgs() != DIInst->getNumArgs()-hasResult) {
P->error("Incorrect number of arguments specified for inst '" +
InstPat->getRecord()->getName() + "' in result list!");
}
// Start emission of the instruction...
OS << " BuildMI(MBB, " << Target.getName() << "::"
<< InstRec->getName() << ", "
<< DIInst->getNumArgs()-hasResult;
// Emit register result if necessary..
if (hasResult) {
std::string ArgNameVal =
getArgName(P, DIInst->getArgName(0), Operands);
PrintExpanderOperand(DIInst->getArg(0), ArgNameVal,
InstPat->getResultNode(), P, false,
OS << ", ");
}
OS << ")";
for (unsigned i = hasResult, e = DIInst->getNumArgs(); i != e; ++i){
std::string ArgNameVal =
getArgName(P, DIInst->getArgName(i), Operands);
PrintExpanderOperand(DIInst->getArg(i), ArgNameVal,
InstPat->getArg(i-hasResult), P, true, OS);
}
OS << ";\n";
}
break;
}
default:
assert(0 && "Reduction of this type of pattern not implemented!");
}
OS << " Val = new ReducedValue_" << SlotName << "(" << Result<<");\n"
<< " break;\n"
<< " }\n";
}
OS << " default: assert(0 && \"Unknown " << SlotName << " pattern!\");\n"
<< " }\n\n N->addValue(Val); // Do not ever recalculate this\n"
<< " return Val;\n}\n\n";
}
OS << "} // End llvm namespace \n";
}