llvm/lib/CodeGen/SelectionDAG/DAGBuilder.cpp
2004-10-08 19:43:31 +00:00

279 lines
9.9 KiB
C++

//===-- DAGBuilder.cpp - Turn an LLVM BasicBlock into a DAG for selection -===//
//
// 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 file turns an LLVM BasicBlock into a target-independent SelectionDAG in
// preparation for target-specific optimizations and instruction selection.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/Constants.h"
#include "llvm/Function.h"
#include "llvm/Instructions.h"
#include "llvm/Type.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Support/InstVisitor.h"
#include <iostream>
using namespace llvm;
namespace llvm {
struct SelectionDAGBuilder : public InstVisitor<SelectionDAGBuilder> {
// DAG - the current dag we are building.
SelectionDAG &DAG;
// SDTB - The target-specific builder interface, which indicates how to expand
// extremely target-specific aspects of the representation, such as function
// calls and arguments.
SelectionDAGTargetBuilder &SDTB;
// BB - The current machine basic block we are working on.
MachineBasicBlock *BB;
// CurRoot - The root built for the current basic block.
SelectionDAGNode *CurRoot;
SelectionDAGBuilder(SelectionDAG &dag, SelectionDAGTargetBuilder &sdtb)
: DAG(dag), SDTB(sdtb), BB(0), CurRoot(0) {}
void visitBB(BasicBlock &bb);
// Visitation methods for instructions: Create the appropriate DAG nodes for
// the instruction.
void visitAdd(BinaryOperator &BO);
void visitSub(BinaryOperator &BO);
void visitMul(BinaryOperator &BO);
void visitAnd(BinaryOperator &BO);
void visitOr (BinaryOperator &BO);
void visitXor(BinaryOperator &BO);
void visitSetEQ(BinaryOperator &BO);
void visitLoad(LoadInst &LI);
void visitCall(CallInst &CI);
void visitBr(BranchInst &BI);
void visitRet(ReturnInst &RI);
void visitInstruction(Instruction &I) {
std::cerr << "DAGBuilder: Cannot instruction select: " << I;
abort();
}
private:
SelectionDAGNode *getNodeFor(Value *V);
SelectionDAGNode *getNodeFor(Value &V) { return getNodeFor(&V); }
SelectionDAGNode *addSeqNode(SelectionDAGNode *N);
};
} // end llvm namespace
/// addSeqNode - The same as addNode, but the node is also included in the
/// sequence nodes for this block. This method should be called for any
/// instructions which have a specified sequence they must be evaluated in.
///
SelectionDAGNode *SelectionDAGBuilder::addSeqNode(SelectionDAGNode *N) {
DAG.addNode(N); // First, add the node to the selection DAG
if (!CurRoot)
CurRoot = N;
else {
// Create and add a new chain node for the existing root and this node...
CurRoot = DAG.addNode(new SelectionDAGNode(ISD::ChainNode, MVT::isVoid,
BB, CurRoot, N));
}
return N;
}
/// getNodeFor - This method returns the SelectionDAGNode for the specified LLVM
/// value, creating a node as necessary.
///
SelectionDAGNode *SelectionDAGBuilder::getNodeFor(Value *V) {
// If we already have the entry, return it.
SelectionDAGNode*& Entry = DAG.ValueMap[V];
if (Entry) return Entry;
// Otherwise, we need to create a node to return now... start by figuring out
// which type the node will be...
MVT::ValueType ValueType = DAG.getValueType(V->getType());
if (Instruction *I = dyn_cast<Instruction>(V))
// Instructions will be filled in later. For now, just create and return a
// dummy node.
return Entry = new SelectionDAGNode(ISD::ProtoNode, ValueType);
if (Constant *C = dyn_cast<Constant>(V)) {
if (ConstantBool *CB = dyn_cast<ConstantBool>(C)) {
Entry = new SelectionDAGNode(ISD::Constant, ValueType);
Entry->addValue(new ReducedValue_Constant_i1(CB->getValue()));
} else if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) {
Entry = new SelectionDAGNode(ISD::Constant, ValueType);
switch (ValueType) {
case MVT::i8:
Entry->addValue(new ReducedValue_Constant_i8(CI->getRawValue()));
break;
case MVT::i16:
Entry->addValue(new ReducedValue_Constant_i16(CI->getRawValue()));
break;
case MVT::i32:
Entry->addValue(new ReducedValue_Constant_i32(CI->getRawValue()));
break;
case MVT::i64:
Entry->addValue(new ReducedValue_Constant_i64(CI->getRawValue()));
break;
default:
assert(0 && "Invalid ValueType for an integer constant!");
}
} else if (ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
Entry = new SelectionDAGNode(ISD::Constant, ValueType);
if (ValueType == MVT::f32)
Entry->addValue(new ReducedValue_Constant_f32(CFP->getValue()));
else
Entry->addValue(new ReducedValue_Constant_f64(CFP->getValue()));
}
if (Entry) return Entry;
} else if (BasicBlock *BB = dyn_cast<BasicBlock>(V)) {
Entry = new SelectionDAGNode(ISD::BasicBlock, ValueType);
Entry->addValue(new ReducedValue_BasicBlock_i32(DAG.BlockMap[BB]));
return Entry;
}
std::cerr << "Unhandled LLVM value in DAG Builder!: " << *V << "\n";
abort();
return 0;
}
// visitBB - This method is used to visit a basic block in the program. It
// manages the CurRoot instance variable so that all of the visit(Instruction)
// methods can be written to assume that there is only one basic block being
// constructed.
//
void SelectionDAGBuilder::visitBB(BasicBlock &bb) {
BB = DAG.BlockMap[&bb]; // Update BB instance var
// Save the current global DAG...
SelectionDAGNode *OldRoot = CurRoot;
CurRoot = 0;
visit(bb.begin(), bb.end()); // Visit all of the instructions...
if (OldRoot) {
if (!CurRoot)
CurRoot = OldRoot; // This block had no root of its own..
else {
// The previous basic block AND this basic block had roots, insert a
// block chain node now...
CurRoot = DAG.addNode(new SelectionDAGNode(ISD::BlockChainNode,
MVT::isVoid,
BB, OldRoot, CurRoot));
}
}
}
//===----------------------------------------------------------------------===//
// ...Visitation Methods...
//===----------------------------------------------------------------------===//
void SelectionDAGBuilder::visitAdd(BinaryOperator &BO) {
getNodeFor(BO)->setNode(ISD::Plus, BB, getNodeFor(BO.getOperand(0)),
getNodeFor(BO.getOperand(1)));
}
void SelectionDAGBuilder::visitSub(BinaryOperator &BO) {
getNodeFor(BO)->setNode(ISD::Minus, BB, getNodeFor(BO.getOperand(0)),
getNodeFor(BO.getOperand(1)));
}
void SelectionDAGBuilder::visitMul(BinaryOperator &BO) {
getNodeFor(BO)->setNode(ISD::Times, BB, getNodeFor(BO.getOperand(0)),
getNodeFor(BO.getOperand(1)));
}
void SelectionDAGBuilder::visitAnd(BinaryOperator &BO) {
getNodeFor(BO)->setNode(ISD::And, BB, getNodeFor(BO.getOperand(0)),
getNodeFor(BO.getOperand(1)));
}
void SelectionDAGBuilder::visitOr(BinaryOperator &BO) {
getNodeFor(BO)->setNode(ISD::Or, BB, getNodeFor(BO.getOperand(0)),
getNodeFor(BO.getOperand(1)));
}
void SelectionDAGBuilder::visitXor(BinaryOperator &BO) {
getNodeFor(BO)->setNode(ISD::Xor, BB, getNodeFor(BO.getOperand(0)),
getNodeFor(BO.getOperand(1)));
}
void SelectionDAGBuilder::visitSetEQ(BinaryOperator &BO) {
getNodeFor(BO)->setNode(ISD::SetEQ, BB, getNodeFor(BO.getOperand(0)),
getNodeFor(BO.getOperand(1)));
}
void SelectionDAGBuilder::visitRet(ReturnInst &RI) {
if (RI.getNumOperands()) { // Value return
addSeqNode(new SelectionDAGNode(ISD::Ret, MVT::isVoid, BB,
getNodeFor(RI.getOperand(0))));
} else { // Void return
addSeqNode(new SelectionDAGNode(ISD::RetVoid, MVT::isVoid, BB));
}
}
void SelectionDAGBuilder::visitBr(BranchInst &BI) {
if (BI.isUnconditional())
addSeqNode(new SelectionDAGNode(ISD::Br, MVT::isVoid, BB,
getNodeFor(BI.getOperand(0))));
else
addSeqNode(new SelectionDAGNode(ISD::BrCond, MVT::isVoid, BB,
getNodeFor(BI.getCondition()),
getNodeFor(BI.getSuccessor(0)),
getNodeFor(BI.getSuccessor(1))));
}
void SelectionDAGBuilder::visitLoad(LoadInst &LI) {
// FIXME: this won't prevent reordering of loads!
getNodeFor(LI)->setNode(ISD::Load, BB, getNodeFor(LI.getOperand(0)));
}
void SelectionDAGBuilder::visitCall(CallInst &CI) {
SDTB.expandCall(DAG, CI);
}
// SelectionDAG constructor - Just use the SelectionDAGBuilder to do all of the
// dirty work...
SelectionDAG::SelectionDAG(MachineFunction &f, const TargetMachine &tm,
SelectionDAGTargetBuilder &SDTB)
: F(f), TM(tm) {
switch (TM.getTargetData().getPointerSize()) {
default: assert(0 && "Unknown pointer size!"); abort();
case 1: PointerType = MVT::i8; break;
case 2: PointerType = MVT::i16; break;
case 3: PointerType = MVT::i32; break;
case 4: PointerType = MVT::i64; break;
}
// Create all of the machine basic blocks for the function... building the
// BlockMap. This map is used for PHI node conversion.
const Function &Fn = *F.getFunction();
for (Function::const_iterator I = Fn.begin(), E = Fn.end(); I != E; ++I)
F.getBasicBlockList().push_back(BlockMap[I] = new MachineBasicBlock(I));
SDTB.expandArguments(*this);
SelectionDAGBuilder SDB(*this, SDTB);
for (Function::const_iterator I = Fn.begin(), E = Fn.end(); I != E; ++I)
SDB.visitBB(const_cast<BasicBlock&>(*I));
Root = SDB.CurRoot;
}