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llvm-project/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

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//===-- SelectionDAGISel.cpp - Implement the SelectionDAGISel class -------===//
//
// 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 implements the SelectionDAGISel class.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "isel"
#include "llvm/CodeGen/SelectionDAGISel.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
#include "llvm/Instructions.h"
#include "llvm/Intrinsics.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/CodeGen/SSARegMap.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/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include <map>
#include <iostream>
using namespace llvm;
#ifndef _NDEBUG
static cl::opt<bool>
ViewDAGs("view-isel-dags", cl::Hidden,
cl::desc("Pop up a window to show isel dags as they are selected"));
#else
static const bool ViewDAGS = 0;
#endif
namespace llvm {
//===--------------------------------------------------------------------===//
/// FunctionLoweringInfo - This contains information that is global to a
/// function that is used when lowering a region of the function.
class FunctionLoweringInfo {
public:
TargetLowering &TLI;
Function &Fn;
MachineFunction &MF;
SSARegMap *RegMap;
FunctionLoweringInfo(TargetLowering &TLI, Function &Fn,MachineFunction &MF);
/// MBBMap - A mapping from LLVM basic blocks to their machine code entry.
std::map<const BasicBlock*, MachineBasicBlock *> MBBMap;
/// ValueMap - Since we emit code for the function a basic block at a time,
/// we must remember which virtual registers hold the values for
/// cross-basic-block values.
std::map<const Value*, unsigned> ValueMap;
/// StaticAllocaMap - Keep track of frame indices for fixed sized allocas in
/// the entry block. This allows the allocas to be efficiently referenced
/// anywhere in the function.
std::map<const AllocaInst*, int> StaticAllocaMap;
/// BlockLocalArguments - If any arguments are only used in a single basic
/// block, and if the target can access the arguments without side-effects,
/// avoid emitting CopyToReg nodes for those arguments. This map keeps
/// track of which arguments are local to each BB.
std::multimap<BasicBlock*, std::pair<Argument*,
unsigned> > BlockLocalArguments;
unsigned MakeReg(MVT::ValueType VT) {
return RegMap->createVirtualRegister(TLI.getRegClassFor(VT));
}
unsigned CreateRegForValue(const Value *V) {
MVT::ValueType VT = TLI.getValueType(V->getType());
// The common case is that we will only create one register for this
// value. If we have that case, create and return the virtual register.
unsigned NV = TLI.getNumElements(VT);
if (NV == 1) {
// If we are promoting this value, pick the next largest supported type.
return MakeReg(TLI.getTypeToTransformTo(VT));
}
// If this value is represented with multiple target registers, make sure
// to create enough consequtive registers of the right (smaller) type.
unsigned NT = VT-1; // Find the type to use.
while (TLI.getNumElements((MVT::ValueType)NT) != 1)
--NT;
unsigned R = MakeReg((MVT::ValueType)NT);
for (unsigned i = 1; i != NV; ++i)
MakeReg((MVT::ValueType)NT);
return R;
}
unsigned InitializeRegForValue(const Value *V) {
unsigned &R = ValueMap[V];
assert(R == 0 && "Already initialized this value register!");
return R = CreateRegForValue(V);
}
};
}
/// isUsedOutsideOfDefiningBlock - Return true if this instruction is used by
/// PHI nodes or outside of the basic block that defines it.
static bool isUsedOutsideOfDefiningBlock(Instruction *I) {
if (isa<PHINode>(I)) return true;
BasicBlock *BB = I->getParent();
for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI != E; ++UI)
if (cast<Instruction>(*UI)->getParent() != BB || isa<PHINode>(*UI))
return true;
return false;
}
FunctionLoweringInfo::FunctionLoweringInfo(TargetLowering &tli,
Function &fn, MachineFunction &mf)
: TLI(tli), Fn(fn), MF(mf), RegMap(MF.getSSARegMap()) {
// Initialize the mapping of values to registers. This is only set up for
// instruction values that are used outside of the block that defines
// them.
for (Function::arg_iterator AI = Fn.arg_begin(), E = Fn.arg_end(); AI != E; ++AI)
InitializeRegForValue(AI);
Function::iterator BB = Fn.begin(), E = Fn.end();
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
if (AllocaInst *AI = dyn_cast<AllocaInst>(I))
if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(AI->getArraySize())) {
const Type *Ty = AI->getAllocatedType();
uint64_t TySize = TLI.getTargetData().getTypeSize(Ty);
unsigned Align = TLI.getTargetData().getTypeAlignment(Ty);
TySize *= CUI->getValue(); // Get total allocated size.
StaticAllocaMap[AI] =
MF.getFrameInfo()->CreateStackObject((unsigned)TySize, Align);
}
for (; BB != E; ++BB)
for (BasicBlock::iterator I = BB->begin(), e = BB->end(); I != e; ++I)
if (!I->use_empty() && isUsedOutsideOfDefiningBlock(I))
if (!isa<AllocaInst>(I) ||
!StaticAllocaMap.count(cast<AllocaInst>(I)))
InitializeRegForValue(I);
// Create an initial MachineBasicBlock for each LLVM BasicBlock in F. This
// also creates the initial PHI MachineInstrs, though none of the input
// operands are populated.
for (Function::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB) {
MachineBasicBlock *MBB = new MachineBasicBlock(BB);
MBBMap[BB] = MBB;
MF.getBasicBlockList().push_back(MBB);
// Create Machine PHI nodes for LLVM PHI nodes, lowering them as
// appropriate.
PHINode *PN;
for (BasicBlock::iterator I = BB->begin();
(PN = dyn_cast<PHINode>(I)); ++I)
if (!PN->use_empty()) {
unsigned NumElements =
TLI.getNumElements(TLI.getValueType(PN->getType()));
unsigned PHIReg = ValueMap[PN];
assert(PHIReg &&"PHI node does not have an assigned virtual register!");
for (unsigned i = 0; i != NumElements; ++i)
BuildMI(MBB, TargetInstrInfo::PHI, PN->getNumOperands(), PHIReg+i);
}
}
}
//===----------------------------------------------------------------------===//
/// SelectionDAGLowering - This is the common target-independent lowering
/// implementation that is parameterized by a TargetLowering object.
/// Also, targets can overload any lowering method.
///
namespace llvm {
class SelectionDAGLowering {
MachineBasicBlock *CurMBB;
std::map<const Value*, SDOperand> NodeMap;
/// PendingLoads - Loads are not emitted to the program immediately. We bunch
/// them up and then emit token factor nodes when possible. This allows us to
/// get simple disambiguation between loads without worrying about alias
/// analysis.
std::vector<SDOperand> PendingLoads;
public:
// TLI - This is information that describes the available target features we
// need for lowering. This indicates when operations are unavailable,
// implemented with a libcall, etc.
TargetLowering &TLI;
SelectionDAG &DAG;
const TargetData &TD;
/// FuncInfo - Information about the function as a whole.
///
FunctionLoweringInfo &FuncInfo;
SelectionDAGLowering(SelectionDAG &dag, TargetLowering &tli,
FunctionLoweringInfo &funcinfo)
: TLI(tli), DAG(dag), TD(DAG.getTarget().getTargetData()),
FuncInfo(funcinfo) {
}
/// getRoot - Return the current virtual root of the Selection DAG.
///
SDOperand getRoot() {
if (PendingLoads.empty())
return DAG.getRoot();
if (PendingLoads.size() == 1) {
SDOperand Root = PendingLoads[0];
DAG.setRoot(Root);
PendingLoads.clear();
return Root;
}
// Otherwise, we have to make a token factor node.
SDOperand Root = DAG.getNode(ISD::TokenFactor, MVT::Other, PendingLoads);
PendingLoads.clear();
DAG.setRoot(Root);
return Root;
}
void visit(Instruction &I) { visit(I.getOpcode(), I); }
void visit(unsigned Opcode, User &I) {
switch (Opcode) {
default: assert(0 && "Unknown instruction type encountered!");
abort();
// Build the switch statement using the Instruction.def file.
#define HANDLE_INST(NUM, OPCODE, CLASS) \
case Instruction::OPCODE:return visit##OPCODE((CLASS&)I);
#include "llvm/Instruction.def"
}
}
void setCurrentBasicBlock(MachineBasicBlock *MBB) { CurMBB = MBB; }
SDOperand getIntPtrConstant(uint64_t Val) {
return DAG.getConstant(Val, TLI.getPointerTy());
}
SDOperand getValue(const Value *V) {
SDOperand &N = NodeMap[V];
if (N.Val) return N;
MVT::ValueType VT = TLI.getValueType(V->getType());
if (Constant *C = const_cast<Constant*>(dyn_cast<Constant>(V)))
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
visit(CE->getOpcode(), *CE);
assert(N.Val && "visit didn't populate the ValueMap!");
return N;
} else if (GlobalValue *GV = dyn_cast<GlobalValue>(C)) {
return N = DAG.getGlobalAddress(GV, VT);
} else if (isa<ConstantPointerNull>(C)) {
return N = DAG.getConstant(0, TLI.getPointerTy());
} else if (isa<UndefValue>(C)) {
return N = DAG.getNode(ISD::UNDEF, VT);
} else if (ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
return N = DAG.getConstantFP(CFP->getValue(), VT);
} else {
// Canonicalize all constant ints to be unsigned.
return N = DAG.getConstant(cast<ConstantIntegral>(C)->getRawValue(),VT);
}
if (const AllocaInst *AI = dyn_cast<AllocaInst>(V)) {
std::map<const AllocaInst*, int>::iterator SI =
FuncInfo.StaticAllocaMap.find(AI);
if (SI != FuncInfo.StaticAllocaMap.end())
return DAG.getFrameIndex(SI->second, TLI.getPointerTy());
}
std::map<const Value*, unsigned>::const_iterator VMI =
FuncInfo.ValueMap.find(V);
assert(VMI != FuncInfo.ValueMap.end() && "Value not in map!");
return N = DAG.getCopyFromReg(VMI->second, VT, DAG.getEntryNode());
}
const SDOperand &setValue(const Value *V, SDOperand NewN) {
SDOperand &N = NodeMap[V];
assert(N.Val == 0 && "Already set a value for this node!");
return N = NewN;
}
// Terminator instructions.
void visitRet(ReturnInst &I);
void visitBr(BranchInst &I);
void visitUnreachable(UnreachableInst &I) { /* noop */ }
// These all get lowered before this pass.
void visitSwitch(SwitchInst &I) { assert(0 && "TODO"); }
void visitInvoke(InvokeInst &I) { assert(0 && "TODO"); }
void visitUnwind(UnwindInst &I) { assert(0 && "TODO"); }
//
void visitBinary(User &I, unsigned Opcode);
void visitAdd(User &I) { visitBinary(I, ISD::ADD); }
void visitSub(User &I);
void visitMul(User &I) { visitBinary(I, ISD::MUL); }
void visitDiv(User &I) {
visitBinary(I, I.getType()->isUnsigned() ? ISD::UDIV : ISD::SDIV);
}
void visitRem(User &I) {
visitBinary(I, I.getType()->isUnsigned() ? ISD::UREM : ISD::SREM);
}
void visitAnd(User &I) { visitBinary(I, ISD::AND); }
void visitOr (User &I) { visitBinary(I, ISD::OR); }
void visitXor(User &I) { visitBinary(I, ISD::XOR); }
void visitShl(User &I) { visitBinary(I, ISD::SHL); }
void visitShr(User &I) {
visitBinary(I, I.getType()->isUnsigned() ? ISD::SRL : ISD::SRA);
}
void visitSetCC(User &I, ISD::CondCode SignedOpc, ISD::CondCode UnsignedOpc);
void visitSetEQ(User &I) { visitSetCC(I, ISD::SETEQ, ISD::SETEQ); }
void visitSetNE(User &I) { visitSetCC(I, ISD::SETNE, ISD::SETNE); }
void visitSetLE(User &I) { visitSetCC(I, ISD::SETLE, ISD::SETULE); }
void visitSetGE(User &I) { visitSetCC(I, ISD::SETGE, ISD::SETUGE); }
void visitSetLT(User &I) { visitSetCC(I, ISD::SETLT, ISD::SETULT); }
void visitSetGT(User &I) { visitSetCC(I, ISD::SETGT, ISD::SETUGT); }
void visitGetElementPtr(User &I);
void visitCast(User &I);
void visitSelect(User &I);
//
void visitMalloc(MallocInst &I);
void visitFree(FreeInst &I);
void visitAlloca(AllocaInst &I);
void visitLoad(LoadInst &I);
void visitStore(StoreInst &I);
void visitPHI(PHINode &I) { } // PHI nodes are handled specially.
void visitCall(CallInst &I);
void visitVAStart(CallInst &I);
void visitVANext(VANextInst &I);
void visitVAArg(VAArgInst &I);
void visitVAEnd(CallInst &I);
void visitVACopy(CallInst &I);
void visitFrameReturnAddress(CallInst &I, bool isFrameAddress);
void visitMemIntrinsic(CallInst &I, unsigned Op);
void visitUserOp1(Instruction &I) {
assert(0 && "UserOp1 should not exist at instruction selection time!");
abort();
}
void visitUserOp2(Instruction &I) {
assert(0 && "UserOp2 should not exist at instruction selection time!");
abort();
}
};
} // end namespace llvm
void SelectionDAGLowering::visitRet(ReturnInst &I) {
if (I.getNumOperands() == 0) {
DAG.setRoot(DAG.getNode(ISD::RET, MVT::Other, getRoot()));
return;
}
SDOperand Op1 = getValue(I.getOperand(0));
MVT::ValueType TmpVT;
switch (Op1.getValueType()) {
default: assert(0 && "Unknown value type!");
case MVT::i1:
case MVT::i8:
case MVT::i16:
case MVT::i32:
// If this is a machine where 32-bits is legal or expanded, promote to
// 32-bits, otherwise, promote to 64-bits.
if (TLI.getTypeAction(MVT::i32) == TargetLowering::Promote)
TmpVT = TLI.getTypeToTransformTo(MVT::i32);
else
TmpVT = MVT::i32;
// Extend integer types to result type.
if (I.getOperand(0)->getType()->isSigned())
Op1 = DAG.getNode(ISD::SIGN_EXTEND, TmpVT, Op1);
else
Op1 = DAG.getNode(ISD::ZERO_EXTEND, TmpVT, Op1);
break;
case MVT::f32:
// Extend float to double.
Op1 = DAG.getNode(ISD::FP_EXTEND, MVT::f64, Op1);
break;
case MVT::i64:
case MVT::f64:
break; // No extension needed!
}
DAG.setRoot(DAG.getNode(ISD::RET, MVT::Other, getRoot(), Op1));
}
void SelectionDAGLowering::visitBr(BranchInst &I) {
// Update machine-CFG edges.
MachineBasicBlock *Succ0MBB = FuncInfo.MBBMap[I.getSuccessor(0)];
// Figure out which block is immediately after the current one.
MachineBasicBlock *NextBlock = 0;
MachineFunction::iterator BBI = CurMBB;
if (++BBI != CurMBB->getParent()->end())
NextBlock = BBI;
if (I.isUnconditional()) {
// If this is not a fall-through branch, emit the branch.
if (Succ0MBB != NextBlock)
DAG.setRoot(DAG.getNode(ISD::BR, MVT::Other, getRoot(),
DAG.getBasicBlock(Succ0MBB)));
} else {
MachineBasicBlock *Succ1MBB = FuncInfo.MBBMap[I.getSuccessor(1)];
SDOperand Cond = getValue(I.getCondition());
if (Succ1MBB == NextBlock) {
// If the condition is false, fall through. This means we should branch
// if the condition is true to Succ #0.
DAG.setRoot(DAG.getNode(ISD::BRCOND, MVT::Other, getRoot(),
Cond, DAG.getBasicBlock(Succ0MBB)));
} else if (Succ0MBB == NextBlock) {
// If the condition is true, fall through. This means we should branch if
// the condition is false to Succ #1. Invert the condition first.
SDOperand True = DAG.getConstant(1, Cond.getValueType());
Cond = DAG.getNode(ISD::XOR, Cond.getValueType(), Cond, True);
DAG.setRoot(DAG.getNode(ISD::BRCOND, MVT::Other, getRoot(),
Cond, DAG.getBasicBlock(Succ1MBB)));
} else {
std::vector<SDOperand> Ops;
Ops.push_back(getRoot());
Ops.push_back(Cond);
Ops.push_back(DAG.getBasicBlock(Succ0MBB));
Ops.push_back(DAG.getBasicBlock(Succ1MBB));
DAG.setRoot(DAG.getNode(ISD::BRCONDTWOWAY, MVT::Other, Ops));
}
}
}
void SelectionDAGLowering::visitSub(User &I) {
// -0.0 - X --> fneg
if (ConstantFP *CFP = dyn_cast<ConstantFP>(I.getOperand(0)))
if (CFP->isExactlyValue(-0.0)) {
SDOperand Op2 = getValue(I.getOperand(1));
setValue(&I, DAG.getNode(ISD::FNEG, Op2.getValueType(), Op2));
return;
}
visitBinary(I, ISD::SUB);
}
void SelectionDAGLowering::visitBinary(User &I, unsigned Opcode) {
SDOperand Op1 = getValue(I.getOperand(0));
SDOperand Op2 = getValue(I.getOperand(1));
if (isa<ShiftInst>(I))
Op2 = DAG.getNode(ISD::ZERO_EXTEND, TLI.getShiftAmountTy(), Op2);
setValue(&I, DAG.getNode(Opcode, Op1.getValueType(), Op1, Op2));
}
void SelectionDAGLowering::visitSetCC(User &I,ISD::CondCode SignedOpcode,
ISD::CondCode UnsignedOpcode) {
SDOperand Op1 = getValue(I.getOperand(0));
SDOperand Op2 = getValue(I.getOperand(1));
ISD::CondCode Opcode = SignedOpcode;
if (I.getOperand(0)->getType()->isUnsigned())
Opcode = UnsignedOpcode;
setValue(&I, DAG.getSetCC(Opcode, MVT::i1, Op1, Op2));
}
void SelectionDAGLowering::visitSelect(User &I) {
SDOperand Cond = getValue(I.getOperand(0));
SDOperand TrueVal = getValue(I.getOperand(1));
SDOperand FalseVal = getValue(I.getOperand(2));
setValue(&I, DAG.getNode(ISD::SELECT, TrueVal.getValueType(), Cond,
TrueVal, FalseVal));
}
void SelectionDAGLowering::visitCast(User &I) {
SDOperand N = getValue(I.getOperand(0));
MVT::ValueType SrcTy = TLI.getValueType(I.getOperand(0)->getType());
MVT::ValueType DestTy = TLI.getValueType(I.getType());
if (N.getValueType() == DestTy) {
setValue(&I, N); // noop cast.
} else if (isInteger(SrcTy)) {
if (isInteger(DestTy)) { // Int -> Int cast
if (DestTy < SrcTy) // Truncating cast?
setValue(&I, DAG.getNode(ISD::TRUNCATE, DestTy, N));
else if (I.getOperand(0)->getType()->isSigned())
setValue(&I, DAG.getNode(ISD::SIGN_EXTEND, DestTy, N));
else
setValue(&I, DAG.getNode(ISD::ZERO_EXTEND, DestTy, N));
} else { // Int -> FP cast
if (I.getOperand(0)->getType()->isSigned())
setValue(&I, DAG.getNode(ISD::SINT_TO_FP, DestTy, N));
else
setValue(&I, DAG.getNode(ISD::UINT_TO_FP, DestTy, N));
}
} else {
assert(isFloatingPoint(SrcTy) && "Unknown value type!");
if (isFloatingPoint(DestTy)) { // FP -> FP cast
if (DestTy < SrcTy) // Rounding cast?
setValue(&I, DAG.getNode(ISD::FP_ROUND, DestTy, N));
else
setValue(&I, DAG.getNode(ISD::FP_EXTEND, DestTy, N));
} else { // FP -> Int cast.
if (I.getType()->isSigned())
setValue(&I, DAG.getNode(ISD::FP_TO_SINT, DestTy, N));
else
setValue(&I, DAG.getNode(ISD::FP_TO_UINT, DestTy, N));
}
}
}
void SelectionDAGLowering::visitGetElementPtr(User &I) {
SDOperand N = getValue(I.getOperand(0));
const Type *Ty = I.getOperand(0)->getType();
const Type *UIntPtrTy = TD.getIntPtrType();
for (GetElementPtrInst::op_iterator OI = I.op_begin()+1, E = I.op_end();
OI != E; ++OI) {
Value *Idx = *OI;
if (const StructType *StTy = dyn_cast<StructType> (Ty)) {
unsigned Field = cast<ConstantUInt>(Idx)->getValue();
if (Field) {
// N = N + Offset
uint64_t Offset = TD.getStructLayout(StTy)->MemberOffsets[Field];
N = DAG.getNode(ISD::ADD, N.getValueType(), N,
getIntPtrConstant(Offset));
}
Ty = StTy->getElementType(Field);
} else {
Ty = cast<SequentialType>(Ty)->getElementType();
if (!isa<Constant>(Idx) || !cast<Constant>(Idx)->isNullValue()) {
// N = N + Idx * ElementSize;
uint64_t ElementSize = TD.getTypeSize(Ty);
SDOperand IdxN = getValue(Idx), Scale = getIntPtrConstant(ElementSize);
// If the index is smaller or larger than intptr_t, truncate or extend
// it.
if (IdxN.getValueType() < Scale.getValueType()) {
if (Idx->getType()->isSigned())
IdxN = DAG.getNode(ISD::SIGN_EXTEND, Scale.getValueType(), IdxN);
else
IdxN = DAG.getNode(ISD::ZERO_EXTEND, Scale.getValueType(), IdxN);
} else if (IdxN.getValueType() > Scale.getValueType())
IdxN = DAG.getNode(ISD::TRUNCATE, Scale.getValueType(), IdxN);
IdxN = DAG.getNode(ISD::MUL, N.getValueType(), IdxN, Scale);
N = DAG.getNode(ISD::ADD, N.getValueType(), N, IdxN);
}
}
}
setValue(&I, N);
}
void SelectionDAGLowering::visitAlloca(AllocaInst &I) {
// If this is a fixed sized alloca in the entry block of the function,
// allocate it statically on the stack.
if (FuncInfo.StaticAllocaMap.count(&I))
return; // getValue will auto-populate this.
const Type *Ty = I.getAllocatedType();
uint64_t TySize = TLI.getTargetData().getTypeSize(Ty);
unsigned Align = TLI.getTargetData().getTypeAlignment(Ty);
SDOperand AllocSize = getValue(I.getArraySize());
MVT::ValueType IntPtr = TLI.getPointerTy();
if (IntPtr < AllocSize.getValueType())
AllocSize = DAG.getNode(ISD::TRUNCATE, IntPtr, AllocSize);
else if (IntPtr > AllocSize.getValueType())
AllocSize = DAG.getNode(ISD::ZERO_EXTEND, IntPtr, AllocSize);
AllocSize = DAG.getNode(ISD::MUL, IntPtr, AllocSize,
getIntPtrConstant(TySize));
// Handle alignment. If the requested alignment is less than or equal to the
// stack alignment, ignore it and round the size of the allocation up to the
// stack alignment size. If the size is greater than the stack alignment, we
// note this in the DYNAMIC_STACKALLOC node.
unsigned StackAlign =
TLI.getTargetMachine().getFrameInfo()->getStackAlignment();
if (Align <= StackAlign) {
Align = 0;
// Add SA-1 to the size.
AllocSize = DAG.getNode(ISD::ADD, AllocSize.getValueType(), AllocSize,
getIntPtrConstant(StackAlign-1));
// Mask out the low bits for alignment purposes.
AllocSize = DAG.getNode(ISD::AND, AllocSize.getValueType(), AllocSize,
getIntPtrConstant(~(uint64_t)(StackAlign-1)));
}
SDOperand DSA = DAG.getNode(ISD::DYNAMIC_STACKALLOC, AllocSize.getValueType(),
getRoot(), AllocSize,
getIntPtrConstant(Align));
DAG.setRoot(setValue(&I, DSA).getValue(1));
// Inform the Frame Information that we have just allocated a variable-sized
// object.
CurMBB->getParent()->getFrameInfo()->CreateVariableSizedObject();
}
void SelectionDAGLowering::visitLoad(LoadInst &I) {
SDOperand Ptr = getValue(I.getOperand(0));
SDOperand Root;
if (I.isVolatile())
Root = getRoot();
else {
// Do not serialize non-volatile loads against each other.
Root = DAG.getRoot();
}
SDOperand L = DAG.getLoad(TLI.getValueType(I.getType()), Root, Ptr);
setValue(&I, L);
if (I.isVolatile())
DAG.setRoot(L.getValue(1));
else
PendingLoads.push_back(L.getValue(1));
}
void SelectionDAGLowering::visitStore(StoreInst &I) {
Value *SrcV = I.getOperand(0);
SDOperand Src = getValue(SrcV);
SDOperand Ptr = getValue(I.getOperand(1));
DAG.setRoot(DAG.getNode(ISD::STORE, MVT::Other, getRoot(), Src, Ptr));
}
void SelectionDAGLowering::visitCall(CallInst &I) {
const char *RenameFn = 0;
if (Function *F = I.getCalledFunction())
if (F->isExternal())
switch (F->getIntrinsicID()) {
case 0: // Not an LLVM intrinsic.
if (F->getName() == "fabs" || F->getName() == "fabsf") {
if (I.getNumOperands() == 2 && // Basic sanity checks.
I.getOperand(1)->getType()->isFloatingPoint() &&
I.getType() == I.getOperand(1)->getType()) {
SDOperand Tmp = getValue(I.getOperand(1));
setValue(&I, DAG.getNode(ISD::FABS, Tmp.getValueType(), Tmp));
return;
}
}
break;
case Intrinsic::vastart: visitVAStart(I); return;
case Intrinsic::vaend: visitVAEnd(I); return;
case Intrinsic::vacopy: visitVACopy(I); return;
case Intrinsic::returnaddress: visitFrameReturnAddress(I, false); return;
case Intrinsic::frameaddress: visitFrameReturnAddress(I, true); return;
default:
// FIXME: IMPLEMENT THESE.
// readport, writeport, readio, writeio
assert(0 && "This intrinsic is not implemented yet!");
return;
case Intrinsic::setjmp: RenameFn = "setjmp"; break;
case Intrinsic::longjmp: RenameFn = "longjmp"; break;
case Intrinsic::memcpy: visitMemIntrinsic(I, ISD::MEMCPY); return;
case Intrinsic::memset: visitMemIntrinsic(I, ISD::MEMSET); return;
case Intrinsic::memmove: visitMemIntrinsic(I, ISD::MEMMOVE); return;
case Intrinsic::isunordered:
setValue(&I, DAG.getSetCC(ISD::SETUO, MVT::i1,getValue(I.getOperand(1)),
getValue(I.getOperand(2))));
return;
case Intrinsic::pcmarker: {
SDOperand Num = getValue(I.getOperand(1));
DAG.setRoot(DAG.getNode(ISD::PCMARKER, MVT::Other, getRoot(), Num));
return;
}
}
SDOperand Callee;
if (!RenameFn)
Callee = getValue(I.getOperand(0));
else
Callee = DAG.getExternalSymbol(RenameFn, TLI.getPointerTy());
std::vector<std::pair<SDOperand, const Type*> > Args;
for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i) {
Value *Arg = I.getOperand(i);
SDOperand ArgNode = getValue(Arg);
Args.push_back(std::make_pair(ArgNode, Arg->getType()));
}
const PointerType *PT = cast<PointerType>(I.getCalledValue()->getType());
const FunctionType *FTy = cast<FunctionType>(PT->getElementType());
std::pair<SDOperand,SDOperand> Result =
TLI.LowerCallTo(getRoot(), I.getType(), FTy->isVarArg(), Callee, Args, DAG);
if (I.getType() != Type::VoidTy)
setValue(&I, Result.first);
DAG.setRoot(Result.second);
}
void SelectionDAGLowering::visitMalloc(MallocInst &I) {
SDOperand Src = getValue(I.getOperand(0));
MVT::ValueType IntPtr = TLI.getPointerTy();
if (IntPtr < Src.getValueType())
Src = DAG.getNode(ISD::TRUNCATE, IntPtr, Src);
else if (IntPtr > Src.getValueType())
Src = DAG.getNode(ISD::ZERO_EXTEND, IntPtr, Src);
// Scale the source by the type size.
uint64_t ElementSize = TD.getTypeSize(I.getType()->getElementType());
Src = DAG.getNode(ISD::MUL, Src.getValueType(),
Src, getIntPtrConstant(ElementSize));
std::vector<std::pair<SDOperand, const Type*> > Args;
Args.push_back(std::make_pair(Src, TLI.getTargetData().getIntPtrType()));
std::pair<SDOperand,SDOperand> Result =
TLI.LowerCallTo(getRoot(), I.getType(), false,
DAG.getExternalSymbol("malloc", IntPtr),
Args, DAG);
setValue(&I, Result.first); // Pointers always fit in registers
DAG.setRoot(Result.second);
}
void SelectionDAGLowering::visitFree(FreeInst &I) {
std::vector<std::pair<SDOperand, const Type*> > Args;
Args.push_back(std::make_pair(getValue(I.getOperand(0)),
TLI.getTargetData().getIntPtrType()));
MVT::ValueType IntPtr = TLI.getPointerTy();
std::pair<SDOperand,SDOperand> Result =
TLI.LowerCallTo(getRoot(), Type::VoidTy, false,
DAG.getExternalSymbol("free", IntPtr), Args, DAG);
DAG.setRoot(Result.second);
}
std::pair<SDOperand, SDOperand>
TargetLowering::LowerVAStart(SDOperand Chain, SelectionDAG &DAG) {
// We have no sane default behavior, just emit a useful error message and bail
// out.
std::cerr << "Variable arguments handling not implemented on this target!\n";
abort();
return std::make_pair(SDOperand(), SDOperand());
}
SDOperand TargetLowering::LowerVAEnd(SDOperand Chain, SDOperand L,
SelectionDAG &DAG) {
// Default to a noop.
return Chain;
}
std::pair<SDOperand,SDOperand>
TargetLowering::LowerVACopy(SDOperand Chain, SDOperand L, SelectionDAG &DAG) {
// Default to returning the input list.
return std::make_pair(L, Chain);
}
std::pair<SDOperand,SDOperand>
TargetLowering::LowerVAArgNext(bool isVANext, SDOperand Chain, SDOperand VAList,
const Type *ArgTy, SelectionDAG &DAG) {
// We have no sane default behavior, just emit a useful error message and bail
// out.
std::cerr << "Variable arguments handling not implemented on this target!\n";
abort();
return std::make_pair(SDOperand(), SDOperand());
}
void SelectionDAGLowering::visitVAStart(CallInst &I) {
std::pair<SDOperand,SDOperand> Result = TLI.LowerVAStart(getRoot(), DAG);
setValue(&I, Result.first);
DAG.setRoot(Result.second);
}
void SelectionDAGLowering::visitVAArg(VAArgInst &I) {
std::pair<SDOperand,SDOperand> Result =
TLI.LowerVAArgNext(false, getRoot(), getValue(I.getOperand(0)),
I.getType(), DAG);
setValue(&I, Result.first);
DAG.setRoot(Result.second);
}
void SelectionDAGLowering::visitVANext(VANextInst &I) {
std::pair<SDOperand,SDOperand> Result =
TLI.LowerVAArgNext(true, getRoot(), getValue(I.getOperand(0)),
I.getArgType(), DAG);
setValue(&I, Result.first);
DAG.setRoot(Result.second);
}
void SelectionDAGLowering::visitVAEnd(CallInst &I) {
DAG.setRoot(TLI.LowerVAEnd(getRoot(), getValue(I.getOperand(1)), DAG));
}
void SelectionDAGLowering::visitVACopy(CallInst &I) {
std::pair<SDOperand,SDOperand> Result =
TLI.LowerVACopy(getRoot(), getValue(I.getOperand(1)), DAG);
setValue(&I, Result.first);
DAG.setRoot(Result.second);
}
// It is always conservatively correct for llvm.returnaddress and
// llvm.frameaddress to return 0.
std::pair<SDOperand, SDOperand>
TargetLowering::LowerFrameReturnAddress(bool isFrameAddr, SDOperand Chain,
unsigned Depth, SelectionDAG &DAG) {
return std::make_pair(DAG.getConstant(0, getPointerTy()), Chain);
}
SDOperand TargetLowering::LowerOperation(SDOperand Op) {
assert(0 && "LowerOperation not implemented for this target!");
abort();
return SDOperand();
}
void SelectionDAGLowering::visitFrameReturnAddress(CallInst &I, bool isFrame) {
unsigned Depth = (unsigned)cast<ConstantUInt>(I.getOperand(1))->getValue();
std::pair<SDOperand,SDOperand> Result =
TLI.LowerFrameReturnAddress(isFrame, getRoot(), Depth, DAG);
setValue(&I, Result.first);
DAG.setRoot(Result.second);
}
void SelectionDAGLowering::visitMemIntrinsic(CallInst &I, unsigned Op) {
std::vector<SDOperand> Ops;
Ops.push_back(getRoot());
Ops.push_back(getValue(I.getOperand(1)));
Ops.push_back(getValue(I.getOperand(2)));
Ops.push_back(getValue(I.getOperand(3)));
Ops.push_back(getValue(I.getOperand(4)));
DAG.setRoot(DAG.getNode(Op, MVT::Other, Ops));
}
//===----------------------------------------------------------------------===//
// SelectionDAGISel code
//===----------------------------------------------------------------------===//
unsigned SelectionDAGISel::MakeReg(MVT::ValueType VT) {
return RegMap->createVirtualRegister(TLI.getRegClassFor(VT));
}
bool SelectionDAGISel::runOnFunction(Function &Fn) {
MachineFunction &MF = MachineFunction::construct(&Fn, TLI.getTargetMachine());
RegMap = MF.getSSARegMap();
DEBUG(std::cerr << "\n\n\n=== " << Fn.getName() << "\n");
FunctionLoweringInfo FuncInfo(TLI, Fn, MF);
for (Function::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I)
SelectBasicBlock(I, MF, FuncInfo);
return true;
}
SDOperand SelectionDAGISel::
CopyValueToVirtualRegister(SelectionDAGLowering &SDL, Value *V, unsigned Reg) {
SelectionDAG &DAG = SDL.DAG;
SDOperand Op = SDL.getValue(V);
assert((Op.getOpcode() != ISD::CopyFromReg ||
cast<RegSDNode>(Op)->getReg() != Reg) &&
"Copy from a reg to the same reg!");
return DAG.getCopyToReg(SDL.getRoot(), Op, Reg);
}
/// IsOnlyUsedInOneBasicBlock - If the specified argument is only used in a
/// single basic block, return that block. Otherwise, return a null pointer.
static BasicBlock *IsOnlyUsedInOneBasicBlock(Argument *A) {
if (A->use_empty()) return 0;
BasicBlock *BB = cast<Instruction>(A->use_back())->getParent();
for (Argument::use_iterator UI = A->use_begin(), E = A->use_end(); UI != E;
++UI)
if (isa<PHINode>(*UI) || cast<Instruction>(*UI)->getParent() != BB)
return 0; // Disagreement among the users?
// Okay, there is a single BB user. Only permit this optimization if this is
// the entry block, otherwise, we might sink argument loads into loops and
// stuff. Later, when we have global instruction selection, this won't be an
// issue clearly.
if (BB == BB->getParent()->begin())
return BB;
return 0;
}
void SelectionDAGISel::
LowerArguments(BasicBlock *BB, SelectionDAGLowering &SDL,
std::vector<SDOperand> &UnorderedChains) {
// If this is the entry block, emit arguments.
Function &F = *BB->getParent();
FunctionLoweringInfo &FuncInfo = SDL.FuncInfo;
if (BB == &F.front()) {
SDOperand OldRoot = SDL.DAG.getRoot();
std::vector<SDOperand> Args = TLI.LowerArguments(F, SDL.DAG);
// If there were side effects accessing the argument list, do not do
// anything special.
if (OldRoot != SDL.DAG.getRoot()) {
unsigned a = 0;
for (Function::arg_iterator AI = F.arg_begin(), E = F.arg_end();
AI != E; ++AI,++a)
if (!AI->use_empty()) {
SDL.setValue(AI, Args[a]);
SDOperand Copy =
CopyValueToVirtualRegister(SDL, AI, FuncInfo.ValueMap[AI]);
UnorderedChains.push_back(Copy);
}
} else {
// Otherwise, if any argument is only accessed in a single basic block,
// emit that argument only to that basic block.
unsigned a = 0;
for (Function::arg_iterator AI = F.arg_begin(), E = F.arg_end();
AI != E; ++AI,++a)
if (!AI->use_empty()) {
if (BasicBlock *BBU = IsOnlyUsedInOneBasicBlock(AI)) {
FuncInfo.BlockLocalArguments.insert(std::make_pair(BBU,
std::make_pair(AI, a)));
} else {
SDL.setValue(AI, Args[a]);
SDOperand Copy =
CopyValueToVirtualRegister(SDL, AI, FuncInfo.ValueMap[AI]);
UnorderedChains.push_back(Copy);
}
}
}
}
// See if there are any block-local arguments that need to be emitted in this
// block.
if (!FuncInfo.BlockLocalArguments.empty()) {
std::multimap<BasicBlock*, std::pair<Argument*, unsigned> >::iterator BLAI =
FuncInfo.BlockLocalArguments.lower_bound(BB);
if (BLAI != FuncInfo.BlockLocalArguments.end() && BLAI->first == BB) {
// Lower the arguments into this block.
std::vector<SDOperand> Args = TLI.LowerArguments(F, SDL.DAG);
// Set up the value mapping for the local arguments.
for (; BLAI != FuncInfo.BlockLocalArguments.end() && BLAI->first == BB;
++BLAI)
SDL.setValue(BLAI->second.first, Args[BLAI->second.second]);
// Any dead arguments will just be ignored here.
}
}
}
void SelectionDAGISel::BuildSelectionDAG(SelectionDAG &DAG, BasicBlock *LLVMBB,
std::vector<std::pair<MachineInstr*, unsigned> > &PHINodesToUpdate,
FunctionLoweringInfo &FuncInfo) {
SelectionDAGLowering SDL(DAG, TLI, FuncInfo);
std::vector<SDOperand> UnorderedChains;
// Lower any arguments needed in this block.
LowerArguments(LLVMBB, SDL, UnorderedChains);
BB = FuncInfo.MBBMap[LLVMBB];
SDL.setCurrentBasicBlock(BB);
// Lower all of the non-terminator instructions.
for (BasicBlock::iterator I = LLVMBB->begin(), E = --LLVMBB->end();
I != E; ++I)
SDL.visit(*I);
// Ensure that all instructions which are used outside of their defining
// blocks are available as virtual registers.
for (BasicBlock::iterator I = LLVMBB->begin(), E = LLVMBB->end(); I != E;++I)
if (!I->use_empty() && !isa<PHINode>(I)) {
std::map<const Value*, unsigned>::iterator VMI =FuncInfo.ValueMap.find(I);
if (VMI != FuncInfo.ValueMap.end())
UnorderedChains.push_back(
CopyValueToVirtualRegister(SDL, I, VMI->second));
}
// Handle PHI nodes in successor blocks. Emit code into the SelectionDAG to
// ensure constants are generated when needed. Remember the virtual registers
// that need to be added to the Machine PHI nodes as input. We cannot just
// directly add them, because expansion might result in multiple MBB's for one
// BB. As such, the start of the BB might correspond to a different MBB than
// the end.
//
// Emit constants only once even if used by multiple PHI nodes.
std::map<Constant*, unsigned> ConstantsOut;
// Check successor nodes PHI nodes that expect a constant to be available from
// this block.
TerminatorInst *TI = LLVMBB->getTerminator();
for (unsigned succ = 0, e = TI->getNumSuccessors(); succ != e; ++succ) {
BasicBlock *SuccBB = TI->getSuccessor(succ);
MachineBasicBlock::iterator MBBI = FuncInfo.MBBMap[SuccBB]->begin();
PHINode *PN;
// At this point we know that there is a 1-1 correspondence between LLVM PHI
// nodes and Machine PHI nodes, but the incoming operands have not been
// emitted yet.
for (BasicBlock::iterator I = SuccBB->begin();
(PN = dyn_cast<PHINode>(I)); ++I)
if (!PN->use_empty()) {
unsigned Reg;
Value *PHIOp = PN->getIncomingValueForBlock(LLVMBB);
if (Constant *C = dyn_cast<Constant>(PHIOp)) {
unsigned &RegOut = ConstantsOut[C];
if (RegOut == 0) {
RegOut = FuncInfo.CreateRegForValue(C);
UnorderedChains.push_back(
CopyValueToVirtualRegister(SDL, C, RegOut));
}
Reg = RegOut;
} else {
Reg = FuncInfo.ValueMap[PHIOp];
if (Reg == 0) {
assert(isa<AllocaInst>(PHIOp) &&
FuncInfo.StaticAllocaMap.count(cast<AllocaInst>(PHIOp)) &&
"Didn't codegen value into a register!??");
Reg = FuncInfo.CreateRegForValue(PHIOp);
UnorderedChains.push_back(
CopyValueToVirtualRegister(SDL, PHIOp, Reg));
}
}
// Remember that this register needs to added to the machine PHI node as
// the input for this MBB.
unsigned NumElements =
TLI.getNumElements(TLI.getValueType(PN->getType()));
for (unsigned i = 0, e = NumElements; i != e; ++i)
PHINodesToUpdate.push_back(std::make_pair(MBBI++, Reg+i));
}
}
ConstantsOut.clear();
// Turn all of the unordered chains into one factored node.
if (!UnorderedChains.empty()) {
UnorderedChains.push_back(SDL.getRoot());
DAG.setRoot(DAG.getNode(ISD::TokenFactor, MVT::Other, UnorderedChains));
}
// Lower the terminator after the copies are emitted.
SDL.visit(*LLVMBB->getTerminator());
// Make sure the root of the DAG is up-to-date.
DAG.setRoot(SDL.getRoot());
}
void SelectionDAGISel::SelectBasicBlock(BasicBlock *LLVMBB, MachineFunction &MF,
FunctionLoweringInfo &FuncInfo) {
SelectionDAG DAG(TLI, MF);
CurDAG = &DAG;
std::vector<std::pair<MachineInstr*, unsigned> > PHINodesToUpdate;
// First step, lower LLVM code to some DAG. This DAG may use operations and
// types that are not supported by the target.
BuildSelectionDAG(DAG, LLVMBB, PHINodesToUpdate, FuncInfo);
DEBUG(std::cerr << "Lowered selection DAG:\n");
DEBUG(DAG.dump());
// Second step, hack on the DAG until it only uses operations and types that
// the target supports.
DAG.Legalize();
DEBUG(std::cerr << "Legalized selection DAG:\n");
DEBUG(DAG.dump());
// Third, instruction select all of the operations to machine code, adding the
// code to the MachineBasicBlock.
InstructionSelectBasicBlock(DAG);
if (ViewDAGs) DAG.viewGraph();
DEBUG(std::cerr << "Selected machine code:\n");
DEBUG(BB->dump());
// Next, now that we know what the last MBB the LLVM BB expanded is, update
// PHI nodes in successors.
for (unsigned i = 0, e = PHINodesToUpdate.size(); i != e; ++i) {
MachineInstr *PHI = PHINodesToUpdate[i].first;
assert(PHI->getOpcode() == TargetInstrInfo::PHI &&
"This is not a machine PHI node that we are updating!");
PHI->addRegOperand(PHINodesToUpdate[i].second);
PHI->addMachineBasicBlockOperand(BB);
}
// Finally, add the CFG edges from the last selected MBB to the successor
// MBBs.
TerminatorInst *TI = LLVMBB->getTerminator();
for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i) {
MachineBasicBlock *Succ0MBB = FuncInfo.MBBMap[TI->getSuccessor(i)];
BB->addSuccessor(Succ0MBB);
}
}
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