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llvm-6502/lib/Target/X86/X86ISelSimple.cpp
Chris Lattner 55f6fab9f1 Don't emit unneccesary branch instructions! 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@5328 91177308-0d34-0410-b5e6-96231b3b80d8
2003-01-16 18:07:23 +00:00

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//===-- InstSelectSimple.cpp - A simple instruction selector for x86 ------===//
//
// This file defines a simple peephole instruction selector for the x86 target
//
//===----------------------------------------------------------------------===//
#include "X86.h"
#include "X86InstrInfo.h"
#include "X86InstrBuilder.h"
#include "llvm/Function.h"
#include "llvm/iTerminators.h"
#include "llvm/iOperators.h"
#include "llvm/iOther.h"
#include "llvm/iPHINode.h"
#include "llvm/iMemory.h"
#include "llvm/Type.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Constants.h"
#include "llvm/Pass.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/SSARegMap.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineConstantPool.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Support/InstVisitor.h"
#include "llvm/Target/MRegisterInfo.h"
#include <map>
/// BMI - A special BuildMI variant that takes an iterator to insert the
/// instruction at as well as a basic block.
/// this is the version for when you have a destination register in mind.
inline static MachineInstrBuilder BMI(MachineBasicBlock *MBB,
MachineBasicBlock::iterator &I,
MachineOpCode Opcode,
unsigned NumOperands,
unsigned DestReg) {
assert(I >= MBB->begin() && I <= MBB->end() && "Bad iterator!");
MachineInstr *MI = new MachineInstr(Opcode, NumOperands+1, true, true);
I = MBB->insert(I, MI)+1;
return MachineInstrBuilder(MI).addReg(DestReg, MOTy::Def);
}
/// BMI - A special BuildMI variant that takes an iterator to insert the
/// instruction at as well as a basic block.
inline static MachineInstrBuilder BMI(MachineBasicBlock *MBB,
MachineBasicBlock::iterator &I,
MachineOpCode Opcode,
unsigned NumOperands) {
assert(I > MBB->begin() && I <= MBB->end() && "Bad iterator!");
MachineInstr *MI = new MachineInstr(Opcode, NumOperands, true, true);
I = MBB->insert(I, MI)+1;
return MachineInstrBuilder(MI);
}
namespace {
struct ISel : public FunctionPass, InstVisitor<ISel> {
TargetMachine &TM;
MachineFunction *F; // The function we are compiling into
MachineBasicBlock *BB; // The current MBB we are compiling
std::map<Value*, unsigned> RegMap; // Mapping between Val's and SSA Regs
// MBBMap - Mapping between LLVM BB -> Machine BB
std::map<const BasicBlock*, MachineBasicBlock*> MBBMap;
ISel(TargetMachine &tm) : TM(tm), F(0), BB(0) {}
/// runOnFunction - Top level implementation of instruction selection for
/// the entire function.
///
bool runOnFunction(Function &Fn) {
F = &MachineFunction::construct(&Fn, TM);
// Create all of the machine basic blocks for the function...
for (Function::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I)
F->getBasicBlockList().push_back(MBBMap[I] = new MachineBasicBlock(I));
BB = &F->front();
LoadArgumentsToVirtualRegs(Fn);
// Instruction select everything except PHI nodes
visit(Fn);
// Select the PHI nodes
SelectPHINodes();
RegMap.clear();
MBBMap.clear();
F = 0;
return false; // We never modify the LLVM itself.
}
virtual const char *getPassName() const {
return "X86 Simple Instruction Selection";
}
/// visitBasicBlock - This method is called when we are visiting a new basic
/// block. This simply creates a new MachineBasicBlock to emit code into
/// and adds it to the current MachineFunction. Subsequent visit* for
/// instructions will be invoked for all instructions in the basic block.
///
void visitBasicBlock(BasicBlock &LLVM_BB) {
BB = MBBMap[&LLVM_BB];
}
/// LoadArgumentsToVirtualRegs - Load all of the arguments to this function
/// from the stack into virtual registers.
///
void LoadArgumentsToVirtualRegs(Function &F);
/// SelectPHINodes - Insert machine code to generate phis. This is tricky
/// because we have to generate our sources into the source basic blocks,
/// not the current one.
///
void SelectPHINodes();
// Visitation methods for various instructions. These methods simply emit
// fixed X86 code for each instruction.
//
// Control flow operators
void visitReturnInst(ReturnInst &RI);
void visitBranchInst(BranchInst &BI);
struct ValueRecord {
unsigned Reg;
const Type *Ty;
ValueRecord(unsigned R, const Type *T) : Reg(R), Ty(T) {}
};
void doCall(const ValueRecord &Ret, MachineInstr *CallMI,
const std::vector<ValueRecord> &Args);
void visitCallInst(CallInst &I);
// Arithmetic operators
void visitSimpleBinary(BinaryOperator &B, unsigned OpcodeClass);
void visitAdd(BinaryOperator &B) { visitSimpleBinary(B, 0); }
void visitSub(BinaryOperator &B) { visitSimpleBinary(B, 1); }
void doMultiply(MachineBasicBlock *MBB, MachineBasicBlock::iterator &MBBI,
unsigned DestReg, const Type *DestTy,
unsigned Op0Reg, unsigned Op1Reg);
void visitMul(BinaryOperator &B);
void visitDiv(BinaryOperator &B) { visitDivRem(B); }
void visitRem(BinaryOperator &B) { visitDivRem(B); }
void visitDivRem(BinaryOperator &B);
// Bitwise operators
void visitAnd(BinaryOperator &B) { visitSimpleBinary(B, 2); }
void visitOr (BinaryOperator &B) { visitSimpleBinary(B, 3); }
void visitXor(BinaryOperator &B) { visitSimpleBinary(B, 4); }
// Comparison operators...
void visitSetCondInst(SetCondInst &I);
bool EmitComparisonGetSignedness(unsigned OpNum, Value *Op0, Value *Op1);
// Memory Instructions
MachineInstr *doFPLoad(MachineBasicBlock *MBB,
MachineBasicBlock::iterator &MBBI,
const Type *Ty, unsigned DestReg);
void visitLoadInst(LoadInst &I);
void doFPStore(const Type *Ty, unsigned DestAddrReg, unsigned SrcReg);
void visitStoreInst(StoreInst &I);
void visitGetElementPtrInst(GetElementPtrInst &I);
void visitAllocaInst(AllocaInst &I);
void visitMallocInst(MallocInst &I);
void visitFreeInst(FreeInst &I);
// Other operators
void visitShiftInst(ShiftInst &I);
void visitPHINode(PHINode &I) {} // PHI nodes handled by second pass
void visitCastInst(CastInst &I);
void visitInstruction(Instruction &I) {
std::cerr << "Cannot instruction select: " << I;
abort();
}
/// promote32 - Make a value 32-bits wide, and put it somewhere.
///
void promote32(unsigned targetReg, const ValueRecord &VR);
/// EmitByteSwap - Byteswap SrcReg into DestReg.
///
void EmitByteSwap(unsigned DestReg, unsigned SrcReg, unsigned Class);
/// emitGEPOperation - Common code shared between visitGetElementPtrInst and
/// constant expression GEP support.
///
void emitGEPOperation(MachineBasicBlock *BB, MachineBasicBlock::iterator&IP,
Value *Src, User::op_iterator IdxBegin,
User::op_iterator IdxEnd, unsigned TargetReg);
/// copyConstantToRegister - Output the instructions required to put the
/// specified constant into the specified register.
///
void copyConstantToRegister(MachineBasicBlock *MBB,
MachineBasicBlock::iterator &MBBI,
Constant *C, unsigned Reg);
/// makeAnotherReg - This method returns the next register number we haven't
/// yet used.
///
/// Long values are handled somewhat specially. They are always allocated
/// as pairs of 32 bit integer values. The register number returned is the
/// lower 32 bits of the long value, and the regNum+1 is the upper 32 bits
/// of the long value.
///
unsigned makeAnotherReg(const Type *Ty) {
if (Ty == Type::LongTy || Ty == Type::ULongTy) {
const TargetRegisterClass *RC =
TM.getRegisterInfo()->getRegClassForType(Type::IntTy);
// Create the lower part
F->getSSARegMap()->createVirtualRegister(RC);
// Create the upper part.
return F->getSSARegMap()->createVirtualRegister(RC)-1;
}
// Add the mapping of regnumber => reg class to MachineFunction
const TargetRegisterClass *RC =
TM.getRegisterInfo()->getRegClassForType(Ty);
return F->getSSARegMap()->createVirtualRegister(RC);
}
/// getReg - This method turns an LLVM value into a register number. This
/// is guaranteed to produce the same register number for a particular value
/// every time it is queried.
///
unsigned getReg(Value &V) { return getReg(&V); } // Allow references
unsigned getReg(Value *V) {
// Just append to the end of the current bb.
MachineBasicBlock::iterator It = BB->end();
return getReg(V, BB, It);
}
unsigned getReg(Value *V, MachineBasicBlock *MBB,
MachineBasicBlock::iterator &IPt) {
unsigned &Reg = RegMap[V];
if (Reg == 0) {
Reg = makeAnotherReg(V->getType());
RegMap[V] = Reg;
}
// If this operand is a constant, emit the code to copy the constant into
// the register here...
//
if (Constant *C = dyn_cast<Constant>(V)) {
copyConstantToRegister(MBB, IPt, C, Reg);
RegMap.erase(V); // Assign a new name to this constant if ref'd again
} else if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
// Move the address of the global into the register
BMI(MBB, IPt, X86::MOVir32, 1, Reg).addGlobalAddress(GV);
RegMap.erase(V); // Assign a new name to this address if ref'd again
}
return Reg;
}
};
}
/// TypeClass - Used by the X86 backend to group LLVM types by their basic X86
/// Representation.
///
enum TypeClass {
cByte, cShort, cInt, cFP, cLong
};
/// getClass - Turn a primitive type into a "class" number which is based on the
/// size of the type, and whether or not it is floating point.
///
static inline TypeClass getClass(const Type *Ty) {
switch (Ty->getPrimitiveID()) {
case Type::SByteTyID:
case Type::UByteTyID: return cByte; // Byte operands are class #0
case Type::ShortTyID:
case Type::UShortTyID: return cShort; // Short operands are class #1
case Type::IntTyID:
case Type::UIntTyID:
case Type::PointerTyID: return cInt; // Int's and pointers are class #2
case Type::FloatTyID:
case Type::DoubleTyID: return cFP; // Floating Point is #3
case Type::LongTyID:
case Type::ULongTyID: return cLong; // Longs are class #4
default:
assert(0 && "Invalid type to getClass!");
return cByte; // not reached
}
}
// getClassB - Just like getClass, but treat boolean values as bytes.
static inline TypeClass getClassB(const Type *Ty) {
if (Ty == Type::BoolTy) return cByte;
return getClass(Ty);
}
/// copyConstantToRegister - Output the instructions required to put the
/// specified constant into the specified register.
///
void ISel::copyConstantToRegister(MachineBasicBlock *MBB,
MachineBasicBlock::iterator &IP,
Constant *C, unsigned R) {
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
if (CE->getOpcode() == Instruction::GetElementPtr) {
emitGEPOperation(MBB, IP, CE->getOperand(0),
CE->op_begin()+1, CE->op_end(), R);
return;
}
std::cerr << "Offending expr: " << C << "\n";
assert(0 && "Constant expressions not yet handled!\n");
}
if (C->getType()->isIntegral()) {
unsigned Class = getClassB(C->getType());
if (Class == cLong) {
// Copy the value into the register pair.
uint64_t Val;
if (C->getType()->isSigned())
Val = cast<ConstantSInt>(C)->getValue();
else
Val = cast<ConstantUInt>(C)->getValue();
BMI(MBB, IP, X86::MOVir32, 1, R).addZImm(Val & 0xFFFFFFFF);
BMI(MBB, IP, X86::MOVir32, 1, R+1).addZImm(Val >> 32);
return;
}
assert(Class <= cInt && "Type not handled yet!");
static const unsigned IntegralOpcodeTab[] = {
X86::MOVir8, X86::MOVir16, X86::MOVir32
};
if (C->getType() == Type::BoolTy) {
BMI(MBB, IP, X86::MOVir8, 1, R).addZImm(C == ConstantBool::True);
} else if (C->getType()->isSigned()) {
ConstantSInt *CSI = cast<ConstantSInt>(C);
BMI(MBB, IP, IntegralOpcodeTab[Class], 1, R).addZImm(CSI->getValue());
} else {
ConstantUInt *CUI = cast<ConstantUInt>(C);
BMI(MBB, IP, IntegralOpcodeTab[Class], 1, R).addZImm(CUI->getValue());
}
} else if (ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
double Value = CFP->getValue();
if (Value == +0.0)
BMI(MBB, IP, X86::FLD0, 0, R);
else if (Value == +1.0)
BMI(MBB, IP, X86::FLD1, 0, R);
else {
// Otherwise we need to spill the constant to memory...
MachineConstantPool *CP = F->getConstantPool();
unsigned CPI = CP->getConstantPoolIndex(CFP);
addConstantPoolReference(doFPLoad(MBB, IP, CFP->getType(), R), CPI);
}
} else if (isa<ConstantPointerNull>(C)) {
// Copy zero (null pointer) to the register.
BMI(MBB, IP, X86::MOVir32, 1, R).addZImm(0);
} else if (ConstantPointerRef *CPR = dyn_cast<ConstantPointerRef>(C)) {
unsigned SrcReg = getReg(CPR->getValue(), MBB, IP);
BMI(MBB, IP, X86::MOVrr32, 1, R).addReg(SrcReg);
} else {
std::cerr << "Offending constant: " << C << "\n";
assert(0 && "Type not handled yet!");
}
}
/// LoadArgumentsToVirtualRegs - Load all of the arguments to this function from
/// the stack into virtual registers.
///
void ISel::LoadArgumentsToVirtualRegs(Function &Fn) {
// Emit instructions to load the arguments... On entry to a function on the
// X86, the stack frame looks like this:
//
// [ESP] -- return address
// [ESP + 4] -- first argument (leftmost lexically)
// [ESP + 8] -- second argument, if first argument is four bytes in size
// ...
//
unsigned ArgOffset = 0; // Frame mechanisms handle retaddr slot
MachineFrameInfo *MFI = F->getFrameInfo();
for (Function::aiterator I = Fn.abegin(), E = Fn.aend(); I != E; ++I) {
unsigned Reg = getReg(*I);
int FI; // Frame object index
switch (getClassB(I->getType())) {
case cByte:
FI = MFI->CreateFixedObject(1, ArgOffset);
addFrameReference(BuildMI(BB, X86::MOVmr8, 4, Reg), FI);
break;
case cShort:
FI = MFI->CreateFixedObject(2, ArgOffset);
addFrameReference(BuildMI(BB, X86::MOVmr16, 4, Reg), FI);
break;
case cInt:
FI = MFI->CreateFixedObject(4, ArgOffset);
addFrameReference(BuildMI(BB, X86::MOVmr32, 4, Reg), FI);
break;
case cLong:
FI = MFI->CreateFixedObject(8, ArgOffset);
addFrameReference(BuildMI(BB, X86::MOVmr32, 4, Reg), FI);
addFrameReference(BuildMI(BB, X86::MOVmr32, 4, Reg+1), FI, 4);
ArgOffset += 4; // longs require 4 additional bytes
break;
case cFP:
unsigned Opcode;
if (I->getType() == Type::FloatTy) {
Opcode = X86::FLDr32;
FI = MFI->CreateFixedObject(4, ArgOffset);
} else {
Opcode = X86::FLDr64;
FI = MFI->CreateFixedObject(8, ArgOffset);
ArgOffset += 4; // doubles require 4 additional bytes
}
addFrameReference(BuildMI(BB, Opcode, 4, Reg), FI);
break;
default:
assert(0 && "Unhandled argument type!");
}
ArgOffset += 4; // Each argument takes at least 4 bytes on the stack...
}
}
/// SelectPHINodes - Insert machine code to generate phis. This is tricky
/// because we have to generate our sources into the source basic blocks, not
/// the current one.
///
void ISel::SelectPHINodes() {
const TargetInstrInfo &TII = TM.getInstrInfo();
const Function &LF = *F->getFunction(); // The LLVM function...
for (Function::const_iterator I = LF.begin(), E = LF.end(); I != E; ++I) {
const BasicBlock *BB = I;
MachineBasicBlock *MBB = MBBMap[I];
// Loop over all of the PHI nodes in the LLVM basic block...
unsigned NumPHIs = 0;
for (BasicBlock::const_iterator I = BB->begin();
PHINode *PN = (PHINode*)dyn_cast<PHINode>(&*I); ++I) {
// Create a new machine instr PHI node, and insert it.
unsigned PHIReg = getReg(*PN);
MachineInstr *PhiMI = BuildMI(X86::PHI, PN->getNumOperands(), PHIReg);
MBB->insert(MBB->begin()+NumPHIs++, PhiMI);
MachineInstr *LongPhiMI = 0;
if (PN->getType() == Type::LongTy || PN->getType() == Type::ULongTy) {
LongPhiMI = BuildMI(X86::PHI, PN->getNumOperands(), PHIReg+1);
MBB->insert(MBB->begin()+NumPHIs++, LongPhiMI);
}
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
MachineBasicBlock *PredMBB = MBBMap[PN->getIncomingBlock(i)];
// Get the incoming value into a virtual register. If it is not already
// available in a virtual register, insert the computation code into
// PredMBB
//
MachineBasicBlock::iterator PI = PredMBB->end();
while (PI != PredMBB->begin() &&
TII.isTerminatorInstr((*(PI-1))->getOpcode()))
--PI;
unsigned ValReg = getReg(PN->getIncomingValue(i), PredMBB, PI);
PhiMI->addRegOperand(ValReg);
PhiMI->addMachineBasicBlockOperand(PredMBB);
if (LongPhiMI) {
LongPhiMI->addRegOperand(ValReg+1);
LongPhiMI->addMachineBasicBlockOperand(PredMBB);
}
}
}
}
}
// canFoldSetCCIntoBranch - Return the setcc instruction if we can fold it into
// the conditional branch instruction which is the only user of the cc
// instruction. This is the case if the conditional branch is the only user of
// the setcc, and if the setcc is in the same basic block as the conditional
// branch. We also don't handle long arguments below, so we reject them here as
// well.
//
static SetCondInst *canFoldSetCCIntoBranch(Value *V) {
if (SetCondInst *SCI = dyn_cast<SetCondInst>(V))
if (SCI->use_size() == 1 && isa<BranchInst>(SCI->use_back()) &&
SCI->getParent() == cast<BranchInst>(SCI->use_back())->getParent()) {
const Type *Ty = SCI->getOperand(0)->getType();
if (Ty != Type::LongTy && Ty != Type::ULongTy)
return SCI;
}
return 0;
}
// Return a fixed numbering for setcc instructions which does not depend on the
// order of the opcodes.
//
static unsigned getSetCCNumber(unsigned Opcode) {
switch(Opcode) {
default: assert(0 && "Unknown setcc instruction!");
case Instruction::SetEQ: return 0;
case Instruction::SetNE: return 1;
case Instruction::SetLT: return 2;
case Instruction::SetGE: return 3;
case Instruction::SetGT: return 4;
case Instruction::SetLE: return 5;
}
}
// LLVM -> X86 signed X86 unsigned
// ----- ---------- ------------
// seteq -> sete sete
// setne -> setne setne
// setlt -> setl setb
// setge -> setge setae
// setgt -> setg seta
// setle -> setle setbe
static const unsigned SetCCOpcodeTab[2][6] = {
{X86::SETEr, X86::SETNEr, X86::SETBr, X86::SETAEr, X86::SETAr, X86::SETBEr},
{X86::SETEr, X86::SETNEr, X86::SETLr, X86::SETGEr, X86::SETGr, X86::SETLEr},
};
bool ISel::EmitComparisonGetSignedness(unsigned OpNum, Value *Op0, Value *Op1) {
// The arguments are already supposed to be of the same type.
const Type *CompTy = Op0->getType();
bool isSigned = CompTy->isSigned();
unsigned reg1 = getReg(Op0);
unsigned reg2 = getReg(Op1);
unsigned Class = getClassB(CompTy);
switch (Class) {
default: assert(0 && "Unknown type class!");
// Emit: cmp <var1>, <var2> (do the comparison). We can
// compare 8-bit with 8-bit, 16-bit with 16-bit, 32-bit with
// 32-bit.
case cByte:
BuildMI(BB, X86::CMPrr8, 2).addReg(reg1).addReg(reg2);
break;
case cShort:
BuildMI(BB, X86::CMPrr16, 2).addReg(reg1).addReg(reg2);
break;
case cInt:
BuildMI(BB, X86::CMPrr32, 2).addReg(reg1).addReg(reg2);
break;
case cFP:
BuildMI(BB, X86::FpUCOM, 2).addReg(reg1).addReg(reg2);
BuildMI(BB, X86::FNSTSWr8, 0);
BuildMI(BB, X86::SAHF, 1);
isSigned = false; // Compare with unsigned operators
break;
case cLong:
if (OpNum < 2) { // seteq, setne
unsigned LoTmp = makeAnotherReg(Type::IntTy);
unsigned HiTmp = makeAnotherReg(Type::IntTy);
unsigned FinalTmp = makeAnotherReg(Type::IntTy);
BuildMI(BB, X86::XORrr32, 2, LoTmp).addReg(reg1).addReg(reg2);
BuildMI(BB, X86::XORrr32, 2, HiTmp).addReg(reg1+1).addReg(reg2+1);
BuildMI(BB, X86::ORrr32, 2, FinalTmp).addReg(LoTmp).addReg(HiTmp);
break; // Allow the sete or setne to be generated from flags set by OR
} else {
// Emit a sequence of code which compares the high and low parts once
// each, then uses a conditional move to handle the overflow case. For
// example, a setlt for long would generate code like this:
//
// AL = lo(op1) < lo(op2) // Signedness depends on operands
// BL = hi(op1) < hi(op2) // Always unsigned comparison
// dest = hi(op1) == hi(op2) ? AL : BL;
//
// FIXME: This would be much better if we had hierarchical register
// classes! Until then, hardcode registers so that we can deal with their
// aliases (because we don't have conditional byte moves).
//
BuildMI(BB, X86::CMPrr32, 2).addReg(reg1).addReg(reg2);
BuildMI(BB, SetCCOpcodeTab[0][OpNum], 0, X86::AL);
BuildMI(BB, X86::CMPrr32, 2).addReg(reg1+1).addReg(reg2+1);
BuildMI(BB, SetCCOpcodeTab[isSigned][OpNum], 0, X86::BL);
BuildMI(BB, X86::CMOVErr16, 2, X86::BX).addReg(X86::BX).addReg(X86::AX);
// NOTE: visitSetCondInst knows that the value is dumped into the BL
// register at this point for long values...
return isSigned;
}
}
return isSigned;
}
/// SetCC instructions - Here we just emit boilerplate code to set a byte-sized
/// register, then move it to wherever the result should be.
///
void ISel::visitSetCondInst(SetCondInst &I) {
if (canFoldSetCCIntoBranch(&I)) return; // Fold this into a branch...
unsigned OpNum = getSetCCNumber(I.getOpcode());
unsigned DestReg = getReg(I);
bool isSigned = EmitComparisonGetSignedness(OpNum, I.getOperand(0),
I.getOperand(1));
if (getClassB(I.getOperand(0)->getType()) != cLong || OpNum < 2) {
// Handle normal comparisons with a setcc instruction...
BuildMI(BB, SetCCOpcodeTab[isSigned][OpNum], 0, DestReg);
} else {
// Handle long comparisons by copying the value which is already in BL into
// the register we want...
BuildMI(BB, X86::MOVrr8, 1, DestReg).addReg(X86::BL);
}
}
/// promote32 - Emit instructions to turn a narrow operand into a 32-bit-wide
/// operand, in the specified target register.
void ISel::promote32(unsigned targetReg, const ValueRecord &VR) {
bool isUnsigned = VR.Ty->isUnsigned();
switch (getClassB(VR.Ty)) {
case cByte:
// Extend value into target register (8->32)
if (isUnsigned)
BuildMI(BB, X86::MOVZXr32r8, 1, targetReg).addReg(VR.Reg);
else
BuildMI(BB, X86::MOVSXr32r8, 1, targetReg).addReg(VR.Reg);
break;
case cShort:
// Extend value into target register (16->32)
if (isUnsigned)
BuildMI(BB, X86::MOVZXr32r16, 1, targetReg).addReg(VR.Reg);
else
BuildMI(BB, X86::MOVSXr32r16, 1, targetReg).addReg(VR.Reg);
break;
case cInt:
// Move value into target register (32->32)
BuildMI(BB, X86::MOVrr32, 1, targetReg).addReg(VR.Reg);
break;
default:
assert(0 && "Unpromotable operand class in promote32");
}
}
/// 'ret' instruction - Here we are interested in meeting the x86 ABI. As such,
/// we have the following possibilities:
///
/// ret void: No return value, simply emit a 'ret' instruction
/// ret sbyte, ubyte : Extend value into EAX and return
/// ret short, ushort: Extend value into EAX and return
/// ret int, uint : Move value into EAX and return
/// ret pointer : Move value into EAX and return
/// ret long, ulong : Move value into EAX/EDX and return
/// ret float/double : Top of FP stack
///
void ISel::visitReturnInst(ReturnInst &I) {
if (I.getNumOperands() == 0) {
BuildMI(BB, X86::RET, 0); // Just emit a 'ret' instruction
return;
}
Value *RetVal = I.getOperand(0);
unsigned RetReg = getReg(RetVal);
switch (getClassB(RetVal->getType())) {
case cByte: // integral return values: extend or move into EAX and return
case cShort:
case cInt:
promote32(X86::EAX, ValueRecord(RetReg, RetVal->getType()));
break;
case cFP: // Floats & Doubles: Return in ST(0)
BuildMI(BB, X86::FpSETRESULT, 1).addReg(RetReg);
break;
case cLong:
BuildMI(BB, X86::MOVrr32, 1, X86::EAX).addReg(RetReg);
BuildMI(BB, X86::MOVrr32, 1, X86::EDX).addReg(RetReg+1);
break;
default:
visitInstruction(I);
}
// Emit a 'ret' instruction
BuildMI(BB, X86::RET, 0);
}
// getBlockAfter - Return the basic block which occurs lexically after the
// specified one.
static inline BasicBlock *getBlockAfter(BasicBlock *BB) {
Function::iterator I = BB; ++I; // Get iterator to next block
return I != BB->getParent()->end() ? &*I : 0;
}
/// visitBranchInst - Handle conditional and unconditional branches here. Note
/// that since code layout is frozen at this point, that if we are trying to
/// jump to a block that is the immediate successor of the current block, we can
/// just make a fall-through (but we don't currently).
///
void ISel::visitBranchInst(BranchInst &BI) {
BasicBlock *NextBB = getBlockAfter(BI.getParent()); // BB after current one
if (!BI.isConditional()) { // Unconditional branch?
if (BI.getSuccessor(0) != NextBB)
BuildMI(BB, X86::JMP, 1).addPCDisp(BI.getSuccessor(0));
return;
}
// See if we can fold the setcc into the branch itself...
SetCondInst *SCI = canFoldSetCCIntoBranch(BI.getCondition());
if (SCI == 0) {
// Nope, cannot fold setcc into this branch. Emit a branch on a condition
// computed some other way...
unsigned condReg = getReg(BI.getCondition());
BuildMI(BB, X86::CMPri8, 2).addReg(condReg).addZImm(0);
if (BI.getSuccessor(1) == NextBB) {
if (BI.getSuccessor(0) != NextBB)
BuildMI(BB, X86::JNE, 1).addPCDisp(BI.getSuccessor(0));
} else {
BuildMI(BB, X86::JE, 1).addPCDisp(BI.getSuccessor(1));
if (BI.getSuccessor(0) != NextBB)
BuildMI(BB, X86::JMP, 1).addPCDisp(BI.getSuccessor(0));
}
return;
}
unsigned OpNum = getSetCCNumber(SCI->getOpcode());
bool isSigned = EmitComparisonGetSignedness(OpNum, SCI->getOperand(0),
SCI->getOperand(1));
// LLVM -> X86 signed X86 unsigned
// ----- ---------- ------------
// seteq -> je je
// setne -> jne jne
// setlt -> jl jb
// setge -> jge jae
// setgt -> jg ja
// setle -> jle jbe
static const unsigned OpcodeTab[2][6] = {
{ X86::JE, X86::JNE, X86::JB, X86::JAE, X86::JA, X86::JBE },
{ X86::JE, X86::JNE, X86::JL, X86::JGE, X86::JG, X86::JLE },
};
if (BI.getSuccessor(0) != NextBB) {
BuildMI(BB, OpcodeTab[isSigned][OpNum], 1).addPCDisp(BI.getSuccessor(0));
if (BI.getSuccessor(1) != NextBB)
BuildMI(BB, X86::JMP, 1).addPCDisp(BI.getSuccessor(1));
} else {
// Change to the inverse condition...
if (BI.getSuccessor(1) != NextBB) {
OpNum ^= 1;
BuildMI(BB, OpcodeTab[isSigned][OpNum], 1).addPCDisp(BI.getSuccessor(1));
}
}
}
/// doCall - This emits an abstract call instruction, setting up the arguments
/// and the return value as appropriate. For the actual function call itself,
/// it inserts the specified CallMI instruction into the stream.
///
void ISel::doCall(const ValueRecord &Ret, MachineInstr *CallMI,
const std::vector<ValueRecord> &Args) {
// Count how many bytes are to be pushed on the stack...
unsigned NumBytes = 0;
if (!Args.empty()) {
for (unsigned i = 0, e = Args.size(); i != e; ++i)
switch (getClassB(Args[i].Ty)) {
case cByte: case cShort: case cInt:
NumBytes += 4; break;
case cLong:
NumBytes += 8; break;
case cFP:
NumBytes += Args[i].Ty == Type::FloatTy ? 4 : 8;
break;
default: assert(0 && "Unknown class!");
}
// Adjust the stack pointer for the new arguments...
BuildMI(BB, X86::ADJCALLSTACKDOWN, 1).addZImm(NumBytes);
// Arguments go on the stack in reverse order, as specified by the ABI.
unsigned ArgOffset = 0;
for (unsigned i = 0, e = Args.size(); i != e; ++i) {
unsigned ArgReg = Args[i].Reg;
switch (getClassB(Args[i].Ty)) {
case cByte:
case cShort: {
// Promote arg to 32 bits wide into a temporary register...
unsigned R = makeAnotherReg(Type::UIntTy);
promote32(R, Args[i]);
addRegOffset(BuildMI(BB, X86::MOVrm32, 5),
X86::ESP, ArgOffset).addReg(R);
break;
}
case cInt:
addRegOffset(BuildMI(BB, X86::MOVrm32, 5),
X86::ESP, ArgOffset).addReg(ArgReg);
break;
case cLong:
addRegOffset(BuildMI(BB, X86::MOVrm32, 5),
X86::ESP, ArgOffset).addReg(ArgReg);
addRegOffset(BuildMI(BB, X86::MOVrm32, 5),
X86::ESP, ArgOffset+4).addReg(ArgReg+1);
ArgOffset += 4; // 8 byte entry, not 4.
break;
case cFP:
if (Args[i].Ty == Type::FloatTy) {
addRegOffset(BuildMI(BB, X86::FSTr32, 5),
X86::ESP, ArgOffset).addReg(ArgReg);
} else {
assert(Args[i].Ty == Type::DoubleTy && "Unknown FP type!");
addRegOffset(BuildMI(BB, X86::FSTr64, 5),
X86::ESP, ArgOffset).addReg(ArgReg);
ArgOffset += 4; // 8 byte entry, not 4.
}
break;
default: assert(0 && "Unknown class!");
}
ArgOffset += 4;
}
} else {
BuildMI(BB, X86::ADJCALLSTACKDOWN, 1).addZImm(0);
}
BB->push_back(CallMI);
BuildMI(BB, X86::ADJCALLSTACKUP, 1).addZImm(NumBytes);
// If there is a return value, scavenge the result from the location the call
// leaves it in...
//
if (Ret.Ty != Type::VoidTy) {
unsigned DestClass = getClassB(Ret.Ty);
switch (DestClass) {
case cByte:
case cShort:
case cInt: {
// Integral results are in %eax, or the appropriate portion
// thereof.
static const unsigned regRegMove[] = {
X86::MOVrr8, X86::MOVrr16, X86::MOVrr32
};
static const unsigned AReg[] = { X86::AL, X86::AX, X86::EAX };
BuildMI(BB, regRegMove[DestClass], 1, Ret.Reg).addReg(AReg[DestClass]);
break;
}
case cFP: // Floating-point return values live in %ST(0)
BuildMI(BB, X86::FpGETRESULT, 1, Ret.Reg);
break;
case cLong: // Long values are left in EDX:EAX
BuildMI(BB, X86::MOVrr32, 1, Ret.Reg).addReg(X86::EAX);
BuildMI(BB, X86::MOVrr32, 1, Ret.Reg+1).addReg(X86::EDX);
break;
default: assert(0 && "Unknown class!");
}
}
}
/// visitCallInst - Push args on stack and do a procedure call instruction.
void ISel::visitCallInst(CallInst &CI) {
MachineInstr *TheCall;
if (Function *F = CI.getCalledFunction()) {
// Emit a CALL instruction with PC-relative displacement.
TheCall = BuildMI(X86::CALLpcrel32, 1).addGlobalAddress(F, true);
} else { // Emit an indirect call...
unsigned Reg = getReg(CI.getCalledValue());
TheCall = BuildMI(X86::CALLr32, 1).addReg(Reg);
}
std::vector<ValueRecord> Args;
for (unsigned i = 1, e = CI.getNumOperands(); i != e; ++i)
Args.push_back(ValueRecord(getReg(CI.getOperand(i)),
CI.getOperand(i)->getType()));
unsigned DestReg = CI.getType() != Type::VoidTy ? getReg(CI) : 0;
doCall(ValueRecord(DestReg, CI.getType()), TheCall, Args);
}
/// visitSimpleBinary - Implement simple binary operators for integral types...
/// OperatorClass is one of: 0 for Add, 1 for Sub, 2 for And, 3 for Or,
/// 4 for Xor.
///
void ISel::visitSimpleBinary(BinaryOperator &B, unsigned OperatorClass) {
unsigned Class = getClassB(B.getType());
static const unsigned OpcodeTab[][4] = {
// Arithmetic operators
{ X86::ADDrr8, X86::ADDrr16, X86::ADDrr32, X86::FpADD }, // ADD
{ X86::SUBrr8, X86::SUBrr16, X86::SUBrr32, X86::FpSUB }, // SUB
// Bitwise operators
{ X86::ANDrr8, X86::ANDrr16, X86::ANDrr32, 0 }, // AND
{ X86:: ORrr8, X86:: ORrr16, X86:: ORrr32, 0 }, // OR
{ X86::XORrr8, X86::XORrr16, X86::XORrr32, 0 }, // XOR
};
bool isLong = false;
if (Class == cLong) {
isLong = true;
Class = cInt; // Bottom 32 bits are handled just like ints
}
unsigned Opcode = OpcodeTab[OperatorClass][Class];
assert(Opcode && "Floating point arguments to logical inst?");
unsigned Op0r = getReg(B.getOperand(0));
unsigned Op1r = getReg(B.getOperand(1));
unsigned DestReg = getReg(B);
BuildMI(BB, Opcode, 2, DestReg).addReg(Op0r).addReg(Op1r);
if (isLong) { // Handle the upper 32 bits of long values...
static const unsigned TopTab[] = {
X86::ADCrr32, X86::SBBrr32, X86::ANDrr32, X86::ORrr32, X86::XORrr32
};
BuildMI(BB, TopTab[OperatorClass], 2,
DestReg+1).addReg(Op0r+1).addReg(Op1r+1);
}
}
/// doMultiply - Emit appropriate instructions to multiply together the
/// registers op0Reg and op1Reg, and put the result in DestReg. The type of the
/// result should be given as DestTy.
///
/// FIXME: doMultiply should use one of the two address IMUL instructions!
///
void ISel::doMultiply(MachineBasicBlock *MBB, MachineBasicBlock::iterator &MBBI,
unsigned DestReg, const Type *DestTy,
unsigned op0Reg, unsigned op1Reg) {
unsigned Class = getClass(DestTy);
switch (Class) {
case cFP: // Floating point multiply
BMI(BB, MBBI, X86::FpMUL, 2, DestReg).addReg(op0Reg).addReg(op1Reg);
return;
default:
case cLong: assert(0 && "doMultiply cannot operate on LONG values!");
case cByte:
case cShort:
case cInt: // Small integerals, handled below...
break;
}
static const unsigned Regs[] ={ X86::AL , X86::AX , X86::EAX };
static const unsigned MulOpcode[]={ X86::MULr8 , X86::MULr16 , X86::MULr32 };
static const unsigned MovOpcode[]={ X86::MOVrr8, X86::MOVrr16, X86::MOVrr32 };
unsigned Reg = Regs[Class];
// Emit a MOV to put the first operand into the appropriately-sized
// subreg of EAX.
BMI(MBB, MBBI, MovOpcode[Class], 1, Reg).addReg(op0Reg);
// Emit the appropriate multiply instruction.
BMI(MBB, MBBI, MulOpcode[Class], 1).addReg(op1Reg);
// Emit another MOV to put the result into the destination register.
BMI(MBB, MBBI, MovOpcode[Class], 1, DestReg).addReg(Reg);
}
/// visitMul - Multiplies are not simple binary operators because they must deal
/// with the EAX register explicitly.
///
void ISel::visitMul(BinaryOperator &I) {
unsigned Op0Reg = getReg(I.getOperand(0));
unsigned Op1Reg = getReg(I.getOperand(1));
unsigned DestReg = getReg(I);
// Simple scalar multiply?
if (I.getType() != Type::LongTy && I.getType() != Type::ULongTy) {
MachineBasicBlock::iterator MBBI = BB->end();
doMultiply(BB, MBBI, DestReg, I.getType(), Op0Reg, Op1Reg);
} else {
// Long value. We have to do things the hard way...
// Multiply the two low parts... capturing carry into EDX
BuildMI(BB, X86::MOVrr32, 1, X86::EAX).addReg(Op0Reg);
BuildMI(BB, X86::MULr32, 1).addReg(Op1Reg); // AL*BL
unsigned OverflowReg = makeAnotherReg(Type::UIntTy);
BuildMI(BB, X86::MOVrr32, 1, DestReg).addReg(X86::EAX); // AL*BL
BuildMI(BB, X86::MOVrr32, 1, OverflowReg).addReg(X86::EDX); // AL*BL >> 32
MachineBasicBlock::iterator MBBI = BB->end();
unsigned AHBLReg = makeAnotherReg(Type::UIntTy);
doMultiply(BB, MBBI, AHBLReg, Type::UIntTy, Op0Reg+1, Op1Reg); // AH*BL
unsigned AHBLplusOverflowReg = makeAnotherReg(Type::UIntTy);
BuildMI(BB, X86::ADDrr32, 2, // AH*BL+(AL*BL >> 32)
AHBLplusOverflowReg).addReg(AHBLReg).addReg(OverflowReg);
MBBI = BB->end();
unsigned ALBHReg = makeAnotherReg(Type::UIntTy);
doMultiply(BB, MBBI, ALBHReg, Type::UIntTy, Op0Reg, Op1Reg+1); // AL*BH
BuildMI(BB, X86::ADDrr32, 2, // AL*BH + AH*BL + (AL*BL >> 32)
DestReg+1).addReg(AHBLplusOverflowReg).addReg(ALBHReg);
}
}
/// visitDivRem - Handle division and remainder instructions... these
/// instruction both require the same instructions to be generated, they just
/// select the result from a different register. Note that both of these
/// instructions work differently for signed and unsigned operands.
///
void ISel::visitDivRem(BinaryOperator &I) {
unsigned Class = getClass(I.getType());
unsigned Op0Reg = getReg(I.getOperand(0));
unsigned Op1Reg = getReg(I.getOperand(1));
unsigned ResultReg = getReg(I);
switch (Class) {
case cFP: // Floating point divide
if (I.getOpcode() == Instruction::Div)
BuildMI(BB, X86::FpDIV, 2, ResultReg).addReg(Op0Reg).addReg(Op1Reg);
else { // Floating point remainder...
MachineInstr *TheCall =
BuildMI(X86::CALLpcrel32, 1).addExternalSymbol("fmod", true);
std::vector<ValueRecord> Args;
Args.push_back(ValueRecord(Op0Reg, Type::DoubleTy));
Args.push_back(ValueRecord(Op1Reg, Type::DoubleTy));
doCall(ValueRecord(ResultReg, Type::DoubleTy), TheCall, Args);
}
return;
case cLong: {
static const char *FnName[] =
{ "__moddi3", "__divdi3", "__umoddi3", "__udivdi3" };
unsigned NameIdx = I.getType()->isUnsigned()*2;
NameIdx += I.getOpcode() == Instruction::Div;
MachineInstr *TheCall =
BuildMI(X86::CALLpcrel32, 1).addExternalSymbol(FnName[NameIdx], true);
std::vector<ValueRecord> Args;
Args.push_back(ValueRecord(Op0Reg, Type::LongTy));
Args.push_back(ValueRecord(Op1Reg, Type::LongTy));
doCall(ValueRecord(ResultReg, Type::LongTy), TheCall, Args);
return;
}
case cByte: case cShort: case cInt:
break; // Small integerals, handled below...
default: assert(0 && "Unknown class!");
}
static const unsigned Regs[] ={ X86::AL , X86::AX , X86::EAX };
static const unsigned MovOpcode[]={ X86::MOVrr8, X86::MOVrr16, X86::MOVrr32 };
static const unsigned ExtOpcode[]={ X86::CBW , X86::CWD , X86::CDQ };
static const unsigned ClrOpcode[]={ X86::XORrr8, X86::XORrr16, X86::XORrr32 };
static const unsigned ExtRegs[] ={ X86::AH , X86::DX , X86::EDX };
static const unsigned DivOpcode[][4] = {
{ X86::DIVr8 , X86::DIVr16 , X86::DIVr32 , 0 }, // Unsigned division
{ X86::IDIVr8, X86::IDIVr16, X86::IDIVr32, 0 }, // Signed division
};
bool isSigned = I.getType()->isSigned();
unsigned Reg = Regs[Class];
unsigned ExtReg = ExtRegs[Class];
// Put the first operand into one of the A registers...
BuildMI(BB, MovOpcode[Class], 1, Reg).addReg(Op0Reg);
if (isSigned) {
// Emit a sign extension instruction...
BuildMI(BB, ExtOpcode[Class], 0);
} else {
// If unsigned, emit a zeroing instruction... (reg = xor reg, reg)
BuildMI(BB, ClrOpcode[Class], 2, ExtReg).addReg(ExtReg).addReg(ExtReg);
}
// Emit the appropriate divide or remainder instruction...
BuildMI(BB, DivOpcode[isSigned][Class], 1).addReg(Op1Reg);
// Figure out which register we want to pick the result out of...
unsigned DestReg = (I.getOpcode() == Instruction::Div) ? Reg : ExtReg;
// Put the result into the destination register...
BuildMI(BB, MovOpcode[Class], 1, ResultReg).addReg(DestReg);
}
/// Shift instructions: 'shl', 'sar', 'shr' - Some special cases here
/// for constant immediate shift values, and for constant immediate
/// shift values equal to 1. Even the general case is sort of special,
/// because the shift amount has to be in CL, not just any old register.
///
void ISel::visitShiftInst(ShiftInst &I) {
unsigned SrcReg = getReg(I.getOperand(0));
unsigned DestReg = getReg(I);
bool isLeftShift = I.getOpcode() == Instruction::Shl;
bool isSigned = I.getType()->isSigned();
unsigned Class = getClass(I.getType());
static const unsigned ConstantOperand[][4] = {
{ X86::SHRir8, X86::SHRir16, X86::SHRir32, X86::SHRDir32 }, // SHR
{ X86::SARir8, X86::SARir16, X86::SARir32, X86::SHRDir32 }, // SAR
{ X86::SHLir8, X86::SHLir16, X86::SHLir32, X86::SHLDir32 }, // SHL
{ X86::SHLir8, X86::SHLir16, X86::SHLir32, X86::SHLDir32 }, // SAL = SHL
};
static const unsigned NonConstantOperand[][4] = {
{ X86::SHRrr8, X86::SHRrr16, X86::SHRrr32 }, // SHR
{ X86::SARrr8, X86::SARrr16, X86::SARrr32 }, // SAR
{ X86::SHLrr8, X86::SHLrr16, X86::SHLrr32 }, // SHL
{ X86::SHLrr8, X86::SHLrr16, X86::SHLrr32 }, // SAL = SHL
};
// Longs, as usual, are handled specially...
if (Class == cLong) {
// If we have a constant shift, we can generate much more efficient code
// than otherwise...
//
if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(I.getOperand(1))) {
unsigned Amount = CUI->getValue();
if (Amount < 32) {
const unsigned *Opc = ConstantOperand[isLeftShift*2+isSigned];
if (isLeftShift) {
BuildMI(BB, Opc[3], 3,
DestReg+1).addReg(SrcReg+1).addReg(SrcReg).addZImm(Amount);
BuildMI(BB, Opc[2], 2, DestReg).addReg(SrcReg).addZImm(Amount);
} else {
BuildMI(BB, Opc[3], 3,
DestReg).addReg(SrcReg ).addReg(SrcReg+1).addZImm(Amount);
BuildMI(BB, Opc[2], 2, DestReg+1).addReg(SrcReg+1).addZImm(Amount);
}
} else { // Shifting more than 32 bits
Amount -= 32;
if (isLeftShift) {
BuildMI(BB, X86::SHLir32, 2,DestReg+1).addReg(SrcReg).addZImm(Amount);
BuildMI(BB, X86::MOVir32, 1,DestReg ).addZImm(0);
} else {
unsigned Opcode = isSigned ? X86::SARir32 : X86::SHRir32;
BuildMI(BB, Opcode, 2, DestReg).addReg(SrcReg+1).addZImm(Amount);
BuildMI(BB, X86::MOVir32, 1, DestReg+1).addZImm(0);
}
}
} else {
visitInstruction(I); // FIXME: Implement long shift by non-constant
}
return;
}
if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(I.getOperand(1))) {
// The shift amount is constant, guaranteed to be a ubyte. Get its value.
assert(CUI->getType() == Type::UByteTy && "Shift amount not a ubyte?");
const unsigned *Opc = ConstantOperand[isLeftShift*2+isSigned];
BuildMI(BB, Opc[Class], 2, DestReg).addReg(SrcReg).addZImm(CUI->getValue());
} else { // The shift amount is non-constant.
BuildMI(BB, X86::MOVrr8, 1, X86::CL).addReg(getReg(I.getOperand(1)));
const unsigned *Opc = NonConstantOperand[isLeftShift*2+isSigned];
BuildMI(BB, Opc[Class], 1, DestReg).addReg(SrcReg);
}
}
/// doFPLoad - This method is used to load an FP value from memory using the
/// current endianness. NOTE: This method returns a partially constructed load
/// instruction which needs to have the memory source filled in still.
///
MachineInstr *ISel::doFPLoad(MachineBasicBlock *MBB,
MachineBasicBlock::iterator &MBBI,
const Type *Ty, unsigned DestReg) {
assert(Ty == Type::FloatTy || Ty == Type::DoubleTy && "Unknown FP type!");
unsigned LoadOpcode = Ty == Type::FloatTy ? X86::FLDr32 : X86::FLDr64;
if (TM.getTargetData().isLittleEndian()) // fast path...
return BMI(MBB, MBBI, LoadOpcode, 4, DestReg);
// If we are big-endian, start by creating an LEA instruction to represent the
// address of the memory location to load from...
//
unsigned SrcAddrReg = makeAnotherReg(Type::UIntTy);
MachineInstr *Result = BMI(MBB, MBBI, X86::LEAr32, 5, SrcAddrReg);
// Allocate a temporary stack slot to transform the value into...
int FrameIdx = F->getFrameInfo()->CreateStackObject(Ty, TM.getTargetData());
// Perform the bswaps 32 bits at a time...
unsigned TmpReg1 = makeAnotherReg(Type::UIntTy);
unsigned TmpReg2 = makeAnotherReg(Type::UIntTy);
addDirectMem(BMI(MBB, MBBI, X86::MOVmr32, 4, TmpReg1), SrcAddrReg);
BMI(MBB, MBBI, X86::BSWAPr32, 1, TmpReg2).addReg(TmpReg1);
unsigned Offset = (Ty == Type::DoubleTy) << 2;
addFrameReference(BMI(MBB, MBBI, X86::MOVrm32, 5),
FrameIdx, Offset).addReg(TmpReg2);
if (Ty == Type::DoubleTy) { // Swap the other 32 bits of a double value...
TmpReg1 = makeAnotherReg(Type::UIntTy);
TmpReg2 = makeAnotherReg(Type::UIntTy);
addRegOffset(BMI(MBB, MBBI, X86::MOVmr32, 4, TmpReg1), SrcAddrReg, 4);
BMI(MBB, MBBI, X86::BSWAPr32, 1, TmpReg2).addReg(TmpReg1);
unsigned Offset = (Ty == Type::DoubleTy) << 2;
addFrameReference(BMI(MBB, MBBI, X86::MOVrm32,5), FrameIdx).addReg(TmpReg2);
}
// Now we can reload the final byteswapped result into the final destination.
addFrameReference(BMI(MBB, MBBI, LoadOpcode, 4, DestReg), FrameIdx);
return Result;
}
/// EmitByteSwap - Byteswap SrcReg into DestReg.
///
void ISel::EmitByteSwap(unsigned DestReg, unsigned SrcReg, unsigned Class) {
// Emit the byte swap instruction...
switch (Class) {
case cByte:
// No byteswap neccesary for 8 bit value...
BuildMI(BB, X86::MOVrr8, 1, DestReg).addReg(SrcReg);
break;
case cInt:
// Use the 32 bit bswap instruction to do a 32 bit swap...
BuildMI(BB, X86::BSWAPr32, 1, DestReg).addReg(SrcReg);
break;
case cShort:
// For 16 bit we have to use an xchg instruction, because there is no
// 16-bit bswap. XCHG is neccesarily not in SSA form, so we force things
// into AX to do the xchg.
//
BuildMI(BB, X86::MOVrr16, 1, X86::AX).addReg(SrcReg);
BuildMI(BB, X86::XCHGrr8, 2).addReg(X86::AL, MOTy::UseAndDef)
.addReg(X86::AH, MOTy::UseAndDef);
BuildMI(BB, X86::MOVrr16, 1, DestReg).addReg(X86::AX);
break;
default: assert(0 && "Cannot byteswap this class!");
}
}
/// visitLoadInst - Implement LLVM load instructions in terms of the x86 'mov'
/// instruction. The load and store instructions are the only place where we
/// need to worry about the memory layout of the target machine.
///
void ISel::visitLoadInst(LoadInst &I) {
bool isLittleEndian = TM.getTargetData().isLittleEndian();
bool hasLongPointers = TM.getTargetData().getPointerSize() == 8;
unsigned SrcAddrReg = getReg(I.getOperand(0));
unsigned DestReg = getReg(I);
unsigned Class = getClass(I.getType());
switch (Class) {
case cFP: {
MachineBasicBlock::iterator MBBI = BB->end();
addDirectMem(doFPLoad(BB, MBBI, I.getType(), DestReg), SrcAddrReg);
return;
}
case cLong: case cInt: case cShort: case cByte:
break; // Integers of various sizes handled below
default: assert(0 && "Unknown memory class!");
}
// We need to adjust the input pointer if we are emulating a big-endian
// long-pointer target. On these systems, the pointer that we are interested
// in is in the upper part of the eight byte memory image of the pointer. It
// also happens to be byte-swapped, but this will be handled later.
//
if (!isLittleEndian && hasLongPointers && isa<PointerType>(I.getType())) {
unsigned R = makeAnotherReg(Type::UIntTy);
BuildMI(BB, X86::ADDri32, 2, R).addReg(SrcAddrReg).addZImm(4);
SrcAddrReg = R;
}
unsigned IReg = DestReg;
if (!isLittleEndian) // If big endian we need an intermediate stage
DestReg = makeAnotherReg(Class != cLong ? I.getType() : Type::UIntTy);
static const unsigned Opcode[] = {
X86::MOVmr8, X86::MOVmr16, X86::MOVmr32, 0, X86::MOVmr32
};
addDirectMem(BuildMI(BB, Opcode[Class], 4, DestReg), SrcAddrReg);
// Handle long values now...
if (Class == cLong) {
if (isLittleEndian) {
addRegOffset(BuildMI(BB, X86::MOVmr32, 4, DestReg+1), SrcAddrReg, 4);
} else {
EmitByteSwap(IReg+1, DestReg, cInt);
unsigned TempReg = makeAnotherReg(Type::IntTy);
addRegOffset(BuildMI(BB, X86::MOVmr32, 4, TempReg), SrcAddrReg, 4);
EmitByteSwap(IReg, TempReg, cInt);
}
return;
}
if (!isLittleEndian)
EmitByteSwap(IReg, DestReg, Class);
}
/// doFPStore - This method is used to store an FP value to memory using the
/// current endianness.
///
void ISel::doFPStore(const Type *Ty, unsigned DestAddrReg, unsigned SrcReg) {
assert(Ty == Type::FloatTy || Ty == Type::DoubleTy && "Unknown FP type!");
unsigned StoreOpcode = Ty == Type::FloatTy ? X86::FSTr32 : X86::FSTr64;
if (TM.getTargetData().isLittleEndian()) { // fast path...
addDirectMem(BuildMI(BB, StoreOpcode,5), DestAddrReg).addReg(SrcReg);
return;
}
// Allocate a temporary stack slot to transform the value into...
int FrameIdx = F->getFrameInfo()->CreateStackObject(Ty, TM.getTargetData());
unsigned SrcAddrReg = makeAnotherReg(Type::UIntTy);
addFrameReference(BuildMI(BB, X86::LEAr32, 5, SrcAddrReg), FrameIdx);
// Store the value into a temporary stack slot...
addDirectMem(BuildMI(BB, StoreOpcode, 5), SrcAddrReg).addReg(SrcReg);
// Perform the bswaps 32 bits at a time...
unsigned TmpReg1 = makeAnotherReg(Type::UIntTy);
unsigned TmpReg2 = makeAnotherReg(Type::UIntTy);
addDirectMem(BuildMI(BB, X86::MOVmr32, 4, TmpReg1), SrcAddrReg);
BuildMI(BB, X86::BSWAPr32, 1, TmpReg2).addReg(TmpReg1);
unsigned Offset = (Ty == Type::DoubleTy) << 2;
addRegOffset(BuildMI(BB, X86::MOVrm32, 5),
DestAddrReg, Offset).addReg(TmpReg2);
if (Ty == Type::DoubleTy) { // Swap the other 32 bits of a double value...
TmpReg1 = makeAnotherReg(Type::UIntTy);
TmpReg2 = makeAnotherReg(Type::UIntTy);
addRegOffset(BuildMI(BB, X86::MOVmr32, 4, TmpReg1), SrcAddrReg, 4);
BuildMI(BB, X86::BSWAPr32, 1, TmpReg2).addReg(TmpReg1);
unsigned Offset = (Ty == Type::DoubleTy) << 2;
addDirectMem(BuildMI(BB, X86::MOVrm32, 5), DestAddrReg).addReg(TmpReg2);
}
}
/// visitStoreInst - Implement LLVM store instructions in terms of the x86 'mov'
/// instruction.
///
void ISel::visitStoreInst(StoreInst &I) {
bool isLittleEndian = TM.getTargetData().isLittleEndian();
bool hasLongPointers = TM.getTargetData().getPointerSize() == 8;
unsigned ValReg = getReg(I.getOperand(0));
unsigned AddressReg = getReg(I.getOperand(1));
unsigned Class = getClass(I.getOperand(0)->getType());
switch (Class) {
case cLong:
if (isLittleEndian) {
addDirectMem(BuildMI(BB, X86::MOVrm32, 1+4), AddressReg).addReg(ValReg);
addRegOffset(BuildMI(BB, X86::MOVrm32, 1+4),
AddressReg, 4).addReg(ValReg+1);
} else {
unsigned T1 = makeAnotherReg(Type::IntTy);
unsigned T2 = makeAnotherReg(Type::IntTy);
EmitByteSwap(T1, ValReg , cInt);
EmitByteSwap(T2, ValReg+1, cInt);
addDirectMem(BuildMI(BB, X86::MOVrm32, 1+4), AddressReg).addReg(T2);
addRegOffset(BuildMI(BB, X86::MOVrm32, 1+4), AddressReg, 4).addReg(T1);
}
return;
case cFP:
doFPStore(I.getOperand(0)->getType(), AddressReg, ValReg);
return;
case cInt: case cShort: case cByte:
break; // Integers of various sizes handled below
default: assert(0 && "Unknown memory class!");
}
if (!isLittleEndian && hasLongPointers &&
isa<PointerType>(I.getOperand(0)->getType())) {
unsigned R = makeAnotherReg(Type::UIntTy);
BuildMI(BB, X86::ADDri32, 2, R).addReg(AddressReg).addZImm(4);
AddressReg = R;
}
if (!isLittleEndian && Class != cByte) {
unsigned R = makeAnotherReg(I.getOperand(0)->getType());
EmitByteSwap(R, ValReg, Class);
ValReg = R;
}
static const unsigned Opcode[] = { X86::MOVrm8, X86::MOVrm16, X86::MOVrm32 };
addDirectMem(BuildMI(BB, Opcode[Class], 1+4), AddressReg).addReg(ValReg);
}
/// visitCastInst - Here we have various kinds of copying with or without
/// sign extension going on.
void ISel::visitCastInst(CastInst &CI) {
const Type *DestTy = CI.getType();
Value *Src = CI.getOperand(0);
unsigned SrcReg = getReg(Src);
const Type *SrcTy = Src->getType();
unsigned SrcClass = getClassB(SrcTy);
unsigned DestReg = getReg(CI);
unsigned DestClass = getClassB(DestTy);
// Implement casts to bool by using compare on the operand followed by set if
// not zero on the result.
if (DestTy == Type::BoolTy) {
if (SrcClass == cFP || SrcClass == cLong)
visitInstruction(CI);
BuildMI(BB, X86::CMPri8, 2).addReg(SrcReg).addZImm(0);
BuildMI(BB, X86::SETNEr, 1, DestReg);
return;
}
static const unsigned RegRegMove[] = {
X86::MOVrr8, X86::MOVrr16, X86::MOVrr32, X86::FpMOV, X86::MOVrr32
};
// Implement casts between values of the same type class (as determined by
// getClass) by using a register-to-register move.
if (SrcClass == DestClass) {
if (SrcClass <= cInt || (SrcClass == cFP && SrcTy == DestTy)) {
BuildMI(BB, RegRegMove[SrcClass], 1, DestReg).addReg(SrcReg);
} else if (SrcClass == cFP) {
if (SrcTy == Type::FloatTy) { // double -> float
assert(DestTy == Type::DoubleTy && "Unknown cFP member!");
BuildMI(BB, X86::FpMOV, 1, DestReg).addReg(SrcReg);
} else { // float -> double
assert(SrcTy == Type::DoubleTy && DestTy == Type::FloatTy &&
"Unknown cFP member!");
// Truncate from double to float by storing to memory as short, then
// reading it back.
unsigned FltAlign = TM.getTargetData().getFloatAlignment();
int FrameIdx = F->getFrameInfo()->CreateStackObject(4, FltAlign);
addFrameReference(BuildMI(BB, X86::FSTr32, 5), FrameIdx).addReg(SrcReg);
addFrameReference(BuildMI(BB, X86::FLDr32, 5, DestReg), FrameIdx);
}
} else if (SrcClass == cLong) {
BuildMI(BB, X86::MOVrr32, 1, DestReg).addReg(SrcReg);
BuildMI(BB, X86::MOVrr32, 1, DestReg+1).addReg(SrcReg+1);
} else {
visitInstruction(CI);
}
return;
}
// Handle cast of SMALLER int to LARGER int using a move with sign extension
// or zero extension, depending on whether the source type was signed.
if (SrcClass <= cInt && (DestClass <= cInt || DestClass == cLong) &&
SrcClass < DestClass) {
bool isLong = DestClass == cLong;
if (isLong) DestClass = cInt;
static const unsigned Opc[][4] = {
{ X86::MOVSXr16r8, X86::MOVSXr32r8, X86::MOVSXr32r16, X86::MOVrr32 }, // s
{ X86::MOVZXr16r8, X86::MOVZXr32r8, X86::MOVZXr32r16, X86::MOVrr32 } // u
};
bool isUnsigned = SrcTy->isUnsigned();
BuildMI(BB, Opc[isUnsigned][SrcClass + DestClass - 1], 1,
DestReg).addReg(SrcReg);
if (isLong) { // Handle upper 32 bits as appropriate...
if (isUnsigned) // Zero out top bits...
BuildMI(BB, X86::MOVir32, 1, DestReg+1).addZImm(0);
else // Sign extend bottom half...
BuildMI(BB, X86::SARir32, 2, DestReg+1).addReg(DestReg).addZImm(31);
}
return;
}
// Special case long -> int ...
if (SrcClass == cLong && DestClass == cInt) {
BuildMI(BB, X86::MOVrr32, 1, DestReg).addReg(SrcReg);
return;
}
// Handle cast of LARGER int to SMALLER int using a move to EAX followed by a
// move out of AX or AL.
if ((SrcClass <= cInt || SrcClass == cLong) && DestClass <= cInt
&& SrcClass > DestClass) {
static const unsigned AReg[] = { X86::AL, X86::AX, X86::EAX, 0, X86::EAX };
BuildMI(BB, RegRegMove[SrcClass], 1, AReg[SrcClass]).addReg(SrcReg);
BuildMI(BB, RegRegMove[DestClass], 1, DestReg).addReg(AReg[DestClass]);
return;
}
// Handle casts from integer to floating point now...
if (DestClass == cFP) {
// unsigned int -> load as 64 bit int.
// unsigned long long -> more complex
if (SrcTy->isUnsigned() && SrcTy != Type::UByteTy)
visitInstruction(CI); // don't handle unsigned src yet!
// We don't have the facilities for directly loading byte sized data from
// memory. Promote it to 16 bits.
if (SrcClass == cByte) {
unsigned TmpReg = makeAnotherReg(Type::ShortTy);
BuildMI(BB, SrcTy->isSigned() ? X86::MOVSXr16r8 : X86::MOVZXr16r8,
1, TmpReg).addReg(SrcReg);
SrcTy = Type::ShortTy; // Pretend the short is our input now!
SrcClass = cShort;
SrcReg = TmpReg;
}
// Spill the integer to memory and reload it from there...
int FrameIdx =
F->getFrameInfo()->CreateStackObject(SrcTy, TM.getTargetData());
if (SrcClass == cLong) {
if (SrcTy == Type::ULongTy) visitInstruction(CI);
addFrameReference(BuildMI(BB, X86::MOVrm32, 5), FrameIdx).addReg(SrcReg);
addFrameReference(BuildMI(BB, X86::MOVrm32, 5),
FrameIdx, 4).addReg(SrcReg+1);
} else {
static const unsigned Op1[] = { X86::MOVrm8, X86::MOVrm16, X86::MOVrm32 };
addFrameReference(BuildMI(BB, Op1[SrcClass], 5), FrameIdx).addReg(SrcReg);
}
static const unsigned Op2[] =
{ 0, X86::FILDr16, X86::FILDr32, 0, X86::FILDr64 };
addFrameReference(BuildMI(BB, Op2[SrcClass], 5, DestReg), FrameIdx);
return;
}
// Handle casts from floating point to integer now...
if (SrcClass == cFP) {
// Change the floating point control register to use "round towards zero"
// mode when truncating to an integer value.
//
int CWFrameIdx = F->getFrameInfo()->CreateStackObject(2, 2);
addFrameReference(BuildMI(BB, X86::FNSTCWm16, 4), CWFrameIdx);
// Load the old value of the high byte of the control word...
unsigned HighPartOfCW = makeAnotherReg(Type::UByteTy);
addFrameReference(BuildMI(BB, X86::MOVmr8, 4, HighPartOfCW), CWFrameIdx, 1);
// Set the high part to be round to zero...
addFrameReference(BuildMI(BB, X86::MOVim8, 5), CWFrameIdx, 1).addZImm(12);
// Reload the modified control word now...
addFrameReference(BuildMI(BB, X86::FLDCWm16, 4), CWFrameIdx);
// Restore the memory image of control word to original value
addFrameReference(BuildMI(BB, X86::MOVrm8, 5),
CWFrameIdx, 1).addReg(HighPartOfCW);
// We don't have the facilities for directly storing byte sized data to
// memory. Promote it to 16 bits. We also must promote unsigned values to
// larger classes because we only have signed FP stores.
unsigned StoreClass = DestClass;
const Type *StoreTy = DestTy;
if (StoreClass == cByte || DestTy->isUnsigned())
switch (StoreClass) {
case cByte: StoreTy = Type::ShortTy; StoreClass = cShort; break;
case cShort: StoreTy = Type::IntTy; StoreClass = cInt; break;
case cInt: StoreTy = Type::LongTy; StoreClass = cLong; break;
case cLong: visitInstruction(CI); // unsigned long long -> more complex
default: assert(0 && "Unknown store class!");
}
// Spill the integer to memory and reload it from there...
int FrameIdx =
F->getFrameInfo()->CreateStackObject(StoreTy, TM.getTargetData());
static const unsigned Op1[] =
{ 0, X86::FISTr16, X86::FISTr32, 0, X86::FISTPr64 };
addFrameReference(BuildMI(BB, Op1[StoreClass], 5), FrameIdx).addReg(SrcReg);
if (DestClass == cLong) {
addFrameReference(BuildMI(BB, X86::MOVmr32, 4, DestReg), FrameIdx);
addFrameReference(BuildMI(BB, X86::MOVmr32, 4, DestReg+1), FrameIdx, 4);
} else {
static const unsigned Op2[] = { X86::MOVmr8, X86::MOVmr16, X86::MOVmr32 };
addFrameReference(BuildMI(BB, Op2[DestClass], 4, DestReg), FrameIdx);
}
// Reload the original control word now...
addFrameReference(BuildMI(BB, X86::FLDCWm16, 4), CWFrameIdx);
return;
}
// Anything we haven't handled already, we can't (yet) handle at all.
visitInstruction (CI);
}
// ExactLog2 - This function solves for (Val == 1 << (N-1)) and returns N. It
// returns zero when the input is not exactly a power of two.
static unsigned ExactLog2(unsigned Val) {
if (Val == 0) return 0;
unsigned Count = 0;
while (Val != 1) {
if (Val & 1) return 0;
Val >>= 1;
++Count;
}
return Count+1;
}
void ISel::visitGetElementPtrInst(GetElementPtrInst &I) {
unsigned outputReg = getReg(I);
MachineBasicBlock::iterator MI = BB->end();
emitGEPOperation(BB, MI, I.getOperand(0),
I.op_begin()+1, I.op_end(), outputReg);
}
void ISel::emitGEPOperation(MachineBasicBlock *MBB,
MachineBasicBlock::iterator &IP,
Value *Src, User::op_iterator IdxBegin,
User::op_iterator IdxEnd, unsigned TargetReg) {
const TargetData &TD = TM.getTargetData();
const Type *Ty = Src->getType();
unsigned BaseReg = getReg(Src, MBB, IP);
// GEPs have zero or more indices; we must perform a struct access
// or array access for each one.
for (GetElementPtrInst::op_iterator oi = IdxBegin,
oe = IdxEnd; oi != oe; ++oi) {
Value *idx = *oi;
unsigned NextReg = BaseReg;
if (const StructType *StTy = dyn_cast<StructType>(Ty)) {
// It's a struct access. idx is the index into the structure,
// which names the field. This index must have ubyte type.
const ConstantUInt *CUI = cast<ConstantUInt>(idx);
assert(CUI->getType() == Type::UByteTy
&& "Funny-looking structure index in GEP");
// Use the TargetData structure to pick out what the layout of
// the structure is in memory. Since the structure index must
// be constant, we can get its value and use it to find the
// right byte offset from the StructLayout class's list of
// structure member offsets.
unsigned idxValue = CUI->getValue();
unsigned FieldOff = TD.getStructLayout(StTy)->MemberOffsets[idxValue];
if (FieldOff) {
NextReg = makeAnotherReg(Type::UIntTy);
// Emit an ADD to add FieldOff to the basePtr.
BMI(MBB, IP, X86::ADDri32, 2,NextReg).addReg(BaseReg).addZImm(FieldOff);
}
// The next type is the member of the structure selected by the
// index.
Ty = StTy->getElementTypes()[idxValue];
} else if (const SequentialType *SqTy = cast<SequentialType>(Ty)) {
// It's an array or pointer access: [ArraySize x ElementType].
// idx is the index into the array. Unlike with structure
// indices, we may not know its actual value at code-generation
// time.
assert(idx->getType() == Type::LongTy && "Bad GEP array index!");
// We want to add BaseReg to(idxReg * sizeof ElementType). First, we
// must find the size of the pointed-to type (Not coincidentally, the next
// type is the type of the elements in the array).
Ty = SqTy->getElementType();
unsigned elementSize = TD.getTypeSize(Ty);
// If idxReg is a constant, we don't need to perform the multiply!
if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(idx)) {
if (!CSI->isNullValue()) {
unsigned Offset = elementSize*CSI->getValue();
NextReg = makeAnotherReg(Type::UIntTy);
BMI(MBB, IP, X86::ADDri32, 2,NextReg).addReg(BaseReg).addZImm(Offset);
}
} else if (elementSize == 1) {
// If the element size is 1, we don't have to multiply, just add
unsigned idxReg = getReg(idx, MBB, IP);
NextReg = makeAnotherReg(Type::UIntTy);
BMI(MBB, IP, X86::ADDrr32, 2, NextReg).addReg(BaseReg).addReg(idxReg);
} else {
unsigned idxReg = getReg(idx, MBB, IP);
unsigned OffsetReg = makeAnotherReg(Type::UIntTy);
if (unsigned Shift = ExactLog2(elementSize)) {
// If the element size is exactly a power of 2, use a shift to get it.
BMI(MBB, IP, X86::SHLir32, 2,
OffsetReg).addReg(idxReg).addZImm(Shift-1);
} else {
// Most general case, emit a multiply...
unsigned elementSizeReg = makeAnotherReg(Type::LongTy);
BMI(MBB, IP, X86::MOVir32, 1, elementSizeReg).addZImm(elementSize);
// Emit a MUL to multiply the register holding the index by
// elementSize, putting the result in OffsetReg.
doMultiply(MBB, IP, OffsetReg, Type::IntTy, idxReg, elementSizeReg);
}
// Emit an ADD to add OffsetReg to the basePtr.
NextReg = makeAnotherReg(Type::UIntTy);
BMI(MBB, IP, X86::ADDrr32, 2,NextReg).addReg(BaseReg).addReg(OffsetReg);
}
}
// Now that we are here, further indices refer to subtypes of this
// one, so we don't need to worry about BaseReg itself, anymore.
BaseReg = NextReg;
}
// After we have processed all the indices, the result is left in
// BaseReg. Move it to the register where we were expected to
// put the answer. A 32-bit move should do it, because we are in
// ILP32 land.
BMI(MBB, IP, X86::MOVrr32, 1, TargetReg).addReg(BaseReg);
}
/// visitAllocaInst - If this is a fixed size alloca, allocate space from the
/// frame manager, otherwise do it the hard way.
///
void ISel::visitAllocaInst(AllocaInst &I) {
// Find the data size of the alloca inst's getAllocatedType.
const Type *Ty = I.getAllocatedType();
unsigned TySize = TM.getTargetData().getTypeSize(Ty);
// If this is a fixed size alloca in the entry block for the function,
// statically stack allocate the space.
//
if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(I.getArraySize())) {
if (I.getParent() == I.getParent()->getParent()->begin()) {
TySize *= CUI->getValue(); // Get total allocated size...
unsigned Alignment = TM.getTargetData().getTypeAlignment(Ty);
// Create a new stack object using the frame manager...
int FrameIdx = F->getFrameInfo()->CreateStackObject(TySize, Alignment);
addFrameReference(BuildMI(BB, X86::LEAr32, 5, getReg(I)), FrameIdx);
return;
}
}
// Create a register to hold the temporary result of multiplying the type size
// constant by the variable amount.
unsigned TotalSizeReg = makeAnotherReg(Type::UIntTy);
unsigned SrcReg1 = getReg(I.getArraySize());
unsigned SizeReg = makeAnotherReg(Type::UIntTy);
BuildMI(BB, X86::MOVir32, 1, SizeReg).addZImm(TySize);
// TotalSizeReg = mul <numelements>, <TypeSize>
MachineBasicBlock::iterator MBBI = BB->end();
doMultiply(BB, MBBI, TotalSizeReg, Type::UIntTy, SrcReg1, SizeReg);
// AddedSize = add <TotalSizeReg>, 15
unsigned AddedSizeReg = makeAnotherReg(Type::UIntTy);
BuildMI(BB, X86::ADDri32, 2, AddedSizeReg).addReg(TotalSizeReg).addZImm(15);
// AlignedSize = and <AddedSize>, ~15
unsigned AlignedSize = makeAnotherReg(Type::UIntTy);
BuildMI(BB, X86::ANDri32, 2, AlignedSize).addReg(AddedSizeReg).addZImm(~15);
// Subtract size from stack pointer, thereby allocating some space.
BuildMI(BB, X86::SUBrr32, 2, X86::ESP).addReg(X86::ESP).addReg(AlignedSize);
// Put a pointer to the space into the result register, by copying
// the stack pointer.
BuildMI(BB, X86::MOVrr32, 1, getReg(I)).addReg(X86::ESP);
// Inform the Frame Information that we have just allocated a variable sized
// object.
F->getFrameInfo()->CreateVariableSizedObject();
}
/// visitMallocInst - Malloc instructions are code generated into direct calls
/// to the library malloc.
///
void ISel::visitMallocInst(MallocInst &I) {
unsigned AllocSize = TM.getTargetData().getTypeSize(I.getAllocatedType());
unsigned Arg;
if (ConstantUInt *C = dyn_cast<ConstantUInt>(I.getOperand(0))) {
Arg = getReg(ConstantUInt::get(Type::UIntTy, C->getValue() * AllocSize));
} else {
Arg = makeAnotherReg(Type::UIntTy);
unsigned Op0Reg = getReg(ConstantUInt::get(Type::UIntTy, AllocSize));
unsigned Op1Reg = getReg(I.getOperand(0));
MachineBasicBlock::iterator MBBI = BB->end();
doMultiply(BB, MBBI, Arg, Type::UIntTy, Op0Reg, Op1Reg);
}
std::vector<ValueRecord> Args;
Args.push_back(ValueRecord(Arg, Type::UIntTy));
MachineInstr *TheCall = BuildMI(X86::CALLpcrel32,
1).addExternalSymbol("malloc", true);
doCall(ValueRecord(getReg(I), I.getType()), TheCall, Args);
}
/// visitFreeInst - Free instructions are code gen'd to call the free libc
/// function.
///
void ISel::visitFreeInst(FreeInst &I) {
std::vector<ValueRecord> Args;
Args.push_back(ValueRecord(getReg(I.getOperand(0)),
I.getOperand(0)->getType()));
MachineInstr *TheCall = BuildMI(X86::CALLpcrel32,
1).addExternalSymbol("free", true);
doCall(ValueRecord(0, Type::VoidTy), TheCall, Args);
}
/// createSimpleX86InstructionSelector - This pass converts an LLVM function
/// into a machine code representation is a very simple peep-hole fashion. The
/// generated code sucks but the implementation is nice and simple.
///
Pass *createSimpleX86InstructionSelector(TargetMachine &TM) {
return new ISel(TM);
}
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