1 ///===-- FastISel.cpp - Implementation of the FastISel class --------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains the implementation of the FastISel class.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/Instructions.h"
15 #include "llvm/CodeGen/FastISel.h"
16 #include "llvm/CodeGen/MachineInstrBuilder.h"
17 #include "llvm/CodeGen/MachineRegisterInfo.h"
18 #include "llvm/Target/TargetData.h"
19 #include "llvm/Target/TargetInstrInfo.h"
20 #include "llvm/Target/TargetLowering.h"
21 #include "llvm/Target/TargetMachine.h"
24 unsigned FastISel::getRegForValue(Value *V, DenseMap<const Value*, unsigned> &ValueMap) {
25 unsigned &Reg = ValueMap[V];
29 MVT::SimpleValueType VT = TLI.getValueType(V->getType()).getSimpleVT();
30 if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
31 if (CI->getValue().getActiveBits() > 64)
33 Reg = FastEmit_i(VT, VT, ISD::Constant, CI->getZExtValue());
34 } else if (isa<ConstantPointerNull>(V)) {
35 Reg = FastEmit_i(VT, VT, ISD::Constant, 0);
36 } else if (ConstantFP *CF = dyn_cast<ConstantFP>(V)) {
37 Reg = FastEmit_f(VT, VT, ISD::ConstantFP, CF);
40 const APFloat &Flt = CF->getValueAPF();
41 MVT IntVT = TLI.getPointerTy();
44 uint32_t IntBitWidth = IntVT.getSizeInBits();
45 if (Flt.convertToInteger(x, IntBitWidth, /*isSigned=*/true,
46 APFloat::rmTowardZero) != APFloat::opOK)
48 APInt IntVal(IntBitWidth, 2, x);
50 unsigned IntegerReg = FastEmit_i(IntVT.getSimpleVT(), IntVT.getSimpleVT(),
51 ISD::Constant, IntVal.getZExtValue());
54 Reg = FastEmit_r(IntVT.getSimpleVT(), VT, ISD::SINT_TO_FP, IntegerReg);
58 } else if (isa<UndefValue>(V)) {
59 Reg = createResultReg(TLI.getRegClassFor(VT));
60 BuildMI(MBB, TII.get(TargetInstrInfo::IMPLICIT_DEF), Reg);
66 /// SelectBinaryOp - Select and emit code for a binary operator instruction,
67 /// which has an opcode which directly corresponds to the given ISD opcode.
69 bool FastISel::SelectBinaryOp(Instruction *I, ISD::NodeType ISDOpcode,
70 DenseMap<const Value*, unsigned> &ValueMap) {
71 MVT VT = MVT::getMVT(I->getType(), /*HandleUnknown=*/true);
72 if (VT == MVT::Other || !VT.isSimple())
73 // Unhandled type. Halt "fast" selection and bail.
75 // We only handle legal types. For example, on x86-32 the instruction
76 // selector contains all of the 64-bit instructions from x86-64,
77 // under the assumption that i64 won't be used if the target doesn't
79 if (!TLI.isTypeLegal(VT))
82 unsigned Op0 = getRegForValue(I->getOperand(0), ValueMap);
84 // Unhandled operand. Halt "fast" selection and bail.
87 // Check if the second operand is a constant and handle it appropriately.
88 if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
89 unsigned ResultReg = FastEmit_ri(VT.getSimpleVT(), VT.getSimpleVT(),
90 ISDOpcode, Op0, CI->getZExtValue());
92 // We successfully emitted code for the given LLVM Instruction.
93 ValueMap[I] = ResultReg;
98 // Check if the second operand is a constant float.
99 if (ConstantFP *CF = dyn_cast<ConstantFP>(I->getOperand(1))) {
100 unsigned ResultReg = FastEmit_rf(VT.getSimpleVT(), VT.getSimpleVT(),
102 if (ResultReg != 0) {
103 // We successfully emitted code for the given LLVM Instruction.
104 ValueMap[I] = ResultReg;
109 unsigned Op1 = getRegForValue(I->getOperand(1), ValueMap);
111 // Unhandled operand. Halt "fast" selection and bail.
114 // Now we have both operands in registers. Emit the instruction.
115 unsigned ResultReg = FastEmit_rr(VT.getSimpleVT(), VT.getSimpleVT(),
116 ISDOpcode, Op0, Op1);
118 // Target-specific code wasn't able to find a machine opcode for
119 // the given ISD opcode and type. Halt "fast" selection and bail.
122 // We successfully emitted code for the given LLVM Instruction.
123 ValueMap[I] = ResultReg;
127 bool FastISel::SelectGetElementPtr(Instruction *I,
128 DenseMap<const Value*, unsigned> &ValueMap) {
129 unsigned N = getRegForValue(I->getOperand(0), ValueMap);
131 // Unhandled operand. Halt "fast" selection and bail.
134 const Type *Ty = I->getOperand(0)->getType();
135 MVT::SimpleValueType VT = TLI.getPointerTy().getSimpleVT();
136 for (GetElementPtrInst::op_iterator OI = I->op_begin()+1, E = I->op_end();
139 if (const StructType *StTy = dyn_cast<StructType>(Ty)) {
140 unsigned Field = cast<ConstantInt>(Idx)->getZExtValue();
143 uint64_t Offs = TD.getStructLayout(StTy)->getElementOffset(Field);
144 // FIXME: This can be optimized by combining the add with a
146 N = FastEmit_ri_(VT, ISD::ADD, N, Offs, VT);
148 // Unhandled operand. Halt "fast" selection and bail.
151 Ty = StTy->getElementType(Field);
153 Ty = cast<SequentialType>(Ty)->getElementType();
155 // If this is a constant subscript, handle it quickly.
156 if (ConstantInt *CI = dyn_cast<ConstantInt>(Idx)) {
157 if (CI->getZExtValue() == 0) continue;
159 TD.getABITypeSize(Ty)*cast<ConstantInt>(CI)->getSExtValue();
160 N = FastEmit_ri_(VT, ISD::ADD, N, Offs, VT);
162 // Unhandled operand. Halt "fast" selection and bail.
167 // N = N + Idx * ElementSize;
168 uint64_t ElementSize = TD.getABITypeSize(Ty);
169 unsigned IdxN = getRegForValue(Idx, ValueMap);
171 // Unhandled operand. Halt "fast" selection and bail.
174 // If the index is smaller or larger than intptr_t, truncate or extend
176 MVT IdxVT = MVT::getMVT(Idx->getType(), /*HandleUnknown=*/false);
177 if (IdxVT.bitsLT(VT))
178 IdxN = FastEmit_r(IdxVT.getSimpleVT(), VT, ISD::SIGN_EXTEND, IdxN);
179 else if (IdxVT.bitsGT(VT))
180 IdxN = FastEmit_r(IdxVT.getSimpleVT(), VT, ISD::TRUNCATE, IdxN);
182 // Unhandled operand. Halt "fast" selection and bail.
185 if (ElementSize != 1) {
186 IdxN = FastEmit_ri_(VT, ISD::MUL, IdxN, ElementSize, VT);
188 // Unhandled operand. Halt "fast" selection and bail.
191 N = FastEmit_rr(VT, VT, ISD::ADD, N, IdxN);
193 // Unhandled operand. Halt "fast" selection and bail.
198 // We successfully emitted code for the given LLVM Instruction.
203 bool FastISel::SelectCast(Instruction *I, ISD::NodeType Opcode,
204 DenseMap<const Value*, unsigned> &ValueMap) {
205 MVT SrcVT = TLI.getValueType(I->getOperand(0)->getType());
206 MVT DstVT = TLI.getValueType(I->getType());
208 if (SrcVT == MVT::Other || !SrcVT.isSimple() ||
209 DstVT == MVT::Other || !DstVT.isSimple() ||
210 !TLI.isTypeLegal(SrcVT) || !TLI.isTypeLegal(DstVT))
211 // Unhandled type. Halt "fast" selection and bail.
214 unsigned InputReg = getRegForValue(I->getOperand(0), ValueMap);
216 // Unhandled operand. Halt "fast" selection and bail.
219 unsigned ResultReg = FastEmit_r(SrcVT.getSimpleVT(),
226 ValueMap[I] = ResultReg;
230 bool FastISel::SelectBitCast(Instruction *I,
231 DenseMap<const Value*, unsigned> &ValueMap) {
232 // If the bitcast doesn't change the type, just use the operand value.
233 if (I->getType() == I->getOperand(0)->getType()) {
234 unsigned Reg = getRegForValue(I->getOperand(0), ValueMap);
241 // Bitcasts of other values become reg-reg copies or BIT_CONVERT operators.
242 MVT SrcVT = TLI.getValueType(I->getOperand(0)->getType());
243 MVT DstVT = TLI.getValueType(I->getType());
245 if (SrcVT == MVT::Other || !SrcVT.isSimple() ||
246 DstVT == MVT::Other || !DstVT.isSimple() ||
247 !TLI.isTypeLegal(SrcVT) || !TLI.isTypeLegal(DstVT))
248 // Unhandled type. Halt "fast" selection and bail.
251 unsigned Op0 = getRegForValue(I->getOperand(0), ValueMap);
253 // Unhandled operand. Halt "fast" selection and bail.
256 // First, try to perform the bitcast by inserting a reg-reg copy.
257 unsigned ResultReg = 0;
258 if (SrcVT.getSimpleVT() == DstVT.getSimpleVT()) {
259 TargetRegisterClass* SrcClass = TLI.getRegClassFor(SrcVT);
260 TargetRegisterClass* DstClass = TLI.getRegClassFor(DstVT);
261 ResultReg = createResultReg(DstClass);
263 bool InsertedCopy = TII.copyRegToReg(*MBB, MBB->end(), ResultReg,
264 Op0, DstClass, SrcClass);
269 // If the reg-reg copy failed, select a BIT_CONVERT opcode.
271 ResultReg = FastEmit_r(SrcVT.getSimpleVT(), DstVT.getSimpleVT(),
272 ISD::BIT_CONVERT, Op0);
277 ValueMap[I] = ResultReg;
282 FastISel::SelectInstructions(BasicBlock::iterator Begin,
283 BasicBlock::iterator End,
284 DenseMap<const Value*, unsigned> &ValueMap,
285 DenseMap<const BasicBlock*,
286 MachineBasicBlock *> &MBBMap,
287 MachineBasicBlock *mbb) {
289 BasicBlock::iterator I = Begin;
291 for (; I != End; ++I) {
292 switch (I->getOpcode()) {
293 case Instruction::Add: {
294 ISD::NodeType Opc = I->getType()->isFPOrFPVector() ? ISD::FADD : ISD::ADD;
295 if (!SelectBinaryOp(I, Opc, ValueMap)) return I; break;
297 case Instruction::Sub: {
298 ISD::NodeType Opc = I->getType()->isFPOrFPVector() ? ISD::FSUB : ISD::SUB;
299 if (!SelectBinaryOp(I, Opc, ValueMap)) return I; break;
301 case Instruction::Mul: {
302 ISD::NodeType Opc = I->getType()->isFPOrFPVector() ? ISD::FMUL : ISD::MUL;
303 if (!SelectBinaryOp(I, Opc, ValueMap)) return I; break;
305 case Instruction::SDiv:
306 if (!SelectBinaryOp(I, ISD::SDIV, ValueMap)) return I; break;
307 case Instruction::UDiv:
308 if (!SelectBinaryOp(I, ISD::UDIV, ValueMap)) return I; break;
309 case Instruction::FDiv:
310 if (!SelectBinaryOp(I, ISD::FDIV, ValueMap)) return I; break;
311 case Instruction::SRem:
312 if (!SelectBinaryOp(I, ISD::SREM, ValueMap)) return I; break;
313 case Instruction::URem:
314 if (!SelectBinaryOp(I, ISD::UREM, ValueMap)) return I; break;
315 case Instruction::FRem:
316 if (!SelectBinaryOp(I, ISD::FREM, ValueMap)) return I; break;
317 case Instruction::Shl:
318 if (!SelectBinaryOp(I, ISD::SHL, ValueMap)) return I; break;
319 case Instruction::LShr:
320 if (!SelectBinaryOp(I, ISD::SRL, ValueMap)) return I; break;
321 case Instruction::AShr:
322 if (!SelectBinaryOp(I, ISD::SRA, ValueMap)) return I; break;
323 case Instruction::And:
324 if (!SelectBinaryOp(I, ISD::AND, ValueMap)) return I; break;
325 case Instruction::Or:
326 if (!SelectBinaryOp(I, ISD::OR, ValueMap)) return I; break;
327 case Instruction::Xor:
328 if (!SelectBinaryOp(I, ISD::XOR, ValueMap)) return I; break;
330 case Instruction::GetElementPtr:
331 if (!SelectGetElementPtr(I, ValueMap)) return I;
334 case Instruction::Br: {
335 BranchInst *BI = cast<BranchInst>(I);
337 if (BI->isUnconditional()) {
338 MachineFunction::iterator NextMBB =
339 next(MachineFunction::iterator(MBB));
340 BasicBlock *LLVMSucc = BI->getSuccessor(0);
341 MachineBasicBlock *MSucc = MBBMap[LLVMSucc];
343 if (NextMBB != MF.end() && MSucc == NextMBB) {
344 // The unconditional fall-through case, which needs no instructions.
346 // The unconditional branch case.
347 TII.InsertBranch(*MBB, MSucc, NULL, SmallVector<MachineOperand, 0>());
349 MBB->addSuccessor(MSucc);
353 // Conditional branches are not handed yet.
354 // Halt "fast" selection and bail.
358 case Instruction::PHI:
359 // PHI nodes are already emitted.
362 case Instruction::BitCast:
363 if (!SelectBitCast(I, ValueMap)) return I; break;
365 case Instruction::FPToSI:
366 if (!SelectCast(I, ISD::FP_TO_SINT, ValueMap)) return I;
368 case Instruction::ZExt:
369 if (!SelectCast(I, ISD::ZERO_EXTEND, ValueMap)) return I;
371 case Instruction::SExt:
372 if (!SelectCast(I, ISD::SIGN_EXTEND, ValueMap)) return I;
374 case Instruction::Trunc:
375 if (!SelectCast(I, ISD::TRUNCATE, ValueMap)) return I;
377 case Instruction::SIToFP:
378 if (!SelectCast(I, ISD::SINT_TO_FP, ValueMap)) return I;
381 case Instruction::IntToPtr: // Deliberate fall-through.
382 case Instruction::PtrToInt: {
383 MVT SrcVT = TLI.getValueType(I->getOperand(0)->getType());
384 MVT DstVT = TLI.getValueType(I->getType());
385 if (SrcVT.getSimpleVT() == DstVT.getSimpleVT()) {
386 if (ValueMap[I->getOperand(0)]) {
387 ValueMap[I] = ValueMap[I->getOperand(0)];
392 } else if (DstVT.bitsGT(SrcVT)) {
393 if (!SelectCast(I, ISD::ZERO_EXTEND, ValueMap)) return I;
396 // TODO: Handle SrcVT > DstVT, where truncation is needed.
402 // Unhandled instruction. Halt "fast" selection and bail.
410 FastISel::FastISel(MachineFunction &mf)
412 MRI(mf.getRegInfo()),
414 TD(*TM.getTargetData()),
415 TII(*TM.getInstrInfo()),
416 TLI(*TM.getTargetLowering()) {
419 FastISel::~FastISel() {}
421 unsigned FastISel::FastEmit_(MVT::SimpleValueType, MVT::SimpleValueType, ISD::NodeType) {
425 unsigned FastISel::FastEmit_r(MVT::SimpleValueType, MVT::SimpleValueType,
426 ISD::NodeType, unsigned /*Op0*/) {
430 unsigned FastISel::FastEmit_rr(MVT::SimpleValueType, MVT::SimpleValueType,
431 ISD::NodeType, unsigned /*Op0*/,
436 unsigned FastISel::FastEmit_i(MVT::SimpleValueType, MVT::SimpleValueType,
437 ISD::NodeType, uint64_t /*Imm*/) {
441 unsigned FastISel::FastEmit_f(MVT::SimpleValueType, MVT::SimpleValueType,
442 ISD::NodeType, ConstantFP * /*FPImm*/) {
446 unsigned FastISel::FastEmit_ri(MVT::SimpleValueType, MVT::SimpleValueType,
447 ISD::NodeType, unsigned /*Op0*/,
452 unsigned FastISel::FastEmit_rf(MVT::SimpleValueType, MVT::SimpleValueType,
453 ISD::NodeType, unsigned /*Op0*/,
454 ConstantFP * /*FPImm*/) {
458 unsigned FastISel::FastEmit_rri(MVT::SimpleValueType, MVT::SimpleValueType,
460 unsigned /*Op0*/, unsigned /*Op1*/,
465 /// FastEmit_ri_ - This method is a wrapper of FastEmit_ri. It first tries
466 /// to emit an instruction with an immediate operand using FastEmit_ri.
467 /// If that fails, it materializes the immediate into a register and try
468 /// FastEmit_rr instead.
469 unsigned FastISel::FastEmit_ri_(MVT::SimpleValueType VT, ISD::NodeType Opcode,
470 unsigned Op0, uint64_t Imm,
471 MVT::SimpleValueType ImmType) {
472 // First check if immediate type is legal. If not, we can't use the ri form.
473 unsigned ResultReg = FastEmit_ri(VT, VT, Opcode, Op0, Imm);
476 unsigned MaterialReg = FastEmit_i(ImmType, ImmType, ISD::Constant, Imm);
477 if (MaterialReg == 0)
479 return FastEmit_rr(VT, VT, Opcode, Op0, MaterialReg);
482 /// FastEmit_rf_ - This method is a wrapper of FastEmit_ri. It first tries
483 /// to emit an instruction with a floating-point immediate operand using
484 /// FastEmit_rf. If that fails, it materializes the immediate into a register
485 /// and try FastEmit_rr instead.
486 unsigned FastISel::FastEmit_rf_(MVT::SimpleValueType VT, ISD::NodeType Opcode,
487 unsigned Op0, ConstantFP *FPImm,
488 MVT::SimpleValueType ImmType) {
489 // First check if immediate type is legal. If not, we can't use the rf form.
490 unsigned ResultReg = FastEmit_rf(VT, VT, Opcode, Op0, FPImm);
494 // Materialize the constant in a register.
495 unsigned MaterialReg = FastEmit_f(ImmType, ImmType, ISD::ConstantFP, FPImm);
496 if (MaterialReg == 0) {
497 // If the target doesn't have a way to directly enter a floating-point
498 // value into a register, use an alternate approach.
499 // TODO: The current approach only supports floating-point constants
500 // that can be constructed by conversion from integer values. This should
501 // be replaced by code that creates a load from a constant-pool entry,
502 // which will require some target-specific work.
503 const APFloat &Flt = FPImm->getValueAPF();
504 MVT IntVT = TLI.getPointerTy();
507 uint32_t IntBitWidth = IntVT.getSizeInBits();
508 if (Flt.convertToInteger(x, IntBitWidth, /*isSigned=*/true,
509 APFloat::rmTowardZero) != APFloat::opOK)
511 APInt IntVal(IntBitWidth, 2, x);
513 unsigned IntegerReg = FastEmit_i(IntVT.getSimpleVT(), IntVT.getSimpleVT(),
514 ISD::Constant, IntVal.getZExtValue());
517 MaterialReg = FastEmit_r(IntVT.getSimpleVT(), VT,
518 ISD::SINT_TO_FP, IntegerReg);
519 if (MaterialReg == 0)
522 return FastEmit_rr(VT, VT, Opcode, Op0, MaterialReg);
525 unsigned FastISel::createResultReg(const TargetRegisterClass* RC) {
526 return MRI.createVirtualRegister(RC);
529 unsigned FastISel::FastEmitInst_(unsigned MachineInstOpcode,
530 const TargetRegisterClass* RC) {
531 unsigned ResultReg = createResultReg(RC);
532 const TargetInstrDesc &II = TII.get(MachineInstOpcode);
534 BuildMI(MBB, II, ResultReg);
538 unsigned FastISel::FastEmitInst_r(unsigned MachineInstOpcode,
539 const TargetRegisterClass *RC,
541 unsigned ResultReg = createResultReg(RC);
542 const TargetInstrDesc &II = TII.get(MachineInstOpcode);
544 BuildMI(MBB, II, ResultReg).addReg(Op0);
548 unsigned FastISel::FastEmitInst_rr(unsigned MachineInstOpcode,
549 const TargetRegisterClass *RC,
550 unsigned Op0, unsigned Op1) {
551 unsigned ResultReg = createResultReg(RC);
552 const TargetInstrDesc &II = TII.get(MachineInstOpcode);
554 BuildMI(MBB, II, ResultReg).addReg(Op0).addReg(Op1);
558 unsigned FastISel::FastEmitInst_ri(unsigned MachineInstOpcode,
559 const TargetRegisterClass *RC,
560 unsigned Op0, uint64_t Imm) {
561 unsigned ResultReg = createResultReg(RC);
562 const TargetInstrDesc &II = TII.get(MachineInstOpcode);
564 BuildMI(MBB, II, ResultReg).addReg(Op0).addImm(Imm);
568 unsigned FastISel::FastEmitInst_rf(unsigned MachineInstOpcode,
569 const TargetRegisterClass *RC,
570 unsigned Op0, ConstantFP *FPImm) {
571 unsigned ResultReg = createResultReg(RC);
572 const TargetInstrDesc &II = TII.get(MachineInstOpcode);
574 BuildMI(MBB, II, ResultReg).addReg(Op0).addFPImm(FPImm);
578 unsigned FastISel::FastEmitInst_rri(unsigned MachineInstOpcode,
579 const TargetRegisterClass *RC,
580 unsigned Op0, unsigned Op1, uint64_t Imm) {
581 unsigned ResultReg = createResultReg(RC);
582 const TargetInstrDesc &II = TII.get(MachineInstOpcode);
584 BuildMI(MBB, II, ResultReg).addReg(Op0).addReg(Op1).addImm(Imm);
588 unsigned FastISel::FastEmitInst_i(unsigned MachineInstOpcode,
589 const TargetRegisterClass *RC,
591 unsigned ResultReg = createResultReg(RC);
592 const TargetInstrDesc &II = TII.get(MachineInstOpcode);
594 BuildMI(MBB, II, ResultReg).addImm(Imm);
598 unsigned FastISel::FastEmitInst_extractsubreg(unsigned Op0, uint32_t Idx) {
599 const TargetRegisterClass* RC = MRI.getRegClass(Op0);
600 const TargetRegisterClass* SRC = *(RC->subregclasses_begin()+Idx-1);
602 unsigned ResultReg = createResultReg(SRC);
603 const TargetInstrDesc &II = TII.get(TargetInstrInfo::EXTRACT_SUBREG);
605 BuildMI(MBB, II, ResultReg).addReg(Op0).addImm(Idx);