1 //===-- FunctionLoweringInfo.cpp ------------------------------------------===//
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 implements routines for translating functions from LLVM IR into
13 //===----------------------------------------------------------------------===//
15 #define DEBUG_TYPE "function-lowering-info"
16 #include "llvm/CodeGen/FunctionLoweringInfo.h"
17 #include "llvm/ADT/PostOrderIterator.h"
18 #include "llvm/CodeGen/Analysis.h"
19 #include "llvm/CodeGen/MachineFrameInfo.h"
20 #include "llvm/CodeGen/MachineFunction.h"
21 #include "llvm/CodeGen/MachineInstrBuilder.h"
22 #include "llvm/CodeGen/MachineModuleInfo.h"
23 #include "llvm/CodeGen/MachineRegisterInfo.h"
24 #include "llvm/DebugInfo.h"
25 #include "llvm/IR/DataLayout.h"
26 #include "llvm/IR/DerivedTypes.h"
27 #include "llvm/IR/Function.h"
28 #include "llvm/IR/Instructions.h"
29 #include "llvm/IR/IntrinsicInst.h"
30 #include "llvm/IR/LLVMContext.h"
31 #include "llvm/IR/Module.h"
32 #include "llvm/Support/Debug.h"
33 #include "llvm/Support/ErrorHandling.h"
34 #include "llvm/Support/MathExtras.h"
35 #include "llvm/Target/TargetInstrInfo.h"
36 #include "llvm/Target/TargetFrameLowering.h"
37 #include "llvm/Target/TargetLowering.h"
38 #include "llvm/Target/TargetOptions.h"
39 #include "llvm/Target/TargetRegisterInfo.h"
43 /// isUsedOutsideOfDefiningBlock - Return true if this instruction is used by
44 /// PHI nodes or outside of the basic block that defines it, or used by a
45 /// switch or atomic instruction, which may expand to multiple basic blocks.
46 static bool isUsedOutsideOfDefiningBlock(const Instruction *I) {
47 if (I->use_empty()) return false;
48 if (isa<PHINode>(I)) return true;
49 const BasicBlock *BB = I->getParent();
50 for (Value::const_use_iterator UI = I->use_begin(), E = I->use_end();
53 if (cast<Instruction>(U)->getParent() != BB || isa<PHINode>(U))
59 void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf,
61 const TargetLowering *TLI = TM.getTargetLowering();
65 RegInfo = &MF->getRegInfo();
67 // Check whether the function can return without sret-demotion.
68 SmallVector<ISD::OutputArg, 4> Outs;
69 GetReturnInfo(Fn->getReturnType(), Fn->getAttributes(), Outs, *TLI);
70 CanLowerReturn = TLI->CanLowerReturn(Fn->getCallingConv(), *MF,
72 Outs, Fn->getContext());
74 // Initialize the mapping of values to registers. This is only set up for
75 // instruction values that are used outside of the block that defines
77 Function::const_iterator BB = Fn->begin(), EB = Fn->end();
78 for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I)
79 if (const AllocaInst *AI = dyn_cast<AllocaInst>(I))
80 if (const ConstantInt *CUI = dyn_cast<ConstantInt>(AI->getArraySize())) {
81 Type *Ty = AI->getAllocatedType();
82 uint64_t TySize = TLI->getDataLayout()->getTypeAllocSize(Ty);
84 std::max((unsigned)TLI->getDataLayout()->getPrefTypeAlignment(Ty),
87 TySize *= CUI->getZExtValue(); // Get total allocated size.
88 if (TySize == 0) TySize = 1; // Don't create zero-sized stack objects.
90 // The object may need to be placed onto the stack near the stack
91 // protector if one exists. Determine here if this object is a suitable
92 // candidate. I.e., it would trigger the creation of a stack protector.
94 (AI->isArrayAllocation() ||
95 (TySize >= 8 && isa<ArrayType>(Ty) &&
96 cast<ArrayType>(Ty)->getElementType()->isIntegerTy(8)));
98 MF->getFrameInfo()->CreateStackObject(TySize, Align, false,
102 for (; BB != EB; ++BB)
103 for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
105 // Look for dynamic allocas.
106 if (const AllocaInst *AI = dyn_cast<AllocaInst>(I)) {
107 if (!AI->isStaticAlloca()) {
108 unsigned Align = std::max(
109 (unsigned)TLI->getDataLayout()->getPrefTypeAlignment(
110 AI->getAllocatedType()),
112 unsigned StackAlign = TM.getFrameLowering()->getStackAlignment();
113 if (Align <= StackAlign)
115 // Inform the Frame Information that we have variable-sized objects.
116 MF->getFrameInfo()->CreateVariableSizedObject(Align ? Align : 1, AI);
120 // Look for inline asm that clobbers the SP register.
121 if (isa<CallInst>(I) || isa<InvokeInst>(I)) {
122 ImmutableCallSite CS(I);
123 if (const InlineAsm *IA = dyn_cast<InlineAsm>(CS.getCalledValue())) {
124 unsigned SP = TLI->getStackPointerRegisterToSaveRestore();
125 std::vector<TargetLowering::AsmOperandInfo> Ops =
126 TLI->ParseConstraints(CS);
127 for (size_t I = 0, E = Ops.size(); I != E; ++I) {
128 TargetLowering::AsmOperandInfo &Op = Ops[I];
129 if (Op.Type == InlineAsm::isClobber) {
130 // Clobbers don't have SDValue operands, hence SDValue().
131 TLI->ComputeConstraintToUse(Op, SDValue(), DAG);
132 std::pair<unsigned, const TargetRegisterClass*> PhysReg =
133 TLI->getRegForInlineAsmConstraint(Op.ConstraintCode,
135 if (PhysReg.first == SP)
136 MF->getFrameInfo()->setHasInlineAsmWithSPAdjust(true);
142 // Mark values used outside their block as exported, by allocating
143 // a virtual register for them.
144 if (isUsedOutsideOfDefiningBlock(I))
145 if (!isa<AllocaInst>(I) ||
146 !StaticAllocaMap.count(cast<AllocaInst>(I)))
147 InitializeRegForValue(I);
149 // Collect llvm.dbg.declare information. This is done now instead of
150 // during the initial isel pass through the IR so that it is done
151 // in a predictable order.
152 if (const DbgDeclareInst *DI = dyn_cast<DbgDeclareInst>(I)) {
153 MachineModuleInfo &MMI = MF->getMMI();
154 DIVariable DIVar(DI->getVariable());
155 assert((!DIVar || DIVar.isVariable()) &&
156 "Variable in DbgDeclareInst should be either null or a DIVariable.");
157 if (MMI.hasDebugInfo() &&
159 !DI->getDebugLoc().isUnknown()) {
160 // Don't handle byval struct arguments or VLAs, for example.
161 // Non-byval arguments are handled here (they refer to the stack
162 // temporary alloca at this point).
163 const Value *Address = DI->getAddress();
165 if (const BitCastInst *BCI = dyn_cast<BitCastInst>(Address))
166 Address = BCI->getOperand(0);
167 if (const AllocaInst *AI = dyn_cast<AllocaInst>(Address)) {
168 DenseMap<const AllocaInst *, int>::iterator SI =
169 StaticAllocaMap.find(AI);
170 if (SI != StaticAllocaMap.end()) { // Check for VLAs.
172 MMI.setVariableDbgInfo(DI->getVariable(),
173 FI, DI->getDebugLoc());
181 // Create an initial MachineBasicBlock for each LLVM BasicBlock in F. This
182 // also creates the initial PHI MachineInstrs, though none of the input
183 // operands are populated.
184 for (BB = Fn->begin(); BB != EB; ++BB) {
185 MachineBasicBlock *MBB = mf.CreateMachineBasicBlock(BB);
189 // Transfer the address-taken flag. This is necessary because there could
190 // be multiple MachineBasicBlocks corresponding to one BasicBlock, and only
191 // the first one should be marked.
192 if (BB->hasAddressTaken())
193 MBB->setHasAddressTaken();
195 // Create Machine PHI nodes for LLVM PHI nodes, lowering them as
197 for (BasicBlock::const_iterator I = BB->begin();
198 const PHINode *PN = dyn_cast<PHINode>(I); ++I) {
199 if (PN->use_empty()) continue;
202 if (PN->getType()->isEmptyTy())
205 DebugLoc DL = PN->getDebugLoc();
206 unsigned PHIReg = ValueMap[PN];
207 assert(PHIReg && "PHI node does not have an assigned virtual register!");
209 SmallVector<EVT, 4> ValueVTs;
210 ComputeValueVTs(*TLI, PN->getType(), ValueVTs);
211 for (unsigned vti = 0, vte = ValueVTs.size(); vti != vte; ++vti) {
212 EVT VT = ValueVTs[vti];
213 unsigned NumRegisters = TLI->getNumRegisters(Fn->getContext(), VT);
214 const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
215 for (unsigned i = 0; i != NumRegisters; ++i)
216 BuildMI(MBB, DL, TII->get(TargetOpcode::PHI), PHIReg + i);
217 PHIReg += NumRegisters;
222 // Mark landing pad blocks.
223 for (BB = Fn->begin(); BB != EB; ++BB)
224 if (const InvokeInst *Invoke = dyn_cast<InvokeInst>(BB->getTerminator()))
225 MBBMap[Invoke->getSuccessor(1)]->setIsLandingPad();
228 /// clear - Clear out all the function-specific state. This returns this
229 /// FunctionLoweringInfo to an empty state, ready to be used for a
230 /// different function.
231 void FunctionLoweringInfo::clear() {
232 assert(CatchInfoFound.size() == CatchInfoLost.size() &&
233 "Not all catch info was assigned to a landing pad!");
237 StaticAllocaMap.clear();
239 CatchInfoLost.clear();
240 CatchInfoFound.clear();
242 LiveOutRegInfo.clear();
244 ArgDbgValues.clear();
245 ByValArgFrameIndexMap.clear();
249 /// CreateReg - Allocate a single virtual register for the given type.
250 unsigned FunctionLoweringInfo::CreateReg(MVT VT) {
252 createVirtualRegister(TM.getTargetLowering()->getRegClassFor(VT));
255 /// CreateRegs - Allocate the appropriate number of virtual registers of
256 /// the correctly promoted or expanded types. Assign these registers
257 /// consecutive vreg numbers and return the first assigned number.
259 /// In the case that the given value has struct or array type, this function
260 /// will assign registers for each member or element.
262 unsigned FunctionLoweringInfo::CreateRegs(Type *Ty) {
263 const TargetLowering *TLI = TM.getTargetLowering();
265 SmallVector<EVT, 4> ValueVTs;
266 ComputeValueVTs(*TLI, Ty, ValueVTs);
268 unsigned FirstReg = 0;
269 for (unsigned Value = 0, e = ValueVTs.size(); Value != e; ++Value) {
270 EVT ValueVT = ValueVTs[Value];
271 MVT RegisterVT = TLI->getRegisterType(Ty->getContext(), ValueVT);
273 unsigned NumRegs = TLI->getNumRegisters(Ty->getContext(), ValueVT);
274 for (unsigned i = 0; i != NumRegs; ++i) {
275 unsigned R = CreateReg(RegisterVT);
276 if (!FirstReg) FirstReg = R;
282 /// GetLiveOutRegInfo - Gets LiveOutInfo for a register, returning NULL if the
283 /// register is a PHI destination and the PHI's LiveOutInfo is not valid. If
284 /// the register's LiveOutInfo is for a smaller bit width, it is extended to
285 /// the larger bit width by zero extension. The bit width must be no smaller
286 /// than the LiveOutInfo's existing bit width.
287 const FunctionLoweringInfo::LiveOutInfo *
288 FunctionLoweringInfo::GetLiveOutRegInfo(unsigned Reg, unsigned BitWidth) {
289 if (!LiveOutRegInfo.inBounds(Reg))
292 LiveOutInfo *LOI = &LiveOutRegInfo[Reg];
296 if (BitWidth > LOI->KnownZero.getBitWidth()) {
297 LOI->NumSignBits = 1;
298 LOI->KnownZero = LOI->KnownZero.zextOrTrunc(BitWidth);
299 LOI->KnownOne = LOI->KnownOne.zextOrTrunc(BitWidth);
305 /// ComputePHILiveOutRegInfo - Compute LiveOutInfo for a PHI's destination
306 /// register based on the LiveOutInfo of its operands.
307 void FunctionLoweringInfo::ComputePHILiveOutRegInfo(const PHINode *PN) {
308 Type *Ty = PN->getType();
309 if (!Ty->isIntegerTy() || Ty->isVectorTy())
312 const TargetLowering *TLI = TM.getTargetLowering();
314 SmallVector<EVT, 1> ValueVTs;
315 ComputeValueVTs(*TLI, Ty, ValueVTs);
316 assert(ValueVTs.size() == 1 &&
317 "PHIs with non-vector integer types should have a single VT.");
318 EVT IntVT = ValueVTs[0];
320 if (TLI->getNumRegisters(PN->getContext(), IntVT) != 1)
322 IntVT = TLI->getTypeToTransformTo(PN->getContext(), IntVT);
323 unsigned BitWidth = IntVT.getSizeInBits();
325 unsigned DestReg = ValueMap[PN];
326 if (!TargetRegisterInfo::isVirtualRegister(DestReg))
328 LiveOutRegInfo.grow(DestReg);
329 LiveOutInfo &DestLOI = LiveOutRegInfo[DestReg];
331 Value *V = PN->getIncomingValue(0);
332 if (isa<UndefValue>(V) || isa<ConstantExpr>(V)) {
333 DestLOI.NumSignBits = 1;
334 APInt Zero(BitWidth, 0);
335 DestLOI.KnownZero = Zero;
336 DestLOI.KnownOne = Zero;
340 if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
341 APInt Val = CI->getValue().zextOrTrunc(BitWidth);
342 DestLOI.NumSignBits = Val.getNumSignBits();
343 DestLOI.KnownZero = ~Val;
344 DestLOI.KnownOne = Val;
346 assert(ValueMap.count(V) && "V should have been placed in ValueMap when its"
347 "CopyToReg node was created.");
348 unsigned SrcReg = ValueMap[V];
349 if (!TargetRegisterInfo::isVirtualRegister(SrcReg)) {
350 DestLOI.IsValid = false;
353 const LiveOutInfo *SrcLOI = GetLiveOutRegInfo(SrcReg, BitWidth);
355 DestLOI.IsValid = false;
361 assert(DestLOI.KnownZero.getBitWidth() == BitWidth &&
362 DestLOI.KnownOne.getBitWidth() == BitWidth &&
363 "Masks should have the same bit width as the type.");
365 for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i) {
366 Value *V = PN->getIncomingValue(i);
367 if (isa<UndefValue>(V) || isa<ConstantExpr>(V)) {
368 DestLOI.NumSignBits = 1;
369 APInt Zero(BitWidth, 0);
370 DestLOI.KnownZero = Zero;
371 DestLOI.KnownOne = Zero;
375 if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
376 APInt Val = CI->getValue().zextOrTrunc(BitWidth);
377 DestLOI.NumSignBits = std::min(DestLOI.NumSignBits, Val.getNumSignBits());
378 DestLOI.KnownZero &= ~Val;
379 DestLOI.KnownOne &= Val;
383 assert(ValueMap.count(V) && "V should have been placed in ValueMap when "
384 "its CopyToReg node was created.");
385 unsigned SrcReg = ValueMap[V];
386 if (!TargetRegisterInfo::isVirtualRegister(SrcReg)) {
387 DestLOI.IsValid = false;
390 const LiveOutInfo *SrcLOI = GetLiveOutRegInfo(SrcReg, BitWidth);
392 DestLOI.IsValid = false;
395 DestLOI.NumSignBits = std::min(DestLOI.NumSignBits, SrcLOI->NumSignBits);
396 DestLOI.KnownZero &= SrcLOI->KnownZero;
397 DestLOI.KnownOne &= SrcLOI->KnownOne;
401 /// setArgumentFrameIndex - Record frame index for the byval
402 /// argument. This overrides previous frame index entry for this argument,
404 void FunctionLoweringInfo::setArgumentFrameIndex(const Argument *A,
406 ByValArgFrameIndexMap[A] = FI;
409 /// getArgumentFrameIndex - Get frame index for the byval argument.
410 /// If the argument does not have any assigned frame index then 0 is
412 int FunctionLoweringInfo::getArgumentFrameIndex(const Argument *A) {
413 DenseMap<const Argument *, int>::iterator I =
414 ByValArgFrameIndexMap.find(A);
415 if (I != ByValArgFrameIndexMap.end())
417 DEBUG(dbgs() << "Argument does not have assigned frame index!\n");
421 /// ComputeUsesVAFloatArgument - Determine if any floating-point values are
422 /// being passed to this variadic function, and set the MachineModuleInfo's
423 /// usesVAFloatArgument flag if so. This flag is used to emit an undefined
424 /// reference to _fltused on Windows, which will link in MSVCRT's
425 /// floating-point support.
426 void llvm::ComputeUsesVAFloatArgument(const CallInst &I,
427 MachineModuleInfo *MMI)
429 FunctionType *FT = cast<FunctionType>(
430 I.getCalledValue()->getType()->getContainedType(0));
431 if (FT->isVarArg() && !MMI->usesVAFloatArgument()) {
432 for (unsigned i = 0, e = I.getNumArgOperands(); i != e; ++i) {
433 Type* T = I.getArgOperand(i)->getType();
434 for (po_iterator<Type*> i = po_begin(T), e = po_end(T);
436 if (i->isFloatingPointTy()) {
437 MMI->setUsesVAFloatArgument(true);
445 /// AddCatchInfo - Extract the personality and type infos from an eh.selector
446 /// call, and add them to the specified machine basic block.
447 void llvm::AddCatchInfo(const CallInst &I, MachineModuleInfo *MMI,
448 MachineBasicBlock *MBB) {
449 // Inform the MachineModuleInfo of the personality for this landing pad.
450 const ConstantExpr *CE = cast<ConstantExpr>(I.getArgOperand(1));
451 assert(CE->getOpcode() == Instruction::BitCast &&
452 isa<Function>(CE->getOperand(0)) &&
453 "Personality should be a function");
454 MMI->addPersonality(MBB, cast<Function>(CE->getOperand(0)));
456 // Gather all the type infos for this landing pad and pass them along to
457 // MachineModuleInfo.
458 std::vector<const GlobalVariable *> TyInfo;
459 unsigned N = I.getNumArgOperands();
461 for (unsigned i = N - 1; i > 1; --i) {
462 if (const ConstantInt *CI = dyn_cast<ConstantInt>(I.getArgOperand(i))) {
463 unsigned FilterLength = CI->getZExtValue();
464 unsigned FirstCatch = i + FilterLength + !FilterLength;
465 assert(FirstCatch <= N && "Invalid filter length");
467 if (FirstCatch < N) {
468 TyInfo.reserve(N - FirstCatch);
469 for (unsigned j = FirstCatch; j < N; ++j)
470 TyInfo.push_back(ExtractTypeInfo(I.getArgOperand(j)));
471 MMI->addCatchTypeInfo(MBB, TyInfo);
477 MMI->addCleanup(MBB);
480 TyInfo.reserve(FilterLength - 1);
481 for (unsigned j = i + 1; j < FirstCatch; ++j)
482 TyInfo.push_back(ExtractTypeInfo(I.getArgOperand(j)));
483 MMI->addFilterTypeInfo(MBB, TyInfo);
492 TyInfo.reserve(N - 2);
493 for (unsigned j = 2; j < N; ++j)
494 TyInfo.push_back(ExtractTypeInfo(I.getArgOperand(j)));
495 MMI->addCatchTypeInfo(MBB, TyInfo);
499 /// AddLandingPadInfo - Extract the exception handling information from the
500 /// landingpad instruction and add them to the specified machine module info.
501 void llvm::AddLandingPadInfo(const LandingPadInst &I, MachineModuleInfo &MMI,
502 MachineBasicBlock *MBB) {
503 MMI.addPersonality(MBB,
504 cast<Function>(I.getPersonalityFn()->stripPointerCasts()));
509 // FIXME: New EH - Add the clauses in reverse order. This isn't 100% correct,
510 // but we need to do it this way because of how the DWARF EH emitter
511 // processes the clauses.
512 for (unsigned i = I.getNumClauses(); i != 0; --i) {
513 Value *Val = I.getClause(i - 1);
514 if (I.isCatch(i - 1)) {
515 MMI.addCatchTypeInfo(MBB,
516 dyn_cast<GlobalVariable>(Val->stripPointerCasts()));
518 // Add filters in a list.
519 Constant *CVal = cast<Constant>(Val);
520 SmallVector<const GlobalVariable*, 4> FilterList;
521 for (User::op_iterator
522 II = CVal->op_begin(), IE = CVal->op_end(); II != IE; ++II)
523 FilterList.push_back(cast<GlobalVariable>((*II)->stripPointerCasts()));
525 MMI.addFilterTypeInfo(MBB, FilterList);