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/DerivedTypes.h"
18 #include "llvm/Function.h"
19 #include "llvm/Instructions.h"
20 #include "llvm/IntrinsicInst.h"
21 #include "llvm/LLVMContext.h"
22 #include "llvm/Module.h"
23 #include "llvm/Analysis/DebugInfo.h"
24 #include "llvm/CodeGen/Analysis.h"
25 #include "llvm/CodeGen/MachineFunction.h"
26 #include "llvm/CodeGen/MachineFrameInfo.h"
27 #include "llvm/CodeGen/MachineInstrBuilder.h"
28 #include "llvm/CodeGen/MachineModuleInfo.h"
29 #include "llvm/CodeGen/MachineRegisterInfo.h"
30 #include "llvm/Target/TargetRegisterInfo.h"
31 #include "llvm/Target/TargetData.h"
32 #include "llvm/Target/TargetInstrInfo.h"
33 #include "llvm/Target/TargetLowering.h"
34 #include "llvm/Target/TargetOptions.h"
35 #include "llvm/Support/Debug.h"
36 #include "llvm/Support/ErrorHandling.h"
37 #include "llvm/Support/MathExtras.h"
41 /// isUsedOutsideOfDefiningBlock - Return true if this instruction is used by
42 /// PHI nodes or outside of the basic block that defines it, or used by a
43 /// switch or atomic instruction, which may expand to multiple basic blocks.
44 static bool isUsedOutsideOfDefiningBlock(const Instruction *I) {
45 if (I->use_empty()) return false;
46 if (isa<PHINode>(I)) return true;
47 const BasicBlock *BB = I->getParent();
48 for (Value::const_use_iterator UI = I->use_begin(), E = I->use_end();
51 if (cast<Instruction>(U)->getParent() != BB || isa<PHINode>(U))
57 /// isOnlyUsedInEntryBlock - If the specified argument is only used in the
58 /// entry block, return true. This includes arguments used by switches, since
59 /// the switch may expand into multiple basic blocks.
60 static bool isOnlyUsedInEntryBlock(const Argument *A, bool EnableFastISel) {
61 // With FastISel active, we may be splitting blocks, so force creation
62 // of virtual registers for all non-dead arguments.
64 return A->use_empty();
66 const BasicBlock *Entry = A->getParent()->begin();
67 for (Value::const_use_iterator UI = A->use_begin(), E = A->use_end();
70 if (cast<Instruction>(U)->getParent() != Entry || isa<SwitchInst>(U))
71 return false; // Use not in entry block.
76 FunctionLoweringInfo::FunctionLoweringInfo(const TargetLowering &tli)
80 void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf) {
83 RegInfo = &MF->getRegInfo();
85 // Check whether the function can return without sret-demotion.
86 SmallVector<ISD::OutputArg, 4> Outs;
87 GetReturnInfo(Fn->getReturnType(),
88 Fn->getAttributes().getRetAttributes(), Outs, TLI);
89 CanLowerReturn = TLI.CanLowerReturn(Fn->getCallingConv(), Fn->isVarArg(),
90 Outs, Fn->getContext());
92 // Create a vreg for each argument register that is not dead and is used
93 // outside of the entry block for the function.
94 for (Function::const_arg_iterator AI = Fn->arg_begin(), E = Fn->arg_end();
96 if (!isOnlyUsedInEntryBlock(AI, EnableFastISel))
97 InitializeRegForValue(AI);
99 // Initialize the mapping of values to registers. This is only set up for
100 // instruction values that are used outside of the block that defines
102 Function::const_iterator BB = Fn->begin(), EB = Fn->end();
103 for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I)
104 if (const AllocaInst *AI = dyn_cast<AllocaInst>(I))
105 if (const ConstantInt *CUI = dyn_cast<ConstantInt>(AI->getArraySize())) {
106 const Type *Ty = AI->getAllocatedType();
107 uint64_t TySize = TLI.getTargetData()->getTypeAllocSize(Ty);
109 std::max((unsigned)TLI.getTargetData()->getPrefTypeAlignment(Ty),
112 TySize *= CUI->getZExtValue(); // Get total allocated size.
113 if (TySize == 0) TySize = 1; // Don't create zero-sized stack objects.
115 // The object may need to be placed onto the stack near the stack
116 // protector if one exists. Determine here if this object is a suitable
117 // candidate. I.e., it would trigger the creation of a stack protector.
119 (AI->isArrayAllocation() ||
120 (TySize > 8 && isa<ArrayType>(Ty) &&
121 cast<ArrayType>(Ty)->getElementType()->isIntegerTy(8)));
122 StaticAllocaMap[AI] =
123 MF->getFrameInfo()->CreateStackObject(TySize, Align, false, MayNeedSP);
126 for (; BB != EB; ++BB)
127 for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
128 // Mark values used outside their block as exported, by allocating
129 // a virtual register for them.
130 if (!EnableFastISel && isa<PHINode>(I)) {
131 PHIDestRegs.insert(InitializeRegForValue(I));
132 } else if (isUsedOutsideOfDefiningBlock(I)) {
133 if (!isa<AllocaInst>(I) ||
134 !StaticAllocaMap.count(cast<AllocaInst>(I)))
135 InitializeRegForValue(I);
138 // Collect llvm.dbg.declare information. This is done now instead of
139 // during the initial isel pass through the IR so that it is done
140 // in a predictable order.
141 if (const DbgDeclareInst *DI = dyn_cast<DbgDeclareInst>(I)) {
142 MachineModuleInfo &MMI = MF->getMMI();
143 if (MMI.hasDebugInfo() &&
144 DIVariable(DI->getVariable()).Verify() &&
145 !DI->getDebugLoc().isUnknown()) {
146 // Don't handle byval struct arguments or VLAs, for example.
147 // Non-byval arguments are handled here (they refer to the stack
148 // temporary alloca at this point).
149 const Value *Address = DI->getAddress();
151 if (const BitCastInst *BCI = dyn_cast<BitCastInst>(Address))
152 Address = BCI->getOperand(0);
153 if (const AllocaInst *AI = dyn_cast<AllocaInst>(Address)) {
154 DenseMap<const AllocaInst *, int>::iterator SI =
155 StaticAllocaMap.find(AI);
156 if (SI != StaticAllocaMap.end()) { // Check for VLAs.
158 MMI.setVariableDbgInfo(DI->getVariable(),
159 FI, DI->getDebugLoc());
167 // Create an initial MachineBasicBlock for each LLVM BasicBlock in F. This
168 // also creates the initial PHI MachineInstrs, though none of the input
169 // operands are populated.
170 for (BB = Fn->begin(); BB != EB; ++BB) {
171 MachineBasicBlock *MBB = mf.CreateMachineBasicBlock(BB);
175 // Transfer the address-taken flag. This is necessary because there could
176 // be multiple MachineBasicBlocks corresponding to one BasicBlock, and only
177 // the first one should be marked.
178 if (BB->hasAddressTaken())
179 MBB->setHasAddressTaken();
181 // Create Machine PHI nodes for LLVM PHI nodes, lowering them as
183 for (BasicBlock::const_iterator I = BB->begin();
184 const PHINode *PN = dyn_cast<PHINode>(I); ++I) {
185 if (PN->use_empty()) continue;
187 DebugLoc DL = PN->getDebugLoc();
188 unsigned PHIReg = ValueMap[PN];
189 assert(PHIReg && "PHI node does not have an assigned virtual register!");
191 SmallVector<EVT, 4> ValueVTs;
192 ComputeValueVTs(TLI, PN->getType(), ValueVTs);
193 for (unsigned vti = 0, vte = ValueVTs.size(); vti != vte; ++vti) {
194 EVT VT = ValueVTs[vti];
195 unsigned NumRegisters = TLI.getNumRegisters(Fn->getContext(), VT);
196 const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
197 for (unsigned i = 0; i != NumRegisters; ++i)
198 BuildMI(MBB, DL, TII->get(TargetOpcode::PHI), PHIReg + i);
199 PHIReg += NumRegisters;
204 // Mark landing pad blocks.
205 for (BB = Fn->begin(); BB != EB; ++BB)
206 if (const InvokeInst *Invoke = dyn_cast<InvokeInst>(BB->getTerminator()))
207 MBBMap[Invoke->getSuccessor(1)]->setIsLandingPad();
210 /// clear - Clear out all the function-specific state. This returns this
211 /// FunctionLoweringInfo to an empty state, ready to be used for a
212 /// different function.
213 void FunctionLoweringInfo::clear() {
214 assert(CatchInfoFound.size() == CatchInfoLost.size() &&
215 "Not all catch info was assigned to a landing pad!");
219 StaticAllocaMap.clear();
221 CatchInfoLost.clear();
222 CatchInfoFound.clear();
224 LiveOutRegInfo.clear();
227 PHISrcToDestMap.clear();
228 ArgDbgValues.clear();
229 ByValArgFrameIndexMap.clear();
233 /// CreateReg - Allocate a single virtual register for the given type.
234 unsigned FunctionLoweringInfo::CreateReg(EVT VT) {
235 return RegInfo->createVirtualRegister(TLI.getRegClassFor(VT));
238 /// CreateRegs - Allocate the appropriate number of virtual registers of
239 /// the correctly promoted or expanded types. Assign these registers
240 /// consecutive vreg numbers and return the first assigned number.
242 /// In the case that the given value has struct or array type, this function
243 /// will assign registers for each member or element.
245 unsigned FunctionLoweringInfo::CreateRegs(const Type *Ty) {
246 SmallVector<EVT, 4> ValueVTs;
247 ComputeValueVTs(TLI, Ty, ValueVTs);
249 unsigned FirstReg = 0;
250 for (unsigned Value = 0, e = ValueVTs.size(); Value != e; ++Value) {
251 EVT ValueVT = ValueVTs[Value];
252 EVT RegisterVT = TLI.getRegisterType(Ty->getContext(), ValueVT);
254 unsigned NumRegs = TLI.getNumRegisters(Ty->getContext(), ValueVT);
255 for (unsigned i = 0; i != NumRegs; ++i) {
256 unsigned R = CreateReg(RegisterVT);
257 if (!FirstReg) FirstReg = R;
263 /// setByValArgumentFrameIndex - Record frame index for the byval
264 /// argument. This overrides previous frame index entry for this argument,
266 void FunctionLoweringInfo::setByValArgumentFrameIndex(const Argument *A,
268 assert (A->hasByValAttr() && "Argument does not have byval attribute!");
269 ByValArgFrameIndexMap[A] = FI;
272 /// getByValArgumentFrameIndex - Get frame index for the byval argument.
273 /// If the argument does not have any assigned frame index then 0 is
275 int FunctionLoweringInfo::getByValArgumentFrameIndex(const Argument *A) {
276 assert (A->hasByValAttr() && "Argument does not have byval attribute!");
277 DenseMap<const Argument *, int>::iterator I =
278 ByValArgFrameIndexMap.find(A);
279 if (I != ByValArgFrameIndexMap.end())
281 DEBUG(dbgs() << "Argument does not have assigned frame index!");
285 /// AddCatchInfo - Extract the personality and type infos from an eh.selector
286 /// call, and add them to the specified machine basic block.
287 void llvm::AddCatchInfo(const CallInst &I, MachineModuleInfo *MMI,
288 MachineBasicBlock *MBB) {
289 // Inform the MachineModuleInfo of the personality for this landing pad.
290 const ConstantExpr *CE = cast<ConstantExpr>(I.getArgOperand(1));
291 assert(CE->getOpcode() == Instruction::BitCast &&
292 isa<Function>(CE->getOperand(0)) &&
293 "Personality should be a function");
294 MMI->addPersonality(MBB, cast<Function>(CE->getOperand(0)));
296 // Gather all the type infos for this landing pad and pass them along to
297 // MachineModuleInfo.
298 std::vector<const GlobalVariable *> TyInfo;
299 unsigned N = I.getNumArgOperands();
301 for (unsigned i = N - 1; i > 1; --i) {
302 if (const ConstantInt *CI = dyn_cast<ConstantInt>(I.getArgOperand(i))) {
303 unsigned FilterLength = CI->getZExtValue();
304 unsigned FirstCatch = i + FilterLength + !FilterLength;
305 assert(FirstCatch <= N && "Invalid filter length");
307 if (FirstCatch < N) {
308 TyInfo.reserve(N - FirstCatch);
309 for (unsigned j = FirstCatch; j < N; ++j)
310 TyInfo.push_back(ExtractTypeInfo(I.getArgOperand(j)));
311 MMI->addCatchTypeInfo(MBB, TyInfo);
317 MMI->addCleanup(MBB);
320 TyInfo.reserve(FilterLength - 1);
321 for (unsigned j = i + 1; j < FirstCatch; ++j)
322 TyInfo.push_back(ExtractTypeInfo(I.getArgOperand(j)));
323 MMI->addFilterTypeInfo(MBB, TyInfo);
332 TyInfo.reserve(N - 2);
333 for (unsigned j = 2; j < N; ++j)
334 TyInfo.push_back(ExtractTypeInfo(I.getArgOperand(j)));
335 MMI->addCatchTypeInfo(MBB, TyInfo);
339 void llvm::CopyCatchInfo(const BasicBlock *SrcBB, const BasicBlock *DestBB,
340 MachineModuleInfo *MMI, FunctionLoweringInfo &FLI) {
341 for (BasicBlock::const_iterator I = SrcBB->begin(), E = --SrcBB->end();
343 if (const EHSelectorInst *EHSel = dyn_cast<EHSelectorInst>(I)) {
344 // Apply the catch info to DestBB.
345 AddCatchInfo(*EHSel, MMI, FLI.MBBMap[DestBB]);
347 if (!FLI.MBBMap[SrcBB]->isLandingPad())
348 FLI.CatchInfoFound.insert(EHSel);