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/TargetFrameInfo.h"
33 #include "llvm/Target/TargetInstrInfo.h"
34 #include "llvm/Target/TargetLowering.h"
35 #include "llvm/Target/TargetOptions.h"
36 #include "llvm/Support/Debug.h"
37 #include "llvm/Support/ErrorHandling.h"
38 #include "llvm/Support/MathExtras.h"
42 /// isUsedOutsideOfDefiningBlock - Return true if this instruction is used by
43 /// PHI nodes or outside of the basic block that defines it, or used by a
44 /// switch or atomic instruction, which may expand to multiple basic blocks.
45 static bool isUsedOutsideOfDefiningBlock(const Instruction *I) {
46 if (I->use_empty()) return false;
47 if (isa<PHINode>(I)) return true;
48 const BasicBlock *BB = I->getParent();
49 for (Value::const_use_iterator UI = I->use_begin(), E = I->use_end();
52 if (cast<Instruction>(U)->getParent() != BB || isa<PHINode>(U))
58 /// isOnlyUsedInEntryBlock - If the specified argument is only used in the
59 /// entry block, return true. This includes arguments used by switches, since
60 /// the switch may expand into multiple basic blocks.
61 static bool isOnlyUsedInEntryBlock(const Argument *A, bool EnableFastISel) {
62 // With FastISel active, we may be splitting blocks, so force creation
63 // of virtual registers for all non-dead arguments.
65 return A->use_empty();
67 const BasicBlock *Entry = A->getParent()->begin();
68 for (Value::const_use_iterator UI = A->use_begin(), E = A->use_end();
71 if (cast<Instruction>(U)->getParent() != Entry || isa<SwitchInst>(U))
72 return false; // Use not in entry block.
77 FunctionLoweringInfo::FunctionLoweringInfo(const TargetLowering &tli)
81 void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf) {
84 RegInfo = &MF->getRegInfo();
86 // Check whether the function can return without sret-demotion.
87 SmallVector<ISD::OutputArg, 4> Outs;
88 GetReturnInfo(Fn->getReturnType(),
89 Fn->getAttributes().getRetAttributes(), Outs, TLI);
90 CanLowerReturn = TLI.CanLowerReturn(Fn->getCallingConv(), Fn->isVarArg(),
91 Outs, Fn->getContext());
93 // Create a vreg for each argument register that is not dead and is used
94 // outside of the entry block for the function.
95 for (Function::const_arg_iterator AI = Fn->arg_begin(), E = Fn->arg_end();
97 if (!isOnlyUsedInEntryBlock(AI, EnableFastISel))
98 InitializeRegForValue(AI);
100 // Initialize the mapping of values to registers. This is only set up for
101 // instruction values that are used outside of the block that defines
103 Function::const_iterator BB = Fn->begin(), EB = Fn->end();
104 for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I)
105 if (const AllocaInst *AI = dyn_cast<AllocaInst>(I))
106 if (const ConstantInt *CUI = dyn_cast<ConstantInt>(AI->getArraySize())) {
107 const Type *Ty = AI->getAllocatedType();
108 uint64_t TySize = TLI.getTargetData()->getTypeAllocSize(Ty);
110 std::max((unsigned)TLI.getTargetData()->getPrefTypeAlignment(Ty),
113 TySize *= CUI->getZExtValue(); // Get total allocated size.
114 if (TySize == 0) TySize = 1; // Don't create zero-sized stack objects.
115 StaticAllocaMap[AI] =
116 MF->getFrameInfo()->CreateStackObject(TySize, Align, false);
119 for (; BB != EB; ++BB)
120 for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
121 // Mark values used outside their block as exported, by allocating
122 // a virtual register for them.
123 if (isUsedOutsideOfDefiningBlock(I))
124 if (!isa<AllocaInst>(I) ||
125 !StaticAllocaMap.count(cast<AllocaInst>(I)))
126 InitializeRegForValue(I);
128 // Collect llvm.dbg.declare information. This is done now instead of
129 // during the initial isel pass through the IR so that it is done
130 // in a predictable order.
131 if (const DbgDeclareInst *DI = dyn_cast<DbgDeclareInst>(I)) {
132 MachineModuleInfo &MMI = MF->getMMI();
133 if (MMI.hasDebugInfo() &&
134 DIVariable(DI->getVariable()).Verify() &&
135 !DI->getDebugLoc().isUnknown()) {
136 // Don't handle byval struct arguments or VLAs, for example.
137 // Non-byval arguments are handled here (they refer to the stack
138 // temporary alloca at this point).
139 const Value *Address = DI->getAddress();
141 if (const BitCastInst *BCI = dyn_cast<BitCastInst>(Address))
142 Address = BCI->getOperand(0);
143 if (const AllocaInst *AI = dyn_cast<AllocaInst>(Address)) {
144 DenseMap<const AllocaInst *, int>::iterator SI =
145 StaticAllocaMap.find(AI);
146 if (SI != StaticAllocaMap.end()) { // Check for VLAs.
148 MMI.setVariableDbgInfo(DI->getVariable(),
149 FI, DI->getDebugLoc());
157 // Create an initial MachineBasicBlock for each LLVM BasicBlock in F. This
158 // also creates the initial PHI MachineInstrs, though none of the input
159 // operands are populated.
160 for (BB = Fn->begin(); BB != EB; ++BB) {
161 MachineBasicBlock *MBB = mf.CreateMachineBasicBlock(BB);
165 // Transfer the address-taken flag. This is necessary because there could
166 // be multiple MachineBasicBlocks corresponding to one BasicBlock, and only
167 // the first one should be marked.
168 if (BB->hasAddressTaken())
169 MBB->setHasAddressTaken();
171 // Create Machine PHI nodes for LLVM PHI nodes, lowering them as
173 for (BasicBlock::const_iterator I = BB->begin();
174 const PHINode *PN = dyn_cast<PHINode>(I); ++I) {
175 if (PN->use_empty()) continue;
177 DebugLoc DL = PN->getDebugLoc();
178 unsigned PHIReg = ValueMap[PN];
179 assert(PHIReg && "PHI node does not have an assigned virtual register!");
181 SmallVector<EVT, 4> ValueVTs;
182 ComputeValueVTs(TLI, PN->getType(), ValueVTs);
183 for (unsigned vti = 0, vte = ValueVTs.size(); vti != vte; ++vti) {
184 EVT VT = ValueVTs[vti];
185 unsigned NumRegisters = TLI.getNumRegisters(Fn->getContext(), VT);
186 const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
187 for (unsigned i = 0; i != NumRegisters; ++i)
188 BuildMI(MBB, DL, TII->get(TargetOpcode::PHI), PHIReg + i);
189 PHIReg += NumRegisters;
194 // Mark landing pad blocks.
195 for (BB = Fn->begin(); BB != EB; ++BB)
196 if (const InvokeInst *Invoke = dyn_cast<InvokeInst>(BB->getTerminator()))
197 MBBMap[Invoke->getSuccessor(1)]->setIsLandingPad();
200 /// clear - Clear out all the function-specific state. This returns this
201 /// FunctionLoweringInfo to an empty state, ready to be used for a
202 /// different function.
203 void FunctionLoweringInfo::clear() {
204 assert(CatchInfoFound.size() == CatchInfoLost.size() &&
205 "Not all catch info was assigned to a landing pad!");
209 StaticAllocaMap.clear();
211 CatchInfoLost.clear();
212 CatchInfoFound.clear();
214 LiveOutRegInfo.clear();
215 ArgDbgValues.clear();
219 /// CreateReg - Allocate a single virtual register for the given type.
220 unsigned FunctionLoweringInfo::CreateReg(EVT VT) {
221 return RegInfo->createVirtualRegister(TLI.getRegClassFor(VT));
224 /// CreateRegs - Allocate the appropriate number of virtual registers of
225 /// the correctly promoted or expanded types. Assign these registers
226 /// consecutive vreg numbers and return the first assigned number.
228 /// In the case that the given value has struct or array type, this function
229 /// will assign registers for each member or element.
231 unsigned FunctionLoweringInfo::CreateRegs(const Type *Ty) {
232 SmallVector<EVT, 4> ValueVTs;
233 ComputeValueVTs(TLI, Ty, ValueVTs);
235 unsigned FirstReg = 0;
236 for (unsigned Value = 0, e = ValueVTs.size(); Value != e; ++Value) {
237 EVT ValueVT = ValueVTs[Value];
238 EVT RegisterVT = TLI.getRegisterType(Ty->getContext(), ValueVT);
240 unsigned NumRegs = TLI.getNumRegisters(Ty->getContext(), ValueVT);
241 for (unsigned i = 0; i != NumRegs; ++i) {
242 unsigned R = CreateReg(RegisterVT);
243 if (!FirstReg) FirstReg = R;
249 /// AddCatchInfo - Extract the personality and type infos from an eh.selector
250 /// call, and add them to the specified machine basic block.
251 void llvm::AddCatchInfo(const CallInst &I, MachineModuleInfo *MMI,
252 MachineBasicBlock *MBB) {
253 // Inform the MachineModuleInfo of the personality for this landing pad.
254 const ConstantExpr *CE = cast<ConstantExpr>(I.getArgOperand(1));
255 assert(CE->getOpcode() == Instruction::BitCast &&
256 isa<Function>(CE->getOperand(0)) &&
257 "Personality should be a function");
258 MMI->addPersonality(MBB, cast<Function>(CE->getOperand(0)));
260 // Gather all the type infos for this landing pad and pass them along to
261 // MachineModuleInfo.
262 std::vector<const GlobalVariable *> TyInfo;
263 unsigned N = I.getNumArgOperands();
265 for (unsigned i = N - 1; i > 1; --i) {
266 if (const ConstantInt *CI = dyn_cast<ConstantInt>(I.getArgOperand(i))) {
267 unsigned FilterLength = CI->getZExtValue();
268 unsigned FirstCatch = i + FilterLength + !FilterLength;
269 assert(FirstCatch <= N && "Invalid filter length");
271 if (FirstCatch < N) {
272 TyInfo.reserve(N - FirstCatch);
273 for (unsigned j = FirstCatch; j < N; ++j)
274 TyInfo.push_back(ExtractTypeInfo(I.getArgOperand(j)));
275 MMI->addCatchTypeInfo(MBB, TyInfo);
281 MMI->addCleanup(MBB);
284 TyInfo.reserve(FilterLength - 1);
285 for (unsigned j = i + 1; j < FirstCatch; ++j)
286 TyInfo.push_back(ExtractTypeInfo(I.getArgOperand(j)));
287 MMI->addFilterTypeInfo(MBB, TyInfo);
296 TyInfo.reserve(N - 2);
297 for (unsigned j = 2; j < N; ++j)
298 TyInfo.push_back(ExtractTypeInfo(I.getArgOperand(j)));
299 MMI->addCatchTypeInfo(MBB, TyInfo);
303 void llvm::CopyCatchInfo(const BasicBlock *SrcBB, const BasicBlock *DestBB,
304 MachineModuleInfo *MMI, FunctionLoweringInfo &FLI) {
305 for (BasicBlock::const_iterator I = SrcBB->begin(), E = --SrcBB->end();
307 if (const EHSelectorInst *EHSel = dyn_cast<EHSelectorInst>(I)) {
308 // Apply the catch info to DestBB.
309 AddCatchInfo(*EHSel, MMI, FLI.MBBMap[DestBB]);
311 if (!FLI.MBBMap[SrcBB]->isLandingPad())
312 FLI.CatchInfoFound.insert(EHSel);