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/CodeGen/Analysis.h"
24 #include "llvm/CodeGen/MachineFunction.h"
25 #include "llvm/CodeGen/MachineFrameInfo.h"
26 #include "llvm/CodeGen/MachineInstrBuilder.h"
27 #include "llvm/CodeGen/MachineModuleInfo.h"
28 #include "llvm/CodeGen/MachineRegisterInfo.h"
29 #include "llvm/Target/TargetRegisterInfo.h"
30 #include "llvm/Target/TargetData.h"
31 #include "llvm/Target/TargetFrameInfo.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.
114 StaticAllocaMap[AI] =
115 MF->getFrameInfo()->CreateStackObject(TySize, Align, false);
118 for (; BB != EB; ++BB)
119 for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I)
120 if (isUsedOutsideOfDefiningBlock(I))
121 if (!isa<AllocaInst>(I) ||
122 !StaticAllocaMap.count(cast<AllocaInst>(I)))
123 InitializeRegForValue(I);
125 // Create an initial MachineBasicBlock for each LLVM BasicBlock in F. This
126 // also creates the initial PHI MachineInstrs, though none of the input
127 // operands are populated.
128 for (BB = Fn->begin(); BB != EB; ++BB) {
129 MachineBasicBlock *MBB = mf.CreateMachineBasicBlock(BB);
133 // Transfer the address-taken flag. This is necessary because there could
134 // be multiple MachineBasicBlocks corresponding to one BasicBlock, and only
135 // the first one should be marked.
136 if (BB->hasAddressTaken())
137 MBB->setHasAddressTaken();
139 // Create Machine PHI nodes for LLVM PHI nodes, lowering them as
141 for (BasicBlock::const_iterator I = BB->begin();
142 const PHINode *PN = dyn_cast<PHINode>(I); ++I) {
143 if (PN->use_empty()) continue;
145 DebugLoc DL = PN->getDebugLoc();
146 unsigned PHIReg = ValueMap[PN];
147 assert(PHIReg && "PHI node does not have an assigned virtual register!");
149 SmallVector<EVT, 4> ValueVTs;
150 ComputeValueVTs(TLI, PN->getType(), ValueVTs);
151 for (unsigned vti = 0, vte = ValueVTs.size(); vti != vte; ++vti) {
152 EVT VT = ValueVTs[vti];
153 unsigned NumRegisters = TLI.getNumRegisters(Fn->getContext(), VT);
154 const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
155 for (unsigned i = 0; i != NumRegisters; ++i)
156 BuildMI(MBB, DL, TII->get(TargetOpcode::PHI), PHIReg + i);
157 PHIReg += NumRegisters;
162 // Mark landing pad blocks.
163 for (BB = Fn->begin(); BB != EB; ++BB)
164 if (const InvokeInst *Invoke = dyn_cast<InvokeInst>(BB->getTerminator()))
165 MBBMap[Invoke->getSuccessor(1)]->setIsLandingPad();
168 /// clear - Clear out all the function-specific state. This returns this
169 /// FunctionLoweringInfo to an empty state, ready to be used for a
170 /// different function.
171 void FunctionLoweringInfo::clear() {
172 assert(CatchInfoFound.size() == CatchInfoLost.size() &&
173 "Not all catch info was assigned to a landing pad!");
177 StaticAllocaMap.clear();
179 CatchInfoLost.clear();
180 CatchInfoFound.clear();
182 LiveOutRegInfo.clear();
183 ArgDbgValues.clear();
187 /// CreateReg - Allocate a single virtual register for the given type.
188 unsigned FunctionLoweringInfo::CreateReg(EVT VT) {
189 return RegInfo->createVirtualRegister(TLI.getRegClassFor(VT));
192 /// CreateRegs - Allocate the appropriate number of virtual registers of
193 /// the correctly promoted or expanded types. Assign these registers
194 /// consecutive vreg numbers and return the first assigned number.
196 /// In the case that the given value has struct or array type, this function
197 /// will assign registers for each member or element.
199 unsigned FunctionLoweringInfo::CreateRegs(const Type *Ty) {
200 SmallVector<EVT, 4> ValueVTs;
201 ComputeValueVTs(TLI, Ty, ValueVTs);
203 unsigned FirstReg = 0;
204 for (unsigned Value = 0, e = ValueVTs.size(); Value != e; ++Value) {
205 EVT ValueVT = ValueVTs[Value];
206 EVT RegisterVT = TLI.getRegisterType(Ty->getContext(), ValueVT);
208 unsigned NumRegs = TLI.getNumRegisters(Ty->getContext(), ValueVT);
209 for (unsigned i = 0; i != NumRegs; ++i) {
210 unsigned R = CreateReg(RegisterVT);
211 if (!FirstReg) FirstReg = R;
217 /// AddCatchInfo - Extract the personality and type infos from an eh.selector
218 /// call, and add them to the specified machine basic block.
219 void llvm::AddCatchInfo(const CallInst &I, MachineModuleInfo *MMI,
220 MachineBasicBlock *MBB) {
221 // Inform the MachineModuleInfo of the personality for this landing pad.
222 const ConstantExpr *CE = cast<ConstantExpr>(I.getArgOperand(1));
223 assert(CE->getOpcode() == Instruction::BitCast &&
224 isa<Function>(CE->getOperand(0)) &&
225 "Personality should be a function");
226 MMI->addPersonality(MBB, cast<Function>(CE->getOperand(0)));
228 // Gather all the type infos for this landing pad and pass them along to
229 // MachineModuleInfo.
230 std::vector<const GlobalVariable *> TyInfo;
231 unsigned N = I.getNumArgOperands();
233 for (unsigned i = N - 1; i > 1; --i) {
234 if (const ConstantInt *CI = dyn_cast<ConstantInt>(I.getArgOperand(i))) {
235 unsigned FilterLength = CI->getZExtValue();
236 unsigned FirstCatch = i + FilterLength + !FilterLength;
237 assert(FirstCatch <= N && "Invalid filter length");
239 if (FirstCatch < N) {
240 TyInfo.reserve(N - FirstCatch);
241 for (unsigned j = FirstCatch; j < N; ++j)
242 TyInfo.push_back(ExtractTypeInfo(I.getArgOperand(j)));
243 MMI->addCatchTypeInfo(MBB, TyInfo);
249 MMI->addCleanup(MBB);
252 TyInfo.reserve(FilterLength - 1);
253 for (unsigned j = i + 1; j < FirstCatch; ++j)
254 TyInfo.push_back(ExtractTypeInfo(I.getArgOperand(j)));
255 MMI->addFilterTypeInfo(MBB, TyInfo);
264 TyInfo.reserve(N - 2);
265 for (unsigned j = 2; j < N; ++j)
266 TyInfo.push_back(ExtractTypeInfo(I.getArgOperand(j)));
267 MMI->addCatchTypeInfo(MBB, TyInfo);
271 void llvm::CopyCatchInfo(const BasicBlock *SrcBB, const BasicBlock *DestBB,
272 MachineModuleInfo *MMI, FunctionLoweringInfo &FLI) {
273 for (BasicBlock::const_iterator I = SrcBB->begin(), E = --SrcBB->end();
275 if (const EHSelectorInst *EHSel = dyn_cast<EHSelectorInst>(I)) {
276 // Apply the catch info to DestBB.
277 AddCatchInfo(*EHSel, MMI, FLI.MBBMap[DestBB]);
279 if (!FLI.MBBMap[SrcBB]->isLandingPad())
280 FLI.CatchInfoFound.insert(EHSel);