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();
50 if (cast<Instruction>(*UI)->getParent() != BB || isa<PHINode>(*UI))
55 /// isOnlyUsedInEntryBlock - If the specified argument is only used in the
56 /// entry block, return true. This includes arguments used by switches, since
57 /// the switch may expand into multiple basic blocks.
58 static bool isOnlyUsedInEntryBlock(const Argument *A, bool EnableFastISel) {
59 // With FastISel active, we may be splitting blocks, so force creation
60 // of virtual registers for all non-dead arguments.
62 return A->use_empty();
64 const BasicBlock *Entry = A->getParent()->begin();
65 for (Value::const_use_iterator UI = A->use_begin(), E = A->use_end();
67 if (cast<Instruction>(*UI)->getParent() != Entry || isa<SwitchInst>(*UI))
68 return false; // Use not in entry block.
72 FunctionLoweringInfo::FunctionLoweringInfo(const TargetLowering &tli)
76 void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf) {
79 RegInfo = &MF->getRegInfo();
81 // Check whether the function can return without sret-demotion.
82 SmallVector<ISD::OutputArg, 4> Outs;
83 GetReturnInfo(Fn->getReturnType(),
84 Fn->getAttributes().getRetAttributes(), Outs, TLI);
85 CanLowerReturn = TLI.CanLowerReturn(Fn->getCallingConv(), Fn->isVarArg(),
86 Outs, Fn->getContext());
88 // Create a vreg for each argument register that is not dead and is used
89 // outside of the entry block for the function.
90 for (Function::const_arg_iterator AI = Fn->arg_begin(), E = Fn->arg_end();
92 if (!isOnlyUsedInEntryBlock(AI, EnableFastISel))
93 InitializeRegForValue(AI);
95 // Initialize the mapping of values to registers. This is only set up for
96 // instruction values that are used outside of the block that defines
98 Function::const_iterator BB = Fn->begin(), EB = Fn->end();
99 for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I)
100 if (const AllocaInst *AI = dyn_cast<AllocaInst>(I))
101 if (const ConstantInt *CUI = dyn_cast<ConstantInt>(AI->getArraySize())) {
102 const Type *Ty = AI->getAllocatedType();
103 uint64_t TySize = TLI.getTargetData()->getTypeAllocSize(Ty);
105 std::max((unsigned)TLI.getTargetData()->getPrefTypeAlignment(Ty),
108 TySize *= CUI->getZExtValue(); // Get total allocated size.
109 if (TySize == 0) TySize = 1; // Don't create zero-sized stack objects.
110 StaticAllocaMap[AI] =
111 MF->getFrameInfo()->CreateStackObject(TySize, Align, false);
114 for (; BB != EB; ++BB)
115 for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I)
116 if (isUsedOutsideOfDefiningBlock(I))
117 if (!isa<AllocaInst>(I) ||
118 !StaticAllocaMap.count(cast<AllocaInst>(I)))
119 InitializeRegForValue(I);
121 // Create an initial MachineBasicBlock for each LLVM BasicBlock in F. This
122 // also creates the initial PHI MachineInstrs, though none of the input
123 // operands are populated.
124 for (BB = Fn->begin(); BB != EB; ++BB) {
125 MachineBasicBlock *MBB = mf.CreateMachineBasicBlock(BB);
129 // Transfer the address-taken flag. This is necessary because there could
130 // be multiple MachineBasicBlocks corresponding to one BasicBlock, and only
131 // the first one should be marked.
132 if (BB->hasAddressTaken())
133 MBB->setHasAddressTaken();
135 // Create Machine PHI nodes for LLVM PHI nodes, lowering them as
137 for (BasicBlock::const_iterator I = BB->begin();
138 const PHINode *PN = dyn_cast<PHINode>(I); ++I) {
139 if (PN->use_empty()) continue;
141 DebugLoc DL = PN->getDebugLoc();
142 unsigned PHIReg = ValueMap[PN];
143 assert(PHIReg && "PHI node does not have an assigned virtual register!");
145 SmallVector<EVT, 4> ValueVTs;
146 ComputeValueVTs(TLI, PN->getType(), ValueVTs);
147 for (unsigned vti = 0, vte = ValueVTs.size(); vti != vte; ++vti) {
148 EVT VT = ValueVTs[vti];
149 unsigned NumRegisters = TLI.getNumRegisters(Fn->getContext(), VT);
150 const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
151 for (unsigned i = 0; i != NumRegisters; ++i)
152 BuildMI(MBB, DL, TII->get(TargetOpcode::PHI), PHIReg + i);
153 PHIReg += NumRegisters;
158 // Mark landing pad blocks.
159 for (BB = Fn->begin(); BB != EB; ++BB)
160 if (const InvokeInst *Invoke = dyn_cast<InvokeInst>(BB->getTerminator()))
161 MBBMap[Invoke->getSuccessor(1)]->setIsLandingPad();
164 /// clear - Clear out all the function-specific state. This returns this
165 /// FunctionLoweringInfo to an empty state, ready to be used for a
166 /// different function.
167 void FunctionLoweringInfo::clear() {
168 assert(CatchInfoFound.size() == CatchInfoLost.size() &&
169 "Not all catch info was assigned to a landing pad!");
173 StaticAllocaMap.clear();
175 CatchInfoLost.clear();
176 CatchInfoFound.clear();
178 LiveOutRegInfo.clear();
179 ArgDbgValues.clear();
182 /// CreateReg - Allocate a single virtual register for the given type.
183 unsigned FunctionLoweringInfo::CreateReg(EVT VT) {
184 return RegInfo->createVirtualRegister(TLI.getRegClassFor(VT));
187 /// CreateRegs - Allocate the appropriate number of virtual registers of
188 /// the correctly promoted or expanded types. Assign these registers
189 /// consecutive vreg numbers and return the first assigned number.
191 /// In the case that the given value has struct or array type, this function
192 /// will assign registers for each member or element.
194 unsigned FunctionLoweringInfo::CreateRegs(const Type *Ty) {
195 SmallVector<EVT, 4> ValueVTs;
196 ComputeValueVTs(TLI, Ty, ValueVTs);
198 unsigned FirstReg = 0;
199 for (unsigned Value = 0, e = ValueVTs.size(); Value != e; ++Value) {
200 EVT ValueVT = ValueVTs[Value];
201 EVT RegisterVT = TLI.getRegisterType(Ty->getContext(), ValueVT);
203 unsigned NumRegs = TLI.getNumRegisters(Ty->getContext(), ValueVT);
204 for (unsigned i = 0; i != NumRegs; ++i) {
205 unsigned R = CreateReg(RegisterVT);
206 if (!FirstReg) FirstReg = R;
212 /// AddCatchInfo - Extract the personality and type infos from an eh.selector
213 /// call, and add them to the specified machine basic block.
214 void llvm::AddCatchInfo(const CallInst &I, MachineModuleInfo *MMI,
215 MachineBasicBlock *MBB) {
216 // Inform the MachineModuleInfo of the personality for this landing pad.
217 const ConstantExpr *CE = cast<ConstantExpr>(I.getArgOperand(1));
218 assert(CE->getOpcode() == Instruction::BitCast &&
219 isa<Function>(CE->getOperand(0)) &&
220 "Personality should be a function");
221 MMI->addPersonality(MBB, cast<Function>(CE->getOperand(0)));
223 // Gather all the type infos for this landing pad and pass them along to
224 // MachineModuleInfo.
225 std::vector<const GlobalVariable *> TyInfo;
226 unsigned N = I.getNumArgOperands();
228 for (unsigned i = N - 1; i > 1; --i) {
229 if (const ConstantInt *CI = dyn_cast<ConstantInt>(I.getArgOperand(i))) {
230 unsigned FilterLength = CI->getZExtValue();
231 unsigned FirstCatch = i + FilterLength + !FilterLength;
232 assert(FirstCatch <= N && "Invalid filter length");
234 if (FirstCatch < N) {
235 TyInfo.reserve(N - FirstCatch);
236 for (unsigned j = FirstCatch; j < N; ++j)
237 TyInfo.push_back(ExtractTypeInfo(I.getArgOperand(j)));
238 MMI->addCatchTypeInfo(MBB, TyInfo);
244 MMI->addCleanup(MBB);
247 TyInfo.reserve(FilterLength - 1);
248 for (unsigned j = i + 1; j < FirstCatch; ++j)
249 TyInfo.push_back(ExtractTypeInfo(I.getArgOperand(j)));
250 MMI->addFilterTypeInfo(MBB, TyInfo);
259 TyInfo.reserve(N - 2);
260 for (unsigned j = 2; j < N; ++j)
261 TyInfo.push_back(ExtractTypeInfo(I.getArgOperand(j)));
262 MMI->addCatchTypeInfo(MBB, TyInfo);
266 void llvm::CopyCatchInfo(const BasicBlock *SrcBB, const BasicBlock *DestBB,
267 MachineModuleInfo *MMI, FunctionLoweringInfo &FLI) {
268 for (BasicBlock::const_iterator I = SrcBB->begin(), E = --SrcBB->end();
270 if (const EHSelectorInst *EHSel = dyn_cast<EHSelectorInst>(I)) {
271 // Apply the catch info to DestBB.
272 AddCatchInfo(*EHSel, MMI, FLI.MBBMap[DestBB]);
274 if (!FLI.MBBMap[SrcBB]->isLandingPad())
275 FLI.CatchInfoFound.insert(EHSel);