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 "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/TargetIntrinsicInfo.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();
51 if (cast<Instruction>(*UI)->getParent() != BB || isa<PHINode>(*UI))
56 /// isOnlyUsedInEntryBlock - If the specified argument is only used in the
57 /// entry block, return true. This includes arguments used by switches, since
58 /// the switch may expand into multiple basic blocks.
59 static bool isOnlyUsedInEntryBlock(const Argument *A, bool EnableFastISel) {
60 // With FastISel active, we may be splitting blocks, so force creation
61 // of virtual registers for all non-dead arguments.
63 return A->use_empty();
65 const BasicBlock *Entry = A->getParent()->begin();
66 for (Value::const_use_iterator UI = A->use_begin(), E = A->use_end();
68 if (cast<Instruction>(*UI)->getParent() != Entry || isa<SwitchInst>(*UI))
69 return false; // Use not in entry block.
73 FunctionLoweringInfo::FunctionLoweringInfo(const TargetLowering &tli)
77 void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf) {
80 RegInfo = &MF->getRegInfo();
82 // Create a vreg for each argument register that is not dead and is used
83 // outside of the entry block for the function.
84 for (Function::const_arg_iterator AI = Fn->arg_begin(), E = Fn->arg_end();
86 if (!isOnlyUsedInEntryBlock(AI, EnableFastISel))
87 InitializeRegForValue(AI);
89 // Initialize the mapping of values to registers. This is only set up for
90 // instruction values that are used outside of the block that defines
92 Function::const_iterator BB = Fn->begin(), EB = Fn->end();
93 for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I)
94 if (const AllocaInst *AI = dyn_cast<AllocaInst>(I))
95 if (const ConstantInt *CUI = dyn_cast<ConstantInt>(AI->getArraySize())) {
96 const Type *Ty = AI->getAllocatedType();
97 uint64_t TySize = TLI.getTargetData()->getTypeAllocSize(Ty);
99 std::max((unsigned)TLI.getTargetData()->getPrefTypeAlignment(Ty),
102 TySize *= CUI->getZExtValue(); // Get total allocated size.
103 if (TySize == 0) TySize = 1; // Don't create zero-sized stack objects.
104 StaticAllocaMap[AI] =
105 MF->getFrameInfo()->CreateStackObject(TySize, Align, false);
108 for (; BB != EB; ++BB)
109 for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I)
110 if (isUsedOutsideOfDefiningBlock(I))
111 if (!isa<AllocaInst>(I) ||
112 !StaticAllocaMap.count(cast<AllocaInst>(I)))
113 InitializeRegForValue(I);
115 // Create an initial MachineBasicBlock for each LLVM BasicBlock in F. This
116 // also creates the initial PHI MachineInstrs, though none of the input
117 // operands are populated.
118 for (BB = Fn->begin(); BB != EB; ++BB) {
119 MachineBasicBlock *MBB = mf.CreateMachineBasicBlock(BB);
123 // Transfer the address-taken flag. This is necessary because there could
124 // be multiple MachineBasicBlocks corresponding to one BasicBlock, and only
125 // the first one should be marked.
126 if (BB->hasAddressTaken())
127 MBB->setHasAddressTaken();
129 // Create Machine PHI nodes for LLVM PHI nodes, lowering them as
131 for (BasicBlock::const_iterator I = BB->begin();
132 const PHINode *PN = dyn_cast<PHINode>(I); ++I) {
133 if (PN->use_empty()) continue;
135 DebugLoc DL = PN->getDebugLoc();
136 unsigned PHIReg = ValueMap[PN];
137 assert(PHIReg && "PHI node does not have an assigned virtual register!");
139 SmallVector<EVT, 4> ValueVTs;
140 ComputeValueVTs(TLI, PN->getType(), ValueVTs);
141 for (unsigned vti = 0, vte = ValueVTs.size(); vti != vte; ++vti) {
142 EVT VT = ValueVTs[vti];
143 unsigned NumRegisters = TLI.getNumRegisters(Fn->getContext(), VT);
144 const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
145 for (unsigned i = 0; i != NumRegisters; ++i)
146 BuildMI(MBB, DL, TII->get(TargetOpcode::PHI), PHIReg + i);
147 PHIReg += NumRegisters;
152 // Mark landing pad blocks.
153 for (BB = Fn->begin(); BB != EB; ++BB)
154 if (const InvokeInst *Invoke = dyn_cast<InvokeInst>(BB->getTerminator()))
155 MBBMap[Invoke->getSuccessor(1)]->setIsLandingPad();
158 /// clear - Clear out all the function-specific state. This returns this
159 /// FunctionLoweringInfo to an empty state, ready to be used for a
160 /// different function.
161 void FunctionLoweringInfo::clear() {
162 assert(CatchInfoFound.size() == CatchInfoLost.size() &&
163 "Not all catch info was assigned to a landing pad!");
167 StaticAllocaMap.clear();
169 CatchInfoLost.clear();
170 CatchInfoFound.clear();
172 LiveOutRegInfo.clear();
173 ArgDbgValues.clear();
176 unsigned FunctionLoweringInfo::MakeReg(EVT VT) {
177 return RegInfo->createVirtualRegister(TLI.getRegClassFor(VT));
180 /// CreateRegForValue - Allocate the appropriate number of virtual registers of
181 /// the correctly promoted or expanded types. Assign these registers
182 /// consecutive vreg numbers and return the first assigned number.
184 /// In the case that the given value has struct or array type, this function
185 /// will assign registers for each member or element.
187 unsigned FunctionLoweringInfo::CreateRegForValue(const Value *V) {
188 SmallVector<EVT, 4> ValueVTs;
189 ComputeValueVTs(TLI, V->getType(), ValueVTs);
191 unsigned FirstReg = 0;
192 for (unsigned Value = 0, e = ValueVTs.size(); Value != e; ++Value) {
193 EVT ValueVT = ValueVTs[Value];
194 EVT RegisterVT = TLI.getRegisterType(V->getContext(), ValueVT);
196 unsigned NumRegs = TLI.getNumRegisters(V->getContext(), ValueVT);
197 for (unsigned i = 0; i != NumRegs; ++i) {
198 unsigned R = MakeReg(RegisterVT);
199 if (!FirstReg) FirstReg = R;
205 /// AddCatchInfo - Extract the personality and type infos from an eh.selector
206 /// call, and add them to the specified machine basic block.
207 void llvm::AddCatchInfo(const CallInst &I, MachineModuleInfo *MMI,
208 MachineBasicBlock *MBB) {
209 // Inform the MachineModuleInfo of the personality for this landing pad.
210 const ConstantExpr *CE = cast<ConstantExpr>(I.getOperand(2));
211 assert(CE->getOpcode() == Instruction::BitCast &&
212 isa<Function>(CE->getOperand(0)) &&
213 "Personality should be a function");
214 MMI->addPersonality(MBB, cast<Function>(CE->getOperand(0)));
216 // Gather all the type infos for this landing pad and pass them along to
217 // MachineModuleInfo.
218 std::vector<const GlobalVariable *> TyInfo;
219 unsigned N = I.getNumOperands();
221 for (unsigned i = N - 1; i > 2; --i) {
222 if (const ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand(i))) {
223 unsigned FilterLength = CI->getZExtValue();
224 unsigned FirstCatch = i + FilterLength + !FilterLength;
225 assert (FirstCatch <= N && "Invalid filter length");
227 if (FirstCatch < N) {
228 TyInfo.reserve(N - FirstCatch);
229 for (unsigned j = FirstCatch; j < N; ++j)
230 TyInfo.push_back(ExtractTypeInfo(I.getOperand(j)));
231 MMI->addCatchTypeInfo(MBB, TyInfo);
237 MMI->addCleanup(MBB);
240 TyInfo.reserve(FilterLength - 1);
241 for (unsigned j = i + 1; j < FirstCatch; ++j)
242 TyInfo.push_back(ExtractTypeInfo(I.getOperand(j)));
243 MMI->addFilterTypeInfo(MBB, TyInfo);
252 TyInfo.reserve(N - 3);
253 for (unsigned j = 3; j < N; ++j)
254 TyInfo.push_back(ExtractTypeInfo(I.getOperand(j)));
255 MMI->addCatchTypeInfo(MBB, TyInfo);
259 void llvm::CopyCatchInfo(const BasicBlock *SrcBB, const BasicBlock *DestBB,
260 MachineModuleInfo *MMI, FunctionLoweringInfo &FLI) {
261 for (BasicBlock::const_iterator I = SrcBB->begin(), E = --SrcBB->end();
263 if (const EHSelectorInst *EHSel = dyn_cast<EHSelectorInst>(I)) {
264 // Apply the catch info to DestBB.
265 AddCatchInfo(*EHSel, MMI, FLI.MBBMap[DestBB]);
267 if (!FLI.MBBMap[SrcBB]->isLandingPad())
268 FLI.CatchInfoFound.insert(EHSel);