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.
62 // Don't force virtual registers for byval arguments though, because
63 // fast-isel can't handle those in all cases.
64 if (EnableFastISel && !A->hasByValAttr())
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();
70 if (cast<Instruction>(*UI)->getParent() != Entry || isa<SwitchInst>(*UI))
71 return false; // Use not in entry block.
75 FunctionLoweringInfo::FunctionLoweringInfo(const TargetLowering &tli)
79 void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf,
80 bool EnableFastISel) {
83 RegInfo = &MF->getRegInfo();
85 // Create a vreg for each argument register that is not dead and is used
86 // outside of the entry block for the function.
87 for (Function::const_arg_iterator AI = Fn->arg_begin(), E = Fn->arg_end();
89 if (!isOnlyUsedInEntryBlock(AI, EnableFastISel))
90 InitializeRegForValue(AI);
92 // Initialize the mapping of values to registers. This is only set up for
93 // instruction values that are used outside of the block that defines
95 Function::const_iterator BB = Fn->begin(), EB = Fn->end();
96 for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I)
97 if (const AllocaInst *AI = dyn_cast<AllocaInst>(I))
98 if (const ConstantInt *CUI = dyn_cast<ConstantInt>(AI->getArraySize())) {
99 const Type *Ty = AI->getAllocatedType();
100 uint64_t TySize = TLI.getTargetData()->getTypeAllocSize(Ty);
102 std::max((unsigned)TLI.getTargetData()->getPrefTypeAlignment(Ty),
105 TySize *= CUI->getZExtValue(); // Get total allocated size.
106 if (TySize == 0) TySize = 1; // Don't create zero-sized stack objects.
107 StaticAllocaMap[AI] =
108 MF->getFrameInfo()->CreateStackObject(TySize, Align, false);
111 for (; BB != EB; ++BB)
112 for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I)
113 if (isUsedOutsideOfDefiningBlock(I))
114 if (!isa<AllocaInst>(I) ||
115 !StaticAllocaMap.count(cast<AllocaInst>(I)))
116 InitializeRegForValue(I);
118 // Create an initial MachineBasicBlock for each LLVM BasicBlock in F. This
119 // also creates the initial PHI MachineInstrs, though none of the input
120 // operands are populated.
121 for (BB = Fn->begin(); BB != EB; ++BB) {
122 MachineBasicBlock *MBB = mf.CreateMachineBasicBlock(BB);
126 // Transfer the address-taken flag. This is necessary because there could
127 // be multiple MachineBasicBlocks corresponding to one BasicBlock, and only
128 // the first one should be marked.
129 if (BB->hasAddressTaken())
130 MBB->setHasAddressTaken();
132 // Create Machine PHI nodes for LLVM PHI nodes, lowering them as
134 for (BasicBlock::const_iterator I = BB->begin();
135 const PHINode *PN = dyn_cast<PHINode>(I); ++I) {
136 if (PN->use_empty()) continue;
138 DebugLoc DL = PN->getDebugLoc();
139 unsigned PHIReg = ValueMap[PN];
140 assert(PHIReg && "PHI node does not have an assigned virtual register!");
142 SmallVector<EVT, 4> ValueVTs;
143 ComputeValueVTs(TLI, PN->getType(), ValueVTs);
144 for (unsigned vti = 0, vte = ValueVTs.size(); vti != vte; ++vti) {
145 EVT VT = ValueVTs[vti];
146 unsigned NumRegisters = TLI.getNumRegisters(Fn->getContext(), VT);
147 const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
148 for (unsigned i = 0; i != NumRegisters; ++i)
149 BuildMI(MBB, DL, TII->get(TargetOpcode::PHI), PHIReg + i);
150 PHIReg += NumRegisters;
155 // Mark landing pad blocks.
156 for (BB = Fn->begin(); BB != EB; ++BB)
157 if (const InvokeInst *Invoke = dyn_cast<InvokeInst>(BB->getTerminator()))
158 MBBMap[Invoke->getSuccessor(1)]->setIsLandingPad();
161 /// clear - Clear out all the function-specific state. This returns this
162 /// FunctionLoweringInfo to an empty state, ready to be used for a
163 /// different function.
164 void FunctionLoweringInfo::clear() {
165 assert(CatchInfoFound.size() == CatchInfoLost.size() &&
166 "Not all catch info was assigned to a landing pad!");
170 StaticAllocaMap.clear();
172 CatchInfoLost.clear();
173 CatchInfoFound.clear();
175 LiveOutRegInfo.clear();
178 unsigned FunctionLoweringInfo::MakeReg(EVT VT) {
179 return RegInfo->createVirtualRegister(TLI.getRegClassFor(VT));
182 /// CreateRegForValue - Allocate the appropriate number of virtual registers of
183 /// the correctly promoted or expanded types. Assign these registers
184 /// consecutive vreg numbers and return the first assigned number.
186 /// In the case that the given value has struct or array type, this function
187 /// will assign registers for each member or element.
189 unsigned FunctionLoweringInfo::CreateRegForValue(const Value *V) {
190 SmallVector<EVT, 4> ValueVTs;
191 ComputeValueVTs(TLI, V->getType(), ValueVTs);
193 unsigned FirstReg = 0;
194 for (unsigned Value = 0, e = ValueVTs.size(); Value != e; ++Value) {
195 EVT ValueVT = ValueVTs[Value];
196 EVT RegisterVT = TLI.getRegisterType(V->getContext(), ValueVT);
198 unsigned NumRegs = TLI.getNumRegisters(V->getContext(), ValueVT);
199 for (unsigned i = 0; i != NumRegs; ++i) {
200 unsigned R = MakeReg(RegisterVT);
201 if (!FirstReg) FirstReg = R;
207 /// AddCatchInfo - Extract the personality and type infos from an eh.selector
208 /// call, and add them to the specified machine basic block.
209 void llvm::AddCatchInfo(const CallInst &I, MachineModuleInfo *MMI,
210 MachineBasicBlock *MBB) {
211 // Inform the MachineModuleInfo of the personality for this landing pad.
212 const ConstantExpr *CE = cast<ConstantExpr>(I.getOperand(2));
213 assert(CE->getOpcode() == Instruction::BitCast &&
214 isa<Function>(CE->getOperand(0)) &&
215 "Personality should be a function");
216 MMI->addPersonality(MBB, cast<Function>(CE->getOperand(0)));
218 // Gather all the type infos for this landing pad and pass them along to
219 // MachineModuleInfo.
220 std::vector<const GlobalVariable *> TyInfo;
221 unsigned N = I.getNumOperands();
223 for (unsigned i = N - 1; i > 2; --i) {
224 if (const ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand(i))) {
225 unsigned FilterLength = CI->getZExtValue();
226 unsigned FirstCatch = i + FilterLength + !FilterLength;
227 assert (FirstCatch <= N && "Invalid filter length");
229 if (FirstCatch < N) {
230 TyInfo.reserve(N - FirstCatch);
231 for (unsigned j = FirstCatch; j < N; ++j)
232 TyInfo.push_back(ExtractTypeInfo(I.getOperand(j)));
233 MMI->addCatchTypeInfo(MBB, TyInfo);
239 MMI->addCleanup(MBB);
242 TyInfo.reserve(FilterLength - 1);
243 for (unsigned j = i + 1; j < FirstCatch; ++j)
244 TyInfo.push_back(ExtractTypeInfo(I.getOperand(j)));
245 MMI->addFilterTypeInfo(MBB, TyInfo);
254 TyInfo.reserve(N - 3);
255 for (unsigned j = 3; j < N; ++j)
256 TyInfo.push_back(ExtractTypeInfo(I.getOperand(j)));
257 MMI->addCatchTypeInfo(MBB, TyInfo);
261 void llvm::CopyCatchInfo(const BasicBlock *SrcBB, const BasicBlock *DestBB,
262 MachineModuleInfo *MMI, FunctionLoweringInfo &FLI) {
263 for (BasicBlock::const_iterator I = SrcBB->begin(), E = --SrcBB->end();
265 if (const EHSelectorInst *EHSel = dyn_cast<EHSelectorInst>(I)) {
266 // Apply the catch info to DestBB.
267 AddCatchInfo(*EHSel, MMI, FLI.MBBMap[DestBB]);
269 if (!FLI.MBBMap[SrcBB]->isLandingPad())
270 FLI.CatchInfoFound.insert(EHSel);