1 //===-- SelectionDAGBuilder.h - Selection-DAG building --------------------===//
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 from LLVM IR into SelectionDAG IR.
12 //===----------------------------------------------------------------------===//
14 #ifndef SELECTIONDAGBUILDER_H
15 #define SELECTIONDAGBUILDER_H
17 #include "llvm/Constants.h"
18 #include "llvm/CodeGen/SelectionDAG.h"
19 #include "llvm/ADT/APInt.h"
20 #include "llvm/ADT/DenseMap.h"
21 #include "llvm/CodeGen/SelectionDAGNodes.h"
22 #include "llvm/CodeGen/ValueTypes.h"
23 #include "llvm/Support/CallSite.h"
24 #include "llvm/Support/ErrorHandling.h"
36 class ExtractElementInst;
37 class ExtractValueInst;
44 class FunctionLoweringInfo;
45 class GetElementPtrInst;
51 class InsertElementInst;
52 class InsertValueInst;
55 class MachineBasicBlock;
57 class MachineRegisterInfo;
65 class ShuffleVectorInst;
73 class UnreachableInst;
78 //===----------------------------------------------------------------------===//
79 /// SelectionDAGBuilder - This is the common target-independent lowering
80 /// implementation that is parameterized by a TargetLowering object.
82 class SelectionDAGBuilder {
83 /// CurDebugLoc - current file + line number. Changes as we build the DAG.
86 DenseMap<const Value*, SDValue> NodeMap;
88 /// UnusedArgNodeMap - Maps argument value for unused arguments. This is used
89 /// to preserve debug information for incoming arguments.
90 DenseMap<const Value*, SDValue> UnusedArgNodeMap;
92 /// DanglingDebugInfo - Helper type for DanglingDebugInfoMap.
93 class DanglingDebugInfo {
94 const DbgValueInst* DI;
98 DanglingDebugInfo() : DI(0), dl(DebugLoc()), SDNodeOrder(0) { }
99 DanglingDebugInfo(const DbgValueInst *di, DebugLoc DL, unsigned SDNO) :
100 DI(di), dl(DL), SDNodeOrder(SDNO) { }
101 const DbgValueInst* getDI() { return DI; }
102 DebugLoc getdl() { return dl; }
103 unsigned getSDNodeOrder() { return SDNodeOrder; }
106 /// DanglingDebugInfoMap - Keeps track of dbg_values for which we have not
107 /// yet seen the referent. We defer handling these until we do see it.
108 DenseMap<const Value*, DanglingDebugInfo> DanglingDebugInfoMap;
111 /// PendingLoads - Loads are not emitted to the program immediately. We bunch
112 /// them up and then emit token factor nodes when possible. This allows us to
113 /// get simple disambiguation between loads without worrying about alias
115 SmallVector<SDValue, 8> PendingLoads;
118 /// PendingExports - CopyToReg nodes that copy values to virtual registers
119 /// for export to other blocks need to be emitted before any terminator
120 /// instruction, but they have no other ordering requirements. We bunch them
121 /// up and the emit a single tokenfactor for them just before terminator
123 SmallVector<SDValue, 8> PendingExports;
125 /// SDNodeOrder - A unique monotonically increasing number used to order the
126 /// SDNodes we create.
127 unsigned SDNodeOrder;
129 /// Case - A struct to record the Value for a switch case, and the
130 /// case's target basic block.
134 MachineBasicBlock* BB;
136 Case() : Low(0), High(0), BB(0) { }
137 Case(Constant* low, Constant* high, MachineBasicBlock* bb) :
138 Low(low), High(high), BB(bb) { }
140 const APInt &rHigh = cast<ConstantInt>(High)->getValue();
141 const APInt &rLow = cast<ConstantInt>(Low)->getValue();
142 return (rHigh - rLow + 1ULL);
148 MachineBasicBlock* BB;
151 CaseBits(uint64_t mask, MachineBasicBlock* bb, unsigned bits):
152 Mask(mask), BB(bb), Bits(bits) { }
155 typedef std::vector<Case> CaseVector;
156 typedef std::vector<CaseBits> CaseBitsVector;
157 typedef CaseVector::iterator CaseItr;
158 typedef std::pair<CaseItr, CaseItr> CaseRange;
160 /// CaseRec - A struct with ctor used in lowering switches to a binary tree
161 /// of conditional branches.
163 CaseRec(MachineBasicBlock *bb, const Constant *lt, const Constant *ge,
165 CaseBB(bb), LT(lt), GE(ge), Range(r) {}
167 /// CaseBB - The MBB in which to emit the compare and branch
168 MachineBasicBlock *CaseBB;
169 /// LT, GE - If nonzero, we know the current case value must be less-than or
170 /// greater-than-or-equal-to these Constants.
173 /// Range - A pair of iterators representing the range of case values to be
174 /// processed at this point in the binary search tree.
178 typedef std::vector<CaseRec> CaseRecVector;
180 /// The comparison function for sorting the switch case values in the vector.
181 /// WARNING: Case ranges should be disjoint!
183 bool operator()(const Case &C1, const Case &C2) {
184 assert(isa<ConstantInt>(C1.Low) && isa<ConstantInt>(C2.High));
185 const ConstantInt* CI1 = cast<const ConstantInt>(C1.Low);
186 const ConstantInt* CI2 = cast<const ConstantInt>(C2.High);
187 return CI1->getValue().slt(CI2->getValue());
192 bool operator()(const CaseBits &C1, const CaseBits &C2) {
193 return C1.Bits > C2.Bits;
197 size_t Clusterify(CaseVector &Cases, const SwitchInst &SI);
199 /// CaseBlock - This structure is used to communicate between
200 /// SelectionDAGBuilder and SDISel for the code generation of additional basic
201 /// blocks needed by multi-case switch statements.
203 CaseBlock(ISD::CondCode cc, const Value *cmplhs, const Value *cmprhs,
204 const Value *cmpmiddle,
205 MachineBasicBlock *truebb, MachineBasicBlock *falsebb,
206 MachineBasicBlock *me)
207 : CC(cc), CmpLHS(cmplhs), CmpMHS(cmpmiddle), CmpRHS(cmprhs),
208 TrueBB(truebb), FalseBB(falsebb), ThisBB(me) {}
209 // CC - the condition code to use for the case block's setcc node
211 // CmpLHS/CmpRHS/CmpMHS - The LHS/MHS/RHS of the comparison to emit.
212 // Emit by default LHS op RHS. MHS is used for range comparisons:
213 // If MHS is not null: (LHS <= MHS) and (MHS <= RHS).
214 const Value *CmpLHS, *CmpMHS, *CmpRHS;
215 // TrueBB/FalseBB - the block to branch to if the setcc is true/false.
216 MachineBasicBlock *TrueBB, *FalseBB;
217 // ThisBB - the block into which to emit the code for the setcc and branches
218 MachineBasicBlock *ThisBB;
221 JumpTable(unsigned R, unsigned J, MachineBasicBlock *M,
222 MachineBasicBlock *D): Reg(R), JTI(J), MBB(M), Default(D) {}
224 /// Reg - the virtual register containing the index of the jump table entry
227 /// JTI - the JumpTableIndex for this jump table in the function.
229 /// MBB - the MBB into which to emit the code for the indirect jump.
230 MachineBasicBlock *MBB;
231 /// Default - the MBB of the default bb, which is a successor of the range
232 /// check MBB. This is when updating PHI nodes in successors.
233 MachineBasicBlock *Default;
235 struct JumpTableHeader {
236 JumpTableHeader(APInt F, APInt L, const Value *SV, MachineBasicBlock *H,
238 First(F), Last(L), SValue(SV), HeaderBB(H), Emitted(E) {}
242 MachineBasicBlock *HeaderBB;
245 typedef std::pair<JumpTableHeader, JumpTable> JumpTableBlock;
248 BitTestCase(uint64_t M, MachineBasicBlock* T, MachineBasicBlock* Tr):
249 Mask(M), ThisBB(T), TargetBB(Tr) { }
251 MachineBasicBlock *ThisBB;
252 MachineBasicBlock *TargetBB;
255 typedef SmallVector<BitTestCase, 3> BitTestInfo;
257 struct BitTestBlock {
258 BitTestBlock(APInt F, APInt R, const Value* SV,
259 unsigned Rg, EVT RgVT, bool E,
260 MachineBasicBlock* P, MachineBasicBlock* D,
261 const BitTestInfo& C):
262 First(F), Range(R), SValue(SV), Reg(Rg), RegVT(RgVT), Emitted(E),
263 Parent(P), Default(D), Cases(C) { }
270 MachineBasicBlock *Parent;
271 MachineBasicBlock *Default;
276 // TLI - This is information that describes the available target features we
277 // need for lowering. This indicates when operations are unavailable,
278 // implemented with a libcall, etc.
279 const TargetMachine &TM;
280 const TargetLowering &TLI;
282 const TargetData *TD;
285 /// SwitchCases - Vector of CaseBlock structures used to communicate
286 /// SwitchInst code generation information.
287 std::vector<CaseBlock> SwitchCases;
288 /// JTCases - Vector of JumpTable structures used to communicate
289 /// SwitchInst code generation information.
290 std::vector<JumpTableBlock> JTCases;
291 /// BitTestCases - Vector of BitTestBlock structures used to communicate
292 /// SwitchInst code generation information.
293 std::vector<BitTestBlock> BitTestCases;
295 // Emit PHI-node-operand constants only once even if used by multiple
297 DenseMap<const Constant *, unsigned> ConstantsOut;
299 /// FuncInfo - Information about the function as a whole.
301 FunctionLoweringInfo &FuncInfo;
303 /// OptLevel - What optimization level we're generating code for.
305 CodeGenOpt::Level OptLevel;
307 /// GFI - Garbage collection metadata for the function.
310 /// HasTailCall - This is set to true if a call in the current
311 /// block has been translated as a tail call. In this case,
312 /// no subsequent DAG nodes should be created.
316 LLVMContext *Context;
318 SelectionDAGBuilder(SelectionDAG &dag, FunctionLoweringInfo &funcinfo,
319 CodeGenOpt::Level ol)
320 : SDNodeOrder(0), TM(dag.getTarget()), TLI(dag.getTargetLoweringInfo()),
321 DAG(dag), FuncInfo(funcinfo), OptLevel(ol),
322 HasTailCall(false), Context(dag.getContext()) {
325 void init(GCFunctionInfo *gfi, AliasAnalysis &aa);
327 /// clear - Clear out the current SelectionDAG and the associated
328 /// state and prepare this SelectionDAGBuilder object to be used
329 /// for a new block. This doesn't clear out information about
330 /// additional blocks that are needed to complete switch lowering
331 /// or PHI node updating; that information is cleared out as it is
335 /// getRoot - Return the current virtual root of the Selection DAG,
336 /// flushing any PendingLoad items. This must be done before emitting
337 /// a store or any other node that may need to be ordered after any
338 /// prior load instructions.
342 /// getControlRoot - Similar to getRoot, but instead of flushing all the
343 /// PendingLoad items, flush all the PendingExports items. It is necessary
344 /// to do this before emitting a terminator instruction.
346 SDValue getControlRoot();
348 DebugLoc getCurDebugLoc() const { return CurDebugLoc; }
350 unsigned getSDNodeOrder() const { return SDNodeOrder; }
352 void CopyValueToVirtualRegister(const Value *V, unsigned Reg);
354 /// AssignOrderingToNode - Assign an ordering to the node. The order is gotten
355 /// from how the code appeared in the source. The ordering is used by the
356 /// scheduler to effectively turn off scheduling.
357 void AssignOrderingToNode(const SDNode *Node);
359 void visit(const Instruction &I);
361 void visit(unsigned Opcode, const User &I);
363 // resolveDanglingDebugInfo - if we saw an earlier dbg_value referring to V,
364 // generate the debug data structures now that we've seen its definition.
365 void resolveDanglingDebugInfo(const Value *V, SDValue Val);
366 SDValue getValue(const Value *V);
367 SDValue getNonRegisterValue(const Value *V);
368 SDValue getValueImpl(const Value *V);
370 void setValue(const Value *V, SDValue NewN) {
371 SDValue &N = NodeMap[V];
372 assert(N.getNode() == 0 && "Already set a value for this node!");
376 void setUnusedArgValue(const Value *V, SDValue NewN) {
377 SDValue &N = UnusedArgNodeMap[V];
378 assert(N.getNode() == 0 && "Already set a value for this node!");
382 void FindMergedConditions(const Value *Cond, MachineBasicBlock *TBB,
383 MachineBasicBlock *FBB, MachineBasicBlock *CurBB,
384 MachineBasicBlock *SwitchBB, unsigned Opc);
385 void EmitBranchForMergedCondition(const Value *Cond, MachineBasicBlock *TBB,
386 MachineBasicBlock *FBB,
387 MachineBasicBlock *CurBB,
388 MachineBasicBlock *SwitchBB);
389 bool ShouldEmitAsBranches(const std::vector<CaseBlock> &Cases);
390 bool isExportableFromCurrentBlock(const Value *V, const BasicBlock *FromBB);
391 void CopyToExportRegsIfNeeded(const Value *V);
392 void ExportFromCurrentBlock(const Value *V);
393 void LowerCallTo(ImmutableCallSite CS, SDValue Callee, bool IsTailCall,
394 MachineBasicBlock *LandingPad = NULL);
396 /// UpdateSplitBlock - When an MBB was split during scheduling, update the
397 /// references that ned to refer to the last resulting block.
398 void UpdateSplitBlock(MachineBasicBlock *First, MachineBasicBlock *Last);
401 // Terminator instructions.
402 void visitRet(const ReturnInst &I);
403 void visitBr(const BranchInst &I);
404 void visitSwitch(const SwitchInst &I);
405 void visitIndirectBr(const IndirectBrInst &I);
406 void visitUnreachable(const UnreachableInst &I) { /* noop */ }
408 // Helpers for visitSwitch
409 bool handleSmallSwitchRange(CaseRec& CR,
410 CaseRecVector& WorkList,
412 MachineBasicBlock* Default,
413 MachineBasicBlock *SwitchBB);
414 bool handleJTSwitchCase(CaseRec& CR,
415 CaseRecVector& WorkList,
417 MachineBasicBlock* Default,
418 MachineBasicBlock *SwitchBB);
419 bool handleBTSplitSwitchCase(CaseRec& CR,
420 CaseRecVector& WorkList,
422 MachineBasicBlock* Default,
423 MachineBasicBlock *SwitchBB);
424 bool handleBitTestsSwitchCase(CaseRec& CR,
425 CaseRecVector& WorkList,
427 MachineBasicBlock* Default,
428 MachineBasicBlock *SwitchBB);
430 void visitSwitchCase(CaseBlock &CB,
431 MachineBasicBlock *SwitchBB);
432 void visitBitTestHeader(BitTestBlock &B, MachineBasicBlock *SwitchBB);
433 void visitBitTestCase(BitTestBlock &BB,
434 MachineBasicBlock* NextMBB,
437 MachineBasicBlock *SwitchBB);
438 void visitJumpTable(JumpTable &JT);
439 void visitJumpTableHeader(JumpTable &JT, JumpTableHeader &JTH,
440 MachineBasicBlock *SwitchBB);
443 // These all get lowered before this pass.
444 void visitInvoke(const InvokeInst &I);
445 void visitUnwind(const UnwindInst &I);
447 void visitBinary(const User &I, unsigned OpCode);
448 void visitShift(const User &I, unsigned Opcode);
449 void visitAdd(const User &I) { visitBinary(I, ISD::ADD); }
450 void visitFAdd(const User &I) { visitBinary(I, ISD::FADD); }
451 void visitSub(const User &I) { visitBinary(I, ISD::SUB); }
452 void visitFSub(const User &I);
453 void visitMul(const User &I) { visitBinary(I, ISD::MUL); }
454 void visitFMul(const User &I) { visitBinary(I, ISD::FMUL); }
455 void visitURem(const User &I) { visitBinary(I, ISD::UREM); }
456 void visitSRem(const User &I) { visitBinary(I, ISD::SREM); }
457 void visitFRem(const User &I) { visitBinary(I, ISD::FREM); }
458 void visitUDiv(const User &I) { visitBinary(I, ISD::UDIV); }
459 void visitSDiv(const User &I) { visitBinary(I, ISD::SDIV); }
460 void visitFDiv(const User &I) { visitBinary(I, ISD::FDIV); }
461 void visitAnd (const User &I) { visitBinary(I, ISD::AND); }
462 void visitOr (const User &I) { visitBinary(I, ISD::OR); }
463 void visitXor (const User &I) { visitBinary(I, ISD::XOR); }
464 void visitShl (const User &I) { visitShift(I, ISD::SHL); }
465 void visitLShr(const User &I) { visitShift(I, ISD::SRL); }
466 void visitAShr(const User &I) { visitShift(I, ISD::SRA); }
467 void visitICmp(const User &I);
468 void visitFCmp(const User &I);
469 // Visit the conversion instructions
470 void visitTrunc(const User &I);
471 void visitZExt(const User &I);
472 void visitSExt(const User &I);
473 void visitFPTrunc(const User &I);
474 void visitFPExt(const User &I);
475 void visitFPToUI(const User &I);
476 void visitFPToSI(const User &I);
477 void visitUIToFP(const User &I);
478 void visitSIToFP(const User &I);
479 void visitPtrToInt(const User &I);
480 void visitIntToPtr(const User &I);
481 void visitBitCast(const User &I);
483 void visitExtractElement(const User &I);
484 void visitInsertElement(const User &I);
485 void visitShuffleVector(const User &I);
487 void visitExtractValue(const ExtractValueInst &I);
488 void visitInsertValue(const InsertValueInst &I);
490 void visitGetElementPtr(const User &I);
491 void visitSelect(const User &I);
493 void visitAlloca(const AllocaInst &I);
494 void visitLoad(const LoadInst &I);
495 void visitStore(const StoreInst &I);
496 void visitPHI(const PHINode &I);
497 void visitCall(const CallInst &I);
498 bool visitMemCmpCall(const CallInst &I);
500 void visitInlineAsm(ImmutableCallSite CS);
501 const char *visitIntrinsicCall(const CallInst &I, unsigned Intrinsic);
502 void visitTargetIntrinsic(const CallInst &I, unsigned Intrinsic);
504 void visitPow(const CallInst &I);
505 void visitExp2(const CallInst &I);
506 void visitExp(const CallInst &I);
507 void visitLog(const CallInst &I);
508 void visitLog2(const CallInst &I);
509 void visitLog10(const CallInst &I);
511 void visitVAStart(const CallInst &I);
512 void visitVAArg(const VAArgInst &I);
513 void visitVAEnd(const CallInst &I);
514 void visitVACopy(const CallInst &I);
516 void visitUserOp1(const Instruction &I) {
517 llvm_unreachable("UserOp1 should not exist at instruction selection time!");
519 void visitUserOp2(const Instruction &I) {
520 llvm_unreachable("UserOp2 should not exist at instruction selection time!");
523 const char *implVisitBinaryAtomic(const CallInst& I, ISD::NodeType Op);
524 const char *implVisitAluOverflow(const CallInst &I, ISD::NodeType Op);
526 void HandlePHINodesInSuccessorBlocks(const BasicBlock *LLVMBB);
528 /// EmitFuncArgumentDbgValue - If V is an function argument then create
529 /// corresponding DBG_VALUE machine instruction for it now. At the end of
530 /// instruction selection, they will be inserted to the entry BB.
531 bool EmitFuncArgumentDbgValue(const Value *V, MDNode *Variable,
532 int64_t Offset, const SDValue &N);
535 } // end namespace llvm