IndVarSimplify.cpp revision 4bd09d70cceb3851f7eb1c2f98338b3071d405f3
16148c02591bd83da7b957589c4bbf6f9720d503fChris Lattner//===- IndVarSimplify.cpp - Induction Variable Elimination ----------------===// 2fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman// 3b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// The LLVM Compiler Infrastructure 4b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// 5b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// This file was developed by the LLVM research group and is distributed under 6b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// the University of Illinois Open Source License. See LICENSE.TXT for details. 7fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman// 8b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell//===----------------------------------------------------------------------===// 96148c02591bd83da7b957589c4bbf6f9720d503fChris Lattner// 1040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// This transformation analyzes and transforms the induction variables (and 1140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// computations derived from them) into simpler forms suitable for subsequent 1240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// analysis and transformation. 1340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// 1440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// This transformation make the following changes to each loop with an 1540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// identifiable induction variable: 1640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// 1. All loops are transformed to have a SINGLE canonical induction variable 1740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// which starts at zero and steps by one. 1840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// 2. The canonical induction variable is guaranteed to be the first PHI node 1940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// in the loop header block. 2040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// 3. Any pointer arithmetic recurrences are raised to use array subscripts. 2140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// 2240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// If the trip count of a loop is computable, this pass also makes the following 2340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// changes: 2440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// 1. The exit condition for the loop is canonicalized to compare the 2540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// induction value against the exit value. This turns loops like: 2640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// 'for (i = 7; i*i < 1000; ++i)' into 'for (i = 0; i != 25; ++i)' 2740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// 2. Any use outside of the loop of an expression derived from the indvar 2840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// is changed to compute the derived value outside of the loop, eliminating 2940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// the dependence on the exit value of the induction variable. If the only 3040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// purpose of the loop is to compute the exit value of some derived 3140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// expression, this transformation will make the loop dead. 3240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// 3340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// This transformation should be followed by strength reduction after all of the 3440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// desired loop transformations have been performed. Additionally, on targets 3540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// where it is profitable, the loop could be transformed to count down to zero 3640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// (the "do loop" optimization). 376148c02591bd83da7b957589c4bbf6f9720d503fChris Lattner// 386148c02591bd83da7b957589c4bbf6f9720d503fChris Lattner//===----------------------------------------------------------------------===// 396148c02591bd83da7b957589c4bbf6f9720d503fChris Lattner 40022103b3f33febb7e54b8fdf2c9bc461eea78cbaChris Lattner#include "llvm/Transforms/Scalar.h" 4140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner#include "llvm/BasicBlock.h" 4259fdaeeae8f183e18bb6ad5c382ca23e28e6aaf6Chris Lattner#include "llvm/Constants.h" 4318b3c97bc773b24a66eb779e85da1820b0f16b31Chris Lattner#include "llvm/Instructions.h" 4440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner#include "llvm/Type.h" 4559fdaeeae8f183e18bb6ad5c382ca23e28e6aaf6Chris Lattner#include "llvm/Analysis/ScalarEvolutionExpressions.h" 4647df12d80db90e125e9f2ff764286ee11665476dJohn Criswell#include "llvm/Analysis/LoopInfo.h" 47455889aa79e3463a4b0f2161e3d9d72a683268b6Chris Lattner#include "llvm/Support/CFG.h" 48a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner#include "llvm/Support/GetElementPtrTypeIterator.h" 4947df12d80db90e125e9f2ff764286ee11665476dJohn Criswell#include "llvm/Transforms/Utils/Local.h" 50551ccae044b0ff658fe629dd67edd5ffe75d10e8Reid Spencer#include "llvm/Support/CommandLine.h" 51551ccae044b0ff658fe629dd67edd5ffe75d10e8Reid Spencer#include "llvm/ADT/Statistic.h" 5247df12d80db90e125e9f2ff764286ee11665476dJohn Criswellusing namespace llvm; 53d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke 545e76140536ba66fadeced1cd892f79616f407e3cChris Lattnernamespace { 554a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner /// SCEVExpander - This class uses information about analyze scalars to 564a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner /// rewrite expressions in canonical form. 574a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner /// 584a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner /// Clients should create an instance of this class when rewriting is needed, 594a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner /// and destroying it when finished to allow the release of the associated 604a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner /// memory. 614a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner struct SCEVExpander : public SCEVVisitor<SCEVExpander, Value*> { 624a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner ScalarEvolution &SE; 634a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner LoopInfo &LI; 644a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner std::map<SCEVHandle, Value*> InsertedExpressions; 654a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner std::set<Instruction*> InsertedInstructions; 664a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 674a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Instruction *InsertPt; 684a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 691fca5ff62bb2ecb5bfc8974f4dbfc56e9d3ca721Chris Lattner friend struct SCEVVisitor<SCEVExpander, Value*>; 704a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner public: 714a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner SCEVExpander(ScalarEvolution &se, LoopInfo &li) : SE(se), LI(li) {} 724a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 734a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner /// isInsertedInstruction - Return true if the specified instruction was 744a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner /// inserted by the code rewriter. If so, the client should not modify the 754a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner /// instruction. 764a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner bool isInsertedInstruction(Instruction *I) const { 774a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner return InsertedInstructions.count(I); 784a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner } 79fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 804a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner /// getOrInsertCanonicalInductionVariable - This method returns the 814a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner /// canonical induction variable of the specified type for the specified 824a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner /// loop (inserting one if there is none). A canonical induction variable 834a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner /// starts at zero and steps by one on each iteration. 844a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *getOrInsertCanonicalInductionVariable(const Loop *L, const Type *Ty){ 854a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner assert((Ty->isInteger() || Ty->isFloatingPoint()) && 864a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner "Can only insert integer or floating point induction variables!"); 874a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner SCEVHandle H = SCEVAddRecExpr::get(SCEVUnknown::getIntegerSCEV(0, Ty), 884a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner SCEVUnknown::getIntegerSCEV(1, Ty), L); 894a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner return expand(H); 904a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner } 914a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 924a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner /// addInsertedValue - Remember the specified instruction as being the 934a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner /// canonical form for the specified SCEV. 944a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner void addInsertedValue(Instruction *I, SCEV *S) { 954a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner InsertedExpressions[S] = (Value*)I; 964a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner InsertedInstructions.insert(I); 974a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner } 984a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 994a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner /// expandCodeFor - Insert code to directly compute the specified SCEV 1004a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner /// expression into the program. The inserted code is inserted into the 1014a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner /// specified block. 1024a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner /// 1034a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner /// If a particular value sign is required, a type may be specified for the 1044a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner /// result. 1054a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *expandCodeFor(SCEVHandle SH, Instruction *IP, const Type *Ty = 0) { 1064a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner // Expand the code for this SCEV. 1074a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner this->InsertPt = IP; 1084a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner return expandInTy(SH, Ty); 1094a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner } 1104a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 1114a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner protected: 1124a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *expand(SCEV *S) { 1134a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner // Check to see if we already expanded this. 1144a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner std::map<SCEVHandle, Value*>::iterator I = InsertedExpressions.find(S); 1154a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner if (I != InsertedExpressions.end()) 1164a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner return I->second; 1174a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 1184a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *V = visit(S); 1194a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner InsertedExpressions[S] = V; 1204a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner return V; 1214a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner } 1224a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 1234a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *expandInTy(SCEV *S, const Type *Ty) { 1244a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *V = expand(S); 1254a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner if (Ty && V->getType() != Ty) { 1264a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner // FIXME: keep track of the cast instruction. 1274a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner if (Constant *C = dyn_cast<Constant>(V)) 1284a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner return ConstantExpr::getCast(C, Ty); 1294a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner else if (Instruction *I = dyn_cast<Instruction>(V)) { 1304a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner // Check to see if there is already a cast. If there is, use it. 131fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); 1324a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner UI != E; ++UI) { 1334a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner if ((*UI)->getType() == Ty) 1344a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner if (CastInst *CI = dyn_cast<CastInst>(cast<Instruction>(*UI))) { 1354a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner BasicBlock::iterator It = I; ++It; 136f6249261a9467cb93c4ccf5ae24798e2977db5a0Chris Lattner if (isa<InvokeInst>(I)) 137f6249261a9467cb93c4ccf5ae24798e2977db5a0Chris Lattner It = cast<InvokeInst>(I)->getNormalDest()->begin(); 1384a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner while (isa<PHINode>(It)) ++It; 1394a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner if (It != BasicBlock::iterator(CI)) { 1404a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner // Splice the cast immediately after the operand in question. 141a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner BasicBlock::InstListType &InstList = 1428a7980b5eae56a741cced6993a98d94d2c617318Chris Lattner It->getParent()->getInstList(); 143989cbd58fb769e920fbf15b6a0fe0888aed553c9Chris Lattner InstList.splice(It, CI->getParent()->getInstList(), CI); 1444a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner } 1454a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner return CI; 1464a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner } 1474a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner } 1484a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner BasicBlock::iterator IP = I; ++IP; 1494a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner if (InvokeInst *II = dyn_cast<InvokeInst>(I)) 1504a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner IP = II->getNormalDest()->begin(); 1514a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner while (isa<PHINode>(IP)) ++IP; 1524a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner return new CastInst(V, Ty, V->getName(), IP); 1534a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner } else { 1544a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner // FIXME: check to see if there is already a cast! 1554a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner return new CastInst(V, Ty, V->getName(), InsertPt); 1564a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner } 1574a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner } 1584a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner return V; 1594a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner } 1604a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 1614a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *visitConstant(SCEVConstant *S) { 1624a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner return S->getValue(); 1634a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner } 1644a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 1654a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *visitTruncateExpr(SCEVTruncateExpr *S) { 1664a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *V = expand(S->getOperand()); 1674a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner return new CastInst(V, S->getType(), "tmp.", InsertPt); 1684a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner } 1694a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 1704a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *visitZeroExtendExpr(SCEVZeroExtendExpr *S) { 1712b994c7206b3872d908468fc926ba8db483cf0a3Chris Lattner Value *V = expandInTy(S->getOperand(),S->getType()->getUnsignedVersion()); 1724a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner return new CastInst(V, S->getType(), "tmp.", InsertPt); 1734a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner } 1744a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 1754a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *visitAddExpr(SCEVAddExpr *S) { 1764a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner const Type *Ty = S->getType(); 1774a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *V = expandInTy(S->getOperand(S->getNumOperands()-1), Ty); 1784a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 1794a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner // Emit a bunch of add instructions 1804a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner for (int i = S->getNumOperands()-2; i >= 0; --i) 181c5c5e6afe584ffbd2bf2ce755e65bc89f170053aChris Lattner V = BinaryOperator::createAdd(V, expandInTy(S->getOperand(i), Ty), 182c5c5e6afe584ffbd2bf2ce755e65bc89f170053aChris Lattner "tmp.", InsertPt); 1834a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner return V; 1844a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner } 1854a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 1864a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *visitMulExpr(SCEVMulExpr *S); 1874a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 1884a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *visitUDivExpr(SCEVUDivExpr *S) { 1894a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner const Type *Ty = S->getType(); 1904a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *LHS = expandInTy(S->getLHS(), Ty); 1914a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *RHS = expandInTy(S->getRHS(), Ty); 192c5c5e6afe584ffbd2bf2ce755e65bc89f170053aChris Lattner return BinaryOperator::createDiv(LHS, RHS, "tmp.", InsertPt); 1934a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner } 1944a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 1954a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *visitAddRecExpr(SCEVAddRecExpr *S); 1964a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 1974a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *visitUnknown(SCEVUnknown *S) { 1984a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner return S->getValue(); 1994a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner } 2004a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner }; 2014a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner} 2024a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 2034a7553e2da506a718f59869c03c5ce113eb40f7aChris LattnerValue *SCEVExpander::visitMulExpr(SCEVMulExpr *S) { 2044a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner const Type *Ty = S->getType(); 2054a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner int FirstOp = 0; // Set if we should emit a subtract. 2064a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner if (SCEVConstant *SC = dyn_cast<SCEVConstant>(S->getOperand(0))) 2074a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner if (SC->getValue()->isAllOnesValue()) 2084a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner FirstOp = 1; 209fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 2104a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner int i = S->getNumOperands()-2; 2114a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *V = expandInTy(S->getOperand(i+1), Ty); 212fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 2134a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner // Emit a bunch of multiply instructions 2144a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner for (; i >= FirstOp; --i) 215c5c5e6afe584ffbd2bf2ce755e65bc89f170053aChris Lattner V = BinaryOperator::createMul(V, expandInTy(S->getOperand(i), Ty), 216c5c5e6afe584ffbd2bf2ce755e65bc89f170053aChris Lattner "tmp.", InsertPt); 2174a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner // -1 * ... ---> 0 - ... 2184a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner if (FirstOp == 1) 219c5c5e6afe584ffbd2bf2ce755e65bc89f170053aChris Lattner V = BinaryOperator::createNeg(V, "tmp.", InsertPt); 2204a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner return V; 2214a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner} 2224a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 2234a7553e2da506a718f59869c03c5ce113eb40f7aChris LattnerValue *SCEVExpander::visitAddRecExpr(SCEVAddRecExpr *S) { 2244a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner const Type *Ty = S->getType(); 2254a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner const Loop *L = S->getLoop(); 2264a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner // We cannot yet do fp recurrences, e.g. the xform of {X,+,F} --> X+{0,+,F} 2274a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner assert(Ty->isIntegral() && "Cannot expand fp recurrences yet!"); 2284a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 2294a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner // {X,+,F} --> X + {0,+,F} 2304a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner if (!isa<SCEVConstant>(S->getStart()) || 2314a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner !cast<SCEVConstant>(S->getStart())->getValue()->isNullValue()) { 2324a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *Start = expandInTy(S->getStart(), Ty); 2334a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner std::vector<SCEVHandle> NewOps(S->op_begin(), S->op_end()); 2344a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner NewOps[0] = SCEVUnknown::getIntegerSCEV(0, Ty); 2354a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *Rest = expandInTy(SCEVAddRecExpr::get(NewOps, L), Ty); 2364a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 2374a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner // FIXME: look for an existing add to use. 238c5c5e6afe584ffbd2bf2ce755e65bc89f170053aChris Lattner return BinaryOperator::createAdd(Rest, Start, "tmp.", InsertPt); 2394a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner } 2404a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 2414a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner // {0,+,1} --> Insert a canonical induction variable into the loop! 2424a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner if (S->getNumOperands() == 2 && 2434a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner S->getOperand(1) == SCEVUnknown::getIntegerSCEV(1, Ty)) { 2444a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner // Create and insert the PHI node for the induction variable in the 2454a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner // specified loop. 2464a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner BasicBlock *Header = L->getHeader(); 2474a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner PHINode *PN = new PHINode(Ty, "indvar", Header->begin()); 2484a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner PN->addIncoming(Constant::getNullValue(Ty), L->getLoopPreheader()); 2494a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 2504a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner pred_iterator HPI = pred_begin(Header); 2514a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner assert(HPI != pred_end(Header) && "Loop with zero preds???"); 2524a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner if (!L->contains(*HPI)) ++HPI; 2534a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner assert(HPI != pred_end(Header) && L->contains(*HPI) && 2544a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner "No backedge in loop?"); 2554a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 2564a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner // Insert a unit add instruction right before the terminator corresponding 2574a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner // to the back-edge. 2584a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Constant *One = Ty->isFloatingPoint() ? (Constant*)ConstantFP::get(Ty, 1.0) 2594a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner : ConstantInt::get(Ty, 1); 260c5c5e6afe584ffbd2bf2ce755e65bc89f170053aChris Lattner Instruction *Add = BinaryOperator::createAdd(PN, One, "indvar.next", 261c5c5e6afe584ffbd2bf2ce755e65bc89f170053aChris Lattner (*HPI)->getTerminator()); 2624a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 2634a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner pred_iterator PI = pred_begin(Header); 2644a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner if (*PI == L->getLoopPreheader()) 2654a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner ++PI; 2664a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner PN->addIncoming(Add, *PI); 2674a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner return PN; 2684a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner } 2694a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 2704a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner // Get the canonical induction variable I for this loop. 2714a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *I = getOrInsertCanonicalInductionVariable(L, Ty); 2724a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 2734a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner if (S->getNumOperands() == 2) { // {0,+,F} --> i*F 2744a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *F = expandInTy(S->getOperand(1), Ty); 275c5c5e6afe584ffbd2bf2ce755e65bc89f170053aChris Lattner return BinaryOperator::createMul(I, F, "tmp.", InsertPt); 2764a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner } 2774a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 2784a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner // If this is a chain of recurrences, turn it into a closed form, using the 2794a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner // folders, then expandCodeFor the closed form. This allows the folders to 2804a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner // simplify the expression without having to build a bunch of special code 2814a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner // into this folder. 2824a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner SCEVHandle IH = SCEVUnknown::get(I); // Get I as a "symbolic" SCEV. 2834a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 2844a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner SCEVHandle V = S->evaluateAtIteration(IH); 2854a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner //std::cerr << "Evaluated: " << *this << "\n to: " << *V << "\n"; 2864a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 2874a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner return expandInTy(V, Ty); 2884a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner} 2894a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 2904a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner 2914a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattnernamespace { 292a92f696b74a99325026ebbdbffd2a44317e0c10bChris Lattner Statistic<> NumRemoved ("indvars", "Number of aux indvars removed"); 29340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Statistic<> NumPointer ("indvars", "Number of pointer indvars promoted"); 2943adf51d022348b06a1adeef7649fa35928ad9358Chris Lattner Statistic<> NumInserted("indvars", "Number of canonical indvars added"); 29540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Statistic<> NumReplaced("indvars", "Number of exit values replaced"); 29640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Statistic<> NumLFTR ("indvars", "Number of loop exit tests replaced"); 2973324e718bc9ac2ede08a14c325848b576849542bChris Lattner 2983324e718bc9ac2ede08a14c325848b576849542bChris Lattner class IndVarSimplify : public FunctionPass { 29940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner LoopInfo *LI; 30040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner ScalarEvolution *SE; 30115cad759fe2048ac5eb137c6bb0ab7287538677eChris Lattner bool Changed; 3023324e718bc9ac2ede08a14c325848b576849542bChris Lattner public: 3033324e718bc9ac2ede08a14c325848b576849542bChris Lattner virtual bool runOnFunction(Function &) { 30440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner LI = &getAnalysis<LoopInfo>(); 30540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner SE = &getAnalysis<ScalarEvolution>(); 30615cad759fe2048ac5eb137c6bb0ab7287538677eChris Lattner Changed = false; 30715cad759fe2048ac5eb137c6bb0ab7287538677eChris Lattner 3083324e718bc9ac2ede08a14c325848b576849542bChris Lattner // Induction Variables live in the header nodes of loops 30940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I) 310329c1c6c949d07e3fe9722ec633b4258217fd99dChris Lattner runOnLoop(*I); 3113324e718bc9ac2ede08a14c325848b576849542bChris Lattner return Changed; 3123324e718bc9ac2ede08a14c325848b576849542bChris Lattner } 3133324e718bc9ac2ede08a14c325848b576849542bChris Lattner 3143324e718bc9ac2ede08a14c325848b576849542bChris Lattner virtual void getAnalysisUsage(AnalysisUsage &AU) const { 3153324e718bc9ac2ede08a14c325848b576849542bChris Lattner AU.addRequiredID(LoopSimplifyID); 31640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner AU.addRequired<ScalarEvolution>(); 31740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner AU.addRequired<LoopInfo>(); 3183324e718bc9ac2ede08a14c325848b576849542bChris Lattner AU.addPreservedID(LoopSimplifyID); 3193324e718bc9ac2ede08a14c325848b576849542bChris Lattner AU.setPreservesCFG(); 3203324e718bc9ac2ede08a14c325848b576849542bChris Lattner } 32140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner private: 32240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner void runOnLoop(Loop *L); 32340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner void EliminatePointerRecurrence(PHINode *PN, BasicBlock *Preheader, 32440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner std::set<Instruction*> &DeadInsts); 32540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner void LinearFunctionTestReplace(Loop *L, SCEV *IterationCount, 3264a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner SCEVExpander &RW); 32740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner void RewriteLoopExitValues(Loop *L); 32840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 32940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner void DeleteTriviallyDeadInstructions(std::set<Instruction*> &Insts); 3303324e718bc9ac2ede08a14c325848b576849542bChris Lattner }; 3313324e718bc9ac2ede08a14c325848b576849542bChris Lattner RegisterOpt<IndVarSimplify> X("indvars", "Canonicalize Induction Variables"); 3325e76140536ba66fadeced1cd892f79616f407e3cChris Lattner} 333394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner 3344b5015604908e9296800991a7c538a255356428fChris LattnerFunctionPass *llvm::createIndVarSimplifyPass() { 3353324e718bc9ac2ede08a14c325848b576849542bChris Lattner return new IndVarSimplify(); 336394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner} 337394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner 33840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// DeleteTriviallyDeadInstructions - If any of the instructions is the 33940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// specified set are trivially dead, delete them and see if this makes any of 34040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// their operands subsequently dead. 34140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattnervoid IndVarSimplify:: 34240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris LattnerDeleteTriviallyDeadInstructions(std::set<Instruction*> &Insts) { 34340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner while (!Insts.empty()) { 34440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Instruction *I = *Insts.begin(); 34540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Insts.erase(Insts.begin()); 34640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (isInstructionTriviallyDead(I)) { 34740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) 34840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (Instruction *U = dyn_cast<Instruction>(I->getOperand(i))) 34940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Insts.insert(U); 35040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner SE->deleteInstructionFromRecords(I); 351a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner I->eraseFromParent(); 35240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Changed = true; 35340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 35440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 35540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner} 3563324e718bc9ac2ede08a14c325848b576849542bChris Lattner 3576148c02591bd83da7b957589c4bbf6f9720d503fChris Lattner 35840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// EliminatePointerRecurrence - Check to see if this is a trivial GEP pointer 35940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// recurrence. If so, change it into an integer recurrence, permitting 36040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// analysis by the SCEV routines. 361fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukmanvoid IndVarSimplify::EliminatePointerRecurrence(PHINode *PN, 36240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock *Preheader, 36340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner std::set<Instruction*> &DeadInsts) { 36440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner assert(PN->getNumIncomingValues() == 2 && "Noncanonicalized loop!"); 36540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner unsigned PreheaderIdx = PN->getBasicBlockIndex(Preheader); 36640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner unsigned BackedgeIdx = PreheaderIdx^1; 36740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (GetElementPtrInst *GEPI = 36840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner dyn_cast<GetElementPtrInst>(PN->getIncomingValue(BackedgeIdx))) 36940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (GEPI->getOperand(0) == PN) { 37040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner assert(GEPI->getNumOperands() == 2 && "GEP types must mismatch!"); 371fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 37240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Okay, we found a pointer recurrence. Transform this pointer 37340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // recurrence into an integer recurrence. Compute the value that gets 37440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // added to the pointer at every iteration. 37540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Value *AddedVal = GEPI->getOperand(1); 37640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 37740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Insert a new integer PHI node into the top of the block. 37840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner PHINode *NewPhi = new PHINode(AddedVal->getType(), 37940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner PN->getName()+".rec", PN); 380c5c5e6afe584ffbd2bf2ce755e65bc89f170053aChris Lattner NewPhi->addIncoming(Constant::getNullValue(NewPhi->getType()), Preheader); 381c5c5e6afe584ffbd2bf2ce755e65bc89f170053aChris Lattner 38240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Create the new add instruction. 383c5c5e6afe584ffbd2bf2ce755e65bc89f170053aChris Lattner Value *NewAdd = BinaryOperator::createAdd(NewPhi, AddedVal, 384c5c5e6afe584ffbd2bf2ce755e65bc89f170053aChris Lattner GEPI->getName()+".rec", GEPI); 38540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner NewPhi->addIncoming(NewAdd, PN->getIncomingBlock(BackedgeIdx)); 386fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 38740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Update the existing GEP to use the recurrence. 38840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner GEPI->setOperand(0, PN->getIncomingValue(PreheaderIdx)); 389fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 39040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Update the GEP to use the new recurrence we just inserted. 39140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner GEPI->setOperand(1, NewAdd); 39240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 393a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner // If the incoming value is a constant expr GEP, try peeling out the array 394a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner // 0 index if possible to make things simpler. 395a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner if (ConstantExpr *CE = dyn_cast<ConstantExpr>(GEPI->getOperand(0))) 396a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner if (CE->getOpcode() == Instruction::GetElementPtr) { 397a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner unsigned NumOps = CE->getNumOperands(); 398a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner assert(NumOps > 1 && "CE folding didn't work!"); 399a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner if (CE->getOperand(NumOps-1)->isNullValue()) { 400a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner // Check to make sure the last index really is an array index. 401a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner gep_type_iterator GTI = gep_type_begin(GEPI); 402a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner for (unsigned i = 1, e = GEPI->getNumOperands()-1; 403a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner i != e; ++i, ++GTI) 404a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner /*empty*/; 405a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner if (isa<SequentialType>(*GTI)) { 406a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner // Pull the last index out of the constant expr GEP. 407a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner std::vector<Value*> CEIdxs(CE->op_begin()+1, CE->op_end()-1); 408a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner Constant *NCE = ConstantExpr::getGetElementPtr(CE->getOperand(0), 409a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner CEIdxs); 410a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner GetElementPtrInst *NGEPI = 411a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner new GetElementPtrInst(NCE, Constant::getNullValue(Type::IntTy), 412a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner NewAdd, GEPI->getName(), GEPI); 413a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner GEPI->replaceAllUsesWith(NGEPI); 414a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner GEPI->eraseFromParent(); 415a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner GEPI = NGEPI; 416a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner } 417a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner } 418a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner } 419a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner 420a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner 42140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Finally, if there are any other users of the PHI node, we must 42240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // insert a new GEP instruction that uses the pre-incremented version 42340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // of the induction amount. 42440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (!PN->use_empty()) { 42540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock::iterator InsertPos = PN; ++InsertPos; 42640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner while (isa<PHINode>(InsertPos)) ++InsertPos; 42740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner std::string Name = PN->getName(); PN->setName(""); 42840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Value *PreInc = 42940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner new GetElementPtrInst(PN->getIncomingValue(PreheaderIdx), 43040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner std::vector<Value*>(1, NewPhi), Name, 43140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner InsertPos); 43240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner PN->replaceAllUsesWith(PreInc); 43340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 43440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 43540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Delete the old PHI for sure, and the GEP if its otherwise unused. 43640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner DeadInsts.insert(PN); 4373324e718bc9ac2ede08a14c325848b576849542bChris Lattner 43840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner ++NumPointer; 43940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Changed = true; 44040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 44140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner} 4423324e718bc9ac2ede08a14c325848b576849542bChris Lattner 44340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// LinearFunctionTestReplace - This method rewrites the exit condition of the 44459fdaeeae8f183e18bb6ad5c382ca23e28e6aaf6Chris Lattner/// loop to be a canonical != comparison against the incremented loop induction 44559fdaeeae8f183e18bb6ad5c382ca23e28e6aaf6Chris Lattner/// variable. This pass is able to rewrite the exit tests of any loop where the 44659fdaeeae8f183e18bb6ad5c382ca23e28e6aaf6Chris Lattner/// SCEV analysis can determine a loop-invariant trip count of the loop, which 44759fdaeeae8f183e18bb6ad5c382ca23e28e6aaf6Chris Lattner/// is actually a much broader range than just linear tests. 44840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattnervoid IndVarSimplify::LinearFunctionTestReplace(Loop *L, SCEV *IterationCount, 4494a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner SCEVExpander &RW) { 45040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Find the exit block for the loop. We can currently only handle loops with 45140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // a single exit. 452f1ab4b4eac5603d19c20f4a508f93a118a52bdd5Chris Lattner std::vector<BasicBlock*> ExitBlocks; 453f1ab4b4eac5603d19c20f4a508f93a118a52bdd5Chris Lattner L->getExitBlocks(ExitBlocks); 454f1ab4b4eac5603d19c20f4a508f93a118a52bdd5Chris Lattner if (ExitBlocks.size() != 1) return; 455f1ab4b4eac5603d19c20f4a508f93a118a52bdd5Chris Lattner BasicBlock *ExitBlock = ExitBlocks[0]; 45640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 45740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Make sure there is only one predecessor block in the loop. 45840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock *ExitingBlock = 0; 45940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner for (pred_iterator PI = pred_begin(ExitBlock), PE = pred_end(ExitBlock); 46040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner PI != PE; ++PI) 46140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (L->contains(*PI)) { 46240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (ExitingBlock == 0) 46340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner ExitingBlock = *PI; 46440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner else 46540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner return; // Multiple exits from loop to this block. 46640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 46740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner assert(ExitingBlock && "Loop info is broken"); 46840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 46940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (!isa<BranchInst>(ExitingBlock->getTerminator())) 47040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner return; // Can't rewrite non-branch yet 47140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BranchInst *BI = cast<BranchInst>(ExitingBlock->getTerminator()); 47240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner assert(BI->isConditional() && "Must be conditional to be part of loop!"); 47340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 47440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner std::set<Instruction*> InstructionsToDelete; 47540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (Instruction *Cond = dyn_cast<Instruction>(BI->getCondition())) 47640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner InstructionsToDelete.insert(Cond); 47740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 478d244057a48660c3cd30d219118ece3f947947790Chris Lattner // If the exiting block is not the same as the backedge block, we must compare 479d244057a48660c3cd30d219118ece3f947947790Chris Lattner // against the preincremented value, otherwise we prefer to compare against 480d244057a48660c3cd30d219118ece3f947947790Chris Lattner // the post-incremented value. 481d244057a48660c3cd30d219118ece3f947947790Chris Lattner BasicBlock *Header = L->getHeader(); 482d244057a48660c3cd30d219118ece3f947947790Chris Lattner pred_iterator HPI = pred_begin(Header); 483d244057a48660c3cd30d219118ece3f947947790Chris Lattner assert(HPI != pred_end(Header) && "Loop with zero preds???"); 484d244057a48660c3cd30d219118ece3f947947790Chris Lattner if (!L->contains(*HPI)) ++HPI; 485d244057a48660c3cd30d219118ece3f947947790Chris Lattner assert(HPI != pred_end(Header) && L->contains(*HPI) && 486d244057a48660c3cd30d219118ece3f947947790Chris Lattner "No backedge in loop?"); 487d244057a48660c3cd30d219118ece3f947947790Chris Lattner 488d244057a48660c3cd30d219118ece3f947947790Chris Lattner SCEVHandle TripCount = IterationCount; 489d244057a48660c3cd30d219118ece3f947947790Chris Lattner Value *IndVar; 490d244057a48660c3cd30d219118ece3f947947790Chris Lattner if (*HPI == ExitingBlock) { 491d244057a48660c3cd30d219118ece3f947947790Chris Lattner // The IterationCount expression contains the number of times that the 492d244057a48660c3cd30d219118ece3f947947790Chris Lattner // backedge actually branches to the loop header. This is one less than the 493d244057a48660c3cd30d219118ece3f947947790Chris Lattner // number of times the loop executes, so add one to it. 494d244057a48660c3cd30d219118ece3f947947790Chris Lattner Constant *OneC = ConstantInt::get(IterationCount->getType(), 1); 495d244057a48660c3cd30d219118ece3f947947790Chris Lattner TripCount = SCEVAddExpr::get(IterationCount, SCEVUnknown::get(OneC)); 496d244057a48660c3cd30d219118ece3f947947790Chris Lattner IndVar = L->getCanonicalInductionVariableIncrement(); 497d244057a48660c3cd30d219118ece3f947947790Chris Lattner } else { 498d244057a48660c3cd30d219118ece3f947947790Chris Lattner // We have to use the preincremented value... 499d244057a48660c3cd30d219118ece3f947947790Chris Lattner IndVar = L->getCanonicalInductionVariable(); 500d244057a48660c3cd30d219118ece3f947947790Chris Lattner } 50159fdaeeae8f183e18bb6ad5c382ca23e28e6aaf6Chris Lattner 50240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Expand the code for the iteration count into the preheader of the loop. 50340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock *Preheader = L->getLoopPreheader(); 5044a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *ExitCnt = RW.expandCodeFor(TripCount, Preheader->getTerminator(), 50540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner IndVar->getType()); 50640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 50740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Insert a new setne or seteq instruction before the branch. 50840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Instruction::BinaryOps Opcode; 50940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (L->contains(BI->getSuccessor(0))) 51040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Opcode = Instruction::SetNE; 51140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner else 51240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Opcode = Instruction::SetEQ; 51340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 51440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Value *Cond = new SetCondInst(Opcode, IndVar, ExitCnt, "exitcond", BI); 51540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BI->setCondition(Cond); 51640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner ++NumLFTR; 51740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Changed = true; 51840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 51940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner DeleteTriviallyDeadInstructions(InstructionsToDelete); 52040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner} 5213324e718bc9ac2ede08a14c325848b576849542bChris Lattner 5223324e718bc9ac2ede08a14c325848b576849542bChris Lattner 52340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// RewriteLoopExitValues - Check to see if this loop has a computable 52440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// loop-invariant execution count. If so, this means that we can compute the 52540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// final value of any expressions that are recurrent in the loop, and 52640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// substitute the exit values from the loop into any instructions outside of 52740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// the loop that use the final values of the current expressions. 52840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattnervoid IndVarSimplify::RewriteLoopExitValues(Loop *L) { 52940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock *Preheader = L->getLoopPreheader(); 53040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 53140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Scan all of the instructions in the loop, looking at those that have 53240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // extra-loop users and which are recurrences. 5334a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner SCEVExpander Rewriter(*SE, *LI); 53440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 53540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // We insert the code into the preheader of the loop if the loop contains 53640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // multiple exit blocks, or in the exit block if there is exactly one. 53740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock *BlockToInsertInto; 538f1ab4b4eac5603d19c20f4a508f93a118a52bdd5Chris Lattner std::vector<BasicBlock*> ExitBlocks; 539f1ab4b4eac5603d19c20f4a508f93a118a52bdd5Chris Lattner L->getExitBlocks(ExitBlocks); 540f1ab4b4eac5603d19c20f4a508f93a118a52bdd5Chris Lattner if (ExitBlocks.size() == 1) 541f1ab4b4eac5603d19c20f4a508f93a118a52bdd5Chris Lattner BlockToInsertInto = ExitBlocks[0]; 54240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner else 54340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BlockToInsertInto = Preheader; 54440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock::iterator InsertPt = BlockToInsertInto->begin(); 54540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner while (isa<PHINode>(InsertPt)) ++InsertPt; 54640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 54720aa098ba694aa7e3f5fb5a52d22dba7c1e857aeChris Lattner bool HasConstantItCount = isa<SCEVConstant>(SE->getIterationCount(L)); 54820aa098ba694aa7e3f5fb5a52d22dba7c1e857aeChris Lattner 54940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner std::set<Instruction*> InstructionsToDelete; 550fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 55140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner for (unsigned i = 0, e = L->getBlocks().size(); i != e; ++i) 55240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (LI->getLoopFor(L->getBlocks()[i]) == L) { // Not in a subloop... 55340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock *BB = L->getBlocks()[i]; 5544bd09d70cceb3851f7eb1c2f98338b3071d405f3Chris Lattner for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;) { 55540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (I->getType()->isInteger()) { // Is an integer instruction 55640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner SCEVHandle SH = SE->getSCEV(I); 55720aa098ba694aa7e3f5fb5a52d22dba7c1e857aeChris Lattner if (SH->hasComputableLoopEvolution(L) || // Varies predictably 55820aa098ba694aa7e3f5fb5a52d22dba7c1e857aeChris Lattner HasConstantItCount) { 55940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Find out if this predictably varying value is actually used 56040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // outside of the loop. "extra" as opposed to "intra". 56140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner std::vector<User*> ExtraLoopUsers; 56240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); 56340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner UI != E; ++UI) 56440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (!L->contains(cast<Instruction>(*UI)->getParent())) 56540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner ExtraLoopUsers.push_back(*UI); 56640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (!ExtraLoopUsers.empty()) { 56740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Okay, this instruction has a user outside of the current loop 56840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // and varies predictably in this loop. Evaluate the value it 56940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // contains when the loop exits, and insert code for it. 57020aa098ba694aa7e3f5fb5a52d22dba7c1e857aeChris Lattner SCEVHandle ExitValue = SE->getSCEVAtScope(I, L->getParentLoop()); 57140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (!isa<SCEVCouldNotCompute>(ExitValue)) { 57240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Changed = true; 57340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner ++NumReplaced; 5744bd09d70cceb3851f7eb1c2f98338b3071d405f3Chris Lattner // Remember the next instruction. The rewriter can move code 5754bd09d70cceb3851f7eb1c2f98338b3071d405f3Chris Lattner // around in some cases. 5764bd09d70cceb3851f7eb1c2f98338b3071d405f3Chris Lattner BasicBlock::iterator NextI = I; ++NextI; 5774bd09d70cceb3851f7eb1c2f98338b3071d405f3Chris Lattner 5784a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *NewVal = Rewriter.expandCodeFor(ExitValue, InsertPt, 57940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner I->getType()); 58040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 58140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Rewrite any users of the computed value outside of the loop 58240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // with the newly computed value. 58340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner for (unsigned i = 0, e = ExtraLoopUsers.size(); i != e; ++i) 58440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner ExtraLoopUsers[i]->replaceUsesOfWith(I, NewVal); 58540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 58640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // If this instruction is dead now, schedule it to be removed. 58740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (I->use_empty()) 58840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner InstructionsToDelete.insert(I); 5894bd09d70cceb3851f7eb1c2f98338b3071d405f3Chris Lattner I = NextI; 5904bd09d70cceb3851f7eb1c2f98338b3071d405f3Chris Lattner continue; // Skip the ++I 59140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 59240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 59340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 59440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 5954bd09d70cceb3851f7eb1c2f98338b3071d405f3Chris Lattner 5964bd09d70cceb3851f7eb1c2f98338b3071d405f3Chris Lattner // Next instruction. Continue instruction skips this. 5974bd09d70cceb3851f7eb1c2f98338b3071d405f3Chris Lattner ++I; 5984bd09d70cceb3851f7eb1c2f98338b3071d405f3Chris Lattner } 5993324e718bc9ac2ede08a14c325848b576849542bChris Lattner } 6006148c02591bd83da7b957589c4bbf6f9720d503fChris Lattner 60140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner DeleteTriviallyDeadInstructions(InstructionsToDelete); 60240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner} 60315cad759fe2048ac5eb137c6bb0ab7287538677eChris Lattner 60415cad759fe2048ac5eb137c6bb0ab7287538677eChris Lattner 60540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattnervoid IndVarSimplify::runOnLoop(Loop *L) { 60640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // First step. Check to see if there are any trivial GEP pointer recurrences. 60740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // If there are, change them into integer recurrences, permitting analysis by 60840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // the SCEV routines. 60915cad759fe2048ac5eb137c6bb0ab7287538677eChris Lattner // 61040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock *Header = L->getHeader(); 61140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock *Preheader = L->getLoopPreheader(); 612fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 61340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner std::set<Instruction*> DeadInsts; 6142da5c3dda6f5b9c4ec6d55008d33327764364bd4Reid Spencer for (BasicBlock::iterator I = Header->begin(); isa<PHINode>(I); ++I) { 6152da5c3dda6f5b9c4ec6d55008d33327764364bd4Reid Spencer PHINode *PN = cast<PHINode>(I); 61640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (isa<PointerType>(PN->getType())) 61740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner EliminatePointerRecurrence(PN, Preheader, DeadInsts); 6182da5c3dda6f5b9c4ec6d55008d33327764364bd4Reid Spencer } 61915cad759fe2048ac5eb137c6bb0ab7287538677eChris Lattner 62040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (!DeadInsts.empty()) 62140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner DeleteTriviallyDeadInstructions(DeadInsts); 622394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner 623394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner 62440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Next, transform all loops nesting inside of this loop. 62540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner for (LoopInfo::iterator I = L->begin(), E = L->end(); I != E; ++I) 62640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner runOnLoop(*I); 627394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner 62840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Check to see if this loop has a computable loop-invariant execution count. 62940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // If so, this means that we can compute the final value of any expressions 63040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // that are recurrent in the loop, and substitute the exit values from the 63140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // loop into any instructions outside of the loop that use the final values of 63240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // the current expressions. 633394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner // 63440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner SCEVHandle IterationCount = SE->getIterationCount(L); 63540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (!isa<SCEVCouldNotCompute>(IterationCount)) 63640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner RewriteLoopExitValues(L); 63740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 63840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Next, analyze all of the induction variables in the loop, canonicalizing 63940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // auxillary induction variables. 64040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner std::vector<std::pair<PHINode*, SCEVHandle> > IndVars; 64140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 6422da5c3dda6f5b9c4ec6d55008d33327764364bd4Reid Spencer for (BasicBlock::iterator I = Header->begin(); isa<PHINode>(I); ++I) { 6432da5c3dda6f5b9c4ec6d55008d33327764364bd4Reid Spencer PHINode *PN = cast<PHINode>(I); 64440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (PN->getType()->isInteger()) { // FIXME: when we have fast-math, enable! 64540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner SCEVHandle SCEV = SE->getSCEV(PN); 64640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (SCEV->hasComputableLoopEvolution(L)) 647a25502acd7c0d56cbd20da37f25830d81be834c5Chris Lattner // FIXME: Without a strength reduction pass, it is an extremely bad idea 648a25502acd7c0d56cbd20da37f25830d81be834c5Chris Lattner // to indvar substitute anything more complex than a linear induction 649a25502acd7c0d56cbd20da37f25830d81be834c5Chris Lattner // variable. Doing so will put expensive multiply instructions inside 650a25502acd7c0d56cbd20da37f25830d81be834c5Chris Lattner // of the loop. For now just disable indvar subst on anything more 651a25502acd7c0d56cbd20da37f25830d81be834c5Chris Lattner // complex than a linear addrec. 652595ee7ec26432e4804f1e71817d9cf9b1f86318dChris Lattner if (SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(SCEV)) 653595ee7ec26432e4804f1e71817d9cf9b1f86318dChris Lattner if (AR->getNumOperands() == 2 && isa<SCEVConstant>(AR->getOperand(1))) 654595ee7ec26432e4804f1e71817d9cf9b1f86318dChris Lattner IndVars.push_back(std::make_pair(PN, SCEV)); 65540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 6562da5c3dda6f5b9c4ec6d55008d33327764364bd4Reid Spencer } 657f016ea4ff80c56c467247a90567dd07bddb590f3Chris Lattner 65840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // If there are no induction variables in the loop, there is nothing more to 65940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // do. 660f50af088f19f525f3d1026eb61db77e0037a9f43Chris Lattner if (IndVars.empty()) { 661f50af088f19f525f3d1026eb61db77e0037a9f43Chris Lattner // Actually, if we know how many times the loop iterates, lets insert a 662f50af088f19f525f3d1026eb61db77e0037a9f43Chris Lattner // canonical induction variable to help subsequent passes. 663f50af088f19f525f3d1026eb61db77e0037a9f43Chris Lattner if (!isa<SCEVCouldNotCompute>(IterationCount)) { 6644a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner SCEVExpander Rewriter(*SE, *LI); 6654a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Rewriter.getOrInsertCanonicalInductionVariable(L, 666f50af088f19f525f3d1026eb61db77e0037a9f43Chris Lattner IterationCount->getType()); 667f50af088f19f525f3d1026eb61db77e0037a9f43Chris Lattner LinearFunctionTestReplace(L, IterationCount, Rewriter); 668f50af088f19f525f3d1026eb61db77e0037a9f43Chris Lattner } 669f50af088f19f525f3d1026eb61db77e0037a9f43Chris Lattner return; 670f50af088f19f525f3d1026eb61db77e0037a9f43Chris Lattner } 671f016ea4ff80c56c467247a90567dd07bddb590f3Chris Lattner 67240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Compute the type of the largest recurrence expression. 67340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // 67440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner const Type *LargestType = IndVars[0].first->getType(); 675fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner bool DifferingSizes = false; 67640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner for (unsigned i = 1, e = IndVars.size(); i != e; ++i) { 67740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner const Type *Ty = IndVars[i].first->getType(); 678fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner DifferingSizes |= Ty->getPrimitiveSize() != LargestType->getPrimitiveSize(); 67940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (Ty->getPrimitiveSize() > LargestType->getPrimitiveSize()) 68040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner LargestType = Ty; 681500597a1c39e91a3020587318ed61e737b6c613aChris Lattner } 682394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner 68340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Create a rewriter object which we'll use to transform the code with. 6844a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner SCEVExpander Rewriter(*SE, *LI); 68540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 68640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Now that we know the largest of of the induction variables in this loop, 68740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // insert a canonical induction variable of the largest size. 688006118fe8c73d8009d7952b84cabd50882ed0033Chris Lattner LargestType = LargestType->getUnsignedVersion(); 6894a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *IndVar = Rewriter.getOrInsertCanonicalInductionVariable(L,LargestType); 69040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner ++NumInserted; 69140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Changed = true; 69240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 69340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (!isa<SCEVCouldNotCompute>(IterationCount)) 69459fdaeeae8f183e18bb6ad5c382ca23e28e6aaf6Chris Lattner LinearFunctionTestReplace(L, IterationCount, Rewriter); 69540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 69640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Now that we have a canonical induction variable, we can rewrite any 69740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // recurrences in terms of the induction variable. Start with the auxillary 69840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // induction variables, and recursively rewrite any of their uses. 69940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock::iterator InsertPt = Header->begin(); 70040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner while (isa<PHINode>(InsertPt)) ++InsertPt; 70140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 7025d461d20aea308471f2a31b718a274bfee28b60cChris Lattner // If there were induction variables of other sizes, cast the primary 7035d461d20aea308471f2a31b718a274bfee28b60cChris Lattner // induction variable to the right size for them, avoiding the need for the 7045d461d20aea308471f2a31b718a274bfee28b60cChris Lattner // code evaluation methods to insert induction variables of different sizes. 705fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner if (DifferingSizes) { 706fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner bool InsertedSizes[17] = { false }; 707fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner InsertedSizes[LargestType->getPrimitiveSize()] = true; 708fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner for (unsigned i = 0, e = IndVars.size(); i != e; ++i) 709fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner if (!InsertedSizes[IndVars[i].first->getType()->getPrimitiveSize()]) { 710fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner PHINode *PN = IndVars[i].first; 711fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner InsertedSizes[PN->getType()->getPrimitiveSize()] = true; 712fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner Instruction *New = new CastInst(IndVar, 713fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner PN->getType()->getUnsignedVersion(), 714fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner "indvar", InsertPt); 715fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner Rewriter.addInsertedValue(New, SE->getSCEV(New)); 716fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner } 717fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner } 718fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner 719fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner // If there were induction variables of other sizes, cast the primary 720fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner // induction variable to the right size for them, avoiding the need for the 721fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner // code evaluation methods to insert induction variables of different sizes. 7225d461d20aea308471f2a31b718a274bfee28b60cChris Lattner std::map<unsigned, Value*> InsertedSizes; 72340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner while (!IndVars.empty()) { 72440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner PHINode *PN = IndVars.back().first; 7254a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *NewVal = Rewriter.expandCodeFor(IndVars.back().second, InsertPt, 726fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner PN->getType()); 727fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner std::string Name = PN->getName(); 728fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner PN->setName(""); 729fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner NewVal->setName(Name); 7305d461d20aea308471f2a31b718a274bfee28b60cChris Lattner 73140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Replace the old PHI Node with the inserted computation. 732fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner PN->replaceAllUsesWith(NewVal); 73340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner DeadInsts.insert(PN); 73440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner IndVars.pop_back(); 73540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner ++NumRemoved; 73640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Changed = true; 737500597a1c39e91a3020587318ed61e737b6c613aChris Lattner } 738ba4f3f6a419326df190599421fa149c90235cb72Chris Lattner 739b4782d13d1444d9d18c0a681292cf0d0a32cf3efChris Lattner#if 0 7401363e85df74627530ceede53280613c62a4cdbe3Chris Lattner // Now replace all derived expressions in the loop body with simpler 7411363e85df74627530ceede53280613c62a4cdbe3Chris Lattner // expressions. 74240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner for (unsigned i = 0, e = L->getBlocks().size(); i != e; ++i) 74340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (LI->getLoopFor(L->getBlocks()[i]) == L) { // Not in a subloop... 74440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock *BB = L->getBlocks()[i]; 74540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) 74640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (I->getType()->isInteger() && // Is an integer instruction 7471363e85df74627530ceede53280613c62a4cdbe3Chris Lattner !I->use_empty() && 74840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner !Rewriter.isInsertedInstruction(I)) { 74940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner SCEVHandle SH = SE->getSCEV(I); 7504a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *V = Rewriter.expandCodeFor(SH, I, I->getType()); 7511363e85df74627530ceede53280613c62a4cdbe3Chris Lattner if (V != I) { 7521363e85df74627530ceede53280613c62a4cdbe3Chris Lattner if (isa<Instruction>(V)) { 7531363e85df74627530ceede53280613c62a4cdbe3Chris Lattner std::string Name = I->getName(); 7541363e85df74627530ceede53280613c62a4cdbe3Chris Lattner I->setName(""); 7551363e85df74627530ceede53280613c62a4cdbe3Chris Lattner V->setName(Name); 7561363e85df74627530ceede53280613c62a4cdbe3Chris Lattner } 7571363e85df74627530ceede53280613c62a4cdbe3Chris Lattner I->replaceAllUsesWith(V); 7581363e85df74627530ceede53280613c62a4cdbe3Chris Lattner DeadInsts.insert(I); 7591363e85df74627530ceede53280613c62a4cdbe3Chris Lattner ++NumRemoved; 7601363e85df74627530ceede53280613c62a4cdbe3Chris Lattner Changed = true; 761fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman } 76240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 763394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner } 764b4782d13d1444d9d18c0a681292cf0d0a32cf3efChris Lattner#endif 7651363e85df74627530ceede53280613c62a4cdbe3Chris Lattner 7661363e85df74627530ceede53280613c62a4cdbe3Chris Lattner DeleteTriviallyDeadInstructions(DeadInsts); 7676148c02591bd83da7b957589c4bbf6f9720d503fChris Lattner} 768