Ted Kremenek | 11de5cb | 2007-09-20 21:42:55 +0000 | [diff] [blame] | 1 | //=- LiveVariables.cpp - Live Variable Analysis for Source CFGs -*- C++ --*-==// |
Ted Kremenek | e4e6334 | 2007-09-06 00:17:54 +0000 | [diff] [blame] | 2 | // |
| 3 | // The LLVM Compiler Infrastructure |
| 4 | // |
| 5 | // This file was developed by Ted Kremenek and is distributed under |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 6 | // the University of Illinois Open Source License. See LICENSE.TXT for |
| 7 | // details. |
Ted Kremenek | e4e6334 | 2007-09-06 00:17:54 +0000 | [diff] [blame] | 8 | // |
| 9 | //===----------------------------------------------------------------------===// |
| 10 | // |
| 11 | // This file implements Live Variables analysis for source-level CFGs. |
| 12 | // |
| 13 | //===----------------------------------------------------------------------===// |
| 14 | |
| 15 | #include "clang/Analysis/LiveVariables.h" |
Ted Kremenek | 27b07c5 | 2007-09-06 21:26:58 +0000 | [diff] [blame] | 16 | #include "clang/Basic/SourceManager.h" |
Ted Kremenek | e4e6334 | 2007-09-06 00:17:54 +0000 | [diff] [blame] | 17 | #include "clang/AST/Expr.h" |
| 18 | #include "clang/AST/CFG.h" |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 19 | #include "clang/Analysis/Visitors/CFGRecStmtDeclVisitor.h" |
| 20 | #include "DataflowSolver.h" |
Ted Kremenek | e4e6334 | 2007-09-06 00:17:54 +0000 | [diff] [blame] | 21 | #include "clang/Lex/IdentifierTable.h" |
| 22 | #include "llvm/ADT/SmallPtrSet.h" |
| 23 | |
Ted Kremenek | 27b07c5 | 2007-09-06 21:26:58 +0000 | [diff] [blame] | 24 | #include <string.h> |
| 25 | #include <stdio.h> |
Ted Kremenek | e4e6334 | 2007-09-06 00:17:54 +0000 | [diff] [blame] | 26 | |
| 27 | using namespace clang; |
| 28 | |
| 29 | //===----------------------------------------------------------------------===// |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 30 | // Dataflow initialization logic. |
| 31 | //===----------------------------------------------------------------------===// |
Ted Kremenek | e4e6334 | 2007-09-06 00:17:54 +0000 | [diff] [blame] | 32 | |
| 33 | namespace { |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 34 | struct RegisterDecls : public CFGRecStmtDeclVisitor<RegisterDecls> { |
| 35 | LiveVariables::AnalysisDataTy& AD; |
| 36 | void VisitVarDecl(VarDecl* VD) { AD.RegisterDecl(VD); } |
Ted Kremenek | e4e6334 | 2007-09-06 00:17:54 +0000 | [diff] [blame] | 37 | |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 38 | RegisterDecls(LiveVariables::AnalysisDataTy& ad) : AD(ad) {} |
| 39 | }; |
Ted Kremenek | e4e6334 | 2007-09-06 00:17:54 +0000 | [diff] [blame] | 40 | } // end anonymous namespace |
| 41 | |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 42 | void LiveVariables::InitializeValues(const CFG& cfg) { |
| 43 | RegisterDecls R(getAnalysisData()); |
| 44 | cfg.VisitBlockStmts(R); |
| 45 | } |
Ted Kremenek | e4e6334 | 2007-09-06 00:17:54 +0000 | [diff] [blame] | 46 | |
| 47 | //===----------------------------------------------------------------------===// |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 48 | // Transfer functions. |
| 49 | //===----------------------------------------------------------------------===// |
Ted Kremenek | e4e6334 | 2007-09-06 00:17:54 +0000 | [diff] [blame] | 50 | |
| 51 | namespace { |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 52 | class TransferFuncs : public CFGStmtVisitor<TransferFuncs> { |
| 53 | LiveVariables::AnalysisDataTy& AD; |
| 54 | LiveVariables::ValTy Live; |
Ted Kremenek | e4e6334 | 2007-09-06 00:17:54 +0000 | [diff] [blame] | 55 | public: |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 56 | TransferFuncs(LiveVariables::AnalysisDataTy& ad) : AD(ad) {} |
| 57 | |
| 58 | LiveVariables::ValTy& getVal() { return Live; } |
Ted Kremenek | f175805 | 2007-09-12 19:10:52 +0000 | [diff] [blame] | 59 | |
Ted Kremenek | e4e6334 | 2007-09-06 00:17:54 +0000 | [diff] [blame] | 60 | void VisitDeclRefExpr(DeclRefExpr* DR); |
| 61 | void VisitBinaryOperator(BinaryOperator* B); |
| 62 | void VisitAssign(BinaryOperator* B); |
Ted Kremenek | 27b07c5 | 2007-09-06 21:26:58 +0000 | [diff] [blame] | 63 | void VisitDeclStmt(DeclStmt* DS); |
| 64 | void VisitUnaryOperator(UnaryOperator* U); |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 65 | void VisitStmt(Stmt* S) { VisitChildren(S); } |
| 66 | void Visit(Stmt *S) { |
| 67 | if (AD.Observer) AD.Observer->ObserveStmt(S,AD,Live); |
| 68 | static_cast<CFGStmtVisitor<TransferFuncs>*>(this)->Visit(S); |
Ted Kremenek | e4e6334 | 2007-09-06 00:17:54 +0000 | [diff] [blame] | 69 | } |
Ted Kremenek | e4e6334 | 2007-09-06 00:17:54 +0000 | [diff] [blame] | 70 | }; |
| 71 | |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 72 | void TransferFuncs::VisitDeclRefExpr(DeclRefExpr* DR) { |
| 73 | if (VarDecl* V = dyn_cast<VarDecl>(DR->getDecl())) |
| 74 | Live.set(AD[V]); // Register a use of the variable. |
Ted Kremenek | e4e6334 | 2007-09-06 00:17:54 +0000 | [diff] [blame] | 75 | } |
Ted Kremenek | e4e6334 | 2007-09-06 00:17:54 +0000 | [diff] [blame] | 76 | |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 77 | void TransferFuncs::VisitBinaryOperator(BinaryOperator* B) { |
Ted Kremenek | f175805 | 2007-09-12 19:10:52 +0000 | [diff] [blame] | 78 | if (B->isAssignmentOp()) VisitAssign(B); |
| 79 | else VisitStmt(B); |
Ted Kremenek | e4e6334 | 2007-09-06 00:17:54 +0000 | [diff] [blame] | 80 | } |
| 81 | |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 82 | void TransferFuncs::VisitUnaryOperator(UnaryOperator* U) { |
Ted Kremenek | 27b07c5 | 2007-09-06 21:26:58 +0000 | [diff] [blame] | 83 | switch (U->getOpcode()) { |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 84 | case UnaryOperator::PostInc: |
| 85 | case UnaryOperator::PostDec: |
| 86 | case UnaryOperator::PreInc: |
| 87 | case UnaryOperator::PreDec: |
| 88 | case UnaryOperator::AddrOf: |
| 89 | // Walk through the subexpressions, blasting through ParenExprs |
| 90 | // until we either find a DeclRefExpr or some non-DeclRefExpr |
| 91 | // expression. |
| 92 | for (Stmt* S = U->getSubExpr() ;;) { |
| 93 | if (ParenExpr* P = dyn_cast<ParenExpr>(S)) { S=P->getSubExpr(); continue;} |
| 94 | else if (DeclRefExpr* DR = dyn_cast<DeclRefExpr>(S)) { |
| 95 | // Treat the --/++/& operator as a kill. |
| 96 | Live.reset(AD[DR->getDecl()]); |
| 97 | if (AD.Observer) AD.Observer->ObserverKill(DR); |
| 98 | VisitDeclRefExpr(DR); |
| 99 | } |
| 100 | else Visit(S); |
Ted Kremenek | 27b07c5 | 2007-09-06 21:26:58 +0000 | [diff] [blame] | 101 | |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 102 | break; |
| 103 | } |
| 104 | break; |
| 105 | |
| 106 | default: |
| 107 | Visit(U->getSubExpr()); |
| 108 | break; |
Ted Kremenek | 27b07c5 | 2007-09-06 21:26:58 +0000 | [diff] [blame] | 109 | } |
| 110 | } |
| 111 | |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 112 | void TransferFuncs::VisitAssign(BinaryOperator* B) { |
Ted Kremenek | e4e6334 | 2007-09-06 00:17:54 +0000 | [diff] [blame] | 113 | Stmt* LHS = B->getLHS(); |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 114 | |
| 115 | if (DeclRefExpr* DR = dyn_cast<DeclRefExpr>(LHS)) { // Assigning to a var? |
| 116 | Live.reset(AD[DR->getDecl()]); |
| 117 | if (AD.Observer) AD.Observer->ObserverKill(DR); |
| 118 | // Handle things like +=, etc., which also generate "uses" |
| 119 | // of a variable. Do this just by visiting the subexpression. |
| 120 | if (B->getOpcode() != BinaryOperator::Assign) Visit(LHS); |
Ted Kremenek | e4e6334 | 2007-09-06 00:17:54 +0000 | [diff] [blame] | 121 | } |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 122 | else // Not assigning to a variable. Process LHS as usual. |
Ted Kremenek | 27b07c5 | 2007-09-06 21:26:58 +0000 | [diff] [blame] | 123 | Visit(LHS); |
Ted Kremenek | e4e6334 | 2007-09-06 00:17:54 +0000 | [diff] [blame] | 124 | |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 125 | Visit(B->getRHS()); |
Ted Kremenek | e4e6334 | 2007-09-06 00:17:54 +0000 | [diff] [blame] | 126 | } |
| 127 | |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 128 | void TransferFuncs::VisitDeclStmt(DeclStmt* DS) { |
| 129 | // Declarations effectively "kill" a variable since they cannot |
| 130 | // possibly be live before they are declared. |
Steve Naroff | 9474504 | 2007-09-13 23:52:58 +0000 | [diff] [blame] | 131 | for (ScopedDecl* D = DS->getDecl(); D != NULL ; D = D->getNextDeclarator()) |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 132 | Live.reset(AD[D]); |
Ted Kremenek | 27b07c5 | 2007-09-06 21:26:58 +0000 | [diff] [blame] | 133 | } |
Ted Kremenek | e4e6334 | 2007-09-06 00:17:54 +0000 | [diff] [blame] | 134 | } // end anonymous namespace |
| 135 | |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 136 | namespace { |
| 137 | struct Merge { |
| 138 | void operator()(LiveVariables::ValTy& Dst, LiveVariables::ValTy& Src) { |
| 139 | Src |= Dst; |
| 140 | } |
| 141 | }; |
| 142 | } // end anonymous namespace |
Ted Kremenek | e4e6334 | 2007-09-06 00:17:54 +0000 | [diff] [blame] | 143 | |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 144 | namespace { |
| 145 | typedef DataflowSolver<LiveVariables,TransferFuncs,Merge> Solver; |
Ted Kremenek | e4e6334 | 2007-09-06 00:17:54 +0000 | [diff] [blame] | 146 | } |
| 147 | |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 148 | void LiveVariables::runOnCFG(const CFG& cfg) { |
| 149 | Solver S(*this); |
| 150 | S.runOnCFG(cfg); |
| 151 | } |
Ted Kremenek | 27b07c5 | 2007-09-06 21:26:58 +0000 | [diff] [blame] | 152 | |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 153 | void LiveVariables::runOnAllBlocks(const CFG& cfg, |
| 154 | LiveVariables::ObserverTy& Obs) { |
| 155 | Solver S(*this); |
| 156 | ObserverTy* OldObserver = getAnalysisData().Observer; |
| 157 | getAnalysisData().Observer = &Obs; |
| 158 | S.runOnAllBlocks(cfg); |
| 159 | getAnalysisData().Observer = OldObserver; |
Ted Kremenek | 27b07c5 | 2007-09-06 21:26:58 +0000 | [diff] [blame] | 160 | } |
| 161 | |
| 162 | //===----------------------------------------------------------------------===// |
| 163 | // liveness queries |
| 164 | // |
| 165 | |
Ted Kremenek | c0576ca | 2007-09-10 17:36:42 +0000 | [diff] [blame] | 166 | bool LiveVariables::isLive(const CFGBlock* B, const VarDecl* D) const { |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 167 | return getBlockData(B)[ getAnalysisData()[D] ]; |
Ted Kremenek | 27b07c5 | 2007-09-06 21:26:58 +0000 | [diff] [blame] | 168 | } |
| 169 | |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 170 | bool LiveVariables::isLive(const ValTy& Live, const VarDecl* D) const { |
| 171 | return Live[ getAnalysisData()[D] ]; |
Ted Kremenek | 055c275 | 2007-09-06 23:00:42 +0000 | [diff] [blame] | 172 | } |
| 173 | |
Ted Kremenek | 055c275 | 2007-09-06 23:00:42 +0000 | [diff] [blame] | 174 | //===----------------------------------------------------------------------===// |
Ted Kremenek | e4e6334 | 2007-09-06 00:17:54 +0000 | [diff] [blame] | 175 | // printing liveness state for debugging |
| 176 | // |
| 177 | |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 178 | void LiveVariables::dumpLiveness(const ValTy& V, SourceManager& SM) const { |
| 179 | const AnalysisDataTy& AD = getAnalysisData(); |
| 180 | |
| 181 | for (AnalysisDataTy::iterator I = AD.begin(), E = AD.end(); I!=E; ++I) |
| 182 | if (V[I->second]) { |
Ted Kremenek | 27b07c5 | 2007-09-06 21:26:58 +0000 | [diff] [blame] | 183 | SourceLocation PhysLoc = SM.getPhysicalLoc(I->first->getLocation()); |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 184 | |
Ted Kremenek | 27b07c5 | 2007-09-06 21:26:58 +0000 | [diff] [blame] | 185 | fprintf(stderr, " %s <%s:%u:%u>\n", |
| 186 | I->first->getIdentifier()->getName(), |
| 187 | SM.getSourceName(PhysLoc), |
| 188 | SM.getLineNumber(PhysLoc), |
| 189 | SM.getColumnNumber(PhysLoc)); |
Ted Kremenek | e4e6334 | 2007-09-06 00:17:54 +0000 | [diff] [blame] | 190 | } |
Ted Kremenek | e4e6334 | 2007-09-06 00:17:54 +0000 | [diff] [blame] | 191 | } |
| 192 | |
Ted Kremenek | 27b07c5 | 2007-09-06 21:26:58 +0000 | [diff] [blame] | 193 | void LiveVariables::dumpBlockLiveness(SourceManager& M) const { |
Ted Kremenek | fdd225e | 2007-09-25 04:31:27 +0000 | [diff] [blame^] | 194 | for (BlockDataMapTy::iterator I = getBlockDataMap().begin(), |
| 195 | E = getBlockDataMap().end(); I!=E; ++I) { |
| 196 | fprintf(stderr, "\n[ B%d (live variables at block exit) ]\n", |
Ted Kremenek | 27b07c5 | 2007-09-06 21:26:58 +0000 | [diff] [blame] | 197 | I->first->getBlockID()); |
| 198 | |
| 199 | dumpLiveness(I->second,M); |
| 200 | } |
Ted Kremenek | c0576ca | 2007-09-10 17:36:42 +0000 | [diff] [blame] | 201 | |
| 202 | fprintf(stderr,"\n"); |
| 203 | } |