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      1 //===--- CFGStmtMap.h - Map from Stmt* to CFGBlock* -----------*- C++ -*-===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 //  This file defines the CFGStmtMap class, which defines a mapping from
     11 //  Stmt* to CFGBlock*
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #include "llvm/ADT/DenseMap.h"
     16 #include "clang/AST/ParentMap.h"
     17 #include "clang/Analysis/CFG.h"
     18 #include "clang/Analysis/CFGStmtMap.h"
     19 
     20 using namespace clang;
     21 
     22 typedef llvm::DenseMap<const Stmt*, CFGBlock*> SMap;
     23 static SMap *AsMap(void *m) { return (SMap*) m; }
     24 
     25 CFGStmtMap::~CFGStmtMap() { delete AsMap(M); }
     26 
     27 CFGBlock *CFGStmtMap::getBlock(Stmt *S) {
     28   SMap *SM = AsMap(M);
     29   Stmt *X = S;
     30 
     31   // If 'S' isn't in the map, walk the ParentMap to see if one of its ancestors
     32   // is in the map.
     33   while (X) {
     34     SMap::iterator I = SM->find(X);
     35     if (I != SM->end()) {
     36       CFGBlock *B = I->second;
     37       // Memoize this lookup.
     38       if (X != S)
     39         (*SM)[X] = B;
     40       return B;
     41     }
     42 
     43     X = PM->getParentIgnoreParens(X);
     44   }
     45 
     46   return 0;
     47 }
     48 
     49 static void Accumulate(SMap &SM, CFGBlock *B) {
     50   // First walk the block-level expressions.
     51   for (CFGBlock::iterator I = B->begin(), E = B->end(); I != E; ++I) {
     52     const CFGElement &CE = *I;
     53     const CFGStmt *CS = CE.getAs<CFGStmt>();
     54     if (!CS)
     55       continue;
     56 
     57     CFGBlock *&Entry = SM[CS->getStmt()];
     58     // If 'Entry' is already initialized (e.g., a terminator was already),
     59     // skip.
     60     if (Entry)
     61       continue;
     62 
     63     Entry = B;
     64 
     65   }
     66 
     67   // Look at the label of the block.
     68   if (Stmt *Label = B->getLabel())
     69     SM[Label] = B;
     70 
     71   // Finally, look at the terminator.  If the terminator was already added
     72   // because it is a block-level expression in another block, overwrite
     73   // that mapping.
     74   if (Stmt *Term = B->getTerminator())
     75     SM[Term] = B;
     76 }
     77 
     78 CFGStmtMap *CFGStmtMap::Build(CFG *C, ParentMap *PM) {
     79   if (!C || !PM)
     80     return 0;
     81 
     82   SMap *SM = new SMap();
     83 
     84   // Walk all blocks, accumulating the block-level expressions, labels,
     85   // and terminators.
     86   for (CFG::iterator I = C->begin(), E = C->end(); I != E; ++I)
     87     Accumulate(*SM, *I);
     88 
     89   return new CFGStmtMap(PM, SM);
     90 }
     91 
     92