clang/lib/Analysis/CFGStmtMap.cpp

   1 //===--- CFGStmtMap.h - Map from Stmt* to CFGBlock* -----------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 //  This file defines the CFGStmtMap class, which defines a mapping from
  10 //  Stmt* to CFGBlock*
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/ADT/DenseMap.h"
  15 #include "clang/AST/ParentMap.h"
  16 #include "clang/Analysis/CFG.h"
  17 #include "clang/Analysis/CFGStmtMap.h"
  18 #include <optional>
  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 nullptr;
  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     std::optional<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->getTerminatorStmt())
  75     SM[Term] = B;
  76 }
  77
  78 CFGStmtMap *CFGStmtMap::Build(CFG *C, ParentMap *PM) {
  79   if (!C || !PM)
  80     return nullptr;
  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