1 //===- ControlFlowContext.cpp ---------------------------------------------===//
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 a ControlFlowContext class that is used by dataflow
10 //  analyses that run over Control-Flow Graphs (CFGs).
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "clang/Analysis/FlowSensitive/ControlFlowContext.h"
15 #include "clang/AST/ASTContext.h"
16 #include "clang/AST/Decl.h"
17 #include "clang/AST/Stmt.h"
18 #include "clang/Analysis/CFG.h"
19 #include "llvm/ADT/DenseMap.h"
20 #include "llvm/Support/Error.h"
21 #include <utility>
22 
23 namespace clang {
24 namespace dataflow {
25 
26 /// Returns a map from statements to basic blocks that contain them.
27 static llvm::DenseMap<const Stmt *, const CFGBlock *>
28 buildStmtToBasicBlockMap(const CFG &Cfg) {
29   llvm::DenseMap<const Stmt *, const CFGBlock *> StmtToBlock;
30   for (const CFGBlock *Block : Cfg) {
31     if (Block == nullptr)
32       continue;
33 
34     for (const CFGElement &Element : *Block) {
35       auto Stmt = Element.getAs<CFGStmt>();
36       if (!Stmt)
37         continue;
38 
39       StmtToBlock[Stmt.value().getStmt()] = Block;
40     }
41     if (const Stmt *TerminatorStmt = Block->getTerminatorStmt())
42       StmtToBlock[TerminatorStmt] = Block;
43   }
44   return StmtToBlock;
45 }
46 
47 llvm::Expected<ControlFlowContext>
48 ControlFlowContext::build(const Decl *D, Stmt *S, ASTContext *C) {
49   CFG::BuildOptions Options;
50   Options.PruneTriviallyFalseEdges = false;
51   Options.AddImplicitDtors = true;
52   Options.AddTemporaryDtors = true;
53   Options.AddInitializers = true;
54   Options.AddCXXDefaultInitExprInCtors = true;
55 
56   // Ensure that all sub-expressions in basic blocks are evaluated.
57   Options.setAllAlwaysAdd();
58 
59   auto Cfg = CFG::buildCFG(D, S, C, Options);
60   if (Cfg == nullptr)
61     return llvm::createStringError(
62         std::make_error_code(std::errc::invalid_argument),
63         "CFG::buildCFG failed");
64 
65   llvm::DenseMap<const Stmt *, const CFGBlock *> StmtToBlock =
66       buildStmtToBasicBlockMap(*Cfg);
67   return ControlFlowContext(std::move(Cfg), std::move(StmtToBlock));
68 }
69 
70 } // namespace dataflow
71 } // namespace clang
72