From: Kristof Umann <dkszelethus@gmail.com>
Date: Wed, 3 Jul 2019 12:53:19 +0000 (+0000)
Subject: [analyzer][CFG] Return the correct terminator condition
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=d6dbda40c8398a217b4f482c4e68e337a00029c3;p=clang

[analyzer][CFG] Return the correct terminator condition

For the following terminator statement:

if (A && B && C && D)
The built CFG is the following:

[B5 (ENTRY)]
  Succs (1): B4

[B1]
  1: 10
  2: j
  3: [B1.2] (ImplicitCastExpr, LValueToRValue, int)
  4: [B1.1] / [B1.3]
  5: int x = 10 / j;
  Preds (1): B2
  Succs (1): B0

[B2]
  1: C
  2: [B2.1] (ImplicitCastExpr, LValueToRValue, _Bool)
  T: if [B4.4] && [B3.2] && [B2.2]
  Preds (1): B3
  Succs (2): B1 B0

[B3]
  1: B
  2: [B3.1] (ImplicitCastExpr, LValueToRValue, _Bool)
  T: [B4.4] && [B3.2] && ...
  Preds (1): B4
  Succs (2): B2 B0

[B4]
  1: 0
  2: int j = 0;
  3: A
  4: [B4.3] (ImplicitCastExpr, LValueToRValue, _Bool)
  T: [B4.4] && ...
  Preds (1): B5
  Succs (2): B3 B0

[B0 (EXIT)]
  Preds (4): B1 B2 B3 B4

However, even though the path of execution in B2 only depends on C's value,
CFGBlock::getCondition() would return the entire condition (A && B && C). For
B3, it would return A && B. I changed this the actual condition.

Differential Revision: https://reviews.llvm.org/D63538

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@365036 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/include/clang/Analysis/CFG.h b/include/clang/Analysis/CFG.h
index d8b3d6ff71..945d36498c 100644
--- a/include/clang/Analysis/CFG.h
+++ b/include/clang/Analysis/CFG.h
@@ -860,10 +860,12 @@ public:
   Stmt *getTerminatorStmt() { return Terminator.getStmt(); }
   const Stmt *getTerminatorStmt() const { return Terminator.getStmt(); }
 
-  Stmt *getTerminatorCondition(bool StripParens = true);
+  /// \returns the condition of the terminator (condition of an if statement,
+  /// for loop, etc).
+  const Stmt *getTerminatorCondition(bool StripParens = true) const;
 
-  const Stmt *getTerminatorCondition(bool StripParens = true) const {
-    return const_cast<CFGBlock*>(this)->getTerminatorCondition(StripParens);
+  const Expr *getTerminatorConditionExpr(bool StripParens = true) const {
+    return dyn_cast_or_null<Expr>(getTerminatorCondition(StripParens));
   }
 
   const Stmt *getLoopTarget() const { return LoopTarget; }
diff --git a/lib/Analysis/CFG.cpp b/lib/Analysis/CFG.cpp
index b53bfcca37..3e6185c76c 100644
--- a/lib/Analysis/CFG.cpp
+++ b/lib/Analysis/CFG.cpp
@@ -5615,69 +5615,21 @@ void CFGBlock::printTerminatorJson(raw_ostream &Out, const LangOptions &LO,
   Out << JsonFormat(TempOut.str(), AddQuotes);
 }
 
-Stmt *CFGBlock::getTerminatorCondition(bool StripParens) {
-  Stmt *Terminator = getTerminatorStmt();
-  if (!Terminator)
+const Stmt *CFGBlock::getTerminatorCondition(bool StripParens) const {
+  // If the terminator is a temporary dtor or a virtual base, etc, we can't
+  // retrieve a meaningful condition, bail out.
+  if (rbegin()->getKind() != CFGElement::Kind::Statement)
     return nullptr;
 
-  Expr *E = nullptr;
-
-  switch (Terminator->getStmtClass()) {
-    default:
-      break;
-
-    case Stmt::CXXForRangeStmtClass:
-      E = cast<CXXForRangeStmt>(Terminator)->getCond();
-      break;
-
-    case Stmt::ForStmtClass:
-      E = cast<ForStmt>(Terminator)->getCond();
-      break;
-
-    case Stmt::WhileStmtClass:
-      E = cast<WhileStmt>(Terminator)->getCond();
-      break;
-
-    case Stmt::DoStmtClass:
-      E = cast<DoStmt>(Terminator)->getCond();
-      break;
-
-    case Stmt::IfStmtClass:
-      E = cast<IfStmt>(Terminator)->getCond();
-      break;
-
-    case Stmt::ChooseExprClass:
-      E = cast<ChooseExpr>(Terminator)->getCond();
-      break;
-
-    case Stmt::IndirectGotoStmtClass:
-      E = cast<IndirectGotoStmt>(Terminator)->getTarget();
-      break;
-
-    case Stmt::SwitchStmtClass:
-      E = cast<SwitchStmt>(Terminator)->getCond();
-      break;
-
-    case Stmt::BinaryConditionalOperatorClass:
-      E = cast<BinaryConditionalOperator>(Terminator)->getCond();
-      break;
-
-    case Stmt::ConditionalOperatorClass:
-      E = cast<ConditionalOperator>(Terminator)->getCond();
-      break;
-
-    case Stmt::BinaryOperatorClass: // '&&' and '||'
-      E = cast<BinaryOperator>(Terminator)->getLHS();
-      break;
-
-    case Stmt::ObjCForCollectionStmtClass:
-      return Terminator;
+  // This should be the condition of the terminator block.
+  const Stmt *S = rbegin()->castAs<CFGStmt>().getStmt();
+  if (isa<ObjCForCollectionStmt>(S)) {
+    return getTerminatorStmt();
   }
 
-  if (!StripParens)
-    return E;
-
-  return E ? E->IgnoreParens() : nullptr;
+  // Only ObjCForCollectionStmt is known not to be a non-Expr terminator.
+  const Expr *Cond = cast<Expr>(S);
+  return StripParens ? Cond->IgnoreParens() : Cond;
 }
 
 //===----------------------------------------------------------------------===//