r291964 - PR31631: fix bad CFG (and bogus warnings) when an if-statement has an init-statement and has binary operator as its condition.

[Richard Smith via cfe-commits]

Author: rsmith
Date: Fri Jan 13 16:16:41 2017
New Revision: 291964

URL: http://llvm.org/viewvc/llvm-project?rev=291964&view=rev
Log:
PR31631: fix bad CFG (and bogus warnings) when an if-statement has an init-statement and has binary operator as its condition.

Modified:
    cfe/trunk/lib/Analysis/CFG.cpp
    cfe/trunk/test/SemaCXX/uninitialized.cpp

Modified: cfe/trunk/lib/Analysis/CFG.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Analysis/CFG.cpp?rev=291964&r1=291963&r2=291964&view=diff
==============================================================================
--- cfe/trunk/lib/Analysis/CFG.cpp (original)
+++ cfe/trunk/lib/Analysis/CFG.cpp Fri Jan 13 16:16:41 2017
@@ -2175,19 +2175,15 @@ CFGBlock *CFGBuilder::VisitIfStmt(IfStmt
   SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos);
 
   // Create local scope for C++17 if init-stmt if one exists.
-  if (Stmt *Init = I->getInit()) {
-    LocalScope::const_iterator BeginScopePos = ScopePos;
+  if (Stmt *Init = I->getInit())
     addLocalScopeForStmt(Init);
-    addAutomaticObjDtors(ScopePos, BeginScopePos, I);
-  }
 
   // Create local scope for possible condition variable.
   // Store scope position. Add implicit destructor.
-  if (VarDecl *VD = I->getConditionVariable()) {
-    LocalScope::const_iterator BeginScopePos = ScopePos;
+  if (VarDecl *VD = I->getConditionVariable())
     addLocalScopeForVarDecl(VD);
-    addAutomaticObjDtors(ScopePos, BeginScopePos, I);
-  }
+
+  addAutomaticObjDtors(ScopePos, save_scope_pos.get(), I);
 
   // The block we were processing is now finished.  Make it the successor
   // block.
@@ -2256,36 +2252,39 @@ CFGBlock *CFGBuilder::VisitIfStmt(IfStmt
   // removes infeasible paths from the control-flow graph by having the
   // control-flow transfer of '&&' or '||' go directly into the then/else
   // blocks directly.
-  if (!I->getConditionVariable())
-    if (BinaryOperator *Cond =
-            dyn_cast<BinaryOperator>(I->getCond()->IgnoreParens()))
-      if (Cond->isLogicalOp())
-        return VisitLogicalOperator(Cond, I, ThenBlock, ElseBlock).first;
-
-  // Now create a new block containing the if statement.
-  Block = createBlock(false);
+  BinaryOperator *Cond =
+      I->getConditionVariable()
+          ? nullptr
+          : dyn_cast<BinaryOperator>(I->getCond()->IgnoreParens());
+  CFGBlock *LastBlock;
+  if (Cond && Cond->isLogicalOp())
+    LastBlock = VisitLogicalOperator(Cond, I, ThenBlock, ElseBlock).first;
+  else {
+    // Now create a new block containing the if statement.
+    Block = createBlock(false);
 
-  // Set the terminator of the new block to the If statement.
-  Block->setTerminator(I);
+    // Set the terminator of the new block to the If statement.
+    Block->setTerminator(I);
 
-  // See if this is a known constant.
-  const TryResult &KnownVal = tryEvaluateBool(I->getCond());
+    // See if this is a known constant.
+    const TryResult &KnownVal = tryEvaluateBool(I->getCond());
 
-  // Add the successors.  If we know that specific branches are
-  // unreachable, inform addSuccessor() of that knowledge.
-  addSuccessor(Block, ThenBlock, /* isReachable = */ !KnownVal.isFalse());
-  addSuccessor(Block, ElseBlock, /* isReachable = */ !KnownVal.isTrue());
-
-  // Add the condition as the last statement in the new block.  This may create
-  // new blocks as the condition may contain control-flow.  Any newly created
-  // blocks will be pointed to be "Block".
-  CFGBlock *LastBlock = addStmt(I->getCond());
-
-  // If the IfStmt contains a condition variable, add it and its
-  // initializer to the CFG.
-  if (const DeclStmt* DS = I->getConditionVariableDeclStmt()) {
-    autoCreateBlock();
-    LastBlock = addStmt(const_cast<DeclStmt *>(DS));
+    // Add the successors.  If we know that specific branches are
+    // unreachable, inform addSuccessor() of that knowledge.
+    addSuccessor(Block, ThenBlock, /* isReachable = */ !KnownVal.isFalse());
+    addSuccessor(Block, ElseBlock, /* isReachable = */ !KnownVal.isTrue());
+
+    // Add the condition as the last statement in the new block.  This may
+    // create new blocks as the condition may contain control-flow.  Any newly
+    // created blocks will be pointed to be "Block".
+    LastBlock = addStmt(I->getCond());
+
+    // If the IfStmt contains a condition variable, add it and its
+    // initializer to the CFG.
+    if (const DeclStmt* DS = I->getConditionVariableDeclStmt()) {
+      autoCreateBlock();
+      LastBlock = addStmt(const_cast<DeclStmt *>(DS));
+    }
   }
 
   // Finally, if the IfStmt contains a C++17 init-stmt, add it to the CFG.
@@ -3078,19 +3077,15 @@ CFGBlock *CFGBuilder::VisitSwitchStmt(Sw
   SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos);
 
   // Create local scope for C++17 switch init-stmt if one exists.
-  if (Stmt *Init = Terminator->getInit()) {
-    LocalScope::const_iterator BeginScopePos = ScopePos;
+  if (Stmt *Init = Terminator->getInit())
     addLocalScopeForStmt(Init);
-    addAutomaticObjDtors(ScopePos, BeginScopePos, Terminator);
-  }
 
   // Create local scope for possible condition variable.
   // Store scope position. Add implicit destructor.
-  if (VarDecl *VD = Terminator->getConditionVariable()) {
-    LocalScope::const_iterator SwitchBeginScopePos = ScopePos;
+  if (VarDecl *VD = Terminator->getConditionVariable())
     addLocalScopeForVarDecl(VD);
-    addAutomaticObjDtors(ScopePos, SwitchBeginScopePos, Terminator);
-  }
+
+  addAutomaticObjDtors(ScopePos, save_scope_pos.get(), Terminator);
 
   if (Block) {
     if (badCFG)

Modified: cfe/trunk/test/SemaCXX/uninitialized.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/uninitialized.cpp?rev=291964&r1=291963&r2=291964&view=diff
==============================================================================
--- cfe/trunk/test/SemaCXX/uninitialized.cpp (original)
+++ cfe/trunk/test/SemaCXX/uninitialized.cpp Fri Jan 13 16:16:41 2017
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -fsyntax-only -Wall -Wuninitialized -Wno-unused-value -Wno-unused-lambda-capture -std=c++11 -verify %s
+// RUN: %clang_cc1 -fsyntax-only -Wall -Wuninitialized -Wno-unused-value -Wno-unused-lambda-capture -std=c++1z -verify %s
 
 // definitions for std::move
 namespace std {
@@ -1437,3 +1437,13 @@ void array_capture(bool b) {
     [fname]{};
   }
 }
+
+void if_switch_init_stmt(int k) {
+  if (int n = 0; (n == k || k > 5)) {}
+
+  if (int n; (n == k || k > 5)) {} // expected-warning {{uninitialized}} expected-note {{initialize}}
+
+  switch (int n = 0; (n == k || k > 5)) {} // expected-warning {{boolean}}
+
+  switch (int n; (n == k || k > 5)) {} // expected-warning {{uninitialized}} expected-note {{initialize}} expected-warning {{boolean}}
+}