[cfe-commits] r139593 - in /cfe/trunk: include/clang/Analysis/CFG.h lib/Analysis/CFG.cpp

[Chandler Carruth]

Author: chandlerc
Date: Tue Sep 13 04:53:55 2011
New Revision: 139593

URL: http://llvm.org/viewvc/llvm-project?rev=139593&view=rev
Log:
Add a bit to the CFGBlock to track when it contains a no-return
CFGElement. This will allow greatly simplifying the logic in
-Wreturn-type.

Modified:
    cfe/trunk/include/clang/Analysis/CFG.h
    cfe/trunk/lib/Analysis/CFG.cpp

Modified: cfe/trunk/include/clang/Analysis/CFG.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Analysis/CFG.h?rev=139593&r1=139592&r2=139593&view=diff
==============================================================================
--- cfe/trunk/include/clang/Analysis/CFG.h (original)
+++ cfe/trunk/include/clang/Analysis/CFG.h Tue Sep 13 04:53:55 2011
@@ -333,10 +333,21 @@
   AdjacentBlocks Preds;
   AdjacentBlocks Succs;
 
+  /// NoReturn - This bit is set when the basic block contains a function call
+  /// or implicit destructor that is attributed as 'noreturn'. In that case,
+  /// control cannot technically ever proceed past this block. All such blocks
+  /// will have a single immediate successor: the exit block. This allows them
+  /// to be easily reached from the exit block and using this bit quickly
+  /// recognized without scanning the contents of the block.
+  ///
+  /// Optimization Note: This bit could be profitably folded with Terminator's
+  /// storage if the memory usage of CFGBlock becomes an issue.
+  unsigned HasNoReturnElement : 1;
+
 public:
   explicit CFGBlock(unsigned blockid, BumpVectorContext &C)
     : Elements(C), Label(NULL), Terminator(NULL), LoopTarget(NULL),
-      BlockID(blockid), Preds(C, 1), Succs(C, 1) {}
+      BlockID(blockid), Preds(C, 1), Succs(C, 1), HasNoReturnElement(false) {}
   ~CFGBlock() {}
 
   // Statement iterators
@@ -458,6 +469,7 @@
   void setTerminator(Stmt *Statement) { Terminator = Statement; }
   void setLabel(Stmt *Statement) { Label = Statement; }
   void setLoopTarget(const Stmt *loopTarget) { LoopTarget = loopTarget; }
+  void setHasNoReturnElement() { HasNoReturnElement = true; }
 
   CFGTerminator getTerminator() { return Terminator; }
   const CFGTerminator getTerminator() const { return Terminator; }
@@ -473,6 +485,8 @@
   Stmt *getLabel() { return Label; }
   const Stmt *getLabel() const { return Label; }
 
+  bool hasNoReturnElement() const { return HasNoReturnElement; }
+
   unsigned getBlockID() const { return BlockID; }
 
   void dump(const CFG *cfg, const LangOptions &LO) const;

Modified: cfe/trunk/lib/Analysis/CFG.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Analysis/CFG.cpp?rev=139593&r1=139592&r2=139593&view=diff
==============================================================================
--- cfe/trunk/lib/Analysis/CFG.cpp (original)
+++ cfe/trunk/lib/Analysis/CFG.cpp Tue Sep 13 04:53:55 2011
@@ -603,6 +603,7 @@
 /// directly tied to the exit block in order to be reachable.
 CFGBlock *CFGBuilder::createNoReturnBlock() {
   CFGBlock *B = createBlock(false);
+  B->setHasNoReturnElement();
   addSuccessor(B, &cfg->getExit());
   return B;
 }