[cfe-commits] r159620 - in /cfe/trunk: lib/Analysis/UninitializedValues.cpp test/Sema/uninit-variables.c

[Richard Smith]

Author: rsmith
Date: Mon Jul  2 18:23:04 2012
New Revision: 159620

URL: http://llvm.org/viewvc/llvm-project?rev=159620&view=rev
Log:
-Wuninitialized: assume that an __attribute__((returns_twice)) function might
initialize any variable. This is extremely conservative, but is sufficient for
now.

Modified:
    cfe/trunk/lib/Analysis/UninitializedValues.cpp
    cfe/trunk/test/Sema/uninit-variables.c

Modified: cfe/trunk/lib/Analysis/UninitializedValues.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Analysis/UninitializedValues.cpp?rev=159620&r1=159619&r2=159620&view=diff
==============================================================================
--- cfe/trunk/lib/Analysis/UninitializedValues.cpp (original)
+++ cfe/trunk/lib/Analysis/UninitializedValues.cpp Mon Jul  2 18:23:04 2012
@@ -116,6 +116,7 @@
 
   BVPair &getValueVectors(const CFGBlock *block, bool shouldLazyCreate);
 
+  void setAllScratchValues(Value V);
   void mergeIntoScratch(ValueVector const &source, bool isFirst);
   bool updateValueVectorWithScratch(const CFGBlock *block);
   bool updateValueVectors(const CFGBlock *block, const BVPair &newVals);
@@ -240,6 +241,11 @@
 }
 #endif
 
+void CFGBlockValues::setAllScratchValues(Value V) {
+  for (unsigned I = 0, E = scratch.size(); I != E; ++I)
+    scratch[I] = V;
+}
+
 void CFGBlockValues::mergeIntoScratch(ValueVector const &source,
                                       bool isFirst) {
   if (isFirst)
@@ -374,6 +380,7 @@
   void reportUse(const Expr *ex, const VarDecl *vd);
 
   void VisitBlockExpr(BlockExpr *be);
+  void VisitCallExpr(CallExpr *ce);
   void VisitDeclStmt(DeclStmt *ds);
   void VisitDeclRefExpr(DeclRefExpr *dr);
   void VisitUnaryOperator(UnaryOperator *uo);
@@ -576,6 +583,17 @@
   }
 }
 
+void TransferFunctions::VisitCallExpr(CallExpr *ce) {
+  // After a call to a function like setjmp or vfork, any variable which is
+  // initialized anywhere within this function may now be initialized. For now,
+  // just assume such a call initializes all variables.
+  // FIXME: Only mark variables as initialized if they have an initializer which
+  // is reachable from here.
+  Decl *Callee = ce->getCalleeDecl();
+  if (Callee && Callee->hasAttr<ReturnsTwiceAttr>())
+    vals.setAllScratchValues(Initialized);
+}
+
 void TransferFunctions::VisitDeclRefExpr(DeclRefExpr *dr) {
   // Record the last DeclRefExpr seen.  This is an lvalue computation.
   // We use this value to later detect if a variable "escapes" the analysis.

Modified: cfe/trunk/test/Sema/uninit-variables.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/uninit-variables.c?rev=159620&r1=159619&r2=159620&view=diff
==============================================================================
--- cfe/trunk/test/Sema/uninit-variables.c (original)
+++ cfe/trunk/test/Sema/uninit-variables.c Mon Jul  2 18:23:04 2012
@@ -466,3 +466,22 @@
     k = produce();
   }
 }
+
+typedef char jmp_buf[256];
+extern int setjmp(jmp_buf env); // implicitly returns_twice
+
+void do_stuff_and_longjmp(jmp_buf env, int *result) __attribute__((noreturn));
+
+int returns_twice() {
+  int a; // expected-note {{initialize}}
+  if (!a) { // expected-warning {{variable 'a' is uninitialized}}
+    jmp_buf env;
+    int b;
+    if (setjmp(env) == 0) {
+      do_stuff_and_longjmp(env, &b);
+    } else {
+      a = b; // no warning
+    }
+  }
+  return a;
+}