Change subexpressions to be visited in the CFG from left-to-right.

This is a more natural order of evaluation, and it is very important
for visualization in the static analyzer.  Within Xcode, the arrows
will not jump from right to left, which looks very visually jarring.
It also provides a more natural location for dataflow-based diagnostics.

Along the way, we found a case in the analyzer diagnostics where we
needed to indicate that a variable was "captured" by a block.

-fsyntax-only timings on sqlite3.c show no visible performance change,
although this is just one test case.

Fixes <rdar://problem/13016513>

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@174447 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 52 insertions, 19 deletions

diff --git a/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp b/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp
index 3aa351527f..17dd772a68 100644
--- a/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp
+++ b/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp
@@ -433,42 +433,65 @@ PathDiagnosticPiece *FindLastStoreBRVisitor::VisitNode(const ExplodedNode *Succ,
   llvm::raw_svector_ostream os(sbuf);
 
   if (const PostStmt *PS = StoreSite->getLocationAs<PostStmt>()) {
-    if (const DeclStmt *DS = PS->getStmtAs<DeclStmt>()) {
-
-      if (const VarRegion *VR = dyn_cast<VarRegion>(R)) {
-        os << "Variable '" << *VR->getDecl() << "' ";
+    const Stmt *S = PS->getStmt();
+    const char *action = 0;
+    const DeclStmt *DS = dyn_cast<DeclStmt>(S);
+    const VarRegion *VR = dyn_cast<VarRegion>(R);
+
+    if (DS) {
+      action = "initialized to ";
+    } else if (isa<BlockExpr>(S)) {
+      action = "captured by block as ";
+      if (VR) {
+        // See if we can get the BlockVarRegion.
+        ProgramStateRef State = StoreSite->getState();
+        SVal V = State->getSVal(S, PS->getLocationContext());
+        if (const BlockDataRegion *BDR =
+              dyn_cast_or_null<BlockDataRegion>(V.getAsRegion())) {
+          if (const VarRegion *OriginalR = BDR->getOriginalRegion(VR)) {
+            V = State->getSVal(OriginalR);
+            BR.addVisitor(new FindLastStoreBRVisitor(V, OriginalR));
+          }
+        }
       }
-      else
-        return NULL;
+    }
+
+    if (action) {
+      if (!R)
+        return 0;
+
+      os << "Variable '" << *VR->getDecl() << "' ";
 
       if (isa<loc::ConcreteInt>(V)) {
         bool b = false;
         if (R->isBoundable()) {
           if (const TypedValueRegion *TR = dyn_cast<TypedValueRegion>(R)) {
             if (TR->getValueType()->isObjCObjectPointerType()) {
-              os << "initialized to nil";
+              os << action << "nil";
               b = true;
             }
           }
         }
 
         if (!b)
-          os << "initialized to a null pointer value";
+          os << action << "a null pointer value";
       }
       else if (isa<nonloc::ConcreteInt>(V)) {
-        os << "initialized to " << cast<nonloc::ConcreteInt>(V).getValue();
+        os << action << cast<nonloc::ConcreteInt>(V).getValue();
       }
-      else if (V.isUndef()) {
-        if (isa<VarRegion>(R)) {
-          const VarDecl *VD = cast<VarDecl>(DS->getSingleDecl());
-          if (VD->getInit())
-            os << "initialized to a garbage value";
-          else
-            os << "declared without an initial value";
+      else if (DS) {
+        if (V.isUndef()) {
+          if (isa<VarRegion>(R)) {
+            const VarDecl *VD = cast<VarDecl>(DS->getSingleDecl());
+            if (VD->getInit())
+              os << "initialized to a garbage value";
+            else
+              os << "declared without an initial value";
+          }
+        }
+        else {
+          os << "initialized here";
         }
-      }
-      else {
-        os << "initialized here";
       }
     }
   } else if (isa<CallEnter>(StoreSite->getLocation())) {
diff --git a/lib/StaticAnalyzer/Core/MemRegion.cpp b/lib/StaticAnalyzer/Core/MemRegion.cpp
index 70bb965859..687c7c0188 100644
--- a/lib/StaticAnalyzer/Core/MemRegion.cpp
+++ b/lib/StaticAnalyzer/Core/MemRegion.cpp
@@ -1302,3 +1302,13 @@ BlockDataRegion::referenced_vars_end() const {
   return BlockDataRegion::referenced_vars_iterator(Vec->end(),
                                                    VecOriginal->end());
 }
+
+const VarRegion *BlockDataRegion::getOriginalRegion(const VarRegion *R) const {
+  for (referenced_vars_iterator I = referenced_vars_begin(),
+                                E = referenced_vars_end();
+       I != E; ++I) {
+    if (I.getCapturedRegion() == R)
+      return I.getOriginalRegion();
+  }
+  return 0;
+}