Implement faux-body-synthesis of well-known functions in the static analyzer when

their implementations are unavailable.  Start by simulating dispatch_sync().

This change is largely a bunch of plumbing around something very simple.  We
use AnalysisDeclContext to conjure up a fake function body (using the
current ASTContext) when one does not exist.  This is controlled
under the analyzer-config option "faux-bodies", which is off by default.

The plumbing in this patch is largely to pass the necessary machinery
around.  CallEvent needs the AnalysisDeclContextManager to get
the function definition, as one may get conjured up lazily.

BugReporter and PathDiagnosticLocation needed to be relaxed to handle
invalid locations, as the conjured body has no real source locations.
We do some primitive recovery in diagnostic generation to generate
some reasonable locations (for arrows and events), but it can be
improved.

llvm-svn: 164339

1 files changed, 25 insertions, 6 deletions

diff --git a/clang/lib/Analysis/AnalysisDeclContext.cpp b/clang/lib/Analysis/AnalysisDeclContext.cpp
index f2ef0de..a4bf8d1 100644
--- a/clang/lib/Analysis/AnalysisDeclContext.cpp
+++ b/clang/lib/Analysis/AnalysisDeclContext.cpp
@@ -29,13 +29,15 @@
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/Support/ErrorHandling.h"
 
+#include "BodyFarm.h"
+
 using namespace clang;
 
 typedef llvm::DenseMap<const void *, ManagedAnalysis *> ManagedAnalysisMap;
 
 AnalysisDeclContext::AnalysisDeclContext(AnalysisDeclContextManager *Mgr,
-                                 const Decl *d,
-                                 const CFG::BuildOptions &buildOptions)
+                                         const Decl *d,
+                                         const CFG::BuildOptions &buildOptions)
   : Manager(Mgr),
     D(d),
     cfgBuildOptions(buildOptions),
@@ -49,7 +51,7 @@ AnalysisDeclContext::AnalysisDeclContext(AnalysisDeclContextManager *Mgr,
 }
 
 AnalysisDeclContext::AnalysisDeclContext(AnalysisDeclContextManager *Mgr,
-                                 const Decl *d)
+                                         const Decl *d)
 : Manager(Mgr),
   D(d),
   forcedBlkExprs(0),
@@ -64,7 +66,10 @@ AnalysisDeclContext::AnalysisDeclContext(AnalysisDeclContextManager *Mgr,
 AnalysisDeclContextManager::AnalysisDeclContextManager(bool useUnoptimizedCFG,
                                                        bool addImplicitDtors,
                                                        bool addInitializers,
-                                                       bool addTemporaryDtors) {
+                                                       bool addTemporaryDtors,
+                                                       bool synthesizeBodies)
+  : SynthesizeBodies(synthesizeBodies)
+{
   cfgBuildOptions.PruneTriviallyFalseEdges = !useUnoptimizedCFG;
   cfgBuildOptions.AddImplicitDtors = addImplicitDtors;
   cfgBuildOptions.AddInitializers = addInitializers;
@@ -77,9 +82,18 @@ void AnalysisDeclContextManager::clear() {
   Contexts.clear();
 }
 
+static BodyFarm &getBodyFarm(ASTContext &C) {
+  static BodyFarm *BF = new BodyFarm(C);
+  return *BF;
+}
+
 Stmt *AnalysisDeclContext::getBody() const {
-  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D))
-    return FD->getBody();
+  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
+    Stmt *Body = FD->getBody();
+    if (!Body && Manager && Manager->synthesizeBodies())
+      return getBodyFarm(getASTContext()).getBody(FD);
+    return Body;
+  }
   else if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D))
     return MD->getBody();
   else if (const BlockDecl *BD = dyn_cast<BlockDecl>(D))
@@ -203,6 +217,11 @@ PseudoConstantAnalysis *AnalysisDeclContext::getPseudoConstantAnalysis() {
 }
 
 AnalysisDeclContext *AnalysisDeclContextManager::getContext(const Decl *D) {
+  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
+    FD->hasBody(FD);
+    D = FD;
+  }
+
   AnalysisDeclContext *&AC = Contexts[D];
   if (!AC)
     AC = new AnalysisDeclContext(this, D, cfgBuildOptions);