1 files changed, 82 insertions, 0 deletions
diff --git a/clang/lib/StaticAnalyzer/Checkers/BuiltinFunctionChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/BuiltinFunctionChecker.cpp
new file mode 100644
index 0000000..509bc79
--- /dev/null
+++ b/clang/lib/StaticAnalyzer/Checkers/BuiltinFunctionChecker.cpp
@@ -0,0 +1,82 @@
+//=== BuiltinFunctionChecker.cpp --------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This checker evaluates clang builtin functions.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ClangSACheckers.h"
+#include "clang/StaticAnalyzer/Core/Checker.h"
+#include "clang/StaticAnalyzer/Core/CheckerManager.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+#include "clang/Basic/Builtins.h"
+
+using namespace clang;
+using namespace ento;
+
+namespace {
+
+class BuiltinFunctionChecker : public Checker<eval::Call> {
+public:
+  bool evalCall(const CallExpr *CE, CheckerContext &C) const;
+};
+
+}
+
+bool BuiltinFunctionChecker::evalCall(const CallExpr *CE,
+                                      CheckerContext &C) const {
+  ProgramStateRef state = C.getState();
+  const FunctionDecl *FD = C.getCalleeDecl(CE);
+  const LocationContext *LCtx = C.getLocationContext();
+  if (!FD)
+    return false;
+
+  unsigned id = FD->getBuiltinID();
+
+  if (!id)
+    return false;
+
+  switch (id) {
+  case Builtin::BI__builtin_expect: {
+    // For __builtin_expect, just return the value of the subexpression.
+    assert (CE->arg_begin() != CE->arg_end());
+    SVal X = state->getSVal(*(CE->arg_begin()), LCtx);
+    C.addTransition(state->BindExpr(CE, LCtx, X));
+    return true;
+  }
+
+  case Builtin::BI__builtin_alloca: {
+    // FIXME: Refactor into StoreManager itself?
+    MemRegionManager& RM = C.getStoreManager().getRegionManager();
+    const AllocaRegion* R =
+      RM.getAllocaRegion(CE, C.getCurrentBlockCount(), C.getLocationContext());
+
+    // Set the extent of the region in bytes. This enables us to use the
+    // SVal of the argument directly. If we save the extent in bits, we
+    // cannot represent values like symbol*8.
+    DefinedOrUnknownSVal Size =
+      cast<DefinedOrUnknownSVal>(state->getSVal(*(CE->arg_begin()), LCtx));
+
+    SValBuilder& svalBuilder = C.getSValBuilder();
+    DefinedOrUnknownSVal Extent = R->getExtent(svalBuilder);
+    DefinedOrUnknownSVal extentMatchesSizeArg =
+      svalBuilder.evalEQ(state, Extent, Size);
+    state = state->assume(extentMatchesSizeArg, true);
+
+    C.addTransition(state->BindExpr(CE, LCtx, loc::MemRegionVal(R)));
+    return true;
+  }
+  }
+
+  return false;
+}
+
+void ento::registerBuiltinFunctionChecker(CheckerManager &mgr) {
+  mgr.registerChecker<BuiltinFunctionChecker>();
+}