1 files changed, 139 insertions, 0 deletions
diff --git a/contrib/llvm-project/clang/lib/StaticAnalyzer/Checkers/BuiltinFunctionChecker.cpp b/contrib/llvm-project/clang/lib/StaticAnalyzer/Checkers/BuiltinFunctionChecker.cpp
new file mode 100644
index 000000000000..10594e331cbe
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+++ b/contrib/llvm-project/clang/lib/StaticAnalyzer/Checkers/BuiltinFunctionChecker.cpp
@@ -0,0 +1,139 @@
+//=== BuiltinFunctionChecker.cpp --------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This checker evaluates clang builtin functions.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
+#include "clang/Basic/Builtins.h"
+#include "clang/StaticAnalyzer/Core/Checker.h"
+#include "clang/StaticAnalyzer/Core/CheckerManager.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+
+using namespace clang;
+using namespace ento;
+
+namespace {
+
+class BuiltinFunctionChecker : public Checker<eval::Call> {
+public:
+  bool evalCall(const CallEvent &Call, CheckerContext &C) const;
+};
+
+}
+
+bool BuiltinFunctionChecker::evalCall(const CallEvent &Call,
+                                      CheckerContext &C) const {
+  ProgramStateRef state = C.getState();
+  const auto *FD = dyn_cast_or_null<FunctionDecl>(Call.getDecl());
+  if (!FD)
+    return false;
+
+  const LocationContext *LCtx = C.getLocationContext();
+  const Expr *CE = Call.getOriginExpr();
+
+  switch (FD->getBuiltinID()) {
+  default:
+    return false;
+
+  case Builtin::BI__builtin_assume: {
+    assert (Call.getNumArgs() > 0);
+    SVal Arg = Call.getArgSVal(0);
+    if (Arg.isUndef())
+      return true; // Return true to model purity.
+
+    state = state->assume(Arg.castAs<DefinedOrUnknownSVal>(), true);
+    // FIXME: do we want to warn here? Not right now. The most reports might
+    // come from infeasible paths, thus being false positives.
+    if (!state) {
+      C.generateSink(C.getState(), C.getPredecessor());
+      return true;
+    }
+
+    C.addTransition(state);
+    return true;
+  }
+
+  case Builtin::BI__builtin_unpredictable:
+  case Builtin::BI__builtin_expect:
+  case Builtin::BI__builtin_assume_aligned:
+  case Builtin::BI__builtin_addressof: {
+    // For __builtin_unpredictable, __builtin_expect, and
+    // __builtin_assume_aligned, just return the value of the subexpression.
+    // __builtin_addressof is going from a reference to a pointer, but those
+    // are represented the same way in the analyzer.
+    assert (Call.getNumArgs() > 0);
+    SVal Arg = Call.getArgSVal(0);
+    C.addTransition(state->BindExpr(CE, LCtx, Arg));
+    return true;
+  }
+
+  case Builtin::BI__builtin_alloca_with_align:
+  case Builtin::BI__builtin_alloca: {
+    // FIXME: Refactor into StoreManager itself?
+    MemRegionManager& RM = C.getStoreManager().getRegionManager();
+    const AllocaRegion* R =
+      RM.getAllocaRegion(CE, C.blockCount(), 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.
+    auto Size = Call.getArgSVal(0);
+    if (Size.isUndef())
+      return true; // Return true to model purity.
+
+    SValBuilder& svalBuilder = C.getSValBuilder();
+    DefinedOrUnknownSVal Extent = R->getExtent(svalBuilder);
+    DefinedOrUnknownSVal extentMatchesSizeArg =
+      svalBuilder.evalEQ(state, Extent, Size.castAs<DefinedOrUnknownSVal>());
+    state = state->assume(extentMatchesSizeArg, true);
+    assert(state && "The region should not have any previous constraints");
+
+    C.addTransition(state->BindExpr(CE, LCtx, loc::MemRegionVal(R)));
+    return true;
+  }
+
+  case Builtin::BI__builtin_dynamic_object_size:
+  case Builtin::BI__builtin_object_size:
+  case Builtin::BI__builtin_constant_p: {
+    // This must be resolvable at compile time, so we defer to the constant
+    // evaluator for a value.
+    SValBuilder &SVB = C.getSValBuilder();
+    SVal V = UnknownVal();
+    Expr::EvalResult EVResult;
+    if (CE->EvaluateAsInt(EVResult, C.getASTContext(), Expr::SE_NoSideEffects)) {
+      // Make sure the result has the correct type.
+      llvm::APSInt Result = EVResult.Val.getInt();
+      BasicValueFactory &BVF = SVB.getBasicValueFactory();
+      BVF.getAPSIntType(CE->getType()).apply(Result);
+      V = SVB.makeIntVal(Result);
+    }
+
+    if (FD->getBuiltinID() == Builtin::BI__builtin_constant_p) {
+      // If we didn't manage to figure out if the value is constant or not,
+      // it is safe to assume that it's not constant and unsafe to assume
+      // that it's constant.
+      if (V.isUnknown())
+        V = SVB.makeIntVal(0, CE->getType());
+    }
+
+    C.addTransition(state->BindExpr(CE, LCtx, V));
+    return true;
+  }
+  }
+}
+
+void ento::registerBuiltinFunctionChecker(CheckerManager &mgr) {
+  mgr.registerChecker<BuiltinFunctionChecker>();
+}
+
+bool ento::shouldRegisterBuiltinFunctionChecker(const LangOptions &LO) {
+  return true;
+}