vsavchenko created this revision.
vsavchenko added reviewers: NoQ, xazax.hun, martong, steakhal, Szelethus,
ASDenysPetrov, manas, RedDocMD.
Herald added subscribers: dkrupp, donat.nagy, mikhail.ramalho, a.sidorin,
rnkovacs, szepet, baloghadamsoftware.
vsavchenko requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.
rdar://76948312
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D104716
Files:
clang/lib/StaticAnalyzer/Core/CallEvent.cpp
clang/test/Analysis/transparent_union_bug.c
Index: clang/test/Analysis/transparent_union_bug.c
===================================================================
--- /dev/null
+++ clang/test/Analysis/transparent_union_bug.c
@@ -0,0 +1,42 @@
+// RUN: %clang_analyze_cc1 -analyze -triple x86_64-apple-darwin10 \
+// RUN: -analyzer-checker=core,debug.ExprInspection -verify %s
+
+void clang_analyzer_warnIfReached();
+void clang_analyzer_printState();
+
+typedef struct {
+ int value;
+} Struct;
+
+typedef union {
+ Struct *ptr;
+ long num;
+} __attribute__((transparent_union)) Alias;
+
+void foo(Struct *x);
+void foo(Alias y) {
+ if (y.ptr == 0) {
+ // no-crash
+ }
+ clang_analyzer_warnIfReached(); // expected-warning{{REACHABLE}}
+}
+void foobar(long z);
+void foobar(Alias z) {
+ clang_analyzer_printState();
+ if (z.num != 42) {
+ // no-crash
+ }
+ clang_analyzer_warnIfReached(); // expected-warning{{REACHABLE}}
+}
+
+void foobaz(Alias x) {
+ if (x.ptr == 0) {
+ // no-crash
+ }
+ clang_analyzer_warnIfReached(); // expected-warning{{REACHABLE}}
+}
+void bar(Struct arg) {
+ foo(&arg);
+ foobar(42);
+ foobaz(&arg);
+}
Index: clang/lib/StaticAnalyzer/Core/CallEvent.cpp
===================================================================
--- clang/lib/StaticAnalyzer/Core/CallEvent.cpp
+++ clang/lib/StaticAnalyzer/Core/CallEvent.cpp
@@ -47,6 +47,7 @@
#include "clang/StaticAnalyzer/Core/PathSensitive/Store.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/ImmutableList.h"
#include "llvm/ADT/None.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/PointerIntPair.h"
@@ -466,6 +467,46 @@
llvm_unreachable("unknown callable kind");
}
+static bool isTransparentUnion(QualType T) {
+ const RecordType *UT = T->getAsUnionType();
+ return UT && UT->getDecl()->hasAttr<TransparentUnionAttr>();
+}
+
+static bool isTransparentUnion(SVal Value, const ASTContext &Context) {
+ Optional<QualType> T = Value.getType(Context);
+ return T && isTransparentUnion(*T);
+}
+
+// In some cases, symbolic cases should be transformed before we associate
+// them with parameters. This function incapsulates such cases.
+static SVal process(SVal Value, const ParmVarDecl *Parameter,
+ SValBuilder &SVB) {
+ QualType ParamType = Parameter->getType();
+
+ // Transparent unions allow users to easily convert values of union field
+ // types into union-typed objects.
+ //
+ // Also, more importantly, they allow users to define functions with different
+ // different parameter types, substituting types matching transparent union
+ // field types with the union type itself.
+ //
+ // Here, we check specifically for latter cases and prevent binding
+ // field-typed values to union-typed regions.
+ if (isTransparentUnion(ParamType) &&
+ // Let's check that we indeed trying to bind different types.
+ !isTransparentUnion(Value, SVB.getContext())) {
+ BasicValueFactory &BVF = SVB.getBasicValueFactory();
+
+ llvm::ImmutableList<SVal> CompoundSVals = BVF.getEmptySValList();
+ CompoundSVals = BVF.prependSVal(Value, CompoundSVals);
+
+ // Wrap it with compound value.
+ return SVB.makeCompoundVal(ParamType, CompoundSVals);
+ }
+
+ return Value;
+}
+
static void addParameterValuesToBindings(const StackFrameContext *CalleeCtx,
CallEvent::BindingsTy &Bindings,
SValBuilder &SVB,
@@ -493,7 +534,7 @@
if (!ArgVal.isUnknown()) {
Loc ParamLoc = SVB.makeLoc(
MRMgr.getParamVarRegion(Call.getOriginExpr(), Idx, CalleeCtx));
- Bindings.push_back(std::make_pair(ParamLoc, ArgVal));
+ Bindings.push_back(std::make_pair(ParamLoc, process(ArgVal, *I, SVB)));
}
}
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