Revert "[analyzer] Treat all struct values as regions (even rvalues)."

This turned out to have many implications, but what eventually seemed to
make it unworkable was the fact that we can get struct values (as
LazyCompoundVals) from other places besides return-by-value function calls;
that is, we weren't actually able to "treat all struct values as regions"
consistently across the entire analyzer core.

Hopefully we'll be able to come up with an alternate solution soon.

This reverts r163066 / 02df4f0aef142f00d4637cd851e54da2a123ca8e.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@163218 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/StaticAnalyzer/Core/PathSensitive/BasicValueFactory.h b/include/clang/StaticAnalyzer/Core/PathSensitive/BasicValueFactory.h
index 94c2015..fb39354 100644
--- a/include/clang/StaticAnalyzer/Core/PathSensitive/BasicValueFactory.h
+++ b/include/clang/StaticAnalyzer/Core/PathSensitive/BasicValueFactory.h
@@ -93,9 +93,6 @@
   /// Returns the type of the APSInt used to store values of the given QualType.
   APSIntType getAPSIntType(QualType T) const {
     assert(T->isIntegerType() || Loc::isLocType(T));
-    // Make sure all locations have the same representation in the analyzer.
-    if (Loc::isLocType(T))
-      T = Ctx.VoidPtrTy;
     return APSIntType(Ctx.getTypeSize(T),
                       !T->isSignedIntegerOrEnumerationType());
   }
diff --git a/include/clang/StaticAnalyzer/Core/PathSensitive/SVals.h b/include/clang/StaticAnalyzer/Core/PathSensitive/SVals.h
index 52e52e0..e0b5f64 100644
--- a/include/clang/StaticAnalyzer/Core/PathSensitive/SVals.h
+++ b/include/clang/StaticAnalyzer/Core/PathSensitive/SVals.h
@@ -246,16 +246,8 @@
   }
 
   static inline bool isLocType(QualType T) {
-    // Why are record types included here? Because we want to make sure a
-    // record, even a record rvalue, is always represented with a region.
-    // This is especially necessary in C++, where you can call methods on
-    // struct prvalues, which then need to have a valid 'this' pointer.
-    //
-    // This necessitates a bit of extra hackery in the Store to deal with
-    // the case of binding a "struct value" into a struct region; in
-    // practice it just means "dereferencing" the value before binding.
     return T->isAnyPointerType() || T->isBlockPointerType() || 
-           T->isReferenceType() || T->isRecordType();
+           T->isReferenceType();
   }
 };
 
diff --git a/lib/StaticAnalyzer/Core/RegionStore.cpp b/lib/StaticAnalyzer/Core/RegionStore.cpp
index 9634226..b3cf208 100644
--- a/lib/StaticAnalyzer/Core/RegionStore.cpp
+++ b/lib/StaticAnalyzer/Core/RegionStore.cpp
@@ -1744,26 +1744,6 @@
   if (!RD->isCompleteDefinition())
     return StoreRef(store, *this);
 
-  // Handle Loc values by automatically dereferencing the location.
-  // This is necessary because we treat all struct values as regions even if
-  // they are rvalues; we may then be asked to bind one of these
-  // "rvalue regions" to an actual struct region.
-  // (This is necessary for many of the test cases in array-struct-region.cpp.)
-  //
-  // This also handles the case of a struct argument passed by value to an
-  // inlined function. In this case, the C++ standard says that the value
-  // is copy-constructed into the parameter variable. However, the copy-
-  // constructor is processed before we actually know if we're going to inline
-  // the function, and thus we don't actually have the parameter's region
-  // available. Instead, we use a temporary-object region, then copy the
-  // bindings over by value.
-  //
-  // FIXME: This will be a problem when we handle the destructors of
-  // temporaries; the inlined function will modify the parameter region,
-  // but the destructor will act on the temporary region.
-  if (const loc::MemRegionVal *MRV = dyn_cast<loc::MemRegionVal>(&V))
-    V = getBinding(store, *MRV);
-
   // Handle lazy compound values and symbolic values.
   if (isa<nonloc::LazyCompoundVal>(V) || isa<nonloc::SymbolVal>(V))
     return BindAggregate(store, R, V);
diff --git a/lib/StaticAnalyzer/Core/SymbolManager.cpp b/lib/StaticAnalyzer/Core/SymbolManager.cpp
index 65356a9..c21df4c 100644
--- a/lib/StaticAnalyzer/Core/SymbolManager.cpp
+++ b/lib/StaticAnalyzer/Core/SymbolManager.cpp
@@ -365,6 +365,9 @@
   if (T->isIntegerType())
     return T->isScalarType();
 
+  if (T->isRecordType() && !T->isUnionType())
+    return true;
+
   return false;
 }
 
diff --git a/test/Analysis/array-struct-region.cpp b/test/Analysis/array-struct-region.cpp
deleted file mode 100644
index 3581566..0000000
--- a/test/Analysis/array-struct-region.cpp
+++ /dev/null
@@ -1,87 +0,0 @@
-// RUN: %clang_cc1 -analyze -analyzer-checker=core,alpha.core,debug.ExprInspection -verify -x c %s
-// RUN: %clang_cc1 -analyze -analyzer-checker=core,alpha.core,debug.ExprInspection -verify -x c++ -analyzer-config c++-inlining=constructors %s
-
-void clang_analyzer_eval(int);
-
-struct S {
-  int field;
-
-#if __cplusplus
-  const struct S *getThis() const { return this; }
-#endif
-};
-
-struct S getS();
-
-
-void testAssignment() {
-  struct S s = getS();
-
-  if (s.field != 42) return;
-  clang_analyzer_eval(s.field == 42); // expected-warning{{TRUE}}
-
-  s.field = 0;
-  clang_analyzer_eval(s.field == 0); // expected-warning{{TRUE}}
-
-#if __cplusplus
-  clang_analyzer_eval(s.getThis() == &s); // expected-warning{{TRUE}}
-#endif
-}
-
-
-void testImmediateUse() {
-  int x = getS().field;
-
-  if (x != 42) return;
-  clang_analyzer_eval(x == 42); // expected-warning{{TRUE}}
-
-#if __cplusplus
-  clang_analyzer_eval((void *)getS().getThis() == (void *)&x); // expected-warning{{FALSE}}
-#endif
-}
-
-int getConstrainedField(struct S s) {
-  if (s.field != 42) return 42;
-  return s.field;
-}
-
-int getAssignedField(struct S s) {
-  s.field = 42;
-  return s.field;
-}
-
-void testArgument() {
-  clang_analyzer_eval(getConstrainedField(getS()) == 42); // expected-warning{{TRUE}}
-  clang_analyzer_eval(getAssignedField(getS()) == 42); // expected-warning{{TRUE}}
-}
-
-
-//--------------------
-// C++-only tests
-//--------------------
-
-#if __cplusplus
-void testReferenceAssignment() {
-  const S &s = getS();
-
-  if (s.field != 42) return;
-  clang_analyzer_eval(s.field == 42); // expected-warning{{TRUE}}
-
-  clang_analyzer_eval(s.getThis() == &s); // expected-warning{{TRUE}}
-}
-
-
-int getConstrainedFieldRef(const S &s) {
-  if (s.field != 42) return 42;
-  return s.field;
-}
-
-bool checkThis(const S &s) {
-  return s.getThis() == &s;
-}
-
-void testReferenceArgument() {
-  clang_analyzer_eval(getConstrainedFieldRef(getS()) == 42); // expected-warning{{TRUE}}
-  clang_analyzer_eval(checkThis(getS())); // expected-warning{{TRUE}}
-}
-#endif
diff --git a/test/Analysis/reference.cpp b/test/Analysis/reference.cpp
index ce0ee8e..4a2cbb8 100644
--- a/test/Analysis/reference.cpp
+++ b/test/Analysis/reference.cpp
@@ -116,11 +116,8 @@
 
   struct S { int &x; };
 
-  extern S getS();
-  clang_analyzer_eval(&getS().x != 0); // expected-warning{{TRUE}}
-
-  extern S *getSP();
-  clang_analyzer_eval(&getSP()->x != 0); // expected-warning{{TRUE}}
+  extern S *getS();
+  clang_analyzer_eval(&getS()->x != 0); // expected-warning{{TRUE}}
 }
 
 
@@ -153,3 +150,10 @@
     return *x; // should warn here!
   }
 }
+
+void testReferenceFieldAddress() {
+  struct S { int &x; };
+
+  extern S getS();
+  clang_analyzer_eval(&getS().x != 0); // expected-warning{{UNKNOWN}}
+}