r346065 - Revert r345562: "PR23833, DR2140: an lvalue-to-rvalue conversion on a glvalue of type"
Richard Smith via cfe-commits
cfe-commits at lists.llvm.org
Fri Nov 2 19:23:33 PDT 2018
Author: rsmith
Date: Fri Nov 2 19:23:33 2018
New Revision: 346065
URL: http://llvm.org/viewvc/llvm-project?rev=346065&view=rev
Log:
Revert r345562: "PR23833, DR2140: an lvalue-to-rvalue conversion on a glvalue of type"
This exposes a (known) CodeGen bug: it can't cope with emitting lvalue
expressions that denote non-odr-used but usable-in-constant-expression
variables. See PR39528 for a testcase.
Reverted for now until that issue can be fixed.
Modified:
cfe/trunk/lib/AST/Expr.cpp
cfe/trunk/lib/CodeGen/CGExprAgg.cpp
cfe/trunk/lib/CodeGen/CGExprScalar.cpp
cfe/trunk/lib/Sema/SemaExpr.cpp
cfe/trunk/lib/Sema/SemaInit.cpp
cfe/trunk/lib/StaticAnalyzer/Core/ExprEngineC.cpp
cfe/trunk/test/Analysis/nullptr.cpp
cfe/trunk/test/CXX/drs/dr21xx.cpp
cfe/trunk/test/CodeGenCXX/nullptr.cpp
cfe/trunk/www/cxx_dr_status.html
Modified: cfe/trunk/lib/AST/Expr.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/Expr.cpp?rev=346065&r1=346064&r2=346065&view=diff
==============================================================================
--- cfe/trunk/lib/AST/Expr.cpp (original)
+++ cfe/trunk/lib/AST/Expr.cpp Fri Nov 2 19:23:33 2018
@@ -1816,11 +1816,6 @@ ImplicitCastExpr *ImplicitCastExpr::Crea
void *Buffer =
C.Allocate(totalSizeToAlloc<CastExpr::BasePathSizeTy, CXXBaseSpecifier *>(
PathSize ? 1 : 0, PathSize));
- // Per C++ [conv.lval]p3, lvalue-to-rvalue conversions on class and
- // std::nullptr_t have special semantics not captured by CK_LValueToRValue.
- assert((Kind != CK_LValueToRValue ||
- !(T->isNullPtrType() || T->getAsCXXRecordDecl())) &&
- "invalid type for lvalue-to-rvalue conversion");
ImplicitCastExpr *E =
new (Buffer) ImplicitCastExpr(T, Kind, Operand, PathSize, VK);
if (PathSize)
Modified: cfe/trunk/lib/CodeGen/CGExprAgg.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGExprAgg.cpp?rev=346065&r1=346064&r2=346065&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGExprAgg.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGExprAgg.cpp Fri Nov 2 19:23:33 2018
@@ -1300,8 +1300,7 @@ static bool isSimpleZero(const Expr *E,
// (int*)0 - Null pointer expressions.
if (const CastExpr *ICE = dyn_cast<CastExpr>(E))
return ICE->getCastKind() == CK_NullToPointer &&
- CGF.getTypes().isPointerZeroInitializable(E->getType()) &&
- !E->HasSideEffects(CGF.getContext());
+ CGF.getTypes().isPointerZeroInitializable(E->getType());
// '\0'
if (const CharacterLiteral *CL = dyn_cast<CharacterLiteral>(E))
return CL->getValue() == 0;
Modified: cfe/trunk/lib/CodeGen/CGExprScalar.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGExprScalar.cpp?rev=346065&r1=346064&r2=346065&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGExprScalar.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGExprScalar.cpp Fri Nov 2 19:23:33 2018
@@ -2072,14 +2072,14 @@ Value *ScalarExprEmitter::VisitCastExpr(
case CK_NullToPointer:
if (MustVisitNullValue(E))
- CGF.EmitIgnoredExpr(E);
+ (void) Visit(E);
return CGF.CGM.getNullPointer(cast<llvm::PointerType>(ConvertType(DestTy)),
DestTy);
case CK_NullToMemberPointer: {
if (MustVisitNullValue(E))
- CGF.EmitIgnoredExpr(E);
+ (void) Visit(E);
const MemberPointerType *MPT = CE->getType()->getAs<MemberPointerType>();
return CGF.CGM.getCXXABI().EmitNullMemberPointer(MPT);
Modified: cfe/trunk/lib/Sema/SemaExpr.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExpr.cpp?rev=346065&r1=346064&r2=346065&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaExpr.cpp (original)
+++ cfe/trunk/lib/Sema/SemaExpr.cpp Fri Nov 2 19:23:33 2018
@@ -623,11 +623,8 @@ ExprResult Sema::DefaultLvalueConversion
if (E->getType().getObjCLifetime() == Qualifiers::OCL_Weak)
Cleanup.setExprNeedsCleanups(true);
- // C++ [conv.lval]p3:
- // If T is cv std::nullptr_t, the result is a null pointer constant.
- CastKind CK = T->isNullPtrType() ? CK_NullToPointer : CK_LValueToRValue;
- ExprResult Res =
- ImplicitCastExpr::Create(Context, T, CK, E, nullptr, VK_RValue);
+ ExprResult Res = ImplicitCastExpr::Create(Context, T, CK_LValueToRValue, E,
+ nullptr, VK_RValue);
// C11 6.3.2.1p2:
// ... if the lvalue has atomic type, the value has the non-atomic version
Modified: cfe/trunk/lib/Sema/SemaInit.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaInit.cpp?rev=346065&r1=346064&r2=346065&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaInit.cpp (original)
+++ cfe/trunk/lib/Sema/SemaInit.cpp Fri Nov 2 19:23:33 2018
@@ -7644,13 +7644,9 @@ InitializationSequence::Perform(Sema &S,
case SK_LValueToRValue: {
assert(CurInit.get()->isGLValue() && "cannot load from a prvalue");
- // C++ [conv.lval]p3:
- // If T is cv std::nullptr_t, the result is a null pointer constant.
- CastKind CK =
- Step->Type->isNullPtrType() ? CK_NullToPointer : CK_LValueToRValue;
- CurInit =
- ImplicitCastExpr::Create(S.Context, Step->Type, CK, CurInit.get(),
- /*BasePath=*/nullptr, VK_RValue);
+ CurInit = ImplicitCastExpr::Create(S.Context, Step->Type,
+ CK_LValueToRValue, CurInit.get(),
+ /*BasePath=*/nullptr, VK_RValue);
break;
}
Modified: cfe/trunk/lib/StaticAnalyzer/Core/ExprEngineC.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/StaticAnalyzer/Core/ExprEngineC.cpp?rev=346065&r1=346064&r2=346065&view=diff
==============================================================================
--- cfe/trunk/lib/StaticAnalyzer/Core/ExprEngineC.cpp (original)
+++ cfe/trunk/lib/StaticAnalyzer/Core/ExprEngineC.cpp Fri Nov 2 19:23:33 2018
@@ -379,6 +379,7 @@ void ExprEngine::VisitCast(const CastExp
case CK_BitCast:
case CK_AddressSpaceConversion:
case CK_BooleanToSignedIntegral:
+ case CK_NullToPointer:
case CK_IntegralToPointer:
case CK_PointerToIntegral: {
SVal V = state->getSVal(Ex, LCtx);
@@ -501,12 +502,6 @@ void ExprEngine::VisitCast(const CastExp
Bldr.generateNode(CastE, Pred, state);
continue;
}
- case CK_NullToPointer: {
- SVal V = svalBuilder.makeNull();
- state = state->BindExpr(CastE, LCtx, V);
- Bldr.generateNode(CastE, Pred, state);
- continue;
- }
case CK_NullToMemberPointer: {
SVal V = svalBuilder.getMemberPointer(nullptr);
state = state->BindExpr(CastE, LCtx, V);
Modified: cfe/trunk/test/Analysis/nullptr.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Analysis/nullptr.cpp?rev=346065&r1=346064&r2=346065&view=diff
==============================================================================
--- cfe/trunk/test/Analysis/nullptr.cpp (original)
+++ cfe/trunk/test/Analysis/nullptr.cpp Fri Nov 2 19:23:33 2018
@@ -128,10 +128,18 @@ void shouldNotCrash() {
decltype(nullptr) p; // expected-note{{'p' declared without an initial value}}
if (getSymbol()) // expected-note {{Assuming the condition is false}}
// expected-note at -1{{Taking false branch}}
+ // expected-note at -2{{Assuming the condition is false}}
+ // expected-note at -3{{Taking false branch}}
+ // expected-note at -4{{Assuming the condition is true}}
+ // expected-note at -5{{Taking true branch}}
+ invokeF(p); // expected-warning{{1st function call argument is an uninitialized value}}
+ // expected-note at -1{{1st function call argument is an uninitialized value}}
+ if (getSymbol()) // expected-note {{Assuming the condition is false}}
+ // expected-note at -1{{Taking false branch}}
// expected-note at -2{{Assuming the condition is true}}
// expected-note at -3{{Taking true branch}}
- invokeF(p); // expected-note {{Calling 'invokeF'}}
- // expected-note at -1{{Passing null pointer value via 1st parameter 'x'}}
+ invokeF(nullptr); // expected-note {{Calling 'invokeF'}}
+ // expected-note at -1{{Passing null pointer value via 1st parameter 'x'}}
if (getSymbol()) { // expected-note {{Assuming the condition is true}}
// expected-note at -1{{Taking true branch}}
X *xx = Type().x; // expected-note {{Null pointer value stored to field 'x'}}
Modified: cfe/trunk/test/CXX/drs/dr21xx.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CXX/drs/dr21xx.cpp?rev=346065&r1=346064&r2=346065&view=diff
==============================================================================
--- cfe/trunk/test/CXX/drs/dr21xx.cpp (original)
+++ cfe/trunk/test/CXX/drs/dr21xx.cpp Fri Nov 2 19:23:33 2018
@@ -19,16 +19,6 @@ namespace dr2120 { // dr2120: 7
static_assert(!__is_standard_layout(E), "");
}
-namespace dr2140 { // dr2140: 8
-#if __cplusplus >= 201103L
- union U { int a; decltype(nullptr) b; };
- constexpr int *test(U u) {
- return u.b;
- }
- static_assert(!test({123}), "u.b should be valid even when b is inactive");
-#endif
-}
-
namespace dr2180 { // dr2180: yes
class A {
A &operator=(const A &); // expected-note 0-2{{here}}
Modified: cfe/trunk/test/CodeGenCXX/nullptr.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/nullptr.cpp?rev=346065&r1=346064&r2=346065&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenCXX/nullptr.cpp (original)
+++ cfe/trunk/test/CodeGenCXX/nullptr.cpp Fri Nov 2 19:23:33 2018
@@ -22,44 +22,3 @@ void g() {
const std::type_info& f2() {
return typeid(nullptr_t);
}
-
-union U {
- int n;
- nullptr_t b;
-};
-// CHECK-LABEL: define {{.*}}pr23833_a
-// CHECK: store
-// CHECK: load
-// CHECK-NOT: load
-// CHECK: ret i1 false
-bool pr23833_a(U &u) { return u.b; }
-
-// CHECK-LABEL: define {{.*}}pr23833_b
-// CHECK: store
-// CHECK: load
-// CHECK-NOT: load
-// CHECK: ret i8* null
-nullptr_t pr23833_b(nullptr_t &n) { return n; }
-
-struct X1 { operator int*(); };
-struct X2 { operator const nullptr_t&(); };
-
-// CHECK-LABEL: define {{.*}}pr23833_c
-// CHECK: call {{.*}}X1
-// CHECK: call {{.*}}X2
-// CHECK-NOT: load
-// CHECK: ret i32
-int pr23833_c() {
- return X1() != X2();
-}
-
-// CHECK-LABEL: define {{.*}}pr23833_d
-// CHECK: call {{.*}}X2
-// CHECK-NOT: load
-// CHECK: store
-// CHECK: load
-// CHECK: ret i32*
-int *pr23833_d() {
- int *p = X2();
- return p;
-}
Modified: cfe/trunk/www/cxx_dr_status.html
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/www/cxx_dr_status.html?rev=346065&r1=346064&r2=346065&view=diff
==============================================================================
--- cfe/trunk/www/cxx_dr_status.html (original)
+++ cfe/trunk/www/cxx_dr_status.html Fri Nov 2 19:23:33 2018
@@ -12655,7 +12655,7 @@ and <I>POD class</I></td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#2140">2140</a></td>
<td>CD4</td>
<td>Lvalue-to-rvalue conversion of <TT>std::nullptr_t</TT></td>
- <td class="svn" align="center">SVN</td>
+ <td class="none" align="center">Unknown</td>
</tr>
<tr id="2141">
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#2141">2141</a></td>
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