r229213 - DR1748: the reserved placement allocation functions have undefined behavior if
Richard Smith
richard-llvm at metafoo.co.uk
Fri Feb 13 17:52:21 PST 2015
Author: rsmith
Date: Fri Feb 13 19:52:20 2015
New Revision: 229213
URL: http://llvm.org/viewvc/llvm-project?rev=229213&view=rev
Log:
DR1748: the reserved placement allocation functions have undefined behavior if
they're given a null pointer as an argument, so we do not need to emit null
checks on their results.
Modified:
cfe/trunk/include/clang/AST/ExprCXX.h
cfe/trunk/lib/AST/ExprCXX.cpp
cfe/trunk/lib/CodeGen/CGExprCXX.cpp
cfe/trunk/test/CodeGenCXX/debug-info-line.cpp
cfe/trunk/test/CodeGenCXX/new.cpp
Modified: cfe/trunk/include/clang/AST/ExprCXX.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/ExprCXX.h?rev=229213&r1=229212&r2=229213&view=diff
==============================================================================
--- cfe/trunk/include/clang/AST/ExprCXX.h (original)
+++ cfe/trunk/include/clang/AST/ExprCXX.h Fri Feb 13 19:52:20 2015
@@ -1692,6 +1692,10 @@ public:
/// not be done, the deallocation function shall not be called,
/// and the value of the new-expression shall be null.
///
+ /// C++ DR1748:
+ /// If the allocation function is a reserved placement allocation
+ /// function that returns null, the behavior is undefined.
+ ///
/// An allocation function is not allowed to return null unless it
/// has a non-throwing exception-specification. The '03 rule is
/// identical except that the definition of a non-throwing
Modified: cfe/trunk/lib/AST/ExprCXX.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ExprCXX.cpp?rev=229213&r1=229212&r2=229213&view=diff
==============================================================================
--- cfe/trunk/lib/AST/ExprCXX.cpp (original)
+++ cfe/trunk/lib/AST/ExprCXX.cpp Fri Feb 13 19:52:20 2015
@@ -208,8 +208,9 @@ void CXXNewExpr::AllocateArgsArray(const
}
bool CXXNewExpr::shouldNullCheckAllocation(const ASTContext &Ctx) const {
- return getOperatorNew()->getType()->
- castAs<FunctionProtoType>()->isNothrow(Ctx);
+ return getOperatorNew()->getType()->castAs<FunctionProtoType>()->isNothrow(
+ Ctx) &&
+ !getOperatorNew()->isReservedGlobalPlacementOperator();
}
// CXXDeleteExpr
Modified: cfe/trunk/lib/CodeGen/CGExprCXX.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGExprCXX.cpp?rev=229213&r1=229212&r2=229213&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGExprCXX.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGExprCXX.cpp Fri Feb 13 19:52:20 2015
@@ -1279,10 +1279,9 @@ llvm::Value *CodeGenFunction::EmitCXXNew
// Emit a null check on the allocation result if the allocation
// function is allowed to return null (because it has a non-throwing
- // exception spec; for this part, we inline
- // CXXNewExpr::shouldNullCheckAllocation()) and we have an
+ // exception spec or is the reserved placement new) and we have an
// interesting initializer.
- bool nullCheck = allocatorType->isNothrow(getContext()) &&
+ bool nullCheck = E->shouldNullCheckAllocation(getContext()) &&
(!allocType.isPODType(getContext()) || E->hasInitializer());
llvm::BasicBlock *nullCheckBB = nullptr;
Modified: cfe/trunk/test/CodeGenCXX/debug-info-line.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/debug-info-line.cpp?rev=229213&r1=229212&r2=229213&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenCXX/debug-info-line.cpp (original)
+++ cfe/trunk/test/CodeGenCXX/debug-info-line.cpp Fri Feb 13 19:52:20 2015
@@ -113,7 +113,7 @@ inline void *operator new(decltype(sizeo
// CHECK-LABEL: define
void f10() {
void *void_src();
- ( // CHECK: icmp {{.*}} !dbg [[DBG_F10_ICMP:.*]]
+ (
// CHECK: store {{.*}} !dbg [[DBG_F10_STORE:!.*]]
#line 1100
new (void_src()) int(src()));
@@ -305,7 +305,6 @@ void f24() {
// CHECK: [[DBG_F7]] = !MDLocation(line: 800,
// CHECK: [[DBG_F8]] = !MDLocation(line: 900,
// CHECK: [[DBG_F9]] = !MDLocation(line: 1000,
-// CHECK: [[DBG_F10_ICMP]] = !MDLocation(line: 1100,
// CHECK: [[DBG_F10_STORE]] = !MDLocation(line: 1100,
// CHECK: [[DBG_GLBL_CTOR_B]] = !MDLocation(line: 1200,
// CHECK: [[DBG_GLBL_DTOR_B]] = !MDLocation(line: 1200,
Modified: cfe/trunk/test/CodeGenCXX/new.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/new.cpp?rev=229213&r1=229212&r2=229213&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenCXX/new.cpp (original)
+++ cfe/trunk/test/CodeGenCXX/new.cpp Fri Feb 13 19:52:20 2015
@@ -36,6 +36,10 @@ void *operator new[](size_t, const std::
void operator delete(void *, const std::nothrow_t &) throw();
void operator delete[](void *, const std::nothrow_t &) throw();
+// Declare some other placemenet operators.
+void *operator new(size_t, void*, bool) throw();
+void *operator new[](size_t, void*, bool) throw();
+
void t2(int* a) {
int* b = new (a) int;
}
@@ -191,20 +195,31 @@ void f() {
namespace test15 {
struct A { A(); ~A(); };
- // CHECK-LABEL: define void @_ZN6test155test0EPv(
+ // CHECK-LABEL: define void @_ZN6test156test0aEPv(
// CHECK: [[P:%.*]] = load i8*
- // CHECK-NEXT: icmp eq i8* [[P]], null
- // CHECK-NEXT: br i1
+ // CHECK-NOT: icmp eq i8* [[P]], null
+ // CHECK-NOT: br i1
// CHECK: [[T0:%.*]] = bitcast i8* [[P]] to [[A:%.*]]*
// CHECK-NEXT: call void @_ZN6test151AC1Ev([[A]]* [[T0]])
- void test0(void *p) {
+ void test0a(void *p) {
new (p) A();
}
- // CHECK-LABEL: define void @_ZN6test155test1EPv(
- // CHECK: [[P:%.*]] = load i8**
+ // CHECK-LABEL: define void @_ZN6test156test0bEPv(
+ // CHECK: [[P0:%.*]] = load i8*
+ // CHECK: [[P:%.*]] = call i8* @_ZnwmPvb(i64 1, i8* [[P0]]
// CHECK-NEXT: icmp eq i8* [[P]], null
// CHECK-NEXT: br i1
+ // CHECK: [[T0:%.*]] = bitcast i8* [[P]] to [[A:%.*]]*
+ // CHECK-NEXT: call void @_ZN6test151AC1Ev([[A]]* [[T0]])
+ void test0b(void *p) {
+ new (p, true) A();
+ }
+
+ // CHECK-LABEL: define void @_ZN6test156test1aEPv(
+ // CHECK: [[P:%.*]] = load i8**
+ // CHECK-NOT: icmp eq i8* [[P]], null
+ // CHECK-NOT: br i1
// CHECK: [[BEGIN:%.*]] = bitcast i8* [[P]] to [[A:%.*]]*
// CHECK-NEXT: [[END:%.*]] = getelementptr inbounds [[A]]* [[BEGIN]], i64 5
// CHECK-NEXT: br label
@@ -213,10 +228,28 @@ namespace test15 {
// CHECK-NEXT: [[NEXT]] = getelementptr inbounds [[A]]* [[CUR]], i64 1
// CHECK-NEXT: [[DONE:%.*]] = icmp eq [[A]]* [[NEXT]], [[END]]
// CHECK-NEXT: br i1 [[DONE]]
- void test1(void *p) {
+ void test1a(void *p) {
new (p) A[5];
}
+ // CHECK-LABEL: define void @_ZN6test156test1bEPv(
+ // CHECK: [[P0:%.*]] = load i8**
+ // CHECK: [[P:%.*]] = call i8* @_ZnamPvb(i64 13, i8* [[P0]]
+ // CHECK-NEXT: icmp eq i8* [[P]], null
+ // CHECK-NEXT: br i1
+ // CHECK: [[AFTER_COOKIE:%.*]] = getelementptr inbounds i8* [[P]], i64 8
+ // CHECK: [[BEGIN:%.*]] = bitcast i8* [[AFTER_COOKIE]] to [[A:%.*]]*
+ // CHECK-NEXT: [[END:%.*]] = getelementptr inbounds [[A]]* [[BEGIN]], i64 5
+ // CHECK-NEXT: br label
+ // CHECK: [[CUR:%.*]] = phi [[A]]* [ [[BEGIN]], {{%.*}} ], [ [[NEXT:%.*]], {{%.*}} ]
+ // CHECK-NEXT: call void @_ZN6test151AC1Ev([[A]]* [[CUR]])
+ // CHECK-NEXT: [[NEXT]] = getelementptr inbounds [[A]]* [[CUR]], i64 1
+ // CHECK-NEXT: [[DONE:%.*]] = icmp eq [[A]]* [[NEXT]], [[END]]
+ // CHECK-NEXT: br i1 [[DONE]]
+ void test1b(void *p) {
+ new (p, true) A[5];
+ }
+
// TODO: it's okay if all these size calculations get dropped.
// FIXME: maybe we should try to throw on overflow?
// CHECK-LABEL: define void @_ZN6test155test2EPvi(
@@ -225,8 +258,6 @@ namespace test15 {
// CHECK-NEXT: [[T1:%.*]] = icmp slt i64 [[T0]], 0
// CHECK-NEXT: [[T2:%.*]] = select i1 [[T1]], i64 -1, i64 [[T0]]
// CHECK-NEXT: [[P:%.*]] = load i8*
- // CHECK-NEXT: icmp eq i8* [[P]], null
- // CHECK-NEXT: br i1
// CHECK: [[BEGIN:%.*]] = bitcast i8* [[P]] to [[A:%.*]]*
// CHECK-NEXT: [[ISEMPTY:%.*]] = icmp eq i64 [[T0]], 0
// CHECK-NEXT: br i1 [[ISEMPTY]],
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