[PATCH] D24812: Lit C++11 Compatibility Patch #11
Charles Li via cfe-commits
cfe-commits at lists.llvm.org
Wed Sep 21 12:00:03 PDT 2016
tigerleapgorge created this revision.
tigerleapgorge added a reviewer: rsmith.
tigerleapgorge added a subscriber: cfe-commits.
Herald added a subscriber: aemerson.
Hi Everyone,
Here is the 11th Lit C++11 compatibility patch.
This will most likely be my final Lit patch.
I have updated 16 tests this time.
Here are the explanations for each test.
CodeGenCXX/exceptions.cpp
Implicit destructors are noexcept (nothrow) in C++11.
The LLVM IR invocation for these destructors changed from “invoke” to “call”.
This is related to C++11’s standard 15.4\14 and 15.4\15 in [except.spec]
In C++11, Clang marks implicit destructors as “nothrow” in the AST and “nounwind” in the LLVM IR.
[except.spec] 15.4\14
An implicitly declared special member function shall have an exception-specification.
If f is an implicitly declared default constructor, copy constructor, move constructor,
destructor, copy assignment operator, or move assignment operator,
its implicit exception-specification specifies the type-id T if and only if T is allowed
by the exception-specification of a function directly invoked by f’s implicit definition;
f shall allow all exceptions if any function it directly invokes allows all exceptions,
and f shall allow no exceptions if every function it directly invokes allows no exceptions.
[except.spec] 15.4\15
A deallocation function (3.7.4.2) with no explicit exception-specification
is treated as if it were specified with noexcept(true).
IR changes are as follows:
test1::B::~B() is nothrow in C++11. IR for its invocation changed from invoke to call.
C++98: invoke void @_ZN5test11BD1Ev(%"struct.test1::B"* %temp.lvalue)
C++98: to label %invoke.cont4 unwind label %terminate.lpad
C++11: call void @_ZN5test11BD1Ev(%"struct.test1::B"* %temp.lvalue) #8
The landing pad and its associated attribute no longer exists in C++11.
C++98: ; Function Attrs: noinline noreturn nounwind
C++98: define linkonce_odr hidden void @__clang_call_terminate(i8*) #4 comdat {
C++98: %2 = call i8* @__cxa_begin_catch(i8* %0) #8
C++98: call void @_ZSt9terminatev() #12
C++98: unreachable
C++98: }
C++98: attributes #4 = { noinline noreturn nounwind }
C++11: <does not exist>
test2::A::operator delete(void*, unsigned long) is nothrow in C++11.
test3::A::operator delete(void*, void*, double) is nothrow in C++11.
test5::T::~T() is nothrow in C++11.
test7::A::~A() is nothrow in C++11.
test10::C::~C() is nothrow in C++11.
test11::A::~A() is nothrow in C++11
CodeGenCXX/lpad-linetable.cpp
The purpose of this test is to verify landingpad line numbers when catching
any exceptions thrown by the destructors for “longs” and “shorts” as they go out of scope.
However, in C++11, “longs” and “short”’s destructors are noexcept (nothrow).
~std::_Vector_base<long, std::allocator<long> >() noexcept
~std::_Vector_base<short, std::allocator<short> >() noexcept
Because these destructors no longer throw any exceptions in C++11, there is no need to generate the landingpads.
And since the purpose of this test is to verify for landingpad line table, I have restricted this test to C++98.
CodeGenCXX/mangle-unnamed.cpp
Test section f6() verifies the mangled name of the variable b that is inside
the static anonymous union along with an anonymous union of a unnamed bit field.
Running this test in C++11 results in the following error.
error: call to implicitly-deleted default constructor of '(anonymous union at t.cpp:2:10)'
note: default constructor of '' is implicitly deleted because field '' has a deleted default constructor
note: default constructor of '' is implicitly deleted because all data members are const-qualified
This is most likely due to interaction between three parts of the C++11 standard:
1. Unnamed bit-field cannot be initialized.
C++ Standard section 9.6.2 [class.bit]
A declaration for a bit-field that omits the identifier declares an unnamed bit-field.
Unnamed bit-fields are not members and cannot be initialized.
2. Introduction of keyword “delete”.
3. Change in rules regarding Unions.
http://www.stroustrup.com/C++11FAQ.html#unions
If a union has a member with a user-defined constructor, copy, or destructor
then that special function is deleted;
that is, it cannot be used for an object of the union type. This is new.
For f6(), Since the unnamed bitfield “int : 1;” can not be initialized,
its constructor is considered “deleted”, therefore it cannot be used inside a union.
Hence f6() would be an invalid test for C++11.
Since this test verifies for name managling, I have restricted f6() to C++98.
CodeGenCXX/arm.cpp
test3::A::~A() is noexcept (nothrow) in C++11.
LLVM IR invocation for this destructor has changed from “invoke” to “call”.
CodeGenCXX/eh-aggregate-copy-destroy.cpp
ImplicitCopy::~ImplicitCopy()is noexcept (nothrow) in C++11.
LLVM IR invocation for this destructor has changed from “invoke” to “call”.
CodeGenCXX/debug-info-class.cpp
B::~B()is noexcept (nothrow) in C++11.
LLVM IR invocation for this destructor has changed from “invoke” to “call”.
CodeGenCXX/goto.cpp
test0::A::~A() is noexcept (nothrow) in C++11.
IR invocation for this destructor changed from invoke to call.
CodeGenCXX/linetable-cleanup.cpp
C::~C() has a nounwind attribute in C++11.
Interestingly enough, IR invocation is "call" in both C++98 and C++11,
The only difference is the extra attribute “#2”.
IR changes are as follows:
C++98: call void @_ZN1CD1Ev(%class.C* %c), !dbg !21
C++11: call void @_ZN1CD1Ev(%class.C* %c) #2, !dbg !21
attributes #2 = { nounwind }
Relaxed the CHECK pattern matching to accommodate for possible existence of “ #[0-9]”.
CodeGenCXX/static-init.cpp
Inside test4,
The LLVM IR for useStaticLocal() has been greatly simplified in C++11.
This is likely due to C++11 Standard section 6.7.4 [stmt.dcl]
The zero-initialization (8.5) of all block-scope variables with static storage duration (3.7.1)
or thread storage duration (3.7.2) is performed before any other initialization takes place.
Since Struct HasVTable only has a virtual method f that is declared but not defined,
Clang likely assumed that no initialization is needed inside routine useStaticLocal().
Therefore Clang in C++11 no longer generates the default contructors for HasVTable nor
the singleton pattern to guard against reinitialization of HasVTable.
Relevant IR changes are shown below.
C++98 IR:
@_ZZN5test414useStaticLocalEvE3obj = linkonce_odr global %"struct.test4::HasVTable" zeroinitializer, comdat, align 8
@_ZGVZN5test414useStaticLocalEvE3obj = linkonce_odr global i64 0, comdat, align 8
; Function Attrs: inlinehint nounwind
define linkonce_odr dereferenceable(8) %"struct.test4::HasVTable"* @_ZN5test414useStaticLocalEv() #4 comdat {
entry:
%0 = load atomic i8, i8* bitcast (i64* @_ZGVZN5test414useStaticLocalEvE3obj to i8*) acquire, align 8
%guard.uninitialized = icmp eq i8 %0, 0
br i1 %guard.uninitialized, label %init.check, label %init.end
init.check: ; preds = %entry
%1 = call i32 @__cxa_guard_acquire(i64* @_ZGVZN5test414useStaticLocalEvE3obj) #1
%tobool = icmp ne i32 %1, 0
br i1 %tobool, label %init, label %init.end
init: ; preds = %init.check
call void @_ZN5test49HasVTableC1Ev(%"struct.test4::HasVTable"* @_ZZN5test414useStaticLocalEvE3obj) #1
call void @__cxa_guard_release(i64* @_ZGVZN5test414useStaticLocalEvE3obj) #1
br label %init.end
init.end: ; preds = %init, %init.check, %entry
ret %"struct.test4::HasVTable"* @_ZZN5test414useStaticLocalEvE3obj
}
; Function Attrs: inlinehint nounwind
define linkonce_odr void @_ZN5test49HasVTableC1Ev(%"struct.test4::HasVTable"* %this) unnamed_addr #4 comdat align 2 {
entry:
%this.addr = alloca %"struct.test4::HasVTable"*, align 8
store %"struct.test4::HasVTable"* %this, %"struct.test4::HasVTable"** %this.addr, align 8
%this1 = load %"struct.test4::HasVTable"*, %"struct.test4::HasVTable"** %this.addr, align 8
call void @_ZN5test49HasVTableC2Ev(%"struct.test4::HasVTable"* %this1) #1
ret void
}
; Function Attrs: inlinehint nounwind
define linkonce_odr void @_ZN5test49HasVTableC2Ev(%"struct.test4::HasVTable"* %this) unnamed_addr #4 comdat align 2 {
entry:
%this.addr = alloca %"struct.test4::HasVTable"*, align 8
store %"struct.test4::HasVTable"* %this, %"struct.test4::HasVTable"** %this.addr, align 8
%this1 = load %"struct.test4::HasVTable"*, %"struct.test4::HasVTable"** %this.addr, align 8
%0 = bitcast %"struct.test4::HasVTable"* %this1 to i32 (...)***
store i32 (...)** bitcast (i8** getelementptr inbounds ([3 x i8*], [3 x i8*]* @_ZTVN5test49HasVTableE, i32 0, i32 2)
to i32 (...)**), i32 (...)*** %0, align 8
ret void
}
C++11 IR:
@_ZZN5test414useStaticLocalEvE3obj = linkonce_odr global { i8** } { i8** getelementptr inbounds ([3 x i8*],
[3 x i8*]* @_ZTVN5test49HasVTableE, i32 0, i32 2) }, comdat, align 8
; Function Attrs: inlinehint nounwind
define linkonce_odr dereferenceable(8) %"struct.test4::HasVTable"* @_ZN5test414useStaticLocalEv() #5 comdat {
entry:
ret %"struct.test4::HasVTable"* bitcast ({ i8** }* @_ZZN5test414useStaticLocalEvE3obj to %"struct.test4::HasVTable"*)
}
CodeGenCXX/value-init.cpp
Section Test2:
For the empty list initialization of an array of struct Test2, Clang has inlined the constructor call for t().
struct Test2 {
Test t;
};
Test2 empty2[3] = {};
In C++98, Clang will call Test2()
In C++11, Clang will load the member t and call Test() on it.
Here are the IR changes.
C++98: call void @_ZN6PR98015Test2C1Ev(%"struct.PR9801::Test2"* %arrayinit.cur12)
C++11: %t = getelementptr inbounds %"struct.PR9801::Test2", %"struct.PR9801::Test2"* %arrayinit.cur12, i32 0, i32 0
C++11: call void @_ZN6PR98014TestC1Ev(%"struct.PR9801::Test"* %t)
For the sake of simplicity, I have restricted the 2 CHECK lines to C++98.
Section test6:
The index arguments type has changed from i32 to i64.
C++98: %array.begin = getelementptr inbounds [20 x %struct.A], [20 x %struct.A]* %arrayinit.cur6, i32 0, i32 0
C++11: %arrayinit.begin7 = getelementptr inbounds [20 x %struct.A], [20 x %struct.A]* %arrayinit.cur6, i64 0, i64 0
According to the LLVM Language Reference Manual, this is valid.
http://llvm.org/docs/LangRef.html#id213
When indexing into an array, pointer or vector, integers of any width are allowed,
and they are not required to be constant. These integers are treated as signed values where relevant.
Relaxed pattern matching to accommodate allow for i[0-9]+
CodeGenCXX/volatile-1.cpp
In C++11, volatile accesses in discarded-value expressions generate loads in the LLVM IR.
Add the “load volatile” for the following cases.
i;
(void)ci;
(void)i;
(void)(i,(i=i));
i=i,k;
(i=j,k);
(i,j);
ci;
(i,j)=k;
CodeGenCXX/volatile.cpp
This test checks for the IR of volatile pointer dereferences.
In C++11, *x; resulted in an additional “load volatile”.
This is because *x; is an indirection of the volatile qualified x inside a discarded-value expression.
http://open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#1054
And according to the standard defect fix 1054, this is now an use of x.
http://stackoverflow.com/questions/20242868/correct-behaviour-of-trivial-statements-involving-expressions-with-volatile-vari
Expect the following extra line of IR in C++11.
Existing: %0 = load i32*, i32** @_ZN5test11xE, align 8
C++11: %1 = load volatile i32, i32* %0, align 4
Existing: ret void
Index/comment-cplus-decls.cpp
In C++11, Test’s destructor has a noexcept attribute.
C++98: <Declaration>~Test()</Declaration>
C++11: <Declaration>~Test() noexcept</Declaration>
OpenMP/atomic_codegen.cpp
St::~St() is noexcept (nothrow) in C++11.
IR for the invocation of this destructor has changed from “invoke” to “call”.
OpenMP/threadprivate_codegen.cpp
S1::~S1() is noexcept (nothrow) in C++11.
IR for the invocation of this destructor has changed from “invoke” to “call”.
CHECK-DEBUG-DAG (line 147 - 166) verifies for source code position. No new run line is added to keep line numbers the same.
PCH/macro-undef.cpp
This test uses uninitialized variable diagnostics to verify macro undef behavior across PCH export and import.
This test is compiled 3 times.
1st time, the function template definitions for f() and g() are exported to a PCH file.
2nd time, the PCH is imported to compile the main() function. Inside main, f() and g() are instantiated. The diagnostics is checked.
3nd time, the PCH is imported to compile the main() function. Inside main, f() and g() are instantiated. The fix-it line of the diagnostics is checked.
The fix-it line differs depending on if the macro NULL is defined or undefined.
However, because C++11 introduced ‘nullptr’, the fix-it message no longer differs.
In C++98, when NULL is defined to 0, the fix it message will use NULL (at line 11)
When NULL is undefined, the fix it message will use 0 (at line 17).
In C++11, the fix it message will use ‘nullptr’ whether or not NULL is defined or undefined.
C++98: note: initialize the variable 'p' to silence this warning
void *p; // @11
^
= NULL
note: initialize the variable 'p' to silence this warning
void *p; // @17
^
= 0
C++11: note: initialize the variable 'p' to silence this warning
void *p; // @11
^
= nullptr
note: initialize the variable 'p' to silence this warning
void *p; // @17
^
= nullptr
Since this test is meant to test macro undef behavior and that the C++11 fix-it diagnostics can not distinguish between the macro being defined to “NULL” vs being undefined (nullptr in both cases), I have restricted this test to C++98.
Cheers,
Charles Li
https://reviews.llvm.org/D24812
Files:
test/CodeGenCXX/arm.cpp
test/CodeGenCXX/debug-info-class.cpp
test/CodeGenCXX/eh-aggregate-copy-destroy.cpp
test/CodeGenCXX/exceptions.cpp
test/CodeGenCXX/goto.cpp
test/CodeGenCXX/linetable-cleanup.cpp
test/CodeGenCXX/lpad-linetable.cpp
test/CodeGenCXX/mangle-unnamed.cpp
test/CodeGenCXX/static-init.cpp
test/CodeGenCXX/value-init.cpp
test/CodeGenCXX/volatile-1.cpp
test/CodeGenCXX/volatile.cpp
test/Index/comment-cplus-decls.cpp
test/OpenMP/atomic_codegen.cpp
test/OpenMP/threadprivate_codegen.cpp
test/PCH/macro-undef.cpp
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