This is extended to all `std::` functions that take a reference to a
value and return a reference (or pointer) to that same value: `move`,
`forward`, `move_if_noexcept`, `as_const`, `addressof`, and the
libstdc++-specific function `__addressof`.
We still require these functions to be declared before they can be used,
but don't instantiate their definitions unless their addresses are
taken. Instead, code generation, constant evaluation, and static
analysis are given direct knowledge of their effect.
This change aims to reduce various costs associated with these functions
-- per-instantiation memory costs, compile time and memory costs due to
creating out-of-line copies and inlining them, code size at -O0, and so
on -- so that they are not substantially more expensive than a cast.
Most of these improvements are very small, but I measured a 3% decrease
in -O0 object file size for a simple C++ source file using the standard
library after this change.
We now automatically infer the `const` and `nothrow` attributes on these
now-builtin functions, in particular meaning that we get a warning for
an unused call to one of these functions.
In C++20 onwards, we disallow taking the addresses of these functions,
per the C++20 "addressable function" rule. In earlier language modes, a
compatibility warning is produced but the address can still be taken.
The same infrastructure is extended to the existing MSVC builtin
`__GetExceptionInfo`, which is now only recognized in namespace `std`
like it always should have been.
This is a re-commit of
fc30901096,
a571f82a50, and
64c045e25b
which were reverted in
e75d8b7037
due to a crasher bug where CodeGen would emit a builtin glvalue as an
rvalue if it constant-folds.
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D123345
A randomized structure needs to use a designated or default initializer.
Using a non-designated initializer will result in values being assigned
to the wrong fields.
Differential Revision: https://reviews.llvm.org/D123763
We still require these functions to be declared before they can be used,
but don't instantiate their definitions unless their addresses are
taken. Instead, code generation, constant evaluation, and static
analysis are given direct knowledge of their effect.
This change aims to reduce various costs associated with these functions
-- per-instantiation memory costs, compile time and memory costs due to
creating out-of-line copies and inlining them, code size at -O0, and so
on -- so that they are not substantially more expensive than a cast.
Most of these improvements are very small, but I measured a 3% decrease
in -O0 object file size for a simple C++ source file using the standard
library after this change.
We now automatically infer the `const` and `nothrow` attributes on these
now-builtin functions, in particular meaning that we get a warning for
an unused call to one of these functions.
In C++20 onwards, we disallow taking the addresses of these functions,
per the C++20 "addressable function" rule. In earlier language modes, a
compatibility warning is produced but the address can still be taken.
The same infrastructure is extended to the existing MSVC builtin
`__GetExceptionInfo`, which is now only recognized in namespace `std`
like it always should have been.
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D123345
A randomized structure needs to use a designated or default initializer.
Using a non-designated initializer will result in values being assigned
to the wrong fields.
Differential Revision: https://reviews.llvm.org/D123763
Flexible array initialization is a C/C++ extension implemented in many
compilers to allow initializing the flexible array tail of a struct type
that contains a flexible array. In clang, this is currently restricted
to C. But this construct is used in the Microsoft SDK headers, so I'd
like to extend it to C++.
For now, this doesn't handle dynamic initialization; probably not hard
to implement, but it's extra code, and I don't think it's necessary for
the expected uses. And we explicitly fail out of constant evaluation.
I've added some additional code to assert that initializers have the
correct size, with or without flexible array init. This might catch
issues unrelated to flexible array init.
Differential Revision: https://reviews.llvm.org/D123649
This implements the following changes:
* AutoType retains sugared deduced-as-type.
* Template argument deduction machinery analyses the sugared type all the way
down. It would previously lose the sugar on first recursion.
* Undeduced AutoType will be properly canonicalized, including the constraint
template arguments.
* Remove the decltype node created from the decltype(auto) deduction.
As a result, we start seeing sugared types in a lot more test cases,
including some which showed very unfriendly `type-parameter-*-*` types.
Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>
Reviewed By: rsmith, #libc, ldionne
Differential Revision: https://reviews.llvm.org/D110216
This implements the following changes:
* AutoType retains sugared deduced-as-type.
* Template argument deduction machinery analyses the sugared type all the way
down. It would previously lose the sugar on first recursion.
* Undeduced AutoType will be properly canonicalized, including the constraint
template arguments.
* Remove the decltype node created from the decltype(auto) deduction.
As a result, we start seeing sugared types in a lot more test cases,
including some which showed very unfriendly `type-parameter-*-*` types.
Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>
Reviewed By: rsmith
Differential Revision: https://reviews.llvm.org/D110216
This implements the following changes:
* AutoType retains sugared deduced-as-type.
* Template argument deduction machinery analyses the sugared type all the way
down. It would previously lose the sugar on first recursion.
* Undeduced AutoType will be properly canonicalized, including the constraint
template arguments.
* Remove the decltype node created from the decltype(auto) deduction.
As a result, we start seeing sugared types in a lot more test cases,
including some which showed very unfriendly `type-parameter-*-*` types.
Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>
Reviewed By: rsmith
Differential Revision: https://reviews.llvm.org/D110216
<string> is currently the highest impact header in a clang+llvm build:
https://commondatastorage.googleapis.com/chromium-browser-clang/llvm-include-analysis.html
One of the most common places this is being included is the APInt.h header, which needs it for an old toString() implementation that returns std::string - an inefficient method compared to the SmallString versions that it actually wraps.
This patch replaces these APInt/APSInt methods with a pair of llvm::toString() helpers inside StringExtras.h, adjusts users accordingly and removes the <string> from APInt.h - I was hoping that more of these users could be converted to use the SmallString methods, but it appears that most end up creating a std::string anyhow. I avoided trying to use the raw_ostream << operators as well as I didn't want to lose having the integer radix explicit in the code.
Differential Revision: https://reviews.llvm.org/D103888
This is a follow up to the "rvalue-to-prvalue" rename at D103720.
Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>
Depends on D103720
Reviewed By: rsmith
Differential Revision: https://reviews.llvm.org/D103933
This renames the expression value categories from rvalue to prvalue,
keeping nomenclature consistent with C++11 onwards.
C++ has the most complicated taxonomy here, and every other language
only uses a subset of it, so it's less confusing to use the C++ names
consistently, and mentally remap to the C names when working on that
context (prvalue -> rvalue, no xvalues, etc).
Renames:
* VK_RValue -> VK_PRValue
* Expr::isRValue -> Expr::isPRValue
* SK_QualificationConversionRValue -> SK_QualificationConversionPRValue
* JSON AST Dumper Expression nodes value category: "rvalue" -> "prvalue"
Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>
Reviewed By: rsmith
Differential Revision: https://reviews.llvm.org/D103720
I recently ran into issues with aggregates and inheritance, I'm using
it for creating a type-safe library where most of the types are build
over "tagged" std::array. After bit of cleaning and enabling -Wall
-Wextra -pedantic I noticed clang only in my pipeline gives me warning.
After a bit of focusing on it I found it's not helpful, and contemplate
disabling the warning all together. After a discussion with other
library authors I found it's bothering more people and decided to fix
it.
Removes this warning:
template<typename T, int N> struct StdArray {
T contents[N];
};
template<typename T, int N> struct AggregateAndEmpty : StdArray<T,N> { };
AggregateAndEmpty<int, 3> p = {1, 2, 3}; // <-- warning here about omitted braces
There is no functional change here (hence no new tests). The only change
is to replace a couple uintptr_t members with llvm::PointerIntPair<> to
clean up the code, making it more readable and less error prone.
This cleanup highlighted that the old code was effectively casting away
const. This is fixed by changing some function signatures.
Reviewed By: rsmith
Differential Revision: https://reviews.llvm.org/D98889
There is no need to check for enabled pragma for core or optional core features,
thus this check is removed
Reviewed By: Anastasia
Differential Revision: https://reviews.llvm.org/D97058
See https://bugs.llvm.org/show_bug.cgi?id=42154.
GCC's __attribute__((align)) can reduce the alignment of a type when applied to
a typedef. However, functions which take a pointer or reference to the
original type are compiled assuming the original alignment. Therefore when any
such function is passed an object of the new, less-aligned type, an alignment
fault can occur. In particular, this applies to the constructor, which is
defined for the original type and called for the less-aligned object.
This change adds a warning whenever an pointer or reference to an object is
passed to a function that was defined for a more-aligned type.
The calls to ASTContext::getTypeAlignInChars seem change the order in which
record layouts are evaluated, which caused changes to the output of
-fdump-record-layouts. As such some tests needed to be updated:
* Use CHECK-LABEL rather than counting the number of "Dumping AST Record
Layout" headers.
* Check for end of line in labels, so that struct B1 doesn't match struct B
etc.
* Add --strict-whitespace, since the whitespace shows meaningful structure.
* The order in which record layouts are printed has changed in some cases.
* clang-format for regions changed
Differential Revision: https://reviews.llvm.org/D97187
This is a corner of the differences between C99 designators and C++20
designators that we'd previously overlooked. As with other such cases,
this continues to be permitted as an extension and allowed by default,
behind the -Wc99-designators warning flag, except in cases where it
leads to a conformance difference (such as in overload resolution and in
a SFINAE context).
Prevent materializing temporaries in the address space of the references
they are bind to. The temporaries should always be in the same address
space - private for OpenCL.
Tags: #clang
Differential Revision: https://reviews.llvm.org/D95608
reference binding to an expression.
We need to know the array bound in order to determine whether the
parameter type is reference-compatible with the argument type, so we
need to trigger instantiation in this case.
Like the VarDecl that gets its type updated based on an init-list, this
patch corrects the MaterializeTemporaryExpr's type to make sure it isn't
creating an incomplete type, which leads to a handful of CodeGen crashes
(see PR 47636).
Based on @rsmith 's comments on D88236
Differential Revision: https://reviews.llvm.org/D88298
In implicitly movable test, a two-stage overload resolution is performed.
If the first overload resolution selects a deleted function, Clang directly
performs the second overload resolution, without checking whether the
deleted function matches the additional criteria.
This patch fixes the above problem.
Reviewed By: Quuxplusone
Differential Revision: https://reviews.llvm.org/D92936
In implicitly movable test, a two-stage overload resolution is performed.
If the first overload resolution selects a deleted function, Clang directly
performs the second overload resolution, without checking whether the
deleted function matches the additional criteria.
This patch fixes the above problem.
Reviewed By: Quuxplusone
Differential Revision: https://reviews.llvm.org/D92936
Technically 'noexcept' isn't a qualifier, so this should be a separate conversion.
Also make the test a pure frontend test.
Reviewed By: rsmith
Differential Revision: https://reviews.llvm.org/D67112
non-type template parameters.
Create a unique TemplateParamObjectDecl instance for each such value,
representing the globally unique template parameter object to which the
template parameter refers.
No IR generation support yet; that will follow in a separate patch.
folding to not constant folding.
Constant folding of ICEs is done as a GCC compatibility measure, but new
code was picking it up, presumably by accident, due to the bad default.
While here, also switch the flag from a bool to an enum to make it more
obvious what it means at call sites. This highlighted a couple of places
where our behavior is different between C++11 and C++14 due to switching
from checking for an ICE to checking for a converted constant
expression (where there is no 'fold' codepath).
The function `TryListConversion` didn't properly validate the following
part of the standard:
Otherwise, if the parameter type is a character array [... ]
and the initializer list has a single element that is an
appropriately-typed string literal (8.5.2 [dcl.init.string]), the
implicit conversion sequence is the identity conversion.
This caused the following call to `f()` to be ambiguous.
void f(int(&&)[1]);
void f(unsigned(&&)[1]);
void g(unsigned i) {
f({i});
}
This issue only occurs when the initializer list had one element.
Differential Revision: https://reviews.llvm.org/D87561
This is recommit of 6c8041aa0f, reverted in de044f7562 because of some
fails. Original commit message is below.
This change allow a CastExpr to have optional FPOptionsOverride object,
stored in trailing storage. Of all cast nodes only ImplicitCastExpr,
CStyleCastExpr, CXXFunctionalCastExpr and CXXStaticCastExpr are allowed
to have FPOptions.
Differential Revision: https://reviews.llvm.org/D85960
This change allow a CastExpr to have optional FPOptionsOverride object,
stored in trailing storage. Of all cast nodes only ImplicitCastExpr,
CStyleCastExpr, CXXFunctionalCastExpr and CXXStaticCastExpr are allowed
to have FPOptions.
Differential Revision: https://reviews.llvm.org/D85960
- Prevent nullptr-deference at try to emit warning for invalid `expr`
- Simplify `InitListChecker::UpdateStructuredListElement()` usages. We do not need to check `expr` and increment `StructuredIndex` (for invalid `expr`) before the call anymore.
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D85193
When a semantic checking fails on a syntactic InitListExpr, we will
get an ill-formed semantic InitListExpr (e.g. some inits are nullptr),
using this semantic InitListExpr in clang (without setting the err-bits) is crashy.
Differential Revision: https://reviews.llvm.org/D84140
__builtin_va_*() and __builtin_ms_va_*() are declared as functions with a
parameter of reference type.
This patch fixes a crash when using these functions in C where an argument
of structure type is incompatible with the parameter type.
Differential Revision: https://reviews.llvm.org/D82805
Reviewed By: riccibruno
Patch by: Aleksandr Platonov <platonov.aleksandr@huawei.com>
`noderef` was failing to trigger warnings in some cases related to c++ style
casting. This patch addresses them.
Differential Revision: https://reviews.llvm.org/D77836
Richard Smith