The ``disable_tail_calls`` attribute instructs the backend to not
perform tail call optimization inside the marked function.
For example,
int callee(int);
int foo(int a) __attribute__((disable_tail_calls)) {
return callee(a); // This call is not tail-call optimized.
}
Note that this attribute is different from 'not_tail_called', which
prevents tail-call optimization to the marked function.
rdar://problem/8973573
Differential Revision: http://reviews.llvm.org/D12547
llvm-svn: 252986
declarations in redeclaration lookup. A declaration is now visible to
lookup if:
* It is visible (not in a module, or in an imported module), or
* We're doing redeclaration lookup and it's externally-visible, or
* We're doing typo correction and looking for unimported decls.
We now support multiple modules having different internal-linkage or no-linkage
definitions of the same name for all entities, not just for functions,
variables, and some typedefs. As previously, if multiple such entities are
visible, any attempt to use them will result in an ambiguity error.
This patch fixes the linkage calculation for a number of entities where we
previously didn't need to get it right (using-declarations, namespace aliases,
and so on). It also classifies enumerators as always having no linkage, which
is a slight deviation from the C++ standard's definition, but not an observable
change outside modules (this change is being discussed on the -core reflector
currently).
This also removes the prior special case for tag lookup, which made some cases
of this work, but also led to bizarre, bogus "must use 'struct' to refer to type
'Foo' in this scope" diagnostics in C++.
llvm-svn: 252960
DR407, the C++ standard doesn't really say how this should work. Here's what we
do (which is consistent with DR407 as far as I can tell):
* When performing name lookup for an elaborated-type-specifier, a tag
declaration hides a typedef declaration that names the same type.
* When performing any other kind of lookup, a typedef declaration hides
a tag declaration that names the same type.
In any other case where lookup finds both a typedef and a tag (that is, when
they name different types), the lookup will be ambiguous. If lookup finds a
tag and a typedef that name the same type, and finds anything else, the lookup
will always be ambiguous (even if the other entity would hide the tag, it does
not also hide the typedef).
llvm-svn: 252959
This failed to solve the problem it was aimed at, and introduced just as many
issues as it resolved. Realistically, we need to deal with the possibility that
multiple modules might define different internal linkage symbols with the same
name, and this isn't a problem unless two such symbols are simultaneously
visible.
The case where two modules define equivalent internal linkage symbols is
handled by r252063: if lookup finds multiple sufficiently-similar entities from
different modules, we just pick one of them as an extension (but we keep them
separate).
llvm-svn: 252957
https://gcc.gnu.org/onlinedocs/gcc/Typeof.html
Differences from the GCC extension:
* __auto_type is also permitted in C++ (but only in places where
it could appear in C), allowing its use in headers that might
be shared across C and C++, or used from C++98
* __auto_type can be combined with a declarator, as with C++ auto
(for instance, "__auto_type *p")
* multiple variables can be declared in a single __auto_type
declaration, with the C++ semantics (the deduced type must be
the same in each case)
This patch also adds a missing restriction on applying typeof to
a bit-field, which GCC has historically rejected in C (due to
lack of clarity as to whether the operand should be promoted).
The same restriction also applies to __auto_type in C (in both
GCC and Clang).
This also fixes PR25449.
Patch by Nicholas Allegra!
llvm-svn: 252690
std::initializer_list<T> type. Instead, the list must contain a single element
and the type is deduced from that.
In Clang 3.7, we warned by default on all the cases that would change meaning
due to this change. In Clang 3.8, we will support only the new rules -- per
the request in N3922, this change is applied as a Defect Report against earlier
versions of the C++ standard.
This change is not entirely trivial, because for lambda init-captures we
previously did not track the difference between direct-list-initialization and
copy-list-initialization. The difference was not previously observable, because
the two forms of initialization always did the same thing (the elements of the
initializer list were always copy-initialized regardless of the initialization
style used for the init-capture).
llvm-svn: 252688
The attrubite is applicable to functions and variables and changes
the linkage of the subject to internal.
This is the same functionality as C-style "static", but applicable to
class methods; and the same as anonymouns namespaces, but can apply
to individual methods of a class.
Following the proposal in
http://lists.llvm.org/pipermail/cfe-dev/2015-October/045580.html
llvm-svn: 252648
This attribute is used to prevent tail-call optimizations to the marked
function. For example, in the following piece of code, foo1 will not be
tail-call optimized:
int __attribute__((not_tail_called)) foo1(int);
int foo2(int a) {
return foo1(a); // Tail-call optimization is not performed.
}
The attribute has effect only on statically bound calls. It has no
effect on indirect calls. Also, virtual functions and objective-c
methods cannot be marked as 'not_tail_called'.
rdar://problem/22667622
Differential Revision: http://reviews.llvm.org/D12922
llvm-svn: 252369
internal linkage entities in different modules from r250884 to apply to all
names, not just function names.
This is really awkward: we don't want to merge internal-linkage symbols from
separate modules, because they might not actually be defining the same entity.
But we don't want to reject programs that use such an ambiguous symbol if those
internal-linkage symbols are in fact equivalent. For now, we're resolving the
ambiguity by picking one of the equivalent definitions as an extension.
llvm-svn: 252063
Summary: Diagnose when the 'concept' specifier is used on a typedef or function parameter.
Reviewers: rsmith, hubert.reinterpretcast, aaron.ballman, faisalv
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D14316
llvm-svn: 252061
This new builtin template allows for incredibly fast instantiations of
templates like std::integer_sequence.
Performance numbers follow:
My work station has 64 GB of ram + 20 Xeon Cores at 2.8 GHz.
__make_integer_seq<std::integer_sequence, int, 90000> takes 0.25
seconds.
std::make_integer_sequence<int, 90000> takes unbound time, it is still
running. Clang is consuming gigabytes of memory.
Differential Revision: http://reviews.llvm.org/D13786
llvm-svn: 252036
Now that the properties created within Objective-C class extensions go
into the extension themselves, we don't need any of the extra
complexity here.
llvm-svn: 251949
particular don't assume that two declarations of the same kind in the same
context are declaring the same entity. That's not true when the same name is
declared multiple times as internal-linkage symbols within a module.
(getCanonicalDecl is cheap now, so we can just use it here.)
llvm-svn: 251898
A 'readonly' Objective-C property declared in the primary class can
effectively be shadowed by a 'readwrite' property declared within an
extension of that class, so long as the types and attributes of the
two property declarations are compatible.
Previously, this functionality was implemented by back-patching the
original 'readonly' property to make it 'readwrite', destroying source
information and causing some hideously redundant, incorrect
code. Simplify the implementation to express how this should actually
be modeled: as a separate property declaration in the extension that
shadows (via the name lookup rules) the declaration in the primary
class. While here, correct some broken Fix-Its, eliminate a pile of
redundant code, clean up the ARC migrator's handling of properties
declared in extensions, and fix debug info's naming of methods that
come from categories.
A wonderous side effect of doing this write is that it eliminates the
"AddedObjCPropertyInClassExtension" method from the AST mutation
listener, which in turn eliminates the last place where we rewrite
entire declarations in a chained PCH file or a module file. This
change (which fixes rdar://problem/18475765) will allow us to
eliminate the rewritten-decls logic from the serialization library,
and fixes a crash (rdar://problem/23247794) illustrated by the
test/PCH/chain-categories.m example.
llvm-svn: 251874
We permit implicit conversion from pointer-to-function to
pointer-to-object when -fms-extensions is specified. This is rather
unfortunate, move this into -fms-compatibility and only permit it within
system headers unless -Wno-error=microsoft-cast is specified.
llvm-svn: 251738
Handle blocks in the tree transform for the typo correction as otherwise, the
capture may miss. This would trigger an assertion. Thanks to Doug Gregor for
the help with this!
Fixes PR25001.
llvm-svn: 251729
GCC has a warning called -Wdouble-promotion, which warns you when
an implicit conversion increases the width of a floating point type.
This is useful when writing code for architectures that can perform
hardware FP ops on floats, but must fall back to software emulation for
larger types (i.e. double, long double).
This fixes PR15109 <https://llvm.org/bugs/show_bug.cgi?id=15109>.
Thanks to Carl Norum for the patch!
llvm-svn: 251588
Fake arguments are automatically handled for serialization, cloning,
and other representational tasks, but aren't included in pretty-printing
or parsing (should we eventually ever automate that).
This is chiefly useful for attributes that can be written by the
user, but which are also frequently synthesized by the compiler,
and which we'd like to remember details of the synthesis for.
As a simple example, use this to narrow the cases in which we were
generating a specialized note for implicitly unavailable declarations.
llvm-svn: 251469
1. Make the warning more strict in C mode. r172696 added code to suppress
warnings from macro expansions in system headers, which checks
`SourceMgr.isMacroBodyExpansion(E->IgnoreParens()->getExprLoc())`. Consider
this snippet:
#define FOO(x) (x)
void f(int a) {
FOO(a);
}
In C, the line `FOO(a)` is an `ImplicitCastExpr(ParenExpr(DeclRefExpr))`,
while it's just a `ParenExpr(DeclRefExpr)` in C++. So in C++,
`E->IgnoreParens()` returns the `DeclRefExpr` and the check tests the
SourceLoc of `a`. In C, the `ImplicitCastExpr` has the effect of checking the
SourceLoc of `FOO`, which is a macro body expansion, which causes the
diagnostic to be skipped. It looks unintentional that clang does different
things for C and C++ here, so use `IgnoreParenImpCasts` instead of
`IgnoreParens` here. This has the effect of the warning firing more often
than previously in C code – it now fires as often as it fires in C++ code.
2. Suppress the warning if it would warn on `UNREFERENCED_PARAMETER`.
`UNREFERENCED_PARAMETER` is a commonly used macro on Windows and it happens
to uselessly trigger -Wunused-value. As discussed in the thread
"rfc: winnt.h's UNREFERENCED_PARAMETER() vs clang's -Wunused-value" on
cfe-dev, fix this by special-casing this specific macro. (This costs a string
comparison and some fast-path lexing per warning, but the warning is emitted
rarely. It fires once in Windows.h itself, so this code runs at least once
per TU including Windows.h, but it doesn't run hundreds of times.)
http://reviews.llvm.org/D13969
llvm-svn: 251441
allow them to be written in certain kinds of user declaration and
diagnose on the use-site instead.
Also, improve and fix some diagnostics relating to __weak and
properties.
rdar://23228631
llvm-svn: 251384
Summary:
In `MismatchingNewDeleteDetector::analyzeInClassInitializer`, if
`Field`'s initializer expression is null, lookup the field in
implicit instantiation, and use found field's the initializer.
Reviewers: rsmith, rtrieu
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D9898
llvm-svn: 251335
Previously, __weak was silently accepted and ignored in MRC mode.
That makes this a potentially source-breaking change that we have to
roll out cautiously. Accordingly, for the time being, actual support
for __weak references in MRC is experimental, and the compiler will
reject attempts to actually form such references. The intent is to
eventually enable the feature by default in all non-GC modes.
(It is, of course, incompatible with ObjC GC's interpretation of
__weak.)
If you like, you can enable this feature with
-Xclang -fobjc-weak
but like any -Xclang option, this option may be removed at any point,
e.g. if/when it is eventually enabled by default.
This patch also enables the use of the ARC __unsafe_unretained qualifier
in MRC. Unlike __weak, this is being enabled immediately. Since
variables are essentially __unsafe_unretained by default in MRC,
the only practical uses are (1) communication and (2) changing the
default behavior of by-value block capture.
As an implementation matter, this means that the ObjC ownership
qualifiers may appear in any ObjC language mode, and so this patch
removes a number of checks for getLangOpts().ObjCAutoRefCount
that were guarding the processing of these qualifiers. I don't
expect this to be a significant drain on performance; it may even
be faster to just check for these qualifiers directly on a type
(since it's probably in a register anyway) than to do N dependent
loads to grab the LangOptions.
rdar://9674298
llvm-svn: 251041
headers. If those headers end up being textually included twice into the same
module, we get ambiguity errors.
Work around this by downgrading the ambiguity error to a warning if multiple
identical internal-linkage functions appear in an overload set, and just pick
one of those functions as the lookup result.
llvm-svn: 250884
This time, I went with the first approach from
http://reviews.llvm.org/D6700, where clang actually attempts to form an
implicit member reference from an UnresolvedLookupExpr. We know that
there are only two possible outcomes at this point, a DeclRefExpr of the
FieldDecl or an error, but its safer to reuse the existing machinery for
this.
llvm-svn: 250856
Microsoft's ATL headers make use of this MSVC extension, add support for
it and issue a diagnostic under -Wmicrosoft-exception-spec.
This fixes PR25265.
llvm-svn: 250854
Akira Hatanaka