This attribute may be attached to a function definition and instructs the backend to generate appropriate function entry/exit code so that
it can be used directly as an interrupt handler.
The IRET instruction, instead of the RET instruction, is used to return from interrupt or exception handlers. All registers, except for the EFLAGS register which is restored by the IRET instruction, are preserved by the compiler.
Any interruptible-without-stack-switch code must be compiled with -mno-red-zone since interrupt handlers can and will, because of the hardware design, touch
the red zone.
interrupt handler must be declared with a mandatory pointer argument:
struct interrupt_frame;
__attribute__ ((interrupt))
void f (struct interrupt_frame *frame) {
...
}
and user must properly define the structure the pointer pointing to.
exception handler:
The exception handler is very similar to the interrupt handler with a different mandatory function signature:
#ifdef __x86_64__
typedef unsigned long long int uword_t;
#else
typedef unsigned int uword_t;
#endif
struct interrupt_frame;
__attribute__ ((interrupt))
void f (struct interrupt_frame *frame, uword_t error_code) {
...
}
and compiler pops the error code off stack before the IRET instruction.
The exception handler should only be used for exceptions which push an error code and all other exceptions must use the interrupt handler.
The system will crash if the wrong handler is used.
Differential Revision: http://reviews.llvm.org/D15709
llvm-svn: 257867
redeclares an existing tag but are creating a new declaration anyway (because
it has attributes or changes the visibility of the name), don't warn that it
won't be visible outside the current scope. That's not true.
Also narrow down the set of cases where we create these extra declarations when
building modules; previously, all tag declarations but the first in a module
header would get this treatment if -fmodules-local-submodule-visibility. (This
isn't a functional change, but we try to avoid creating these extra
declarations whenever we can.)
llvm-svn: 257403
Given an expression like `(&Foo)();`, we perform overload resolution as
if we are calling `Foo` directly. This causes problems if `Foo` is a
function that can't have its address taken. This patch teaches overload
resolution to ignore functions that can't have their address taken in
such cases.
Differential Revision: http://reviews.llvm.org/D15590
llvm-svn: 257016
Summary:
There are a number of files in the tree which have been accidentally checked in with DOS line endings. Convert these to native line endings.
There are also a few files which have DOS line endings on purpose, and I have set the svn:eol-style property to 'CRLF' on those.
Reviewers: joerg, aaron.ballman
Subscribers: aaron.ballman, cfe-commits
Differential Revision: http://reviews.llvm.org/D15849
llvm-svn: 256704
If there are two pointers passed to an atomic Builtin,
Clang doesn't allow the second (non-atomic) one to be qualified
with an address space.
Remove this restriction by recording the address space of passed pointers
in atomics type diagnostics.
llvm-svn: 256243
Given the following code:
int *_Nullable ptr;
int *_Nonnull nn = ptr;
...In C, clang will warn you about `nn = ptr`, because you're assigning
a nonnull pointer to a nullable pointer. In C++, clang issues no such
warning. This patch helps ensure that clang doesn't ever miss an
opportunity to complain about C++ code.
N.B. Though this patch has a differential revision link, the actual
review took place over email.
Differential Revision: http://reviews.llvm.org/D14938
llvm-svn: 255556
Currently, we emit warnings in some cases where nonnull function
parameters are compared against null. This patch extends this support
to warn when comparing the result of `returns_nonnull` functions
against null.
More specifically, we will now warn cases like:
int *foo() __attribute__((returns_nonnull));
int main() {
if (foo() == NULL) {} // warning: will always evaluate to false
}
Differential Revision: http://reviews.llvm.org/D15324
llvm-svn: 255058
variables in C, in the cases where we can constant-fold it to a value
regardless (such as floating-point division by zero and signed integer
overflow). Strictly enforcing this rule breaks too much code.
llvm-svn: 254992
The introduction of pass_object_size fixed a few bugs related to taking
the address of a function with enable_if attributes. This patch adds
tests for the cases that were fixed.
llvm-svn: 254646
These additions were meant to go in as a part of r254554; while it's
certainly nice to have new functionality, it's nicer if we have tests to
go with it. :)
llvm-svn: 254632
This reverts commit r254143 which introduces a crash on the following input:
f(char *);
g(char *);
#pragma weak f = g
int g(char *p) {}
llvm-svn: 254605
This CL is for discussion how to better fix bit-filed layout compatibility issue with GCC (see PR25575 for test case and more details). Current clang behavior is compatible with GCC 4.1-4.3 series but it was fixed in 4.4+. Ignoring packed attribute looks very odd and because it was also fixed in GCC 4.4+, it makes sense also fix it in clang.
Differential Revision: http://reviews.llvm.org/D14872
llvm-svn: 254596
side-effect, so that we don't allow speculative evaluation of such expressions
during code generation.
This caused a diagnostic quality regression, so fix constant expression
diagnostics to prefer either the first "can't be constant folded" diagnostic or
the first "not a constant expression" diagnostic depending on the kind of
evaluation we're doing. This was always the intent, but didn't quite work
correctly before.
This results in certain initializers that used to be constant initializers to
no longer be; in particular, things like:
float f = 1e100;
are no longer accepted in C. This seems appropriate, as such constructs would
lead to code being executed if sanitizers are enabled.
llvm-svn: 254574
Summary: This patch adds support for the interrupt attribute for mips32r2+.
Patch by Simon Dardis.
Reviewers: dsanders, aaron.ballman
Subscribers: aaron.ballman, cfe-commits
Differential Revision: http://reviews.llvm.org/D10802
llvm-svn: 254205
Summary: This patch adds support for the interrupt attribute for mips32r2+.
Reviewers: dsanders, aaron.ballman
Subscribers: aaron.ballman, cfe-commits
Differential Revision: http://reviews.llvm.org/D10802
llvm-svn: 254203
For MCU only C calling convention is allowed, all other calling conventions are not supported.
Differential Revision: http://reviews.llvm.org/D14864
llvm-svn: 254063
Summary: 's' is used to specify sgprs and 'v' is used to specify vgprs.
Reviewers: arsenm, echristo
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D14307
llvm-svn: 253610
Add support for vector mode attributes like "attribute((mode(V4SF)))". Also add warning about deprecated vector modes like GCC does.
Differential Revision: http://reviews.llvm.org/D14744
llvm-svn: 253551
Currently, when there is a global register variable in a program that
is bound to an invalid register, clang/llvm prints an error message that
is not very user-friendly.
This commit improves the diagnostic and moves the check that used to be
in the backend to Sema. In addition, it makes changes to error out if
the size of the register doesn't match the declared variable size.
e.g., volatile register int B asm ("rbp");
rdar://problem/23084219
Differential Revision: http://reviews.llvm.org/D13834
llvm-svn: 253405
Clang tries to figure out if a call to abs is suspicious by looking
through implicit casts to look at the underlying, implicitly converted
type.
Interestingly, C has implicit conversions from pointer-ish types like
function to less exciting types like int. This trips up our 'abs'
checker because it doesn't know which variant of 'abs' is appropriate.
Instead, diagnose 'abs' called on function types upfront. This sort of
thing is highly suspicious and is likely indicative of a missing
pointer dereference/function call/array index operation.
This fixes PR25532.
llvm-svn: 253156
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
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
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
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
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
Previously, our logic when taking the address of an overloaded function
would not consider enable_if attributes, so long as all of the enable_if
conditions on a given candidate were true. So, two functions with
identical signatures (one with enable_if attributes, the other without),
would be considered equally good overloads. If we were calling the
function instead of taking its address, then the function with enable_if
attributes would be preferred.
This patch makes us prefer the candidate with enable_if regardless of if
we're calling or taking the address of an overloaded function.
Differential Revision: http://reviews.llvm.org/D13795
llvm-svn: 250486
This fixes a bug where one can take the address of a conditionally
enabled function to drop its enable_if guards. For example:
int foo(int a) __attribute__((enable_if(a > 0, "")));
int (*p)(int) = &foo;
int result = p(-1); // compilation succeeds; calls foo(-1)
Overloading logic has been updated to reflect this change, as well.
Functions with enable_if attributes that are always true are still
allowed to have their address taken.
Differential Revision: http://reviews.llvm.org/D13607
llvm-svn: 250090
C allows for some implicit conversions that C++ does not, e.g. void* ->
char*. This patch teaches clang that these conversions are okay when
dealing with overloads in C.
Differential Revision: http://reviews.llvm.org/D13604
llvm-svn: 249995
Summary:
Currently when a function annotated with __attribute__((nonnull)) is called in an unevaluated context with a null argument a -Wnonnull warning is emitted.
This warning seems like a false positive unless the call expression is potentially evaluated. Change this behavior so that the non-null warnings use DiagRuntimeBehavior so they wont emit when they won't be evaluated.
Reviewers: majnemer, rsmith
Subscribers: mclow.lists, cfe-commits
Differential Revision: http://reviews.llvm.org/D13408
llvm-svn: 249787
consider the following:
enum E *p;
enum E { e };
The above snippet is not ANSI C because 'enum E' has not bee defined
when we are processing the declaration of 'p'; however, it is a popular
extension to make the above work. This would fail using the Microsoft
enum semantics because the definition of 'E' would implicitly have a
fixed underlying type of 'int' which would trigger diagnostic messages
about a mismatch between the declaration and the definition.
Instead, treat fixed underlying types as not fixed for the purposes of
the diagnostic.
llvm-svn: 249674
Our self hosting buildbots found a few more tests which weren't updated
to reflect that the enum semantics are part of the Microsoft ABI.
llvm-svn: 249670
Enums without an explicit, fixed, underlying type are implicitly given a
fixed 'int' type for ABI compatibility with MSVC. However, we can
enforce the standard-mandated rules on these types as-if we didn't know
this fact if the tag is not part of a definition.
llvm-svn: 249667
These test updates almost exclusively around the change in behavior
around enum: enums without a definition are considered incomplete except
when targeting MSVC ABIs. Since these tests are interested in the
'incomplete-enum' behavior, restrict them to %itanium_abi_triple.
llvm-svn: 249660
Diagnose when a pointer to const T is used as the first argument in at atomic
builtin unless that builtin is a load operation. This is already checked for
C11 atomics builtins but not for __atomic ones.
This patch was given the LGTM by rsmith when it was part
of a larger review. (See http://reviews.llvm.org/D10407)
llvm-svn: 249252
Prior to this patch, -Wtautological-overlap-compare would only warn us
if there was a sketchy logical comparison between variables and
IntegerLiterals. This patch makes -Wtautological-overlap-compare aware
of EnumConstantDecls, so it can apply the same logic to them.
llvm-svn: 249053
Several inputs may not refer to one output constraint in inline assembler
insertions, clang was failing on assertion on such test case.
llvm-svn: 248158
Summary:
This change adds support for `__builtin_ms_va_list`, a GCC extension for
variadic `ms_abi` functions. The existing `__builtin_va_list` support is
inadequate for this because `va_list` is defined differently in the Win64
ABI vs. the System V/AMD64 ABI.
Depends on D1622.
Reviewers: rsmith, rnk, rjmccall
CC: cfe-commits
Differential Revision: http://reviews.llvm.org/D1623
llvm-svn: 247941
Previously, in certain cases lax vector conversions could occur between scalar floating-point values and ExtVector types; these conversions would be simple bitcasts. We need to allow them with other vector types to support some common headers, but we don't need them for ExtVector. Preventing them here makes them behave like other operations involving scalars and ExtVectors.
llvm-svn: 247643
We were crashing in CodeGen given input like this:
int self_alias(void) __attribute__((weak, alias("self_alias")));
such a self-alias is invalid, but instead of diagnosing the situation, we'd
proceed to produce IR for both the function declaration and the alias. Because
we already had a function named 'self_alias', the alias could not be named the
same thing, and so LLVM would pick a different name ('self_alias1' for example)
for that value. When we later called CodeGenModule::checkAliases, we'd look up
the IR value corresponding to the alias name, find the function declaration
instead, and then assert in a cast to llvm::GlobalAlias. The easiest way to prevent
this is simply to avoid creating the wrongly-named alias value in the first
place and issue the diagnostic there (instead of in checkAliases). We detect a
related cycle case in CodeGenModule::EmitAliasDefinition already, so this just
adds a second such check.
Even though the other test cases for this 'alias definition is part of a cycle'
diagnostic are in test/Sema/attr-alias-elf.c, I've added a separate regression
test for this case. This is because I can't add this check to
test/Sema/attr-alias-elf.c without disturbing the other test cases in that
file. In order to avoid construction of the bad IR values, this diagnostic
is emitted from within CodeGenModule::EmitAliasDefinition (and the relevant
declaration is not added to the Aliases vector). The other cycle checks are
done within the CodeGenModule::checkAliases function based on the Aliases
vector, called from CodeGenModule::Release. However, if there have been errors
earlier, HandleTranslationUnit does not call Release, and so checkAliases is
never called, and so none of the other diagnostics would be produced.
Fixes PR23509.
llvm-svn: 246882
They might technically have external linkage, but it still doesn't make sense
for the user to try and export such variables. This matches MSVC's and MinGW's
behaviour.
llvm-svn: 246864
We cannot tell if an object is past-the-end if its type is incomplete.
Zero sized objects satisfy past-the-end criteria and our object might
turn out to be such an object.
This fixes PR24622.
llvm-svn: 246359
The problem is that the arguments are of TheCall are reset later
to the ones in Args, making TypoExpr put back. Some TypoExpr that have
already been diagnosed and will assert later in Sema::getTypoExprState
llvm-svn: 245560
alignment is ignored, and they always allocate a complete
storage unit.
Also, change the dumping of AST record layouts: use the more
readable C++-style dumping even in C, include bitfield offset
information in the dump, and don't print sizeof/alignof
information for fields of record type, since we don't do so
for bases or other kinds of field.
rdar://22275433
llvm-svn: 245514
Remove the assumption of a Boolean type by checking if an expression is known
to have a boolean value. Disable warning in two other tests.
llvm-svn: 245507
__builtin_object_size would return incorrect answers for many uses where
type=3. This fixes the inaccuracy by making us emit 0 instead of LLVM's
objectsize intrinsic.
Additionally, there are many cases where we would emit suboptimal (but
correct) answers, such as when arrays are involved. This patch fixes
some of these cases (please see new tests in test/CodeGen/object-size.c
for specifics on which cases are improved)
Resubmit of r245323 with PR24493 fixed.
Patch mostly by Richard Smith.
Differential Revision: http://reviews.llvm.org/D12000
This fixes PR15212.
llvm-svn: 245403
__builtin_object_size would return incorrect answers for many uses where
type=3. This fixes the inaccuracy by making us emit 0 instead of LLVM's
objectsize intrinsic.
Additionally, there are many cases where we would emit suboptimal (but
correct) answers, such as when arrays are involved. This patch fixes
some of these cases (please see new tests in test/CodeGen/object-size.c
for specifics on which cases are improved)
Patch mostly by Richard Smith.
Differential Revision: http://reviews.llvm.org/D12000
This fixes PR15212.
llvm-svn: 245323
So, we now reject that. We also warn for any external-linkage global
variable named main in C, because it results in undefined behavior.
PR: 24309
Differential Revision: http://reviews.llvm.org/D11658
Reviewed by: rsmith
llvm-svn: 245051
Compiler crashed when vector elements / global register vars were used in inline assembler with "m" restriction. This patch fixes this.
Differential Revision: http://reviews.llvm.org/D10476
llvm-svn: 243870
The z13 vector facility has an associated language extension,
closely modeled on AltiVec/VSX. The main differences are:
- vector long, vector float and vector pixel are not supported
- vector long long and vector double are supported (like VSX)
- comparison operators return a vector rather than a scalar integer
- shift operators behave like the OpenCL shift operators
- vector bool is only supported as argument to certain operators;
some operators allow mixing a bool with a non-bool vector
This patch adds clang support for the extension. It is closely modelled
on the AltiVec support. Similarly to the -faltivec option, there's a
new -fzvector option to enable the extensions (as well as an -mzvector
alias for compatibility with GCC). There's also a separate LangOpt.
The extension as implemented here is intended to be compatible with
the -mzvector extension recently implemented by GCC.
Based on a patch by Richard Sandiford.
Differential Revision: http://reviews.llvm.org/D11001
llvm-svn: 243642
There is currently no support in MSVC for using i128 as an integer
literal suffix. In fact, there appears to be no evidence that they have
ever supported this feature in any of their compilers. This was an over
generalization of their actual feature and is a nasty source of bugs.
Why is it a source of bugs? Because most code in clang expects that
evaluation of an integer constant expression won't give them something
that 'long long' can't represent. Instead of providing a meaningful
feature, i128 gives us cute ways of exploding the compiler.
llvm-svn: 243243
to consider the storage size of the vector instead of its
sizeof. In other words, ban <3 x int> to <4 x int> casts,
which produced invalid IR anyway.
Also, attempt to be a little more rigorous, or at least
explicit, about when enums are allowed in these casts.
rdar://21901132
llvm-svn: 243069
can be different from the normal variable maximum.
Add an error diagnostic for when TLS variables exceed maximum TLS alignment.
Currenty only PS4 sets an explicit maximum TLS alignment.
Patch by Charles Li!
llvm-svn: 242198
We referred to all declaration in definitions in our diagnostic messages
which is can be inaccurate. Instead, classify the declaration and emit
an appropriate diagnostic for the new declaration and an appropriate
note pointing to the old one.
This fixes PR24116.
llvm-svn: 242190
Attribute names usually support an alternate spelling that uses double
underscores before and after the attribute name, like e.g. attribute
((__aligned__)) for attribute ((aligned)). This is necessary to allow
use of attributes in system headers without polluting the name space.
However, for attribute ((enable_if)) that alternate spelling does not
work correctly. This is because of code in Parser::ParseGNUAttributeArgs
(ParseDecl.cpp) that specifically checks for the "enable_if" spelling
without allowing the alternate spelling.
Similar code in ParseDecl.cpp uses the normalizeAttrName helper to allow
both spellings. This patch adds use of that helper for the "enable_if"
check as well, which fixes attribute ((__enable_if__)).
Differential Revision: http://reviews.llvm.org/D11142
llvm-svn: 242029
This matches the implementation of the gcc support for the same
feature, including checking the values set up by libgcc at runtime.
The structure looks like this:
unsigned int __cpu_vendor;
unsigned int __cpu_type;
unsigned int __cpu_subtype;
unsigned int __cpu_features[1];
with a set of enums to match various fields that are field out after
parsing the output of the cpuid instruction.
This also adds a set of errors checking for valid input (and cpu).
compiler-rt support for this and the other builtins in this family
(__builtin_cpu_init and __builtin_cpu_is) are forthcoming.
llvm-svn: 240994
Several tests wouldn't pass when executed on an armv7a_pc_linux triple
due to the non-default arm_aapcs calling convention produced on the
function definitions in the IR output. Account for this with the
application of a little regex.
Patch by Ying Yi.
llvm-svn: 240971
Addresses a conflict with glibc's __nonnull macro by renaming the type
nullability qualifiers as follows:
__nonnull -> _Nonnull
__nullable -> _Nullable
__null_unspecified -> _Null_unspecified
This is the major part of rdar://problem/21530726, but does not yet
provide the Darwin-specific behavior for the old names.
llvm-svn: 240596
The ARM _MoveToCoprocessor and _MoveFromCoprocessor builtins require
integer constants for most arguments, but clang was not checking that.
With this change, we now report meaningful errors instead of crashing
in the backend.
llvm-svn: 240463
Regular function calls (such as to cabs()) run into the same problem
with handling dependent exprs, not just builtins with custom type
checking.
Fixes PR23775.
llvm-svn: 240443
This generalizes the checking of null arguments to also work with
values of pointer-to-function, reference-to-function, and block
pointer type, using the nullability information within the underling
function prototype to extend non-null checking, and diagnoses returns
of 'nil' within a function with a __nonnull return type.
Note that we don't warn about nil returns from Objective-C methods,
because it's common for Objective-C methods to mimic the nil-swallowing
behavior of the receiver by checking ostensibly non-null parameters
and returning nil from otherwise non-null methods in that
case.
It also diagnoses (via a separate flag) conversions from nullable to
nonnull pointers. It's a separate flag because this warning can be noisy.
llvm-svn: 240153
Introduces the type specifiers __nonnull, __nullable, and
__null_unspecified that describe the nullability of the pointer type
to which the specifier appertains. Nullability type specifiers improve
on the existing nonnull attributes in a few ways:
- They apply to types, so one can represent a pointer to a non-null
pointer, use them in function pointer types, etc.
- As type specifiers, they are syntactically more lightweight than
__attribute__s or [[attribute]]s.
- They can express both the notion of 'should never be null' and
also 'it makes sense for this to be null', and therefore can more
easily catch errors of omission where one forgot to annotate the
nullability of a particular pointer (this will come in a subsequent
patch).
Nullability type specifiers are maintained as type sugar, and
therefore have no effect on mangling, encoding, overloading,
etc. Nonetheless, they will be used for warnings about, e.g., passing
'null' to a method that does not accept it.
This is the C/C++ part of rdar://problem/18868820.
llvm-svn: 240146
Alexey Bataev