While at it, add the diagnosis message "left operand of comma operator has no effect" (used by GCC) for comma operator.
This also makes Clang diagnose in the constant evaluation context which aligns with GCC/MSVC behavior. (https://godbolt.org/z/7zxb8Tx96)
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D103938
Currently, linux kernel has a __user attribute ([1]) defined as
__attribute__((noderef, address_space(__user)))
which is used by sparse tool ([2]) to do some
type checking of pointers to user space memory.
During normal compilation, __user will be defined
to nothing so it won't have an impact on compilation.
The btf_tag attribute, which is motivated by
carrying linux kernel annotations into dwarf/BTF,
is introduced in [3]. We intended to define __user as
__attribute__((btf_tag("user")))
so such information will be encoded in dwarf/BTF
and can be used later by bpf verification or other
tracing tools.
But linux kernel __user attribute is also used during
type conversion which btf_tag doesn't support ([4]) since
such type conversion is only used for compiler analysis
and not encoded in dwarf/btf. Theoretically, it is
possible for clang to understand these tags and
do a sparse-like type checking work. But I would like
to leave that to future work and for now suggest simply
ignore these btf_tag attributes if they are used
as type attributes.
[1] https://github.com/torvalds/linux/blob/master/include/linux/compiler_types.h#L10
[2] https://sparse.docs.kernel.org/en/latest/
[3] https://reviews.llvm.org/D106614
[4] https://github.com/torvalds/linux/blob/master/fs/binfmt_flat.c#L135
Differential Revision: https://reviews.llvm.org/D110116
This applies to -Wunused-but-set-variable and
-Wunused-but-set-parameter.
This addresses bug 51865.
Differential Revision: https://reviews.llvm.org/D109862
This improves diagnostic (& important to me, DWARF) accuracy - otherwise
there could be ambiguities between "std::nullptr_t" and some user-defined
type that's /actually/ "nullptr_t" defined in the global namespace.
Differential Revision: https://reviews.llvm.org/D110044
This patch changes the signature of the load and store vector pair
builtins to match their documentation. The type of the `signed long long`
argument is changed to `signed long`. This patch also changes existing testcases
to match the signature change.
Reviewed By: lei, Conanap
Differential Revision: https://reviews.llvm.org/D109996
When building in C mode, the VC runtime assumes that it can use pointer
aliasing through `char *` for the parameter to `__va_start`. Relax the
checks further. In theory we could keep the tests strict for non-system
header code, but this takes the less strict approach as the additional
check doesn't particularly end up being too much more helpful for
correctness. The C++ type system is a bit stricter and requires the
explicit cast which we continue to verify.
While at it, add the diagnosis message "left operand of comma operator has no effect" (used by GCC) for comma operator.
This also makes Clang diagnose in the constant evaluation context which aligns with GCC/MSVC behavior. (https://godbolt.org/z/7zxb8Tx96)
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D103938
\x{XXXX} \u{XXXX} and \o{OOOO} are accepted in all languages mode
in characters and string literals.
This is a feature proposed for both C++ (P2290R1) and C (N2785). The
papers have been seen by both committees but are not yet adopted into
either standard. However, they do have support from both committees.
This patch adds Big-Endian checks for the existing MMA test cases.
It also changes the target for these test cases to pwr10.
Reviewed By: #powerpc, nemanjai
Differential Revision: https://reviews.llvm.org/D109126
Currently, we have no front-end type for ppc_fp128 type in IR. PowerPC
target generates ppc_fp128 type from long double now, but there's option
(-mabi=(ieee|ibm)longdouble) to control it and we're going to do
transition from IBM extended double-double ppc_fp128 to IEEE fp128 in
the future.
This patch adds type __ibm128 which always represents ppc_fp128 in IR,
as what GCC did for that type. Without this type in Clang, compilation
will fail if compiling against future version of libstdcxx (which uses
__ibm128 in headers).
Although all operations in backend for __ibm128 is done by software,
only PowerPC enables support for it.
There's something not implemented in this commit, which can be done in
future ones:
- Literal suffix for __ibm128 type. w/W is suitable as GCC documented.
- __attribute__((mode(IF))) should be for __ibm128.
- Complex __ibm128 type.
Reviewed By: rjmccall
Differential Revision: https://reviews.llvm.org/D93377
The getConstraintRegister method is used by semantic checking of inline
assembly statements in order to diagnose conflicts between clobber list
and input/output lists. By overriding getConstraintRegister we get those
diagnostics and we match RISC-V GCC's behavior. The implementation is
trivial due to the lack of single-register RISC-V-specific constraints.
Differential Revision: https://reviews.llvm.org/D108624
In LLVM IR, `AlignmentBitfieldElementT` is 5-bit wide
But that means that the maximal alignment exponent is `(1<<5)-2`,
which is `30`, not `29`. And indeed, alignment of `1073741824`
roundtrips IR serialization-deserialization.
While this doesn't seem all that important, this doubles
the maximal supported alignment from 512MiB to 1GiB,
and there's actually one noticeable use-case for that;
On X86, the huge pages can have sizes of 2MiB and 1GiB (!).
So while this doesn't add support for truly huge alignments,
which i think we can easily-ish do if wanted, i think this adds
zero-cost support for a not-trivially-dismissable case.
I don't believe we need any upgrade infrastructure,
and since we don't explicitly record the IR version,
we don't need to bump one either.
As @craig.topper speculates in D108661#2963519,
this might be an artificial limit imposed by the original implementation
of the `getAlignment()` functions.
Differential Revision: https://reviews.llvm.org/D108661
Add support for the GNU C style __attribute__((error(""))) and
__attribute__((warning(""))). These attributes are meant to be put on
declarations of functions whom should not be called.
They are frequently used to provide compile time diagnostics similar to
_Static_assert, but which may rely on non-ICE conditions (ie. relying on
compiler optimizations). This is also similar to diagnose_if function
attribute, but can diagnose after optimizations have been run.
While users may instead simply call undefined functions in such cases to
get a linkage failure from the linker, these provide a much more
ergonomic and actionable diagnostic to users and do so at compile time
rather than at link time. Users instead may be able use inline asm .err
directives.
These are used throughout the Linux kernel in its implementation of
BUILD_BUG and BUILD_BUG_ON macros. These macros generally cannot be
converted to use _Static_assert because many of the parameters are not
ICEs. The Linux kernel still needs to be modified to make use of these
when building with Clang; I have a patch that does so I will send once
this feature is landed.
To do so, we create a new IR level Function attribute, "dontcall" (both
error and warning boil down to one IR Fn Attr). Then, similar to calls
to inline asm, we attach a !srcloc Metadata node to call sites of such
attributed callees.
The backend diagnoses these during instruction selection, while we still
know that a call is a call (vs say a JMP that's a tail call) in an arch
agnostic manner.
The frontend then reconstructs the SourceLocation from that Metadata,
and determines whether to emit an error or warning based on the callee's
attribute.
Link: https://bugs.llvm.org/show_bug.cgi?id=16428
Link: https://github.com/ClangBuiltLinux/linux/issues/1173
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D106030
A new attribute btf_tag is added. The syntax looks like
__attribute__((btf_tag(<string>)))
Users may tag a particular structure/member/function/func_parameter/variable
declaration with an arbitrary string and the intention is
that this string is passed to dwarf so it is available for
post-compilation analysis. The string will be also passed
to .BTF section if the target is BPF. For each permitted
declaration, multiple btf_tag's are allowed.
For detailed use cases, please see
https://lists.llvm.org/pipermail/llvm-dev/2021-June/151009.html
In case that there exist redeclarations, the btf_tag attributes
will be accumulated along with different declarations, and the
last declaration will contain all attributes.
Differential Revision: https://reviews.llvm.org/D106614
The diagnostic texts for warning on attributes that don't appear on the
initial declaration is generally useful. We'd like to re-use it in
D106030, but first let's combine two that already are very similar so we
may re-use it a third time in that commit.
Also, fix a few places that were using notePreviousDefinition to point
to declarations, to instead use diag::note_previous_declaration.
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D107613
This reverts commit 5181be344a.
Break libcxx type_traits header which uses aligned storage with
alignments greater than 4096. Reverting untill we can fix the header.
On AIX an aligned attribute cannot decrease the alignment of a variable
when placed on a variable declaration of vector type.
Differential Revision: https://reviews.llvm.org/D107522
Limit the maximum alignment for attribute aligned to 4096 to match
the limit of the .align pseudo op in the system assembler.
Differential Revision: https://reviews.llvm.org/D107497
We caught the cases where the user would explicitly use the & operator,
but we were missing implicit conversions such as array decay.
Fixes PR26336. Thanks to Samuel Neves for inspiration for the patch.
Clang implemented the _ExtInt datatype as a bit-precise integer type,
which was then proposed to WG14. WG14 has accepted the proposal
(http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2709.pdf), but Clang
requires some additional work as a result.
In the original Clang implementation, we elected to disallow implicit
conversions involving these types until after WG14 finalized the rules.
This patch implements the rules decided by WG14: no integer promotion
for bit-precise types, conversions prefer the larger of the two types
and in the event of a tie (say _ExtInt(32) and a 32-bit int), the
standard type wins.
There are more changes still needed to conform to N2709, but those will
be handled in follow-up patches.
Taking the address of a reference parameter might be valid, and without
CFA, false positives are going to be more trouble than they're worth.
Differential Revision: https://reviews.llvm.org/D102728
This commit adds supports for clang to remap macOS availability attributes that have introduced,
deprecated or obsoleted versions to appropriate Mac Catalyst availability attributes. This
mapping is done using the version mapping provided in the macOS SDK, in the SDKSettings.json file.
The mappings in the SDKSettings json file will also be used in the clang driver for the driver
Mac Catalyst patch, and they could also be used in the future for other platforms as well.
Differential Revision: https://reviews.llvm.org/D105257
This commit adds support for Mac Catalyst availability attribute, as
supported by the Apple clang compiler. A follow-up commit will provide
additional support for inferring Mac Catalyst availability from macOS
availability using the mapping in the SDKSettings.json.
Differential Revision: https://reviews.llvm.org/D105052
Summary:
Test and produce warning for subtracting a pointer from null or subtracting
null from a pointer.
This reland adds the functionality that the warning is no longer reusing an
existing warning, it has different wording for C vs C++ to refect the fact
that nullptr-nullptr has defined behaviour in C++, it is suppressed
when the warning is triggered by a system header and adds
-Wnull-pointer-subtraction to allow the warning to be controlled. -Wextra
implies -Wnull-pointer-subtraction.
Author: Jamie Schmeiser <schmeise@ca.ibm.com>
Reviewed By: efriedma (Eli Friedman), nickdesaulniers (Nick Desaulniers)
Differential Revision: https://reviews.llvm.org/D98798
The anonymous and non-anonymous bit-field diagnostics are easily
combined into one diagnostic. However, the diagnostic was missing a
"the" that is present in the almost-identically worded
warn_bitfield_width_exceeds_type_width diagnostic, hence the changes to
test cases.
This change is intended as initial setup. The plan is to add
more semantic checks later. I plan to update the documentation
as more semantic checks are added (instead of documenting the
details up front). Most of the code closely mirrors that for
the Swift calling convention. Three places are marked as
[FIXME: swiftasynccc]; those will be addressed once the
corresponding convention is introduced in LLVM.
Reviewed By: rjmccall
Differential Revision: https://reviews.llvm.org/D95561
This reverts commit 52aeacfbf5.
There isn't full agreement on a path forward yet, but there is agreement that
this shouldn't land as-is. See discussion on https://reviews.llvm.org/D105338
Also reverts unreviewed "[clang] Improve `-Wnull-dereference` diag to be more in-line with reality"
This reverts commit f4877c78c0.
And all the related changes to tests:
This reverts commit 9a0152799f.
This reverts commit 3f7c9cc274.
This reverts commit 329f8197ef.
This reverts commit aa9f58cc2c.
This reverts commit 2df37d5ddd.
This reverts commit a72a441812.
When there is unknown type in a struct in code compiled with
-Wcast-align, the compiler crashes due to
clang::ASTContext::getASTRecordLayout() failing an assert.
Added check that the RecordDecl is valid before calling
getASTRecordLayout().
A user reported an issue to me via email that Clang was accepting some
code that GCC was rejecting. After investigation, it turned out to be a
general problem of us failing to properly reject attributes written in
the type position in C when they don't apply to types. The root cause
was a terminology issue -- we sometimes use "CXX11Attr" to mean [[]] in
C++11 mode and sometimes [[]] in general -- and this came back to bite
us because in this particular case, it really meant [[]] in C++ mode.
I fixed the issue by introducing a new function
AttributeCommonInfo::isStandardAttributeSyntax() to represent [[]] in
either C or C++ mode.
This fix pointed out that we've had the issue in some of our existing
tests, which have all been corrected. This resolves
https://bugs.llvm.org/show_bug.cgi?id=50954.
This patch adds a new clang builtin, __arithmetic_fence. The purpose of the
builtin is to provide the user fine control, at the expression level, over
floating point optimization when -ffast-math (-ffp-model=fast) is enabled.
The builtin prevents the optimizer from rearranging floating point expression
evaluation. The new option fprotect-parens has the same effect on
parenthesized expressions, forcing the optimizer to respect the parentheses.
Reviewed By: aaron.ballman, kpn
Differential Revision: https://reviews.llvm.org/D100118
This patch adds a new clang builtin, __arithmetic_fence. The purpose of the
builtin is to provide the user fine control, at the expression level, over
floating point optimization when -ffast-math (-ffp-model=fast) is enabled.
The builtin prevents the optimizer from rearranging floating point expression
evaluation. The new option fprotect-parens has the same effect on
parenthesized expressions, forcing the optimizer to respect the parentheses.
Reviewed By: aaron.ballman, kpn
Differential Revision: https://reviews.llvm.org/D100118
Word on the grapevine was that the committee had some discussion that
ended with unanimous agreement on eliminating relational function pointer comparisons.
We wanted to be bold and just ban all of them cold turkey.
But then we chickened out at the last second and are going for
eliminating just the spaceship overload candidate instead, for now.
See D104680 for reference.
This should be fine and "safe", because the only possible semantic change this
would cause is that overload resolution could possibly be ambiguous if
there was another viable candidate equally as good.
But to save face a little we are going to:
* Issue an "error" for three-way comparisons on function pointers.
But all this is doing really is changing one vague error message,
from an "invalid operands to binary expression" into an
"ordered comparison of function pointers", which sounds more like we mean business.
* Otherwise "warn" that comparing function pointers like that is totally
not cool (unless we are told to keep quiet about this).
Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>
Reviewed By: rsmith
Differential Revision: https://reviews.llvm.org/D104892
According to https://eel.is/c++draft/over.literal
> double operator""_Bq(long double); // OK: does not use the reserved identifier _Bq ([lex.name])
> double operator"" _Bq(long double); // ill-formed, no diagnostic required: uses the reserved identifier _Bq ([lex.name])
Obey that rule by keeping track of the operator literal name status wrt. leading whitespace.
Fix: https://bugs.llvm.org/show_bug.cgi?id=50644
Differential Revision: https://reviews.llvm.org/D104299
GCC has had this function attribute since GCC 7.1 for this purpose. I
added "no_profile" last week in D104475; rename this to
"no_profile_instrument_function" to improve compatibility with GCC.
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80223#c11
Reviewed By: MaskRay, aaron.ballman
Differential Revision: https://reviews.llvm.org/D104658
Fixed crash when doing pointer math on a void pointer.
Also, reworked test to use -verify rather than FileCheck.
Reviewed By: erichkeane
Differential Revision: https://reviews.llvm.org/D104424
Check applied to unbounded (incomplete) arrays and pointers to spot
cases where the computed address is beyond the largest possible
addressable extent of the array, based on the address space in which the
array is delcared, or which the pointer refers to.
Check helps to avoid cases of nonsense pointer math and array indexing
which could lead to linker failures or runtime exceptions. Of
particular interest when building for embedded systems with small
address spaces.
This is version 2 of this patch -- version 1 had some testing issues
due to a sign error in existing code. That error is corrected and
lit test for this chagne is extended to verify the fix.
Originally reviewed/accepted by: aaron.ballman
Original revision: https://reviews.llvm.org/D86796
Reviewed By: aaron.ballman, ebevhan
Differential Revision: https://reviews.llvm.org/D88174
Yuanfang Chen