1483 Commits

Author SHA1 Message Date
Bill Wendling
fefdef808c
[Clang] Implement the 'counted_by' attribute (#76348)
The 'counted_by' attribute is used on flexible array members. The
argument for the attribute is the name of the field member holding the
count of elements in the flexible array. This information is used to
improve the results of the array bound sanitizer and the
'__builtin_dynamic_object_size' builtin. The 'count' field member must
be within the same non-anonymous, enclosing struct as the flexible array
member. For example:

```
  struct bar;
  struct foo {
    int count;
    struct inner {
      struct {
        int count; /* The 'count' referenced by 'counted_by' */
      };
      struct {
        /* ... */
        struct bar *array[] __attribute__((counted_by(count)));
      };
    } baz;
  };
```

This example specifies that the flexible array member 'array' has the
number of elements allocated for it in 'count':

```
  struct bar;
  struct foo {
    size_t count;
     /* ... */
    struct bar *array[] __attribute__((counted_by(count)));
  };
```

This establishes a relationship between 'array' and 'count';
specifically that 'p->array' must have *at least* 'p->count' number of
elements available. It's the user's responsibility to ensure that this
relationship is maintained throughout changes to the structure.

In the following, the allocated array erroneously has fewer elements
than what's specified by 'p->count'. This would result in an
out-of-bounds access not not being detected:

```
  struct foo *p;

  void foo_alloc(size_t count) {
    p = malloc(MAX(sizeof(struct foo),
                   offsetof(struct foo, array[0]) + count *
                       sizeof(struct bar *)));
    p->count = count + 42;
  }
```

The next example updates 'p->count', breaking the relationship
requirement that 'p->array' must have at least 'p->count' number of
elements available:

```
  void use_foo(int index, int val) {
    p->count += 42;
    p->array[index] = val; /* The sanitizer can't properly check this access */
  }
```

In this example, an update to 'p->count' maintains the relationship
requirement:

```
  void use_foo(int index, int val) {
    if (p->count == 0)
      return;
    --p->count;
    p->array[index] = val;
  }
```
2024-01-10 15:21:10 -08:00
Bill Wendling
cca4d6cfd2
Revert counted_by attribute feature (#75857)
There are many issues that popped up with the counted_by feature. The
patch #73730 has grown too large and approval is blocking Linux testing.

Includes reverts of:
commit 769bc11f684d ("[Clang] Implement the 'counted_by' attribute
(#68750)")
commit bc09ec696209 ("[CodeGen] Revamp counted_by calculations
(#70606)")
commit 1a09cfb2f35d ("[Clang] counted_by attr can apply only to C99
flexible array members (#72347)")
commit a76adfb992c6 ("[NFC][Clang] Refactor code to calculate flexible
array member size (#72790)")
commit d8447c78ab16 ("[Clang] Correct handling of negative and
out-of-bounds indices (#71877)")
Partial commit b31cd07de5b7 ("[Clang] Regenerate test checks (NFC)")

Closes #73168
Closes #75173
2023-12-18 15:16:09 -08:00
Kazu Hirata
f3dcc2351c
[clang] Use StringRef::{starts,ends}_with (NFC) (#75149)
This patch replaces uses of StringRef::{starts,ends}with with
StringRef::{starts,ends}_with for consistency with
std::{string,string_view}::{starts,ends}_with in C++20.

I'm planning to deprecate and eventually remove
StringRef::{starts,ends}with.
2023-12-13 08:54:13 -08:00
Eduard Zingerman
030b8cb156 [BPF] Attribute preserve_static_offset for structs
This commit adds a new BPF specific structure attribte
`__attribute__((preserve_static_offset))` and a pass to deal with it.

This attribute may be attached to a struct or union declaration, where
it notifies the compiler that this structure is a "context" structure.
The following limitations apply to context structures:
- runtime environment might patch access to the fields of this type by
  updating the field offset;

  BPF verifier limits access patterns allowed for certain data
  types. E.g. `struct __sk_buff` and `struct bpf_sock_ops`. For these
  types only `LD/ST <reg> <static-offset>` memory loads and stores are
  allowed.

  This is so because offsets of the fields of these structures do not
  match real offsets in the running kernel. During BPF program
  load/verification loads and stores to the fields of these types are
  rewritten so that offsets match real offsets. For this rewrite to
  happen static offsets have to be encoded in the instructions.

  See `kernel/bpf/verifier.c:convert_ctx_access` function in the Linux
  kernel source tree for details.

- runtime environment might disallow access to the field of the type
  through modified pointers.

  During BPF program verification a tag `PTR_TO_CTX` is tracked for
  register values. In case if register with such tag is modified BPF
  programs are not allowed to read or write memory using register. See
  kernel/bpf/verifier.c:check_mem_access function in the Linux kernel
  source tree for details.

Access to the structure fields is translated to IR as a sequence:
- `(load (getelementptr %ptr %offset))` or
- `(store (getelementptr %ptr %offset))`

During instruction selection phase such sequences are translated as a
single load instruction with embedded offset, e.g. `LDW %ptr, %offset`,
which matches access pattern necessary for the restricted
set of types described above (when `%offset` is static).

Multiple optimizer passes might separate these instructions, this
includes:
- SimplifyCFGPass (sinking)
- InstCombine (sinking)
- GVN (hoisting)

The `preserve_static_offset` attribute marks structures for which the
following transformations happen:
- at the early IR processing stage:
  - `(load (getelementptr ...))` replaced by call to intrinsic
    `llvm.bpf.getelementptr.and.load`;
  - `(store (getelementptr ...))` replaced by call to intrinsic
    `llvm.bpf.getelementptr.and.store`;
- at the late IR processing stage this modification is undone.

Such handling prevents various optimizer passes from generating
sequences of instructions that would be rejected by BPF verifier.

The __attribute__((preserve_static_offset)) has a priority over
__attribute__((preserve_access_index)). When preserve_access_index
attribute is present preserve access index transformations are not
applied.

This addresses the issue reported by the following thread:

https://lore.kernel.org/bpf/CAA-VZPmxh8o8EBcJ=m-DH4ytcxDFmo0JKsm1p1gf40kS0CE3NQ@mail.gmail.com/T/#m4b9ce2ce73b34f34172328f975235fc6f19841b6

This is a second attempt to commit this change, previous reverted
commit is: cb13e9286b6d4e384b5d4203e853d44e2eff0f0f.
The following items had been fixed:
- test case bpf-preserve-static-offset-bitfield.c now uses
  `-triple bpfel` to avoid different codegen for little/big endian
  targets.
- BPFPreserveStaticOffset.cpp:removePAICalls() modified to avoid
  use after free for `WorkList` elements `V`.

Differential Revision: https://reviews.llvm.org/D133361
2023-12-05 19:21:42 +02:00
Eduard Zingerman
2484469803 Revert "[BPF] Attribute preserve_static_offset for structs"
This reverts commit cb13e9286b6d4e384b5d4203e853d44e2eff0f0f.
Buildbot reports MSAN failures in tests added in this commit:
https://lab.llvm.org/buildbot/#/builders/5/builds/38806

Failing tests:
  LLVM :: CodeGen/BPF/preserve-static-offset/load-arr-pai.ll
  LLVM :: CodeGen/BPF/preserve-static-offset/load-ptr-pai.ll
  LLVM :: CodeGen/BPF/preserve-static-offset/load-struct-pai.ll
  LLVM :: CodeGen/BPF/preserve-static-offset/load-union-pai.ll
  LLVM :: CodeGen/BPF/preserve-static-offset/store-pai.ll
2023-11-30 22:29:45 +02:00
Eduard Zingerman
cb13e9286b [BPF] Attribute preserve_static_offset for structs
This commit adds a new BPF specific structure attribte
`__attribute__((preserve_static_offset))` and a pass to deal with it.

This attribute may be attached to a struct or union declaration, where
it notifies the compiler that this structure is a "context" structure.
The following limitations apply to context structures:
- runtime environment might patch access to the fields of this type by
  updating the field offset;

  BPF verifier limits access patterns allowed for certain data
  types. E.g. `struct __sk_buff` and `struct bpf_sock_ops`. For these
  types only `LD/ST <reg> <static-offset>` memory loads and stores are
  allowed.

  This is so because offsets of the fields of these structures do not
  match real offsets in the running kernel. During BPF program
  load/verification loads and stores to the fields of these types are
  rewritten so that offsets match real offsets. For this rewrite to
  happen static offsets have to be encoded in the instructions.

  See `kernel/bpf/verifier.c:convert_ctx_access` function in the Linux
  kernel source tree for details.

- runtime environment might disallow access to the field of the type
  through modified pointers.

  During BPF program verification a tag `PTR_TO_CTX` is tracked for
  register values. In case if register with such tag is modified BPF
  programs are not allowed to read or write memory using register. See
  kernel/bpf/verifier.c:check_mem_access function in the Linux kernel
  source tree for details.

Access to the structure fields is translated to IR as a sequence:
- `(load (getelementptr %ptr %offset))` or
- `(store (getelementptr %ptr %offset))`

During instruction selection phase such sequences are translated as a
single load instruction with embedded offset, e.g. `LDW %ptr, %offset`,
which matches access pattern necessary for the restricted
set of types described above (when `%offset` is static).

Multiple optimizer passes might separate these instructions, this
includes:
- SimplifyCFGPass (sinking)
- InstCombine (sinking)
- GVN (hoisting)

The `preserve_static_offset` attribute marks structures for which the
following transformations happen:
- at the early IR processing stage:
  - `(load (getelementptr ...))` replaced by call to intrinsic
    `llvm.bpf.getelementptr.and.load`;
  - `(store (getelementptr ...))` replaced by call to intrinsic
    `llvm.bpf.getelementptr.and.store`;
- at the late IR processing stage this modification is undone.

Such handling prevents various optimizer passes from generating
sequences of instructions that would be rejected by BPF verifier.

The __attribute__((preserve_static_offset)) has a priority over
__attribute__((preserve_access_index)). When preserve_access_index
attribute is present preserve access index transformations are not
applied.

This addresses the issue reported by the following thread:

https://lore.kernel.org/bpf/CAA-VZPmxh8o8EBcJ=m-DH4ytcxDFmo0JKsm1p1gf40kS0CE3NQ@mail.gmail.com/T/#m4b9ce2ce73b34f34172328f975235fc6f19841b6

Differential Revision: https://reviews.llvm.org/D133361
2023-11-30 19:45:03 +02:00
Chris B
2630d72cb3
[HLSL] Support vector swizzles on scalars (#67700)
HLSL supports vector swizzles on scalars by implicitly converting the
scalar to a single-element vector. This syntax is a convienent way to
initialize vectors based on filling a scalar value.

There are two parts of this change. The first part in the Lexer splits
numeric constant tokens when a `.x` or `.r` suffix is encountered. This
splitting is a bit hacky but allows the numeric constant to be parsed
separately from the vector element expression. There is an ambiguity
here with the `r` suffix used by fixed point types, however fixed point
types aren't supported in HLSL so this should not cause any exposable
problems (a separate issue has been filed to track validating language
options for HLSL: #67689).

The second part of this change is in Sema::LookupMemberExpr. For HLSL,
if the base type is a scalar, we implicit cast the scalar to a
one-element vector then call back to perform the vector lookup.

Fixes #56658 and #67511
2023-11-29 11:25:02 -06:00
Alex Voicu
57a0416e0e
[clang][CodeGen] Handle template parameter objects with explicit address spaces (#69266)
For certain cases (e.g. when their address is observable at run time) it
is necessary to provide physical backing for non-type template parameter
objects. Said backing comes in the form of a global variable. For
certain targets (e.g. AMDGPU), which use a non-default address space for
globals, this can lead to an issue when referencing said global in
address space agnostic languages (such as HIP), for example when passing
them to a function.

This patch addresses this issue by inserting an address space cast iff
there is an address space mismatch between the type of a reference
expression and the address space of the backing global. A test is also
added.
2023-11-29 00:15:18 +00:00
Bill Wendling
bc09ec6962
[CodeGen] Revamp counted_by calculations (#70606)
Break down the counted_by calculations so that they correctly handle
anonymous structs, which are specified internally as IndirectFieldDecls.

Improves the calculation of __bdos on a different field member in the struct.
And also improves support for __bdos in an index into the FAM. If the index
is further out than the length of the FAM, then we return __bdos's "can't
determine the size" value (zero or negative one, depending on type).

Also simplify the code to use helper methods to get the field referenced
by counted_by and the flexible array member itself, which also had some
issues with FAMs in sub-structs.
2023-11-09 10:18:17 -08:00
Vlad Serebrennikov
dda8e3de35 [clang][NFC] Refactor ImplicitParamDecl::ImplicitParamKind
This patch converts `ImplicitParamDecl::ImplicitParamKind` into a scoped enum at namespace scope, making it eligible for forward declaring. This is useful for `preferred_type` annotations on bit-fields.
2023-11-06 12:01:09 +03:00
Youngsuk Kim
14f2025671 [clang][CGExpr] Remove no-op ptr-to-ptr bitcasts (NFC)
Opaque ptr cleanup effort.
2023-11-02 17:50:46 -05:00
Bill Wendling
769bc11f68
[Clang] Implement the 'counted_by' attribute (#68750)
The 'counted_by' attribute is used on flexible array members. The
argument for the attribute is the name of the field member in the same
structure holding the count of elements in the flexible array. This
information can be used to improve the results of the array bound
sanitizer and the '__builtin_dynamic_object_size' builtin.

This example specifies the that the flexible array member 'array' has
the number of elements allocated for it in 'count':

  struct bar;
  struct foo {
    size_t count;
     /* ... */
    struct bar *array[] __attribute__((counted_by(count)));
  };

This establishes a relationship between 'array' and 'count',
specifically that 'p->array' must have *at least* 'p->count' number of
elements available. It's the user's responsibility to ensure that this
relationship is maintained through changes to the structure.

In the following, the allocated array erroneously has fewer elements
than what's specified by 'p->count'. This would result in an
out-of-bounds access not not being detected:

  struct foo *p;

  void foo_alloc(size_t count) {
    p = malloc(MAX(sizeof(struct foo),
                   offsetof(struct foo, array[0]) + count *
                       sizeof(struct bar *)));
    p->count = count + 42;
  }

The next example updates 'p->count', breaking the relationship
requirement that 'p->array' must have at least 'p->count' number of
elements available:

  struct foo *p;

  void foo_alloc(size_t count) {
    p = malloc(MAX(sizeof(struct foo),
                   offsetof(struct foo, array[0]) + count *
                       sizeof(struct bar *)));
    p->count = count + 42;
  }

  void use_foo(int index) {
    p->count += 42;
    p->array[index] = 0; /* The sanitizer cannot properly check this access */
  }

Reviewed By: nickdesaulniers, aaron.ballman

Differential Revision: https://reviews.llvm.org/D148381
2023-10-14 04:18:02 -07:00
alexfh
67b675ee55
Revert "[Clang] Implement the 'counted_by' attribute" (#68603)
This reverts commit 9a954c693573281407f6ee3f4eb1b16cc545033d, which
causes clang crashes when compiling with `-fsanitize=bounds`. See

9a954c6935 (commitcomment-129529574)
for details.
2023-10-09 20:53:48 +02:00
Bill Wendling
9a954c6935 [Clang] Implement the 'counted_by' attribute
The 'counted_by' attribute is used on flexible array members. The
argument for the attribute is the name of the field member in the same
structure holding the count of elements in the flexible array. This
information can be used to improve the results of the array bound sanitizer
and the '__builtin_dynamic_object_size' builtin.

This example specifies the that the flexible array member 'array' has the
number of elements allocated for it in 'count':

  struct bar;
  struct foo {
    size_t count;
     /* ... */
    struct bar *array[] __attribute__((counted_by(count)));
  };

This establishes a relationship between 'array' and 'count', specifically
that 'p->array' must have *at least* 'p->count' number of elements available.
It's the user's responsibility to ensure that this relationship is maintained
through changes to the structure.

In the following, the allocated array erroneously has fewer elements than
what's specified by 'p->count'. This would result in an out-of-bounds access not
not being detected:

  struct foo *p;

  void foo_alloc(size_t count) {
    p = malloc(MAX(sizeof(struct foo),
                   offsetof(struct foo, array[0]) + count *
                       sizeof(struct bar *)));
    p->count = count + 42;
  }

The next example updates 'p->count', breaking the relationship requirement that
'p->array' must have at least 'p->count' number of elements available:

  struct foo *p;

  void foo_alloc(size_t count) {
    p = malloc(MAX(sizeof(struct foo),
                   offsetof(struct foo, array[0]) + count *
                       sizeof(struct bar *)));
    p->count = count + 42;
  }

  void use_foo(int index) {
    p->count += 42;
    p->array[index] = 0; /* The sanitizer cannot properly check this access */
  }

Reviewed By: nickdesaulniers, aaron.ballman

Differential Revision: https://reviews.llvm.org/D148381
2023-10-04 18:26:15 -07:00
Corentin Jabot
af4751738d [C++] Implement "Deducing this" (P0847R7)
This patch implements P0847R7 (partially),
CWG2561 and CWG2653.

Reviewed By: aaron.ballman, #clang-language-wg

Differential Revision: https://reviews.llvm.org/D140828
2023-10-02 14:33:02 +02:00
Oskar Wirga
832b3b2462
Modify BoundsSan to improve debuggability (#65972)
Context
BoundsSanitizer is a mitigation that is part of UBSAN. It can be enabled
in "trap" mode to crash on OOB array accesses.

Problem
BoundsSan has zero false positives meaning every crash is a OOB array
access, unfortunately optimizations cause these crashes in production
builds to be a bit useless because we only know which function is
crashing but not which line of code.

Godbolt example of the optimization: https://godbolt.org/z/6qjax9z1b

This Diff
I wanted to provide a way to know exactly which LOC is responsible for
the crash. What we do here is use the size of the basic block as an
iterator to an immediate value for the ubsan trap.

Previous discussion: https://reviews.llvm.org/D148654
2023-09-29 15:34:31 -07:00
Björn Pettersson
b4858c634e
[clang][CodeGen] Simplify code based on opaque pointers (#65624)
- Update CodeGenTypeCache to use a single union for all pointers in
  address space zero.
- Introduce a UnqualPtrTy in CodeGenTypeCache, and use that (for
  example instead of llvm::PointerType::getUnqual) in some places.
- Drop some redundant bit/pointers casts from ptr to ptr.
2023-09-25 11:21:24 +02:00
Umesh Kalappa
2641d9b280 Propagate the volatile qualifier of exp to store /load operations .
This changes to address the PR : 55207

We update the volatility  on the LValue by looking at the LHS cast operation qualifier and propagate the RValue volatile-ness   from  the CGF data structure .

Reviewed By: rjmccall

Differential Revision: https://reviews.llvm.org/D157890
2023-09-23 19:40:24 +05:30
Yi Kong
3568976375 Reland^2 "Fix __cfi_check not aligned to 4k on relocatable files with no executable code"
This reverts commit 043d03d25bd7eadef66685de298342b35fe6b466.
2023-08-17 16:33:46 +09:00
Jonas Hahnfeld
2f3fe3ed97 [CodeGen] Remove Constant arguments from linkage functions, NFCI.
This was unused since commit dd2362a8ba last year.

Differential Revision: https://reviews.llvm.org/D156891
2023-08-17 08:28:51 +02:00
David Blaikie
19f2b68095 Make globals with mutable members non-constant, even in custom sections
Turned out we were making overly simple assumptions about which sections (& section flags) would be used when emitting a global into a custom section. This lead to sections with read-only flags being used for globals of struct types with mutable members.

Fixed by porting the codegen function with the more nuanced handling/checking for mutable members out of codegen for use in the sema code that does this initial checking/mapping to section flags.

Differential Revision: https://reviews.llvm.org/D156726
2023-08-14 22:25:42 +00:00
Florian Mayer
043d03d25b Revert "Reland "Fix __cfi_check not aligned to 4k on relocatable files with no executable code""
Broke sanitizer build bots

This reverts commit b82c2b9ac2baae0f2a9dd65770cfb37fdc2a80a9.
2023-08-04 14:24:26 -07:00
Yi Kong
b82c2b9ac2 Reland "Fix __cfi_check not aligned to 4k on relocatable files with no executable code"
This reverts commit a093598e50e7b252205f1164751ac9c74874e254.

Fixed test breakage.
2023-08-04 16:02:27 +09:00
Bjorn Pettersson
2bdc86484d [clang][CodeGen] Drop some typed pointer bitcasts
Differential Revision: https://reviews.llvm.org/D156911
2023-08-03 22:54:33 +02:00
Yi Kong
a093598e50 Revert "Fix __cfi_check not aligned to 4k on relocatable files with no executable code"
This reverts commit c7cacb2f6efe07fa4a1129bb7e2389312670b84a.

Broken tests.
2023-08-03 22:03:43 +09:00
Yi Kong
c7cacb2f6e Fix __cfi_check not aligned to 4k on relocatable files with no executable code
CrossDSOCFIPass is supposed to replace this stub function to a properly
aligned function. However the pass is not ran if the file has no
executable code, thus producing incorrectly aligned __cfi_check.

Fixes https://github.com/llvm/llvm-project/issues/45638.

Differential Revision: https://reviews.llvm.org/D155736
2023-08-03 19:53:54 +09:00
Corentin Jabot
8698262a43 [Clang] Fix consteval propagation for aggregates and defaulted constructors
This patch does a few things:

* Fix aggregate initialization.
  When an aggregate has an initializer that is immediate-escalating,
  the context in which it is used automatically becomes an immediate function.
  The wording does that by rpretending an aggregate initialization is itself
  an invocation which is not really how clang works, so my previous attempt
  was... wrong.

* Fix initialization of defaulted constructors with immediate escalating
  default member initializers.
  The wording was silent about that case and I did not handled it fully
  https://cplusplus.github.io/CWG/issues/2760.html

* Fix diagnostics
  In some cases clang would produce additional and unhelpful
  diagnostics by listing the invalid references to consteval
  function that appear in immediate escalating functions

Fixes https://github.com/llvm/llvm-project/issues/63742

Reviewed By: aaron.ballman, #clang-language-wg, Fznamznon

Differential Revision: https://reviews.llvm.org/D155175
2023-07-24 18:15:38 +02:00
Matt Arsenault
bac2a07540 clang: Attach !fpmath metadata to __builtin_sqrt based on language flags
OpenCL and HIP have -cl-fp32-correctly-rounded-divide-sqrt and
-fno-hip-correctly-rounded-divide-sqrt. The corresponding fpmath metadata
was only set on fdiv, and not sqrt. The backend is currently underutilizing
sqrt lowering options, and the responsibility is split between the libraries
and backend and this metadata is needed.

CUDA/NVCC has -prec-div and -prev-sqrt but clang doesn't appear to be
aiming for compatibility with those. Don't know if OpenMP has a similar
control.
2023-07-14 18:46:18 -04:00
Sergio Afonso
63ca93c7d1
[OpenMP][OMPIRBuilder] Rename IsEmbedded and IsTargetCodegen flags
This patch renames the `OpenMPIRBuilderConfig` flags to reduce confusion over
their meaning. `IsTargetCodegen` becomes `IsGPU`, whereas `IsEmbedded` becomes
`IsTargetDevice`. The `-fopenmp-is-device` compiler option is also renamed to
`-fopenmp-is-target-device` and the `omp.is_device` MLIR attribute is renamed
to `omp.is_target_device`. Getters and setters of all these renamed properties
are also updated accordingly. Many unit tests have been updated to use the new
names, but an alias for the `-fopenmp-is-device` option is created so that
external programs do not stop working after the name change.

`IsGPU` is set when the target triple is AMDGCN or NVIDIA PTX, and it is only
valid if `IsTargetDevice` is specified as well. `IsTargetDevice` is set by the
`-fopenmp-is-target-device` compiler frontend option, which is only added to
the OpenMP device invocation for offloading-enabled programs.

Differential Revision: https://reviews.llvm.org/D154591
2023-07-10 14:14:16 +01:00
Youngsuk Kim
6f986bffc5 [clang] Remove CGBuilderTy::CreateElementBitCast
`CGBuilderTy::CreateElementBitCast()` no longer does what its name suggests.

Remove remaining in-tree uses by one of the following methods.

* drop the call entirely
* fold it to an `Address` construction
* replace it with `Address::withElementType()`

This is a NFC cleanup effort.

Reviewed By: barannikov88, nikic, jrtc27

Differential Revision: https://reviews.llvm.org/D154285
2023-07-02 10:40:16 -04:00
Sergei Barannikov
2348902268 [clang][CodeGen] Remove no-op EmitCastToVoidPtr (NFC)
Reviewed By: JOE1994

Differential Revision: https://reviews.llvm.org/D153694
2023-06-29 20:29:38 +03:00
Youngsuk Kim
44e63ffe2b [clang] Replace uses of CGBuilderTy::CreateElementBitCast (NFC)
* Add `Address::withElementType()` as a replacement for
  `CGBuilderTy::CreateElementBitCast`.

* Partial progress towards replacing `CreateElementBitCast`, as it no
  longer does what its name suggests. Either replace its uses with
  `Address::withElementType()`, or remove them if no longer needed.

* Remove unused parameter 'Name' of `CreateElementBitCast`

Reviewed By: barannikov88, nikic

Differential Revision: https://reviews.llvm.org/D153196
2023-06-18 04:13:15 +03:00
Paulo Matos
55aeb23fe0 [clang][WebAssembly] Implement support for table types and builtins
This commit implements support for WebAssembly table types and
respective builtins. Table tables are WebAssembly objects to store
reference types. They have a large amount of semantic restrictions
including, but not limited to, only being allowed to be declared
at the top-level as static arrays of zero-length. Not being arguments
or result of functions, not being stored ot memory, etc.

This commit introduces the __attribute__((wasm_table)) to attach to
arrays of WebAssembly reference types. And the following builtins to
manage tables:

* ref   __builtin_wasm_table_get(table, idx)
* void  __builtin_wasm_table_set(table, idx, ref)
* uint  __builtin_wasm_table_size(table)
* uint  __builtin_wasm_table_grow(table, ref, uint)
* void  __builtin_wasm_table_fill(table, idx, ref, uint)
* void  __builtin_wasm_table_copy(table, table, uint, uint, uint)

This commit also enables reference-types feature at bleeding-edge.

This is joint work with Alex Bradbury (@asb).

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D139010
2023-06-10 15:53:13 +02:00
Kazu Hirata
46deb4092d [CodeGen] Use llvm::LLVMContext::MD_nontemporal (NFC) 2023-05-29 00:41:51 -07:00
Simon Tatham
20d6dee40d -fsanitize=function: fix alignment fault on Arm targets.
Function pointers are checked by loading a prefix structure from just
before the function's entry point. However, on Arm, the function
pointer is not always exactly equal to the address of the entry point,
because Thumb function pointers have the low bit set to tell the BX
instruction to enter them in Thumb state. So the generated code loads
from an odd address and suffers an alignment fault.

Fixed by clearing the low bit of the function pointer before
subtracting 8.

Differential Revision: https://reviews.llvm.org/D151308
2023-05-25 09:22:45 +01:00
Manna, Soumi
cc6a6c48d4 [NFC][Clang] Fix Coverity bug with dereference null return value in clang::CodeGen::CodeGenFunction::EmitOMPArraySectionExpr()
Reported by Coverity:

Inside  "CGExpr.cpp" file, in clang::CodeGen::CodeGenFunction::EmitOMPArraySectionExpr(clang::OMPArraySectionExpr const *, bool): Return value of function which returns null is dereferenced without checking.

    } else {
  	//returned_null: getAsConstantArrayType returns nullptr (checked 83 out of 95 times).
  	// var_assigned: Assigning: CAT = nullptr return value from getAsConstantArrayType.
      auto *CAT = C.getAsConstantArrayType(ArrayTy);
  	//identity_transfer: Member function call CAT->getSize() returns an offset off CAT (this).

     // Dereference null return value (NULL_RETURNS)
     //dereference: Dereferencing a pointer that might be nullptr CAT->getSize() when calling APInt.
     ConstLength = CAT->getSize();
    }

This patch adds an assert to resolve the bug.

Reviewed By: erichkeane

Differential Revision: https://reviews.llvm.org/D151137
2023-05-23 07:25:21 -07:00
Fangrui Song
279a4d0d67 -fsanitize=function: support C
With D148785, -fsanitize=function no longer uses C++ RTTI objects and therefore
can support C. The rationale for reporting errors is C11 6.5.2.2p9:

> If the function is defined with a type that is not compatible with the type (of the expression) pointed to by the expression that denotes the called function, the behavior is undefined.

The mangled types approach we use does not exactly match the C type
compatibility (see `f(callee1)` below).
This is probably fine as the rules are unlikely leveraged in practice. In
addition, the call is warned by -Wincompatible-function-pointer-types-strict.

```
void callee0(int (*a)[]) {}
void callee1(int (*a)[1]) {}
void f(void (*fp)(int (*)[])) { fp(0); }
int main() {
  int a[1];
  f(callee0);
  f(callee1); // compatible but flagged by -fsanitize=function, -fsanitize=kcfi, and -Wincompatible-function-pointer-types-strict
}
```

Skip indirect call sites of a function type without a prototype to avoid deal
with C11 6.5.2.2p6. -fsanitize=kcfi skips such calls as well.

Reviewed By: #sanitizers, vitalybuka

Differential Revision: https://reviews.llvm.org/D148827
2023-05-22 10:11:30 -07:00
Fangrui Song
46f366494f -fsanitize=function: use type hashes instead of RTTI objects
Currently we use RTTI objects to check type compatibility. To support non-unique
RTTI objects, commit 5745eccef54ddd3caca278d1d292a88b2281528b added a
`checkTypeInfoEquality` string matching to the runtime.
The scheme is inefficient.

```
_Z1fv:
  .long   846595819                    # jmp
  .long   .L__llvm_rtti_proxy-_Z3funv
  ...

main:
  ...
  # Load the second word (pointer to the RTTI object) and dereference it.
  movslq  4(%rsi), %rax
  movq    (%rax,%rsi), %rdx
  # Is it the desired typeinfo object?
  leaq    _ZTIFvvE(%rip), %rax
  # If not, call __ubsan_handle_function_type_mismatch_v1, which may recover if checkTypeInfoEquality allows
  cmpq    %rax, %rdx
  jne     .LBB1_2
  ...

.section        .data.rel.ro,"aw",@progbits
  .p2align        3, 0x0
.L__llvm_rtti_proxy:
  .quad   _ZTIFvvE
```

Let's replace the indirect `_ZTI` pointer with a type hash similar to
`-fsanitize=kcfi`.

```
_Z1fv:
  .long   3238382334
  .long   2772461324  # type hash

main:
  ...
  # Load the second word (callee type hash) and check whether it is expected
  cmpl    $-1522505972, -4(%rax)
  # If not, fail: call __ubsan_handle_function_type_mismatch
  jne     .LBB2_2
```

The RTTI object derives its name from `clang::MangleContext::mangleCXXRTTI`,
which uses `mangleType`. `mangleTypeName` uses `mangleType` as well. So the
type compatibility change is high-fidelity.

Since we no longer need RTTI pointers in
`__ubsan::__ubsan_handle_function_type_mismatch_v1`, let's switch it back to
version 0, the original signature before
e215996a2932ed7c472f4e94dc4345b30fd0c373 (2019).
`__ubsan::__ubsan_handle_function_type_mismatch_abort` is not
recoverable, so we can revert some changes from
e215996a2932ed7c472f4e94dc4345b30fd0c373.

Reviewed By: samitolvanen

Differential Revision: https://reviews.llvm.org/D148785
2023-05-20 08:24:20 -07:00
Fangrui Song
ad31a2dcad Change -fsanitize=function to place two words before the function entry
The current implementation of -fsanitize=function places two words (the prolog
signature and the RTTI proxy) at the function entry, which makes the feature
incompatible with Intel Indirect Branch Tracking (IBT) that needs an ENDBR instruction
at the function entry. To allow the combination, move the two words before the
function entry, similar to -fsanitize=kcfi.

Armv8.5 Branch Target Identification (BTI) has a similar requirement.

Note: for IBT and BTI, whether a function gets a marker instruction at the entry
generally cannot be assumed (it can be disabled by a function attribute or
stronger LTO optimizations).

It is extremely unlikely for two words preceding a function entry to be
inaccessible. One way to achieve this is by ensuring that a function is
aligned at a page boundary and making the preceding page unmapped or
unreadable. This is not reasonable for application or library code.
(Think: the first text section has crt* code not instrumented by
-fsanitize=function.)

We use 0xc105cafe for all targets. .long 0xc105cafe disassembles to invalid
instructions on all architectures I have tested, except Power where it is
`lfs 8, -13570(5)` (Load Floating-Point with a weird offset, unlikely to be used in real code).

---

For the removed function in AsmPrinter.cpp, remove an assert: `mdconst::extract`
already asserts non-nullness.

For compiler-rt/test/ubsan/TestCases/TypeCheck/Function/function.cpp,
when the function doesn't have prolog/epilog (-O1 and above), after moving the two words,
the address of the function equals the address of ret instruction,
so symbolizing the function will additionally get a non-zero column number.
Adjust the test to allow an optional column number.
```
  .long   3238382334
  .long   .L__llvm_rtti_proxy-_Z1fv
_Z1fv:   // symbolizing here retrieves the line table entry from the second .loc
  .file   0 ...
  .loc    0 1 0
  .cfi_startproc
  .loc    0 2 1 prologue_end
  retq
```

Reviewed By: peter.smith

Differential Revision: https://reviews.llvm.org/D148665
2023-05-19 07:50:29 -07:00
Hans Wennborg
7a85aa918c Emit const globals with constexpr destructor as constant LLVM values
This follows 2b4fa53 which made Clang not emit destructor calls for such
objects. However, they would still not get emitted as constants since
CodeGenModule::isTypeConstant() returns false if the destructor is
constexpr. This change adds a param to make isTypeConstant() ignore the
dtor, allowing the caller to check it instead.

Fixes Issue #61212

Differential revision: https://reviews.llvm.org/D145369
2023-03-16 11:02:27 +01:00
Wei Wang
ce7eb2e055 [Coroutines] Avoid creating conditional cleanup markers in suspend block
We shouldn't access coro frame after returning from `await_suspend()` and before `llvm.coro.suspend()`.
Make sure we always hoist conditional cleanup markers when inside the `await.suspend` block.

Fix https://github.com/llvm/llvm-project/issues/59181

Reviewed By: ChuanqiXu

Differential Revision: https://reviews.llvm.org/D144680
2023-02-28 15:30:04 -08:00
Akira Hatanaka
57865bc5ad [CodeGen] Add a flag to Address and Lvalue that is used to keep
track of whether the pointer is known not to be null

The flag will be used for the arm64e work we plan to upstream in the
future (see https://lists.llvm.org/pipermail/llvm-dev/2019-October/136091.html).
Currently the flag has no effect on code generation.

Differential Revision: https://reviews.llvm.org/D142584
2023-02-15 10:15:13 -08:00
Kazu Hirata
6ad0788c33 [clang] Use std::optional instead of llvm::Optional (NFC)
This patch replaces (llvm::|)Optional< with std::optional<.  I'll post
a separate patch to remove #include "llvm/ADT/Optional.h".

This is part of an effort to migrate from llvm::Optional to
std::optional:

https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716
2023-01-14 12:31:01 -08:00
Kazu Hirata
a1580d7b59 [clang] Add #include <optional> (NFC)
This patch adds #include <optional> to those files containing
llvm::Optional<...> or Optional<...>.

I'll post a separate patch to actually replace llvm::Optional with
std::optional.

This is part of an effort to migrate from llvm::Optional to
std::optional:

https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716
2023-01-14 11:07:21 -08:00
Guillaume Chatelet
bf5c17ed0f [clang][NFC] Remove dependency on DataLayout::getPrefTypeAlignment 2023-01-13 15:01:29 +00:00
Guillaume Chatelet
eaa1f46f11 [clang][NFC] Remove dependency on DataLayout::getPrefTypeAlignment 2023-01-13 13:19:19 +00:00
Nikita Popov
02856565ac [Clang] Emit noundef metadata next to range metadata
To preserve the previous semantics after D141386, adjust places
that currently emit !range metadata to also emit !noundef metadata.
This retains range violation as immediate undefined behavior,
rather than just poison.

Differential Revision: https://reviews.llvm.org/D141494
2023-01-12 10:03:05 +01:00
Guillaume Chatelet
6916ebd026 [clang][NFC] Use the TypeSize::getXXXValue() instead of TypeSize::getXXXSize)
This change is one of a series to implement the discussion from
https://reviews.llvm.org/D141134.
2023-01-11 16:07:48 +00:00
Yaxun (Sam) Liu
262c3034bb Revert "[AMDGPU] Disable bool range metadata to workaround backend issue"
This reverts commit 107ee2613063183cb643cef97f0fad403508c9f0 to facilitate
investigating and fixing the root cause.

Differential Revision: https://reviews.llvm.org/D135269
2022-12-08 17:35:10 -05:00
Kazu Hirata
bb666c6930 [CodeGen] Use std::nullopt instead of None (NFC)
This patch mechanically replaces None with std::nullopt where the
compiler would warn if None were deprecated.  The intent is to reduce
the amount of manual work required in migrating from Optional to
std::optional.

This is part of an effort to migrate from llvm::Optional to
std::optional:

https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716
2022-12-03 11:13:43 -08:00