Commit Graph

1079 Commits

Author SHA1 Message Date
Nick Desaulniers 140bfdca60 [clang][CodeGen] add fn_ret_thunk_extern to synthetic fns
Follow up fix to
commit 2240d72f15 ("[X86] initial -mfunction-return=thunk-extern
support")
https://reviews.llvm.org/D129572

@nathanchance reported that -mfunction-return=thunk-extern was failing
to annotate the asan and tsan contructors.
https://lore.kernel.org/llvm/Ys7pLq+tQk5xEa%2FB@dev-arch.thelio-3990X/

I then noticed the same occurring for gcov synthetic functions.

Similar to
commit 2786e67 ("[IR][sanitizer] Add module flag "frame-pointer" and set
it for cc1 -mframe-pointer={non-leaf,all}")
define a new module level MetaData, "fn_ret_thunk_extern", then when set
adds the fn_ret_thunk_extern IR Fn Attr to synthetically created
Functions.

Fixes https://github.com/llvm/llvm-project/issues/56514

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D129709
2022-07-14 11:25:24 -07:00
Mitch Phillips fd6dae9799 Update sanitize_* IR documentation.
sanitize_none was never actually committed, and should be removed.

no_sanitize_memtag is to be removed in D128950.

sanitize_memtag is new in D128950.

Also update the comments on other no_sanitize_* to indicate that they're
impacted by the sanitizer ignorelist and the global-disable attribute.

Reviewed By: eugenis

Differential Revision: https://reviews.llvm.org/D129410
2022-07-13 08:54:41 -07:00
Nick Desaulniers 2240d72f15 [X86] initial -mfunction-return=thunk-extern support
Adds support for:
* `-mfunction-return=<value>` command line flag, and
* `__attribute__((function_return("<value>")))` function attribute

Where the supported <value>s are:
* keep (disable)
* thunk-extern (enable)

thunk-extern enables clang to change ret instructions into jmps to an
external symbol named __x86_return_thunk, implemented as a new
MachineFunctionPass named "x86-return-thunks", keyed off the new IR
attribute fn_ret_thunk_extern.

The symbol __x86_return_thunk is expected to be provided by the runtime
the compiled code is linked against and is not defined by the compiler.
Enabling this option alone doesn't provide mitigations without
corresponding definitions of __x86_return_thunk!

This new MachineFunctionPass is very similar to "x86-lvi-ret".

The <value>s "thunk" and "thunk-inline" are currently unsupported. It's
not clear yet that they are necessary: whether the thunk pattern they
would emit is beneficial or used anywhere.

Should the <value>s "thunk" and "thunk-inline" become necessary,
x86-return-thunks could probably be merged into x86-retpoline-thunks
which has pre-existing machinery for emitting thunks (which could be
used to implement the <value> "thunk").

Has been found to build+boot with corresponding Linux
kernel patches. This helps the Linux kernel mitigate RETBLEED.
* CVE-2022-23816
* CVE-2022-28693
* CVE-2022-29901

See also:
* "RETBLEED: Arbitrary Speculative Code Execution with Return
Instructions."
* AMD SECURITY NOTICE AMD-SN-1037: AMD CPU Branch Type Confusion
* TECHNICAL GUIDANCE FOR MITIGATING BRANCH TYPE CONFUSION REVISION 1.0
  2022-07-12
* Return Stack Buffer Underflow / Return Stack Buffer Underflow /
  CVE-2022-29901, CVE-2022-28693 / INTEL-SA-00702

SystemZ may eventually want to support "thunk-extern" and "thunk"; both
options are used by the Linux kernel's CONFIG_EXPOLINE.

This functionality has been available in GCC since the 8.1 release, and
was backported to the 7.3 release.

Many thanks for folks that provided discrete review off list due to the
embargoed nature of this hardware vulnerability. Many Bothans died to
bring us this information.

Link: https://www.youtube.com/watch?v=IF6HbCKQHK8
Link: https://github.com/llvm/llvm-project/issues/54404
Link: https://gcc.gnu.org/legacy-ml/gcc-patches/2018-01/msg01197.html
Link: https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/advisory-guidance/return-stack-buffer-underflow.html
Link: https://arstechnica.com/information-technology/2022/07/intel-and-amd-cpus-vulnerable-to-a-new-speculative-execution-attack/?comments=1
Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ce114c866860aa9eae3f50974efc68241186ba60
Link: https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-00702.html
Link: https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-00707.html

Reviewed By: aaron.ballman, craig.topper

Differential Revision: https://reviews.llvm.org/D129572
2022-07-12 09:17:54 -07:00
Joseph Huber 41fba3c107 [Metadata] Add 'exclude' metadata to add the exclude flags on globals
This patchs adds a new metadata kind `exclude` which implies that the
global variable should be given the necessary flags during code
generation to not be included in the final executable. This is done
using the ``SHF_EXCLUDE`` flag on ELF for example. This should make it
easier to specify this flag on a variable without needing to explicitly
check the section name in the target backend.

Depends on D129053 D129052

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D129151
2022-07-07 12:20:40 -04:00
Joseph Huber ed801ad5e5 [Clang] Use metadata to make identifying embedded objects easier
Currently we use the `embedBufferInModule` function to store binary
strings containing device offloading data inside the host object to
create a fatbinary. In the case of LTO, we need to extract this object
from the LLVM-IR. This patch adds a metadata node for the embedded
objects containing the embedded pointers and the sections they were
stored at. This should create a cleaner interface for identifying these
values.

In the future it may be worthwhile to also encode an `ID` in the
metadata corresponding to the object's special section type if relevant.
This would allow us to extract the data from an object file and LLVM-IR
using the same ID.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D129033
2022-07-07 12:20:25 -04:00
Shilei Tian 1023ddaf77 [LLVM] Add the support for fmax and fmin in atomicrmw instruction
This patch adds the support for `fmax` and `fmin` operations in `atomicrmw`
instruction. For now (at least in this patch), the instruction will be expanded
to CAS loop. There are already a couple of targets supporting the feature. I'll
create another patch(es) to enable them accordingly.

Reviewed By: arsenm

Differential Revision: https://reviews.llvm.org/D127041
2022-07-06 10:57:53 -04:00
Chen Zheng 2c3784cff8 [SCEV] recognize llvm.annotation intrinsic
Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D127835
2022-07-03 21:02:50 -04:00
Yuanfang Chen 6e2b3cc6ca Fix sphinx docs build
Fix "Title underline too short."
2022-06-27 12:22:04 -07:00
Yuanfang Chen 6678f8e505 [ubsan] Using metadata instead of prologue data for function sanitizer
Information in the function `Prologue Data` is intentionally opaque.
When a function with `Prologue Data` is duplicated. The self (global
value) references inside `Prologue Data` is still pointing to the
original function. This may cause errors like `fatal error: error in backend: Cannot represent a difference across sections`.

This patch detaches the information from function `Prologue Data`
and attaches it to a function metadata node.

This and D116130 fix https://github.com/llvm/llvm-project/issues/49689.

Reviewed By: pcc

Differential Revision: https://reviews.llvm.org/D115844
2022-06-27 12:09:13 -07:00
Bradley Smith a83aa33d1b [IR] Move vector.insert/vector.extract out of experimental namespace
These intrinsics are now fundemental for SVE code generation and have been
present for a year and a half, hence move them out of the experimental
namespace.

Differential Revision: https://reviews.llvm.org/D127976
2022-06-27 10:48:45 +00:00
Mitch Phillips 35b1a64589 Add documentation of new sanitizer-specific GV attributes.
Reviewed By: vitalybuka

Differential Revision: https://reviews.llvm.org/D126922
2022-06-10 12:46:02 -07:00
Guillaume Chatelet 38637ee477 [clang] Add support for __builtin_memset_inline
In the same spirit as D73543 and in reply to https://reviews.llvm.org/D126768#3549920 this patch is adding support for `__builtin_memset_inline`.

The idea is to get support from the compiler to easily write efficient memory function implementations.

This patch could be split in two:
 - one for the LLVM part adding the `llvm.memset.inline.*` intrinsics.
 - and another one for the Clang part providing the instrinsic as a builtin.

Differential Revision: https://reviews.llvm.org/D126903
2022-06-10 13:13:59 +00:00
Shilei Tian 0c3e6e5717 [NFC] Remove trailing whitespace 2022-06-06 18:59:13 -04:00
Guillaume Chatelet 53efdf33f8
Fix llvm.memset semantics description
The description was referring to a ``src`` parameter probably copied over from ``llvm.memcpy``
2022-06-02 13:25:03 +02:00
Martin Storsjö 668bb96379 [ARM] Implement lowering of the sponentry intrinsic
This is needed for SEH based setjmp on Windows.

Differential Revision: https://reviews.llvm.org/D126763
2022-06-02 12:29:59 +03:00
Augie Fackler b0a1a308f2 LangRef: fix bad indentation in allockind bullets 2022-05-31 11:06:43 -04:00
Augie Fackler 42861faa8e attributes: introduce allockind attr for describing allocator fn behavior
I chose to encode the allockind information in a string constant because
otherwise we would get a bit of an explosion of keywords to deal with
the possible permutations of allocation function types.

I'm not sure that CodeGen.h is the correct place for this enum, but it
seemed to kind of match the UWTableKind enum so I put it in the same
place. Constructive suggestions on a better location most certainly
encouraged.

Differential Revision: https://reviews.llvm.org/D123088
2022-05-31 10:01:17 -04:00
Lian Wang 967ef4ad0a [NFC][VP] Fix llvm.vp.merge intrinsic Expansion in LangRef
Reviewed By: simoll

Differential Revision: https://reviews.llvm.org/D126457
2022-05-30 01:43:41 +00:00
Sebastian Peryt d1c5da34a7 [DOC] Improve LangRef description of declare
This patch fixes formatting inside Functions section of declare
by making it consistent with the way how define is written.

Fixes #39844

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D125581
2022-05-26 14:34:34 -07:00
Sebastian Peryt 0f64945352 [DOC] Refactor Functions section in LangRef
This change is a small refactor of Functions section
to update placement of define syntax.

Reviewed By: RKSimon

Differential revision: https://reviews.llvm.org/D125831
2022-05-26 14:34:34 -07:00
Takafumi Arakaki 18e6b8234a Allow pointer types for atomicrmw xchg
This adds support for pointer types for `atomic xchg` and let us write
instructions such as `atomicrmw xchg i64** %0, i64* %1 seq_cst`. This
is similar to the patch for allowing atomicrmw xchg on floating point
types: https://reviews.llvm.org/D52416.

Differential Revision: https://reviews.llvm.org/D124728
2022-05-25 16:20:26 +00:00
Nuno Lopes 5a8e755101
[docs][LangRef] Fix typo in llvm.smul.fix example 2022-05-17 21:36:36 +01:00
David Kreitzer 29f70e3e7d Minor correction in bitreverse intrinsic semantics
Differential Revision: https://reviews.llvm.org/D124861
2022-05-03 11:41:10 -07:00
Serge Pavlov d9b5544e0f [Doc] Refine description of llvm.is_fpclass 2022-05-03 19:28:47 +07:00
Augie Fackler c7ae423e39 BuildLibCalls: add alloc-family attribute to many allocator functions
Differential Revision: https://reviews.llvm.org/D123086
2022-05-02 11:12:55 -04:00
Phoebe Wang 7c04454227 [ArgPromotion][Attributor] Update min-legal-vector-width when do promotion
X86 codegen uses function attribute `min-legal-vector-width` to select the proper ABI. The intention of the attribute is to reflect user's requirement when they passing or returning vector arguments. So Clang front-end will iterate the vector arguments and set `min-legal-vector-width` to the width of the maximum for both caller and callee.

It is assumed any middle end optimizations won't care of the attribute expect inlining and argument promotion.
- For inlining, we will propagate the attribute of inlined functions because the inlining functions become the newer caller.
- For argument promotion, we check the `min-legal-vector-width` of the caller and callee and refuse to promote when they don't match.

The problem comes from the optimizations' combination, as shown by https://godbolt.org/z/zo3hba8xW. The caller `foo` has two callees `bar` and `baz`. When doing argument promotion, both `foo` and `bar` has the same `min-legal-vector-width`. So the argument was promoted to vector. Then the inlining inlines `baz` to `foo` and updates `min-legal-vector-width`, which results in ABI mismatch between `foo` and `bar`.

This patch fixes the problem by expanding the concept of `min-legal-vector-width` to indicator of functions arguments. That says, any passes touch functions arguments have to set `min-legal-vector-width` to the value reflects the width of vector arguments. It makes sense to me because any arguments modifications are ABI related and should response for the ABI compatibility.

Differential Revision: https://reviews.llvm.org/D123284
2022-05-02 14:13:05 +08:00
David Tenty 8042699a30 [LLVM] Add exported visibility style for XCOFF
For the AIX linker, under default options, global or weak symbols which
have no visibility bits set to zero (i.e. no visibility, similar to ELF
default) are only exported if specified on an export list provided to
the linker. So AIX has an additional visibility style called
"exported" which indicates to the linker that the symbol should
be explicitly globally exported.

This change maps "dllexport" in the LLVM IR to correspond to XCOFF
exported as we feel this best models the intended semantic (discussion
on the discourse RFC thread: https://discourse.llvm.org/t/rfc-adding-exported-visibility-style-to-the-ir-to-model-xcoff-exported-visibility/61853)
and allows us to enable writing this visibility for the AIX target
in the assembly path.

Reviewed By: DiggerLin

Differential Revision: https://reviews.llvm.org/D123951
2022-04-28 14:56:00 -04:00
Augie Fackler a907d36cfe Attributes: add a new `allocptr` attribute
This continues the push away from hard-coded knowledge about functions
towards attributes. We'll use this to annotate free(), realloc() and
cousins and obviate the hard-coded list of free functions.

Differential Revision: https://reviews.llvm.org/D123083
2022-04-26 13:57:11 -04:00
Serge Pavlov 170a903144 Intrinsic for checking floating point class
This change introduces a new intrinsic, `llvm.is.fpclass`, which checks
if the provided floating-point number belongs to any of the the specified
value classes. The intrinsic implements the checks made by C standard
library functions `isnan`, `isinf`, `isfinite`, `isnormal`, `issubnormal`,
`issignaling` and corresponding IEEE-754 operations.

The primary motivation for this intrinsic is the support of strict FP
mode. In this mode using compare instructions or other FP operations is
not possible, because if the value is a signaling NaN, floating-point
exception `Invalid` is raised, but the aforementioned functions must
never raise exceptions.

Currently there are two solutions for this problem, both are
implemented partially. One of them is using integer operations to
implement the check. It was implemented in https://reviews.llvm.org/D95948
for `isnan`. It solves the problem of exceptions, but offers one
solution for all targets, although some can do the check in more
efficient way.

The other, implemented in https://reviews.llvm.org/D96568, introduced a
hook 'clang::TargetCodeGenInfo::testFPKind', which injects a target
specific code into IR to implement `isnan` and some other functions. It is
convenient for targets that have dedicated instruction to determine FP data
class. However using target-specific intrinsic complicates analysis and can
prevent some optimizations.

A special intrinsic for value class checks allows representing data class
tests with enough flexibility. During IR transformations it represents the
check in target-independent way and saves it from undesired transformations.
In the instruction selector it allows efficient lowering depending on the
used target and mode.

This implementation is an extended variant of `llvm.isnan` introduced
in https://reviews.llvm.org/D104854. It is limited to minimal intrinsic
support. Target-specific treatment will be implemented in separate
patches.

Differential Revision: https://reviews.llvm.org/D112025
2022-04-26 13:09:16 +07:00
Florian Hahn b00fd35277
[LangRef] Limit readnone,read/writeonly to memory visible outside the fn
This patch unifies the wording used for readnone, readonly and writeonly
attributes. The definitions now more specifically refer to memory visible
outside the function

The motivation for the clarification is D123473.

Reviewed By: nlopes

Differential Revision: https://reviews.llvm.org/D124124
2022-04-25 11:32:50 +01:00
Vitaly Buka 9be90748f1 Revert "[asan] Emit .size directive for global object size before redzone"
Revert "[docs] Fix underline"

Breaks a lot of asan tests in google.

This reverts commit 365c3e85bc.
This reverts commit 78a784bea4.
2022-04-21 16:21:17 -07:00
Alex Brachet 365c3e85bc [docs] Fix underline 2022-04-21 21:05:49 +00:00
Alex Brachet 78a784bea4 [asan] Emit .size directive for global object size before redzone
This emits an `st_size` that represents the actual useable size of an object before the redzone is added.

Reviewed By: vitalybuka, MaskRay, hctim

Differential Revision: https://reviews.llvm.org/D123010
2022-04-21 20:46:38 +00:00
Jonas Paulsson 46f83caebc [InlineAsm] Add support for address operands ("p").
This patch adds support for inline assembly address operands using the "p"
constraint on X86 and SystemZ.

This was in fact broken on X86 (see example at
https://reviews.llvm.org/D110267, Nov 23).

These operands should probably be treated the same as memory operands by
CodeGenPrepare, which have been commented with "TODO" there.

Review: Xiang Zhang and Ulrich Weigand

Differential Revision: https://reviews.llvm.org/D122220
2022-04-13 12:50:21 +02:00
Xiang1 Zhang a56f264958 Refine tls-load-hoista llvm option
Reviewed By: LuoYuanke

Differential Revision: https://reviews.llvm.org/D122890
2022-04-01 19:03:58 +08:00
yanming a7c0b7504c [VP] Add more cast VPintrinsic and docs.
Add vp.fptoui, vp.uitofp, vp.fptrunc, vp.fpext, vp.trunc, vp.zext, vp.sext, vp.ptrtoint, vp.inttoptr intrinsic and docs.

Reviewed By: frasercrmck, craig.topper

Differential Revision: https://reviews.llvm.org/D122291
2022-04-01 09:16:10 +08:00
Fraser Cormack cc67a8fcf1 [VP][LangRef] Correct select operands in vp.fptosi docs 2022-03-31 08:30:18 +01:00
Fraser Cormack 73244e8f85 [VP] Add vp.icmp comparison intrinsic and docs
This patch mostly follows up on D121292 which introduced the vp.fcmp
intrinsic.

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D122729
2022-03-30 17:05:11 +01:00
Fraser Cormack a0e5d9e1f4 [LangRef][NFC] Correct select operands in vp.fcmp docs
Thanks for craig.topper for spotting this.
2022-03-30 17:03:15 +01:00
Fraser Cormack da6131f20a [VP] Add vp.fcmp comparison intrinsic and docs
This patch adds the first support for vector-predicated comparison
intrinsics, starting with vp.fcmp. It uses metadata to encode its
condition code, like the llvm.experimental.constrained.fcmp intrinsic.

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D121292
2022-03-30 14:39:18 +01:00
Michael Kruse 793b7f903d [docs] Update LoopTerminology.
Includes 2 corrections:

 * Update irreducible control flow and add references to CycleTerminology;
   Natural loop is not the only definition of something looping in LLVM anymore.

 * Mention mustprogress loop and function attributes to be used
   instead of the llvm.sideeffect intrinsic.
2022-03-29 23:26:18 -05:00
Xiang1 Zhang 9566405020 [Inline asm] Fix mangle problem when variable used in inline asm.
(Correct 'Mem symbol + IntelExpr' output in PIC model)

Reviewed By: skan

Differential Revision: https://reviews.llvm.org/D121785
2022-03-24 09:41:23 +08:00
Nikita Popov 5737ce259b [LangRef] Allow non-power-of-two assume operand bundle
There has been a lot of confusion on this in the past (see for
example https://reviews.llvm.org/D110634 and earlier revisions),
so let's try to get some clarity here. This patch specifies that
a) specifying a non-constant assumed alignment is explicitly
allowed and b) an invalid (non-power-of-two) alignment is not UB,
but rather converts it into an assumption that the pointer is null.

This change is done for two reasons:
a) Assume operand bundles are specifically used in cases where the
alignment is not known during frontend codegen (otherwise we'd just
use an align attribute), so rejecting this case doesn't make sense.
b) At least for aligned_alloc the C standard specifies that passing
an invalid alignment results in a null pointer, not undefined
behavior.

Differential Revision: https://reviews.llvm.org/D119414
2022-03-23 15:51:16 +01:00
Itay Bookstein d155c7da51 [docs] Fix a couple of typos
Signed-off-by: Itay Bookstein <ibookstein@gmail.com>
2022-03-19 20:24:38 +02:00
Fangrui Song c6692f819e [GlobalOpt] Don't replace alias with aliasee if either alias/aliasee may be preemptible
Generalize D99629 for ELF. A default visibility non-local symbol is preemptible
in a -shared link. `isInterposable` is an insufficient condition.

Moreover, a non-preemptible alias may be referenced in a sub constant expression
which intends to lower to a PC-relative relocation. Replacing the alias with a
preemptible aliasee may introduce a linker error.

Respect dso_preemptable and suppress optimization to fix the abose issues. With
the change, `alias = 345` will not be rewritten to use aliasee in a `-fpic`
compile.
```
int aliasee;
extern int alias __attribute__((alias("aliasee"), visibility("hidden")));
void foo() { alias = 345; } // intended to access the local copy
```

While here, refine the condition for the alias as well.

For some binary formats like COFF, `isInterposable` is a sufficient condition.
But I think canonicalization for the changed case has little advantage, so I
don't bother to add the `Triple(M.getTargetTriple()).isOSBinFormatELF()` or
`getPICLevel/getPIELevel` complexity.

For instrumentations, it's recommended not to create aliases that refer to
globals that have a weak linkage or is preemptible. However, the following is
supported and the IR needs to handle such cases.
```
int aliasee __attribute__((weak));
extern int alias __attribute__((alias("aliasee")));
```

There are other places where GlobalAlias isInterposable usage may need to be
fixed.

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D107249
2022-03-18 14:17:05 -07:00
Lorenzo Albano 28cfa764c2 [VP] Strided loads/stores
This patch introduces two new experimental IR intrinsics and SDAG nodes
to represent vector strided loads and stores.

Reviewed By: simoll

Differential Revision: https://reviews.llvm.org/D114884
2022-03-10 18:46:54 +01:00
Xiang1 Zhang c31014322c TLS loads opimization (hoist)
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D120000
2022-03-10 09:29:06 +08:00
Augie Fackler d664c4b73c Attributes: add a new allocalign attribute
This will let us start moving away from hard-coded attributes in
MemoryBuiltins.cpp and put the knowledge about various attribute
functions in the compilers that emit those calls where it probably
belongs.

Differential Revision: https://reviews.llvm.org/D117921
2022-03-04 15:57:53 -05:00
Arthur Eubanks f0b61f7957 Revert "[GlobalOpt] Don't replace alias with aliasee if either alias/aliasee may be preemptible"
This reverts commit 30e8f83c84.

Causes huge compile time regressions on certain large files. Will followup offline with author.
2022-03-03 11:04:14 -08:00
Simon Moll d05ddb86f6 [VP] vp.sitofp cast intrinsic and docs
Reviewed By: frasercrmck

Differential Revision: https://reviews.llvm.org/D119922
2022-03-02 10:16:19 +01:00