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
This patch fixes crashes related with how PatchableFunction selects the instruction to make patchable:
- Ensure PatchableFunction skips all instructions that don't generate actual machine instructions.
- Handle the case where the first MachineBasicBlock is empty
- Removed support for 16 bit x86 architectures.
Note: another issue remains related with PatchableFunction, in the lowering part.
See https://github.com/llvm/llvm-project/issues/59039
Differential Revision: https://reviews.llvm.org/D137642
This patch makes code less readable but it will clean itself after all functions are converted.
Differential Revision: https://reviews.llvm.org/D138665
When the Linux kernel is compiled without -mretpoline, KCFI fails
ungracefully because it doesn't handle indirect calls with a memory
target operand. Since the KCFI check will need to load the target
address into a register for validating the type hash anyway, simply
unfold memory operands in indirect calls that need a KCFI check.
Fixes#59017
The KCFI sanitizer, enabled with `-fsanitize=kcfi`, implements a
forward-edge control flow integrity scheme for indirect calls. It
uses a !kcfi_type metadata node to attach a type identifier for each
function and injects verification code before indirect calls.
Unlike the current CFI schemes implemented in LLVM, KCFI does not
require LTO, does not alter function references to point to a jump
table, and never breaks function address equality. KCFI is intended
to be used in low-level code, such as operating system kernels,
where the existing schemes can cause undue complications because
of the aforementioned properties. However, unlike the existing
schemes, KCFI is limited to validating only function pointers and is
not compatible with executable-only memory.
KCFI does not provide runtime support, but always traps when a
type mismatch is encountered. Users of the scheme are expected
to handle the trap. With `-fsanitize=kcfi`, Clang emits a `kcfi`
operand bundle to indirect calls, and LLVM lowers this to a
known architecture-specific sequence of instructions for each
callsite to make runtime patching easier for users who require this
functionality.
A KCFI type identifier is a 32-bit constant produced by taking the
lower half of xxHash64 from a C++ mangled typename. If a program
contains indirect calls to assembly functions, they must be
manually annotated with the expected type identifiers to prevent
errors. To make this easier, Clang generates a weak SHN_ABS
`__kcfi_typeid_<function>` symbol for each address-taken function
declaration, which can be used to annotate functions in assembly
as long as at least one C translation unit linked into the program
takes the function address. For example on AArch64, we might have
the following code:
```
.c:
int f(void);
int (*p)(void) = f;
p();
.s:
.4byte __kcfi_typeid_f
.global f
f:
...
```
Note that X86 uses a different preamble format for compatibility
with Linux kernel tooling. See the comments in
`X86AsmPrinter::emitKCFITypeId` for details.
As users of KCFI may need to locate trap locations for binary
validation and error handling, LLVM can additionally emit the
locations of traps to a `.kcfi_traps` section.
Similarly to other sanitizers, KCFI checking can be disabled for a
function with a `no_sanitize("kcfi")` function attribute.
Relands 67504c9549 with a fix for
32-bit builds.
Reviewed By: nickdesaulniers, kees, joaomoreira, MaskRay
Differential Revision: https://reviews.llvm.org/D119296
The KCFI sanitizer, enabled with `-fsanitize=kcfi`, implements a
forward-edge control flow integrity scheme for indirect calls. It
uses a !kcfi_type metadata node to attach a type identifier for each
function and injects verification code before indirect calls.
Unlike the current CFI schemes implemented in LLVM, KCFI does not
require LTO, does not alter function references to point to a jump
table, and never breaks function address equality. KCFI is intended
to be used in low-level code, such as operating system kernels,
where the existing schemes can cause undue complications because
of the aforementioned properties. However, unlike the existing
schemes, KCFI is limited to validating only function pointers and is
not compatible with executable-only memory.
KCFI does not provide runtime support, but always traps when a
type mismatch is encountered. Users of the scheme are expected
to handle the trap. With `-fsanitize=kcfi`, Clang emits a `kcfi`
operand bundle to indirect calls, and LLVM lowers this to a
known architecture-specific sequence of instructions for each
callsite to make runtime patching easier for users who require this
functionality.
A KCFI type identifier is a 32-bit constant produced by taking the
lower half of xxHash64 from a C++ mangled typename. If a program
contains indirect calls to assembly functions, they must be
manually annotated with the expected type identifiers to prevent
errors. To make this easier, Clang generates a weak SHN_ABS
`__kcfi_typeid_<function>` symbol for each address-taken function
declaration, which can be used to annotate functions in assembly
as long as at least one C translation unit linked into the program
takes the function address. For example on AArch64, we might have
the following code:
```
.c:
int f(void);
int (*p)(void) = f;
p();
.s:
.4byte __kcfi_typeid_f
.global f
f:
...
```
Note that X86 uses a different preamble format for compatibility
with Linux kernel tooling. See the comments in
`X86AsmPrinter::emitKCFITypeId` for details.
As users of KCFI may need to locate trap locations for binary
validation and error handling, LLVM can additionally emit the
locations of traps to a `.kcfi_traps` section.
Similarly to other sanitizers, KCFI checking can be disabled for a
function with a `no_sanitize("kcfi")` function attribute.
Reviewed By: nickdesaulniers, kees, joaomoreira, MaskRay
Differential Revision: https://reviews.llvm.org/D119296
`BMI` new instruction `tzcnt` has better performance than `bsf` on new
processors. Its encoding has a mandatory prefix '0xf3' compared to
`bsf`. If we force emit `rep` prefix for `bsf`, we will gain better
performance when the same code run on new processors.
GCC has already done this way: https://c.godbolt.org/z/6xere6fs1Fixes#34191
Reviewed By: craig.topper, skan
Differential Revision: https://reviews.llvm.org/D130956
`BMI` new instruction `tzcnt` has better performance than `bsf` on new
processors. Its encoding has a mandatory prefix '0xf3' compared to
`bsf`. If we force emit `rep` prefix for `bsf`, we will gain better
performance when the same code run on new processors.
GCC has already done this way: https://c.godbolt.org/z/6xere6fs1Fixes#34191
Reviewed By: skan
Differential Revision: https://reviews.llvm.org/D130956
D25618 added a method to verify the instruction predicates for an
emitted instruction, through verifyInstructionPredicates added into
<Target>MCCodeEmitter::encodeInstruction. This is a very useful idea,
but the implementation inside MCCodeEmitter made it only fire for object
files, not assembly which most of the llvm test suite uses.
This patch moves the code into the <Target>_MC::verifyInstructionPredicates
method, inside the InstrInfo. The allows it to be called from other
places, such as in this patch where it is called from the
<Target>AsmPrinter::emitInstruction methods which should trigger for
both assembly and object files. It can also be called from other places
such as verifyInstruction, but that is not done here (it tends to catch
errors earlier, but in reality just shows all the mir tests that have
incorrect feature predicates). The interface was also simplified
slightly, moving computeAvailableFeatures into the function so that it
does not need to be called externally.
The ARM, AMDGPU (but not R600), AVR, Mips and X86 backends all currently
show errors in the test-suite, so have been disabled with FIXME
comments.
Recommitted with some fixes for the leftover MCII variables in release
builds.
Differential Revision: https://reviews.llvm.org/D129506
This reverts commit e2fb8c0f4b as it does
not build for Release builds, and some buildbots are giving more warning
than I saw locally. Reverting to fix those issues.
D25618 added a method to verify the instruction predicates for an
emitted instruction, through verifyInstructionPredicates added into
<Target>MCCodeEmitter::encodeInstruction. This is a very useful idea,
but the implementation inside MCCodeEmitter made it only fire for object
files, not assembly which most of the llvm test suite uses.
This patch moves the code into the <Target>_MC::verifyInstructionPredicates
method, inside the InstrInfo. The allows it to be called from other
places, such as in this patch where it is called from the
<Target>AsmPrinter::emitInstruction methods which should trigger for
both assembly and object files. It can also be called from other places
such as verifyInstruction, but that is not done here (it tends to catch
errors earlier, but in reality just shows all the mir tests that have
incorrect feature predicates). The interface was also simplified
slightly, moving computeAvailableFeatures into the function so that it
does not need to be called externally.
The ARM, AMDGPU (but not R600), AVR, Mips and X86 backends all currently
show errors in the test-suite, so have been disabled with FIXME
comments.
Differential Revision: https://reviews.llvm.org/D129506
This reverts the functional changes of D103427 but keeps its tests, and
and reimplements the functionality by reusing the existing 32-bit
MASKMOVDQU and VMASKMOVDQU instructions as suggested by skan in review.
These instructions were previously predicated on Not64BitMode. This
reimplementation restores the disassembly of a class of instructions,
which will see a test added in followup patch D122449.
These instructions are in 64-bit mode special cased in
X86MCInstLower::Lower, because we use flags with one meaning for subtly
different things: we have an AdSize32 class which indicates both that
the instruction needs a 0x67 prefix and that the text form of the
instruction implies a 0x67 prefix. These instructions are special in
needing a 0x67 prefix but having a text form that does *not* imply a
0x67 prefix, so we encode this in MCInst as an instruction that has an
explicit address size override.
Note that originally VMASKMOVDQU64 was special cased to be excluded from
disassembly, as we cannot distinguish between VMASKMOVDQU and
VMASKMOVDQU64 and rely on the fact that these are indistinguishable, or
close enough to it, at the MCInst level that it does not matter which we
use. Because VMASKMOVDQU now receives special casing, even though it
does not make a difference in the current implementation, as a
precaution VMASKMOVDQU is excluded from disassembly rather than
VMASKMOVDQU64.
Reviewed By: RKSimon, skan
Differential Revision: https://reviews.llvm.org/D122540
When references to the symbol `swift_async_extendedFramePointerFlags`
are emitted they have to be weak.
References to the symbol `swift_async_extendedFramePointerFlags` get
emitted only by frame lowering code. Therefore, the backend needs to track
references to the symbol and mark them weak.
Differential Revision: https://reviews.llvm.org/D115672
This change moves optimized callbacks from each .o file to compiler-rt.
Reviewed By: vitalybuka, morehouse
Differential Revision: https://reviews.llvm.org/D115396
This change moves optimized callbacks from each .o file to compiler-rt.
Reviewed By: vitalybuka, morehouse
Differential Revision: https://reviews.llvm.org/D115396
Changed registers to R10 and R11 because PLT resolution clobbers them. Also changed the implementation to use R11 instead of RCX, which saves a push/pop.
Reviewed By: vitalybuka
Differential Revision: https://reviews.llvm.org/D115002
For tagged-globals, we only need to disable relaxation for globals that
we actually tag. With this patch function pointer relocations, which
we do not instrument, can be relaxed.
This patch also makes tagged-globals work properly with LTO, as
-Wa,-mrelax-relocations=no doesn't work with LTO.
Reviewed By: pcc
Differential Revision: https://reviews.llvm.org/D113220
Be more consistent in the naming convention for the various RET instructions to specify in terms of bitwidth.
Helps prevent future scheduler model mismatches like those that were only addressed in D44687.
Differential Revision: https://reviews.llvm.org/D113302
This moves the registry higher in the LLVM library dependency stack.
Every client of the target registry needs to link against MC anyway to
actually use the target, so we might as well move this out of Support.
This allows us to ensure that Support doesn't have includes from MC/*.
Differential Revision: https://reviews.llvm.org/D111454
This should have been the 4 byte version in the first place. Unfortunatelly there is no easy way to add a test as both the 1 byte and 4 byte version are printed as 'jmp' in the assembly code.
Reviewed By: kda
Differential Revision: https://reviews.llvm.org/D109453
In preparation for passing the MCSubtargetInfo (STI) through to writeNops
so that it can use the STI in operation at the time, we need to record the
STI in operation when a MCAlignFragment may write nops as padding. The
STI is currently unused, a further patch will pass it through to
writeNops.
There are many places that can create an MCAlignFragment, in most cases
we can find out the STI in operation at the time. In a few places this
isn't possible as we are in initialisation or finalisation, or are
emitting constant pools. When possible I've tried to find the most
appropriate existing fragment to obtain the STI from, when none is
available use the per module STI.
For constant pools we don't actually need to use EmitCodeAlign as the
constant pools are data anyway so falling through into it via an
executable NOP is no better than falling through into data padding.
This is a prerequisite for D45962 which uses the STI to emit the
appropriate NOP for the STI. Which can differ per fragment.
Note that involves an interface change to InitSections. It is now
called initSections and requires a SubtargetInfo as a parameter.
Differential Revision: https://reviews.llvm.org/D45961
Fixing this link error:
ld: error: relocation R_X86_64_PC32 cannot be used against symbol __asan_report_load...; recompile with -fPIC
Reviewed By: vitalybuka
Differential Revision: https://reviews.llvm.org/D109183
Looks like the NoRegister has some effect on the final code that is generated. My guess is that some optimization kicks in at the end?
When I use -S to dump the assembly I get the correct version with 'shrq $3, %r8':
movq %r9, %r8
shrq $3, %r8
movsbl 2147450880(%r8), %r8d
But, when I disassemble the final binary I get RAX in stead of R8:
mov %r9,%r8
shr $0x3,%rax
movsbl 0x7fff8000(%r8),%r8d
Reviewed By: vitalybuka
Differential Revision: https://reviews.llvm.org/D108745
The implementation uses the int_asan_check_memaccess intrinsic to instrument the code. The intrinsic is replaced by a call to a function which performs the access check. The generated function names encode the input register name as a number using Reg - X86::NoRegister formula.
Reviewed By: vitalybuka
Differential Revision: https://reviews.llvm.org/D107850
The implementation uses the int_asan_check_memaccess intrinsic to instrument the code. The intrinsic is replaced by a call to a function which performs the access check. The generated function names encode the input register name as a number using Reg - X86::NoRegister formula.
Reviewed By: vitalybuka
Differential Revision: https://reviews.llvm.org/D107850
As suggested on D107370, this patch renames the tuning feature flags to start with 'Tuning' instead of 'Feature'.
Differential Revision: https://reviews.llvm.org/D107459
<string> is currently the highest impact header in a clang+llvm build:
https://commondatastorage.googleapis.com/chromium-browser-clang/llvm-include-analysis.html
One of the most common places this is being included is the APInt.h header, which needs it for an old toString() implementation that returns std::string - an inefficient method compared to the SmallString versions that it actually wraps.
This patch replaces these APInt/APSInt methods with a pair of llvm::toString() helpers inside StringExtras.h, adjusts users accordingly and removes the <string> from APInt.h - I was hoping that more of these users could be converted to use the SmallString methods, but it appears that most end up creating a std::string anyhow. I avoided trying to use the raw_ostream << operators as well as I didn't want to lose having the integer radix explicit in the code.
Differential Revision: https://reviews.llvm.org/D103888
Current implementation assumes that, each MachineConstantPoolValue takes
up sizeof(MachineConstantPoolValue::Ty) bytes. For PowerPC, we want to
lump all the constants with the same type as one MachineConstantPoolValue
to save the cost that calculate the TOC entry for each const. So, we need
to extend the MachineConstantPoolValue that break this assumption.
Reviewed By: RKSimon
Differential Revision: https://reviews.llvm.org/D89108
The ABI demands a data16 prefix for lea in 64-bit LP64 mode, but not in
64-bit ILP32 mode. In both modes this prefix would ordinarily be
ignored, but the instructions may be changed by the linker to
instructions that are affected by the prefix.
Reviewed By: RKSimon
Differential Revision: https://reviews.llvm.org/D93157
Sometimes people get minimal crash reports after a UBSAN incident. This change
tags each trap with an integer representing the kind of failure encountered,
which can aid in tracking down the root cause of the problem.
LLVM has TLS_(base_)addr32 for 32-bit TLS addresses in 32-bit mode, and
TLS_(base_)addr64 for 64-bit TLS addresses in 64-bit mode. x32 mode wants 32-bit
TLS addresses in 64-bit mode, which were not yet handled. This adds
TLS_(base_)addrX32 as copies of TLS_(base_)addr64, except that they use
tls32(base)addr rather than tls64(base)addr, and then restricts
TLS_(base_)addr64 to 64-bit LP64 mode, TLS_(base_)addrX32 to 64-bit ILP32 mode.
Reviewed By: RKSimon
Differential Revision: https://reviews.llvm.org/D92346
Fangrui Song