Relocations of type R_WEBASSEMBLY_TABLE_INDEX represent places
where the table index for a given function is needed. While the
value stored in this location is a table index, the index in
the relocation entry itself is a function index (the index of
the function which is to be called indirectly).
This is how is was spec'd originally but the LLVM implementation
didn't do this. This makes things a little simpler in the linker
since the table in the input file can essentially be ignored that
the output table can be created purely based on these relocations.
Patch by Nicholas Wilson!
Differential Revision: https://reviews.llvm.org/D42080
llvm-svn: 323165
Summary:
This detects when an import library is about to be overwritten with a
newly built one with the same contents, and keeps the old library
instead. The use case for this is to avoid needlessly rebuilding
targets that depend on the import library in build systems that rely
on timestamps to determine whether a target requires rebuilding.
This feature was requested in PR35917.
Reviewers: rnk, ruiu, zturner, pcc
Reviewed By: ruiu
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D42326
llvm-svn: 323164
building method override tables for CXXMethodDecls in
DWARFASTParserClang::CompleteTypeFromDWARF.
C++ virtual method calls in LLDB expressions may fail if the override table for
the method being called is not correct as IRGen will produce references to the
wrong (or a missing) vtable entry.
This patch does not fix calls to virtual methods with covariant return types as
it mistakenly treats these as overloads, rather than overrides. This will be
addressed in a future patch.
Review: https://reviews.llvm.org/D41997
Partially fixes <rdar://problem/14205774>
llvm-svn: 323163
Summary:
One test-case uses a wrong operation (should be subtraction).
Second test-case should declare a global variables before a tested one
in order to guarantee we will find a red-zone.
Reviewers: kcc, jakubjelinek, alekseyshl
Reviewed By: alekseyshl
Subscribers: kubamracek
Differential Revision: https://reviews.llvm.org/D41481
llvm-svn: 323162
The original change was made based on a misunderstanding that
-DCMAKE_BUILD_TYPE=RelWithDebugInfo would produce the same executable
as -DCMAKE_BUILD_TYPE=Release modulo debug info. Turned out that's not
true -- it at least disables some optimizations such as function inlining.
llvm-svn: 323161
When a function taking transparent union is declared as taking one of
union members earlier in the translation unit, clang would hit an
"Invalid cast" assertion during EmitFunctionProlog. This case
corresponds to function f1 in test/CodeGen/transparent-union-redecl.c.
We decided to cast i32 to union because after merging function
declarations function parameter type becomes int,
CGFunctionInfo::ArgInfo type matches with ABIArgInfo type, so we decide
it is a trivial case. But these types should also be castable to
parameter declaration type which is not the case here.
Now the fix is in converting from ABIArgInfo type to VarDecl type and using
argument demotion when necessary.
Additional tests in Sema/transparent-union.c capture current behavior and make
sure there are no regressions.
rdar://problem/34949329
Reviewers: rjmccall, rafael
Reviewed By: rjmccall
Subscribers: aemerson, cfe-commits, kristof.beyls, ahatanak
Differential Revision: https://reviews.llvm.org/D41311
llvm-svn: 323156
Summary:
First, we need to explain the core of the vulnerability. Note that this
is a very incomplete description, please see the Project Zero blog post
for details:
https://googleprojectzero.blogspot.com/2018/01/reading-privileged-memory-with-side.html
The basis for branch target injection is to direct speculative execution
of the processor to some "gadget" of executable code by poisoning the
prediction of indirect branches with the address of that gadget. The
gadget in turn contains an operation that provides a side channel for
reading data. Most commonly, this will look like a load of secret data
followed by a branch on the loaded value and then a load of some
predictable cache line. The attacker then uses timing of the processors
cache to determine which direction the branch took *in the speculative
execution*, and in turn what one bit of the loaded value was. Due to the
nature of these timing side channels and the branch predictor on Intel
processors, this allows an attacker to leak data only accessible to
a privileged domain (like the kernel) back into an unprivileged domain.
The goal is simple: avoid generating code which contains an indirect
branch that could have its prediction poisoned by an attacker. In many
cases, the compiler can simply use directed conditional branches and
a small search tree. LLVM already has support for lowering switches in
this way and the first step of this patch is to disable jump-table
lowering of switches and introduce a pass to rewrite explicit indirectbr
sequences into a switch over integers.
However, there is no fully general alternative to indirect calls. We
introduce a new construct we call a "retpoline" to implement indirect
calls in a non-speculatable way. It can be thought of loosely as
a trampoline for indirect calls which uses the RET instruction on x86.
Further, we arrange for a specific call->ret sequence which ensures the
processor predicts the return to go to a controlled, known location. The
retpoline then "smashes" the return address pushed onto the stack by the
call with the desired target of the original indirect call. The result
is a predicted return to the next instruction after a call (which can be
used to trap speculative execution within an infinite loop) and an
actual indirect branch to an arbitrary address.
On 64-bit x86 ABIs, this is especially easily done in the compiler by
using a guaranteed scratch register to pass the target into this device.
For 32-bit ABIs there isn't a guaranteed scratch register and so several
different retpoline variants are introduced to use a scratch register if
one is available in the calling convention and to otherwise use direct
stack push/pop sequences to pass the target address.
This "retpoline" mitigation is fully described in the following blog
post: https://support.google.com/faqs/answer/7625886
We also support a target feature that disables emission of the retpoline
thunk by the compiler to allow for custom thunks if users want them.
These are particularly useful in environments like kernels that
routinely do hot-patching on boot and want to hot-patch their thunk to
different code sequences. They can write this custom thunk and use
`-mretpoline-external-thunk` *in addition* to `-mretpoline`. In this
case, on x86-64 thu thunk names must be:
```
__llvm_external_retpoline_r11
```
or on 32-bit:
```
__llvm_external_retpoline_eax
__llvm_external_retpoline_ecx
__llvm_external_retpoline_edx
__llvm_external_retpoline_push
```
And the target of the retpoline is passed in the named register, or in
the case of the `push` suffix on the top of the stack via a `pushl`
instruction.
There is one other important source of indirect branches in x86 ELF
binaries: the PLT. These patches also include support for LLD to
generate PLT entries that perform a retpoline-style indirection.
The only other indirect branches remaining that we are aware of are from
precompiled runtimes (such as crt0.o and similar). The ones we have
found are not really attackable, and so we have not focused on them
here, but eventually these runtimes should also be replicated for
retpoline-ed configurations for completeness.
For kernels or other freestanding or fully static executables, the
compiler switch `-mretpoline` is sufficient to fully mitigate this
particular attack. For dynamic executables, you must compile *all*
libraries with `-mretpoline` and additionally link the dynamic
executable and all shared libraries with LLD and pass `-z retpolineplt`
(or use similar functionality from some other linker). We strongly
recommend also using `-z now` as non-lazy binding allows the
retpoline-mitigated PLT to be substantially smaller.
When manually apply similar transformations to `-mretpoline` to the
Linux kernel we observed very small performance hits to applications
running typical workloads, and relatively minor hits (approximately 2%)
even for extremely syscall-heavy applications. This is largely due to
the small number of indirect branches that occur in performance
sensitive paths of the kernel.
When using these patches on statically linked applications, especially
C++ applications, you should expect to see a much more dramatic
performance hit. For microbenchmarks that are switch, indirect-, or
virtual-call heavy we have seen overheads ranging from 10% to 50%.
However, real-world workloads exhibit substantially lower performance
impact. Notably, techniques such as PGO and ThinLTO dramatically reduce
the impact of hot indirect calls (by speculatively promoting them to
direct calls) and allow optimized search trees to be used to lower
switches. If you need to deploy these techniques in C++ applications, we
*strongly* recommend that you ensure all hot call targets are statically
linked (avoiding PLT indirection) and use both PGO and ThinLTO. Well
tuned servers using all of these techniques saw 5% - 10% overhead from
the use of retpoline.
We will add detailed documentation covering these components in
subsequent patches, but wanted to make the core functionality available
as soon as possible. Happy for more code review, but we'd really like to
get these patches landed and backported ASAP for obvious reasons. We're
planning to backport this to both 6.0 and 5.0 release streams and get
a 5.0 release with just this cherry picked ASAP for distros and vendors.
This patch is the work of a number of people over the past month: Eric, Reid,
Rui, and myself. I'm mailing it out as a single commit due to the time
sensitive nature of landing this and the need to backport it. Huge thanks to
everyone who helped out here, and everyone at Intel who helped out in
discussions about how to craft this. Also, credit goes to Paul Turner (at
Google, but not an LLVM contributor) for much of the underlying retpoline
design.
Reviewers: echristo, rnk, ruiu, craig.topper, DavidKreitzer
Subscribers: sanjoy, emaste, mcrosier, mgorny, mehdi_amini, hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D41723
llvm-svn: 323155
This was added to mimic ELF, but maintaining it has cost
and we currently don't have any use for it outside of the
test code.
Differential Revision: https://reviews.llvm.org/D42324
llvm-svn: 323154
- Change inserted add ( V_ADD_{I|U}32_e32 ) to _e64 version ( V_ADD_{I|U}32_e64 ) so that the add uses a vreg for the carry; this prevents inserted v_add from killing VCC; the _e64 version doesn't accept a literal in its encoding, so we need to introduce a mov instr as well to get the imm into a register.
- Change pass name to "SI Load Store Optimizer"; this removes the '/', which complicates scripts.
Differential Revision: https://reviews.llvm.org/D42124
llvm-svn: 323153
The check (inside StackHintGeneratorForSymbol::getMessage)
if (!N)
return getMessageForSymbolNotFound()
is moved to the beginning of the function.
Differential revision: https://reviews.llvm.org/D42388
Test plan: make check-all
llvm-svn: 323146
When CMAKE_SYSROOT or CMAKE_FIND_ROOT_PATH is set, cmake
recommends setting CMAKE_FIND_ROOT_PATH_MODE_INCLUDE=ONLY
globally which means find_path() always prepends CMAKE_SYSROOT or
CMAKE_FIND_ROOT_PATH to all paths used in the search.
However, these find_path() invocations are looking for paths in
the libcxx and libunwind projects on the host system, not the
target system, which can be done by passing
NO_CMAKE_FIND_ROOT_PATH.
Differential Revision: https://reviews.llvm.org/D41623
llvm-svn: 323145
For sections with different virtual and physical addresses, alignment and
placement in the output binary should be based on the physical address.
Ran into this problem with a bare metal ARM project where llvm-objcopy added a
lot of zero-padding before the .data section that had differing addresses. GNU
objcopy did not add the padding, and after this fix, neither does llvm-objcopy.
Update a test case so a section has different physical and virtual addresses.
Fixes B35708
Authored By: Owen Shaw (owenpshaw)
Differential Revision: https://reviews.llvm.org/D41619
llvm-svn: 323144
When CMAKE_SYSROOT or CMAKE_FIND_ROOT_PATH is set, cmake
recommends setting CMAKE_FIND_ROOT_PATH_MODE_INCLUDE=ONLY
globally which means find_path() always prepends CMAKE_SYSROOT or
CMAKE_FIND_ROOT_PATH to all paths used in the search.
However, this find_path() invocation is looking for a path in the
libcxxabi project on the host system, not the target system,
which can be done by passing NO_CMAKE_FIND_ROOT_PATH.
Differential Revision: https://reviews.llvm.org/D41622
llvm-svn: 323143
When CMAKE_SYSROOT or CMAKE_FIND_ROOT_PATH is set, cmake
recommends setting CMAKE_FIND_ROOT_PATH_MODE_INCLUDE=ONLY
globally which means find_path() always prepends CMAKE_SYSROOT or
CMAKE_FIND_ROOT_PATH to all paths used in the search.
However, this find_path() invocation is looking for a path in the
libcxx project on the host system, not the target system,
which can be done by passing NO_CMAKE_FIND_ROOT_PATH.
Differential Revision: https://reviews.llvm.org/D41621
llvm-svn: 323141
Currently ASan instrumentation pass forces callback
instrumentation when applied to the kernel.
This patch changes the current behavior to allow
using inline instrumentation in this case.
Authored by andreyknvl. Reviewed in:
https://reviews.llvm.org/D42384
llvm-svn: 323140
Summary: We can't use unique_ptr's here because we use those variables as `out` parameters to some functions. Discovered by the memory sanitizer.
Subscribers: lldb-commits
Differential Revision: https://reviews.llvm.org/D42386
llvm-svn: 323138
As noted in another review, this loop is confusing. This commit cleans it up
somewhat.
Differential Revision: https://reviews.llvm.org/D42312
llvm-svn: 323136
Use 'unsigned' for these bitfields so they actually pack together.
Previously it used three words for these bits instead of one.
Add some static_asserts to prevent this from being undone.
llvm-svn: 323135
Summary:
The debian8 repos have an old version of ninja that seems to sometimes crash
when building llvm.
Reviewers: ioeric, mehdi_amini
Reviewed By: ioeric
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D42304
llvm-svn: 323134
Summary:
This patch removes IdentifierInfo from completion token after remembering
the identifier in the preprocessor.
Prior to this patch, completion token had the IdentifierInfo set to null when
completing at the start of identifier and to the II for completion prefix
when in the middle of identifier.
This patch unifies how code completion token is handled when it is insterted
before the identifier and in the middle of the identifier.
The actual IdentifierInfo can still be obtained from the Preprocessor.
Reviewers: bkramer, arphaman
Reviewed By: bkramer
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D42241
llvm-svn: 323133
Dsp and dspr2 require MIPS revision 2, while msa requires revision 5. Adding
warnings for cases when these flags are used with earlier revision.
Patch by Milos Stojanovic.
Differential Revision: https://reviews.llvm.org/D40490
llvm-svn: 323131
Summary:
The existing option objc-property-declaration.Acronyms
replaces the built-in set of acronyms.
While this behavior is OK for clients that don't want the default
behavior, many clients may just want to add their own custom acronyms
to the default list.
This revision introduces a new option,
objc-property-declaration.IncludeDefaultAcronyms, which controls
whether the acronyms in objc-property-declaration.Acronyms are
appended to the default list (the default behavior) or whether they
replace.
I also updated the documentation.
Test Plan: make -j12 check-clang-tools
Reviewers: Wizard, hokein, klimek
Reviewed By: hokein
Subscribers: Eugene.Zelenko, cfe-commits
Differential Revision: https://reviews.llvm.org/D42261
llvm-svn: 323130
The change in r322988 caused a failure in the bootstrap build bot.
The problem was that directly gluing a BR_CCMASK node to a
compare-and-swap could lead to issues if other nodes were
chained in between. There is then no way to create a topological
sort that respects both the chain sequence and the glue property.
Fixed for now by rejecting the optimization in this case. As a
future enhancement, we may be able to handle additional cases
by swapping chain links around.
llvm-svn: 323129
Summary:
The MultiplexExternalSemaSource doesn't correctly overload the `getModule` function,
causing the multiplexer to not forward this call as intended.
Reviewers: v.g.vassilev
Reviewed By: v.g.vassilev
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D39416
llvm-svn: 323122
Summary:
`m_last_tok` isn't initialized anywhere before it's used the first time (most likely in the `GoParser::Rule::error` method), which causes most of the GoParser tests to fail with sanitizers enabled with errors like this:
```
GoParser.cpp:52:21: runtime error: load of value <random value>, which is not a valid value for type 'GoLexer::TokenType'
UndefinedBehaviorSanitizer: undefined-behavior GoParser.cpp:52:21
```
Reviewers: ribrdb, davide, labath
Reviewed By: labath
Subscribers: labath, lldb-commits
Differential Revision: https://reviews.llvm.org/D42339
llvm-svn: 323119
Improves the code generation for v4f16 FCMP instructions when FullFP16 is not supported.
Generating FCTVL(s) rather than a longer series of FCVTs.
Differential Revision: https://reviews.llvm.org/D41772
llvm-svn: 323118
This frees up the first name to be used as an base class for the
apple table and the dwarf5 .debug_names accel table. The rename was
split off from D42297 (adding of debug_names support), which is still
under review.
llvm-svn: 323113
Primarily, this allows us to use the aggressive extraction mechanisms in combineExtractWithShuffle earlier and make use of UNDEF elements that may be lost during lowering.
Reapplied after rL322279 was reverted at rL322335 due to PR35918, underlying issue was fixed at rL322644.
llvm-svn: 323104
Summary: I will replace the existing URI struct in Protocol.h with the new URI and rename FileURI to URI in a followup patch.
Reviewers: sammccall
Reviewed By: sammccall
Subscribers: jkorous-apple, klimek, mgorny, ilya-biryukov, cfe-commits
Differential Revision: https://reviews.llvm.org/D41946
llvm-svn: 323101
Sam Clegg