| #
363496 |
|
24-Jul-2020 |
dim |
Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
10.0.1 final (aka llvmorg-10.0.1-0-gef32c611aa2).
MFC r360702:
Merge commit 4ca2cad94 from llvm git (by Justin Hibbits):
[PowerPC] Add clang -msvr4-struct-return for 32-bit ELF
Summary:
Change the default ABI to be compatible with GCC. For 32-bit ELF
targets other than Linux, Clang now returns small structs in
registers r3/r4. This affects FreeBSD, NetBSD, OpenBSD. There is no
change for 32-bit Linux, where Clang continues to return all structs
in memory.
Add clang options -maix-struct-return (to return structs in memory)
and -msvr4-struct-return (to return structs in registers) to be
compatible with gcc. These options are only for PPC32; reject them on
PPC64 and other targets. The options are like -fpcc-struct-return and
-freg-struct-return for X86_32, and use similar code.
To actually return a struct in registers, coerce it to an integer of
the same size. LLVM may optimize the code to remove unnecessary
accesses to memory, and will return i32 in r3 or i64 in r3:r4.
Fixes PR#40736
Patch by George Koehler!
Reviewed By: jhibbits, nemanjai
Differential Revision: https://reviews.llvm.org/D73290
Requested by: jhibbits
MFC r361410:
Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
llvmorg-10.0.1-rc1-0-gf79cd71e145 (aka 10.0.1 rc1).
MFC r362235 (by kp):
llvm: Default to -mno-relax on RISC-V
Compiling on a RISC-V system fails with 'relocation R_RISCV_ALIGN
requires unimplemented linker relaxation; recompile with -mno-relax'.
Our default linker (ld.lld) doesn't support relaxation, so default to
no-relax so we don't generate object files the linker can't handle.
Reviewed by: mhorne
Sponsored by: Axiado
Differential Revision: https://reviews.freebsd.org/D25210
MFC r362445:
Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
llvmorg-10.0.0-97-g6f71678ecd2 (not quite 10.0.1 rc2, as more fixes are
still pending).
MFC r362587 (by cem):
Add WITH_CLANG_FORMAT option
clang-format is enabled conditional on either WITH_CLANG_EXTRAS or
WITH_CLANG_FORMAT. Some sources in libclang are build conditional on
either rule, and obviously the clang-format binary itself depends on the
rule.
clang-format could still use a manual page.
Reviewed by: emaste
Differential Revision: https://reviews.freebsd.org/D25427
MFC r362609:
Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
llvmorg-10.0.0-129-gd24d5c8e308. Getting closer to 10.0.1-rc2.
MFC r362679:
Regenerate ReStructuredText based manpages for llvm-project tools:
* bugpoint.1
* clang.1
* llc.1
* lldb.1
* lli.1
* llvm-ar.1
* llvm-as.1
* llvm-bcanalyzer.1
* llvm-cov.1
* llvm-diff.1
* llvm-dis.1
* llvm-dwarfdump.1
* llvm-extract.1
* llvm-link.1
* llvm-mca.1
* llvm-nm.1
* llvm-pdbutil.1
* llvm-profdata.1
* llvm-symbolizer.1
* llvm-tblgen.1
* opt.1
Add newly generated manpages for:
* llvm-addr2line.1 (this is an alias of llvm-symbolizer)
* llvm-cxxfilt.1
* llvm-objcopy.1
* llvm-ranlib.1 (this is an alias of llvm-ar)
Note that llvm-objdump.1 is an exception, as upstream has both a plain
.1 file, and a .rst variant. These will have to be reconciled upstream
first.
MFC r362680:
Follow-up to r362679, add more entries to OptionalObsoleteFiles.inc
MFC r362719:
Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
llvmorg-10.0.1-rc2-0-g77d76b71d7d.
Also add a few more llvm utilities under WITH_CLANG_EXTRAS:
* llvm-dwp, a utility for merging DWARF 5 Split DWARF .dwo files into
.dwp (DWARF package files)
* llvm-size, a size(1) replacement
* llvm-strings, a strings(1) replacement
MFC r362733:
Remove older llvm-ranlib.1 entry from ObsoleteFiles.inc, as it has
gotten its own manpage now, and should be no longer be removed by "make
delete-old".
MFC r362734:
Fix llvm-strings.1 not installing, this was a copy/paste error.
MFC r363401:
Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
10.0.1 final (aka llvmorg-10.0.1-0-gef32c611aa2).
There were no changes since rc2, except in the upstream regression
tests, which we do not ship.
Relnotes: yes
|
| #
344213 |
|
16-Feb-2019 |
dim |
Merge clang 7.0.1 and several follow-up changes
MFC r318594:
Add libc++experimental.a for std::experimental support
This adds a separate library for supporting std::experimental features.
It is purposefully static, and must be explicitly linked into programs
using -lc++experimental.
PLEASE NOTE: there is NO WARRANTY as to any stability or continuing
existence of the features in the std::experimental parts of the C++
library!
Reviewed by: ed
Differential Revision: https://reviews.freebsd.org/D10840
MFC r318598:
Add PICFLAG to build libc++experimental.a, so it can be used in all
situations.
Noticed by: kib
r336969 | emaste | 2018-07-31 16:12:09 +0200 (Tue, 31 Jul 2018) | 13 lines
llvm: [ELF][ARM] Add Arm ABI names for float ABI ELF Header flags
The ELF for the Arm architecture document defines, for EF_ARM_EABI_VER5
and above, the flags EF_ARM_ABI_FLOAT_HARD and EF_ARM_ABI_FLOAT_SOFT.
These have been defined to be compatible with the existing
EF_ARM_VFP_FLOAT and EF_ARM_SOFT_FLOAT used by gcc for
EF_ARM_EABI_UNKNOWN.
This patch adds the flags in addition to the existing ones so that any
code depending on the old names will still work.
Obtained from: llvm r338370 by Peter Smith
r336970 | emaste | 2018-07-31 16:14:41 +0200 (Tue, 31 Jul 2018) | 9 lines
llvm: [ARM] Complete enumeration values for Tag_ABI_VFP_args
The LLD implementation of Tag_ABI_VFP_args needs to check the rarely
seen values of 3 (toolchain specific) and 4 compatible with both Base
and VFP. Add the missing enumeration values so that LLD can refer to
them without having to use the raw numbers.
Obtained from: llvm r338373 by Peter Smith
r336972 | emaste | 2018-07-31 17:25:03 +0200 (Tue, 31 Jul 2018) | 37 lines
lld: [ELF][ARM] Implement support for Tag_ABI_VFP_args
The Tag_ABI_VFP_args build attribute controls the procedure call
standard used for floating point parameters on ARM. The values are:
0 - Base AAPCS (FP Parameters passed in Core (Integer) registers
1 - VFP AAPCS (FP Parameters passed in FP registers)
2 - Toolchain specific (Neither Base or VFP)
3 - Compatible with all (No use of floating point parameters)
If the Tag_ABI_VFP_args build attribute is missing it has an implicit
value of 0.
We use the attribute in two ways:
* Detect a clash in calling convention between Base, VFP and Toolchain.
we follow ld.bfd's lead and do not error if there is a clash between an
implicit Base AAPCS caused by a missing attribute. Many projects
including the hard-float (VFP AAPCS) version of glibc contain assembler
files that do not use floating point but do not have Tag_ABI_VFP_args.
* Set the EF_ARM_ABI_FLOAT_SOFT or EF_ARM_ABI_FLOAT_HARD ELF header flag
for Base or VFP AAPCS respectively. This flag is used by some ELF
loaders.
References:
* Addenda to, and Errata in, the ABI for the ARM Architecture for
Tag_ABI_VFP_args
* Elf for the ARM Architecture for ELF header flags
Fixes LLVM PR36009
PR: 229050
Obtained from: llvm r338377 by Peter Smith
r337282 | alc | 2018-08-04 04:30:51 +0200 (Sat, 04 Aug 2018) | 7 lines
Set the default image base on arm64 and i386 to a superpage-aligned
address.
Reviewed by: emaste, markj
Discussed with: dim
Differential Revision: https://reviews.freebsd.org/D16385
r339304 | emaste | 2018-10-11 15:19:17 +0200 (Thu, 11 Oct 2018) | 13 lines
lld: set sh_link and sh_info for .rela.plt sections
ELF spec says that for SHT_REL and SHT_RELA sh_link should reference the
associated string table and sh_info should reference the "section to
which the relocation applies." ELF Tool Chain's elfcopy / strip use
this (in part) to control whether or not the relocation entry is copied
to the output.
LLVM PR 37538 https://bugs.llvm.org/show_bug.cgi?id=37538
Approved by: re (kib)
Obtained from: llvm r344226 (backported for 6.0)
MFC r341825:
Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
the upstream release_70 branch r348686 (effectively, 7.0.1 rc3). The
release will follow very soon, but no more functional changes are
expected.
Release notes for llvm, clang and lld 7.0.0 are available here:
<http://releases.llvm.org/7.0.0/docs/ReleaseNotes.html>
<http://releases.llvm.org/7.0.0/tools/clang/docs/ReleaseNotes.html>
<http://releases.llvm.org/7.0.0/tools/lld/docs/ReleaseNotes.html>
PR: 230240, 230355
Relnotes: yes
MFC r342123:
Update clang, llvm, lld, lldb, compiler-rt and libc++ version number to
7.0.1 release r349250. There were no functional changes since the 7.0.1
rc3 import.
PR: 230240, 230355
Relnotes: yes
r343429 | emaste | 2019-01-25 15:46:13 +0100 (Fri, 25 Jan 2019) | 16 lines
clang: default to DWARF 4 as of FreeBSD 13
FreeBSD previously defaulted to DWARF 2 because several tools (gdb,
ctfconvert, etc.) did not support later versions. These have either
been fixed or are deprecated.
Note that gdb 6 still exists but has been moved out of $PATH into
/usr/libexec and is intended only for use by crashinfo(8). The kernel
build sets the DWARF version explicitly via -gdwarf2, so this should
have no effect there.
PR: 234887 [exp-run]
Reviewed by: markj
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D17930
MFC r343916:
Pull in r352607 from upstream llvm trunk (by Craig Topper):
[X86] Add FPSW as a Def on some FP instructions that were missing it.
Pull in r353141 from upstream llvm trunk (by Craig Topper):
[X86] Connect the default fpsr and dirflag clobbers in inline
assembly to the registers we have defined for them.
Summary:
We don't currently map these constraints to physical register numbers
so they don't make it to the MachineIR representation of inline
assembly.
This could have problems for proper dependency tracking in the
machine schedulers though I don't have a test case that shows that.
Reviewers: rnk
Reviewed By: rnk
Subscribers: eraman, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D57641
Pull in r353489 from upstream llvm trunk (by Craig Topper):
[X86] Add FPCW as a register and start using it as an implicit use on
floating point instructions.
Summary:
FPCW contains the rounding mode control which we manipulate to
implement fp to integer conversion by changing the roudning mode,
storing the value to the stack, and then changing the rounding mode
back. Because we didn't model FPCW and its dependency chain, other
instructions could be scheduled into the middle of the sequence.
This patch introduces the register and adds it as an implciit def of
FLDCW and implicit use of the FP binary arithmetic instructions and
store instructions. There are more instructions that need to be
updated, but this is a good start. I believe this fixes at least the
reduced test case from PR40529.
Reviewers: RKSimon, spatel, rnk, efriedma, andrew.w.kaylor
Subscribers: dim, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D57735
These should fix a problem in clang 7.0 where it would sometimes emit
long double floating point instructions in a slightly wrong order,
leading to failures in our libm tests. In particular, the cbrt_test
test case 'cbrtl_powl' and the trig_test test case 'reduction'.
Also bump __FreeBSD_cc_version, to be able to detect this in our test
suite.
Reported by: lwhsu
PR: 234040
Upstream PR: https://bugs.llvm.org/show_bug.cgi?id=40206
MFC r344056:
Pull in r339734 from upstream llvm trunk (by Eli Friedman):
[ARM] Make PerformSHLSimplify add nodes to the DAG worklist correctly.
Intentionally excluding nodes from the DAGCombine worklist is likely
to lead to weird optimizations and infinite loops, so it's generally
a bad idea.
To avoid the infinite loops, fix DAGCombine to use the
isDesirableToCommuteWithShift target hook before performing the
transforms in question, and implement the target hook in the ARM
backend disable the transforms in question.
Fixes https://bugs.llvm.org/show_bug.cgi?id=38530 . (I don't have a
reduced testcase for that bug. But we should have sufficient test
coverage for PerformSHLSimplify given that we're not playing weird
tricks with the worklist. I can try to bugpoint it if necessary,
though.)
Differential Revision: https://reviews.llvm.org/D50667
This should fix a possible hang when compiling sys/dev/nxge/if_nxge.c
(which exists now only in the stable/11 branch) for arm.
|
| #
331838 |
|
31-Mar-2018 |
dim |
Merge clang, llvm, lld, lldb, compiler-rt and libc++ 6.0.0 release, and
several follow-up fixes.
MFC r327952:
Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
6.0.0 (branches/release_60 r321788). Upstream has branched for the
6.0.0 release, which should be in about 6 weeks. Please report bugs and
regressions, so we can get them into the release.
Please note that from 3.5.0 onwards, clang, llvm and lldb require C++11
support to build; see UPDATING for more information.
MFC r328010:
Pull in r322473 from upstream llvm trunk (by Andrei Elovikov):
[LV] Don't call recordVectorLoopValueForInductionCast for
newly-created IV from a trunc.
Summary:
This method is supposed to be called for IVs that have casts in their
use-def chains that are completely ignored after vectorization under
PSE. However, for truncates of such IVs the same InductionDescriptor
is used during creation/widening of both original IV based on PHINode
and new IV based on TruncInst.
This leads to unintended second call to
recordVectorLoopValueForInductionCast with a VectorLoopVal set to the
newly created IV for a trunc and causes an assert due to attempt to
store new information for already existing entry in the map. This is
wrong and should not be done.
Fixes PR35773.
Reviewers: dorit, Ayal, mssimpso
Reviewed By: dorit
Subscribers: RKSimon, dim, dcaballe, hsaito, llvm-commits, hiraditya
Differential Revision: https://reviews.llvm.org/D41913
This should fix "Vector value already set for part" assertions when
building the net/iodine and sysutils/daa2iso ports.
Reported by: jbeich
PR: 224867, 224868
MFC r328090:
Pull in r322623 from upstream llvm trunk (by Andrew V. Tischenko):
Allow usage of X86-prefixes as separate instrs.
Differential Revision: https://reviews.llvm.org/D42102
This should fix parse errors when x86 prefixes (such as 'lock' and
'rep') are followed by various non-mnemonic tokens, e.g. comments, .byte
directives and labels.
PR: 224669, 225054
MFC r328091:
Revert r327340, as the workaround for rep prefixes followed by .byte
directives is no longer needed after r328090.
MFC r328141 (by emaste):
lld: Fix for ld.lld does not accept "AT" syntax for declaring LMA region
AT> lma_region expression allows to specify the memory region
for section load address.
Should fix [upstream LLVM] PR35684.
LLVM review: https://reviews.llvm.org/D41397
Obtained from: LLVM r322359 by George Rimar
MFC r328143 (by emaste):
lld: Handle parsing AT(ADDR(.foo-bar)).
The problem we had with it is that anything inside an AT is an
expression, so we failed to parse the section name because of the - in
it.
Requested by: royger
Obtained from: LLVM r322801 by Rafael Espindola
MFC r328144 (by emaste):
lld: Fix incorrect physical address on self-referencing AT command.
When a section placement (AT) command references the section itself,
the physical address of the section in the ELF header was calculated
incorrectly due to alignment happening right after the location
pointer's value was captured.
The problem was diagnosed and the first version of the patch written
by Erick Reyes.
Obtained from: LLVM r322421 by Rafael Espindola
MFC r328145:
Pull in r322016 from upstream llvm trunk (by Sanjay Patel):
[ValueTracking] remove overzealous assert
The test is derived from a failing fuzz test:
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=5008
Credit to @rksimon for pointing out the problem.
This should fix "Bad flavor while matching min/max" errors when building
the graphics/libsixel and science/kst2 ports.
Reported by: jbeich
PR: 225268, 225269
MFC r328146:
Pull in r322106 from upstream llvm trunk (by Alexey Bataev):
[COST]Fix PR35865: Fix cost model evaluation for shuffle on X86.
Summary:
If the vector type is transformed to non-vector single type, the
compile may crash trying to get vector information about non-vector
type.
Reviewers: RKSimon, spatel, mkuper, hfinkel
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D41862
This should fix "Not a vector MVT!" errors when building the
games/dhewm3 port.
Reported by: jbeich
PR: 225271
MFC r328286 (by emaste):
lld: Don't mark a shared library as needed because of a lazy symbol.
Obtained from: LLVM r323221 by Rafael Esp?ndola
MFC r328381:
Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
6.0.0 (branches/release_60 r323338).
PR: 224669
MFC r328513:
Pull in r322245 from upstream clang trunk (by Craig Topper):
[X86] Make -mavx512f imply -mfma and -mf16c in the frontend like it
does in the backend.
Similarly, make -mno-fma and -mno-f16c imply -mno-avx512f.
Withou this "-mno-sse -mavx512f" ends up with avx512f being enabled
in the frontend but disabled in the backend.
Reported by: pawel
PR: 225488
MFC r328542 (by emaste):
lld: Use lookup instead of find. NFC, just simpler.
Obtained from: LLVM r323395 by Rafael Espindola
MFC r328543 (by emaste):
lld: Only lookup LMARegion once. NFC.
This is similar to how we handle MemRegion.
Obtained from: LLVM r323396 by Rafael Espindola
MFC r328544 (by emaste):
lld: Remove MemRegionOffset. NFC.
We can just use a member variable in MemoryRegion.
Obtained from: LLVM r323399 by Rafael Espindola
MFC r328545 (by emaste):
lld: Simplify. NFC.
Obtained from: LLVM r323440 by Rafael Espindola
MFC r328546 (by emaste):
lld: Improve LMARegion handling.
This fixes the crash reported at [LLVM] PR36083.
The issue is that we were trying to put all the sections in the same
PT_LOAD and crashing trying to write past the end of the file.
This also adds accounting for used space in LMARegion, without it all
3 PT_LOADs would have the same physical address.
Obtained from: LLVM r323449 by Rafael Espindola
MFC r328547 (by emaste):
lld: Move LMAOffset from the OutputSection to the PhdrEntry. NFC.
If two sections are in the same PT_LOAD, their relatives offsets,
virtual address and physical addresses are all the same.
[Rafael] initially wanted to have a single global LMAOffset, on the
assumption that every ELF file was in practiced loaded contiguously in
both physical and virtual memory.
Unfortunately that is not the case. The linux kernel has:
LOAD 0x200000 0xffffffff81000000 0x0000000001000000 0xced000 0xced000 R E 0x200000
LOAD 0x1000000 0xffffffff81e00000 0x0000000001e00000 0x15f000 0x15f000 RW 0x200000
LOAD 0x1200000 0x0000000000000000 0x0000000001f5f000 0x01b198 0x01b198 RW 0x200000
LOAD 0x137b000 0xffffffff81f7b000 0x0000000001f7b000 0x116000 0x1ec000 RWE 0x200000
The delta for all but the third PT_LOAD is the same:
0xffffffff80000000. [Rafael] thinks the 3rd one is a hack for implementing
per cpu data, but we can't break that.
Obtained from: LLVM r323456 by Rafael Espindola
MFC r328548 (by emaste):
lld: Put the header in the first PT_LOAD even if that PT_LOAD has a LMAExpr
The root problem is that we were creating a PT_LOAD just for the header.
That was technically valid, but inconvenient: we should not be making
the ELF discontinuous.
The solution is to allow a section with LMAExpr to be added to a PT_LOAD
if that PT_LOAD doesn't already have a LMAExpr.
LLVM PR: 36017
Obtained from: LLVM r323625 by Rafael Espindola
MFC r328594 (by emaste):
Pull in r322108 from upstream llvm trunk (by Rafael Esp?ndola):
Make one of the emitFill methods non virtual. NFC.
This is just preparatory work to fix [LLVM] PR35858.
MFC r328595 (by emaste):
Pull in r322123 from upstream llvm trunk (by Rafael Esp?ndola):
Don't create MCFillFragment directly.
Instead use higher level APIs that take care of most bookkeeping.
MFC r328596 (by emaste):
Pull in r322131 from upstream llvm trunk (by Rafael Esp?ndola):
Use a MCExpr for the size of MCFillFragment.
This allows the size to be found during ralaxation. This fixes
[LLVM] pr35858.
Requested by: royger
MFC r328753:
Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
6.0.0 (branches/release_60 r323948).
PR: 224669
MFC r328817:
Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
6.0.0 (branches/release_60 r324090).
This introduces retpoline support, with the -mretpoline flag. The
upstream initial commit message (r323155 by Chandler Carruth) contains
quite a bit of explanation. Quoting:
Introduce the "retpoline" x86 mitigation technique for variant #2 of
the speculative execution vulnerabilities disclosed today,
specifically identified by CVE-2017-5715, "Branch Target Injection",
and is one of the two halves to Spectre.
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 typic al 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
PR: 224669
MFC r329033:
Pull in r324594 from upstream clang trunk (by Alexander Ivchenko):
Fix for #31362 - ms_abi is implemented incorrectly for values >=16
bytes.
Summary:
This patch is a fix for following issue:
https://bugs.llvm.org/show_bug.cgi?id=31362 The problem was caused by
front end lowering C calling conventions without taking into account
calling conventions enforced by attribute. In this case win64cc was
no correctly lowered on targets other than Windows.
Reviewed By: rnk (Reid Kleckner)
Differential Revision: https://reviews.llvm.org/D43016
Author: belickim <mateusz.belicki@intel.com>
This fixes clang 6.0.0 assertions when building the emulators/wine and
emulators/wine-devel ports, and should also make it use the correct
Windows calling conventions. Bump __FreeBSD_version to make the fix
easy to detect.
PR: 224863
MFC r329223:
Pull in r323998 from upstream clang trunk (by Richard Smith):
PR36157: When injecting an implicit function declaration in C89, find
the right DeclContext rather than injecting it wherever we happen to
be.
This avoids creating functions whose DeclContext is a struct or
similar.
This fixes assertion failures when parsing certain not-completely-valid
struct declarations.
Reported by: ae
PR: 225862
MFC r329410:
Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
6.0.0 (branches/release_60 r325330).
PR: 224669
MFC r329983:
Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
6.0.0 (branches/release_60 r325932). This corresponds to 6.0.0 rc3.
PR: 224669
MFC r330384:
Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
6.0.0 release (upstream r326565).
Release notes for llvm, clang and lld will be available here soon:
<http://releases.llvm.org/6.0.0/docs/ReleaseNotes.html>
<http://releases.llvm.org/6.0.0/tools/clang/docs/ReleaseNotes.html>
<http://releases.llvm.org/6.0.0/tools/lld/docs/ReleaseNotes.html>
Relnotes: yes
PR: 224669
MFC r330686:
Pull in r326882 from upstream llvm trunk (by Sjoerd Meijer):
[ARM] Fix for PR36577
Don't PerformSHLSimplify if the given node is used by a node that
also uses a constant because we may get stuck in an infinite combine
loop.
bugzilla: https://bugs.llvm.org/show_bug.cgi?id=36577
Patch by Sam Parker.
Differential Revision: https://reviews.llvm.org/D44097
This fixes a hang when compiling one particular file in java/openjdk8
for armv6 and armv7.
Reported by: swills
PR: 226388
MFC r331065:
Pull in r327638 from upstream llvm trunk (by Matthew Simpson):
[ConstantFolding, InstSimplify] Handle more vector GEPs
This patch addresses some additional cases where the compiler crashes
upon encountering vector GEPs. This should fix PR36116.
Differential Revision: https://reviews.llvm.org/D44219
Reference: https://bugs.llvm.org/show_bug.cgi?id=36116
This fixes an assertion when building the emulators/snes9x port.
Reported by: jbeich
PR: 225471
MFC r331066:
Pull in r321999 from upstream clang trunk (by Ivan A. Kosarev):
[CodeGen] Fix TBAA info for accesses to members of base classes
Resolves:
Bug 35724 - regression (r315984): fatal error: error in backend:
Broken function found (Did not see access type in access path!)
https://bugs.llvm.org/show_bug.cgi?id=35724
Differential Revision: https://reviews.llvm.org/D41547
This fixes "Did not see access type in access path" fatal errors when
building the devel/gdb port (version 8.1).
Reported by: jbeich
PR: 226658
MFC r331366:
Pull in r327101 from upstream llvm trunk (by Rafael Espindola):
Don't treat .symver as a regular alias definition.
This patch starts simplifying the handling of .symver.
For now it just moves the responsibility for creating an alias down to
the streamer. With that the asm streamer can pass a .symver unchanged,
which is nice since gas cannot parse "foo@bar = zed".
In a followup I hope to move the handling down to the writer so that
we don't need special hacks for avoiding breaking names with @@@ on
windows.
Pull in r327160 from upstream llvm trunk (by Rafael Espindola):
Delay creating an alias for @@@.
With this we only create an alias for @@@ once we know if it should
use @ or @@. This avoids last minutes renames and hacks to handle MS
names.
This only handles the ELF writer. LTO still has issues with @@@
aliases.
Pull in r327928 from upstream llvm trunk (by Vitaly Buka):
Object: Move attribute calculation into RecordStreamer. NFC
Summary: Preparation for D44274
Reviewers: pcc, espindola
Subscribers: hiraditya
Differential Revision: https://reviews.llvm.org/D44276
Pull in r327930 from upstream llvm trunk (by Vitaly Buka):
Object: Fix handling of @@@ in .symver directive
Summary:
name@@@nodename is going to be replaced with name@@nodename if symbols is
defined in the assembled file, or name@nodename if undefined.
https://sourceware.org/binutils/docs/as/Symver.html
Fixes PR36623
Reviewers: pcc, espindola
Subscribers: mehdi_amini, hiraditya
Differential Revision: https://reviews.llvm.org/D44274
Together, these changes fix handling of @@@ in .symver directives when
doing Link Time Optimization.
Reported by: Shawn Webb <shawn.webb@hardenedbsd.org>
MFC r331731:
Pull in r328738 from upstream lld trunk (by Rafael Espindola):
Strip @VER suffices from the LTO output.
This fixes pr36623.
The problem is that we have to parse versions out of names before LTO
so that LTO can use that information.
When we get the LTO produced .o files, we replace the previous symbols
with the LTO produced ones, but they still have @ in their names.
We could just trim the name directly, but calling parseSymbolVersion
to do it is simpler.
This is a follow-up to r331366, since we discovered that lld could
append version strings to symbols twice, when using Link Time
Optimization.
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