Commit Graph

12813 Commits

Author SHA1 Message Date
Fangrui Song dbd7281aa7 [ELF] Shuffle .init_array/.fini_array with --shuffle-sections=
Useful for detecting static initialization order fiasco.

Reviewed By: grimar

Differential Revision: https://reviews.llvm.org/D74887
2020-02-21 08:16:07 -08:00
Fangrui Song de0dda54d3 [ELF] Warn changed output section address
When the output section address (addrExpr) is specified, GNU ld warns if
sh_addr is different. This patch implements the warning.

Note, LinkerScript::assignAddresses can be called more than once. We
need to record the changed section addresses, and only report the
warnings after the addresses are finalized.

Reviewed By: grimar

Differential Revision: https://reviews.llvm.org/D74741
2020-02-21 08:13:29 -08:00
Fangrui Song 6ed8e20143 [ELF] Ignore the maximum of input section alignments for two cases
Follow-up for D74286.

Notations:

* alignExpr: the computed ALIGN value
* max_input_align: the maximum of input section alignments

This patch changes the following two cases to match GNU ld:

* When ALIGN is present, GNU ld sets output sh_addr to alignExpr, while lld use max(alignExpr, max_input_align)
* When addrExpr is specified but alignExpr is not, GNU ld sets output sh_addr to addrExpr, while lld uses `advance(0, max_input_align)`

Note, sh_addralign is still set to max(alignExpr, max_input_align).

lma-align.test is enhanced a bit to check we don't overalign sh_addr.

fixSectionAlignments() sets addrExpr but not alignExpr for the `!hasSectionsCommand` case.
This patch sets alignExpr as well so that max_input_align will be respected.

Reviewed By: grimar

Differential Revision: https://reviews.llvm.org/D74736
2020-02-21 08:12:00 -08:00
Tamas Petz 14d7b802db [LLD][ELF][ARM] Add test cases for R_ARM_THM_MOV*-type relocs
Summary: This patch adds missing tests cases for R_ARM_THM_MOVW/MOVT* relocations for the sake of completeness.

Reviewers: peter.smith, MaskRay, espindola, psmith

Reviewed By: MaskRay, psmith

Subscribers: psmith, danielkiss, emaste, kristof.beyls, llvm-commits

Tags: #llvm, #lld

Differential Revision: https://reviews.llvm.org/D74827
2020-02-20 10:00:42 +01:00
Fangrui Song d6d640ebae [ELF][test] Fix section sh_type and sh_flags
A future MC change may add a warning/error when a .section directive
specifies incorrect sh_flags/sh_type.
2020-02-19 22:01:42 -08:00
Sam Clegg 06f1a5c9c2 [lld][WebAssembly] Allow symbols with explict import names to be undefined at link time.
Differential Revision: https://reviews.llvm.org/D74110
2020-02-19 18:02:49 -08:00
Sam Clegg bd4812776b [WebAssembly] Use llvm::Optional to store optional symbol attributes. NFC.
The changes the in-memory representation of wasm symbols such that their
optional ImportName and ImportModule use llvm::Optional.

ImportName is set whenever WASM_SYMBOL_EXPLICIT_NAME flag is set.
ImportModule (for imports) is currently always set since it defaults to
"env".

In the future we can possibly extent to binary format distingish
import which have explit module names.

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D74109
2020-02-19 17:25:33 -08:00
Fangrui Song 878159038b [ELF][test] Fix --symbol-ordering-file tests of shuffle_sections.s 2020-02-19 17:13:06 -08:00
Fangrui Song 40463301e4 [ELF][test] Fix shuffle_sections.s
C++ standard libraries have different random function implementations.
We cannot expect a particular order.
2020-02-19 17:10:32 -08:00
Rafael Ávila de Espíndola d48d339156 [lld][ELF] Add --shuffle-sections=seed to shuffle input sections
Summary:
This option causes lld to shuffle sections by assigning different
priorities in each run.

The use case for this is to introduce randomization in benchmarks. The
idea is inspired by the paper "Producing Wrong Data Without Doing
Anything Obviously Wrong!"
(https://www.inf.usi.ch/faculty/hauswirth/publications/asplos09.pdf). Unlike
the paper, we shuffle individual sections, not just input files.

Doing this in lld is particularly convenient as the --reproduce option
makes it easy to collect all the necessary bits for relinking the
program being benchmarked. Once that it is done, all that is needed is
to add --shuffle-sections=0 to the response file and relink before each
run of the benchmark.

Differential Revision: https://reviews.llvm.org/D74791
2020-02-19 13:44:12 -08:00
Tamas Petz 6e326882da [LLD][ELF][ARM] Fix support for SBREL type relocations
With this patch lld recognizes ARM SBREL relocations.
R_ARM*_MOVW_BREL relocations are not tested because they are not used.

Patch by Tamas Petz

Differential Revision: https://reviews.llvm.org/D74604
2020-02-19 10:07:46 +00:00
Daniel Kiss b6162622c0 [LLD][ELF][AArch64] Change the semantics of -z pac-plt.
Summary:
Generate PAC protected plt only when "-z pac-plt" is passed to the
linker. GNU toolchain generates when it is explicitly requested[1].
When pac-plt is requested then set the GNU_PROPERTY_AARCH64_FEATURE_1_PAC
note even when not all function compiled with PAC but issue a warning.
Harmonizing the warning style for BTI/PAC/IBT.
Generate BTI protected PLT if case of "-z force-bti".

[1] https://www.sourceware.org/ml/binutils/2019-03/msg00021.html

Reviewers: peter.smith, espindola, MaskRay, grimar

Reviewed By: peter.smith, MaskRay

Subscribers: tatyana-krasnukha, emaste, arichardson, kristof.beyls, MaskRay, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D74537
2020-02-18 09:56:57 +01:00
Alexandre Ganea 8404aeb56a [Support] On Windows, ensure hardware_concurrency() extends to all CPU sockets and all NUMA groups
The goal of this patch is to maximize CPU utilization on multi-socket or high core count systems, so that parallel computations such as LLD/ThinLTO can use all hardware threads in the system. Before this patch, on Windows, a maximum of 64 hardware threads could be used at most, in some cases dispatched only on one CPU socket.

== Background ==
Windows doesn't have a flat cpu_set_t like Linux. Instead, it projects hardware CPUs (or NUMA nodes) to applications through a concept of "processor groups". A "processor" is the smallest unit of execution on a CPU, that is, an hyper-thread if SMT is active; a core otherwise. There's a limit of 32-bit processors on older 32-bit versions of Windows, which later was raised to 64-processors with 64-bit versions of Windows. This limit comes from the affinity mask, which historically is represented by the sizeof(void*). Consequently, the concept of "processor groups" was introduced for dealing with systems with more than 64 hyper-threads.

By default, the Windows OS assigns only one "processor group" to each starting application, in a round-robin manner. If the application wants to use more processors, it needs to programmatically enable it, by assigning threads to other "processor groups". This also means that affinity cannot cross "processor group" boundaries; one can only specify a "preferred" group on start-up, but the application is free to allocate more groups if it wants to.

This creates a peculiar situation, where newer CPUs like the AMD EPYC 7702P (64-cores, 128-hyperthreads) are projected by the OS as two (2) "processor groups". This means that by default, an application can only use half of the cores. This situation could only get worse in the years to come, as dies with more cores will appear on the market.

== The problem ==
The heavyweight_hardware_concurrency() API was introduced so that only *one hardware thread per core* was used. Once that API returns, that original intention is lost, only the number of threads is retained. Consider a situation, on Windows, where the system has 2 CPU sockets, 18 cores each, each core having 2 hyper-threads, for a total of 72 hyper-threads. Both heavyweight_hardware_concurrency() and hardware_concurrency() currently return 36, because on Windows they are simply wrappers over std:🧵:hardware_concurrency() -- which can only return processors from the current "processor group".

== The changes in this patch ==
To solve this situation, we capture (and retain) the initial intention until the point of usage, through a new ThreadPoolStrategy class. The number of threads to use is deferred as late as possible, until the moment where the std::threads are created (ThreadPool in the case of ThinLTO).

When using hardware_concurrency(), setting ThreadCount to 0 now means to use all the possible hardware CPU (SMT) threads. Providing a ThreadCount above to the maximum number of threads will have no effect, the maximum will be used instead.
The heavyweight_hardware_concurrency() is similar to hardware_concurrency(), except that only one thread per hardware *core* will be used.

When LLVM_ENABLE_THREADS is OFF, the threading APIs will always return 1, to ensure any caller loops will be exercised at least once.

Differential Revision: https://reviews.llvm.org/D71775
2020-02-14 10:24:22 -05:00
Fangrui Song 105a270028 [ELF][AArch64] Rename pacPlt to zPacPlt and forceBti to zForceIbt after D71327. NFC
We use config->z* for -z options.
2020-02-13 21:02:54 -08:00
Yuanfang Chen 4ad7685258 Revert "Revert "Reland "[Support] make report_fatal_error `abort` instead of `exit`"""
This reverts commit 80a34ae311 with fixes.

Previously, since bots turning on EXPENSIVE_CHECKS are essentially turning on
MachineVerifierPass by default on X86 and the fact that
inline-asm-avx-v-constraint-32bit.ll and inline-asm-avx512vl-v-constraint-32bit.ll
are not expected to generate functioning machine code, this would go
down to `report_fatal_error` in MachineVerifierPass. Here passing
`-verify-machineinstrs=0` to make the intent explicit.
2020-02-13 10:16:06 -08:00
Yuanfang Chen 17122ec10a Revert "Revert "Revert "Reland "[Support] make report_fatal_error `abort` instead of `exit`""""
This reverts commit bb51d24330.
2020-02-13 10:08:05 -08:00
Yuanfang Chen bb51d24330 Revert "Revert "Reland "[Support] make report_fatal_error `abort` instead of `exit`"""
This reverts commit 80a34ae311 with fixes.

On bots llvm-clang-x86_64-expensive-checks-ubuntu and
llvm-clang-x86_64-expensive-checks-debian only,
llc returns 0 for these two tests unexpectedly. I tweaked the RUN line a little
bit in the hope that LIT is the culprit since this change is not in the
codepath these tests are testing.
llvm\test\CodeGen\X86\inline-asm-avx-v-constraint-32bit.ll
llvm\test\CodeGen\X86\inline-asm-avx512vl-v-constraint-32bit.ll
2020-02-13 10:02:53 -08:00
Fangrui Song 6c73246179 [ELF] Fix a null pointer dereference when --emit-relocs and --strip-debug are used together
Fixes https://bugs.llvm.org//show_bug.cgi?id=44878

When --strip-debug is specified, .debug* are removed from inputSections
while .rel[a].debug* (incorrectly) remain.

LinkerScript::addOrphanSections() requires the output section of a relocated
InputSectionBase to be created first.

.debug* are not in inputSections ->
output sections .debug* are not created ->
getOutputSectionName(.rel[a].debug*) dereferences a null pointer.

Fix the null pointer dereference by deleting .rel[a].debug* from inputSections as well.

Reviewed By: grimar, nickdesaulniers

Differential Revision: https://reviews.llvm.org/D74510
2020-02-13 08:56:38 -08:00
Peter Smith 29c1361557 [LLD][ELF][ARM] Do not substitute BL/BLX for non STT_FUNC symbols.
Recommit of 0b4a047bfb
(reverted in c29003813a) to incorporate
subsequent fix and add a warning when LLD's interworking behavior has
changed.

D73474 disabled the generation of interworking thunks for branch
relocations to non STT_FUNC symbols. This patch handles the case of BL and
BLX instructions to non STT_FUNC symbols. LLD would normally look at the
state of the caller and the callee and write a BL if the states are the
same and a BLX if the states are different.

This patch disables BL/BLX substitution when the destination symbol does
not have type STT_FUNC. This brings our behavior in line with GNU ld which
may prevent difficult to diagnose runtime errors when switching to lld.

This change does change how LLD handles interworking of symbols that do not
have type STT_FUNC from previous versions including the 10.0 release. This
brings LLD in line with ld.bfd but there may be programs that have not been
linked with ld.bfd that depend on LLD's previous behavior. We emit a warning
when the behavior changes.

A summary of the difference between 10.0 and 11.0 is that for symbols
that do not have a type of STT_FUNC LLD will not change a BL to a BLX or
vice versa. The table below enumerates the changes
| relocation     | STT_FUNC | bit(0) | in  | 10.0- out | 11.0+ out |
| R_ARM_CALL     | no       | 1      | BL  | BLX       | BL        |
| R_ARM_CALL     | no       | 0      | BLX | BL        | BLX       |
| R_ARM_THM_CALL | no       | 1      | BLX | BL        | BLX       |
| R_ARM_THM_CALL | no       | 0      | BL  | BLX       | BL        |

Differential Revision: https://reviews.llvm.org/D73542
2020-02-13 09:40:21 +00:00
Igor Kudrin 2ba4df6c11 [DebugInfo] Fix dumping CIE ID in .eh_frame sections.
We do not keep the actual value of the CIE ID field, because it is
predefined, and use a constant when dumping a CIE record. The issue
was that the predefined value is different for .debug_frame and
.eh_frame sections, but we always printed the one which corresponds
to .debug_frame. The patch fixes that by choosing an appropriate
constant to print.

See the following for more information about .eh_frame sections:
https://refspecs.linuxfoundation.org/LSB_5.0.0/LSB-Core-generic/LSB-Core-generic/ehframechpt.html

Differential Revision: https://reviews.llvm.org/D73627
2020-02-13 15:42:14 +07:00
Fangrui Song 81cebfd008 [ELF][test] Change -o %t to -o /dev/null if the output is not needed 2020-02-12 21:54:50 -08:00
Sterling Augustine a7ecf4c324 Explicitly state the output file.
Summary:
Even though this test is a check for failure, lld still attempts
to open the final output file, which fails when the default "a.out"
file is used and the current directory is read-only. Specifying an
output file works around this problem.

Reviewers: espindola

Subscribers: emaste, MaskRay, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D74523
2020-02-12 21:25:30 -08:00
Fangrui Song 7c426fb1a6 [ELF] Support INSERT [AFTER|BEFORE] for orphan sections
D43468+D44380 added INSERT [AFTER|BEFORE] for non-orphan sections. This patch
makes INSERT work for orphan sections as well.

`SECTIONS {...} INSERT [AFTER|BEFORE] .foo` does not set `hasSectionCommands`, so the result
will be similar to a regular link without a linker script. The differences when `hasSectionCommands` is set include:

* image base is different
* -z noseparate-code/-z noseparate-loadable-segments are unavailable
* some special symbols such as `_end _etext _edata` are not defined

The behavior is similar to GNU ld:
INSERT is not considered an external linker script.

This feature makes the section layout more flexible. It can be used to:

* Place .nv_fatbin before other readonly SHT_PROGBITS sections to mitigate relocation overflows.
* Disturb the layout to expose address sensitive application bugs.

Reviewed By: grimar

Differential Revision: https://reviews.llvm.org/D74375
2020-02-12 08:21:52 -08:00
Fangrui Song b498d99338 [ELF] Start a new PT_LOAD if LMA region is different
GNU ld has a counterintuitive lang_propagate_lma_regions rule.

```
// .foo's LMA region is propagated to .bar because their VMA region is the same,
// and .bar does not have an explicit output section address (addr_tree).
.foo : { *(.foo) } >RAM AT> FLASH
.bar : { *(.bar) } >RAM

// An explicit output section address disables propagation.
.foo : { *(.foo) } >RAM AT> FLASH
.bar . : { *(.bar) } >RAM
```

In both cases, lld thinks .foo's LMA region is propagated and
places .bar in the same PT_LOAD, so lld diverges from GNU ld w.r.t. the
second case (lma-align.test).

This patch changes Writer<ELFT>::createPhdrs to disable propagation
(start a new PT_LOAD). A user of the first case can make linker scripts
portable by explicitly specifying `AT>`. By contrast, there was no
workaround for the old behavior.

This change uncovers another LMA related bug in assignOffsets() where
`ctx->lmaOffset = 0;` was omitted. It caused a spurious "load address
range overlaps" error for at2.test

The new PT_LOAD rule is complex. For convenience, I listed the origins of some subexpressions:

* rL323449: `sec->memRegion == load->firstSec->memRegion`; linkerscript/at3.test
* D43284: `load->lastSec == Out::programHeaders` (don't start a new PT_LOAD after program headers); linkerscript/at4.test
* D58892: `sec != relroEnd` (start a new PT_LOAD after PT_GNU_RELRO)

Reviewed By: psmith

Differential Revision: https://reviews.llvm.org/D74297
2020-02-12 08:20:14 -08:00
Fangrui Song e21b9ca751 [ELF] Respect output section alignment for AT> (non-null lmaRegion)
When lmaRegion is non-null, respect `sec->alignment`
This rule is analogous to `switchTo(sec)` which advances sh_addr (VMA).

This fixes the p_paddr misalignment issue as reported by
https://android-review.googlesource.com/c/trusty/external/trusted-firmware-a/+/1230058

Note, `sec->alignment` is the maximum of ALIGN and input section alignments. We may overalign LMA than GNU ld.

linkerscript/align-lma.s has a FIXME that demonstrates another bug:
`.bss ... >RAM` should be placed in a different PT_LOAD (GNU ld
behavior) because its lmaRegion (nullptr) is different from the previous
section's lmaRegion (ROM).

Reviewed By: psmith

Differential Revision: https://reviews.llvm.org/D74286
2020-02-12 08:19:42 -08:00
Jordan Rupprecht 60a8a504f1 [llvm-objdump] Print file format in lowercase to match GNU output.
Summary:
GNU objdump prints the file format in lowercase, e.g. `elf64-x86-64`. llvm-objdump prints `ELF64-x86-64` right now, even though piping that into llvm-objcopy refuses that as a valid arch to use.

As an example of a problem this causes, see: https://github.com/ClangBuiltLinux/linux/issues/779

Reviewers: MaskRay, jhenderson, alexshap

Reviewed By: MaskRay

Subscribers: tpimh, sbc100, grimar, jvesely, nhaehnle, kerbowa, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D74433
2020-02-12 08:17:01 -08:00
James Henderson 1da62b51a5 [DebugInfo] Print version in error message in decimal
Also remove some test duplication and add a test case that shows the
maximum version is rejected (this also shows that the value in the error
message is actually in decimal, and not just missing an 0x prefix).

Reviewed by: dblaikie

Differential Revision: https://reviews.llvm.org/D74403
2020-02-12 14:49:22 +00:00
Yuanfang Chen 80a34ae311 Revert "Reland "[Support] make report_fatal_error `abort` instead of `exit`""
This reverts commit rGcd5b308b828e, rGcd5b308b828e, rG8cedf0e2994c.

There are issues to be investigated for polly bots and bots turning on
EXPENSIVE_CHECKS.
2020-02-11 20:41:53 -08:00
Yuanfang Chen 8cedf0e299 Reland "[Support] make report_fatal_error `abort` instead of `exit`"
Summary:
Reland D67847 after D73742 is committed. Replace `sys::Process::Exit(1)`
with `abort` in `report_fatal_error`.

After this patch, for tools turning on `CrashRecoveryContext`,
crash handler installed by `CrashRecoveryContext` is called unless
they installed a non-returning handler using `llvm::install_fatal_error_handler`
like `cc1_main` currently does.

Reviewers: rnk, MaskRay, aganea, hans, espindola, jhenderson

Subscribers: jholewinski, qcolombet, dschuff, jyknight, emaste, sdardis, nemanjai, jvesely, nhaehnle, sbc100, jgravelle-google, hiraditya, aheejin, kbarton, fedor.sergeev, asb, rbar, johnrusso, simoncook, sabuasal, niosHD, jrtc27, zzheng, edward-jones, atanasyan, steven_wu, rogfer01, MartinMosbeck, brucehoult, the_o, dexonsmith, PkmX, rupprecht, jocewei, jsji, Jim, dmgreen, lenary, s.egerton, pzheng, sameer.abuasal, apazos, luismarques, kerbowa, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D74456
2020-02-11 18:20:40 -08:00
Sam Clegg b062fe1816 [lld][WebAssembly] Fail if bitcode objects are pulled in after LTO
This can happen if lto::LTO::getRuntimeLibcallSymbols doesn't return
an complete/accurate list of libcalls.  In this case new bitcode
object can be linked in after LTO.

For example the WebAssembly backend currently calls:
  setLibcallName(RTLIB::FPROUND_F32_F16, "__truncsfhf2");

But `__truncsfhf2` is not part of `getRuntimeLibcallSymbols` so if
this symbol is generated during LTO the link will currently fail.

Without this change the linker crashes because the bitcode symbol
makes it all the way to the output phase.

See: https://bugs.llvm.org/show_bug.cgi?id=44353

Differential Revision: https://reviews.llvm.org/D71632
2020-02-11 17:36:15 -08:00
Fangrui Song 9f854c0489 [ELF][RISCV] Add R_RISCV_IRELATIVE
https://github.com/riscv/riscv-elf-psabi-doc/pull/131 assigned 58 to R_RISCV_IRELATIVE.

Differential Revision: https://reviews.llvm.org/D74022
2020-02-10 20:22:39 -08:00
Fangrui Song 1732f50ee0 [ELF][test] Use llvm-readelf -l instead of llvm-readobj -l for some memory region tests 2020-02-08 22:45:00 -08:00
Fangrui Song 5f38040359 [ELF] Simplify parsing of version dependency. NFC 2020-02-08 14:10:29 -08:00
Fangrui Song f08099b9c2 [ELF][ARM][test] Keep arm-thumb-interwork-shared.s
The revert of D73542 (c29003813a) deleted
the newly added tests to arm-thumb-interwork-shared.s . We should keep
them.
2020-02-07 09:48:48 -08:00
Nico Weber c29003813a Revert "[LLD][ELF][ARM] Do not substitute BL/BLX for non STT_FUNC symbols."
There are still problems after the fix in
"[ELF][ARM] Fix regression of BL->BLX substitution after D73542"
so let's revert to get trunk back to green while we investigate.
See https://reviews.llvm.org/D73542

This reverts commit 5461fa2b1f.
This reverts commit 0b4a047bfb.
2020-02-07 08:55:52 -05:00
Russell Gallop e7cb374433 [LLD][ELF] Add time-trace to ELF LLD
This adds some of LLD specific scopes and picks up optimisation scopes
via LTO/ThinLTO. Makes use of TimeProfiler multi-thread support added in
77e6bb3c.

Differential Revision: https://reviews.llvm.org/D71060
2020-02-06 12:14:13 +00:00
Fangrui Song 7ddd130705 Fix lld test after D74034 2020-02-06 01:14:47 -08:00
Fangrui Song 5461fa2b1f [ELF][ARM] Fix regression of BL->BLX substitution after D73542
D73542 made a typo (`rel.type == R_PLT_PC`; should be `rel.expr`) and introduced a regression:
BL->BLX substitution was disabled when the target symbol is preemptible
(expr is R_PLT_PC).

The two added bl instructions in arm-thumb-interwork-shared.s check that
we patch BL to BLX.

Fixes https://bugs.chromium.org/p/chromium/issues/detail?id=1047531
2020-02-05 14:09:14 -08:00
Fangrui Song 77519b60d9 [test] yaml2obj -docnum => --docnum= 2020-02-05 10:25:04 -08:00
Fangrui Song da1973a241 [ELF][Mips] Drop an unneeded config->relocatable check 2020-01-31 21:00:28 -08:00
Jonas Devlieghere 3e24242a7d [lld] Replace SmallStr.str().str() with std::string conversion operator.
Use the std::string conversion operator introduced in
d7049213d0.
2020-01-29 21:30:21 -08:00
Fangrui Song 4a4ce14eb2 [ELF] Mention symbol name in reportRangeError()
For an out-of-range relocation referencing a non-local symbol, report the symbol name and the object file that defines the symbol. As an example:
```
t.o:(function func: .text.func+0x3): relocation R_X86_64_32S out of range: -281474974609120 is not in [-2147483648, 2147483647]
```
=>
```
t.o:(function func: .text.func+0x3): relocation R_X86_64_32S out of range: -281474974609120 is not in [-2147483648, 2147483647]; references func
>>> defined in t1.o
```

Reviewed By: grimar

Differential Revision: https://reviews.llvm.org/D73518
2020-01-29 09:38:25 -08:00
Peter Smith 0b4a047bfb [LLD][ELF][ARM] Do not substitute BL/BLX for non STT_FUNC symbols.
D73474 disabled the generation of interworking thunks for branch
relocations to non STT_FUNC symbols. This patch handles the case of BL and
BLX instructions to non STT_FUNC symbols. LLD would normally look at the
state of the caller and the callee and write a BL if the states are the
same and a BLX if the states are different.

This patch disables BL/BLX substitution when the destination symbol does
not have type STT_FUNC. This brings our behavior in line with GNU ld which
may prevent difficult to diagnose runtime errors when switching to lld.

Differential Revision: https://reviews.llvm.org/D73542
2020-01-29 11:42:25 +00:00
James Henderson 7116e431c0 [DebugInfo] Make most debug line prologue errors non-fatal to parsing
Many of the debug line prologue errors are not inherently fatal. In most
cases, we can make reasonable assumptions and carry on. This patch does
exactly that. In the case of length problems, the approach of "assume
stated length is correct" is taken which means the offset might need
adjusting.

This is a relanding of b94191fe, fixing an LLD test and the LLDB build.

Reviewed by: dblaikie, labath

Differential Revision: https://reviews.llvm.org/D72158
2020-01-29 10:23:41 +00:00
Benjamin Kramer adcd026838 Make llvm::StringRef to std::string conversions explicit.
This is how it should've been and brings it more in line with
std::string_view. There should be no functional change here.

This is mostly mechanical from a custom clang-tidy check, with a lot of
manual fixups. It uncovers a lot of minor inefficiencies.

This doesn't actually modify StringRef yet, I'll do that in a follow-up.
2020-01-28 23:25:25 +01:00
Fangrui Song e11b709b19 [ELF][PPC32] Support --emit-relocs link of R_PPC_PLTREL24
Similar to R_MIPS_GPREL16 and R_MIPS_GPREL32 (D45972).

If the addend of an R_PPC_PLTREL24 is >= 0x8000, it indicates that r30
is relative to the input section .got2.

```
addis 30, 30, .got2+0x8000-.L1$pb@ha
addi 30, 30, .got2+0x8000-.L1$pb@l
...
bl foo+0x8000@PLT
```

After linking, the relocation will be relative to the output section .got2.
To compensate for the shift `address(input section .got2) - address(output section .got2) = ppc32Got2OutSecOff`, adjust by `ppc32Got2OutSecOff`:

```
addis 30, 30, .got2+0x8000-.L1+ppc32Got2OutSecOff$pb@ha
addi 30, 30, .got2+0x8000-.L1+ppc32Got2OutSecOff$pb@ha$pb@l
...
bl foo+0x8000+ppc32Got2OutSecOff@PLT
```

This rule applys to a relocatable link or a non-relocatable link with --emit-relocs.

Reviewed By: Bdragon28

Differential Revision: https://reviews.llvm.org/D73532
2020-01-28 11:04:04 -08:00
Andrew Ng de2dfc8b20 [LLD] Avoid exiting with a locked mutex NFC
In ErrorHandler::error(), rearrange code to avoid calling exitLld with
the mutex locked. Acquire mutex lock when flushing the output streams in
exitLld.

Differential Revision: https://reviews.llvm.org/D73281
2020-01-28 16:44:44 +00:00
Peter Smith 4f38ab250f [LLD][ELF][ARM] Do not insert interworking thunks for non STT_FUNC symbols
ELF for the ARM architecture requires linkers to provide
interworking for symbols that are of type STT_FUNC. Interworking for
other symbols must be encoded directly in the object file. LLD was always
providing interworking, regardless of the symbol type, this breaks some
programs that have branches from Thumb state targeting STT_NOTYPE symbols
that have bit 0 clear, but they are in fact internal labels in a Thumb
function. LLD treats these symbols as ARM and inserts a transition to Arm.

This fixes the problem for in range branches, R_ARM_JUMP24,
R_ARM_THM_JUMP24 and R_ARM_THM_JUMP19. This is expected to be the vast
majority of problem cases as branching to an internal label close to the
function.

There is at least one follow up patch required.
- R_ARM_CALL and R_ARM_THM_CALL may do interworking via BL/BLX
  substitution.

In theory range-extension thunks can be altered to not change state when
the symbol type is not STT_FUNC. I will need to check with ld.bfd to see if
this is the case in practice.

Fixes (part of) https://github.com/ClangBuiltLinux/linux/issues/773

Differential Revision: https://reviews.llvm.org/D73474
2020-01-28 11:54:18 +00:00
Peter Smith 3238b03c19 [LLD][ELF][ARM] clang-format function signature [NFC]
ARM::needsThunk had gone over 80 characters, run clang-format over it to
prevent it wrapping.
2020-01-28 11:54:18 +00:00
Teresa Johnson 2f63d549f1 Restore "[LTO/WPD] Enable aggressive WPD under LTO option"
This restores 59733525d3 (D71913), along
with bot fix 19c76989bb.

The bot failure should be fixed by D73418, committed as
af954e441a.

I also added a fix for non-x86 bot failures by requiring x86 in new test
lld/test/ELF/lto/devirt_vcall_vis_public.ll.
2020-01-27 07:55:05 -08:00
Fangrui Song 70389be7a0 [ELF][PPC32] Support range extension thunks with addends
* Generalize the code added in D70637 and D70937. We should eventually remove the EM_MIPS special case.
* Handle R_PPC_LOCAL24PC the same way as R_PPC_REL24.

Reviewed By: Bdragon28

Differential Revision: https://reviews.llvm.org/D73424
2020-01-25 22:32:42 -08:00
Fangrui Song 837e8a9c0c [ELF][PPC32] Support canonical PLT
-fno-pie produces a pair of non-GOT-non-PLT relocations R_PPC_ADDR16_{HA,LO} (R_ABS) referencing external
functions.

```
lis 3, func@ha
la 3, func@l(3)
```

In a -no-pie/-pie link, if func is not defined in the executable, a canonical PLT entry (st_value>0, st_shndx=0) will be needed.
References to func in shared objects will be resolved to this address.
-fno-pie -pie should fail with "can't create dynamic relocation ... against ...", so we just need to think about -no-pie.

On x86, the PLT entry passes the JMP_SLOT offset to the rtld PLT resolver.
On x86-64: the PLT entry passes the JUMP_SLOT index to the rtld PLT resolver.
On ARM/AArch64: the PLT entry passes &.got.plt[n]. The PLT header passes &.got.plt[fixed-index]. The rtld PLT resolver can compute the JUMP_SLOT index from the two addresses.

For these targets, the canonical PLT entry can just reuse the regular PLT entry (in PltSection).

On PPC32: PltSection (.glink) consists of `b PLTresolve` instructions and `PLTresolve`. The rtld PLT resolver depends on r11 having been set up to the .plt (GotPltSection) entry.
On PPC64 ELFv2: PltSection (.glink) consists of `__glink_PLTresolve` and `bl __glink_PLTresolve`. The rtld PLT resolver depends on r12 having been set up to the .plt (GotPltSection) entry.

We cannot reuse a `b PLTresolve`/`bl __glink_PLTresolve` in PltSection as a canonical PLT entry. PPC64 ELFv2 avoids the problem by using TOC for any external reference, even in non-pic code, so the canonical PLT entry scenario should not happen in the first place.
For PPC32, we have to create a PLT call stub as the canonical PLT entry. The code sequence sets up r11.

Reviewed By: Bdragon28

Differential Revision: https://reviews.llvm.org/D73399
2020-01-25 17:56:37 -08:00
Fangrui Song deb5819d62 [ELF] Rename relocateOne() to relocate() and pass `Relocation` to it
Symbol information can be used to improve out-of-range/misalignment diagnostics.
It also helps R_ARM_CALL/R_ARM_THM_CALL which has different behaviors with different symbol types.

There are many (67) relocateOne() call sites used in thunks, {Arm,AArch64}errata, PLT, etc.
Rename them to `relocateNoSym()` to be clearer that there is no symbol information.

Reviewed By: grimar, peter.smith

Differential Revision: https://reviews.llvm.org/D73254
2020-01-25 12:00:18 -08:00
Fangrui Song f1dab29908 [ELF][PowerPC] Support R_PPC_COPY and R_PPC64_COPY
Reviewed By: Bdragon28, jhenderson, grimar, sfertile

Differential Revision: https://reviews.llvm.org/D73255
2020-01-24 09:06:20 -08:00
Teresa Johnson 90e630a95e Revert "[LTO/WPD] Enable aggressive WPD under LTO option"
This reverts commit 59733525d3.

There is a windows sanitizer bot failure in one of the cfi tests
that I will need some time to figure out:
http://lab.llvm.org:8011/builders/sanitizer-windows/builds/57155/steps/stage%201%20check/logs/stdio
2020-01-23 17:29:24 -08:00
Teresa Johnson 59733525d3 [LTO/WPD] Enable aggressive WPD under LTO option
Summary:
Third part in series to support Safe Whole Program Devirtualization
Enablement, see RFC here:
http://lists.llvm.org/pipermail/llvm-dev/2019-December/137543.html

This patch adds type test metadata under -fwhole-program-vtables,
even for classes without hidden visibility. It then changes WPD to skip
devirtualization for a virtual function call when any of the compatible
vtables has public vcall visibility.

Additionally, internal LLVM options as well as lld and gold-plugin
options are added which enable upgrading all public vcall visibility
to linkage unit (hidden) visibility during LTO. This enables the more
aggressive WPD to kick in based on LTO time knowledge of the visibility
guarantees.

Support was added to all flavors of LTO WPD (regular, hybrid and
index-only), and to both the new and old LTO APIs.

Unfortunately it was not simple to split the first and second parts of
this part of the change (the unconditional emission of type tests and
the upgrading of the vcall visiblity) as I needed a way to upgrade the
public visibility on legacy WPD llvm assembly tests that don't include
linkage unit vcall visibility specifiers, to avoid a lot of test churn.

I also added a mechanism to LowerTypeTests that allows dropping type
test assume sequences we now aggressively insert when we invoke
distributed ThinLTO backends with null indexes, which is used in testing
mode, and which doesn't invoke the normal ThinLTO backend pipeline.

Depends on D71907 and D71911.

Reviewers: pcc, evgeny777, steven_wu, espindola

Subscribers: emaste, Prazek, inglorion, arichardson, hiraditya, MaskRay, dexonsmith, dang, davidxl, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D71913
2020-01-23 16:09:44 -08:00
Fangrui Song 0fbf28f7aa [ELF] --no-dynamic-linker: don't emit undefined weak symbols to .dynsym
I felt really sad to push this commit for my selfish purpose to make
glibc -static-pie build with lld. Some code constructs in glibc require
R_X86_64_GOTPCREL/R_X86_64_REX_GOTPCRELX referencing undefined weak to
be resolved to a GOT entry not relocated by R_X86_64_GLOB_DAT (GNU ld
behavior), e.g.

csu/libc-start.c
  if (__pthread_initialize_minimal != NULL)
    __pthread_initialize_minimal ();

elf/dl-object.c
  void
  _dl_add_to_namespace_list (struct link_map *new, Lmid_t nsid)
  {
    /* We modify the list of loaded objects.  */
    __rtld_lock_lock_recursive (GL(dl_load_write_lock));

Emitting a GLOB_DAT will make the address equal &__ehdr_start (true
value) and cause elf/ldconfig to segfault. glibc really should move away
from weak references, which do not have defined semantics.

Temporarily special case --no-dynamic-linker.
2020-01-23 12:25:15 -08:00
Reid Kleckner e5caa156b4 [PDB] Simplify API for making section map, NFC
Prevents API misuse described in PR44495
2020-01-23 12:15:21 -08:00
Fangrui Song 1e57038bf2 [ELF] Pass `Relocation` to relaxGot and relaxTls{GdToIe,GdToLe,LdToLe,IeToLe}
These functions call relocateOne(). This patch is a prerequisite for
making relocateOne() aware of `Symbol` (D73254).

Reviewed By: grimar, nickdesaulniers

Differential Revision: https://reviews.llvm.org/D73250
2020-01-23 10:39:25 -08:00
Martin Storsjö e6b0ce70bd [LLD] [COFF] Silence a GCC warning about an unused variable. NFC. 2020-01-23 13:23:56 +02:00
Markus Böck 9dbc1ab232 [LLD][COFF] Enable linking of __declspec(selectany) symbols from Clang and GCC
When annotating a symbol with __declspec(selectany), Clang assigns it
comdat 2 while GCC assigns it comdat 3. This patch enables two object
files that contain a __declspec(selectany) symbol, one created by gcc
and the other by clang, to be linked together instead of issuing a
duplicate symbol error.

Differential Revision: https://reviews.llvm.org/D73139
2020-01-23 10:55:27 +02:00
James Clarke ddfe8751b1 [test] Fix lld/test/ELF/riscv-pcrel-hilo-error.s after D73211 2020-01-23 02:30:10 +00:00
Thomas Preud'homme c42fe24754 [lld/ELF] PR44498: Support input filename in double quote
Summary:
Linker scripts allow filenames to be put in double quotes to prevent
characters in filenames that are part of the linker script syntax from
having their special meaning. Case in point the * wildcard character.

Availability of double quoting filenames also allows to fix a failure in
ELF/linkerscript/filename-spec.s when the path contain a @ which the
lexer consider as a special characters and thus break up a filename
containing it. This may happens under Jenkins which createspath such as
pipeline@2.

To avoid the need for escaping GlobPattern metacharacters in filename
in double quotes, GlobPattern::create is augmented with a new parameter
to request literal matching instead of relying on the presence of a
wildcard character in the pattern.

Reviewers: jhenderson, MaskRay, evgeny777, espindola, alexshap

Reviewed By: MaskRay

Subscribers: peter.smith, grimar, ruiu, emaste, arichardson, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D72517
2020-01-22 12:03:10 +00:00
Peter Smith e727f39ec0 [LLD][ELF][ARM] Don't apply --fix-cortex-a8 to relocatable links.
The --fix-cortex-a8 is sensitive to alignment and the precise destination
of branch instructions. These are not knowable at relocatable link time. We
follow GNU ld and the --fix-cortex-a53-843419 (D72968) by not patching the
code when there is a relocatable link.

Differential Revision: https://reviews.llvm.org/D73100
2020-01-22 11:03:40 +00:00
Sid Manning 6b9a5e6f05 [lld][Hexagon] Add General Dynamic relocations (GD)
Differential revision: https://reviews.llvm.org/D72522
2020-01-21 14:10:03 -06:00
Andrew Ng 4e8116f469 [ELF] Refactor uses of getInputSections to improve efficiency NFC
Add new method getFirstInputSection and use instead of getInputSections
where appropriate to avoid creation of an unneeded vector of input
sections.

Differential Revision: https://reviews.llvm.org/D73047
2020-01-21 12:27:52 +00:00
Peter Smith dbd0ad3366 [LLD][ELF] Add support for INPUT_SECTION_FLAGS
The INPUT_SECTION_FLAGS linker script command is used to constrain the
section pattern matching to sections that match certain combinations of
flags.

There are two ways to express the constraint.
withFlags: Section must have these flags.
withoutFlags: Section must not have these flags.

The syntax of the command is:
INPUT_SECTION_FLAGS '(' sect_flag_list ')'
sect_flag_list: NAME
| sect_flag_list '&' NAME

Where NAME matches a section flag name such as SHF_EXECINSTR, or the
integer value of a section flag. If the first character of NAME is ! then
it means must not contain flag.

We do not support the rare case of { INPUT_SECTION_FLAGS(flags) filespec }
where filespec has no input section description like (.text).

As an example from the ld man page:
SECTIONS {
  .text : { INPUT_SECTION_FLAGS (SHF_MERGE & SHF_STRINGS) *(.text) }
  .text2 :  { INPUT_SECTION_FLAGS (!SHF_WRITE) *(.text) }
}
.text will match sections called .text that have both the SHF_MERGE and
SHF_STRINGS flag.
.text2 will match sections called .text that don't have the SHF_WRITE flag.

The flag names accepted are the generic to all targets and SHF_ARM_PURECODE
as it is very useful to filter all the pure code sections into a single
program header that can be marked execute never.

fixes PR44265

Differential Revision: https://reviews.llvm.org/D72756
2020-01-21 10:05:26 +00:00
Igor Kudrin 6b4f86f65f Reapply: [MachO] Add a test for detecting reserved unit length.
The test in the origin patch did not create a __debug_str section.
An UBSan check triggered when the corresponding pointer was dereferenced.

Differential Revision: https://reviews.llvm.org/D72695

This reapplies fcc08aa835
which was reverted in b16f82ad3b.
2020-01-21 16:59:44 +07:00
Mitch Phillips b16f82ad3b Revert "[MachO] Add a test for detecting reserved unit length."
This change broke the UBSan buildbots. More information available in the
original Phabricator review: https://reviews.llvm.org/D72695

This reverts commit fcc08aa835.
2020-01-20 22:39:24 -08:00
James Clarke d1da63664f [lld][RISCV] Print error when encountering R_RISCV_ALIGN
Summary:
Unlike R_RISCV_RELAX, which is a linker hint, R_RISCV_ALIGN requires the
support of the linker even when ignoring all R_RISCV_RELAX relocations.
This is because the compiler emits as many NOPs as may be required for
the requested alignment, more than may be required pre-relaxation, to
allow for the target becoming more unaligned after relaxing earlier
sequences. This means that the target is often not initially aligned in
the object files, and so the R_RISCV_ALIGN relocations cannot just be
ignored. Since we do not support linker relaxation, we must turn these
into errors.

Reviewers: ruiu, MaskRay, espindola

Reviewed By: MaskRay

Subscribers: grimar, Jim, emaste, arichardson, asb, rbar, johnrusso, simoncook, sabuasal, niosHD, kito-cheng, shiva0217, zzheng, edward-jones, rogfer01, MartinMosbeck, brucehoult, the_o, rkruppe, PkmX, jocewei, psnobl, benna, lenary, s.egerton, pzheng, sameer.abuasal, apazos, luismarques, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D71820
2020-01-21 02:49:45 +00:00
Eli Friedman c81fe34718 [lld][ELF] Don't apply --fix-cortex-a53-843419 to relocatable links.
The code doesn't apply the fix correctly to relocatable links. I could
try to fix the code that applies the fix, but it's pointless: we don't
actually know what the offset will be in the final executable. So just
ignore the flag for relocatable links.

Issue discovered building Android.

Differential Revision: https://reviews.llvm.org/D72968
2020-01-20 15:27:41 -08:00
Derek Schuff ff171acf84 [WebAssembly] Track frame registers through VReg and local allocation
This change has 2 components:

Target-independent: add a method getDwarfFrameBase to TargetFrameLowering. It
describes how the Dwarf frame base will be encoded.  That can be a register (the
default), the CFA (which replaces NVPTX-specific logic in DwarfCompileUnit), or
a DW_OP_WASM_location descriptr.

WebAssembly: Allow WebAssemblyFunctionInfo::getFrameRegister to return the
correct virtual register instead of FP32/SP32 after WebAssemblyReplacePhysRegs
has run.  Make WebAssemblyExplicitLocals store the local it allocates for the
frame register. Use this local information to implement getDwarfFrameBase

The result is that the DW_AT_frame_base attribute is correctly encoded for each
subprogram, and each param and local variable has a correct DW_AT_location that
uses DW_OP_fbreg to refer to the frame base.

This is a reland of rG3a05c3969c18 with fixes for the expensive-checks
and Windows builds

Differential Revision: https://reviews.llvm.org/D71681
2020-01-17 17:23:56 -08:00
Fangrui Song 6ab89c3c5d [ELF] Allow R_PLT_PC (R_PC) to a hidden undefined weak symbol
This essentially reverts b841e119d7.

Such code construct can be used in the following way:

  // glibc/stdlib/exit.c
  // clang -fuse-ld=lld => succeeded
  // clang -fuse-ld=lld -fpie -pie => relocation R_PLT_PC cannot refer to absolute symbol
  __attribute__((weak, visibility("hidden"))) extern void __call_tls_dtors();
  void __run_exit_handlers() {
    if (__call_tls_dtors)
        __call_tls_dtors();
  }

Since we allow R_PLT_PC in -no-pie mode, it makes sense to allow it in
-pie mode as well.

Reviewed By: pcc

Differential Revision: https://reviews.llvm.org/D72943
2020-01-17 13:06:42 -08:00
Fangrui Song 08f2b67d03 [test] Fix test/ELF/lto/thinlto-obj-path.ll after D52810 2020-01-17 10:13:21 -08:00
Peter Smith 01ad4c8384 [LLD][ELF][ARM][AArch64] Only round up ThunkSection Size when large OS.
In D71281 a fix was put in to round up the size of a ThunkSection to the
nearest 4KiB when performing errata patching. This fixed a problem with a
very large instrumented program that had thunks and patches mutually
trigger each other. Unfortunately it triggers an assertion failure in an
AArch64 allyesconfig build of the kernel. There is a specific assertion
preventing an InputSectionDescription being larger than 4KiB. This will
always trigger if there is at least one Thunk needed in that
InputSectionDescription, which is possible for an allyesconfig build.

Abstractly the problem case is:
.text : {
          *(.text) ;
          ...
          . = ALIGN(SZ_4K);
          __idmap_text_start = .;
          *(.idmap.text)
          __idmap_text_end = .;
          ...
        }
The assertion checks that __idmap_text_end - __idmap_start is < 4 KiB.
Note that there is more than one InputSectionDescription in the
OutputSection so we can't just restrict the fix to OutputSections smaller
than 4 KiB.

The fix presented here limits the D71281 to InputSectionDescriptions that
meet the following conditions:
1.) The OutputSection is bigger than the thunkSectionSpacing so adding
thunks will affect the addresses of following code.
2.) The InputSectionDescription is larger than 4 KiB. This will prevent
any assertion failures that an InputSectionDescription is < 4 KiB
in size.

We do this at ThunkSection creation time as at this point we know that
the addresses are stable and up to date prior to adding the thunks as
assignAddresses() will have been called immediately prior to thunk
generation.

The fix reverts the two tests affected by D71281 to their original state
as they no longer need the 4KiB size roundup. I've added simpler tests to
check for D71281 when the OutputSection size is larger than the ThunkSection
spacing.

Fixes https://github.com/ClangBuiltLinux/linux/issues/812

Differential Revision: https://reviews.llvm.org/D72344
2020-01-17 10:47:21 +00:00
Nico Weber fb5fafb23c Make LLVM_APPEND_VC_REV=OFF affect clang, lld, and lldb as well.
When LLVM_APPEND_VC_REV=OFF is set, the current git hash is no
longer embedded into binaries (mostly for --version output).
Without it, most binaries need to relink after every single
commit, even if they didn't change otherwise (due to, say,
a documentation-only commit).

LLVM_APPEND_VC_REV is ON by default, so this doesn't change the
default behavior of anything.

With this, all clients of GenerateVersionFromVCS.cmake honor
LLVM_APPEND_VC_REV.

Differential Revision: https://reviews.llvm.org/D72855
2020-01-16 19:04:08 -05:00
Sam Clegg 51b521c07a [lld][WebAssembly] Use a more meaningful name for stub functions
When we generate these stub functions on signature mismatches give
them a more meaningful name so that when people see this in stack
traces is gives a clue as the what is going on.

See: https://github.com/emscripten-core/emscripten/issues/10226

Differential Revision: https://reviews.llvm.org/D72881
2020-01-16 14:55:37 -08:00
Derek Schuff 80906d9d16 Revert "[WebAssembly] Track frame registers through VReg and local allocation"
This reverts commit 3a05c3969c.
It breaks under expensive-checks and on Windows
2020-01-16 14:38:00 -08:00
Derek Schuff 3a05c3969c [WebAssembly] Track frame registers through VReg and local allocation
This change has 2 components:

Target-independent: add a method getDwarfFrameBase to TargetFrameLowering. It
describes how the Dwarf frame base will be encoded.  That can be a register (the
default), the CFA (which replaces NVPTX-specific logic in DwarfCompileUnit), or
a DW_OP_WASM_location descriptr.

WebAssembly: Allow WebAssemblyFunctionInfo::getFrameRegister to return the
correct virtual register instead of FP32/SP32 after WebAssemblyReplacePhysRegs
has run.  Make WebAssemblyExplicitLocals store the local it allocates for the
frame register. Use this local information to implement getDwarfFrameBase

The result is that the DW_AT_frame_base attribute is correctly encoded for each
subprogram, and each param and local variable has a correct DW_AT_location that
uses DW_OP_fbreg to refer to the frame base.

Differential Revision: https://reviews.llvm.org/D71681
2020-01-16 13:51:17 -08:00
Fangrui Song 2d7a8cf904 [ELF] -r: don't create .interp
`{clang,gcc} -nostdlib -r a.c` passes --dynamic-linker to the linker,
and the expected behavior is to ignore it.

If .interp is kept in the relocatable object file, a final link will get
PT_INTERP even if --dynamic-linker is not specified. glibc ld.so expects
to see PT_DYNAMIC and the executable will likely fail to run.

Ignore --dynamic-linker in -r mode as well as -shared.
2020-01-16 12:14:32 -08:00
Fangrui Song 870094decf [ELF] Decrease alignment of ThunkSection on 64-bit targets from 8 to 4
ThunkSection contains 4-byte instructions on all targets that use
thunks. Thunks should not be used in any performance sensitive places,
and locality/cache line/instruction fetching arguments should not apply.

We use 16 bytes as preferred function alignments for modern PowerPC cores.
In any case, 8 is not optimal.

Differential Revision: https://reviews.llvm.org/D72819
2020-01-16 10:36:33 -08:00
Nico Weber 4f5c65a5c8 try to unbreak build after 4b6d9ac392 2020-01-16 10:12:35 -05:00
Nico Weber 4b6d9ac392 Make lld cmake not compute commit revision twice
r354605 moved LLD to the unified revision handling introduced in
rL353268 / r352729 and removed uses of LLD_REPOSITORY_STRING and
LLD_REVISION_STRING.

After this change, we no longer compute the (now-unused) values
of these two variables.

Since this removes the only use of llvm/utils/GetRepositoryPath,
remove that too (it's redundant with the system added in r354605).

While here, also remove LLD_VERSION_MAJOR and LLD_VERSION_MINOR.
Their uses were removed in r285163.

Also remove LLD_VERSION from Version.inc which as far as I can
tell has been unused since the file was added in r219277.

No behavior change.

Differential Revision: https://reviews.llvm.org/D72803
2020-01-16 09:55:36 -05:00
Andrew Ng d36b2649e5 [ELF] Optimization to LinkerScript::computeInputSections NFC
Moved the section name check ahead of any filename matching or
exclusion. Firstly, this reduces the need to retrieve the filename and
secondly, reduces the amount of potentially expensive filename pattern
matching if such rules are present in the linker script.

The impact of this change is particularly significant when linking
objects built with -ffunction-sections and -fstack-size-section, using a
linker script that includes non-trivial filename patterns. In a number
of such cases, the link time is halved.

Differential Revision: https://reviews.llvm.org/D72775
2020-01-16 13:56:02 +00:00
Yuanfang Chen 6e24c6037f Revert "[Support] make report_fatal_error `abort` instead of `exit`"
This reverts commit 647c3f4e47.

Got bots failure from sanitizer-windows and maybe others.
2020-01-15 17:52:25 -08:00
Yuanfang Chen 647c3f4e47 [Support] make report_fatal_error `abort` instead of `exit`
Summary:
This patch could be treated as a rebase of D33960. It also fixes PR35547.
A fix for `llvm/test/Other/close-stderr.ll` is proposed in D68164. Seems
the consensus is that the test is passing by chance and I'm not
sure how important it is for us. So it is removed like in D33960 for now.
The rest of the test fixes are just adding `--crash` flag to `not` tool.

** The reason it fixes PR35547 is

`exit` does cleanup including calling class destructor whereas `abort`
does not do any cleanup. In multithreading environment such as ThinLTO or JIT,
threads may share states which mostly are ManagedStatic<>. If faulting thread
tearing down a class when another thread is using it, there are chances of
memory corruption. This is bad 1. It will stop error reporting like pretty
stack printer; 2. The memory corruption is distracting and nondeterministic in
terms of error message, and corruption type (depending one the timing, it
could be double free, heap free after use, etc.).

Reviewers: rnk, chandlerc, zturner, sepavloff, MaskRay, espindola

Reviewed By: rnk, MaskRay

Subscribers: wuzish, jholewinski, qcolombet, dschuff, jyknight, emaste, sdardis, nemanjai, jvesely, nhaehnle, sbc100, arichardson, jgravelle-google, aheejin, kbarton, fedor.sergeev, asb, rbar, johnrusso, simoncook, apazos, sabuasal, niosHD, jrtc27, zzheng, edward-jones, atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, PkmX, jocewei, jsji, lenary, s.egerton, pzheng, cfe-commits, MaskRay, filcab, davide, MatzeB, mehdi_amini, hiraditya, steven_wu, dexonsmith, rupprecht, seiya, llvm-commits

Tags: #llvm, #clang

Differential Revision: https://reviews.llvm.org/D67847
2020-01-15 17:05:13 -08:00
Reid Kleckner 8045a8a7f1 [COFF] Warn that LLD does not support /PDBSTRIPPED:
Doesn't really fix PR44491, but it avoids treating it as an input.
2020-01-15 15:11:19 -08:00
Alex Richardson 441410be47 [ELF] Avoid false-positive assert in getErrPlace()
This assertion was added as part of D70659 but did not account for .bss
input sections. I noticed that this assert was incorrectly triggering
while building FreeBSD for MIPS64. Fixed by relaxing the assert to also
account for SHT_NOBITS input sections and adjust the test
mips-jalr-non-function.s to link a file with a .bss section first.

Reviewed By: MaskRay, grimar
Differential Revision: https://reviews.llvm.org/D72567
2020-01-15 14:32:25 +00:00
Hans Wennborg 5852475e2c Bump the trunk major version to 11
and clear the release notes.
2020-01-15 13:38:01 +01:00
Igor Kudrin fcc08aa835 [MachO] Add a test for detecting reserved unit length.
This is a follow-up for D71546 to add a corresponding unit test.

Differential Revision: https://reviews.llvm.org/D72695
2020-01-15 16:55:11 +07:00
Fangrui Song bec1b55c64 [ELF] Delete the RelExpr member R_HINT. NFC
R_HINT is ignored like R_NONE. There are no strong reasons to keep
R_HINT. The largest RelExpr member R_RISCV_PC_INDIRECT is 60 now.

Differential Revision: https://reviews.llvm.org/D71822
2020-01-14 10:56:53 -08:00
Fangrui Song 40c5bd4212 [ELF] --exclude-libs: don't assign VER_NDX_LOCAL to undefined symbols
Suggested by Peter Collingbourne.

Non-VER_NDX_GLOBAL versions should not be assigned to defined symbols. --exclude-libs violates this and can cause a spurious error "cannot refer to absolute symbol" after D71795.

excludeLibs incorrectly assigns VER_NDX_LOCAL to an undefined weak symbol =>
isPreemptible is false =>
R_PLT_PC is optimized to R_PC =>
in isStaticLinkTimeConstant, an error is emitted.

Reviewed By: pcc, grimar

Differential Revision: https://reviews.llvm.org/D72681
2020-01-14 10:12:28 -08:00
Fangrui Song d9819f3662 [ELF] Delete unintended --force-bti 2020-01-13 23:57:00 -08:00
Fangrui Song 7cd429f27d [ELF] Add -z force-ibt and -z shstk for Intel Control-flow Enforcement Technology
This patch is a joint work by Rui Ueyama and me based on D58102 by Xiang Zhang.

It adds Intel CET (Control-flow Enforcement Technology) support to lld.
The implementation follows the draft version of psABI which you can
download from https://github.com/hjl-tools/x86-psABI/wiki/X86-psABI.

CET introduces a new restriction on indirect jump instructions so that
you can limit the places to which you can jump to using indirect jumps.

In order to use the feature, you need to compile source files with
-fcf-protection=full.

* IBT is enabled if all input files are compiled with the flag. To force enabling ibt, pass -z force-ibt.
* SHSTK is enabled if all input files are compiled with the flag, or if -z shstk is specified.

IBT-enabled executables/shared objects have two PLT sections, ".plt" and
".plt.sec".  For the details as to why we have two sections, please read
the comments.

Reviewed By: xiangzhangllvm

Differential Revision: https://reviews.llvm.org/D59780
2020-01-13 23:39:28 -08:00
Alex Richardson 894f742acb [MIPS][ELF] Use PC-relative relocations in .eh_frame when possible
When compiling position-independent executables, we now use
DW_EH_PE_pcrel | DW_EH_PE_sdata4. However, the MIPS ABI does not define a
64-bit PC-relative ELF relocation so we cannot use sdata8 for the large
code model case. When using the large code model, we fall back to the
previous behaviour of generating absolute relocations.

With this change clang-generated .o files can be linked by LLD without
having to pass -Wl,-z,notext (which creates text relocations).
This is simpler than the approach used by ld.bfd, which rewrites the
.eh_frame section to convert absolute relocations into relative references.

I saw in D13104 that apparently ld.bfd did not accept pc-relative relocations
for MIPS ouput at some point. However, I also checked that recent ld.bfd
can process the clang-generated .o files so this no longer seems true.

Reviewed By: atanasyan
Differential Revision: https://reviews.llvm.org/D72228
2020-01-13 14:14:03 +00:00
Fangrui Song 2bfee35cb8 [MC][ELF] Emit a relocation if target is defined in the same section and is non-local
For a target symbol defined in the same section, currently we don't emit
a relocation if VariantKind is VK_None (with few exceptions like RISC-V
relaxation), while GNU as emits one. This causes program behavior
differences with and without -ffunction-sections, and can break intended
symbol interposition in a -shared link.

```
.globl foo
foo:
  call foo      # no relocation. On other targets, may be written as b foo, etc
  call bar      # a relocation if bar is in another section (e.g. -ffunction-sections)
  call foo@plt  # a relocation
```

Unify these cases by always emitting a relocation. If we ever want to
optimize `call foo` in -shared links, we should emit a STB_LOCAL alias
and call via the alias.

ARM/thumb2-beq-fixup.s: we now emit a relocation to global_thumb_fn as GNU as does.
X86/Inputs/align-branch-64-2.s: we now emit R_X86_64_PLT32 to foo as GNU does.

ELF/relax.s: rewrite the test as target-in-same-section.s .
We omitted relocations to `global` and now emit R_X86_64_PLT32.
Note, GNU as does not emit a relocation for `jmp global` (maybe its own
bug). Our new behavior is compatible except `jmp global`.

Reviewed By: peter.smith

Differential Revision: https://reviews.llvm.org/D72197
2020-01-12 13:46:24 -08:00
Tom Tan 7c81649219 [COFF] Align ARM64 range extension thunks at instruction boundary
RangeExtensionThunkARM64 is created for out-of-range branches on Windows ARM64
because branch instructions has limited bits to encode target address.
Currently, RangeExtensionThunkARM64 is appended to its referencing COFF section
from object file at link time without any alignment requirement, so if size of
the preceding COFF section is not aligned to instruction boundary (4 bytes),
RangeExtensionThunkARM64 will emit thunk instructions at unaligned address
which is never a valid branch target on ARM64, and usually triggers invalid
instruction exception when branching to it.

This PR fixes it by requiring such thunks to align at 4 bytes.

Differential revision: https://reviews.llvm.org/D72473
2020-01-10 19:03:17 -08:00
Sam Clegg 9cd985815a [lld][WebAssembly] Add libcall symbols to the link when LTO is being used.
This code is copied almost verbatim from the equivalent change to the
ELF linker:

- https://reviews.llvm.org/D50017
- https://reviews.llvm.org/D50475

The upshot is that libraries containing libcall (such as compiler-rt
and libc) can be compiled with LTO.

Fixes PR41384

Differential Revision: https://reviews.llvm.org/D71738
2020-01-10 11:01:05 -08:00
Fangrui Song 2d077d6dfa [ELF] Make TargetInfo::writeIgotPlt a no-op
RELA targets don't read initial .got.plt entries.
REL targets (ARM, x86-32) write the address of the IFUNC resolver to the
entry (`write32le(buf, s.getVA())`).

The default writeIgotPlt() is not meaningful. Make it a no-op. AArch64
and x86-64 will have 0 as initial .got.plt entries associated with
IFUNC.

Reviewed By: peter.smith

Differential Revision: https://reviews.llvm.org/D72474
2020-01-10 09:59:22 -08:00
James Henderson 6e3ca962fa [DebugInfo] Improve error message text
Unlike most of our errors in the debug line parser, the "no end of
sequence" message was missing any reference to which line table it
refererred to. This change adds the offset to this message.

Reviewed by: dblaikie

Differential Revision: https://reviews.llvm.org/D72443
2020-01-10 14:59:58 +00:00