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2020-02-06[MC][ELF] Rename MC related "Associated" to "LinkedToSym"Fangrui Song1-3/+3
"linked-to section" is used by the ELF spec. By analogy, "linked-to symbol" is a good name for the signature symbol. The word "linked-to" implies a directed edge and makes it clear its relation with "sh_link", while one can argue that "associated" means an undirected edge. Also, combine tests and add precise SMLoc to improve diagnostics. Reviewed By: eugenis, grimar, jhenderson Differential Revision: https://reviews.llvm.org/D74082
2020-01-20[MC] Improve a report_fatal_errorFangrui Song1-1/+1
2020-01-13[MC] Don't resolve relocations referencing STB_LOCAL STT_GNU_IFUNCFangrui Song1-1/+2
2020-01-12[MC][ELF] Emit a relocation if target is defined in the same section and is ↵Fangrui Song1-21/+1
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
2019-11-08[MC] Emit unused undefined symbol even if its binding is not setFangrui Song1-3/+0
Recommit r373168, which was reverted by r373242. This actually exposed a boringssl bug which has been fixed for more than one month. For the following two cases, we currently suppress the symbols. This patch emits them (compatible with GNU as). * `test2_a = undef`: if `undef` is otherwise unused. * `.hidden hidden`: if `hidden` is unused. This is the main point of the patch, because omitting the symbol would cause a linker semantic difference. It causes a behavior change that is not compatible with GNU as: .weakref foo1, bar1 When neither foo1 nor bar1 is used, we now emit bar1, which is arguably more consistent. Another change is that we will emit .TOC. for .TOC.@tocbase . For this directive, suppressing .TOC. can be seen as a size optimization, but we choose to drop it for simplicity and consistency.
2019-09-30Revert "[MC] Emit unused undefined symbol even if its binding is not set"Nico Weber1-0/+3
This reverts r373168. It caused PR43511. llvm-svn: 373242
2019-09-29[MC] Emit unused undefined symbol even if its binding is not setFangrui Song1-3/+0
For the following two cases, we currently suppress the symbols. This patch emits them (compatible with GNU as). * `test2_a = undef`: if `undef` is otherwise unused. * `.hidden hidden`: if `hidden` is unused. This is the main point of the patch, because omitting the symbol would cause a linker semantic difference. It causes a behavior change that is not compatible with GNU as: .weakref foo1, bar1 When neither foo1 nor bar1 is used, we now emit bar1, which is arguably more consistent. Another change is that we will emit .TOC. for .TOC.@tocbase . For this directive, suppressing .TOC. can be seen as a size optimization, but we choose to drop it for simplicity and consistency. llvm-svn: 373168
2019-09-27[Alignment][NFC] Remove unneeded llvm:: scoping on Align typesGuillaume Chatelet1-6/+6
llvm-svn: 373081
2019-09-13[Alignment] Introduce llvm::Align to MCSectionGuillaume Chatelet1-5/+5
Summary: This is patch is part of a series to introduce an Alignment type. See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html See this patch for the introduction of the type: https://reviews.llvm.org/D64790 Reviewers: courbet, JDevlieghere Subscribers: arsenm, sdardis, jvesely, nhaehnle, sbc100, hiraditya, aheejin, jrtc27, atanasyan, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D67486 llvm-svn: 371831
2019-09-12[Alignment] Move OffsetToAlignment to Alignment.hGuillaume Chatelet1-1/+2
Summary: This is patch is part of a series to introduce an Alignment type. See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html See this patch for the introduction of the type: https://reviews.llvm.org/D64790 Reviewers: courbet, JDevlieghere, alexshap, rupprecht, jhenderson Subscribers: sdardis, nemanjai, hiraditya, kbarton, jakehehrlich, jrtc27, MaskRay, atanasyan, jsji, seiya, cfe-commits, llvm-commits Tags: #clang, #llvm Differential Revision: https://reviews.llvm.org/D67499 llvm-svn: 371742
2019-09-07[ELF][MC] Set types of aliases of IFunc to STT_GNU_IFUNCFangrui Song1-0/+15
``` .type foo,@gnu_indirect_function .set foo,foo_resolver .set foo2,foo .set foo3,foo2 ``` The types of foo2 and foo3 should be STT_GNU_IFUNC, but we currently resolve them to the type of foo_resolver. This patch fixes it. Differential Revision: https://reviews.llvm.org/D67206 Patch by Senran Zhang llvm-svn: 371312
2019-08-23Revert r369233.Manoj Gupta1-14/+10
This breaks building of some projects like libfuse and alsa-lib that now fail when linking. Error details in PR43092. llvm-svn: 369790
2019-08-19[MC] Simplify ELFObjectWriter::recordRelocation. NFCFangrui Song1-22/+16
llvm-svn: 369248
2019-08-19[MC] Delete unnecessary diagnostic: "No relocation available to represent ↵Fangrui Song1-15/+1
this relative expression" Replace - error: No relocation available to represent this relative expression with + error: symbol 'undef' can not be undefined in a subtraction expression or + error: Cannot represent a difference across sections Keep !IsPcRel as an assertion after the two diagnostic checks are done. llvm-svn: 369239
2019-08-19[MC] Don't emit .symver redirected symbols to the symbol tableFangrui Song1-10/+14
GNU as keeps the original symbol in the symbol table for defined @ and @@, but suppresses it in other cases (@@@ or undefined). The original symbol is usually undesired: In a shared object, the original symbol can be localized with a version script, but it is hard to remove/localize in an archive: 1) a post-processing step removes the undesired original symbol 2) consumers (executable) of the archive are built with the version script Moreover, it can cause linker issues like binutils PR/18703 if the original symbol name and the base name of the versioned symbol is the same (both ld.bfd and gold have some code to work around defined @ and @@). In lld, if it sees f and f@v1: --version-script =(printf 'v1 {};') => f and f@v1 --version-script =(printf 'v1 { f; };') => f@v1 and f@@v1 It can be argued that @@@ added on 2000-11-13 corrected the @ and @@ mistake. This patch catches some more multiple version errors (defined @ and @@), and consistently suppress the original symbol. This addresses all the problems listed above. If the user wants other aliases to the versioned symbol, they can copy the original symbol to other symbol names with .set directive, e.g. .symver f, f@v1 # emit f@v1 but not f into .symtab .set f_impl, f # emit f_impl into .symtab llvm-svn: 369233
2019-08-15[llvm] Migrate llvm::make_unique to std::make_uniqueJonas Devlieghere1-2/+2
Now that we've moved to C++14, we no longer need the llvm::make_unique implementation from STLExtras.h. This patch is a mechanical replacement of (hopefully) all the llvm::make_unique instances across the monorepo. llvm-svn: 369013
2019-07-22Revert "Reland [ELF] Loose a condition for relocation with a symbol"Vlad Tsyrklevich1-0/+5
This reverts commit r366686 as it appears to be causing buildbot failures on sanitizer-x86_64-linux-android and sanitizer-x86_64-linux. llvm-svn: 366708
2019-07-22Reland [ELF] Loose a condition for relocation with a symbolNikola Prica1-5/+0
This patch was not the reason of the buildbot failure. Deleted code was introduced as a work around for a bug in the gold linker (http://sourceware.org/PR16794). Test case that was given as a reason for this part of code, the one on previous link, now works for the gold. This condition is too strict and when a code is compiled with debug info it forces generation of numerous relocations with symbol for architectures that do not have relocation addend. Reviewers: arsenm, espindola Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D64327 llvm-svn: 366686
2019-07-10Revert "[ELF] Loose a condition for relocation with a symbol"Nikola Prica1-0/+5
This reverts commit 8507eca1647118e73435b0ce1de8a1952a021d01. Reveting due to some suspicious failurse in santizer-x86_64-linux. llvm-svn: 365685
2019-07-10[ELF] Loose a condition for relocation with a symbolNikola Prica1-5/+0
Deleted code was introduced as a work around for a bug in the gold linker (http://sourceware.org/PR16794). Test case that was given as a reason for this part of code, the one on previous link, now works for the gold. This condition is too strict and when a code is compiled with debug info it forces generation of numerous relocations with symbol for architectures that do not have relocation addend. Reviewers: arsenm, espindola Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D64327 llvm-svn: 365618
2019-06-25AMDGPU/MC: Add .amdgpu_lds directiveNicolai Haehnle1-3/+7
Summary: The directive defines a symbol as an group/local memory (LDS) symbol. LDS symbols behave similar to common symbols for the purposes of ELF, using the processor-specific SHN_AMDGPU_LDS as section index. It is the linker and/or runtime loader's job to "instantiate" LDS symbols and resolve relocations that reference them. It is not possible to initialize LDS memory (not even zero-initialize as for .bss). We want to be able to link together objects -- starting with relocatable objects, but possible expanding to shared objects in the future -- that access LDS memory in a flexible way. LDS memory is in an address space that is entirely separate from the address space that contains the program image (code and normal data), so having program segments for it doesn't really make sense. Furthermore, we want to be able to compile multiple kernels in a compilation unit which have disjoint use of LDS memory. In that case, we may want to place LDS symbols differently for different kernels to save memory (LDS memory is very limited and physically private to each kernel invocation), so we can't simply place LDS symbols in a .lds section. Hence this solution where LDS symbols always stay undefined. Change-Id: I08cbc37a7c0c32f53f7b6123aa0afc91dbc1748f Reviewers: arsenm, rampitec, t-tye, b-sumner, jsjodin Subscribers: kzhuravl, jvesely, wdng, yaxunl, dstuttard, tpr, rupprecht, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D61493 llvm-svn: 364296
2019-06-07[MC][ELF] Don't create relocations with section symbols for STB_LOCAL ifuncFangrui Song1-0/+6
We should keep the symbol type (STT_GNU_IFUNC) for a local ifunc because it may result in an IRELATIVE reloc that the dynamic loader will use to resolve the address at startup time. There is another problem that is not fixed by this patch: a PC relative relocation should also create a relocation with the ifunc symbol. llvm-svn: 362767
2019-05-10[MC][ELF] Copy top 3 bits of st_other to .symver aliasesFangrui Song1-0/+1
On PowerPC64 ELFv2 ABI, the top 3 bits of st_other encode the local entry offset. A versioned symbol alias created by .symver should copy the bits from the source symbol. This partly fixes PR41048. A full fix needs tracking of .set assignments and updating st_other fields when finish() is called, see D56586. Patch by Alfredo Dal'Ava Júnior Differential Revision: https://reviews.llvm.org/D59436 llvm-svn: 360442
2019-04-23[llvm-mc] - Properly set the the address align field of the compressed sections.George Rimar1-2/+6
About the compressed sections spec says: (https://docs.oracle.com/cd/E37838_01/html/E36783/section_compression.html) sh_addralign fields of the section header for a compressed section reflect the requirements of the compressed section. Currently, llvm-mc always puts uncompressed section alignment to sh_addralign. It is not correct. zlib styled section contains an Elfxx_Chdr header, so we should either use 4 or 8 values depending on the target (Uncompressed section alignment is stored in ch_addralign field of the compression header). GNU assembler version 2.31.1 also has this issue, but in 2.32.51 it was already fixed. This is how it was found during debugging of the https://bugs.llvm.org/show_bug.cgi?id=40482 actually. Differential revision: https://reviews.llvm.org/D60965 llvm-svn: 358960
2019-04-12[MC] Fix typo: .symtab_shndxr -> .symtab_shndxFangrui Song1-1/+1
This special section is named .symtab_shndx, according to gABI Chapter 4 Sections, and the name is used by some other tools. Though the section type SHT_SYMTAB_SHNDX is what really matters, let's fix the typo introduced in rL204769 :) llvm-svn: 358247
2019-03-04[MC] Teach ELFObjectWriter that parse-time variables do not appear inNirav Dave1-0/+4
symbol table. llvm-svn: 355325
2019-02-14MC/ELF: Allow targets to set ABI versionKonstantin Zhuravlyov1-1/+2
Tests are in the follow up change Differential Revision: https://reviews.llvm.org/D57810 llvm-svn: 354072
2019-02-13[MC] Make symbol version errors non-fatalReid Kleckner1-6/+12
We stil don't have a source location, which is pretty lame, but at least we won't tell the user to file a clang bug report anymore. Fixes PR40712 llvm-svn: 353907
2019-01-19Update the file headers across all of the LLVM projects in the monorepoChandler Carruth1-4/+3
to reflect the new license. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351636
2018-12-05Recommit r348243 - "[llvm-mc] - Do not crash when referencing undefined ↵George Rimar1-0/+14
debug sections." The patch triggered an unrelated msan issue: LayoutOrder variable was not initialized. (http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-fast/builds/26794/steps/check-llvm%20msan/logs/stdio) It was fixed. Original commit message: MC has code that pre-creates few debug sections: https://github.com/llvm-mirror/llvm/blob/master/lib/MC/MCObjectFileInfo.cpp#L396 If users code has a reference to such section but does not redefine it, MC code currently asserts, because still thinks they are normally defined. The patch fixes the issue. Differential revision: https://reviews.llvm.org/D55173 ---- Modified : /llvm/trunk/lib/MC/ELFObjectWriter.cpp Added : /llvm/trunk/test/MC/ELF/undefined-debug.s llvm-svn: 348349
2018-12-04Revert r348243 "[llvm-mc] - Do not crash when referencing undefined debug ↵George Rimar1-14/+0
sections." It broke msan and asan bots it seems: http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-fast/builds/26794/steps/check-llvm%20msan/logs/stdio http://lab.llvm.org:8011/builders/clang-s390x-linux/builds/20993/steps/ninja%20check%201/logs/stdio llvm-svn: 348248
2018-12-04[llvm-mc] - Do not crash when referencing undefined debug sections.George Rimar1-0/+14
MC has code that pre-creates few debug sections: https://github.com/llvm-mirror/llvm/blob/master/lib/MC/MCObjectFileInfo.cpp#L396 If users code has a reference to such section but does not redefine it, MC code currently asserts, because still thinks they are normally defined. The patch fixes the issue. Differential revision: https://reviews.llvm.org/D55173 llvm-svn: 348243
2018-09-06The initial .text section generated in object files was missing theEric Christopher1-0/+3
SHF_ARM_PURECODE flag when being built with the -mexecute-only flag. All code sections of an ELF must have the flag set for the final .text section to be execute-only, otherwise the flag gets removed. A HasData flag is added to MCSection to aid in the determination that the section is empty. A virtual setTargetSectionFlags is added to MCELFObjectTargetWriter to allow subclasses to set target specific section flags to be added to sections which we then use in the ARM backend to set SHF_ARM_PURECODE. Patch by Ivan Lozano! Reviewed By: echristo Differential Revision: https://reviews.llvm.org/D48792 llvm-svn: 341593
2018-08-06MC: Redirect .addrsig directives referring to private (.L) symbols to the ↵Peter Collingbourne1-0/+2
section symbol. This matches our behaviour for regular (i.e. relocated) references to private symbols and therefore avoids needing to unnecessarily write address-significant .L symbols to the object file's symbol table, which can interfere with stack traces. Fixes check-cfi after r339050. llvm-svn: 339066
2018-07-17MC: Implement support for new .addrsig and .addrsig_sym directives.Peter Collingbourne1-0/+37
Part of the address-significance tables proposal: http://lists.llvm.org/pipermail/llvm-dev/2018-May/123514.html Differential Revision: https://reviews.llvm.org/D47744 llvm-svn: 337328
2018-06-02[MC] Add assembler support for .cg_profile.Michael J. Spencer1-0/+20
Object FIle Representation At codegen time this is emitted into the ELF file a pair of symbol indices and a weight. In assembly it looks like: .cg_profile a, b, 32 .cg_profile freq, a, 11 .cg_profile freq, b, 20 When writing an ELF file these are put into a SHT_LLVM_CALL_GRAPH_PROFILE (0x6fff4c02) section as (uint32_t, uint32_t, uint64_t) tuples as (from symbol index, to symbol index, weight). Differential Revision: https://reviews.llvm.org/D44965 llvm-svn: 333823
2018-05-21MC: Introduce an ELF dwo object writer and teach llvm-mc about it.Peter Collingbourne1-15/+93
Part of PR37466. Differential Revision: https://reviews.llvm.org/D47051 llvm-svn: 332875
2018-05-21MC: Extract a derived class from ELFObjectWriter. NFCI.Peter Collingbourne1-13/+19
This class will be used to create regular, non-split ELF files. Part of PR37466. Differential Revision: https://reviews.llvm.org/D47049 llvm-svn: 332870
2018-05-21MC: Extract ELFObjectWriter's ELF writing functionality into an ELFWriter ↵Peter Collingbourne1-350/+368
class. NFCI. The idea is that we will be able to use this class to create multiple files. Differential Revision: https://reviews.llvm.org/D47048 llvm-svn: 332867
2018-05-21MC: Remove stream and output functions from MCObjectWriter. NFCI.Peter Collingbourne1-1/+1
Part of PR37466. Differential Revision: https://reviews.llvm.org/D47043 llvm-svn: 332864
2018-05-21MC: Have the object writers return the number of bytes written. NFCI.Peter Collingbourne1-3/+7
This removes the last external use of the stream. Part of PR37466. Differential Revision: https://reviews.llvm.org/D47042 llvm-svn: 332863
2018-05-21MC: Change object writers to use endian::Writer. NFCI.Peter Collingbourne1-67/+69
Part of PR37466. Differential Revision: https://reviews.llvm.org/D47040 llvm-svn: 332861
2018-05-21MC: Change MCAssembler::writeSectionData and writeFragmentPadding to take a ↵Peter Collingbourne1-5/+2
raw_ostream. NFCI. Also clean up a couple of hacks where we were writing the section contents to another stream by setting the object writer's stream, writing and setting it back. Part of PR37466. Differential Revision: https://reviews.llvm.org/D47038 llvm-svn: 332858
2018-05-18Support: Simplify endian stream interface. NFCI.Peter Collingbourne1-4/+2
Provide some free functions to reduce verbosity of endian-writing a single value, and replace the endianness template parameter with a field. Part of PR37466. Differential Revision: https://reviews.llvm.org/D47032 llvm-svn: 332757
2018-05-08MC: Remove dead code. NFCI.Peter Collingbourne1-1/+0
We should never emit an SHT_DYNSYM into an object file. llvm-svn: 331821
2018-05-07[MC] ELFObjectWriter: Removing unneeded variable and castSam Clegg1-5/+4
Differential Revision: https://reviews.llvm.org/D46289 llvm-svn: 331704
2018-04-27ELFObjectWriter: Allow one unique symver per symbolVlad Tsyrklevich1-0/+4
Summary: Only allow a single unique .symver alias per symbol. This matches the behavior of gas. I noticed that we ignored multiple mismatched symver directives looking at https://reviews.llvm.org/D45798 Reviewers: pcc, tejohnson, espindola Reviewed By: pcc Subscribers: emaste, arichardson, llvm-commits, kcc Differential Revision: https://reviews.llvm.org/D45845 llvm-svn: 331078
2018-03-09Delay creating an alias for @@@.Rafael Espindola1-56/+19
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. llvm-svn: 327160
2017-10-10[MC] Thread unique_ptr<MCObjectWriter> through the create.*ObjectWriterLang Hames1-2/+3
functions. This makes the ownership of the resulting MCObjectWriter clear, and allows us to remove one instance of MCObjectStreamer's bizarre "holding ownership via someone else's reference" trick. llvm-svn: 315327
2017-10-09[MC] Plumb unique_ptr<MCELFObjectTargetWriter> through createELFObjectWriter toLang Hames1-7/+8
ELFObjectWriter's constructor. Fixes the same ownership issue for ELF that r315245 did for MachO: ELFObjectWriter takes ownership of its MCELFObjectTargetWriter, so we want to pass this through to the constructor via a unique_ptr, rather than a raw ptr. llvm-svn: 315254
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