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* [OpenMP][Clang] Support for target math functionsGheorghe-Teodor Bercea2019-05-081-0/+18
| | | | | | | | | | | | | | | | | | | | | | | Summary: In this patch we propose a temporary solution to resolving math functions for the NVPTX toolchain, temporary until OpenMP variant is supported by Clang. We intercept the inclusion of math.h and cmath headers and if we are in the OpenMP-NVPTX case, we re-use CUDA's math function resolution mechanism. Authors: @gtbercea @jdoerfert Reviewers: hfinkel, caomhin, ABataev, tra Reviewed By: hfinkel, ABataev, tra Subscribers: JDevlieghere, mgorny, guansong, cfe-commits, jdoerfert Tags: #clang Differential Revision: https://reviews.llvm.org/D61399 llvm-svn: 360265
* Revert "[OpenMP][Clang] Support for target math functions"Jonas Devlieghere2019-05-071-15/+0
| | | | | | | | | | | | | | This commit appears to be breaking stage-2 builds on GreenDragon. The OpenMP wrappers for cmath and math.h are copied into the root of the resource directory and cause a cyclic dependency in module 'Darwin': Darwin -> std -> Darwin. This blows up when CMake is testing for modules support and breaks all stage 2 module builds, including the ThinLTO bot and all LLDB bots. CMake Error at cmake/modules/HandleLLVMOptions.cmake:497 (message): LLVM_ENABLE_MODULES is not supported by this compiler llvm-svn: 360192
* [OpenMP][Clang] Support for target math functionsGheorghe-Teodor Bercea2019-05-061-0/+15
| | | | | | | | | | | | | | | | | | | | | | | Summary: In this patch we propose a temporary solution to resolving math functions for the NVPTX toolchain, temporary until OpenMP variant is supported by Clang. We intercept the inclusion of math.h and cmath headers and if we are in the OpenMP-NVPTX case, we re-use CUDA's math function resolution mechanism. Authors: @gtbercea @jdoerfert Reviewers: hfinkel, caomhin, ABataev, tra Reviewed By: hfinkel, ABataev, tra Subscribers: mgorny, guansong, cfe-commits, jdoerfert Tags: #clang Differential Revision: https://reviews.llvm.org/D61399 llvm-svn: 360063
* Enable frame pointer elimination for OpenBSD on powerpc.Brad Smith2019-04-191-0/+1
| | | | llvm-svn: 358775
* [Driver] Simplify -g level computation and its interaction with -gsplit-dwarfFangrui Song2019-04-171-34/+19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: When -gsplit-dwarf is used together with other -g options, in most cases the computed debug info level is decided by the last -g option, with one special case (see below). This patch drops that special case and thus makes it easy to reason about: // If a lower debug level -g comes after -gsplit-dwarf, in some cases // -gsplit-dwarf is cancelled. -gsplit-dwarf -g0 => 0 -gsplit-dwarf -gline-directives-only => DebugDirectivesOnly -gsplit-dwarf -gmlt -fsplit-dwarf-inlining => 1 -gsplit-dwarf -gmlt -fno-split-dwarf-inlining => 1 + split // If -gsplit-dwarf comes after -g options, with this patch, the net // effect is 2 + split for all combinations -g0 -gsplit-dwarf => 2 + split -gline-directives-only -gsplit-dwarf => 2 + split -gmlt -gsplit-dwarf -fsplit-dwarf-inlining => 2 + split -gmlt -gsplit-dwarf -fno-split-dwarf-inlining => 1 + split (before) 2 + split (after) The last case has been changed. In general, if the user intends to lower debug info level, place that -g option after -gsplit-dwarf. Some context: In gcc, the last of -gsplit-dwarf -g0 -g1 -g2 -g3 -ggdb[0-3] -gdwarf-* ... decides the debug info level (-gsplit-dwarf -gdwarf-* have level 2). It is a bit unfortunate that -gsplit-dwarf -gdwarf-* ... participate in the level computation but that is the status quo. Reviewers: dblaikie, echristo, probinson Reviewed By: dblaikie, probinson Subscribers: probinson, aprantl, jdoerfert, cfe-commits Tags: #clang Differential Revision: https://reviews.llvm.org/D59923 llvm-svn: 358544
* DebugInfo: Default to standalone debug when tuning for LLDBDavid Blaikie2019-04-161-3/+4
| | | | | | | | | | | | | | | | | LLDB can't currently handle Clang's default (limit/no-standalone) DWARF, so platforms that default to LLDB (Darwin) or anyone else manually requesting LLDB tuning, should also get standalone DWARF. That doesn't mean a user can't explicitly enable (because they have other reasons to prefer standalone DWARF (such as that they're only building half their application with debug info enabled, and half without - or because they're tuning for GDB, but want to be able to use it under LLDB too (this is the default on FreeBSD))) or disable (testing LLDB fixes/improvements that handle no-standalone mode, building C code, perhaps, which wouldn't have the LLDB<>no-standalone conflict, etc) the feature regardless of the tuning. llvm-svn: 358464
* [c++20] Enable driver and frontend support for building and usingRichard Smith2019-04-141-5/+10
| | | | | | modules when -std=c++2a is specified. llvm-svn: 358355
* Enable frame pointer elimination for OpenBSD on x86 and mips64.Brad Smith2019-04-121-0/+12
| | | | llvm-svn: 358245
* Range-style std::find{,_if} -> llvm::find{,_if}. NFCFangrui Song2019-03-311-3/+1
| | | | llvm-svn: 357359
* Adds `-ftime-trace` option to clang that produces Chrome `chrome://tracing` ↵Anton Afanasyev2019-03-301-0/+1
| | | | | | | | | | | | | | compatible JSON profiling output dumps. This change adds hierarchical "time trace" profiling blocks that can be visualized in Chrome, in a "flame chart" style. Each profiling block can have a "detail" string that for example indicates the file being processed, template name being instantiated, function being optimized etc. This is taken from GitHub PR: https://github.com/aras-p/llvm-project-20170507/pull/2 Patch by Aras Pranckevičius. Differential Revision: https://reviews.llvm.org/D58675 llvm-svn: 357340
* [Driver] Default Android toolchains to noexecstack.Dan Albert2019-03-281-1/+4
| | | | | | | | | | | | | | Android does not support executable stacks. Reviewers: srhines, pirama Reviewed By: pirama Subscribers: cfe-commits Differential Revision: https://reviews.llvm.org/D53343 llvm-svn: 357197
* [Driver] Allow -gsplit-dwarf on ELF OSes other than Linux and FuchsiaFangrui Song2019-03-281-5/+4
| | | | | | | | | | | In gcc, -gsplit-dwarf is handled in gcc/gcc.c as a spec (ASM_FINAL_SPEC): objcopy --extract-dwo + objcopy --strip-dwo. In gcc/opts.c, -gsplit_dwarf has the same semantic of a -g. Except for the availability of the external command 'objcopy', nothing precludes the feature working on other ELF OSes. llvm doesn't use objcopy, so it doesn't have to exclude other OSes. llvm-svn: 357150
* Revert the r348352 "[clang] - Simplify tools::SplitDebugName."George Rimar2019-03-271-2/+2
| | | | | | | | | This partially reverts the r348352 (https://reviews.llvm.org/D55006) because of https://bugs.llvm.org/show_bug.cgi?id=41161. I did not revert the test case file because it passes fine now. llvm-svn: 357061
* [RISCV] Pass -target-abi to -cc1asRoger Ferrer Ibanez2019-03-261-0/+14
| | | | | | | | | | | | | | | | | The RISC-V assembler needs the target ABI because it defines a flag of the ELF file, as described in [1]. Make clang (the driver) to pass the target ABI to -cc1as in exactly the same way it does for -cc1. Currently -cc1as knows about -target-abi but is not handling it. Handle it and pass it to the MC layer via MCTargetOptions. [1] https://github.com/riscv/riscv-elf-psabi-doc/blob/master/riscv-elf.md#file-header Differential Revision: https://reviews.llvm.org/D59298 llvm-svn: 356981
* [Driver] Pass -malign-double from the driver to the cc1 command lineCraig Topper2019-03-211-0/+1
| | | | | | | | | | -malign-double is currently only implemented in the -cc1 interface. But its declared in Options.td so it is a driver option too. But you try to use it with the driver you'll get a message about the option being unused. This patch teaches the driver to pass the option through to cc1 so it won't be unused. The Options.td says the option is x86 only but I didn't see any x86 specific code in its impementation in cc1 so not sure if the documentation is wrong or if I should only pass this option through the driver on x86 targets. Differential Revision: https://reviews.llvm.org/D59624 llvm-svn: 356706
* Reland "[Remarks] Add -foptimization-record-passes to filter remark emission"Francis Visoiu Mistrih2019-03-121-0/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | Currently we have -Rpass for filtering the remarks that are displayed as diagnostics, but when using -fsave-optimization-record, there is no way to filter the remarks while generating them. This adds support for filtering remarks by passes using a regex. Ex: `clang -fsave-optimization-record -foptimization-record-passes=inline` will only emit the remarks coming from the pass `inline`. This adds: * `-fsave-optimization-record` to the driver * `-opt-record-passes` to cc1 * `-lto-pass-remarks-filter` to the LTOCodeGenerator * `--opt-remarks-passes` to lld * `-pass-remarks-filter` to llc, opt, llvm-lto, llvm-lto2 * `-opt-remarks-passes` to gold-plugin Differential Revision: https://reviews.llvm.org/D59268 Original llvm-svn: 355964 llvm-svn: 355984
* Revert "[Remarks] Add -foptimization-record-passes to filter remark emission"Francis Visoiu Mistrih2019-03-121-8/+0
| | | | | | This reverts commit 20fff32b7d1f1a1bd417b22aa9f26ededd97a3e5. llvm-svn: 355976
* [Remarks] Add -foptimization-record-passes to filter remark emissionFrancis Visoiu Mistrih2019-03-121-0/+8
| | | | | | | | | | | | | | | | | | | | | | | | Currently we have -Rpass for filtering the remarks that are displayed as diagnostics, but when using -fsave-optimization-record, there is no way to filter the remarks while generating them. This adds support for filtering remarks by passes using a regex. Ex: `clang -fsave-optimization-record -foptimization-record-passes=inline` will only emit the remarks coming from the pass `inline`. This adds: * `-fsave-optimization-record` to the driver * `-opt-record-passes` to cc1 * `-lto-pass-remarks-filter` to the LTOCodeGenerator * `--opt-remarks-passes` to lld * `-pass-remarks-filter` to llc, opt, llvm-lto, llvm-lto2 * `-opt-remarks-passes` to gold-plugin Differential Revision: https://reviews.llvm.org/D59268 llvm-svn: 355964
* Order File Instrumentation: add clang support for -forder-file-instrumentationManman Ren2019-03-041-0/+11
| | | | | | | | When -forder-file-instrumentation is on, we pass llvm flag to enable the order file instrumentation pass. https://reviews.llvm.org/D58751 llvm-svn: 355333
* [PGO] Clang part of change for context-sensitive PGO (part1)Rong Xu2019-03-041-3/+33
| | | | | | | | | | Part 1 of CSPGO change in Clang. This includes changes in clang options and calls to llvm PassManager. Tests will be committed in part2. This change needs the PassManager change in llvm. Differential Revision: https://reviews.llvm.org/D54176 llvm-svn: 355331
* Fix file headers. NFCFangrui Song2019-03-011-1/+1
| | | | llvm-svn: 355176
* [WebAssembly] Remove uses of ThreadModelThomas Lively2019-02-281-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: In the clang UI, replaces -mthread-model posix with -matomics as the source of truth on threading. In the backend, replaces -thread-model=posix with the atomics target feature, which is now collected on the WebAssemblyTargetMachine along with all other used features. These collected features will also be used to emit the target features section in the future. The default configuration for the backend is thread-model=posix and no atomics, which was previously an invalid configuration. This change makes the default valid because the thread model is ignored. A side effect of this change is that objects are never emitted with passive segments. It will instead be up to the linker to decide whether sections should be active or passive based on whether atomics are used in the final link. Reviewers: aheejin, sbc100, dschuff Subscribers: mehdi_amini, jgravelle-google, hiraditya, sunfish, steven_wu, dexonsmith, rupprecht, jfb, jdoerfert, cfe-commits, llvm-commits Tags: #clang, #llvm Differential Revision: https://reviews.llvm.org/D58742 llvm-svn: 355112
* [OPENMP][NVPTX]Use faster teams reduction algorithm.Alexey Bataev2019-02-201-0/+2
| | | | | | | A faster way to reduce the values in teams reductions was found, the codegen is updated to use this faster algorithm and new runtime functions. llvm-svn: 354479
* [ARM] Add pre-defined macros for ROPI and RWPIOliver Stannard2019-02-181-0/+7
| | | | | | | | | This adds ACLE-defined macros to test for code being compiled in the ROPI and RWPI position-independence modes. Differential revision: https://reviews.llvm.org/D23610 llvm-svn: 354265
* [WebAssembly] Make thread-related options consistentHeejin Ahn2019-02-111-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: There have been three options related to threads and users had to set all three of them separately to get the correct compilation results. This makes sure the relationship between the options makes sense and sets necessary options for users if only part of the necessary options are specified. This does: - Remove `-matomics`; this option alone does not enable anything, so removed it to not confuse users. - `-mthread-model posix` sets `-target-feature +atomics` - `-pthread` sets both `-target-feature +atomics` and `-mthread-model posix` Also errors out when explicitly given options don't match, such as `-pthread` is given with `-mthread-model single`. Reviewers: dschuff, sbc100, tlively, sunfish Subscribers: jgravelle-google, jfb, cfe-commits Tags: #clang Differential Revision: https://reviews.llvm.org/D57874 llvm-svn: 353761
* Do not use frame pointer by default for MSP430Anton Korobeynikov2019-02-051-0/+1
| | | | | | | | | | | This is suggested by 3.3.9 of MSP430 EABI document. We do allow user to manually enable frame pointer. GCC toolchain uses the same behavior. Patch by Dmitry Mikushev! Differential Revision: https://reviews.llvm.org/D56925 llvm-svn: 353212
* [NewPM] Add support for new-PM plugins to clangPhilip Pfaffe2019-02-021-0/+7
| | | | | | | | | | | | | | | Summary: This adds support for new-PM plugin loading to clang. The option `-fpass-plugin=` may be used to specify a dynamic shared object file that adheres to the PassPlugin API. Tested: created simple plugin that registers an EP callback; with optimization level > 0, the pass is run as expected. Committed on behalf of Marco Elver Differential Revision: https://reviews.llvm.org/D56935 llvm-svn: 352972
* [CUDA] Propagate detected version of CUDA to cc1Artem Belevich2019-01-311-2/+14
| | | | | | | | | | | | | ..and use it to control that parts of CUDA compilation that depend on the specific version of CUDA SDK. This patch has a placeholder for a 'new launch API' support which is in a separate patch. The list will be further extended in the upcoming patch to support CUDA-10.1. Differential Revision: https://reviews.llvm.org/D57487 llvm-svn: 352798
* Update the file headers across all of the LLVM projects in the monorepoChandler Carruth2019-01-191-4/+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
* [mips] Add '-mrelax-pic-calls', '-mno-relax-pic-calls'Vladimir Stefanovic2019-01-181-0/+8
| | | | | | | | | | | These two options enable/disable emission of R_{MICRO}MIPS_JALR fixups along with PIC calls. The linker may then try to turn PIC calls into direct jumps. By default, these fixups do get emitted by the backend, use '-mno-relax-pic-calls' to omit them. Differential revision: https://reviews.llvm.org/D56878 llvm-svn: 351579
* [MSP430] Provide a toolchain descriptionAnton Korobeynikov2019-01-151-0/+3
| | | | | | | | | | | | | | | This is an initial implementation for msp430 toolchain including -mmcu option support -mhwmult options support -integrated-as by default The toolchain uses msp430-elf-as as a linker and supports msp430-gcc toolchain tree. Patch by Kristina Bessonova! Differential Revision: https://reviews.llvm.org/D56658 llvm-svn: 351228
* [LTO] Add option to enable LTOUnit splitting, and disable unless neededTeresa Johnson2019-01-111-0/+11
| | | | | | | | | | | | | | | | | | | | Summary: Adds a new -f[no]split-lto-unit flag that is disabled by default to control module splitting during ThinLTO. It is automatically enabled for -fsanitize=cfi and -fwhole-program-vtables. The new EnableSplitLTOUnit codegen flag is passed down to llvm via a new module flag of the same name. Depends on D53890. Reviewers: pcc Subscribers: ormris, mehdi_amini, inglorion, eraman, steven_wu, dexonsmith, cfe-commits, llvm-commits Differential Revision: https://reviews.llvm.org/D53891 llvm-svn: 350949
* [OpenMP] Add flag for preventing the extension to 64 bits for the collapse ↵Gheorghe-Teodor Bercea2019-01-091-0/+4
| | | | | | | | | | | | | | | | loop counter Summary: Introduce a compiler flag for cases when the user knows that the collapsed loop counter can be safely represented using at most 32 bits. This will prevent the emission of expensive mathematical operations (such as the div operation) on the iteration variable using 64 bits where 32 bit operations are sufficient. Reviewers: ABataev, caomhin Reviewed By: ABataev Subscribers: hfinkel, kkwli0, guansong, cfe-commits Differential Revision: https://reviews.llvm.org/D55928 llvm-svn: 350758
* [Driver] Default to -fno-addrsig on Android.Dan Albert2019-01-081-0/+1
| | | | | | | | | | | | | | Summary: The Android NDK still uses GNU binutils by default. Reviewers: srhines, pirama Reviewed By: srhines Subscribers: cfe-commits Differential Revision: https://reviews.llvm.org/D56456 llvm-svn: 350668
* [Driver] Disable -faddrsig on Gentoo by defaultMichal Gorny2018-12-231-0/+2
| | | | | | | | | | | | | | Gentoo supports combining clang toolchain with GNU binutils, and many users actually do that. As -faddrsig is not supported by GNU strip, this results in a lot of warnings. Disable it by default and let users enable it explicitly if they want it; with the intent of reevaluating when the underlying feature becomes standarized. See also: https://bugs.gentoo.org/667854 Differential Revision: https://reviews.llvm.org/D56047 llvm-svn: 350028
* [driver] [analyzer] Fix --analyze -Xanalyzer after r349863.Artem Dergachev2018-12-211-2/+13
| | | | | | | | | | | | | | If an -analyzer-config is passed through -Xanalyzer, it is not found while looking for -Xclang. Additionally, don't emit -analyzer-config-compatibility-mode for *every* -analyzer-config flag we encounter; one is enough. https://reviews.llvm.org/D55823 rdar://problem/46504165 llvm-svn: 349866
* Revert "Revert "[driver] [analyzer] Fix a backward compatibility issue after ↵George Karpenkov2018-12-211-3/+7
| | | | | | | | | | r348038."" This reverts commit 144927939587b790c0536f4ff08245043fc8d733. Fixes the bug in the original commit. llvm-svn: 349863
* Revert "[driver] [analyzer] Fix a backward compatibility issue after r348038."Artem Dergachev2018-12-201-10/+3
| | | | | | | | | | | | This reverts commits r349824, r349828, r349835. More buildbot failures were noticed. Differential Revision: https://reviews.llvm.org/D55823 rdar://problem/46504165 llvm-svn: 349843
* [driver] [analyzer] Fix a backward compatibility issue after r348038.Artem Dergachev2018-12-201-3/+10
| | | | | | | | | | | | | | | | | | | Since r348038 we emit an error every time an -analyzer-config option is not found. The driver, however, suppresses this error with another flag, -analyzer-config-compatibility-mode, so backwards compatibility is maintained, while analyzer developers still enjoy the new typo-free experience. The backwards compatibility turns out to be still broken when the -analyze action is not specified; it is still possible to specify -analyzer-config in that case. This should be fixed now. Patch by Kristóf Umann! Differential Revision: https://reviews.llvm.org/D55823 rdar://problem/46504165 llvm-svn: 349824
* Replace getOS() == llvm::Triple::*BSD with isOS*BSD() [NFCI]Michal Gorny2018-12-201-5/+5
| | | | | | | | | | | | Replace multiple comparisons of getOS() value with FreeBSD, NetBSD, OpenBSD and DragonFly with matching isOS*BSD() methods. This should improve the consistency of coding style without changing the behavior. Direct getOS() comparisons were left whenever used in switch or switch- like context. Differential Revision: https://reviews.llvm.org/D55916 llvm-svn: 349752
* Disable -faddsig by default for PS4 target.Douglas Yung2018-12-191-0/+1
| | | | llvm-svn: 349691
* [Driver] Disable -faddrsig by default on NetBSDMichal Gorny2018-12-191-1/+2
| | | | | | | | | | Avoid passing -faddrsig by default on NetBSD. This platform is still using old GNU binutils that crashes on executables containing those sections. Differential Revision: https://reviews.llvm.org/D55828 llvm-svn: 349647
* [Driver][PS4] Do not implicitly link against asan or ubsan if -nostdlib or ↵Pierre Gousseau2018-12-181-1/+2
| | | | | | | | | | | | -nodefaultlibs on PS4. NFC for targets other than PS4. Respect -nostdlib and -nodefaultlibs when enabling asan or ubsan. Differential Revision: https://reviews.llvm.org/D55712 llvm-svn: 349508
* Automatic variable initializationJF Bastien2018-12-181-0/+45
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: Add an option to initialize automatic variables with either a pattern or with zeroes. The default is still that automatic variables are uninitialized. Also add attributes to request uninitialized on a per-variable basis, mainly to disable initialization of large stack arrays when deemed too expensive. This isn't meant to change the semantics of C and C++. Rather, it's meant to be a last-resort when programmers inadvertently have some undefined behavior in their code. This patch aims to make undefined behavior hurt less, which security-minded people will be very happy about. Notably, this means that there's no inadvertent information leak when: - The compiler re-uses stack slots, and a value is used uninitialized. - The compiler re-uses a register, and a value is used uninitialized. - Stack structs / arrays / unions with padding are copied. This patch only addresses stack and register information leaks. There's many more infoleaks that we could address, and much more undefined behavior that could be tamed. Let's keep this patch focused, and I'm happy to address related issues elsewhere. To keep the patch simple, only some `undef` is removed for now, see `replaceUndef`. The padding-related infoleaks are therefore not all gone yet. This will be addressed in a follow-up, mainly because addressing padding-related leaks should be a stand-alone option which is implied by variable initialization. There are three options when it comes to automatic variable initialization: 0. Uninitialized This is C and C++'s default. It's not changing. Depending on code generation, a programmer who runs into undefined behavior by using an uninialized automatic variable may observe any previous value (including program secrets), or any value which the compiler saw fit to materialize on the stack or in a register (this could be to synthesize an immediate, to refer to code or data locations, to generate cookies, etc). 1. Pattern initialization This is the recommended initialization approach. Pattern initialization's goal is to initialize automatic variables with values which will likely transform logic bugs into crashes down the line, are easily recognizable in a crash dump, without being values which programmers can rely on for useful program semantics. At the same time, pattern initialization tries to generate code which will optimize well. You'll find the following details in `patternFor`: - Integers are initialized with repeated 0xAA bytes (infinite scream). - Vectors of integers are also initialized with infinite scream. - Pointers are initialized with infinite scream on 64-bit platforms because it's an unmappable pointer value on architectures I'm aware of. Pointers are initialize to 0x000000AA (small scream) on 32-bit platforms because 32-bit platforms don't consistently offer unmappable pages. When they do it's usually the zero page. As people try this out, I expect that we'll want to allow different platforms to customize this, let's do so later. - Vectors of pointers are initialized the same way pointers are. - Floating point values and vectors are initialized with a negative quiet NaN with repeated 0xFF payload (e.g. 0xffffffff and 0xffffffffffffffff). NaNs are nice (here, anways) because they propagate on arithmetic, making it more likely that entire computations become NaN when a single uninitialized value sneaks in. - Arrays are initialized to their homogeneous elements' initialization value, repeated. Stack-based Variable-Length Arrays (VLAs) are runtime-initialized to the allocated size (no effort is made for negative size, but zero-sized VLAs are untouched even if technically undefined). - Structs are initialized to their heterogeneous element's initialization values. Zero-size structs are initialized as 0xAA since they're allocated a single byte. - Unions are initialized using the initialization for the largest member of the union. Expect the values used for pattern initialization to change over time, as we refine heuristics (both for performance and security). The goal is truly to avoid injecting semantics into undefined behavior, and we should be comfortable changing these values when there's a worthwhile point in doing so. Why so much infinite scream? Repeated byte patterns tend to be easy to synthesize on most architectures, and otherwise memset is usually very efficient. For values which aren't entirely repeated byte patterns, LLVM will often generate code which does memset + a few stores. 2. Zero initialization Zero initialize all values. This has the unfortunate side-effect of providing semantics to otherwise undefined behavior, programs therefore might start to rely on this behavior, and that's sad. However, some programmers believe that pattern initialization is too expensive for them, and data might show that they're right. The only way to make these programmers wrong is to offer zero-initialization as an option, figure out where they are right, and optimize the compiler into submission. Until the compiler provides acceptable performance for all security-minded code, zero initialization is a useful (if blunt) tool. I've been asked for a fourth initialization option: user-provided byte value. This might be useful, and can easily be added later. Why is an out-of band initialization mecanism desired? We could instead use -Wuninitialized! Indeed we could, but then we're forcing the programmer to provide semantics for something which doesn't actually have any (it's uninitialized!). It's then unclear whether `int derp = 0;` lends meaning to `0`, or whether it's just there to shut that warning up. It's also way easier to use a compiler flag than it is to manually and intelligently initialize all values in a program. Why not just rely on static analysis? Because it cannot reason about all dynamic code paths effectively, and it has false positives. It's a great tool, could get even better, but it's simply incapable of catching all uses of uninitialized values. Why not just rely on memory sanitizer? Because it's not universally available, has a 3x performance cost, and shouldn't be deployed in production. Again, it's a great tool, it'll find the dynamic uses of uninitialized variables that your test coverage hits, but it won't find the ones that you encounter in production. What's the performance like? Not too bad! Previous publications [0] have cited 2.7 to 4.5% averages. We've commmitted a few patches over the last few months to address specific regressions, both in code size and performance. In all cases, the optimizations are generally useful, but variable initialization benefits from them a lot more than regular code does. We've got a handful of other optimizations in mind, but the code is in good enough shape and has found enough latent issues that it's a good time to get the change reviewed, checked in, and have others kick the tires. We'll continue reducing overheads as we try this out on diverse codebases. Is it a good idea? Security-minded folks think so, and apparently so does the Microsoft Visual Studio team [1] who say "Between 2017 and mid 2018, this feature would have killed 49 MSRC cases that involved uninitialized struct data leaking across a trust boundary. It would have also mitigated a number of bugs involving uninitialized struct data being used directly.". They seem to use pure zero initialization, and claim to have taken the overheads down to within noise. Don't just trust Microsoft though, here's another relevant person asking for this [2]. It's been proposed for GCC [3] and LLVM [4] before. What are the caveats? A few! - Variables declared in unreachable code, and used later, aren't initialized. This goto, Duff's device, other objectionable uses of switch. This should instead be a hard-error in any serious codebase. - Volatile stack variables are still weird. That's pre-existing, it's really the language's fault and this patch keeps it weird. We should deprecate volatile [5]. - As noted above, padding isn't fully handled yet. I don't think these caveats make the patch untenable because they can be addressed separately. Should this be on by default? Maybe, in some circumstances. It's a conversation we can have when we've tried it out sufficiently, and we're confident that we've eliminated enough of the overheads that most codebases would want to opt-in. Let's keep our precious undefined behavior until that point in time. How do I use it: 1. On the command-line: -ftrivial-auto-var-init=uninitialized (the default) -ftrivial-auto-var-init=pattern -ftrivial-auto-var-init=zero -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang 2. Using an attribute: int dont_initialize_me __attribute((uninitialized)); [0]: https://users.elis.ugent.be/~jsartor/researchDocs/OOPSLA2011Zero-submit.pdf [1]: https://twitter.com/JosephBialek/status/1062774315098112001 [2]: https://outflux.net/slides/2018/lss/danger.pdf [3]: https://gcc.gnu.org/ml/gcc-patches/2014-06/msg00615.html [4]: https://github.com/AndroidHardeningArchive/platform_external_clang/commit/776a0955ef6686d23a82d2e6a3cbd4a6a882c31c [5]: http://wg21.link/p1152 I've also posted an RFC to cfe-dev: http://lists.llvm.org/pipermail/cfe-dev/2018-November/060172.html <rdar://problem/39131435> Reviewers: pcc, kcc, rsmith Subscribers: JDevlieghere, jkorous, dexonsmith, cfe-commits Differential Revision: https://reviews.llvm.org/D54604 llvm-svn: 349442
* [darwin][arm64] use the "cyclone" CPU for Darwin even when `-arch`Alex Lorenz2018-12-171-1/+1
| | | | | | | | | | | | | | | | is not specified The -target option allows the user to specify the build target using LLVM triple. The triple includes the arch, and so the -arch option is redundant. This should work just as well without the -arch. However, the driver has a bug in which it doesn't target the "Cyclone" CPU for darwin if -target is used without -arch. This commit fixes this issue. rdar://46743182 Differential Revision: https://reviews.llvm.org/D55731 llvm-svn: 349382
* Implement -frecord-command-line (-frecord-gcc-switches)Scott Linder2018-12-141-7/+22
| | | | | | | | | | | | | | | | | | | | | | | | Implement options in clang to enable recording the driver command-line in an ELF section. Implement a new special named metadata, llvm.commandline, to support frontends embedding their command-line options in IR/ASM/ELF. This differs from the GCC implementation in some key ways: * In GCC there is only one command-line possible per compilation-unit, in LLVM it mirrors llvm.ident and multiple are allowed. * In GCC individual options are separated by NULL bytes, in LLVM entire command-lines are separated by NULL bytes. The advantage of the GCC approach is to clearly delineate options in the face of embedded spaces. The advantage of the LLVM approach is to support merging multiple command-lines unambiguously, while handling embedded spaces with escaping. Differential Revision: https://reviews.llvm.org/D54487 Clang Differential Revision: https://reviews.llvm.org/D54489 llvm-svn: 349155
* [Driver] Add support for -fembed-bitcode for assembly fileSteven Wu2018-12-121-0/+5
| | | | | | | | | | | | | | | | | | Summary: Handle -fembed-bitcode for assembly inputs. When the input file is assembly, write a marker as "__LLVM,__asm" section. Fix llvm.org/pr39659 Reviewers: compnerd, dexonsmith Reviewed By: compnerd Subscribers: rjmccall, dblaikie, jkorous, cfe-commits Differential Revision: https://reviews.llvm.org/D55525 llvm-svn: 348943
* [CUDA][OPENMP][NVPTX]Improve logic of the debug info support.Alexey Bataev2018-12-121-0/+3
| | | | | | | | | | | | | | | | | | | | | | Summary: Added support for the -gline-directives-only option + fixed logic of the debug info for CUDA devices. If optimization level is O0, then options --[no-]cuda-noopt-device-debug do not affect the debug info level. If the optimization level is >O0, debug info options are used + --no-cuda-noopt-device-debug is used or no --cuda-noopt-device-debug is used, the optimization level for the device code is kept and the emission of the debug directives is used. If the opt level is > O0, debug info is requested + --cuda-noopt-device-debug option is used, the optimization is disabled for the device code + required debug info is emitted. Reviewers: tra, echristo Subscribers: aprantl, guansong, JDevlieghere, cfe-commits Differential Revision: https://reviews.llvm.org/D51554 llvm-svn: 348930
* Convert some ObjC msgSends to runtime calls.Pete Cooper2018-12-081-0/+12
| | | | | | | | | | | | | | It is faster to directly call the ObjC runtime for methods such as alloc/allocWithZone instead of sending a message to those functions. This patch adds support for converting messages to alloc/allocWithZone to their equivalent runtime calls. Tests included for the positive case of applying this transformation, negative tests that we ensure we only convert "alloc" to objc_alloc, not "alloc2", and also a driver test to ensure we enable this only for supported runtime versions. Reviewed By: rjmccall https://reviews.llvm.org/D55349 llvm-svn: 348687
* Allow forwarding -fdebug-compilation-dir to cc1asNico Weber2018-12-061-0/+3
| | | | | | | | | | | | | | | | | | | The flag -fdebug-compilation-dir is useful to make generated .o files independent of the path of the build directory, without making the compile command-line dependent on the path of the build directory, like -fdebug-prefix-map requires. This change makes it so that the driver can forward the flag to -cc1as, like it already can for -cc1. We might want to consider making -fdebug-compilation-dir a driver flag in a follow-up. (Since -fdebug-compilation-dir defaults to PWD, it's already possible to get this effect by setting PWD, but explicit compiler flags are better than env vars, because e.g. ninja tracks command lines and reruns commands that change.) Somewhat related to PR14625. Differential Revision: https://reviews.llvm.org/D55377 llvm-svn: 348515
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