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* [ReleaseNotes] MemorySanitizer support of ASLR on FreeBSDDavid Carlier2019-08-271-0/+3
| | | | | | | | | | Reviewers: sylvestre.ledru, kcc Reviewed By: sylvestre.ledru Differential Revision: https://reviews.llvm.org/D66792 llvm-svn: 370035
* Fix -dA flag, it is not a preprocessor flag.Erich Keane2019-08-261-3/+1
| | | | | | | | | -dA was in the d_group, which is a preprocessor state dumping group. However -dA is a debug flag to cause a verbose asm. It was already implemented to do the same thing as -fverbose-asm, so make it just be an alias. llvm-svn: 369926
* [Docs][OpenCL] Several corrections to C++ for OpenCLAnastasia Stulova2019-08-232-63/+74
| | | | | | Differential Revision:https://reviews.llvm.org/D64418 llvm-svn: 369749
* Improve the documentation for OpenCL vector types.Aaron Ballman2019-08-221-3/+3
| | | | | | This fixes some minor grammatical issues I noticed when reading the docs, and changes the recommended feature testing approach to use __has_attribute instead of __has_extension. llvm-svn: 369687
* Revert r369402 "win: Enable /Zc:twoPhase by default if targeting MSVC 2017 ↵Hans Wennborg2019-08-221-3/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | update 3 or newer" This broke compiling some ASan tests with never versions of MSVC/the Win SDK, see https://crbug.com/996675 > MSVC 2017 update 3 (_MSC_VER 1911) enables /Zc:twoPhase by default, and > so should clang-cl: > https://docs.microsoft.com/en-us/cpp/build/reference/zc-twophase > > clang-cl takes the MSVC version it emulates from the -fmsc-version flag, > or if that's not passed it tries to check what the installed version of > MSVC is and uses that, and failing that it uses a default version that's > currently 1911. So this changes the default if no -fmsc-version flag is > passed and no installed MSVC is detected. (It also changes the default > if -fmsc-version is passed or MSVC is detected, and either indicates > _MSC_VER >= 1911.) > > As mentioned in the MSDN article, the Windows SDK header files in > version 10.0.15063.0 (Creators Update or Redstone 2) and earlier > versions do not work correctly with /Zc:twoPhase. If you need to use > these old SDKs with a new clang-cl, explicitly pass /Zc:twoPhase- to get > the old behavior. > > Fixes PR43032. > > Differential Revision: https://reviews.llvm.org/D66394 llvm-svn: 369647
* [PPC Docs] Remove duplicate info about __builtin_setrnd()David Zarzycki2019-08-211-49/+1
| | | | | | | This looks like a combination of a copy-and-paste (and paste and paste) error and a commit without reviewing the diff first error. llvm-svn: 369496
* win: Enable /Zc:twoPhase by default if targeting MSVC 2017 update 3 or newerNico Weber2019-08-201-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | MSVC 2017 update 3 (_MSC_VER 1911) enables /Zc:twoPhase by default, and so should clang-cl: https://docs.microsoft.com/en-us/cpp/build/reference/zc-twophase clang-cl takes the MSVC version it emulates from the -fmsc-version flag, or if that's not passed it tries to check what the installed version of MSVC is and uses that, and failing that it uses a default version that's currently 1911. So this changes the default if no -fmsc-version flag is passed and no installed MSVC is detected. (It also changes the default if -fmsc-version is passed or MSVC is detected, and either indicates _MSC_VER >= 1911.) As mentioned in the MSDN article, the Windows SDK header files in version 10.0.15063.0 (Creators Update or Redstone 2) and earlier versions do not work correctly with /Zc:twoPhase. If you need to use these old SDKs with a new clang-cl, explicitly pass /Zc:twoPhase- to get the old behavior. Fixes PR43032. Differential Revision: https://reviews.llvm.org/D66394 llvm-svn: 369402
* [clang-format] Fix a bug that joins template closer and =Owen Pan2019-08-181-2/+2
| | | | | | | | | | Also fixes the documentation for SpaceBeforeAssignmentOperators. See discussions at https://reviews.llvm.org/D66332 Differential Revision: https://reviews.llvm.org/D66384 llvm-svn: 369214
* [doc] Fix some minor formatting issues.Richard Smith2019-08-161-7/+7
| | | | llvm-svn: 369161
* [Test Commit] Fix typo in diagtool.rstTroy A. Johnson2019-08-161-1/+1
| | | | | | Test commit after obtaining commit access. llvm-svn: 369148
* Fix typos in LibASTImporter.rstGabor Marton2019-08-161-2/+2
| | | | llvm-svn: 369099
* [analyzer] Add docs for cplusplus.InnerPointerKristof Umann2019-08-151-2/+27
| | | | | | Differential Revision: https://reviews.llvm.org/D60281 llvm-svn: 368979
* Document clang-cpp in the release notes for clangChris Bieneman2019-08-141-1/+9
| | | | | | This patch adds a line in the release notes about the new clang-cpp library and the CMake option to force clang to link against it. llvm-svn: 368874
* Add __has_builtin support for builtin function-like type traits.Richard Smith2019-08-141-65/+180
| | | | | | | | | | | | | | | | | | | | | | | | Summary: Previously __has_builtin(__builtin_*) would return false for __builtin_*s that we modeled as keywords rather than as functions (because they take type arguments). With this patch, all builtins that are called with function-call-like syntax return true from __has_builtin (covering __builtin_* and also the __is_* and __has_* type traits and the handful of similar builtins without such a prefix). Update the documentation on __has_builtin and on type traits to match. While doing this I noticed the type trait documentation was out of date and incomplete; that's fixed here too. Reviewers: aaron.ballman Subscribers: jfb, kristina, cfe-commits Tags: #clang Differential Revision: https://reviews.llvm.org/D66100 llvm-svn: 368785
* [clang] Update isDerivedFrom to support Objective-C classes 🔍Stephane Moore2019-08-121-9/+88
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: This change updates `isDerivedFrom` to support Objective-C classes by converting it to a polymorphic matcher. Notes: The matching behavior for Objective-C classes is modeled to match the behavior of `isDerivedFrom` with C++ classes. To that effect, `isDerivedFrom` matches aliased types of derived Objective-C classes, including compatibility aliases. To achieve this, the AST visitor has been updated to map compatibility aliases to their underlying Objective-C class. `isSameOrDerivedFrom` also provides similar behaviors for C++ and Objective-C classes. The behavior that `cxxRecordDecl(isSameOrDerivedFrom("X"))` does not match `class Y {}; typedef Y X;` is mirrored for Objective-C in that `objcInterfaceDecl(isSameOrDerivedFrom("X"))` does not match either `@interface Y @end typedef Y X;` or `@interface Y @end @compatibility_alias X Y;`. Test Notes: Ran clang unit tests. Reviewers: aaron.ballman, jordan_rose, rjmccall, klimek, alexfh, gribozavr Reviewed By: aaron.ballman, gribozavr Subscribers: cfe-commits Tags: #clang Differential Revision: https://reviews.llvm.org/D60543 llvm-svn: 368632
* [CrossTU] User docs: remove temporary limiation with macro expansionGabor Marton2019-08-121-9/+0
| | | | | | D65064, D64635, D64638 pathces solve the issue with macor expansion. llvm-svn: 368562
* [clang-format] Expand AllowShortBlocksOnASingleLine for WebKitOwen Pan2019-08-111-3/+35
| | | | | | | | See PR40840 Differential Revision: https://reviews.llvm.org/D66059 llvm-svn: 368539
* [clang-format] Add SpaceInEmptyBlock option for WebKitOwen Pan2019-08-101-32/+41
| | | | | | | | See PR40840 Differential Revision: https://reviews.llvm.org/D65925 llvm-svn: 368507
* cfi-icall: Allow the jump table to be optionally made non-canonical.Peter Collingbourne2019-08-091-0/+48
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The default behavior of Clang's indirect function call checker will replace the address of each CFI-checked function in the output file's symbol table with the address of a jump table entry which will pass CFI checks. We refer to this as making the jump table `canonical`. This property allows code that was not compiled with ``-fsanitize=cfi-icall`` to take a CFI-valid address of a function, but it comes with a couple of caveats that are especially relevant for users of cross-DSO CFI: - There is a performance and code size overhead associated with each exported function, because each such function must have an associated jump table entry, which must be emitted even in the common case where the function is never address-taken anywhere in the program, and must be used even for direct calls between DSOs, in addition to the PLT overhead. - There is no good way to take a CFI-valid address of a function written in assembly or a language not supported by Clang. The reason is that the code generator would need to insert a jump table in order to form a CFI-valid address for assembly functions, but there is no way in general for the code generator to determine the language of the function. This may be possible with LTO in the intra-DSO case, but in the cross-DSO case the only information available is the function declaration. One possible solution is to add a C wrapper for each assembly function, but these wrappers can present a significant maintenance burden for heavy users of assembly in addition to adding runtime overhead. For these reasons, we provide the option of making the jump table non-canonical with the flag ``-fno-sanitize-cfi-canonical-jump-tables``. When the jump table is made non-canonical, symbol table entries point directly to the function body. Any instances of a function's address being taken in C will be replaced with a jump table address. This scheme does have its own caveats, however. It does end up breaking function address equality more aggressively than the default behavior, especially in cross-DSO mode which normally preserves function address equality entirely. Furthermore, it is occasionally necessary for code not compiled with ``-fsanitize=cfi-icall`` to take a function address that is valid for CFI. For example, this is necessary when a function's address is taken by assembly code and then called by CFI-checking C code. The ``__attribute__((cfi_jump_table_canonical))`` attribute may be used to make the jump table entry of a specific function canonical so that the external code will end up taking a address for the function that will pass CFI checks. Fixes PR41972. Differential Revision: https://reviews.llvm.org/D65629 llvm-svn: 368495
* [clang] Update `ignoringElidableConstructorCall` matcher to ignore ↵Yitzhak Mandelbaum2019-08-081-11/+10
| | | | | | | | | | | | | | | | | | | `ExprWithCleanups`. Summary: The `ExprWithCleanups` node is added to the AST along with the elidable CXXConstructExpr. If it is the outermost node of the node being matched, ignore it as well. Reviewers: gribozavr Subscribers: cfe-commits Tags: #clang Differential Revision: https://reviews.llvm.org/D65944 llvm-svn: 368319
* [clang][NFC] Fix typo in matcher commentYitzhak Mandelbaum2019-08-071-1/+1
| | | | | | Also updates corresponding html doc. llvm-svn: 368188
* Add User docs for ASTImporterGabor Marton2019-08-062-0/+614
| | | | | | | | | | | | | | | | | Summary: This document includes the description of the ASTImporter from the user/client perspective. A subsequent patch will describe the development internals. Reviewers: a_sidorin, shafik, gamesh411, balazske, a.sidorin Subscribers: rnkovacs, dkrupp, arphaman, Szelethus, cfe-commits Tags: #clang Differential Revision: https://reviews.llvm.org/D65573 llvm-svn: 368009
* [docs] don't use :option: for Wall WextraJF Bastien2019-08-051-7/+7
| | | | | | The bots are sad that they're not documented. llvm-svn: 367918
* [docs] don't use :option: for C++ compatJF Bastien2019-08-051-2/+2
| | | | | | The bots are sad that they're not documented. llvm-svn: 367914
* [docs] document -Weveything more bettererJF Bastien2019-08-051-7/+18
| | | | | | | | | | | | Reviewers: aaron.ballman Subscribers: jkorous, dexonsmith, cfe-commits Tags: #clang Differential Revision: https://reviews.llvm.org/D65706 llvm-svn: 367889
* [NFC] Remove LLVM_ALIGNASJF Bastien2019-07-311-1/+1
| | | | | | | | | | | | | | Summary: The minimum compilers support all have alignas, and we don't use LLVM_ALIGNAS anywhere anymore. This also removes an MSVC diagnostic which, according to the comment above, isn't relevant anymore. Reviewers: rnk Subscribers: mgorny, jkorous, dexonsmith, cfe-commits, llvm-commits Tags: #clang, #llvm Differential Revision: https://reviews.llvm.org/D65458 llvm-svn: 367383
* [docs] Add a note about where UBSan emits logsVedant Kumar2019-07-291-0/+6
| | | | llvm-svn: 367270
* doc: Fix Google C++ Style Guide link.Rafael Stahl2019-07-291-1/+1
| | | | llvm-svn: 367219
* [clang] Add isDirectlyDerivedFrom AST matcher.Anton Bikineev2019-07-251-0/+25
| | | | | | Differential Revision: https://reviews.llvm.org/D65092 llvm-svn: 367010
* [OpenCL] Rename lang mode flag for C++ modeAnastasia Stulova2019-07-252-3/+3
| | | | | | | | | | | | Rename lang mode flag to -cl-std=clc++/-cl-std=CLC++ or -std=clc++/-std=CLC++. This aligns with OpenCL C conversion and removes ambiguity with OpenCL C++. Differential Revision: https://reviews.llvm.org/D65102 llvm-svn: 367008
* [Clang] New loop pragma vectorize_predicateSjoerd Meijer2019-07-251-3/+18
| | | | | | | | | | | | | | | | | | | This adds a new vectorize predication loop hint: #pragma clang loop vectorize_predicate(enable) that can be used to indicate to the vectoriser that all (load/store) instructions should be predicated (masked). This allows, for example, folding of the remainder loop into the main loop. This patch will be followed up with D64916 and D65197. The former is a refactoring in the loopvectorizer and the groundwork to make tail loop folding a more general concept, and in the latter the actual tail loop folding transformation will be implemented. Differential Revision: https://reviews.llvm.org/D64744 llvm-svn: 366989
* [Support] Fix `-ftime-trace-granularity` optionAnton Afanasyev2019-07-241-0/+8
| | | | | | | | | | | | | | | | Summary: Move `-ftime-trace-granularity` option to frontend options. Without patch this option is showed up in the help for any tool that links libSupport. Reviewers: sammccall Subscribers: hiraditya, cfe-commits, llvm-commits Tags: #clang, #llvm Differential Revision: https://reviews.llvm.org/D65202 llvm-svn: 366911
* [analyzer] Add CTU user docsGabor Marton2019-07-182-0/+207
| | | | | | | | | | | | Reviewers: dkrupp, a_sidorin, Szelethus, NoQ Subscribers: whisperity, xazax.hun, baloghadamsoftware, szepet, rnkovacs, a.sidorin, mikhail.ramalho, donat.nagy, gamesh411, Charusso, cfe-commits Tags: #clang Differential Revision: https://reviews.llvm.org/D64801 llvm-svn: 366439
* Bump the trunk version to 10.0.0svnHans Wennborg2019-07-182-53/+18
| | | | | | and clear the release notes. llvm-svn: 366427
* [Docs][OpenCL] Documentation of C++ for OpenCL modeAnastasia Stulova2019-07-172-1/+310
| | | | | | | | | Added documentation of C++ for OpenCL mode into Clang User Manual and Language Extensions document. Differential Revision: https://reviews.llvm.org/D64418 llvm-svn: 366351
* Finish "Adapt -fsanitize=function to SANITIZER_NON_UNIQUE_TYPEINFO"Stephan Bergmann2019-07-161-2/+2
| | | | | | | | | | | | | | | | | | | | | i.e., recent 5745eccef54ddd3caca278d1d292a88b2281528b: * Bump the function_type_mismatch handler version, as its signature has changed. * The function_type_mismatch handler can return successfully now, so SanitizerKind::Function must be AlwaysRecoverable (like for SanitizerKind::Vptr). * But the minimal runtime would still unconditionally treat a call to the function_type_mismatch handler as failure, so disallow -fsanitize=function in combination with -fsanitize-minimal-runtime (like it was already done for -fsanitize=vptr). * Add tests. Differential Revision: https://reviews.llvm.org/D61479 llvm-svn: 366186
* Update __VERSION__ to remove the hardcoded 4.2.1 versionSylvestre Ledru2019-07-152-0/+8
| | | | | | | | | | | | | | | | | | Summary: Just like in https://reviews.llvm.org/D56803 for -dumpversion Reviewers: rnk Reviewed By: rnk Subscribers: dexonsmith, lebedev.ri, hubert.reinterpretcast, xbolva00, fedor.sergeev, cfe-commits Tags: #clang Differential Revision: https://reviews.llvm.org/D63048 llvm-svn: 366091
* Support __seg_fs and __seg_gs on x86JF Bastien2019-07-141-0/+4
| | | | | | | | | | | | | | | | | | | | | Summary: GCC supports named address spaces macros: https://gcc.gnu.org/onlinedocs/gcc/Named-Address-Spaces.html clang does as well with address spaces: https://clang.llvm.org/docs/LanguageExtensions.html#memory-references-to-specified-segments Add the __seg_fs and __seg_gs macros for compatibility with GCC. <rdar://problem/52944935> Subscribers: jkorous, dexonsmith, cfe-commits Tags: #clang Differential Revision: https://reviews.llvm.org/D64676 llvm-svn: 366028
* consistency in the release notesSylvestre Ledru2019-07-141-2/+2
| | | | llvm-svn: 366024
* This reverts commit 632a36bfcfc8273c1861f04ff6758d863c47c784.Sylvestre Ledru2019-07-132-12/+0
| | | | | | | | | | | | Some targets such as Python 2.7.16 still use VERSION in their builds. Without VERSION defined, the source code has syntax errors. Reverting as it will probably break many other things. Noticed by Sterling Augustine llvm-svn: 365992
* Remove __VERSION__Sylvestre Ledru2019-07-122-0/+12
| | | | | | | | | | | | | | | | | | | | Summary: It has been introduced in 2011 for gcc compat: https://github.com/llvm-mirror/clang/commit/ad1a4c6e89594e704775ddb6b036ac982fd68cad it is probably time to remove it Reviewers: rnk, dexonsmith Reviewed By: rnk Subscribers: dschuff, aheejin, fedor.sergeev, arphaman, cfe-commits Tags: #clang Differential Revision: https://reviews.llvm.org/D64062 llvm-svn: 365962
* [Driver] -noprofilelib flagPetr Hosek2019-07-111-0/+2
| | | | | | | | | | This flag is analoguous to other flags like -nostdlib or -nolibc and could be used to disable linking of profile runtime library. This is useful in certain environments like kernel, where profile instrumentation is still desirable, but we cannot use the standard runtime library. llvm-svn: 365808
* [Docs] Add standardized header links to analyzer docNathan Huckleberry2019-07-111-0/+268
| | | | | | | | | | | | | | | | | | | | | | | Summary: Header links should have some standard form so clang tidy docs can easily reference them. The form is as follows. Start with the analyzer full name including packages. Replace all periods with dashes and lowercase everything. Ex: core.CallAndMessage -> core-callandmessage Reviewers: JonasToth, aaron.ballman, NoQ, Szelethus Reviewed By: aaron.ballman, Szelethus Subscribers: nickdesaulniers, lebedev.ri, baloghadamsoftware, mgrang, a.sidorin, Szelethus, jfb, donat.nagy, dkrupp, cfe-commits Tags: #clang Differential Revision: https://reviews.llvm.org/D64543 llvm-svn: 365797
* [analyzer]Add user docs rstGabor Marton2019-07-102-3/+8
| | | | | | | | | | | | | | | | Summary: Add user documentation page. This is an empty page atm, later patches will add the specific user documentatoins. Reviewers: dkrupp Subscribers: whisperity, xazax.hun, baloghadamsoftware, szepet, rnkovacs, a.sidorin, mikhail.ramalho, Szelethus, donat.nagy, gamesh411, Charusso, cfe-commits Tags: #clang Differential Revision: https://reviews.llvm.org/D64494 llvm-svn: 365639
* hwasan: Improve precision of checks using short granule tags.Peter Collingbourne2019-07-091-12/+52
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | A short granule is a granule of size between 1 and `TG-1` bytes. The size of a short granule is stored at the location in shadow memory where the granule's tag is normally stored, while the granule's actual tag is stored in the last byte of the granule. This means that in order to verify that a pointer tag matches a memory tag, HWASAN must check for two possibilities: * the pointer tag is equal to the memory tag in shadow memory, or * the shadow memory tag is actually a short granule size, the value being loaded is in bounds of the granule and the pointer tag is equal to the last byte of the granule. Pointer tags between 1 to `TG-1` are possible and are as likely as any other tag. This means that these tags in memory have two interpretations: the full tag interpretation (where the pointer tag is between 1 and `TG-1` and the last byte of the granule is ordinary data) and the short tag interpretation (where the pointer tag is stored in the granule). When HWASAN detects an error near a memory tag between 1 and `TG-1`, it will show both the memory tag and the last byte of the granule. Currently, it is up to the user to disambiguate the two possibilities. Because this functionality obsoletes the right aligned heap feature of the HWASAN memory allocator (and because we can no longer easily test it), the feature is removed. Also update the documentation to cover both short granule tags and outlined checks. Differential Revision: https://reviews.llvm.org/D63908 llvm-svn: 365551
* Remove trailing whitespaces in the Language Extensions docSylvestre Ledru2019-07-091-13/+13
| | | | llvm-svn: 365446
* Add AlignConsecutiveMacros to the clang release notesSylvestre Ledru2019-07-091-0/+2
| | | | llvm-svn: 365445
* [BPF] Preserve debuginfo array/union/struct type/access indexYonghong Song2019-07-091-0/+29
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | For background of BPF CO-RE project, please refer to http://vger.kernel.org/bpfconf2019.html In summary, BPF CO-RE intends to compile bpf programs adjustable on struct/union layout change so the same program can run on multiple kernels with adjustment before loading based on native kernel structures. In order to do this, we need keep track of GEP(getelementptr) instruction base and result debuginfo types, so we can adjust on the host based on kernel BTF info. Capturing such information as an IR optimization is hard as various optimization may have tweaked GEP and also union is replaced by structure it is impossible to track fieldindex for union member accesses. Three intrinsic functions, preserve_{array,union,struct}_access_index, are introducted. addr = preserve_array_access_index(base, index, dimension) addr = preserve_union_access_index(base, di_index) addr = preserve_struct_access_index(base, gep_index, di_index) here, base: the base pointer for the array/union/struct access. index: the last access index for array, the same for IR/DebugInfo layout. dimension: the array dimension. gep_index: the access index based on IR layout. di_index: the access index based on user/debuginfo types. If using these intrinsics blindly, i.e., transforming all GEPs to these intrinsics and later on reducing them to GEPs, we have seen up to 7% more instructions generated. To avoid such an overhead, a clang builtin is proposed: base = __builtin_preserve_access_index(base) such that user wraps to-be-relocated GEPs in this builtin and preserve_*_access_index intrinsics only apply to those GEPs. Such a buyin will prevent performance degradation if people do not use CO-RE, even for programs which use bpf_probe_read(). For example, for the following example, $ cat test.c struct sk_buff { int i; int b1:1; int b2:2; union { struct { int o1; int o2; } o; struct { char flags; char dev_id; } dev; int netid; } u[10]; }; static int (*bpf_probe_read)(void *dst, int size, const void *unsafe_ptr) = (void *) 4; #define _(x) (__builtin_preserve_access_index(x)) int bpf_prog(struct sk_buff *ctx) { char dev_id; bpf_probe_read(&dev_id, sizeof(char), _(&ctx->u[5].dev.dev_id)); return dev_id; } $ clang -target bpf -O2 -g -emit-llvm -S -mllvm -print-before-all \ test.c >& log The generated IR looks like below: ... define dso_local i32 @bpf_prog(%struct.sk_buff*) #0 !dbg !15 { %2 = alloca %struct.sk_buff*, align 8 %3 = alloca i8, align 1 store %struct.sk_buff* %0, %struct.sk_buff** %2, align 8, !tbaa !45 call void @llvm.dbg.declare(metadata %struct.sk_buff** %2, metadata !43, metadata !DIExpression()), !dbg !49 call void @llvm.lifetime.start.p0i8(i64 1, i8* %3) #4, !dbg !50 call void @llvm.dbg.declare(metadata i8* %3, metadata !44, metadata !DIExpression()), !dbg !51 %4 = load i32 (i8*, i32, i8*)*, i32 (i8*, i32, i8*)** @bpf_probe_read, align 8, !dbg !52, !tbaa !45 %5 = load %struct.sk_buff*, %struct.sk_buff** %2, align 8, !dbg !53, !tbaa !45 %6 = call [10 x %union.anon]* @llvm.preserve.struct.access.index.p0a10s_union.anons.p0s_struct.sk_buffs( %struct.sk_buff* %5, i32 2, i32 3), !dbg !53, !llvm.preserve.access.index !19 %7 = call %union.anon* @llvm.preserve.array.access.index.p0s_union.anons.p0a10s_union.anons( [10 x %union.anon]* %6, i32 1, i32 5), !dbg !53 %8 = call %union.anon* @llvm.preserve.union.access.index.p0s_union.anons.p0s_union.anons( %union.anon* %7, i32 1), !dbg !53, !llvm.preserve.access.index !26 %9 = bitcast %union.anon* %8 to %struct.anon.0*, !dbg !53 %10 = call i8* @llvm.preserve.struct.access.index.p0i8.p0s_struct.anon.0s( %struct.anon.0* %9, i32 1, i32 1), !dbg !53, !llvm.preserve.access.index !34 %11 = call i32 %4(i8* %3, i32 1, i8* %10), !dbg !52 %12 = load i8, i8* %3, align 1, !dbg !54, !tbaa !55 %13 = sext i8 %12 to i32, !dbg !54 call void @llvm.lifetime.end.p0i8(i64 1, i8* %3) #4, !dbg !56 ret i32 %13, !dbg !57 } !19 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "sk_buff", file: !3, line: 1, size: 704, elements: !20) !26 = distinct !DICompositeType(tag: DW_TAG_union_type, scope: !19, file: !3, line: 5, size: 64, elements: !27) !34 = distinct !DICompositeType(tag: DW_TAG_structure_type, scope: !26, file: !3, line: 10, size: 16, elements: !35) Note that @llvm.preserve.{struct,union}.access.index calls have metadata llvm.preserve.access.index attached to instructions to provide struct/union debuginfo type information. For &ctx->u[5].dev.dev_id, . The "%6 = ..." represents struct member "u" with index 2 for IR layout and index 3 for DI layout. . The "%7 = ..." represents array subscript "5". . The "%8 = ..." represents union member "dev" with index 1 for DI layout. . The "%10 = ..." represents struct member "dev_id" with index 1 for both IR and DI layout. Basically, traversing the use-def chain recursively for the 3rd argument of bpf_probe_read() and examining all preserve_*_access_index calls, the debuginfo struct/union/array access index can be achieved. The intrinsics also contain enough information to regenerate codes for IR layout. For array and structure intrinsics, the proper GEP can be constructed. For union intrinsics, replacing all uses of "addr" with "base" should be enough. Signed-off-by: Yonghong Song <yhs@fb.com> Differential Revision: https://reviews.llvm.org/D61809 llvm-svn: 365438
* Revert "[BPF] Preserve debuginfo array/union/struct type/access index"Yonghong Song2019-07-091-29/+0
| | | | | | | | | This reverts commit r365435. Forgot adding the Differential Revision link. Will add to the commit message and resubmit. llvm-svn: 365436
* [BPF] Preserve debuginfo array/union/struct type/access indexYonghong Song2019-07-091-0/+29
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | For background of BPF CO-RE project, please refer to http://vger.kernel.org/bpfconf2019.html In summary, BPF CO-RE intends to compile bpf programs adjustable on struct/union layout change so the same program can run on multiple kernels with adjustment before loading based on native kernel structures. In order to do this, we need keep track of GEP(getelementptr) instruction base and result debuginfo types, so we can adjust on the host based on kernel BTF info. Capturing such information as an IR optimization is hard as various optimization may have tweaked GEP and also union is replaced by structure it is impossible to track fieldindex for union member accesses. Three intrinsic functions, preserve_{array,union,struct}_access_index, are introducted. addr = preserve_array_access_index(base, index, dimension) addr = preserve_union_access_index(base, di_index) addr = preserve_struct_access_index(base, gep_index, di_index) here, base: the base pointer for the array/union/struct access. index: the last access index for array, the same for IR/DebugInfo layout. dimension: the array dimension. gep_index: the access index based on IR layout. di_index: the access index based on user/debuginfo types. If using these intrinsics blindly, i.e., transforming all GEPs to these intrinsics and later on reducing them to GEPs, we have seen up to 7% more instructions generated. To avoid such an overhead, a clang builtin is proposed: base = __builtin_preserve_access_index(base) such that user wraps to-be-relocated GEPs in this builtin and preserve_*_access_index intrinsics only apply to those GEPs. Such a buyin will prevent performance degradation if people do not use CO-RE, even for programs which use bpf_probe_read(). For example, for the following example, $ cat test.c struct sk_buff { int i; int b1:1; int b2:2; union { struct { int o1; int o2; } o; struct { char flags; char dev_id; } dev; int netid; } u[10]; }; static int (*bpf_probe_read)(void *dst, int size, const void *unsafe_ptr) = (void *) 4; #define _(x) (__builtin_preserve_access_index(x)) int bpf_prog(struct sk_buff *ctx) { char dev_id; bpf_probe_read(&dev_id, sizeof(char), _(&ctx->u[5].dev.dev_id)); return dev_id; } $ clang -target bpf -O2 -g -emit-llvm -S -mllvm -print-before-all \ test.c >& log The generated IR looks like below: ... define dso_local i32 @bpf_prog(%struct.sk_buff*) #0 !dbg !15 { %2 = alloca %struct.sk_buff*, align 8 %3 = alloca i8, align 1 store %struct.sk_buff* %0, %struct.sk_buff** %2, align 8, !tbaa !45 call void @llvm.dbg.declare(metadata %struct.sk_buff** %2, metadata !43, metadata !DIExpression()), !dbg !49 call void @llvm.lifetime.start.p0i8(i64 1, i8* %3) #4, !dbg !50 call void @llvm.dbg.declare(metadata i8* %3, metadata !44, metadata !DIExpression()), !dbg !51 %4 = load i32 (i8*, i32, i8*)*, i32 (i8*, i32, i8*)** @bpf_probe_read, align 8, !dbg !52, !tbaa !45 %5 = load %struct.sk_buff*, %struct.sk_buff** %2, align 8, !dbg !53, !tbaa !45 %6 = call [10 x %union.anon]* @llvm.preserve.struct.access.index.p0a10s_union.anons.p0s_struct.sk_buffs( %struct.sk_buff* %5, i32 2, i32 3), !dbg !53, !llvm.preserve.access.index !19 %7 = call %union.anon* @llvm.preserve.array.access.index.p0s_union.anons.p0a10s_union.anons( [10 x %union.anon]* %6, i32 1, i32 5), !dbg !53 %8 = call %union.anon* @llvm.preserve.union.access.index.p0s_union.anons.p0s_union.anons( %union.anon* %7, i32 1), !dbg !53, !llvm.preserve.access.index !26 %9 = bitcast %union.anon* %8 to %struct.anon.0*, !dbg !53 %10 = call i8* @llvm.preserve.struct.access.index.p0i8.p0s_struct.anon.0s( %struct.anon.0* %9, i32 1, i32 1), !dbg !53, !llvm.preserve.access.index !34 %11 = call i32 %4(i8* %3, i32 1, i8* %10), !dbg !52 %12 = load i8, i8* %3, align 1, !dbg !54, !tbaa !55 %13 = sext i8 %12 to i32, !dbg !54 call void @llvm.lifetime.end.p0i8(i64 1, i8* %3) #4, !dbg !56 ret i32 %13, !dbg !57 } !19 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "sk_buff", file: !3, line: 1, size: 704, elements: !20) !26 = distinct !DICompositeType(tag: DW_TAG_union_type, scope: !19, file: !3, line: 5, size: 64, elements: !27) !34 = distinct !DICompositeType(tag: DW_TAG_structure_type, scope: !26, file: !3, line: 10, size: 16, elements: !35) Note that @llvm.preserve.{struct,union}.access.index calls have metadata llvm.preserve.access.index attached to instructions to provide struct/union debuginfo type information. For &ctx->u[5].dev.dev_id, . The "%6 = ..." represents struct member "u" with index 2 for IR layout and index 3 for DI layout. . The "%7 = ..." represents array subscript "5". . The "%8 = ..." represents union member "dev" with index 1 for DI layout. . The "%10 = ..." represents struct member "dev_id" with index 1 for both IR and DI layout. Basically, traversing the use-def chain recursively for the 3rd argument of bpf_probe_read() and examining all preserve_*_access_index calls, the debuginfo struct/union/array access index can be achieved. The intrinsics also contain enough information to regenerate codes for IR layout. For array and structure intrinsics, the proper GEP can be constructed. For union intrinsics, replacing all uses of "addr" with "base" should be enough. Signed-off-by: Yonghong Song <yhs@fb.com> llvm-svn: 365435
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