llvm-project/clang/lib/AST
Roman Lebedev 3dd5a298bf
[clang] Annotating C++'s `operator new` with more attributes
Summary:
Right now we annotate C++'s `operator new` with `noalias` attribute,
which very much is healthy for optimizations.

However as per [[ http://eel.is/c++draft/basic.stc.dynamic.allocation | `[basic.stc.dynamic.allocation]` ]],
there are more promises on global `operator new`, namely:
* non-`std::nothrow_t` `operator new` *never* returns `nullptr`
* If `std::align_val_t align` parameter is taken, the pointer will also be `align`-aligned
* ~~global `operator new`-returned pointer is `__STDCPP_DEFAULT_NEW_ALIGNMENT__`-aligned ~~ It's more caveated than that.

Supplying this information may not cause immediate landslide effects
on any specific benchmarks, but it for sure will be healthy for optimizer
in the sense that the IR will better reflect the guarantees provided in the source code.

The caveat is `-fno-assume-sane-operator-new`, which currently prevents emitting `noalias`
attribute, and is automatically passed by Sanitizers ([[ https://bugs.llvm.org/show_bug.cgi?id=16386 | PR16386 ]]) - should it also cover these attributes?
The problem is that the flag is back-end-specific, as seen in `test/Modules/explicit-build-flags.cpp`.
But while it is okay to add `noalias` metadata in backend, we really should be adding at least
the alignment metadata to the AST, since that allows us to perform sema checks on it.

Reviewers: erichkeane, rjmccall, jdoerfert, eugenis, rsmith

Reviewed By: rsmith

Subscribers: xbolva00, jrtc27, atanasyan, nlopes, cfe-commits

Tags: #llvm, #clang

Differential Revision: https://reviews.llvm.org/D73380
2020-02-26 01:37:17 +03:00
..
Interp [Clang interpreter] Rename Block.{h,cpp} to InterpBlock.{h,cpp} 2020-02-21 09:47:28 -08:00
APValue.cpp Silence static analyzer getAs<RecordType> null dereference warnings. NFCI. 2019-10-03 11:22:48 +00:00
ASTConcept.cpp [Concepts] Transform constraints of non-template functions to ConstantEvaluated 2020-01-25 23:00:24 +02:00
ASTConsumer.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
ASTContext.cpp [AIX][Frontend] C++ ABI customizations for AIX boilerplate 2020-02-24 10:26:51 -05:00
ASTDiagnostic.cpp Make llvm::StringRef to std::string conversions explicit. 2020-01-28 23:25:25 +01:00
ASTDumper.cpp When dumping the AST to JSON, dump the type information from a typeid expression with a type operand. 2019-05-27 14:34:31 +00:00
ASTImporter.cpp [ASTImporter] Improved variable template redecl chain handling. 2020-02-25 14:48:37 +01:00
ASTImporterLookupTable.cpp [ASTImporter] Fix unhandled cases in ASTImporterLookupTable 2019-06-11 13:35:25 +00:00
ASTStructuralEquivalence.cpp [AST][NFC] Update outdated comments in ASTStructuralEquivalence.cpp 2020-02-21 15:54:58 +01:00
ASTTypeTraits.cpp Remove clang::ast_type_traits namespace in favor of clang 2020-02-13 10:46:47 -08:00
AttrImpl.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
CMakeLists.txt [Clang interpreter] Rename Block.{h,cpp} to InterpBlock.{h,cpp} 2020-02-21 09:47:28 -08:00
CXXABI.h Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
CXXInheritance.cpp Fix wrong devirtualization when the final overrider in one base class 2020-01-31 17:06:48 -08:00
Comment.cpp Fix "pointer is null" static analyzer warning. NFCI. 2020-01-07 13:41:52 +00:00
CommentBriefParser.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
CommentCommandTraits.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
CommentLexer.cpp [AST] CommentLexer - Remove (optional) Invalid parameter from getSpelling. 2019-09-18 12:11:16 +00:00
CommentParser.cpp Adds a warning when an inline Doxygen comment has no argument 2019-08-05 08:05:16 +00:00
CommentSema.cpp [clang][doxygen] Fix false -Wdocumentation warning for tag typedefs 2020-02-20 11:32:30 -08:00
ComparisonCategories.cpp [c++20] P1959R0: Remove support for std::*_equality. 2019-12-16 17:49:45 -08:00
DataCollection.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
Decl.cpp [clang] Annotating C++'s `operator new` with more attributes 2020-02-26 01:37:17 +03:00
DeclBase.cpp Make llvm::StringRef to std::string conversions explicit. 2020-01-28 23:25:25 +01:00
DeclCXX.cpp [NFC] Remove trailing space 2020-02-18 10:49:13 +08:00
DeclFriend.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
DeclGroup.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
DeclObjC.cpp [objc_direct] Tigthen checks for direct methods 2019-12-20 10:57:36 -08:00
DeclOpenMP.cpp [OPENMP 5.0]Initial support for 'allocator' clause. 2019-03-12 18:52:33 +00:00
DeclPrinter.cpp [clang][DeclPrinter] Implement visitors for {TemplateType,NonTypeTemplate}Parms 2020-02-14 13:20:34 +01:00
DeclTemplate.cpp Add missing newlines at EOF; NFC 2020-02-12 15:57:25 +00:00
DeclarationName.cpp [AST] Let DeclarationNameInfo printing use PrintingPolicy, and fix const-correctness 2019-11-15 19:19:41 +01:00
Expr.cpp Fix type-dependency of bitfields in templates 2020-02-12 13:31:41 -08:00
ExprCXX.cpp [Concepts] Requires Expressions 2020-01-19 00:23:26 +02:00
ExprClassification.cpp [Concepts] Requires Expressions 2020-01-19 00:23:26 +02:00
ExprConcepts.cpp [Concept] Fix incorrect check for containsUnexpandedParameterPack in CSE 2020-01-30 20:45:44 +02:00
ExprConstant.cpp P0593R6: Pseudo-destructor expressions end object lifetimes. 2020-02-18 18:41:03 -08:00
ExprObjC.cpp [AST][NFC] Add const children() accessors to all AST nodes 2019-04-12 15:36:02 +00:00
ExternalASTMerger.cpp Modernize llvm::Error handling in ExternalASTMerger 2019-11-14 13:58:32 +01:00
ExternalASTSource.cpp Make llvm::StringRef to std::string conversions explicit. 2020-01-28 23:25:25 +01:00
FormatString.cpp Revert "[Clang] Warn about 'z' printf modifier in old MSVC." 2020-01-28 09:27:54 -05:00
FormatStringParsing.h Add a missing header comment, NFC 2019-08-13 22:01:39 +00:00
InheritViz.cpp Silence static analyzer getAs<RecordType> null dereference warnings. NFCI. 2019-10-03 11:22:48 +00:00
ItaniumCXXABI.cpp [c++20] Fix some ambiguities in our mangling of lambdas with explicit 2019-09-05 01:23:47 +00:00
ItaniumMangle.cpp [Concepts] Requires Expressions 2020-01-19 00:23:26 +02:00
JSONNodeDumper.cpp [NFC] Remove trailing space 2020-02-18 10:49:13 +08:00
Linkage.h [AST] Split parent map traversal logic into ParentMapContext.h 2020-01-24 13:42:28 -08:00
Mangle.cpp Make llvm::StringRef to std::string conversions explicit. 2020-01-28 23:25:25 +01:00
MicrosoftCXXABI.cpp Separate the MS inheritance model enum from the attribute, NFC 2019-11-22 16:06:30 -08:00
MicrosoftMangle.cpp Make llvm::StringRef to std::string conversions explicit. 2020-01-28 23:25:25 +01:00
NSAPI.cpp Removed dead code from clang/AST/NSAPI.h 2019-08-29 06:30:12 +00:00
NestedNameSpecifier.cpp Don't call memcpy(p, 0, 0). 2020-02-13 00:51:12 -08:00
ODRHash.cpp [Concepts] Placeholder constraints and abbreviated templates 2020-01-23 19:39:43 +02:00
OSLog.cpp os_log: Allow specifying mask type in format string. 2018-11-06 07:05:14 +00:00
OpenMPClause.cpp [OpenMP][NFCI] Use the libFrontend DefaultKind in Clang 2020-02-15 00:38:12 -06:00
ParentMap.cpp [OPENMP]Fix PR42632: crash on the analysis of the OpenMP constructs. 2019-07-17 18:03:39 +00:00
ParentMapContext.cpp Remove clang::ast_type_traits namespace in favor of clang 2020-02-13 10:46:47 -08:00
PrintfFormatString.cpp [Sema][ObjC] Fix a -Wformat false positive with localizedStringForKey 2019-08-14 16:57:11 +00:00
QualTypeNames.cpp Fix crash in getFullyQualifiedName for inline namespace 2019-12-28 16:35:51 +03:00
RawCommentList.cpp [clang] Refactor doc comments to Decls attribution 2019-08-13 18:11:44 +00:00
RecordLayout.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
RecordLayoutBuilder.cpp Move vtordisp mode from Attr class to LangOptions.h, NFC 2019-11-22 15:47:46 -08:00
ScanfFormatString.cpp Fix parameter name comments using clang-tidy. NFC. 2019-07-16 04:46:31 +00:00
SelectorLocationsKind.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
Stmt.cpp Support output constraints on "asm goto" 2020-02-24 18:51:29 -08:00
StmtCXX.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
StmtIterator.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
StmtObjC.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
StmtOpenMP.cpp [OPENMP50]Add cancellation support in taskloop-based directives. 2020-02-13 12:03:43 -05:00
StmtPrinter.cpp Make llvm::StringRef to std::string conversions explicit. 2020-01-28 23:25:25 +01:00
StmtProfile.cpp [NFC] Remove trailing space 2020-02-18 10:49:13 +08:00
StmtViz.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
TemplateBase.cpp [Concepts] Placeholder constraints and abbreviated templates 2020-01-23 19:39:43 +02:00
TemplateName.cpp [c++20] Implement P0846R0: allow (ADL-only) calls to template-ids whose 2019-05-09 03:31:27 +00:00
TextNodeDumper.cpp [Concepts] Placeholder constraints and abbreviated templates 2020-01-23 19:39:43 +02:00
Type.cpp [Concepts] Placeholder constraints and abbreviated templates 2020-01-23 19:39:43 +02:00
TypeLoc.cpp [Concepts] Placeholder constraints and abbreviated templates 2020-01-23 19:39:43 +02:00
TypePrinter.cpp Make llvm::StringRef to std::string conversions explicit. 2020-01-28 23:25:25 +01:00
VTTBuilder.cpp Silence static analyzer getAs<RecordType> null dereference warnings. NFCI. 2019-10-03 11:22:48 +00:00
VTableBuilder.cpp List implicit operator== after implicit destructors in a vtable. 2020-01-21 15:54:40 -08:00