llvm-project/clang/lib/CodeGen
Stephan Bergmann 8c85bca5a5 No -fsanitize=function warning when calling noexcept function through non-noexcept pointer in C++17
As discussed in the mail thread <https://groups.google.com/a/isocpp.org/forum/
#!topic/std-discussion/T64_dW3WKUk> "Calling noexcept function throug non-
noexcept pointer is undefined behavior?", such a call should not be UB.
However, Clang currently warns about it.

This change removes exception specifications from the function types recorded
for -fsanitize=function, both in the functions themselves and at the call sites.
That means that calling a non-noexcept function through a noexcept pointer will
also not be flagged as UB.  In the review of this change, that was deemed
acceptable, at least for now.  (See the "TODO" in compiler-rt
test/ubsan/TestCases/TypeCheck/Function/function.cpp.)

To remove exception specifications from types, the existing internal
ASTContext::getFunctionTypeWithExceptionSpec was made public, and some places
otherwise unrelated to this change have been adapted to call it, too.

This is the cfe part of a patch covering both cfe and compiler-rt.

Differential Revision: https://reviews.llvm.org/D40720

llvm-svn: 321859
2018-01-05 07:57:12 +00:00
..
ABIInfo.h Add flag to request Clang is ABI-compatible with older versions of itself 2017-08-26 01:04:35 +00:00
Address.h Work around build failure due to GCC 4.8.1 bug. We don't completely understand 2016-02-02 23:11:49 +00:00
BackendUtil.cpp [hwasan] Implement -fsanitize-recover=hwaddress. 2017-12-20 19:05:44 +00:00
CGAtomic.cpp Silence a bunch of implicit fallthrough warnings 2017-12-19 22:06:11 +00:00
CGBlocks.cpp [Blocks] Inherit sanitizer options from parent decl 2017-12-08 02:47:58 +00:00
CGBlocks.h [CodeGen][ObjC] Block captures should inherit the type of the captured 2016-09-16 00:02:06 +00:00
CGBuilder.h [OpenCL] Handle address space conversion while setting type alignment. 2017-09-27 14:37:00 +00:00
CGBuiltin.cpp [CGBuiltin] Handle unsigned mul overflow properly (PR35750) 2018-01-03 23:11:32 +00:00
CGCUDANV.cpp Suppress all uses of LLVM_END_WITH_NULL. NFC. 2017-05-09 19:31:30 +00:00
CGCUDARuntime.cpp Refactor call emission to package the function pointer together with 2016-10-26 23:46:34 +00:00
CGCUDARuntime.h [CUDA] Emit host-side 'shadows' for device-side global variables 2016-03-02 18:28:50 +00:00
CGCXX.cpp [MS] Don't bail on replacing dllimport vbase dtors with base dtors 2017-10-13 00:53:02 +00:00
CGCXXABI.cpp [MS] Apply adjustments after storing 'this' 2017-11-16 19:09:36 +00:00
CGCXXABI.h IRGen: When performing CFI checks, load vtable pointer from vbase when necessary. 2017-12-13 21:53:04 +00:00
CGCall.cpp Revert "[CodeGen] Fix crash when a function taking transparent union is redeclared." 2017-12-21 20:52:59 +00:00
CGCall.h Use less temporary AttributeLists NFC 2017-04-18 23:50:03 +00:00
CGClass.cpp In an ARC lambda-to-block conversion thunk, reclaim the return value of 2017-12-14 18:21:14 +00:00
CGCleanup.cpp Fix typo in comment, no behavior change. 2017-08-25 18:41:41 +00:00
CGCleanup.h Use the correct ObjC EH personality 2017-01-08 22:58:07 +00:00
CGCoroutine.cpp [coroutines] Support coroutine-handle returning await-suspend (i.e symmetric control transfer) 2017-08-25 04:46:54 +00:00
CGDebugInfo.cpp Debug Info: Support DW_AT_calling_convention on composite types. 2018-01-05 01:13:52 +00:00
CGDebugInfo.h Simplify codegen and debug info generation for block context parameters. 2017-10-26 20:08:52 +00:00
CGDecl.cpp Reland "Fix vtable not receiving hidden visibility when using push(visibility)" 2017-11-29 00:54:20 +00:00
CGDeclCXX.cpp [OPENMP] Support for -fopenmp-simd option with compilation of simd loops 2017-12-29 18:07:07 +00:00
CGException.cpp [WinEH] Allow for multiple terminatepads 2018-01-02 21:34:16 +00:00
CGExpr.cpp No -fsanitize=function warning when calling noexcept function through non-noexcept pointer in C++17 2018-01-05 07:57:12 +00:00
CGExprAgg.cpp Silence a bunch of implicit fallthrough warnings 2017-12-19 22:06:11 +00:00
CGExprCXX.cpp -fsanitize=vptr warnings on bad static types in dynamic_cast and typeid 2017-12-28 12:45:41 +00:00
CGExprComplex.cpp [Complex] Don't use __div?c3 when building with fast-math. 2017-12-20 15:50:52 +00:00
CGExprConstant.cpp [CodeGen][X86] Fix handling of __fp16 vectors. 2017-12-09 00:02:37 +00:00
CGExprScalar.cpp [c++20] P0515R3: Parsing support and basic AST construction for operator <=>. 2017-12-14 15:16:18 +00:00
CGGPUBuiltin.cpp [OpenMP][NVPTX][CUDA] Adding support for printf for an NVPTX OpenMP device. 2017-01-29 20:49:31 +00:00
CGLoopInfo.cpp [CodeGen] Pass objects that are expensive to copy by const ref. 2016-11-24 16:01:20 +00:00
CGLoopInfo.h [CodeGen] Pass objects that are expensive to copy by const ref. 2016-11-24 16:01:20 +00:00
CGObjC.cpp [CodeGen] Do not construct complete LValue base info in trivial cases 2017-10-10 09:39:32 +00:00
CGObjCGNU.cpp Fix CGObjCGNU::init bug introduced by r302572 2017-05-09 21:19:44 +00:00
CGObjCMac.cpp [driver] Set the 'simulator' environment for Darwin when compiling for 2017-12-07 19:04:10 +00:00
CGObjCRuntime.cpp [CodeGen] Propagate may-alias'ness of lvalues with TBAA info 2017-10-31 11:05:34 +00:00
CGObjCRuntime.h Clean up CGObjCMac's APIs for deriving class references. NFC. 2016-11-30 23:54:50 +00:00
CGOpenCLRuntime.cpp [OpenCL] Fix layering violation by getOpenCLTypeAddrSpace 2017-12-06 10:11:28 +00:00
CGOpenCLRuntime.h [OpenCL] Emit enqueued block as kernel 2017-10-14 12:23:50 +00:00
CGOpenMPRuntime.cpp [OPENMP] Add debug info for generated functions. 2018-01-04 19:45:16 +00:00
CGOpenMPRuntime.h [OPENMP] Add debug info for generated functions. 2018-01-04 19:45:16 +00:00
CGOpenMPRuntimeNVPTX.cpp [OPENMP] Fix casting in NVPTX support library. 2018-01-04 20:18:55 +00:00
CGOpenMPRuntimeNVPTX.h [OPENMP] Add debug info for generated functions. 2018-01-04 19:45:16 +00:00
CGRecordLayout.h Make CodeGen headers self-contained. 2016-02-02 16:05:18 +00:00
CGRecordLayoutBuilder.cpp [Bitfield] Add an option to access bitfield in a fine-grained manner. 2017-10-16 16:50:27 +00:00
CGStmt.cpp [OPENMP] Support for -fopenmp-simd option with compilation of simd loops 2017-12-29 18:07:07 +00:00
CGStmtOpenMP.cpp [OpenMP] Initial implementation of code generation for pragma 'target teams distribute parallel for' on host 2018-01-03 21:12:44 +00:00
CGVTT.cpp Reland "Fix vtable not receiving hidden visibility when using push(visibility)" 2017-11-29 00:54:20 +00:00
CGVTables.cpp Reland "Fix vtable not receiving hidden visibility when using push(visibility)" 2017-11-29 00:54:20 +00:00
CGVTables.h CodeGen: New vtable group representation: struct of vtable arrays. 2016-12-13 20:40:39 +00:00
CGValue.h [CodeGen] Propagate may-alias'ness of lvalues with TBAA info 2017-10-31 11:05:34 +00:00
CMakeLists.txt Promote ConstantInitBuilder to be a public CodeGen API; it's 2017-03-02 20:04:19 +00:00
CodeGenABITypes.cpp Include getting generated struct offsets in CodegenABITypes 2017-10-10 23:54:21 +00:00
CodeGenAction.cpp Handle/assert on DK_Remark 2017-10-12 23:56:54 +00:00
CodeGenFunction.cpp No -fsanitize=function warning when calling noexcept function through non-noexcept pointer in C++17 2018-01-05 07:57:12 +00:00
CodeGenFunction.h [OpenMP] Initial implementation of code generation for pragma 'target teams distribute parallel for' on host 2018-01-03 21:12:44 +00:00
CodeGenModule.cpp [OPENMP] Support for -fopenmp-simd option with compilation of simd loops 2017-12-29 18:07:07 +00:00
CodeGenModule.h [Coverage] Always emit unused coverage mappings in the same order. 2017-12-13 00:14:17 +00:00
CodeGenPGO.cpp Mark all library options as hidden. 2017-12-01 00:53:10 +00:00
CodeGenPGO.h Remove a dead field. NFC. 2017-04-24 20:54:36 +00:00
CodeGenTBAA.cpp [CodeGen] Represent array members in new-format TBAA type descriptors 2017-12-22 09:57:24 +00:00
CodeGenTBAA.h Revert "[CodeGen] Add initial support for union members in TBAA" 2017-12-03 03:10:13 +00:00
CodeGenTypeCache.h [AARch64] Add ARMv8.2-A FP16 vector intrinsics 2017-12-21 19:20:01 +00:00
CodeGenTypes.cpp [CodeGen][X86] Fix handling of __fp16 vectors. 2017-12-09 00:02:37 +00:00
CodeGenTypes.h [OpenCL] Emit enqueued block as kernel 2017-10-14 12:23:50 +00:00
ConstantEmitter.h Convert clang::LangAS to a strongly typed enum 2017-10-15 18:48:14 +00:00
ConstantInitBuilder.cpp Further fixes and improvements to the ConstantInitBuilder API. 2017-03-06 19:04:16 +00:00
CoverageMappingGen.cpp [Coverage] Emit gap areas in braces-optional statements (PR35387) 2017-11-29 22:25:14 +00:00
CoverageMappingGen.h [Lexer] Report more precise skipped regions (PR34166) 2017-09-11 20:47:42 +00:00
EHScopeStack.h Spelling mistakes in comments. NFCI. (PR27635) 2017-03-30 14:13:19 +00:00
ItaniumCXXABI.cpp No -fsanitize=function warning when calling noexcept function through non-noexcept pointer in C++17 2018-01-05 07:57:12 +00:00
MacroPPCallbacks.cpp [NFC] Refactor the Preprocessor function that handles Macro definitions and rename Arguments to Parameters in Macro Definitions. 2017-07-17 17:18:43 +00:00
MacroPPCallbacks.h Fix API breaks 2017-04-26 20:58:21 +00:00
MicrosoftCXXABI.cpp IRGen: When performing CFI checks, load vtable pointer from vbase when necessary. 2017-12-13 21:53:04 +00:00
ModuleBuilder.cpp D34444: Teach codegen to work in incremental processing mode. 2017-08-27 10:58:03 +00:00
ObjectFilePCHContainerOperations.cpp -gmodules: Emit debug info for implicit module imports via #include. 2018-01-03 19:10:21 +00:00
README.txt
SanitizerMetadata.cpp Hardware-assisted AddressSanitizer (clang part). 2017-12-09 01:32:07 +00:00
SanitizerMetadata.h
SwiftCallingConv.cpp SwiftCC: Perform physical layout when computing coercion types 2017-06-21 21:43:40 +00:00
TargetInfo.cpp SystemZ Swift TargetInfo: swifterror support in the backend is broken 2017-11-07 16:40:51 +00:00
TargetInfo.h Convert clang::LangAS to a strongly typed enum 2017-10-15 18:48:14 +00:00
VarBypassDetector.cpp [CodeGen] Don't emit lifetime intrinsics for some local variables 2016-10-26 05:42:30 +00:00
VarBypassDetector.h [CodeGen] Don't emit lifetime intrinsics for some local variables 2016-10-26 05:42:30 +00:00

README.txt

IRgen optimization opportunities.

//===---------------------------------------------------------------------===//

The common pattern of
--
short x; // or char, etc
(x == 10)
--
generates an zext/sext of x which can easily be avoided.

//===---------------------------------------------------------------------===//

Bitfields accesses can be shifted to simplify masking and sign
extension. For example, if the bitfield width is 8 and it is
appropriately aligned then is is a lot shorter to just load the char
directly.

//===---------------------------------------------------------------------===//

It may be worth avoiding creation of alloca's for formal arguments
for the common situation where the argument is never written to or has
its address taken. The idea would be to begin generating code by using
the argument directly and if its address is taken or it is stored to
then generate the alloca and patch up the existing code.

In theory, the same optimization could be a win for block local
variables as long as the declaration dominates all statements in the
block.

NOTE: The main case we care about this for is for -O0 -g compile time
performance, and in that scenario we will need to emit the alloca
anyway currently to emit proper debug info. So this is blocked by
being able to emit debug information which refers to an LLVM
temporary, not an alloca.

//===---------------------------------------------------------------------===//

We should try and avoid generating basic blocks which only contain
jumps. At -O0, this penalizes us all the way from IRgen (malloc &
instruction overhead), all the way down through code generation and
assembly time.

On 176.gcc:expr.ll, it looks like over 12% of basic blocks are just
direct branches!

//===---------------------------------------------------------------------===//