llvm/lib/Support
Duncan P. N. Exon Smith 3e97be26b9 ADT: Share code for embedded sentinel traits, NFC
Share code for the (mostly problematic) embedded sentinel traits.
- Move the LLVM_NO_SANITIZE("object-size") attribute to
  ilist_half_embedded_sentinel_traits and ilist_embedded_sentinel_traits
  (previously it spread throughout the code duplication).
- Add an ilist_full_embedded_sentinel_traits which has no UB (but has
  the downside of storing the complete node).
- Replace all the custom sentinel traits in LLVM with a declaration of
  ilist_sentinel_traits that inherits from one of the embedded sentinel
  traits classes.

There are still custom sentinel traits in other LLVM subprojects.  I'll
remove those in a follow-up.

Nothing at all should be changing here, this is just rearranging code.
Note that the final goal here is to remove the sentinel traits
altogether, settling on the memory layout of
ilist_half_embedded_sentinel_traits without the UB.  This intermediate
step moves the logic into ilist.h.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@278513 91177308-0d34-0410-b5e6-96231b3b80d8
2016-08-12 15:00:55 +00:00
..
Unix Use the range variant of find/find_if instead of unpacking begin/end 2016-08-12 03:55:06 +00:00
Windows Use the range variant of find/find_if instead of unpacking begin/end 2016-08-12 03:55:06 +00:00
Allocator.cpp
APFloat.cpp
APInt.cpp Fix UB in APInt::ashr 2016-08-10 19:50:14 +00:00
APSInt.cpp
ARMBuildAttrs.cpp
ARMWinEH.cpp
Atomic.cpp Remove all of the legacy home-grown atomic operations LLVM provided 2016-06-02 17:11:11 +00:00
BlockFrequency.cpp
BranchProbability.cpp
CachePruning.cpp CachePruning: correct comment about file order. NFC 2016-06-27 08:46:23 +00:00
circular_raw_ostream.cpp
CMakeLists.txt
COM.cpp
CommandLine.cpp Use the range variant of find instead of unpacking begin/end 2016-08-11 22:21:41 +00:00
Compression.cpp
ConvertUTF.c
ConvertUTFWrapper.cpp
COPYRIGHT.regex
CrashRecoveryContext.cpp
DAGDeltaAlgorithm.cpp
DataExtractor.cpp
DataStream.cpp
Debug.cpp
DeltaAlgorithm.cpp
Dwarf.cpp Synchronize LLVM and clang's ObjCDeclSpec::ObjCPropertyAttributeKind. 2016-07-14 00:41:18 +00:00
DynamicLibrary.cpp
Errno.cpp
Error.cpp [Object] Re-apply r275316 now that I have the corresponding LLD patch ready. 2016-07-14 02:24:01 +00:00
ErrorHandling.cpp
FileOutputBuffer.cpp
FileUtilities.cpp
FoldingSet.cpp Adding reserve and capacity methods to FoldingSet 2016-06-03 13:54:48 +00:00
FormattedStream.cpp
GraphWriter.cpp
Hashing.cpp
Host.cpp Properly ifdef the use of cpuid. 2016-07-20 18:54:26 +00:00
IntEqClasses.cpp
IntervalMap.cpp
IntrusiveRefCntPtr.cpp
JamCRC.cpp
LEB128.cpp
LineIterator.cpp
LLVMBuild.txt
Locale.cpp
LockFileManager.cpp [LockFileManager] Improve error output by using better error messages 2016-06-04 00:34:00 +00:00
ManagedStatic.cpp [ManagedStatic] Reimplement double-checked locking with std::atomic. 2016-06-29 15:04:07 +00:00
MathExtras.cpp
MD5.cpp
Memory.cpp
MemoryBuffer.cpp
MemoryObject.cpp
Mutex.cpp
Options.cpp
Path.cpp Add support for Darwin’s 64-bit universal files with 64-bit offsets and sizes for the objects. 2016-06-20 22:16:18 +00:00
PluginLoader.cpp
PrettyStackTrace.cpp Use C++ casts to avoid a warning 2016-05-27 23:04:28 +00:00
Process.cpp
Program.cpp
RandomNumberGenerator.cpp
raw_os_ostream.cpp
raw_ostream.cpp
README.txt.system
regcclass.h
regcname.h
regcomp.c
regengine.inc
regerror.c
regex2.h
regex_impl.h
Regex.cpp
regexec.c
regfree.c
regstrlcpy.c
regutils.h
RWMutex.cpp
ScaledNumber.cpp
ScopedPrinter.cpp
SearchForAddressOfSpecialSymbol.cpp
SHA1.cpp
Signals.cpp Search for llvm-symbolizer binary in the same directory as argv[0], before 2016-06-09 00:53:21 +00:00
SmallPtrSet.cpp
SmallVector.cpp
SourceMgr.cpp Use the range variant of find_if instead of unpacking begin/end 2016-08-12 00:18:03 +00:00
SpecialCaseList.cpp Avoid some copies by using const references. 2016-05-27 12:30:51 +00:00
Statistic.cpp Statistic: Add machine parseable json output 2016-06-15 20:19:16 +00:00
StreamingMemoryObject.cpp
StringExtras.cpp
StringMap.cpp
StringPool.cpp
StringRef.cpp
StringSaver.cpp
SystemUtils.cpp
TargetParser.cpp Add unittests to {ARM | AArch64}TargetParser. 2016-07-28 06:11:18 +00:00
TargetRegistry.cpp Use the range variant of find_if instead of unpacking begin/end 2016-08-12 00:18:03 +00:00
Threading.cpp [LPM] Reinstate r271781 which reinstated r271652 to replace the 2016-06-04 19:57:55 +00:00
ThreadLocal.cpp
ThreadPool.cpp Removing whitespace from test commit rL273447 2016-06-22 18:01:11 +00:00
Timer.cpp Test commit. Removes some spaces. No functionality changed. 2016-06-03 19:20:37 +00:00
TimeValue.cpp
ToolOutputFile.cpp
Triple.cpp [mips] Recognise the triple used by Debian stretch for mips64el. 2016-07-19 10:22:19 +00:00
Twine.cpp
Unicode.cpp
Valgrind.cpp
Watchdog.cpp
YAMLParser.cpp ADT: Share code for embedded sentinel traits, NFC 2016-08-12 15:00:55 +00:00
YAMLTraits.cpp [YAML] Fix YAML tags appearing before the start of sequence elements 2016-06-28 21:10:26 +00:00

Design Of lib/System
====================

The software in this directory is designed to completely shield LLVM from any
and all operating system specific functionality. It is not intended to be a
complete operating system wrapper (such as ACE), but only to provide the
functionality necessary to support LLVM.

The software located here, of necessity, has very specific and stringent design
rules. Violation of these rules means that cracks in the shield could form and
the primary goal of the library is defeated. By consistently using this library,
LLVM becomes more easily ported to new platforms since the only thing requiring
porting is this library.

Complete documentation for the library can be found in the file:
  llvm/docs/SystemLibrary.html
or at this URL:
  http://llvm.org/docs/SystemLibrary.html

While we recommend that you read the more detailed documentation, for the
impatient, here's a high level summary of the library's requirements.

 1. No system header files are to be exposed through the interface.
 2. Std C++ and Std C header files are okay to be exposed through the interface.
 3. No exposed system-specific functions.
 4. No exposed system-specific data.
 5. Data in lib/System classes must use only simple C++ intrinsic types.
 6. Errors are handled by returning "true" and setting an optional std::string
 7. Library must not throw any exceptions, period.
 8. Interface functions must not have throw() specifications.
 9. No duplicate function impementations are permitted within an operating
    system class.

To accomplish these requirements, the library has numerous design criteria that
must be satisfied. Here's a high level summary of the library's design criteria:

 1. No unused functionality (only what LLVM needs)
 2. High-Level Interfaces
 3. Use Opaque Classes
 4. Common Implementations
 5. Multiple Implementations
 6. Minimize Memory Allocation
 7. No Virtual Methods