[llvm] r233310 - [ADT][CMake][AutoConf] Fail-fast iterators for DenseMap
Sanjoy Das
sanjoy at playingwithpointers.com
Mon Mar 30 09:32:18 PDT 2015
Ideally, clang should not need to worry about this option at all -- it
is handled entirely within LLVM and is used to generate a "#define
LLVM_ENABLE_ABI_BREAKING_CHECKS" (or not) in
llvm/Config/llvm-config.h, and that header is included by all headers
from LLVM that need it. Does building clang with an existing llvm
re-generate llvm/Config/llvm-config.h?
In any case, I think the safest bet is to pretend
LLVM_ABI_BREAKING_CHECKS="" is LLVM_ABI_BREAKING_CHECKS="FORCE_OFF".
If you have an easy way to test this, can you please try this patch:
diff --git a/cmake/modules/HandleLLVMOptions.cmake
b/cmake/modules/HandleLLVMOptions.cmake
index 67f86a6..898af87 100644
--- a/cmake/modules/HandleLLVMOptions.cmake
+++ b/cmake/modules/HandleLLVMOptions.cmake
@@ -88,6 +88,10 @@ elseif( uppercase_LLVM_ABI_BREAKING_CHECKS STREQUAL
"FORCE_ON" )
set( LLVM_ENABLE_ABI_BREAKING_CHECKS 1 )
elseif( uppercase_LLVM_ABI_BREAKING_CHECKS STREQUAL "FORCE_OFF" )
# We don't need to do anything special to turn off ABI breaking checks.
+elseif ( uppercase_LLVM_ABI_BREAKING_CHECKS STREQUAL "" )
+ # We're being run with a cached value of LLVM_ABI_BREAKING_CHECKS that is an
+ # empty string. This means we're building against an LLVM that did not have
+ # this enabled when configured, so treat this like "FORCE_OFF"
else()
message(FATAL_ERROR "Unknown value for LLVM_ABI_BREAKING_CHECKS:
"${LLVM_ABI_BREAKING_CHECKS}"!")
endif()
If not, please let me know, I'll try reproducing this myself.
-- Sanjoy
On Mon, Mar 30, 2015 at 2:24 AM, Daniel Sanders
<Daniel.Sanders at imgtec.com> wrote:
> Hi,
>
> It seems that this change has broken clang builds where clang is built for an already-compiled llvm. See http://buildbot.llvm.linuxfoundation.org/builders/malta/builds/87/steps/shell_3/logs/stdio for the full log but the relevant part is:
> -- Found LLVM_CONFIG as /home/das/llvm-linux/llvmlinux/toolchain/clang/head/install/bin/llvm-config
> CMake Error at /home/das/llvm-linux/llvmlinux/toolchain/clang/head/install/share/llvm/cmake/HandleLLVMOptions.cmake:92 (message):
> Unknown value for LLVM_ABI_BREAKING_CHECKS: ""!
> Call Stack (most recent call first):
> CMakeLists.txt:102 (include)
>
> Should clang be setting this cmake variable from llvm-config or should it be setting it itself?
>
>> -----Original Message-----
>> From: llvm-commits-bounces at cs.uiuc.edu [mailto:llvm-commits-
>> bounces at cs.uiuc.edu] On Behalf Of Sanjoy Das
>> Sent: 26 March 2015 19:25
>> To: llvm-commits at cs.uiuc.edu
>> Subject: [llvm] r233310 - [ADT][CMake][AutoConf] Fail-fast iterators for
>> DenseMap
>>
>> Author: sanjoy
>> Date: Thu Mar 26 14:25:01 2015
>> New Revision: 233310
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=233310&view=rev
>> Log:
>> [ADT][CMake][AutoConf] Fail-fast iterators for DenseMap
>>
>> Summary:
>> This patch is an attempt at making `DenseMapIterator`s "fail-fast".
>> Fail-fast iterators that have been invalidated due to insertion into
>> the host `DenseMap` deterministically trip an assert (in debug mode)
>> on access, instead of non-deterministically hitting memory corruption
>> issues.
>>
>> Enabling fail-fast iterators breaks the LLVM C++ ABI, so they are
>> predicated on `LLVM_ENABLE_ABI_BREAKING_CHECKS`.
>> `LLVM_ENABLE_ABI_BREAKING_CHECKS` by default flips with
>> `LLVM_ENABLE_ASSERTS`, but can be clamped to ON or OFF using the CMake
>> /
>> autoconf build system.
>>
>> Reviewers: chandlerc, dexonsmith, rnk, zturner
>>
>> Subscribers: llvm-commits
>>
>> Differential Revision: http://reviews.llvm.org/D8351
>>
>> Added:
>> llvm/trunk/include/llvm/ADT/EpochTracker.h
>> Modified:
>> llvm/trunk/CMakeLists.txt
>> llvm/trunk/autoconf/configure.ac
>> llvm/trunk/cmake/modules/HandleLLVMOptions.cmake
>> llvm/trunk/configure
>> llvm/trunk/docs/CMake.rst
>> llvm/trunk/docs/ProgrammersManual.rst
>> llvm/trunk/include/llvm/ADT/DenseMap.h
>> llvm/trunk/include/llvm/Config/config.h.in
>> llvm/trunk/include/llvm/Config/llvm-config.h.cmake
>> llvm/trunk/include/llvm/Config/llvm-config.h.in
>>
>> Modified: llvm/trunk/CMakeLists.txt
>> URL: http://llvm.org/viewvc/llvm-
>> project/llvm/trunk/CMakeLists.txt?rev=233310&r1=233309&r2=233310&view
>> =diff
>> ==========================================================
>> ====================
>> --- llvm/trunk/CMakeLists.txt (original)
>> +++ llvm/trunk/CMakeLists.txt Thu Mar 26 14:25:01 2015
>> @@ -252,6 +252,9 @@ else()
>> option(LLVM_ENABLE_ASSERTIONS "Enable assertions" ON)
>> endif()
>>
>> +set(LLVM_ABI_BREAKING_CHECKS "WITH_ASSERTS" CACHE STRING
>> + "Enable abi-breaking checks. Can be WITH_ASSERTS, FORCE_ON or
>> FORCE_OFF.")
>> +
>> option(LLVM_FORCE_USE_OLD_HOST_TOOLCHAIN
>> "Set to ON to force using an old, unsupported host toolchain." OFF)
>>
>>
>> Modified: llvm/trunk/autoconf/configure.ac
>> URL: http://llvm.org/viewvc/llvm-
>> project/llvm/trunk/autoconf/configure.ac?rev=233310&r1=233309&r2=23331
>> 0&view=diff
>> ==========================================================
>> ====================
>> --- llvm/trunk/autoconf/configure.ac (original)
>> +++ llvm/trunk/autoconf/configure.ac Thu Mar 26 14:25:01 2015
>> @@ -701,8 +701,10 @@ AC_ARG_ENABLE(assertions,AS_HELP_STRING(
>> --enable-assertions,[Compile with assertion checks enabled (default is
>> YES)]),, enableval="yes")
>> if test ${enableval} = "yes" ; then
>> AC_SUBST(DISABLE_ASSERTIONS,[[]])
>> + assertions_enabled="yes"
>> else
>> AC_SUBST(DISABLE_ASSERTIONS,[[DISABLE_ASSERTIONS=1]])
>> + assertions_enabled="no"
>> fi
>>
>> dnl --enable-werror : check whether we want Werror on by default
>> @@ -726,6 +728,20 @@ else
>> AC_SUBST(EXPENSIVE_CHECKS,[[no]])
>> fi
>>
>> +dnl --enable-abi-breaking-checks : decide whether we should compile in
>> asserts and
>> +dnl checks that make the build ABI incompatible with an llvm built without
>> these
>> +dnl checks enabled.
>> +AC_ARG_ENABLE(abi-breaking-checks,AS_HELP_STRING(
>> + --enable-abi-breaking-checks,[Compile with abi-breaking asserts support
>> (default is with-asserts)]),, enableval="with-asserts")
>> +case "$enableval" in
>> + with-asserts) if test ${assertions_enabled} = "yes" ; then
>> + AC_DEFINE([LLVM_ENABLE_ABI_BREAKING_CHECKS],[1],[Define
>> to enable checks that alter the LLVM C++ ABI])
>> + fi ;;
>> + yes) AC_DEFINE([LLVM_ENABLE_ABI_BREAKING_CHECKS],[1],[Define to
>> enable checks that alter the LLVM C++ ABI]) ;;
>> + no) ;;
>> + *) AC_MSG_ERROR([Invalid setting for --enable-abi-breaking-checks. Use
>> "with-asserts", "yes" or "no"])
>> +esac
>> +
>> dnl --enable-debug-runtime : should runtime libraries have debug symbols?
>> AC_ARG_ENABLE(debug-runtime,
>> AS_HELP_STRING(--enable-debug-runtime,[Build runtime libs with debug
>> symbols (default is NO)]),,enableval=no)
>>
>> Modified: llvm/trunk/cmake/modules/HandleLLVMOptions.cmake
>> URL: http://llvm.org/viewvc/llvm-
>> project/llvm/trunk/cmake/modules/HandleLLVMOptions.cmake?rev=23331
>> 0&r1=233309&r2=233310&view=diff
>> ==========================================================
>> ====================
>> --- llvm/trunk/cmake/modules/HandleLLVMOptions.cmake (original)
>> +++ llvm/trunk/cmake/modules/HandleLLVMOptions.cmake Thu Mar 26
>> 14:25:01 2015
>> @@ -78,6 +78,20 @@ if( LLVM_ENABLE_ASSERTIONS )
>> endif()
>> endif()
>>
>> +string(TOUPPER "${LLVM_ABI_BREAKING_CHECKS}"
>> uppercase_LLVM_ABI_BREAKING_CHECKS)
>> +
>> +if( uppercase_LLVM_ABI_BREAKING_CHECKS STREQUAL "WITH_ASSERTS" )
>> + if( LLVM_ENABLE_ASSERTIONS )
>> + set( LLVM_ENABLE_ABI_BREAKING_CHECKS 1 )
>> + endif()
>> +elseif( uppercase_LLVM_ABI_BREAKING_CHECKS STREQUAL "FORCE_ON" )
>> + set( LLVM_ENABLE_ABI_BREAKING_CHECKS 1 )
>> +elseif( uppercase_LLVM_ABI_BREAKING_CHECKS STREQUAL "FORCE_OFF"
>> )
>> + # We don't need to do anything special to turn off ABI breaking checks.
>> +else()
>> + message(FATAL_ERROR "Unknown value for
>> LLVM_ABI_BREAKING_CHECKS: \"${LLVM_ABI_BREAKING_CHECKS}\"!")
>> +endif()
>> +
>> if(WIN32)
>> set(LLVM_HAVE_LINK_VERSION_SCRIPT 0)
>> if(CYGWIN)
>>
>> Modified: llvm/trunk/configure
>> URL: http://llvm.org/viewvc/llvm-
>> project/llvm/trunk/configure?rev=233310&r1=233309&r2=233310&view=diff
>> ==========================================================
>> ====================
>> --- llvm/trunk/configure (original)
>> +++ llvm/trunk/configure Thu Mar 26 14:25:01 2015
>> @@ -1426,6 +1426,9 @@ Optional Features:
>> --enable-expensive-checks
>> Compile with expensive debug checks enabled (default
>> is NO)
>> + --enable-abi-breaking-checks
>> + Compile with abi-breaking asserts support (default
>> + is with-asserts)
>> --enable-debug-runtime Build runtime libs with debug symbols (default is
>> NO)
>> --enable-debug-symbols Build compiler with debug symbols (default is NO
>> if
>> @@ -4980,9 +4983,11 @@ fi
>> if test ${enableval} = "yes" ; then
>> DISABLE_ASSERTIONS=
>>
>> + assertions_enabled="yes"
>> else
>> DISABLE_ASSERTIONS=DISABLE_ASSERTIONS=1
>>
>> + assertions_enabled="no"
>> fi
>>
>> # Check whether --enable-werror was given.
>> @@ -5023,6 +5028,32 @@ else
>>
>> fi
>>
>> +# Check whether --enable-abi-breaking-checks was given.
>> +if test "${enable_abi_breaking_checks+set}" = set; then
>> + enableval=$enable_abi_breaking_checks;
>> +else
>> + enableval="with-asserts"
>> +fi
>> +
>> +case "$enableval" in
>> + with-asserts) if test ${assertions_enabled} = "yes" ; then
>> +
>> +cat >>confdefs.h <<\_ACEOF
>> +#define LLVM_ENABLE_ABI_BREAKING_CHECKS 1
>> +_ACEOF
>> +
>> + fi ;;
>> + yes)
>> +cat >>confdefs.h <<\_ACEOF
>> +#define LLVM_ENABLE_ABI_BREAKING_CHECKS 1
>> +_ACEOF
>> + ;;
>> + no) ;;
>> + *) { { echo "$as_me:$LINENO: error: Invalid setting for --enable-abi-
>> breaking-checks. Use \"with-asserts\", \"yes\" or \"no\"" >&5
>> +echo "$as_me: error: Invalid setting for --enable-abi-breaking-checks. Use
>> \"with-asserts\", \"yes\" or \"no\"" >&2;}
>> + { (exit 1); exit 1; }; }
>> +esac
>> +
>> # Check whether --enable-debug-runtime was given.
>> if test "${enable_debug_runtime+set}" = set; then
>> enableval=$enable_debug_runtime;
>>
>> Modified: llvm/trunk/docs/CMake.rst
>> URL: http://llvm.org/viewvc/llvm-
>> project/llvm/trunk/docs/CMake.rst?rev=233310&r1=233309&r2=233310&vie
>> w=diff
>> ==========================================================
>> ====================
>> --- llvm/trunk/docs/CMake.rst (original)
>> +++ llvm/trunk/docs/CMake.rst Thu Mar 26 14:25:01 2015
>> @@ -270,6 +270,15 @@ LLVM-specific variables
>> **LLVM_ENABLE_WERROR**:BOOL
>> Stop and fail build, if a compiler warning is triggered. Defaults to OFF.
>>
>> +**LLVM_ABI_BREAKING_CHECKS**:STRING
>> + Used to decide if LLVM should be built with ABI breaking checks or
>> + not. Allowed values are `WITH_ASSERTS` (default), `FORCE_ON` and
>> + `FORCE_OFF`. `WITH_ASSERTS` turns on ABI breaking checks in an
>> + assertion enabled build. `FORCE_ON` (`FORCE_OFF`) turns them on
>> + (off) irrespective of whether normal (`NDEBUG` based) assertions are
>> + enabled or not. A version of LLVM built with ABI breaking checks
>> + is not ABI compatible with a version built without it.
>> +
>> **LLVM_BUILD_32_BITS**:BOOL
>> Build 32-bits executables and libraries on 64-bits systems. This option is
>> available only on some 64-bits unix systems. Defaults to OFF.
>>
>> Modified: llvm/trunk/docs/ProgrammersManual.rst
>> URL: http://llvm.org/viewvc/llvm-
>> project/llvm/trunk/docs/ProgrammersManual.rst?rev=233310&r1=233309&r
>> 2=233310&view=diff
>> ==========================================================
>> ====================
>> --- llvm/trunk/docs/ProgrammersManual.rst (original)
>> +++ llvm/trunk/docs/ProgrammersManual.rst Thu Mar 26 14:25:01 2015
>> @@ -2553,6 +2553,22 @@ section on :ref:`isa and dyn_cast <isa>`
>> <HowToSetUpLLVMStyleRTTI>` which describes how you can implement this
>> pattern for use with the LLVM helpers.
>>
>> +.. _abi_breaking_checks:
>> +
>> +ABI Breaking Checks
>> +-------------------
>> +
>> +Checks and asserts that alter the LLVM C++ ABI are predicated on the
>> +preprocessor symbol `LLVM_ENABLE_ABI_BREAKING_CHECKS` -- LLVM
>> +libraries built with `LLVM_ENABLE_ABI_BREAKING_CHECKS` are not ABI
>> +compatible LLVM libraries built without it defined. By default,
>> +turning on assertions also turns on
>> `LLVM_ENABLE_ABI_BREAKING_CHECKS`
>> +so a default +Asserts build is not ABI compatible with a
>> +default -Asserts build. Clients that want ABI compatibility
>> +between +Asserts and -Asserts builds should use the CMake or autoconf
>> +build systems to set `LLVM_ENABLE_ABI_BREAKING_CHECKS`
>> independently
>> +of `LLVM_ENABLE_ASSERTIONS`.
>> +
>> .. _coreclasses:
>>
>> The Core LLVM Class Hierarchy Reference
>>
>> Modified: llvm/trunk/include/llvm/ADT/DenseMap.h
>> URL: http://llvm.org/viewvc/llvm-
>> project/llvm/trunk/include/llvm/ADT/DenseMap.h?rev=233310&r1=233309&
>> r2=233310&view=diff
>> ==========================================================
>> ====================
>> --- llvm/trunk/include/llvm/ADT/DenseMap.h (original)
>> +++ llvm/trunk/include/llvm/ADT/DenseMap.h Thu Mar 26 14:25:01 2015
>> @@ -15,6 +15,7 @@
>> #define LLVM_ADT_DENSEMAP_H
>>
>> #include "llvm/ADT/DenseMapInfo.h"
>> +#include "llvm/ADT/EpochTracker.h"
>> #include "llvm/Support/AlignOf.h"
>> #include "llvm/Support/Compiler.h"
>> #include "llvm/Support/MathExtras.h"
>> @@ -50,7 +51,7 @@ class DenseMapIterator;
>>
>> template <typename DerivedT, typename KeyT, typename ValueT,
>> typename KeyInfoT,
>> typename BucketT>
>> -class DenseMapBase {
>> +class DenseMapBase : public DebugEpochBase {
>> public:
>> typedef unsigned size_type;
>> typedef KeyT key_type;
>> @@ -62,16 +63,17 @@ public:
>> const_iterator;
>> inline iterator begin() {
>> // When the map is empty, avoid the overhead of
>> AdvancePastEmptyBuckets().
>> - return empty() ? end() : iterator(getBuckets(), getBucketsEnd());
>> + return empty() ? end() : iterator(getBuckets(), getBucketsEnd(), *this);
>> }
>> inline iterator end() {
>> - return iterator(getBucketsEnd(), getBucketsEnd(), true);
>> + return iterator(getBucketsEnd(), getBucketsEnd(), *this, true);
>> }
>> inline const_iterator begin() const {
>> - return empty() ? end() : const_iterator(getBuckets(), getBucketsEnd());
>> + return empty() ? end()
>> + : const_iterator(getBuckets(), getBucketsEnd(), *this);
>> }
>> inline const_iterator end() const {
>> - return const_iterator(getBucketsEnd(), getBucketsEnd(), true);
>> + return const_iterator(getBucketsEnd(), getBucketsEnd(), *this, true);
>> }
>>
>> bool LLVM_ATTRIBUTE_UNUSED_RESULT empty() const {
>> @@ -81,11 +83,13 @@ public:
>>
>> /// Grow the densemap so that it has at least Size buckets. Does not shrink
>> void resize(size_type Size) {
>> + incrementEpoch();
>> if (Size > getNumBuckets())
>> grow(Size);
>> }
>>
>> void clear() {
>> + incrementEpoch();
>> if (getNumEntries() == 0 && getNumTombstones() == 0) return;
>>
>> // If the capacity of the array is huge, and the # elements used is small,
>> @@ -118,13 +122,13 @@ public:
>> iterator find(const KeyT &Val) {
>> BucketT *TheBucket;
>> if (LookupBucketFor(Val, TheBucket))
>> - return iterator(TheBucket, getBucketsEnd(), true);
>> + return iterator(TheBucket, getBucketsEnd(), *this, true);
>> return end();
>> }
>> const_iterator find(const KeyT &Val) const {
>> const BucketT *TheBucket;
>> if (LookupBucketFor(Val, TheBucket))
>> - return const_iterator(TheBucket, getBucketsEnd(), true);
>> + return const_iterator(TheBucket, getBucketsEnd(), *this, true);
>> return end();
>> }
>>
>> @@ -137,14 +141,14 @@ public:
>> iterator find_as(const LookupKeyT &Val) {
>> BucketT *TheBucket;
>> if (LookupBucketFor(Val, TheBucket))
>> - return iterator(TheBucket, getBucketsEnd(), true);
>> + return iterator(TheBucket, getBucketsEnd(), *this, true);
>> return end();
>> }
>> template<class LookupKeyT>
>> const_iterator find_as(const LookupKeyT &Val) const {
>> const BucketT *TheBucket;
>> if (LookupBucketFor(Val, TheBucket))
>> - return const_iterator(TheBucket, getBucketsEnd(), true);
>> + return const_iterator(TheBucket, getBucketsEnd(), *this, true);
>> return end();
>> }
>>
>> @@ -163,12 +167,13 @@ public:
>> std::pair<iterator, bool> insert(const std::pair<KeyT, ValueT> &KV) {
>> BucketT *TheBucket;
>> if (LookupBucketFor(KV.first, TheBucket))
>> - return std::make_pair(iterator(TheBucket, getBucketsEnd(), true),
>> + return std::make_pair(iterator(TheBucket, getBucketsEnd(), *this, true),
>> false); // Already in map.
>>
>> // Otherwise, insert the new element.
>> TheBucket = InsertIntoBucket(KV.first, KV.second, TheBucket);
>> - return std::make_pair(iterator(TheBucket, getBucketsEnd(), true), true);
>> + return std::make_pair(iterator(TheBucket, getBucketsEnd(), *this, true),
>> + true);
>> }
>>
>> // Inserts key,value pair into the map if the key isn't already in the map.
>> @@ -177,14 +182,15 @@ public:
>> std::pair<iterator, bool> insert(std::pair<KeyT, ValueT> &&KV) {
>> BucketT *TheBucket;
>> if (LookupBucketFor(KV.first, TheBucket))
>> - return std::make_pair(iterator(TheBucket, getBucketsEnd(), true),
>> + return std::make_pair(iterator(TheBucket, getBucketsEnd(), *this, true),
>> false); // Already in map.
>> -
>> +
>> // Otherwise, insert the new element.
>> TheBucket = InsertIntoBucket(std::move(KV.first),
>> std::move(KV.second),
>> TheBucket);
>> - return std::make_pair(iterator(TheBucket, getBucketsEnd(), true), true);
>> + return std::make_pair(iterator(TheBucket, getBucketsEnd(), *this, true),
>> + true);
>> }
>>
>> /// insert - Range insertion of pairs.
>> @@ -431,6 +437,8 @@ private:
>> }
>>
>> BucketT *InsertIntoBucketImpl(const KeyT &Key, BucketT *TheBucket) {
>> + incrementEpoch();
>> +
>> // If the load of the hash table is more than 3/4, or if fewer than 1/8 of
>> // the buckets are empty (meaning that many are filled with tombstones),
>> // grow the table.
>> @@ -987,9 +995,10 @@ private:
>>
>> template <typename KeyT, typename ValueT, typename KeyInfoT,
>> typename Bucket,
>> bool IsConst>
>> -class DenseMapIterator {
>> +class DenseMapIterator : DebugEpochBase::HandleBase {
>> typedef DenseMapIterator<KeyT, ValueT, KeyInfoT, Bucket, true>
>> ConstIterator;
>> friend class DenseMapIterator<KeyT, ValueT, KeyInfoT, Bucket, true>;
>> + friend class DenseMapIterator<KeyT, ValueT, KeyInfoT, Bucket, false>;
>>
>> public:
>> typedef ptrdiff_t difference_type;
>> @@ -1003,8 +1012,10 @@ private:
>> public:
>> DenseMapIterator() : Ptr(nullptr), End(nullptr) {}
>>
>> - DenseMapIterator(pointer Pos, pointer E, bool NoAdvance = false)
>> - : Ptr(Pos), End(E) {
>> + DenseMapIterator(pointer Pos, pointer E, const DebugEpochBase &Epoch,
>> + bool NoAdvance = false)
>> + : DebugEpochBase::HandleBase(&Epoch), Ptr(Pos), End(E) {
>> + assert(isHandleInSync() && "invalid construction!");
>> if (!NoAdvance) AdvancePastEmptyBuckets();
>> }
>>
>> @@ -1015,28 +1026,40 @@ public:
>> typename = typename std::enable_if<!IsConstSrc && IsConst>::type>
>> DenseMapIterator(
>> const DenseMapIterator<KeyT, ValueT, KeyInfoT, Bucket, IsConstSrc> &I)
>> - : Ptr(I.Ptr), End(I.End) {}
>> + : DebugEpochBase::HandleBase(I), Ptr(I.Ptr), End(I.End) {}
>>
>> reference operator*() const {
>> + assert(isHandleInSync() && "invalid iterator access!");
>> return *Ptr;
>> }
>> pointer operator->() const {
>> + assert(isHandleInSync() && "invalid iterator access!");
>> return Ptr;
>> }
>>
>> bool operator==(const ConstIterator &RHS) const {
>> - return Ptr == RHS.operator->();
>> + assert((!Ptr || isHandleInSync()) && "handle not in sync!");
>> + assert((!RHS.Ptr || RHS.isHandleInSync()) && "handle not in sync!");
>> + assert(getEpochAddress() == RHS.getEpochAddress() &&
>> + "comparing incomparable iterators!");
>> + return Ptr == RHS.Ptr;
>> }
>> bool operator!=(const ConstIterator &RHS) const {
>> - return Ptr != RHS.operator->();
>> + assert((!Ptr || isHandleInSync()) && "handle not in sync!");
>> + assert((!RHS.Ptr || RHS.isHandleInSync()) && "handle not in sync!");
>> + assert(getEpochAddress() == RHS.getEpochAddress() &&
>> + "comparing incomparable iterators!");
>> + return Ptr != RHS.Ptr;
>> }
>>
>> inline DenseMapIterator& operator++() { // Preincrement
>> + assert(isHandleInSync() && "invalid iterator access!");
>> ++Ptr;
>> AdvancePastEmptyBuckets();
>> return *this;
>> }
>> DenseMapIterator operator++(int) { // Postincrement
>> + assert(isHandleInSync() && "invalid iterator access!");
>> DenseMapIterator tmp = *this; ++*this; return tmp;
>> }
>>
>>
>> Added: llvm/trunk/include/llvm/ADT/EpochTracker.h
>> URL: http://llvm.org/viewvc/llvm-
>> project/llvm/trunk/include/llvm/ADT/EpochTracker.h?rev=233310&view=aut
>> o
>> ==========================================================
>> ====================
>> --- llvm/trunk/include/llvm/ADT/EpochTracker.h (added)
>> +++ llvm/trunk/include/llvm/ADT/EpochTracker.h Thu Mar 26 14:25:01 2015
>> @@ -0,0 +1,99 @@
>> +//===- llvm/ADT/EpochTracker.h - ADT epoch tracking --------------*- C++ -*-
>> ==//
>> +//
>> +// The LLVM Compiler Infrastructure
>> +//
>> +// This file is distributed under the University of Illinois Open Source
>> +// License. See LICENSE.TXT for details.
>> +//
>> +//===----------------------------------------------------------------------===//
>> +//
>> +// This file defines the DebugEpochBase and DebugEpochBase::HandleBase
>> classes.
>> +// These can be used to write iterators that are fail-fast when LLVM is built
>> +// with asserts enabled.
>> +//
>> +//===----------------------------------------------------------------------===//
>> +
>> +#ifndef LLVM_ADT_EPOCH_TRACKER_H
>> +#define LLVM_ADT_EPOCH_TRACKER_H
>> +
>> +#include "llvm/Config/llvm-config.h"
>> +
>> +#include <cstdint>
>> +
>> +namespace llvm {
>> +
>> +#ifndef LLVM_ENABLE_ABI_BREAKING_CHECKS
>> +
>> +class DebugEpochBase {
>> +public:
>> + void incrementEpoch() {}
>> +
>> + class HandleBase {
>> + public:
>> + HandleBase() {}
>> + explicit HandleBase(const DebugEpochBase *) {}
>> + bool isHandleInSync() const { return true; }
>> + const void *getEpochAddress() const { return nullptr; }
>> + };
>> +};
>> +
>> +#else
>> +
>> +/// \brief A base class for data structure classes wishing to make iterators
>> +/// ("handles") pointing into themselves fail-fast. When building without
>> +/// asserts, this class is empty and does nothing.
>> +///
>> +/// DebugEpochBase does not by itself track handles pointing into itself.
>> The
>> +/// expectation is that routines touching the handles will poll on
>> +/// isHandleInSync at appropriate points to assert that the handle they're
>> using
>> +/// is still valid.
>> +///
>> +class DebugEpochBase {
>> + uint64_t Epoch;
>> +
>> +public:
>> + DebugEpochBase() : Epoch(0) {}
>> +
>> + /// \brief Calling incrementEpoch invalidates all handles pointing into the
>> + /// calling instance.
>> + void incrementEpoch() { ++Epoch; }
>> +
>> + /// \brief The destructor calls incrementEpoch to make use-after-free bugs
>> + /// more likely to crash deterministically.
>> + ~DebugEpochBase() { incrementEpoch(); }
>> +
>> + /// \brief A base class for iterator classes ("handles") that wish to poll for
>> + /// iterator invalidating modifications in the underlying data structure.
>> + /// When LLVM is built without asserts, this class is empty and does
>> nothing.
>> + ///
>> + /// HandleBase does not track the parent data structure by itself. It
>> expects
>> + /// the routines modifying the data structure to call incrementEpoch when
>> they
>> + /// make an iterator-invalidating modification.
>> + ///
>> + class HandleBase {
>> + const uint64_t *EpochAddress;
>> + uint64_t EpochAtCreation;
>> +
>> + public:
>> + HandleBase() : EpochAddress(nullptr), EpochAtCreation(UINT64_MAX) {}
>> +
>> + explicit HandleBase(const DebugEpochBase *Parent)
>> + : EpochAddress(&Parent->Epoch), EpochAtCreation(Parent->Epoch) {}
>> +
>> + /// \brief Returns true if the DebugEpochBase this Handle is linked to has
>> + /// not called incrementEpoch on itself since the creation of this
>> + /// HandleBase instance.
>> + bool isHandleInSync() const { return *EpochAddress == EpochAtCreation;
>> }
>> +
>> + /// \brief Returns a pointer to the epoch word stored in the data
>> structure
>> + /// this handle points into. Can be used to check if two iterators point
>> + /// into the same data structure.
>> + const void *getEpochAddress() const { return EpochAddress; }
>> + };
>> +};
>> +
>> +#endif // LLVM_ENABLE_ABI_BREAKING_CHECKS
>> +
>> +} // namespace llvm
>> +
>> +#endif
>>
>> Modified: llvm/trunk/include/llvm/Config/config.h.in
>> URL: http://llvm.org/viewvc/llvm-
>> project/llvm/trunk/include/llvm/Config/config.h.in?rev=233310&r1=233309&
>> r2=233310&view=diff
>> ==========================================================
>> ====================
>> --- llvm/trunk/include/llvm/Config/config.h.in (original)
>> +++ llvm/trunk/include/llvm/Config/config.h.in Thu Mar 26 14:25:01 2015
>> @@ -417,6 +417,9 @@
>> /* Installation directory for documentation */
>> #undef LLVM_DOCSDIR
>>
>> +/* Define to enable checks that alter the LLVM C++ ABI */
>> +#undef LLVM_ENABLE_ABI_BREAKING_CHECKS
>> +
>> /* Define if threads enabled */
>> #undef LLVM_ENABLE_THREADS
>>
>>
>> Modified: llvm/trunk/include/llvm/Config/llvm-config.h.cmake
>> URL: http://llvm.org/viewvc/llvm-
>> project/llvm/trunk/include/llvm/Config/llvm-
>> config.h.cmake?rev=233310&r1=233309&r2=233310&view=diff
>> ==========================================================
>> ====================
>> --- llvm/trunk/include/llvm/Config/llvm-config.h.cmake (original)
>> +++ llvm/trunk/include/llvm/Config/llvm-config.h.cmake Thu Mar 26 14:25:01
>> 2015
>> @@ -101,4 +101,8 @@
>> /* Define if we link Polly to the tools */
>> #cmakedefine LINK_POLLY_INTO_TOOLS
>>
>> +/* Define if LLVM is built with asserts and checks that change the layout of
>> + client-visible data structures. */
>> +#cmakedefine LLVM_ENABLE_ABI_BREAKING_CHECKS
>> +
>> #endif
>>
>> Modified: llvm/trunk/include/llvm/Config/llvm-config.h.in
>> URL: http://llvm.org/viewvc/llvm-
>> project/llvm/trunk/include/llvm/Config/llvm-
>> config.h.in?rev=233310&r1=233309&r2=233310&view=diff
>> ==========================================================
>> ====================
>> --- llvm/trunk/include/llvm/Config/llvm-config.h.in (original)
>> +++ llvm/trunk/include/llvm/Config/llvm-config.h.in Thu Mar 26 14:25:01
>> 2015
>> @@ -98,4 +98,7 @@
>> /* LLVM version string */
>> #undef LLVM_VERSION_STRING
>>
>> +/* Define to enable checks that alter the LLVM C++ ABI */
>> +#undef LLVM_ENABLE_ABI_BREAKING_CHECKS
>> +
>> #endif
>>
>>
>> _______________________________________________
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>> llvm-commits at cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
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