[llvm] r301196 - Compute safety information in a much finer granularity.
Xin Tong via llvm-commits
llvm-commits at lists.llvm.org
Mon Apr 24 11:38:58 PDT 2017
Thanks. I will take a look.
-Xin
On Mon, Apr 24, 2017 at 11:38 AM, Evgenii Stepanov
<eugeni.stepanov at gmail.com> wrote:
> Verified and reverted.
>
> On Mon, Apr 24, 2017 at 11:34 AM, Evgenii Stepanov
> <eugeni.stepanov at gmail.com> wrote:
>> Hi,
>>
>> this must be yours. It it flakily crashing check-msan target on
>> Linux/x86_64. To reproduce, opt -O3 the attached IR file.
>>
>> ==50569==ERROR: AddressSanitizer: heap-use-after-free on address
>> 0x60e0000808f8 at pc 0x000000ccf4e2 bp 0x7ffe16d0e8c0 sp
>> 0x7ffe16d0e8b8
>> READ of size 8 at 0x60e0000808f8 thread T0
>> #0 0xccf4e1 in llvm::Instruction::getParent() const
>> /code/llvm/include/llvm/IR/Instruction.h:62:55
>> #1 0x30cbbb5 in llvm::DominatorTree::dominates(llvm::Instruction
>> const*, llvm::Instruction const*) const
>> /code/llvm/lib/IR/Dominators.cpp:90:35
>> #2 0x3cd60f2 in llvm::isGuaranteedToExecute(llvm::Instruction
>> const&, llvm::DominatorTree const*, llvm::Loop const*,
>> llvm::LoopSafetyInfo const*)
>> /code/llvm/lib/Transforms/Utils/LoopUtils.cpp:1050:14
>> #3 0x390bdd4 in (anonymous
>> namespace)::LoopUnswitch::processCurrentLoop()
>> /code/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp:652:10
>> #4 0x390a555 in (anonymous
>> namespace)::LoopUnswitch::runOnLoop(llvm::Loop*, llvm::LPPassManager&)
>> /code/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp:518:16
>> #5 0x265efc3 in
>> llvm::LPPassManager::runOnFunction(llvm::Function&)
>> /code/llvm/lib/Analysis/LoopPass.cpp:203:23
>> #6 0x3157d2b in
>> llvm::FPPassManager::runOnFunction(llvm::Function&)
>> /code/llvm/lib/IR/LegacyPassManager.cpp:1513:27
>> #7 0x24efdb2 in (anonymous
>> namespace)::CGPassManager::RunPassOnSCC(llvm::Pass*,
>> llvm::CallGraphSCC&, llvm::CallGraph&, bool&, bool&)
>> /code/llvm/lib/Analysis/CallGraphSCCPass.cpp:149:25
>> #8 0x24ef78b in (anonymous
>> namespace)::CGPassManager::RunAllPassesOnSCC(llvm::CallGraphSCC&,
>> llvm::CallGraph&, bool&)
>> /code/llvm/lib/Analysis/CallGraphSCCPass.cpp:417:16
>> #9 0x24eee8b in (anonymous
>> namespace)::CGPassManager::runOnModule(llvm::Module&)
>> /code/llvm/lib/Analysis/CallGraphSCCPass.cpp:473:18
>> #10 0x31588cc in (anonymous
>> namespace)::MPPassManager::runOnModule(llvm::Module&)
>> /code/llvm/lib/IR/LegacyPassManager.cpp:1590:27
>> #11 0x3158385 in llvm::legacy::PassManagerImpl::run(llvm::Module&)
>> /code/llvm/lib/IR/LegacyPassManager.cpp:1693:44
>> #12 0xc69ebf in main /code/llvm/tools/opt/opt.cpp:738:10
>> #13 0x7f34fc5c0f44 in __libc_start_main
>> /build/eglibc-MjiXCM/eglibc-2.19/csu/libc-start.c:287
>> #14 0xb602c4 in _start (/code/build-llvm-asan/bin/opt+0xb602c4)
>>
>> 0x60e0000808f8 is located 120 bytes inside of 152-byte region
>> [0x60e000080880,0x60e000080918)
>> freed by thread T0 here:
>> #0 0xc2fcc2 in operator delete(void*)
>> /code/llvm/projects/compiler-rt/lib/asan/asan_new_delete.cc:126:3
>> #1 0x107cff9 in
>> llvm::iplist_impl<llvm::simple_ilist<llvm::Instruction>,
>> llvm::SymbolTableListTraits<llvm::Instruction>
>>>::erase(llvm::ilist_iterator<llvm::ilist_detail::node_options<llvm::Instruction,
>> true, false, void>, false, false>)
>> /code/llvm/include/llvm/ADT/ilist.h:281:5
>> #2 0x2fa5a7c in
>> llvm::iplist_impl<llvm::simple_ilist<llvm::Instruction>,
>> llvm::SymbolTableListTraits<llvm::Instruction>
>>>::erase(llvm::ilist_iterator<llvm::ilist_detail::node_options<llvm::Instruction,
>> true, false, void>, false, false>,
>> llvm::ilist_iterator<llvm::ilist_detail::node_options<llvm::Instruction,
>> true, false, void>, false, false>)
>> /code/llvm/include/llvm/ADT/ilist.h:318:15
>> #3 0x2fa17f7 in llvm::BasicBlock::~BasicBlock()
>> /code/llvm/lib/IR/BasicBlock.cpp:85:12
>> #4 0x2fa1a0d in llvm::BasicBlock::~BasicBlock()
>> /code/llvm/lib/IR/BasicBlock.cpp:64:27
>> #5 0x2fa4a59 in
>> llvm::iplist_impl<llvm::simple_ilist<llvm::BasicBlock>,
>> llvm::SymbolTableListTraits<llvm::BasicBlock>
>>>::erase(llvm::ilist_iterator<llvm::ilist_detail::node_options<llvm::BasicBlock,
>> true, false, void>, false, false>)
>> /code/llvm/include/llvm/ADT/ilist.h:281:5
>> #6 0x3ca62a2 in llvm::removeUnreachableBlocks(llvm::Function&,
>> llvm::LazyValueInfo*)
>> /code/llvm/lib/Transforms/Utils/Local.cpp:1725:33
>> #7 0x3a2a34c in simplifyFunctionCFG(llvm::Function&,
>> llvm::TargetTransformInfo const&, llvm::AssumptionCache*, int, bool)
>> /code/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp:162:22
>> #8 0x3157d2b in
>> llvm::FPPassManager::runOnFunction(llvm::Function&)
>> /code/llvm/lib/IR/LegacyPassManager.cpp:1513:27
>> #9 0x24efdb2 in (anonymous
>> namespace)::CGPassManager::RunPassOnSCC(llvm::Pass*,
>> llvm::CallGraphSCC&, llvm::CallGraph&, bool&, bool&)
>> /code/llvm/lib/Analysis/CallGraphSCCPass.cpp:149:25
>> #10 0x24ef78b in (anonymous
>> namespace)::CGPassManager::RunAllPassesOnSCC(llvm::CallGraphSCC&,
>> llvm::CallGraph&, bool&)
>> /code/llvm/lib/Analysis/CallGraphSCCPass.cpp:417:16
>> #11 0x24eee8b in (anonymous
>> namespace)::CGPassManager::runOnModule(llvm::Module&)
>> /code/llvm/lib/Analysis/CallGraphSCCPass.cpp:473:18
>> #12 0x31588cc in (anonymous
>> namespace)::MPPassManager::runOnModule(llvm::Module&)
>> /code/llvm/lib/IR/LegacyPassManager.cpp:1590:27
>> #13 0x3158385 in llvm::legacy::PassManagerImpl::run(llvm::Module&)
>> /code/llvm/lib/IR/LegacyPassManager.cpp:1693:44
>> #14 0xc69ebf in main /code/llvm/tools/opt/opt.cpp:738:10
>> #15 0x7f34fc5c0f44 in __libc_start_main
>> /build/eglibc-MjiXCM/eglibc-2.19/csu/libc-start.c:287
>>
>> previously allocated by thread T0 here:
>> #0 0xc2f0c2 in operator new(unsigned long)
>> /code/llvm/projects/compiler-rt/lib/asan/asan_new_delete.cc:82:35
>> #1 0x3202025 in llvm::User::allocateFixedOperandUser(unsigned
>> long, unsigned int, unsigned int) /code/llvm/lib/IR/User.cpp:128:7
>> #2 0x3202025 in llvm::User::operator new(unsigned long, unsigned
>> int) /code/llvm/lib/IR/User.cpp:146
>> #3 0x3122ce8 in llvm::CallInst::cloneImpl() const
>> /code/llvm/lib/IR/Instructions.cpp:3955:11
>> #4 0x310ab55 in llvm::Instruction::clone() const
>> /code/llvm/include/llvm/IR/Instruction.def:186:1
>> #5 0x3c345bf in llvm::CloneBasicBlock(llvm::BasicBlock const*,
>> llvm::ValueMap<llvm::Value const*, llvm::WeakVH,
>> llvm::ValueMapConfig<llvm::Value const*, llvm::sys::SmartMutex<false>
>>> >&, llvm::Twine const&, llvm::Function*, llvm::ClonedCodeInfo*)
>> /code/llvm/lib/Transforms/Utils/CloneFunction.cpp:52:32
>> #6 0x39129f7 in (anonymous
>> namespace)::LoopUnswitch::UnswitchNontrivialCondition(llvm::Value*,
>> llvm::Constant*, llvm::Loop*, llvm::TerminatorInst*)
>> /code/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp:1148:25
>> #7 0x390ddf7 in (anonymous
>> namespace)::LoopUnswitch::UnswitchIfProfitable(llvm::Value*,
>> llvm::Constant*, llvm::TerminatorInst*)
>> /code/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp:826:3
>> #8 0x390c004 in (anonymous
>> namespace)::LoopUnswitch::processCurrentLoop()
>> /code/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp:670:13
>> #9 0x390a555 in (anonymous
>> namespace)::LoopUnswitch::runOnLoop(llvm::Loop*, llvm::LPPassManager&)
>> /code/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp:518:16
>> #10 0x265efc3 in
>> llvm::LPPassManager::runOnFunction(llvm::Function&)
>> /code/llvm/lib/Analysis/LoopPass.cpp:203:23
>> #11 0x3157d2b in
>> llvm::FPPassManager::runOnFunction(llvm::Function&)
>> /code/llvm/lib/IR/LegacyPassManager.cpp:1513:27
>> #12 0x24efdb2 in (anonymous
>> namespace)::CGPassManager::RunPassOnSCC(llvm::Pass*,
>> llvm::CallGraphSCC&, llvm::CallGraph&, bool&, bool&)
>> /code/llvm/lib/Analysis/CallGraphSCCPass.cpp:149:25
>> #13 0x24ef78b in (anonymous
>> namespace)::CGPassManager::RunAllPassesOnSCC(llvm::CallGraphSCC&,
>> llvm::CallGraph&, bool&)
>> /code/llvm/lib/Analysis/CallGraphSCCPass.cpp:417:16
>> #14 0x24eee8b in (anonymous
>> namespace)::CGPassManager::runOnModule(llvm::Module&)
>> /code/llvm/lib/Analysis/CallGraphSCCPass.cpp:473:18
>> #15 0x31588cc in (anonymous
>> namespace)::MPPassManager::runOnModule(llvm::Module&)
>> /code/llvm/lib/IR/LegacyPassManager.cpp:1590:27
>> #16 0x3158385 in llvm::legacy::PassManagerImpl::run(llvm::Module&)
>> /code/llvm/lib/IR/LegacyPassManager.cpp:1693:44
>> #17 0xc69ebf in main /code/llvm/tools/opt/opt.cpp:738:10
>> #18 0x7f34fc5c0f44 in __libc_start_main
>> /build/eglibc-MjiXCM/eglibc-2.19/csu/libc-start.c:287
>>
>> SUMMARY: AddressSanitizer: heap-use-after-free
>> /code/llvm/include/llvm/IR/Instruction.h:62:55 in
>> llvm::Instruction::getParent() const
>> Shadow bytes around the buggy address:
>> 0x0c1c800080c0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fa
>> 0x0c1c800080d0: fa fa fa fa fa fa fa fa fd fd fd fd fd fd fd fd
>> 0x0c1c800080e0: fd fd fd fd fd fd fd fd fd fd fd fd fa fa fa fa
>> 0x0c1c800080f0: fa fa fa fa fd fd fd fd fd fd fd fd fd fd fd fd
>> 0x0c1c80008100: fd fd fd fd fd fd fd fd fa fa fa fa fa fa fa fa
>> =>0x0c1c80008110: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd[fd]
>> 0x0c1c80008120: fd fd fd fa fa fa fa fa fa fa fa fa fd fd fd fd
>> 0x0c1c80008130: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
>> 0x0c1c80008140: fa fa fa fa fa fa fa fa fd fd fd fd fd fd fd fd
>> 0x0c1c80008150: fd fd fd fd fd fd fd fd fd fd fd fd fa fa fa fa
>> 0x0c1c80008160: fa fa fa fa fd fd fd fd fd fd fd fd fd fd fd fd
>> Shadow byte legend (one shadow byte represents 8 application bytes):
>> Addressable: 00
>> Partially addressable: 01 02 03 04 05 06 07
>> Heap left redzone: fa
>> Freed heap region: fd
>> Stack left redzone: f1
>> Stack mid redzone: f2
>> Stack right redzone: f3
>> Stack after return: f5
>> Stack use after scope: f8
>> Global redzone: f9
>> Global init order: f6
>> Poisoned by user: f7
>> Container overflow: fc
>> Array cookie: ac
>> Intra object redzone: bb
>> ASan internal: fe
>> Left alloca redzone: ca
>> Right alloca redzone: cb
>>
>>
>>
>>
>> On Mon, Apr 24, 2017 at 10:12 AM, Xin Tong via llvm-commits
>> <llvm-commits at lists.llvm.org> wrote:
>>> Author: trentxintong
>>> Date: Mon Apr 24 12:12:22 2017
>>> New Revision: 301196
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=301196&view=rev
>>> Log:
>>> Compute safety information in a much finer granularity.
>>>
>>> Summary:
>>> Instead of keeping a variable indicating whether there are early exits
>>> in the loop. We keep all the early exits. This improves LICM's ability to
>>> move instructions out of the loop based on is-guaranteed-to-execute.
>>>
>>> I am going to update compilation time as well soon.
>>>
>>> Reviewers: hfinkel, sanjoy, efriedma, mkuper
>>>
>>> Reviewed By: hfinkel
>>>
>>> Subscribers: llvm-commits, mzolotukhin
>>>
>>> Differential Revision: https://reviews.llvm.org/D32433
>>>
>>> Added:
>>> llvm/trunk/test/Transforms/LICM/loop-early-exits.ll
>>> Modified:
>>> llvm/trunk/include/llvm/Transforms/Utils/LoopUtils.h
>>> llvm/trunk/lib/Transforms/Scalar/LICM.cpp
>>> llvm/trunk/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
>>> llvm/trunk/lib/Transforms/Utils/LoopUtils.cpp
>>> llvm/trunk/test/Transforms/LICM/preheader-safe.ll
>>>
>>> Modified: llvm/trunk/include/llvm/Transforms/Utils/LoopUtils.h
>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Utils/LoopUtils.h?rev=301196&r1=301195&r2=301196&view=diff
>>> ==============================================================================
>>> --- llvm/trunk/include/llvm/Transforms/Utils/LoopUtils.h (original)
>>> +++ llvm/trunk/include/llvm/Transforms/Utils/LoopUtils.h Mon Apr 24 12:12:22 2017
>>> @@ -46,9 +46,9 @@ class TargetLibraryInfo;
>>> /// \brief Captures loop safety information.
>>> /// It keep information for loop & its header may throw exception.
>>> struct LoopSafetyInfo {
>>> - bool MayThrow = false; // The current loop contains an instruction which
>>> - // may throw.
>>> - bool HeaderMayThrow = false; // Same as previous, but specific to loop header
>>> + // The early exits in the loop, excluding loop exits.
>>> + // These are calls that might throw, infinite loop, etc.
>>> + SmallVector<Instruction *, 4> EarlyExits;
>>> // Used to update funclet bundle operands.
>>> DenseMap<BasicBlock *, ColorVector> BlockColors;
>>>
>>>
>>> Modified: llvm/trunk/lib/Transforms/Scalar/LICM.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LICM.cpp?rev=301196&r1=301195&r2=301196&view=diff
>>> ==============================================================================
>>> --- llvm/trunk/lib/Transforms/Scalar/LICM.cpp (original)
>>> +++ llvm/trunk/lib/Transforms/Scalar/LICM.cpp Mon Apr 24 12:12:22 2017
>>> @@ -478,27 +478,17 @@ bool llvm::hoistRegion(DomTreeNode *N, A
>>> ///
>>> void llvm::computeLoopSafetyInfo(LoopSafetyInfo *SafetyInfo, Loop *CurLoop) {
>>> assert(CurLoop != nullptr && "CurLoop cant be null");
>>> - BasicBlock *Header = CurLoop->getHeader();
>>> - // Setting default safety values.
>>> - SafetyInfo->MayThrow = false;
>>> - SafetyInfo->HeaderMayThrow = false;
>>> - // Iterate over header and compute safety info.
>>> - for (BasicBlock::iterator I = Header->begin(), E = Header->end();
>>> - (I != E) && !SafetyInfo->HeaderMayThrow; ++I)
>>> - SafetyInfo->HeaderMayThrow |=
>>> - !isGuaranteedToTransferExecutionToSuccessor(&*I);
>>> -
>>> - SafetyInfo->MayThrow = SafetyInfo->HeaderMayThrow;
>>> - // Iterate over loop instructions and compute safety info.
>>> - // Skip header as it has been computed and stored in HeaderMayThrow.
>>> - // The first block in loopinfo.Blocks is guaranteed to be the header.
>>> - assert(Header == *CurLoop->getBlocks().begin() && "First block must be header");
>>> - for (Loop::block_iterator BB = std::next(CurLoop->block_begin()),
>>> + // Iterate over loop instructions and compute early exit points.
>>> + for (Loop::block_iterator BB = CurLoop->block_begin(),
>>> BBE = CurLoop->block_end();
>>> - (BB != BBE) && !SafetyInfo->MayThrow; ++BB)
>>> - for (BasicBlock::iterator I = (*BB)->begin(), E = (*BB)->end();
>>> - (I != E) && !SafetyInfo->MayThrow; ++I)
>>> - SafetyInfo->MayThrow |= !isGuaranteedToTransferExecutionToSuccessor(&*I);
>>> + BB != BBE; ++BB) {
>>> + for (BasicBlock::iterator I = (*BB)->begin(), E = (*BB)->end(); I != E;
>>> + ++I) {
>>> + if (isGuaranteedToTransferExecutionToSuccessor(&*I))
>>> + continue;
>>> + SafetyInfo->EarlyExits.push_back(&*I);
>>> + }
>>> + }
>>>
>>> // Compute funclet colors if we might sink/hoist in a function with a funclet
>>> // personality routine.
>>> @@ -1094,7 +1084,7 @@ bool llvm::promoteLoopAccessesToScalars(
>>>
>>> // Do we know this object does not escape ?
>>> bool IsKnownNonEscapingObject = false;
>>> - if (SafetyInfo->MayThrow) {
>>> + if (!SafetyInfo->EarlyExits.empty()) {
>>> // If a loop can throw, we have to insert a store along each unwind edge.
>>> // That said, we can't actually make the unwind edge explicit. Therefore,
>>> // we have to prove that the store is dead along the unwind edge.
>>>
>>> Modified: llvm/trunk/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopIdiomRecognize.cpp?rev=301196&r1=301195&r2=301196&view=diff
>>> ==============================================================================
>>> --- llvm/trunk/lib/Transforms/Scalar/LoopIdiomRecognize.cpp (original)
>>> +++ llvm/trunk/lib/Transforms/Scalar/LoopIdiomRecognize.cpp Mon Apr 24 12:12:22 2017
>>> @@ -272,7 +272,7 @@ bool LoopIdiomRecognize::runOnCountableL
>>> // Give up if the loop has instructions may throw.
>>> LoopSafetyInfo SafetyInfo;
>>> computeLoopSafetyInfo(&SafetyInfo, CurLoop);
>>> - if (SafetyInfo.MayThrow)
>>> + if (!SafetyInfo.EarlyExits.empty())
>>> return MadeChange;
>>>
>>> // Scan all the blocks in the loop that are not in subloops.
>>>
>>> Modified: llvm/trunk/lib/Transforms/Utils/LoopUtils.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/LoopUtils.cpp?rev=301196&r1=301195&r2=301196&view=diff
>>> ==============================================================================
>>> --- llvm/trunk/lib/Transforms/Utils/LoopUtils.cpp (original)
>>> +++ llvm/trunk/lib/Transforms/Utils/LoopUtils.cpp Mon Apr 24 12:12:22 2017
>>> @@ -1044,21 +1044,11 @@ bool llvm::isGuaranteedToExecute(const I
>>> const DominatorTree *DT, const Loop *CurLoop,
>>> const LoopSafetyInfo *SafetyInfo) {
>>> // We have to check to make sure that the instruction dominates all
>>> - // of the exit blocks. If it doesn't, then there is a path out of the loop
>>> - // which does not execute this instruction, so we can't hoist it.
>>> -
>>> - // If the instruction is in the header block for the loop (which is very
>>> - // common), it is always guaranteed to dominate the exit blocks. Since this
>>> - // is a common case, and can save some work, check it now.
>>> - if (Inst.getParent() == CurLoop->getHeader())
>>> - // If there's a throw in the header block, we can't guarantee we'll reach
>>> - // Inst.
>>> - return !SafetyInfo->HeaderMayThrow;
>>> -
>>> - // Somewhere in this loop there is an instruction which may throw and make us
>>> - // exit the loop.
>>> - if (SafetyInfo->MayThrow)
>>> - return false;
>>> + // of the exit points. If it doesn't, then there is a path out of the loop
>>> + // which does not execute this instruction and its not guaranteed to execute.
>>> + for (Instruction *ExitInst : SafetyInfo->EarlyExits)
>>> + if (!DT->dominates(&Inst, ExitInst))
>>> + return false;
>>>
>>> // Get the exit blocks for the current loop.
>>> SmallVector<BasicBlock *, 8> ExitBlocks;
>>> @@ -1071,7 +1061,9 @@ bool llvm::isGuaranteedToExecute(const I
>>>
>>> // As a degenerate case, if the loop is statically infinite then we haven't
>>> // proven anything since there are no exit blocks.
>>> - if (ExitBlocks.empty())
>>> + // However, we also special case instruction from the header as the header
>>> + // is always guaranteed to execute.
>>> + if (ExitBlocks.empty() && Inst.getParent() != CurLoop->getHeader())
>>> return false;
>>>
>>> // FIXME: In general, we have to prove that the loop isn't an infinite loop.
>>>
>>> Added: llvm/trunk/test/Transforms/LICM/loop-early-exits.ll
>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LICM/loop-early-exits.ll?rev=301196&view=auto
>>> ==============================================================================
>>> --- llvm/trunk/test/Transforms/LICM/loop-early-exits.ll (added)
>>> +++ llvm/trunk/test/Transforms/LICM/loop-early-exits.ll Mon Apr 24 12:12:22 2017
>>> @@ -0,0 +1,82 @@
>>> +; RUN: opt -S -licm < %s | FileCheck %s
>>> +
>>> +declare void @use(i64 %a)
>>> +declare void @use_nothrow(i64 %a) nounwind
>>> +declare void @use_nothing()
>>> +
>>> +; We can move this udiv out of the loop as it comes before
>>> +; the call instruction that may throw.
>>> +define void @throw_header1(i64 %x, i64 %y, i1* %cond) {
>>> +; CHECK-LABEL: throw_header1
>>> +; CHECK: %div = udiv i64 %x, %y
>>> +; CHECK-LABEL: loop
>>> +; CHECK: call void @use(i64 %div)
>>> +entry:
>>> + br label %loop
>>> +
>>> +loop: ; preds = %entry, %for.inc
>>> + %div = udiv i64 %x, %y
>>> + call void @use(i64 %div)
>>> + br label %loop
>>> +}
>>> +
>>> +; We can not move this udiv out of the loop as it comes after
>>> +; the call instruction that may throw.
>>> +define void @throw_header2(i64 %x, i64 %y, i1* %cond) {
>>> +; CHECK-LABEL: throw_header2
>>> +; CHECK-LABEL: loop
>>> +; CHECK: call void @use_nothing()
>>> +; CHECK: %div = udiv i64 %x, %y
>>> +entry:
>>> + br label %loop
>>> +
>>> +loop: ; preds = %entry, %for.inc
>>> + call void @use_nothing()
>>> + %div = udiv i64 %x, %y
>>> + call void @use_nothrow(i64 %div)
>>> + br label %loop
>>> +}
>>> +
>>> +; We can move this udiv out of the loop as it comes before
>>> +; the call instruction that may throw.
>>> +define void @throw_body1(i64 %x, i64 %y, i1* %cond) {
>>> +; CHECK-LABEL: throw_body1
>>> +; CHECK: %div = udiv i64 %x, %y
>>> +; CHECK-LABEL: loop
>>> +entry:
>>> + br label %loop
>>> +
>>> +loop: ; preds = %entry, %for.inc
>>> + br label %body
>>> +
>>> +body:
>>> + %div = udiv i64 %x, %y
>>> + call void @use(i64 %div)
>>> + br i1 undef, label %loop, label %exit
>>> +
>>> +exit:
>>> + ret void
>>> +}
>>> +
>>> +; We can not move this udiv out of the loop as it comes after
>>> +; the call instruction that may throw.
>>> +define void @throw_body2(i64 %x, i64 %y, i1* %cond) {
>>> +; CHECK-LABEL: throw_body2
>>> +; CHECK-LABEL: loop
>>> +; CHECK: call void @use_nothing()
>>> +; CHECK: %div = udiv i64 %x, %y
>>> +entry:
>>> + br label %loop
>>> +
>>> +loop: ; preds = %entry, %for.inc
>>> + br label %body
>>> +
>>> +body:
>>> + call void @use_nothing()
>>> + %div = udiv i64 %x, %y
>>> + call void @use_nothrow(i64 %div)
>>> + br i1 undef, label %loop, label %exit
>>> +
>>> +exit:
>>> + ret void
>>> +}
>>>
>>> Modified: llvm/trunk/test/Transforms/LICM/preheader-safe.ll
>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LICM/preheader-safe.ll?rev=301196&r1=301195&r2=301196&view=diff
>>> ==============================================================================
>>> --- llvm/trunk/test/Transforms/LICM/preheader-safe.ll (original)
>>> +++ llvm/trunk/test/Transforms/LICM/preheader-safe.ll Mon Apr 24 12:12:22 2017
>>> @@ -21,20 +21,6 @@ loop2:
>>> call void @use_nothrow(i64 %div)
>>> br label %loop
>>> }
>>> -; Negative test
>>> -define void @throw_header(i64 %x, i64 %y, i1* %cond) {
>>> -; CHECK-LABEL: throw_header
>>> -; CHECK-LABEL: loop
>>> -; CHECK: %div = udiv i64 %x, %y
>>> -; CHECK: call void @use(i64 %div)
>>> -entry:
>>> - br label %loop
>>> -
>>> -loop: ; preds = %entry, %for.inc
>>> - %div = udiv i64 %x, %y
>>> - call void @use(i64 %div)
>>> - br label %loop
>>> -}
>>>
>>> ; The header is known no throw, but the loop is not. We can
>>> ; still lift out of the header.
>>>
>>>
>>> _______________________________________________
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>>> llvm-commits at lists.llvm.org
>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
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