[llvm] r301196 - Compute safety information in a much finer granularity.
Evgenii Stepanov via llvm-commits
llvm-commits at lists.llvm.org
Mon Apr 24 11:34:42 PDT 2017
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.
>
>
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
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