[llvm] r303497 - [SCEV] Clarify behavior around max backedge taken count
Sanjoy Das via llvm-commits
llvm-commits at lists.llvm.org
Sat May 20 22:02:44 PDT 2017
Reverted in r303498
On Sat, May 20, 2017 at 9:59 PM, Sanjoy Das
<sanjoy at playingwithpointers.com> wrote:
> Hi Vitaly,
>
> I'm about to revert this change, but I have a question -- what this
> failure seen when the ToT clang (built with a "known good" clang +
> msan) tried to build itself, or when a bootstrapped clang (i.e. a
> clang built with a ToT clang + msan) tried to bootstrap itself?
>
> Thanks
> -- Sanjoy
>
> On Sat, May 20, 2017 at 9:49 PM, Vitaly Buka <vitalybuka at google.com> wrote:
>> http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-bootstrap/builds/1379/steps/check-llvm%20check-clang%20stage3%2Fmsan/logs/stdio
>>
>> FAILED: tools/llvm-xray/CMakeFiles/llvm-xray.dir/xray-color-helper.cc.o
>> /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm_build_msan/bin/clang++
>> -DGTEST_HAS_RTTI=0 -DLLVM_BUILD_GLOBAL_ISEL -D_DEBUG -D_GNU_SOURCE
>> -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS
>> -Itools/llvm-xray
>> -I/mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/tools/llvm-xray
>> -Iinclude
>> -I/mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/include
>> -fPIC -fvisibility-inlines-hidden -Werror=date-time -std=c++11 -Wall -W
>> -Wno-unused-parameter -Wwrite-strings -Wcast-qual
>> -Wmissing-field-initializers -pedantic -Wno-long-long
>> -Wcovered-switch-default -Wnon-virtual-dtor -Wdelete-non-virtual-dtor
>> -Wstring-conversion -fcolor-diagnostics -ffunction-sections -fdata-sections
>> -O3 -UNDEBUG -fno-exceptions -fno-rtti -MD -MT
>> tools/llvm-xray/CMakeFiles/llvm-xray.dir/xray-color-helper.cc.o -MF
>> tools/llvm-xray/CMakeFiles/llvm-xray.dir/xray-color-helper.cc.o.d -o
>> tools/llvm-xray/CMakeFiles/llvm-xray.dir/xray-color-helper.cc.o -c
>> /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/tools/llvm-xray/xray-color-helper.cc
>> ==969==WARNING: MemorySanitizer: use-of-uninitialized-value
>> #0 0x3533258 in
>> llvm::X86InstrInfo::AnalyzeBranchImpl(llvm::MachineBasicBlock&,
>> llvm::MachineBasicBlock*&, llvm::MachineBasicBlock*&,
>> llvm::SmallVectorImpl<llvm::MachineOperand>&,
>> llvm::SmallVectorImpl<llvm::MachineInstr*>&, bool) const
>> /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/lib/Target/X86/X86InstrInfo.cpp:6093:22
>> #1 0x353333d in
>> llvm::X86InstrInfo::analyzeBranch(llvm::MachineBasicBlock&,
>> llvm::MachineBasicBlock*&, llvm::MachineBasicBlock*&,
>> llvm::SmallVectorImpl<llvm::MachineOperand>&, bool) const
>> /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/lib/Target/X86/X86InstrInfo.cpp:6133:10
>> #2 0x42fddcc in llvm::TailDuplicator::tailDuplicate(bool,
>> llvm::MachineBasicBlock*, llvm::MachineBasicBlock*,
>> llvm::SmallVectorImpl<llvm::MachineBasicBlock*>&,
>> llvm::SmallVectorImpl<llvm::MachineInstr*>&)
>> /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/lib/CodeGen/TailDuplicator.cpp:837:10
>> #3 0x42fab3a in llvm::TailDuplicator::tailDuplicateAndUpdate(bool,
>> llvm::MachineBasicBlock*, llvm::MachineBasicBlock*,
>> llvm::SmallVectorImpl<llvm::MachineBasicBlock*>*, llvm::function_ref<void
>> (llvm::MachineBasicBlock*)>*)
>> /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/lib/CodeGen/TailDuplicator.cpp:148:8
>> #4 0x44e921b in (anonymous
>> namespace)::MachineBlockPlacement::maybeTailDuplicateBlock(llvm::MachineBasicBlock*,
>> llvm::MachineBasicBlock*, (anonymous namespace)::BlockChain&,
>> llvm::SmallSetVector<llvm::MachineBasicBlock const*, 16u>*,
>> llvm::ilist_iterator<llvm::ilist_detail::node_options<llvm::MachineBasicBlock,
>> true, false, void>, false, false>&, bool&)
>> /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/lib/CodeGen/MachineBlockPlacement.cpp:2620:11
>> #5 0x44cef5d in repeatedlyTailDuplicateBlock
>> /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/lib/CodeGen/MachineBlockPlacement.cpp:2501:13
>> #6 0x44cef5d in (anonymous
>> namespace)::MachineBlockPlacement::buildChain(llvm::MachineBasicBlock
>> const*, (anonymous namespace)::BlockChain&,
>> llvm::SmallSetVector<llvm::MachineBasicBlock const*, 16u>*)
>> /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/lib/CodeGen/MachineBlockPlacement.cpp:1699
>> #7 0x44b6970 in (anonymous
>> namespace)::MachineBlockPlacement::buildCFGChains()
>> /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/lib/CodeGen/MachineBlockPlacement.cpp:2278:3
>> #8 0x44b14a9 in (anonymous
>> namespace)::MachineBlockPlacement::runOnMachineFunction(llvm::MachineFunction&)
>> /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/lib/CodeGen/MachineBlockPlacement.cpp:2696:3
>> #9 0x3f6dcac in
>> llvm::MachineFunctionPass::runOnFunction(llvm::Function&)
>> /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/lib/CodeGen/MachineFunctionPass.cpp:62:13
>> #10 0x48e2bee in llvm::FPPassManager::runOnFunction(llvm::Function&)
>> /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/lib/IR/LegacyPassManager.cpp:1519:27
>> #11 0x48e32b4 in llvm::FPPassManager::runOnModule(llvm::Module&)
>> /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/lib/IR/LegacyPassManager.cpp:1540:16
>> #12 0x48e45d3 in runOnModule
>> /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/lib/IR/LegacyPassManager.cpp:1596:27
>> #13 0x48e45d3 in llvm::legacy::PassManagerImpl::run(llvm::Module&)
>> /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/lib/IR/LegacyPassManager.cpp:1699
>> #14 0x5d3e27e in EmitAssembly
>> /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/tools/clang/lib/CodeGen/BackendUtil.cpp:792:19
>> #15 0x5d3e27e in clang::EmitBackendOutput(clang::DiagnosticsEngine&,
>> clang::HeaderSearchOptions const&, clang::CodeGenOptions const&,
>> clang::TargetOptions const&, clang::LangOptions const&, llvm::DataLayout
>> const&, llvm::Module*, clang::BackendAction,
>> std::__1::unique_ptr<llvm::raw_pwrite_stream,
>> std::__1::default_delete<llvm::raw_pwrite_stream> >)
>> /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/tools/clang/lib/CodeGen/BackendUtil.cpp:1101
>> #16 0x74dfefe in
>> clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&)
>> /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/tools/clang/lib/CodeGen/CodeGenAction.cpp:258:7
>> #17 0x848e176 in clang::ParseAST(clang::Sema&, bool, bool)
>> /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/tools/clang/lib/Parse/ParseAST.cpp:159:13
>> #18 0x69f82ba in clang::FrontendAction::Execute()
>> /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/tools/clang/lib/Frontend/FrontendAction.cpp:837:8
>> #19 0x693a02c in
>> clang::CompilerInstance::ExecuteAction(clang::FrontendAction&)
>> /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/tools/clang/lib/Frontend/CompilerInstance.cpp:970:11
>> #20 0x6bc3705 in
>> clang::ExecuteCompilerInvocation(clang::CompilerInstance*)
>> /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/tools/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp:249:25
>> #21 0x976e25 in cc1_main(llvm::ArrayRef<char const*>, char const*,
>> void*)
>> /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/tools/clang/tools/driver/cc1_main.cpp:221:13
>> #22 0x970ce7 in ExecuteCC1Tool
>> /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/tools/clang/tools/driver/driver.cpp:299:12
>> #23 0x970ce7 in main
>> /mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm/tools/clang/tools/driver/driver.cpp:380
>> #24 0x7f561ec5c82f in __libc_start_main
>> (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)
>> #25 0x8f0d38 in _start
>> (/mnt/b/sanitizer-buildbot2/sanitizer-x86_64-linux-bootstrap/build/llvm_build_msan/bin/clang-5.0+0x8f0d38)
>>
>>
>> On Sat, May 20, 2017 at 6:47 PM, Sanjoy Das via llvm-commits
>> <llvm-commits at lists.llvm.org> wrote:
>>>
>>> Author: sanjoy
>>> Date: Sat May 20 20:47:50 2017
>>> New Revision: 303497
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=303497&view=rev
>>> Log:
>>> [SCEV] Clarify behavior around max backedge taken count
>>>
>>> This change makes the split between the "exact" backedge taken count
>>> and the "maximum" backedge taken count a bit more obvious. Both of
>>> these are upper bounds on the number of times the loop header
>>> executes (since SCEV does not account for most kinds of abnormal
>>> control flow), but the latter is guaranteed to be a constant.
>>>
>>> There were a few places where the max backedge taken count *was* a
>>> non-constant; I've changed those to compute constants instead.
>>>
>>> At this point, I'm not sure if the constant max backedge count can be
>>> computed by calling `getUnsignedRange(Exact).getUnsignedMax()` without
>>> losing precision. If it can, we can simplify even further by making
>>> `getMaxBackedgeTakenCount` a thin wrapper around
>>> `getBackedgeTakenCount` and `getUnsignedRange`.
>>>
>>> Modified:
>>> llvm/trunk/include/llvm/Analysis/ScalarEvolution.h
>>> llvm/trunk/lib/Analysis/ScalarEvolution.cpp
>>> llvm/trunk/test/Analysis/ScalarEvolution/nsw.ll
>>> llvm/trunk/test/Analysis/ScalarEvolution/trip-count-pow2.ll
>>>
>>> Modified: llvm/trunk/include/llvm/Analysis/ScalarEvolution.h
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/ScalarEvolution.h?rev=303497&r1=303496&r2=303497&view=diff
>>>
>>> ==============================================================================
>>> --- llvm/trunk/include/llvm/Analysis/ScalarEvolution.h (original)
>>> +++ llvm/trunk/include/llvm/Analysis/ScalarEvolution.h Sat May 20 20:47:50
>>> 2017
>>> @@ -656,10 +656,12 @@ private:
>>> /// Test whether this BackedgeTakenInfo contains complete
>>> information.
>>> bool hasFullInfo() const { return isComplete(); }
>>>
>>> - /// Return an expression indicating the exact backedge-taken count of
>>> the
>>> - /// loop if it is known or SCEVCouldNotCompute otherwise. This is the
>>> - /// number of times the loop header can be guaranteed to execute,
>>> minus
>>> - /// one.
>>> + /// Return an expression indicating the exact *backedge-taken*
>>> + /// count of the loop if it is known or SCEVCouldNotCompute
>>> + /// otherwise. If execution makes it to the backedge on every
>>> + /// iteration (i.e. there are no abnormal exists like exception
>>> + /// throws and thread exits) then this is the number of times the
>>> + /// loop header will execute minus one.
>>> ///
>>> /// If the SCEV predicate associated with the answer can be different
>>> /// from AlwaysTrue, we must add a (non null) Predicates argument.
>>> @@ -1398,11 +1400,11 @@ public:
>>> const SCEV *getExitCount(const Loop *L, BasicBlock *ExitingBlock);
>>>
>>> /// If the specified loop has a predictable backedge-taken count,
>>> return it,
>>> - /// otherwise return a SCEVCouldNotCompute object. The backedge-taken
>>> count
>>> - /// is the number of times the loop header will be branched to from
>>> within
>>> - /// the loop. This is one less than the trip count of the loop, since
>>> it
>>> - /// doesn't count the first iteration, when the header is branched to
>>> from
>>> - /// outside the loop.
>>> + /// otherwise return a SCEVCouldNotCompute object. The backedge-taken
>>> count is
>>> + /// the number of times the loop header will be branched to from within
>>> the
>>> + /// loop, assuming there are no abnormal exists like exception throws.
>>> This is
>>> + /// one less than the trip count of the loop, since it doesn't count
>>> the first
>>> + /// iteration, when the header is branched to from outside the loop.
>>> ///
>>> /// Note that it is not valid to call this method on a loop without a
>>> /// loop-invariant backedge-taken count (see
>>> @@ -1417,8 +1419,10 @@ public:
>>> const SCEV *getPredicatedBackedgeTakenCount(const Loop *L,
>>> SCEVUnionPredicate
>>> &Predicates);
>>>
>>> - /// Similar to getBackedgeTakenCount, except return the least SCEV
>>> value
>>> - /// that is known never to be less than the actual backedge taken
>>> count.
>>> + /// When successful, this returns a SCEVConstant that is greater than
>>> or equal
>>> + /// to (i.e. a "conservative over-approximation") of the value returend
>>> by
>>> + /// getBackedgeTakenCount. If such a value cannot be computed, it
>>> returns the
>>> + /// SCEVCouldNotCompute object.
>>> const SCEV *getMaxBackedgeTakenCount(const Loop *L);
>>>
>>> /// Return true if the backedge taken count is either the value
>>> returned by
>>>
>>> Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=303497&r1=303496&r2=303497&view=diff
>>>
>>> ==============================================================================
>>> --- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
>>> +++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Sat May 20 20:47:50 2017
>>> @@ -5947,6 +5947,8 @@ ScalarEvolution::BackedgeTakenInfo::getM
>>> if (any_of(ExitNotTaken, PredicateNotAlwaysTrue) || !getMax())
>>> return SE->getCouldNotCompute();
>>>
>>> + assert((isa<SCEVCouldNotCompute>(getMax()) ||
>>> isa<SCEVConstant>(getMax())) &&
>>> + "No point in having a non-constant max backedge taken count!");
>>> return getMax();
>>> }
>>>
>>> @@ -5972,7 +5974,11 @@ bool ScalarEvolution::BackedgeTakenInfo:
>>> }
>>>
>>> ScalarEvolution::ExitLimit::ExitLimit(const SCEV *E)
>>> - : ExactNotTaken(E), MaxNotTaken(E), MaxOrZero(false) {}
>>> + : ExactNotTaken(E), MaxNotTaken(E), MaxOrZero(false) {
>>> + assert((isa<SCEVCouldNotCompute>(MaxNotTaken) ||
>>> + isa<SCEVConstant>(MaxNotTaken)) &&
>>> + "No point in having a non-constant max backedge taken count!");
>>> +}
>>>
>>> ScalarEvolution::ExitLimit::ExitLimit(
>>> const SCEV *E, const SCEV *M, bool MaxOrZero,
>>> @@ -5981,6 +5987,9 @@ ScalarEvolution::ExitLimit::ExitLimit(
>>> assert((isa<SCEVCouldNotCompute>(ExactNotTaken) ||
>>> !isa<SCEVCouldNotCompute>(MaxNotTaken)) &&
>>> "Exact is not allowed to be less precise than Max");
>>> + assert((isa<SCEVCouldNotCompute>(MaxNotTaken) ||
>>> + isa<SCEVConstant>(MaxNotTaken)) &&
>>> + "No point in having a non-constant max backedge taken count!");
>>> for (auto *PredSet : PredSetList)
>>> for (auto *P : *PredSet)
>>> addPredicate(P);
>>> @@ -5989,11 +5998,19 @@ ScalarEvolution::ExitLimit::ExitLimit(
>>> ScalarEvolution::ExitLimit::ExitLimit(
>>> const SCEV *E, const SCEV *M, bool MaxOrZero,
>>> const SmallPtrSetImpl<const SCEVPredicate *> &PredSet)
>>> - : ExitLimit(E, M, MaxOrZero, {&PredSet}) {}
>>> + : ExitLimit(E, M, MaxOrZero, {&PredSet}) {
>>> + assert((isa<SCEVCouldNotCompute>(MaxNotTaken) ||
>>> + isa<SCEVConstant>(MaxNotTaken)) &&
>>> + "No point in having a non-constant max backedge taken count!");
>>> +}
>>>
>>> ScalarEvolution::ExitLimit::ExitLimit(const SCEV *E, const SCEV *M,
>>> bool MaxOrZero)
>>> - : ExitLimit(E, M, MaxOrZero, None) {}
>>> + : ExitLimit(E, M, MaxOrZero, None) {
>>> + assert((isa<SCEVCouldNotCompute>(MaxNotTaken) ||
>>> + isa<SCEVConstant>(MaxNotTaken)) &&
>>> + "No point in having a non-constant max backedge taken count!");
>>> +}
>>>
>>> /// Allocate memory for BackedgeTakenInfo and copy the not-taken count of
>>> each
>>> /// computable exit into a persistent ExitNotTakenInfo array.
>>> @@ -6018,6 +6035,8 @@ ScalarEvolution::BackedgeTakenInfo::Back
>>>
>>> return ExitNotTakenInfo(ExitBB, EL.ExactNotTaken,
>>> std::move(Predicate));
>>> });
>>> + assert((isa<SCEVCouldNotCompute>(MaxCount) ||
>>> isa<SCEVConstant>(MaxCount)) &&
>>> + "No point in having a non-constant max backedge taken count!");
>>> }
>>>
>>> /// Invalidate this result and free the ExitNotTakenInfo array.
>>> @@ -6279,7 +6298,7 @@ ScalarEvolution::ExitLimit ScalarEvoluti
>>> // to not.
>>> if (isa<SCEVCouldNotCompute>(MaxBECount) &&
>>> !isa<SCEVCouldNotCompute>(BECount))
>>> - MaxBECount = BECount;
>>> + MaxBECount =
>>> getConstant(getUnsignedRange(BECount).getUnsignedMax());
>>>
>>> return ExitLimit(BECount, MaxBECount, false,
>>> {&EL0.Predicates, &EL1.Predicates});
>>> @@ -7583,13 +7602,20 @@ ScalarEvolution::howFarToZero(const SCEV
>>> loopHasNoAbnormalExits(AddRec->getLoop())) {
>>> const SCEV *Exact =
>>> getUDivExpr(Distance, CountDown ? getNegativeSCEV(Step) : Step);
>>> - return ExitLimit(Exact, Exact, false, Predicates);
>>> + const SCEV *Max =
>>> + Exact == getCouldNotCompute()
>>> + ? Exact
>>> + : getConstant(getUnsignedRange(Exact).getUnsignedMax());
>>> + return ExitLimit(Exact, Max, false, Predicates);
>>> }
>>>
>>> // Solve the general equation.
>>> - const SCEV *E = SolveLinEquationWithOverflow(
>>> - StepC->getAPInt(), getNegativeSCEV(Start), *this);
>>> - return ExitLimit(E, E, false, Predicates);
>>> + const SCEV *E = SolveLinEquationWithOverflow(StepC->getAPInt(),
>>> + getNegativeSCEV(Start),
>>> *this);
>>> + const SCEV *M = E == getCouldNotCompute()
>>> + ? E
>>> + :
>>> getConstant(getUnsignedRange(E).getUnsignedMax());
>>> + return ExitLimit(E, M, false, Predicates);
>>> }
>>>
>>> ScalarEvolution::ExitLimit
>>> @@ -9218,8 +9244,9 @@ ScalarEvolution::howManyLessThans(const
>>> getConstant(StrideForMaxBECount), false);
>>> }
>>>
>>> - if (isa<SCEVCouldNotCompute>(MaxBECount))
>>> - MaxBECount = BECount;
>>> + if (isa<SCEVCouldNotCompute>(MaxBECount) &&
>>> + !isa<SCEVCouldNotCompute>(BECount))
>>> + MaxBECount = getConstant(getUnsignedRange(BECount).getUnsignedMax());
>>>
>>> return ExitLimit(BECount, MaxBECount, MaxOrZero, Predicates);
>>> }
>>>
>>> Modified: llvm/trunk/test/Analysis/ScalarEvolution/nsw.ll
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/ScalarEvolution/nsw.ll?rev=303497&r1=303496&r2=303497&view=diff
>>>
>>> ==============================================================================
>>> --- llvm/trunk/test/Analysis/ScalarEvolution/nsw.ll (original)
>>> +++ llvm/trunk/test/Analysis/ScalarEvolution/nsw.ll Sat May 20 20:47:50
>>> 2017
>>> @@ -102,7 +102,7 @@ for.body.i.i:
>>> %cmp.i.i = icmp eq i32* %ptrincdec.i.i, %end
>>> br i1 %cmp.i.i, label %_ZSt4fillIPiiEvT_S1_RKT0_.exit, label
>>> %for.body.i.i
>>> ; CHECK: Loop %for.body.i.i: backedge-taken count is ((-4 + (-1 * %begin)
>>> + %end) /u 4)
>>> -; CHECK: Loop %for.body.i.i: max backedge-taken count is ((-4 + (-1 *
>>> %begin) + %end) /u 4)
>>> +; CHECK: Loop %for.body.i.i: max backedge-taken count is
>>> 4611686018427387903
>>> _ZSt4fillIPiiEvT_S1_RKT0_.exit: ; preds =
>>> %for.body.i.i, %entry
>>> ret void
>>> }
>>>
>>> Modified: llvm/trunk/test/Analysis/ScalarEvolution/trip-count-pow2.ll
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/ScalarEvolution/trip-count-pow2.ll?rev=303497&r1=303496&r2=303497&view=diff
>>>
>>> ==============================================================================
>>> --- llvm/trunk/test/Analysis/ScalarEvolution/trip-count-pow2.ll (original)
>>> +++ llvm/trunk/test/Analysis/ScalarEvolution/trip-count-pow2.ll Sat May 20
>>> 20:47:50 2017
>>> @@ -14,7 +14,7 @@ exit:
>>>
>>> ; CHECK-LABEL: @test1
>>> ; CHECK: Loop %loop: backedge-taken count is ((-32 + (96 * %n)) /u 32)
>>> -; CHECK: Loop %loop: max backedge-taken count is ((-32 + (96 * %n)) /u
>>> 32)
>>> +; CHECK: Loop %loop: max backedge-taken count is 134217727
>>> }
>>>
>>> ; PR19183
>>> @@ -32,7 +32,7 @@ exit:
>>>
>>> ; CHECK-LABEL: @test2
>>> ; CHECK: Loop %loop: backedge-taken count is ((-32 + (32 * (%n /u 32)))
>>> /u 32)
>>> -; CHECK: Loop %loop: max backedge-taken count is ((-32 + (32 * (%n /u
>>> 32))) /u 32)
>>> +; CHECK: Loop %loop: max backedge-taken count is 134217727
>>> }
>>>
>>> define void @test3(i32 %n) {
>>> @@ -49,7 +49,7 @@ exit:
>>>
>>> ; CHECK-LABEL: @test3
>>> ; CHECK: Loop %loop: backedge-taken count is ((-32 + (32 * %n)) /u 32)
>>> -; CHECK: Loop %loop: max backedge-taken count is ((-32 + (32 * %n)) /u
>>> 32)
>>> +; CHECK: Loop %loop: max backedge-taken count is 134217727
>>> }
>>>
>>> define void @test4(i32 %n) {
>>> @@ -66,7 +66,7 @@ exit:
>>>
>>> ; CHECK-LABEL: @test4
>>> ; CHECK: Loop %loop: backedge-taken count is ((-4 + (-1431655764 * %n))
>>> /u 4)
>>> -; CHECK: Loop %loop: max backedge-taken count is ((-4 + (-1431655764 *
>>> %n)) /u 4)
>>> +; CHECK: Loop %loop: max backedge-taken count is 1073741823
>>> }
>>>
>>> define void @test5(i32 %n) {
>>> @@ -83,5 +83,5 @@ exit:
>>>
>>> ; CHECK-LABEL: @test5
>>> ; CHECK: Loop %loop: backedge-taken count is ((-4 + (4 * %n)) /u 4)
>>> -; CHECK: Loop %loop: max backedge-taken count is ((-4 + (4 * %n)) /u 4)
>>> +; CHECK: Loop %loop: max backedge-taken count is 1073741823
>>> }
>>>
>>>
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