[llvm] r336419 - CallGraphSCCPass: iterate over all functions.
Evgenii Stepanov via llvm-commits
llvm-commits at lists.llvm.org
Fri Jul 13 08:23:59 PDT 2018
MSan buildbot crashes are still happening, once per 8 builds or so. I can't
reproduce them locally and am not 100% sure that this is the change, but,
given the nondeterminism detected on the other bot, I'm going to
tentatively revert it.
On Thu, Jul 12, 2018 at 12:01 PM, Galina Kistanova <gkistanova at gmail.com>
wrote:
> Hello Tim,
>
> This commit has introduced nondeterminism. Please see
> http://lab.llvm.org:8011/builders/clang-with-thin-lto-ubuntu or
> http://lab.llvm.org:8011/builders/clang-with-lto-ubuntu build bots.
>
> This is in addition to those other problems mentioned already, or maybe
> some of the other problems are exposed because of this.
>
> Since the problem is around for quite long now, maybe it worth reverting
> till you will figure out what's wrong and how to fix it?
>
> Thanks
>
> Galina
>
>
>
>
> On Tue, Jul 10, 2018 at 1:33 PM, Evgenii Stepanov via llvm-commits <
> llvm-commits at lists.llvm.org> wrote:
>
>> Hi Tim,
>>
>> MSan bootstrap bot has been randomly crashing lately with the following
>> trace:
>>
>> 3. Running pass 'CallGraph Pass Manager' on module
>> '/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm/lib/Tar
>> get/Hexagon/HexagonCommonGEP.cpp'.
>> #0 0x00005602f79f5cfa llvm::sys::PrintStackTrace(llvm::raw_ostream&)
>> (/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm_build0/
>> bin/clang-7+0x24f5cfa)
>> #1 0x00005602f79f42c5 llvm::sys::RunSignalHandlers()
>> (/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm_build0/
>> bin/clang-7+0x24f42c5)
>> #2 0x00005602f79f43dc SignalHandler(int) (/b/sanitizer-x86_64-linux-boo
>> tstrap-msan/build/llvm_build0/bin/clang-7+0x24f43dc)
>> #3 0x00007f63daa840c0 __restore_rt (/lib/x86_64-linux-gnu/libpthr
>> ead.so.0+0x110c0)
>> #4 0x00005602f6edf38e llvm::scc_iterator<llvm::CallGraph*,
>> llvm::GraphTraits<llvm::CallGraph*> >::DFSVisitChildren()
>> (/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm_build0/
>> bin/clang-7+0x19df38e)
>> #5 0x00005602f6edf5aa llvm::scc_iterator<llvm::CallGraph*,
>> llvm::GraphTraits<llvm::CallGraph*> >::GetNextSCC()
>> (/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm_build0/
>> bin/clang-7+0x19df5aa)
>> #6 0x00005602f6ee05ed (anonymous namespace)::CGPassManager::runOnModule(llvm::Module&)
>> (/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm_build0/
>> bin/clang-7+0x19e05ed)
>> #7 0x00005602f74ca5fd llvm::legacy::PassManagerImpl::run(llvm::Module&)
>> (/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm_build0/
>> bin/clang-7+0x1fca5fd)
>> #8 0x00005602f7bde5c1 (anonymous namespace)::EmitAssemblyHelper
>> ::EmitAssembly(clang::BackendAction, std::unique_ptr<llvm::raw_pwrite_stream,
>> std::default_delete<llvm::raw_pwrite_stream> >)
>> (/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm_build0/
>> bin/clang-7+0x26de5c1)
>> #9 0x00005602f7bdfdf0 clang::EmitBackendOutput(clang::DiagnosticsEngine&,
>> clang::HeaderSearchOptions const&, clang::CodeGenOptions const&,
>> clang::TargetOptions const&, clang::LangOptions const&, llvm::DataLayout
>> const&, llvm::Module*, clang::BackendAction, std::unique_ptr<llvm::raw_pwrite_stream,
>> std::default_delete<llvm::raw_pwrite_stream> >)
>> (/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm_build0/
>> bin/clang-7+0x26dfdf0)
>> #10 0x00005602f836f264 clang::BackendConsumer::Handle
>> TranslationUnit(clang::ASTContext&) (/b/sanitizer-x86_64-linux-boo
>> tstrap-msan/build/llvm_build0/bin/clang-7+0x2e6f264)
>> #11 0x00005602f8b37fa9 clang::ParseAST(clang::Sema&, bool, bool)
>> (/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm_build0/
>> bin/clang-7+0x3637fa9)
>> #12 0x00005602f836e4d9 clang::CodeGenAction::ExecuteAction()
>> (/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm_build0/
>> bin/clang-7+0x2e6e4d9)
>> #13 0x00005602f800da7e clang::FrontendAction::Execute()
>> (/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm_build0/
>> bin/clang-7+0x2b0da7e)
>> #14 0x00005602f7fd9496 clang::CompilerInstance::Execu
>> teAction(clang::FrontendAction&) (/b/sanitizer-x86_64-linux-boo
>> tstrap-msan/build/llvm_build0/bin/clang-7+0x2ad9496)
>> #15 0x00005602f80ad511 clang::ExecuteCompilerInvocation(clang::CompilerInstance*)
>> (/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm_build0/
>> bin/clang-7+0x2bad511)
>> #16 0x00005602f614c080 cc1_main(llvm::ArrayRef<char const*>, char const*,
>> void*) (/b/sanitizer-x86_64-linux-bootstrap-msan/build/llvm_build0/
>> bin/clang-7+0xc4c080)
>> #17 0x00005602f60c1a22 main (/b/sanitizer-x86_64-linux-boo
>> tstrap-msan/build/llvm_build0/bin/clang-7+0xbc1a22)
>> #18 0x00007f63d98312e1 __libc_start_main (/lib/x86_64-linux-gnu/libc.so
>> .6+0x202e1)
>> #19 0x00005602f61480aa _start (/b/sanitizer-x86_64-linux-boo
>> tstrap-msan/build/llvm_build0/bin/clang-7+0xc480aa)
>> clang-7: error: unable to execute command: Segmentation fault
>>
>> The crash happens roughly in 1 out of 5-to-10 builds, see history here:
>> http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-
>> bootstrap-msan?numbuilds=300
>>
>> The earliest it happened was this build at r336432:
>> http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-
>> bootstrap-msan/builds/5763
>>
>> I suspect that this change could be the culprit. Could you take a look?
>>
>>
>> On Fri, Jul 6, 2018 at 1:04 AM, Tim Northover via llvm-commits <
>> llvm-commits at lists.llvm.org> wrote:
>>
>>> Author: tnorthover
>>> Date: Fri Jul 6 01:04:47 2018
>>> New Revision: 336419
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=336419&view=rev
>>> Log:
>>> CallGraphSCCPass: iterate over all functions.
>>>
>>> Previously we only iterated over functions reachable from the set of
>>> external functions in the module. But since some of the passes under
>>> this (notably the always-inliner and coroutine lowerer) are required for
>>> correctness, they need to run over everything.
>>>
>>> This just adds an extra layer of iteration over the CallGraph to keep
>>> track of which functions we've already visited and get the next batch of
>>> SCCs.
>>>
>>> Should fix PR38029.
>>>
>>> Modified:
>>> llvm/trunk/include/llvm/ADT/SCCIterator.h
>>> llvm/trunk/lib/Analysis/CallGraphSCCPass.cpp
>>> llvm/trunk/test/Transforms/Inline/always-inline.ll
>>>
>>> Modified: llvm/trunk/include/llvm/ADT/SCCIterator.h
>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/
>>> ADT/SCCIterator.h?rev=336419&r1=336418&r2=336419&view=diff
>>> ============================================================
>>> ==================
>>> --- llvm/trunk/include/llvm/ADT/SCCIterator.h (original)
>>> +++ llvm/trunk/include/llvm/ADT/SCCIterator.h Fri Jul 6 01:04:47 2018
>>> @@ -90,6 +90,7 @@ class scc_iterator : public iterator_fac
>>> /// Compute the next SCC using the DFS traversal.
>>> void GetNextSCC();
>>>
>>> +public:
>>> scc_iterator(NodeRef entryN) : visitNum(0) {
>>> DFSVisitOne(entryN);
>>> GetNextSCC();
>>> @@ -98,12 +99,6 @@ class scc_iterator : public iterator_fac
>>> /// End is when the DFS stack is empty.
>>> scc_iterator() = default;
>>>
>>> -public:
>>> - static scc_iterator begin(const GraphT &G) {
>>> - return scc_iterator(GT::getEntryNode(G));
>>> - }
>>> - static scc_iterator end(const GraphT &) { return scc_iterator(); }
>>> -
>>> /// Direct loop termination test which is more efficient than
>>> /// comparison with \c end().
>>> bool isAtEnd() const {
>>> @@ -222,16 +217,25 @@ bool scc_iterator<GraphT, GT>::hasLoop()
>>> return false;
>>> }
>>>
>>> -/// Construct the begin iterator for a deduced graph type T.
>>> +/// Construct the begin iterator for a deduced graph type T, starting
>>> from its
>>> +/// entry node.
>>> template <class T> scc_iterator<T> scc_begin(const T &G) {
>>> - return scc_iterator<T>::begin(G);
>>> + return scc_iterator<T>(GraphTraits<T>::getEntryNode(G));
>>> }
>>>
>>> -/// Construct the end iterator for a deduced graph type T.
>>> +/// Construct the begin iterator for a graph type T, starting from the
>>> specified
>>> +/// node.
>>> +template <class T, class U = GraphTraits<T>>
>>> +scc_iterator<T, U> scc_begin(typename U::NodeRef N) {
>>> + return scc_iterator<T>(N);
>>> +}
>>> +
>>> + /// Construct the end iterator for a deduced graph type T.
>>> template <class T> scc_iterator<T> scc_end(const T &G) {
>>> - return scc_iterator<T>::end(G);
>>> + return scc_iterator<T>();
>>> }
>>>
>>> +
>>> } // end namespace llvm
>>>
>>> #endif // LLVM_ADT_SCCITERATOR_H
>>>
>>> Modified: llvm/trunk/lib/Analysis/CallGraphSCCPass.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/
>>> CallGraphSCCPass.cpp?rev=336419&r1=336418&r2=336419&view=diff
>>> ============================================================
>>> ==================
>>> --- llvm/trunk/lib/Analysis/CallGraphSCCPass.cpp (original)
>>> +++ llvm/trunk/lib/Analysis/CallGraphSCCPass.cpp Fri Jul 6 01:04:47
>>> 2018
>>> @@ -17,6 +17,7 @@
>>>
>>> #include "llvm/Analysis/CallGraphSCCPass.h"
>>> #include "llvm/ADT/DenseMap.h"
>>> +#include "llvm/ADT/DenseSet.h"
>>> #include "llvm/ADT/SCCIterator.h"
>>> #include "llvm/ADT/Statistic.h"
>>> #include "llvm/Analysis/CallGraph.h"
>>> @@ -63,6 +64,10 @@ public:
>>> /// whether any of the passes modifies the module, and if so, return
>>> true.
>>> bool runOnModule(Module &M) override;
>>>
>>> + /// Execute all of the passes scheduled for execution on a given SCC.
>>> Return
>>> + /// true if any passes modify the module.
>>> + bool runOnSCC(CallGraphSCC &SCC, CallGraph &CG);
>>> +
>>> using ModulePass::doInitialization;
>>> using ModulePass::doFinalization;
>>>
>>> @@ -448,51 +453,78 @@ bool CGPassManager::RunAllPassesOnSCC(Ca
>>> bool CGPassManager::runOnModule(Module &M) {
>>> CallGraph &CG = getAnalysis<CallGraphWrapperPass>().getCallGraph();
>>> bool Changed = doInitialization(CG);
>>> -
>>> - // Walk the callgraph in bottom-up SCC order.
>>> - scc_iterator<CallGraph*> CGI = scc_begin(&CG);
>>>
>>> - CallGraphSCC CurSCC(CG, &CGI);
>>> - while (!CGI.isAtEnd()) {
>>> - // Copy the current SCC and increment past it so that the pass can
>>> hack
>>> - // on the SCC if it wants to without invalidating our iterator.
>>> - const std::vector<CallGraphNode *> &NodeVec = *CGI;
>>> - CurSCC.initialize(NodeVec);
>>> - ++CGI;
>>> -
>>> - // At the top level, we run all the passes in this pass manager on
>>> the
>>> - // functions in this SCC. However, we support iterative
>>> compilation in the
>>> - // case where a function pass devirtualizes a call to a function.
>>> For
>>> - // example, it is very common for a function pass (often GVN or
>>> instcombine)
>>> - // to eliminate the addressing that feeds into a call. With that
>>> improved
>>> - // information, we would like the call to be an inline candidate,
>>> infer
>>> - // mod-ref information etc.
>>> - //
>>> - // Because of this, we allow iteration up to a specified iteration
>>> count.
>>> - // This only happens in the case of a devirtualized call, so we
>>> only burn
>>> - // compile time in the case that we're making progress. We also
>>> have a hard
>>> - // iteration count limit in case there is crazy code.
>>> - unsigned Iteration = 0;
>>> - bool DevirtualizedCall = false;
>>> - do {
>>> - LLVM_DEBUG(if (Iteration) dbgs()
>>> - << " SCCPASSMGR: Re-visiting SCC, iteration #" <<
>>> Iteration
>>> - << '\n');
>>> - DevirtualizedCall = false;
>>> - Changed |= RunAllPassesOnSCC(CurSCC, CG, DevirtualizedCall);
>>> - } while (Iteration++ < MaxIterations && DevirtualizedCall);
>>> -
>>> - if (DevirtualizedCall)
>>> - LLVM_DEBUG(dbgs() << " CGSCCPASSMGR: Stopped iteration after "
>>> - << Iteration
>>> - << " times, due to -max-cg-scc-iterations\n");
>>> + DenseSet<const Function *> Visited;
>>>
>>> - MaxSCCIterations.updateMax(Iteration);
>>> + CallGraph::iterator INext;
>>> + for (auto I = CG.begin(), E = CG.end(); I != E;) {
>>> + // Walk the callgraph in bottom-up SCC order.
>>> + auto CGI = scc_begin<CallGraph *>(I->second.get());
>>> +
>>> + CallGraphSCC CurSCC(CG, &CGI);
>>> + while (!CGI.isAtEnd()) {
>>> + const std::vector<CallGraphNode *> &NodeVec = *CGI;
>>> +
>>> + // Record that we've seen this set of functions so we don't run
>>> the pass
>>> + // twice.
>>> + for (auto *Elt : NodeVec)
>>> + Visited.insert(Elt->getFunction());
>>> +
>>> + // Copy the current SCC and increment past it so that the pass
>>> can hack
>>> + // on the SCC if it wants to without invalidating our iterator.
>>> + CurSCC.initialize(NodeVec);
>>> + ++CGI;
>>> +
>>> + // If we've got all functions reachable from our chosen initial
>>> node,
>>> + // calculate the next node we need to search from now before
>>> parts of the
>>> + // graph are invalidated.
>>> + if (CGI.isAtEnd()) {
>>> + do
>>> + ++I;
>>> + while (I != E && Visited.count(I->first));
>>> + }
>>> +
>>> + Changed |= runOnSCC(CurSCC, CG);
>>> + }
>>> }
>>> +
>>> Changed |= doFinalization(CG);
>>> return Changed;
>>> }
>>>
>>> +bool CGPassManager::runOnSCC(CallGraphSCC &CurSCC, CallGraph &CG) {
>>> + bool Changed = false;
>>> +
>>> + // At the top level, we run all the passes in this pass manager on the
>>> + // functions in this SCC. However, we support iterative compilation
>>> in the
>>> + // case where a function pass devirtualizes a call to a function. For
>>> + // example, it is very common for a function pass (often GVN or
>>> instcombine)
>>> + // to eliminate the addressing that feeds into a call. With that
>>> improved
>>> + // information, we would like the call to be an inline candidate,
>>> infer
>>> + // mod-ref information etc.
>>> + //
>>> + // Because of this, we allow iteration up to a specified iteration
>>> count.
>>> + // This only happens in the case of a devirtualized call, so we only
>>> burn
>>> + // compile time in the case that we're making progress. We also have
>>> a hard
>>> + // iteration count limit in case there is crazy code.
>>> + unsigned Iteration = 0;
>>> + bool DevirtualizedCall = false;
>>> + do {
>>> + LLVM_DEBUG(if (Iteration) dbgs()
>>> + << " SCCPASSMGR: Re-visiting SCC, iteration #" <<
>>> Iteration
>>> + << '\n');
>>> + DevirtualizedCall = false;
>>> + Changed |= RunAllPassesOnSCC(CurSCC, CG, DevirtualizedCall);
>>> + } while (Iteration++ < MaxIterations && DevirtualizedCall);
>>> +
>>> + if (DevirtualizedCall)
>>> + LLVM_DEBUG(dbgs() << " CGSCCPASSMGR: Stopped iteration after " <<
>>> Iteration
>>> + << " times, due to -max-cg-scc-iterations\n");
>>> +
>>> + MaxSCCIterations.updateMax(Iteration);
>>> + return Changed;
>>> +}
>>> +
>>> /// Initialize CG
>>> bool CGPassManager::doInitialization(CallGraph &CG) {
>>> bool Changed = false;
>>>
>>> Modified: llvm/trunk/test/Transforms/Inline/always-inline.ll
>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transfor
>>> ms/Inline/always-inline.ll?rev=336419&r1=336418&r2=336419&view=diff
>>> ============================================================
>>> ==================
>>> --- llvm/trunk/test/Transforms/Inline/always-inline.ll (original)
>>> +++ llvm/trunk/test/Transforms/Inline/always-inline.ll Fri Jul 6
>>> 01:04:47 2018
>>> @@ -316,3 +316,10 @@ define void @outer14() {
>>> call void @inner14()
>>> ret void
>>> }
>>> +
>>> +define internal i32 @outer15() {
>>> +; CHECK-LABEL: @outer15
>>> +; CHECK: ret i32 1
>>> + %res = call i32 @inner1()
>>> + ret i32 %res
>>> +}
>>>
>>>
>>> _______________________________________________
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>>> llvm-commits at lists.llvm.org
>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>>>
>>
>>
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>
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