[llvm] r348988 - [LoopDeletion] Update debug values after loop deletion.
Davide Italiano via llvm-commits
llvm-commits at lists.llvm.org
Thu Dec 13 10:11:19 PST 2018
Interesting, taking a look at this now.
On Thu, Dec 13, 2018 at 4:36 AM Mikael Holmén
<mikael.holmen at ericsson.com> wrote:
>
> Hi Davide,
>
> I found a case that starts crashing with this commit.
>
> opt -o /dev/null reduced.ll -loop-deletion
>
> gives me
>
> build-all/bin/opt -o /dev/null reduced.ll -loop-deletion
> opt: ../lib/Bitcode/Writer/ValueEnumerator.cpp:807: void
> llvm::ValueEnumerator::EnumerateValue(const llvm::Value *): Assertion
> `!V->getType()->isVoidTy() && "Can't insert void values!"' failed.
> Stack dump:
> 0. Program arguments: build-all/bin/opt -o /dev/null reduced.ll
> -loop-deletion
> 1. Running pass 'Bitcode Writer' on module 'reduced.ll'.
> #0 0x0000000002241dc4 PrintStackTraceSignalHandler(void*)
> (build-all/bin/opt+0x2241dc4)
> #1 0x000000000223fef0 llvm::sys::RunSignalHandlers()
> (build-all/bin/opt+0x223fef0)
> #2 0x0000000002242128 SignalHandler(int) (build-all/bin/opt+0x2242128)
> #3 0x00007fe9a6e38330 __restore_rt
> (/lib/x86_64-linux-gnu/libpthread.so.0+0x10330)
> #4 0x00007fe9a5a27c37 gsignal
> /build/eglibc-ripdx6/eglibc-2.19/signal/../nptl/sysdeps/unix/sysv/linux/raise.c:56:0
> #5 0x00007fe9a5a2b028 abort
> /build/eglibc-ripdx6/eglibc-2.19/stdlib/abort.c:91:0
> #6 0x00007fe9a5a20bf6 __assert_fail_base
> /build/eglibc-ripdx6/eglibc-2.19/assert/assert.c:92:0
> #7 0x00007fe9a5a20ca2 (/lib/x86_64-linux-gnu/libc.so.6+0x2fca2)
> #8 0x0000000001815b4d llvm::ValueEnumerator::EnumerateValue(llvm::Value
> const*) (build-all/bin/opt+0x1815b4d)
> #9 0x0000000001819222
> llvm::ValueEnumerator::enumerateMetadataImpl(unsigned int,
> llvm::Metadata const*) (build-all/bin/opt+0x1819222)
> #10 0x000000000181850c llvm::ValueEnumerator::EnumerateMetadata(unsigned
> int, llvm::Metadata const*) (build-all/bin/opt+0x181850c)
> #11 0x0000000001815304
> llvm::ValueEnumerator::ValueEnumerator(llvm::Module const&, bool)
> (build-all/bin/opt+0x1815304)
> #12 0x00000000017ed44c (anonymous
> namespace)::ModuleBitcodeWriterBase::ModuleBitcodeWriterBase(llvm::Module
> const&, llvm::StringTableBuilder&, llvm::BitstreamWriter&, bool,
> llvm::ModuleSummaryIndex const*) (build-all/bin/opt+0x17ed44c)
> #13 0x00000000017de788 llvm::BitcodeWriter::writeModule(llvm::Module
> const&, bool, llvm::ModuleSummaryIndex const*, bool, std::array<unsigned
> int, 5ul>*) (build-all/bin/opt+0x17de788)
> #14 0x00000000017e651a llvm::WriteBitcodeToFile(llvm::Module const&,
> llvm::raw_ostream&, bool, llvm::ModuleSummaryIndex const*, bool,
> std::array<unsigned int, 5ul>*) (build-all/bin/opt+0x17e651a)
> #15 0x00000000017dd5ee (anonymous
> namespace)::WriteBitcodePass::runOnModule(llvm::Module&)
> (build-all/bin/opt+0x17dd5ee)
> #16 0x0000000001c54cea llvm::legacy::PassManagerImpl::run(llvm::Module&)
> (build-all/bin/opt+0x1c54cea)
> #17 0x0000000000786b8b main (build-all/bin/opt+0x786b8b)
> #18 0x00007fe9a5a12f45 __libc_start_main
> /build/eglibc-ripdx6/eglibc-2.19/csu/libc-start.c:321:0
> #19 0x000000000076c14d _start (build-all/bin/opt+0x76c14d)
> Abort
>
> I found this on my out-of-tree target and then I've reduced it and it
> still exposes the original crash I got, but possibly I've messed with
> the metadata so it looks weird now.
>
> It still crashes with this patch and not before it though.
>
> Regards,
> Mikael
>
> On 12/13/18 12:32 AM, Davide Italiano via llvm-commits wrote:
> > Author: davide
> > Date: Wed Dec 12 15:32:35 2018
> > New Revision: 348988
> >
> > URL: http://llvm.org/viewvc/llvm-project?rev=348988&view=rev
> > Log:
> > [LoopDeletion] Update debug values after loop deletion.
> >
> > When loops are deleted, we don't keep track of variables modified inside
> > the loops, so the DI will contain the wrong value for these.
> >
> > e.g.
> >
> > int b() {
> >
> > int i;
> > for (i = 0; i < 2; i++)
> > ;
> > patatino();
> > return a;
> > -> 6 patatino();
> >
> > 7 return a;
> > 8 }
> > 9 int main() { b(); }
> > (lldb) frame var i
> > (int) i = 0
> >
> > We mark instead these values as unavailable inserting a
> > @llvm.dbg.value(undef to make sure we don't end up printing an incorrect
> > value in the debugger. We could consider doing something fancier,
> > for, e.g. constants, in the future.
> >
> > PR39868.
> > rdar://problem/46418795)
> >
> > Differential Revision: https://reviews.llvm.org/D55299
> >
> > Added:
> > llvm/trunk/test/Transforms/LoopDeletion/diundef.ll
> > Modified:
> > llvm/trunk/lib/Transforms/Utils/LoopUtils.cpp
> >
> > Modified: llvm/trunk/lib/Transforms/Utils/LoopUtils.cpp
> > URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/LoopUtils.cpp?rev=348988&r1=348987&r2=348988&view=diff
> > ==============================================================================
> > --- llvm/trunk/lib/Transforms/Utils/LoopUtils.cpp (original)
> > +++ llvm/trunk/lib/Transforms/Utils/LoopUtils.cpp Wed Dec 12 15:32:35 2018
> > @@ -26,9 +26,11 @@
> > #include "llvm/Analysis/ScalarEvolutionExpressions.h"
> > #include "llvm/Analysis/TargetTransformInfo.h"
> > #include "llvm/Analysis/ValueTracking.h"
> > +#include "llvm/IR/DIBuilder.h"
> > #include "llvm/IR/DomTreeUpdater.h"
> > #include "llvm/IR/Dominators.h"
> > #include "llvm/IR/Instructions.h"
> > +#include "llvm/IR/IntrinsicInst.h"
> > #include "llvm/IR/Module.h"
> > #include "llvm/IR/PatternMatch.h"
> > #include "llvm/IR/ValueHandle.h"
> > @@ -567,6 +569,12 @@ void llvm::deleteDeadLoop(Loop *L, Domin
> > DTU.deleteEdge(Preheader, L->getHeader());
> > }
> >
> > + // Use a map to unique and a vector to guarantee deterministic ordering.
> > + llvm::SmallDenseMap<std::pair<DIVariable *, DIExpression *>,
> > + DbgVariableIntrinsic *, 4>
> > + DeadDebugMap;
> > + llvm::SmallVector<DbgVariableIntrinsic *, 4> DeadDebugInst;
> > +
> > // Given LCSSA form is satisfied, we should not have users of instructions
> > // within the dead loop outside of the loop. However, LCSSA doesn't take
> > // unreachable uses into account. We handle them here.
> > @@ -591,8 +599,27 @@ void llvm::deleteDeadLoop(Loop *L, Domin
> > "Unexpected user in reachable block");
> > U.set(Undef);
> > }
> > + auto *DVI = dyn_cast<DbgVariableIntrinsic>(&I);
> > + if (!DVI)
> > + continue;
> > + auto Key = DeadDebugMap.find({DVI->getVariable(), DVI->getExpression()});
> > + if (Key != DeadDebugMap.end())
> > + continue;
> > + DeadDebugMap[{DVI->getVariable(), DVI->getExpression()}] = DVI;
> > + DeadDebugInst.push_back(DVI);
> > }
> >
> > + // After the loop has been deleted all the values defined and modified
> > + // inside the loop are going to be unavailable.
> > + // Since debug values in the loop have been deleted, inserting an undef
> > + // dbg.value truncates the range of any dbg.value before the loop where the
> > + // loop used to be. This is particularly important for constant values.
> > + DIBuilder DIB(*ExitBlock->getModule());
> > + for (auto *DVI : DeadDebugInst)
> > + DIB.insertDbgValueIntrinsic(
> > + UndefValue::get(DVI->getType()), DVI->getVariable(),
> > + DVI->getExpression(), DVI->getDebugLoc(), ExitBlock->getFirstNonPHI());
> > +
> > // Remove the block from the reference counting scheme, so that we can
> > // delete it freely later.
> > for (auto *Block : L->blocks())
> >
> > Added: llvm/trunk/test/Transforms/LoopDeletion/diundef.ll
> > URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopDeletion/diundef.ll?rev=348988&view=auto
> > ==============================================================================
> > --- llvm/trunk/test/Transforms/LoopDeletion/diundef.ll (added)
> > +++ llvm/trunk/test/Transforms/LoopDeletion/diundef.ll Wed Dec 12 15:32:35 2018
> > @@ -0,0 +1,75 @@
> > +; RUN: opt %s -loop-deletion -S | FileCheck %s
> > +
> > +target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
> > +target triple = "x86_64-apple-macosx10.14.0"
> > +
> > + at a = common local_unnamed_addr global i32 0, align 4, !dbg !0
> > +
> > +define i32 @b() local_unnamed_addr !dbg !12 {
> > +entry:
> > + call void @llvm.dbg.value(metadata i32 0, metadata !16, metadata !DIExpression()), !dbg !17
> > + br label %for.cond, !dbg !18
> > +
> > +for.cond: ; preds = %for.cond, %entry
> > + %i.0 = phi i32 [ 0, %entry ], [ %inc, %for.cond ], !dbg !20
> > + call void @llvm.dbg.value(metadata i32 %i.0, metadata !16, metadata !DIExpression()), !dbg !17
> > + %inc = add nuw nsw i32 %i.0, 1, !dbg !21
> > + call void @llvm.dbg.value(metadata i32 %inc, metadata !16, metadata !DIExpression()), !dbg !17
> > + %exitcond = icmp ne i32 %inc, 3, !dbg !23
> > + br i1 %exitcond, label %for.cond, label %for.end, !dbg !24, !llvm.loop !25
> > +
> > +; CHECK: call void @llvm.dbg.value(metadata void undef, metadata !16, metadata !DIExpression()), !dbg !17
> > +; CHECK-NEXT: %call = tail call i32 {{.*}} @patatino()
> > +for.end: ; preds = %for.cond
> > + %call = tail call i32 (...) @patatino() #3, !dbg !27
> > + %0 = load i32, i32* @a, align 4, !dbg !28
> > + ret i32 %0, !dbg !33
> > +}
> > +
> > +declare i32 @patatino(...) local_unnamed_addr
> > +
> > +define i32 @main() local_unnamed_addr !dbg !34 {
> > +entry:
> > + %call = call i32 @b(), !dbg !35
> > + ret i32 0, !dbg !36
> > +}
> > +
> > +declare void @llvm.dbg.value(metadata, metadata, metadata)
> > +
> > +!llvm.dbg.cu = !{!2}
> > +!llvm.module.flags = !{!7, !8, !9, !10}
> > +!llvm.ident = !{!11}
> > +
> > +!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
> > +!1 = distinct !DIGlobalVariable(name: "a", scope: !2, file: !3, line: 1, type: !6, isLocal: false, isDefinition: true)
> > +!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 8.0.0 ", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5, nameTableKind: GNU)
> > +!3 = !DIFile(filename: "a.c", directory: "/Users/davide/work/llvm-project-20170507/build-debug/bin")
> > +!4 = !{}
> > +!5 = !{!0}
> > +!6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
> > +!7 = !{i32 2, !"Dwarf Version", i32 4}
> > +!8 = !{i32 2, !"Debug Info Version", i32 3}
> > +!9 = !{i32 1, !"wchar_size", i32 4}
> > +!10 = !{i32 7, !"PIC Level", i32 2}
> > +!11 = !{!"clang version 8.0.0 "}
> > +!12 = distinct !DISubprogram(name: "b", scope: !3, file: !3, line: 2, type: !13, scopeLine: 2, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !15)
> > +!13 = !DISubroutineType(types: !14)
> > +!14 = !{!6}
> > +!15 = !{!16}
> > +!16 = !DILocalVariable(name: "i", scope: !12, file: !3, line: 3, type: !6)
> > +!17 = !DILocation(line: 3, column: 7, scope: !12)
> > +!18 = !DILocation(line: 4, column: 8, scope: !19)
> > +!19 = distinct !DILexicalBlock(scope: !12, file: !3, line: 4, column: 3)
> > +!20 = !DILocation(line: 0, scope: !19)
> > +!21 = !DILocation(line: 4, column: 23, scope: !22)
> > +!22 = distinct !DILexicalBlock(scope: !19, file: !3, line: 4, column: 3)
> > +!23 = !DILocation(line: 4, column: 17, scope: !22)
> > +!24 = !DILocation(line: 4, column: 3, scope: !19)
> > +!25 = distinct !{!25, !24, !26}
> > +!26 = !DILocation(line: 5, column: 5, scope: !19)
> > +!27 = !DILocation(line: 6, column: 3, scope: !12)
> > +!28 = !DILocation(line: 7, column: 10, scope: !12)
> > +!33 = !DILocation(line: 7, column: 3, scope: !12)
> > +!34 = distinct !DISubprogram(name: "main", scope: !3, file: !3, line: 9, type: !13, scopeLine: 9, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !4)
> > +!35 = !DILocation(line: 9, column: 14, scope: !34)
> > +!36 = !DILocation(line: 9, column: 19, scope: !34)
> >
> >
> > _______________________________________________
> > llvm-commits mailing list
> > llvm-commits at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
> >
--
Davide
"There are no solved problems; there are only problems that are more
or less solved" -- Henri Poincare
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