[PATCH] D71539: [SCEV] Look through trivial PHIs.

Tue Sep 28 13:08:50 PDT 2021

bmahjour added a comment.

https://github.com/llvm/llvm-project/commit/764d9aa97905f202385b4f25f8d234630b4feef3 is exposing an issue in DependenceAnalysis:

  > cat bugpoint-reduced-simplified.ll
  ; ModuleID = 'bugpoint-reduced-simplified.bc'
  target datalayout = "e-m:e-i64:64-n32:64-S128-v256:256:256-v512:512:512"
  target triple = "powerpc64le-unknown-linux-gnu"

  define dso_local void @hotspotKernel([512 x double]* %temp) local_unnamed_addr #0 {
  entry:
    br label %for.cond1.preheader

  for.cond1.preheader:                              ; preds = %for.body272, %entry
    br label %for.body6

  for.body6:                                        ; preds = %for.body6, %for.cond1.preheader
    %c.2594 = phi i32 [ 1, %for.cond1.preheader ], [ %add27, %for.body6 ]
    %add27 = add nuw nsw i32 %c.2594, 1
    br i1 undef, label %for.body6, label %for.end63

  for.end63:                                        ; preds = %for.body6
    %c.1.lcssa = phi i32 [ %add27, %for.body6 ]
    %sub96 = add nsw i32 %c.1.lcssa, -1
    %0 = zext i32 %sub96 to i64
    %arrayidx98 = getelementptr inbounds [512 x double], [512 x double]* %temp, i64 0, i64 %0
    %1 = load double, double* %arrayidx98, align 8
    br label %for.body272

  for.body272:                                      ; preds = %for.body272, %for.end63
    %r.1597 = phi i32 [ 1, %for.end63 ], [ %add277, %for.body272 ]
    %idxprom274 = zext i32 %r.1597 to i64
    %add277 = add nuw nsw i32 %r.1597, 1
    %arrayidx295 = getelementptr inbounds [512 x double], [512 x double]* %temp, i64 %idxprom274, i64 510
    %2 = load double, double* %arrayidx295, align 8
    br i1 undef, label %for.body272, label %for.cond1.preheader, !llvm.loop !1
  }

  attributes #0 = { "target-features"="+altivec,+bpermd,+crypto,+direct-move,+extdiv,+htm,+isa-v207-instructions,+power8-vector,+vsx,-isa-v30-instructions,-power9-vector,-privileged,-rop-protect,-spe" }

  !llvm.ident = !{!0}

  !0 = !{!"version 14.0.0"}
  !1 = distinct !{!1, !2}
  !2 = !{!"llvm.loop.mustprogress"}

  opt -passes='print<da>' -disable-output bugpoint-reduced-simplified.ll

  'Dependence Analysis' for function 'hotspotKernel':
  Src:  %1 = load double, double* %arrayidx98, align 8 --> Dst:  %1 = load double, double* %arrayidx98, align 8
    da analyze - consistent input [S]!
  Src:  %1 = load double, double* %arrayidx98, align 8 --> Dst:  %2 = load double, double* %arrayidx295, align 8
    da analyze - opt: /home/bmahjour/workspaces/_all/upstream-fork/llvm-project/llvm/lib/Analysis/DependenceAnalysis.cpp:2161: bool llvm::DependenceInfo::testSIV(const llvm::SCEV *, const llvm::SCEV *, unsigned $
  PLEASE submit a bug report to https://bugs.llvm.org/ and include the crash backtrace.
  Stack dump:
  0.      Program arguments: /home/bmahjour/workspaces/_all/upstream-fork/build/bin/opt -passes=print<da> -disable-output bugpoint-reduced-simplified.ll
   #0 0x0000000012c87154 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/home/bmahjour/workspaces/_all/upstream-fork/build/bin/opt+0x12c87154)
   #1 0x0000000012c87554 PrintStackTraceSignalHandler(void*) Signals.cpp:0:0
   #2 0x0000000012c842b8 llvm::sys::RunSignalHandlers() (/home/bmahjour/workspaces/_all/upstream-fork/build/bin/opt+0x12c842b8)
   #3 0x0000000012c8781c SignalHandler(int) Signals.cpp:0:0
   #4 0x00002000000604d8 (linux-vdso64.so.1+0x4d8)
   #5 0x00002000005fea0c __libc_signal_restore_set /build/glibc-dBVPtL/glibc-2.27/signal/../sysdeps/unix/sysv/linux/nptl-signals.h:80:0
   #6 0x00002000005fea0c raise /build/glibc-dBVPtL/glibc-2.27/signal/../sysdeps/unix/sysv/linux/raise.c:48:0
   #7 0x0000200000600c60 abort /build/glibc-dBVPtL/glibc-2.27/stdlib/abort.c:79:0
   #8 0x00002000005ebbb8 __assert_fail_base /build/glibc-dBVPtL/glibc-2.27/assert/assert.c:92:0
   #9 0x00002000005ebc64 __assert_fail /build/glibc-dBVPtL/glibc-2.27/assert/assert.c:101:0
  #10 0x0000000011847ba4 llvm::DependenceInfo::testSIV(llvm::SCEV const*, llvm::SCEV const*, unsigned int&, llvm::FullDependence&, llvm::DependenceInfo::Constraint&, llvm::SCEV const*&) const (/home/bmahjour/wor$
  #11 0x0000000011854070 llvm::DependenceInfo::depends(llvm::Instruction*, llvm::Instruction*, bool) (/home/bmahjour/workspaces/_all/upstream-fork/build/bin/opt+0x11854070)
  #12 0x0000000011833f9c dumpExampleDependence(llvm::raw_ostream&, llvm::DependenceInfo*) DependenceAnalysis.cpp:0:0
  #13 0x0000000011834594 llvm::DependenceAnalysisPrinterPass::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/home/bmahjour/workspaces/_all/upstream-fork/build/bin/opt+0x11834594)
  #14 0x0000000012fff0fc llvm::detail::PassModel<llvm::Function, llvm::DependenceAnalysisPrinterPass, llvm::PreservedAnalyses, llvm::AnalysisManager<llvm::Function> >::run(llvm::Function&, llvm::AnalysisManager<$
  #15 0x00000000122e4b6c llvm::PassManager<llvm::Function, llvm::AnalysisManager<llvm::Function> >::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/home/bmahjour/workspaces/_all/upstream-fork/buil$
  #16 0x000000001074aedc llvm::detail::PassModel<llvm::Function, llvm::PassManager<llvm::Function, llvm::AnalysisManager<llvm::Function> >, llvm::PreservedAnalyses, llvm::AnalysisManager<llvm::Function> >::run(l$
  #17 0x00000000122ea58c llvm::ModuleToFunctionPassAdaptor::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/home/bmahjour/workspaces/_all/upstream-fork/build/bin/opt+0x122ea58c)
  #18 0x000000001039e95c llvm::detail::PassModel<llvm::Module, llvm::ModuleToFunctionPassAdaptor, llvm::PreservedAnalyses, llvm::AnalysisManager<llvm::Module> >::run(llvm::Module&, llvm::AnalysisManager<llvm::Mo$
  #19 0x00000000122e3840 llvm::PassManager<llvm::Module, llvm::AnalysisManager<llvm::Module> >::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/home/bmahjour/workspaces/_all/upstream-fork/build/bin/op$
  #20 0x0000000010392d60 llvm::runPassPipeline(llvm::StringRef, llvm::Module&, llvm::TargetMachine*, llvm::TargetLibraryInfoImpl*, llvm::ToolOutputFile*, llvm::ToolOutputFile*, llvm::ToolOutputFile*, llvm::Strin$
  #21 0x00000000103ac0cc main (/home/bmahjour/workspaces/_all/upstream-fork/build/bin/opt+0x103ac0cc)
  #22 0x00002000005d449c generic_start_main /build/glibc-dBVPtL/glibc-2.27/csu/../csu/libc-start.c:310:0
  #23 0x00002000005d469c __libc_start_main /build/glibc-dBVPtL/glibc-2.27/csu/../sysdeps/unix/sysv/linux/powerpc/libc-start.c:116:0

Repository:
  rG LLVM Github Monorepo

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