[llvm] r243057 - fix crash in machine trace metrics due to processing dbg_value instructions (PR24199)

Wed Jul 29 10:16:37 PDT 2015

Ping?

On Mon, Jul 27, 2015 at 1:25 PM, Hans Wennborg <hans at chromium.org> wrote:
> Ping?
>
> On Fri, Jul 24, 2015 at 9:28 AM, Hans Wennborg <hans at chromium.org> wrote:
>> Seems reasonable.
>>
>> Evan, I believe you're the code owner here. OK to merge to 3.7?
>>
>> On Fri, Jul 24, 2015 at 8:57 AM, Robinson, Paul
>> <Paul_Robinson at playstation.sony.com> wrote:
>>> Can we please have this merged to the 3.7 branch?
>>> Thanks,
>>> --paulr
>>>
>>>> -----Original Message-----
>>>> From: llvm-commits-bounces at cs.uiuc.edu [mailto:llvm-commits-
>>>> bounces at cs.uiuc.edu] On Behalf Of Sanjay Patel
>>>> Sent: Thursday, July 23, 2015 3:57 PM
>>>> To: llvm-commits at cs.uiuc.edu
>>>> Subject: [llvm] r243057 - fix crash in machine trace metrics due to
>>>> processing dbg_value instructions (PR24199)
>>>>
>>>> Author: spatel
>>>> Date: Thu Jul 23 17:56:53 2015
>>>> New Revision: 243057
>>>>
>>>> URL: http://llvm.org/viewvc/llvm-project?rev=243057&view=rev
>>>> Log:
>>>> fix crash in machine trace metrics due to processing dbg_value
>>>> instructions (PR24199)
>>>>
>>>> The test in PR24199 ( https://llvm.org/bugs/show_bug.cgi?id=24199 )
>>>> crashes because machine
>>>> trace metrics was not ignoring dbg_value instructions when calculating
>>>> data dependencies.
>>>>
>>>> The machine-combiner pass asks machine trace metrics to calculate an
>>>> instruction trace,
>>>> does some reassociations, and calls
>>>> MachineInstr::eraseFromParentAndMarkDBGValuesForRemoval()
>>>> along with MachineTraceMetrics::invalidate(). The dbg_value instructions
>>>> have their operands
>>>> invalidated, but the instructions are not expected to be deleted.
>>>>
>>>> On a subsequent loop iteration of the machine-combiner pass, machine trace
>>>> metrics would be
>>>> called again and die while accessing the invalid debug instructions.
>>>>
>>>> Differential Revision: http://reviews.llvm.org/D11423
>>>>
>>>>
>>>> Added:
>>>>     llvm/trunk/test/CodeGen/X86/machine-trace-metrics-crash.ll
>>>> Modified:
>>>>     llvm/trunk/lib/CodeGen/MachineTraceMetrics.cpp
>>>>
>>>> Modified: llvm/trunk/lib/CodeGen/MachineTraceMetrics.cpp
>>>> URL: http://llvm.org/viewvc/llvm-
>>>> project/llvm/trunk/lib/CodeGen/MachineTraceMetrics.cpp?rev=243057&r1=24305
>>>> 6&r2=243057&view=diff
>>>> ==========================================================================
>>>> ====
>>>> --- llvm/trunk/lib/CodeGen/MachineTraceMetrics.cpp (original)
>>>> +++ llvm/trunk/lib/CodeGen/MachineTraceMetrics.cpp Thu Jul 23 17:56:53
>>>> 2015
>>>> @@ -624,6 +624,10 @@ struct DataDep {
>>>>  static bool getDataDeps(const MachineInstr *UseMI,
>>>>                          SmallVectorImpl<DataDep> &Deps,
>>>>                          const MachineRegisterInfo *MRI) {
>>>> +  // Debug values should not be included in any calculations.
>>>> +  if (UseMI->isDebugValue())
>>>> +    return false;
>>>> +
>>>>    bool HasPhysRegs = false;
>>>>    for (MachineInstr::const_mop_iterator I = UseMI->operands_begin(),
>>>>         E = UseMI->operands_end(); I != E; ++I) {
>>>>
>>>> Added: llvm/trunk/test/CodeGen/X86/machine-trace-metrics-crash.ll
>>>> URL: http://llvm.org/viewvc/llvm-
>>>> project/llvm/trunk/test/CodeGen/X86/machine-trace-metrics-
>>>> crash.ll?rev=243057&view=auto
>>>> ==========================================================================
>>>> ====
>>>> --- llvm/trunk/test/CodeGen/X86/machine-trace-metrics-crash.ll (added)
>>>> +++ llvm/trunk/test/CodeGen/X86/machine-trace-metrics-crash.ll Thu Jul 23
>>>> 17:56:53 2015
>>>> @@ -0,0 +1,62 @@
>>>> +; RUN: llc -mtriple=x86_64-unknown-unknown -mcpu=x86-64 -mattr=sse -
>>>> enable-unsafe-fp-math < %s | FileCheck %s
>>>> +
>>>> +; The debug info in this test case was causing a crash because machine
>>>> trace metrics
>>>> +; did not correctly ignore debug instructions. The check lines ensure
>>>> that the
>>>> +; machine-combiner pass has run, reassociated the add operands, and
>>>> therefore
>>>> +; used machine trace metrics.
>>>> +
>>>> +define void @PR24199() {
>>>> +; CHECK-LABEL:       PR24199:
>>>> +; CHECK:     addss   %xmm1, %xmm0
>>>> +; CHECK:     addss   %xmm2, %xmm0
>>>> +
>>>> +entry:
>>>> +  %i = alloca %struct.A, align 8
>>>> +  %tobool = icmp ne i32 undef, 0
>>>> +  br i1 undef, label %if.end, label %if.then
>>>> +
>>>> +if.then:
>>>> +  br label %if.end
>>>> +
>>>> +if.end:
>>>> +  %h = phi float [ 0.0, %if.then ], [ 4.0, %entry ]
>>>> +  call void @foo(%struct.A* nonnull undef)
>>>> +  tail call void @llvm.dbg.value(metadata %struct.A* undef, i64 0,
>>>> metadata !5, metadata !4), !dbg !6
>>>> +  tail call void @llvm.dbg.value(metadata float %h, i64 0, metadata !5,
>>>> metadata !4), !dbg !6
>>>> +  %n0 = load float, float* undef, align 4
>>>> +  %mul = fmul fast float %n0, %h
>>>> +  %add = fadd fast float %mul, 1.0
>>>> +  tail call void @llvm.dbg.value(metadata %struct.A* undef, i64 0,
>>>> metadata !5, metadata !4), !dbg !6
>>>> +  tail call void @llvm.dbg.value(metadata float %add, i64 0, metadata !5,
>>>> metadata !4), !dbg !6
>>>> +  %add.i = fadd fast float %add, %n0
>>>> +  store float %add.i, float* undef, align 4
>>>> +  %n1 = bitcast %struct.A* %i to i8*
>>>> +  call void @llvm.lifetime.start(i64 16, i8* %n1)
>>>> +  %n2 = load <2 x float>, <2 x float>* undef, align 8
>>>> +  %conv = uitofp i1 %tobool to float
>>>> +  %bitcast = extractelement <2 x float> %n2, i32 0
>>>> +  %factor = fmul fast float %bitcast, 2.0
>>>> +  %add3 = fadd fast float %factor, %conv
>>>> +  call void @bar(float %add3)
>>>> +  ret void
>>>> +}
>>>> +
>>>> +%struct.A = type { float, float }
>>>> +
>>>> +declare void @bar(float)
>>>> +declare void @foo(%struct.A*)
>>>> +declare void @llvm.lifetime.start(i64, i8* nocapture)
>>>> +declare void @llvm.dbg.value(metadata, i64, metadata, metadata)
>>>> +
>>>> +!llvm.dbg.cu = !{!0}
>>>> +!llvm.module.flags = !{!2}
>>>> +
>>>> +!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1,
>>>> isOptimized: true, runtimeVersion: 0, emissionKind: 1)
>>>> +!1 = !DIFile(filename: "24199.cpp", directory: "/bin")
>>>> +!2 = !{i32 2, !"Debug Info Version", i32 3}
>>>> +!3 = !DISubprogram(linkageName: "foo", file: !1, line: 18, isLocal:
>>>> false, isDefinition: true, scopeLine: 18, function: void (%struct.A*)*
>>>> @foo)
>>>> +!4 = !DIExpression()
>>>> +!5 = !DILocalVariable(tag: DW_TAG_arg_variable, name: "this", arg: 1,
>>>> scope: !3, flags: DIFlagArtificial | DIFlagObjectPointer)
>>>> +!6 = !DILocation(line: 0, scope: !3)
>>>> +
>>>> +
>>>>
>>>>
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