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

Fri Jul 24 09:28:44 PDT 2015

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)
>> +
>> +
>>
>>
>> _______________________________________________
>> llvm-commits mailing list
>> llvm-commits at cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits