Commit 390ed68b authored by Hans Wennborg's avatar Hans Wennborg
Browse files

Merging r243057: 

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r243057 | spatel | 2015-07-23 15:56:53 -0700 (Thu, 23 Jul 2015) | 16 lines

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


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llvm-svn: 243662
parent 9f19c533

llvm/lib/CodeGen/MachineTraceMetrics.cpp

+4 −0
Original line number Diff line number Diff line
@@ -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) {

llvm/test/CodeGen/X86/machine-trace-metrics-crash.ll

0 → 100644
+62 −0
Original line number Diff line number Diff line 
; 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)