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fix crash in machine trace metrics due to processing dbg_value instructions (PR24199)

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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

llvm-svn: 243057
This commit is contained in:
Sanjay Patel 2015-07-23 22:56:53 +00:00
parent 2ce9369a79
commit 393560b776
2 changed files with 66 additions and 0 deletions
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4
lib/CodeGen/MachineTraceMetrics.cpp
View File

@ -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) {

62
test/CodeGen/X86/machine-trace-metrics-crash.ll Normal file
View File

@ -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)