[llvm] r245588 - Fix a debug location handling bug in GVN.
Adrian Prantl via llvm-commits
llvm-commits at lists.llvm.org
Thu Aug 20 11:42:20 PDT 2015
> On Aug 20, 2015, at 11:36 AM, David Blaikie <dblaikie at gmail.com> wrote:
>
>
>
> On Thu, Aug 20, 2015 at 11:28 AM, Adrian Prantl via llvm-commits <llvm-commits at lists.llvm.org <mailto:llvm-commits at lists.llvm.org>> wrote:
>
> > On Aug 20, 2015, at 11:23 AM, Adrian Prantl via llvm-commits <llvm-commits at lists.llvm.org <mailto:llvm-commits at lists.llvm.org>> wrote:
> >
> > Author: adrian
> > Date: Thu Aug 20 13:23:56 2015
> > New Revision: 245588
> >
> > URL: https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_viewvc_llvm-2Dproject-3Frev-3D245588-26view-3Drev&d=BQIGaQ&c=eEvniauFctOgLOKGJOplqw&r=cTx6f1tAfqPeajYunFWp7_8ot79RnHyNteqzig4fXmA&m=1OMFcIVXCQ-3a2cHjkzeoWw-2B9l6GXi6522rq-fXRo&s=UsPyOZjvOF75FKD4kBH1X1gMSZIq-pFRDC8kvWBS2w0&e= <https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_viewvc_llvm-2Dproject-3Frev-3D245588-26view-3Drev&d=BQIGaQ&c=eEvniauFctOgLOKGJOplqw&r=cTx6f1tAfqPeajYunFWp7_8ot79RnHyNteqzig4fXmA&m=1OMFcIVXCQ-3a2cHjkzeoWw-2B9l6GXi6522rq-fXRo&s=UsPyOZjvOF75FKD4kBH1X1gMSZIq-pFRDC8kvWBS2w0&e=>
> > Log:
> > Fix a debug location handling bug in GVN.
> > Caught by the famous "DebugLoc describes the currect SubProgram" assertion.
> >
> > When GVN is removing a nonlocal load it updates the debug location of the
> > SSA value it replaced the load with with the one of the load. In the
> > testcase this actually overwrites a valid debug location with an empty one.
> >
> > In reality GVN has to make an arbitrary choice between two equally valid
> > debug locations. This patch changes to behavior to only update the
> > location if the value doesn't already have a debug location.
> >
> > Added:
> > llvm/trunk/test/DebugInfo/gvn.ll
> > Modified:
> > llvm/trunk/lib/Transforms/Scalar/GVN.cpp
> >
> > Modified: llvm/trunk/lib/Transforms/Scalar/GVN.cpp
> > URL: https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_viewvc_llvm-2Dproject_llvm_trunk_lib_Transforms_Scalar_GVN.cpp-3Frev-3D245588-26r1-3D245587-26r2-3D245588-26view-3Ddiff&d=BQIGaQ&c=eEvniauFctOgLOKGJOplqw&r=cTx6f1tAfqPeajYunFWp7_8ot79RnHyNteqzig4fXmA&m=1OMFcIVXCQ-3a2cHjkzeoWw-2B9l6GXi6522rq-fXRo&s=qxyWSdB0E7E3fhM6zkYTzydfTcgVPfVFpm85bvbqaw0&e= <https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_viewvc_llvm-2Dproject_llvm_trunk_lib_Transforms_Scalar_GVN.cpp-3Frev-3D245588-26r1-3D245587-26r2-3D245588-26view-3Ddiff&d=BQIGaQ&c=eEvniauFctOgLOKGJOplqw&r=cTx6f1tAfqPeajYunFWp7_8ot79RnHyNteqzig4fXmA&m=1OMFcIVXCQ-3a2cHjkzeoWw-2B9l6GXi6522rq-fXRo&s=qxyWSdB0E7E3fhM6zkYTzydfTcgVPfVFpm85bvbqaw0&e=>
> > ==============================================================================
> > --- llvm/trunk/lib/Transforms/Scalar/GVN.cpp (original)
> > +++ llvm/trunk/lib/Transforms/Scalar/GVN.cpp Thu Aug 20 13:23:56 2015
> > @@ -1744,7 +1744,8 @@ bool GVN::processNonLocalLoad(LoadInst *
> > if (isa<PHINode>(V))
> > V->takeName(LI);
> > if (Instruction *I = dyn_cast<Instruction>(V))
> > - I->setDebugLoc(LI->getDebugLoc());
> > + if (LI->getDebugLoc())
> > + I->setDebugLoc(LI->getDebugLoc());
> > if (V->getType()->getScalarType()->isPointerTy())
> > MD->invalidateCachedPointerInfo(V);
> > markInstructionForDeletion(LI);
> >
> > Added: llvm/trunk/test/DebugInfo/gvn.ll
> > URL: https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_viewvc_llvm-2Dproject_llvm_trunk_test_DebugInfo_gvn.ll-3Frev-3D245588-26view-3Dauto&d=BQIGaQ&c=eEvniauFctOgLOKGJOplqw&r=cTx6f1tAfqPeajYunFWp7_8ot79RnHyNteqzig4fXmA&m=1OMFcIVXCQ-3a2cHjkzeoWw-2B9l6GXi6522rq-fXRo&s=Zg7ORbK0TOC9ZrZ1W5nHutgFgc5wAHA6RlagiMt6NAc&e= <https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_viewvc_llvm-2Dproject_llvm_trunk_test_DebugInfo_gvn.ll-3Frev-3D245588-26view-3Dauto&d=BQIGaQ&c=eEvniauFctOgLOKGJOplqw&r=cTx6f1tAfqPeajYunFWp7_8ot79RnHyNteqzig4fXmA&m=1OMFcIVXCQ-3a2cHjkzeoWw-2B9l6GXi6522rq-fXRo&s=Zg7ORbK0TOC9ZrZ1W5nHutgFgc5wAHA6RlagiMt6NAc&e=>
> > ==============================================================================
> > --- llvm/trunk/test/DebugInfo/gvn.ll (added)
> > +++ llvm/trunk/test/DebugInfo/gvn.ll Thu Aug 20 13:23:56 2015
> > @@ -0,0 +1,135 @@
> > +; RUN: opt < %s -O2 -gvn -S | FileCheck %s
> > +;
> > +; Produced at -O2 from:
> > +; struct context {
> > +; int cur_pid
> > +; };
> > +; int a, b, c, f, d;
> > +; int pid_for_task(int);
> > +; sample(struct context *p1)
> > +; {
> > +; if (c)
> > +; b = a;
> > +; if (a && p1->cur_pid)
> > +; sample_internal();
> > +; }
> > +; callback() {
> > +; f = pid_for_task(d);
> > +; sample(&f);
> > +; }
> > +
> > +target datalayout = "e-m:o-i64:64-i128:128-n32:64-S128"
> > +target triple = "arm64-apple-ios"
> > +
> > +%struct.context = type { i32 }
> > +
> > + at c = common global i32 0, align 4
> > + at a = common global i32 0, align 4
> > + at b = common global i32 0, align 4
> > + at d = common global i32 0, align 4
> > + at f = common global i32 0, align 4
> > +
> > +; Function Attrs: nounwind
> > +declare i32 @sample_internal(...)
> > +
> > +; Function Attrs: nounwind
> > +define i32 @callback() #0 {
> > +entry:
> > + %0 = load i32, i32* @d, align 4, !dbg !37
> > +
> > + ; Verify that the call still has a debug location after GVN.
> > + ; CHECK: %call = tail call i32 @pid_for_task(i32 %0) #{{[0-9]}}, !dbg
> > + %call = tail call i32 @pid_for_task(i32 %0) #3, !dbg !37
> > +
> > + store i32 %call, i32* @f, align 4, !dbg !37
> > + tail call void @llvm.dbg.value(metadata %struct.context* bitcast (i32* @f to %struct.context*), i64 0, metadata !25, metadata !26) #3, !dbg !38
> > + %1 = load i32, i32* @c, align 4, !dbg !40
> > + %tobool.i = icmp eq i32 %1, 0, !dbg !40
> > + %.pr.i = load i32, i32* @a, align 4, !dbg !41
> > + br i1 %tobool.i, label %if.end.i, label %if.then.i, !dbg !42
> > +
> > +if.then.i: ; preds = %entry
> > + store i32 %.pr.i, i32* @b, align 4, !dbg !43
> > + br label %if.end.i, !dbg !43
> > +
> > +if.end.i: ; preds = %if.then.i, %entry
> > + %tobool1.i = icmp eq i32 %.pr.i, 0, !dbg !41
> > +
> > + ; This instruction has no debug location -- in this
> > + ; particular case it was removed by a bug in SimplifyCFG.
>
> ... which has been fixed in r245589.
>
> Ideally we'd have a reproduction that was from IR that wasn't produced by a bug in another pass - but if that's not easy to come by, this is still legit, for sure (we shouldn't crash on any IR input, really - which does sort of make that assertion a bit dodgy,
Not really, Duncan (I think?) added a verifier check to the same effect as the assertion recently, so it is no longer legal to have wrong debug locations. “No debug locations” is more of a gray area of course.
> but at least it expresses a relatively limited constraint which this IR file satisfies, even with this missing location)
>
>
> > + %2 = load i32, i32* @f, align 4
> > +
> > + ; GVN is supposed to replace the load of @f with a direct reference to %call.
> > + ; CHECK: %tobool2.i = icmp eq i32 %call, 0, !dbg
> > + %tobool2.i = icmp eq i32 %2, 0, !dbg !41
> > +
> > + %or.cond = or i1 %tobool1.i, %tobool2.i, !dbg !41
> > + br i1 %or.cond, label %sample.exit, label %if.then.3.i, !dbg !41
> > +
> > +if.then.3.i: ; preds = %if.end.i
> > + %call.i = tail call i32 bitcast (i32 (...)* @sample_internal to i32 ()*)() #3, !dbg !44
> > + br label %sample.exit, !dbg !44
> > +
> > +sample.exit: ; preds = %if.end.i, %if.then.3.i
> > + ret i32 undef, !dbg !45
> > +}
> > +
> > +declare i32 @pid_for_task(i32) #1
> > +
> > +; Function Attrs: nounwind readnone
> > +declare void @llvm.dbg.value(metadata, i64, metadata, metadata) #2
> > +
> > +attributes #0 = { nounwind }
> > +attributes #2 = { nounwind readnone }
> > +attributes #3 = { nounwind }
> > +
> > +!llvm.dbg.cu <https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.dbg.cu&d=BQMFaQ&c=eEvniauFctOgLOKGJOplqw&r=cTx6f1tAfqPeajYunFWp7_8ot79RnHyNteqzig4fXmA&m=tCvabjHLRgtE8pYEwk_4rnKJHHe7ViXrRrU8PtnORI0&s=lRfYUH6akjutgNevAQG4U-M5kYf6yT8W4Lb1_BbJlyw&e=> = !{!0}
> > +!llvm.module.flags = !{!22, !23}
> > +!llvm.ident = !{!24}
> > +
> > +!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 3.8.0 (trunk 244473) (llvm/trunk 244644)", isOptimized: false, runtimeVersion: 0, emissionKind: 1, enums: !2, subprograms: !3, globals: !16)
> > +!1 = !DIFile(filename: "test.c", directory: "/")
> > +!2 = !{}
> > +!3 = !{!4, !13}
> > +!4 = !DISubprogram(name: "sample", scope: !5, file: !5, line: 6, type: !6, isLocal: false, isDefinition: true, scopeLine: 7, flags: DIFlagPrototyped, isOptimized: false, variables: !2)
> > +!5 = !DIFile(filename: "test.i", directory: "/")
> > +!6 = !DISubroutineType(types: !7)
> > +!7 = !{!8, !9}
> > +!8 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
> > +!9 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !10, size: 64, align: 64)
> > +!10 = !DICompositeType(tag: DW_TAG_structure_type, name: "context", file: !5, line: 1, size: 32, align: 32, elements: !11)
> > +!11 = !{!12}
> > +!12 = !DIDerivedType(tag: DW_TAG_member, name: "cur_pid", scope: !10, file: !5, line: 2, baseType: !8, size: 32, align: 32)
> > +!13 = !DISubprogram(name: "callback", scope: !5, file: !5, line: 13, type: !14, isLocal: false, isDefinition: true, scopeLine: 13, isOptimized: false, function: i32 ()* @callback, variables: !2)
> > +!14 = !DISubroutineType(types: !15)
> > +!15 = !{!8}
> > +!16 = !{!17, !18, !19, !20, !21}
> > +!17 = !DIGlobalVariable(name: "a", scope: !0, file: !5, line: 4, type: !8, isLocal: false, isDefinition: true, variable: i32* @a)
> > +!18 = !DIGlobalVariable(name: "b", scope: !0, file: !5, line: 4, type: !8, isLocal: false, isDefinition: true, variable: i32* @b)
> > +!19 = !DIGlobalVariable(name: "c", scope: !0, file: !5, line: 4, type: !8, isLocal: false, isDefinition: true, variable: i32* @c)
> > +!20 = !DIGlobalVariable(name: "f", scope: !0, file: !5, line: 4, type: !8, isLocal: false, isDefinition: true, variable: i32* @f)
> > +!21 = !DIGlobalVariable(name: "d", scope: !0, file: !5, line: 4, type: !8, isLocal: false, isDefinition: true, variable: i32* @d)
> > +!22 = !{i32 2, !"Dwarf Version", i32 2}
> > +!23 = !{i32 2, !"Debug Info Version", i32 3}
> > +!24 = !{!"clang version 3.8.0 (trunk 244473) (llvm/trunk 244644)"}
> > +!25 = !DILocalVariable(name: "p1", arg: 1, scope: !4, file: !5, line: 6, type: !9)
> > +!26 = !DIExpression()
> > +!27 = !DILocation(line: 6, scope: !4)
> > +!28 = !DILocation(line: 8, scope: !29)
> > +!29 = distinct !DILexicalBlock(scope: !4, file: !5, line: 8)
> > +!30 = !DILocation(line: 10, scope: !31)
> > +!31 = distinct !DILexicalBlock(scope: !4, file: !5, line: 10)
> > +!32 = !DILocation(line: 8, scope: !4)
> > +!33 = !DILocation(line: 9, scope: !29)
> > +!34 = !DILocation(line: 10, scope: !4)
> > +!35 = !DILocation(line: 11, scope: !31)
> > +!36 = !DILocation(line: 12, scope: !4)
> > +!37 = !DILocation(line: 14, scope: !13)
> > +!38 = !DILocation(line: 6, scope: !4, inlinedAt: !39)
> > +!39 = distinct !DILocation(line: 15, scope: !13)
> > +!40 = !DILocation(line: 8, scope: !29, inlinedAt: !39)
> > +!41 = !DILocation(line: 10, scope: !31, inlinedAt: !39)
> > +!42 = !DILocation(line: 8, scope: !4, inlinedAt: !39)
> > +!43 = !DILocation(line: 9, scope: !29, inlinedAt: !39)
> > +!44 = !DILocation(line: 11, scope: !31, inlinedAt: !39)
> > +!45 = !DILocation(line: 16, scope: !13)
> >
> >
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