Commit 233e9e7a authored by Tom Stellard's avatar Tom Stellard
Browse files

Merging r326769 and r326780: 

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r326769 | bjope | 2018-03-06 00:47:07 -0800 (Tue, 06 Mar 2018) | 28 lines

[DebugInfo] Discard invalid DBG_VALUE instructions in LiveDebugVariables

Summary:
This is a workaround for pr36417
https://bugs.llvm.org/show_bug.cgi?id=36417

LiveDebugVariables will now verify that the DBG_VALUE instructions
are sane (prior to register allocation) by asking LIS if a virtual
register used in the DBG_VALUE is live (or dead def) in the slot
index before the DBG_VALUE. If it isn't sane the DBG_VALUE is
discarded.

One pass that was identified as introducing non-sane DBG_VALUE
instructtons, when analysing pr36417, was the DAG->DAG Instruction
Selection. It sometimes inserts DBG_VALUE instructions referring to
a virtual register that is defined later in the same basic block.
So it is a use before def kind of problem. The DBG_VALUE is
typically inserted in the beginning of a basic block when this
happens. The problem can be seen in the test case
test/DebugInfo/X86/dbg-value-inlined-parameter.ll

Reviewers: aprantl, rnk, probinson

Reviewed By: aprantl

Subscribers: vsk, davide, alexcrichton, Ka-Ka, eraman, llvm-commits, JDevlieghere

Differential Revision: https://reviews.llvm.org/D43956
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r326780 | bjope | 2018-03-06 05:23:28 -0800 (Tue, 06 Mar 2018) | 6 lines

Fixup for rL326769 (RegState::Debug is being truncated to a bool)

I obviously messed up arguments to MachineOperand::CreateReg
in rL326769. This should make it work as intended.

Thanks to RKSimon for spotting this.
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llvm-svn: 329668
parent d9b94079

llvm/lib/CodeGen/LiveDebugVariables.cpp

+40 −1
Original line number Diff line number Diff line
@@ -514,6 +514,39 @@ bool LDVImpl::handleDebugValue(MachineInstr &MI, SlotIndex Idx) { 
    return false;

  }



  // Detect invalid DBG_VALUE instructions, with a debug-use of a virtual

  // register that hasn't been defined yet. If we do not remove those here, then

  // the re-insertion of the DBG_VALUE instruction after register allocation

  // will be incorrect.

  // TODO: If earlier passes are corrected to generate sane debug information

  // (and if the machine verifier is improved to catch this), then these checks

  // could be removed or replaced by asserts.

  bool Discard = false;

  if (MI.getOperand(0).isReg() &&

      TargetRegisterInfo::isVirtualRegister(MI.getOperand(0).getReg())) {

    const unsigned Reg = MI.getOperand(0).getReg();

    if (!LIS->hasInterval(Reg)) {

      // The DBG_VALUE is described by a virtual register that does not have a

      // live interval. Discard the DBG_VALUE.

      Discard = true;

      DEBUG(dbgs() << "Discarding debug info (no LIS interval): "

            << Idx << " " << MI);

    } else {

      // The DBG_VALUE is only valid if either Reg is live out from Idx, or Reg

      // is defined dead at Idx (where Idx is the slot index for the instruction

      // preceeding the DBG_VALUE).

      const LiveInterval &LI = LIS->getInterval(Reg);

      LiveQueryResult LRQ = LI.Query(Idx);

      if (!LRQ.valueOutOrDead()) {

        // We have found a DBG_VALUE with the value in a virtual register that

        // is not live. Discard the DBG_VALUE.

        Discard = true;

        DEBUG(dbgs() << "Discarding debug info (reg not live): "

              << Idx << " " << MI);

      }

    }

  }



  // Get or create the UserValue for (variable,offset) here.

  bool IsIndirect = MI.getOperand(1).isImm();

  if (IsIndirect)
@@ -522,7 +555,13 @@ bool LDVImpl::handleDebugValue(MachineInstr &MI, SlotIndex Idx) { 
  const DIExpression *Expr = MI.getDebugExpression();

  UserValue *UV =

      getUserValue(Var, Expr, MI.getDebugLoc());

  if (!Discard)

    UV->addDef(Idx, MI.getOperand(0), IsIndirect);

  else {

    MachineOperand MO = MachineOperand::CreateReg(0U, false);

    MO.setIsDebug();

    UV->addDef(Idx, MO, false);

  }

  return true;

}

llvm/test/DebugInfo/X86/dbg-value-inlined-parameter.ll

+3 −3
Original line number Diff line number Diff line
@@ -32,10 +32,10 @@ 
;CHECK-NEXT: DW_AT_call_line



;CHECK: DW_TAG_formal_parameter

;FIXME: Linux shouldn't drop this parameter either...

;CHECK-NOT: DW_TAG

;DARWIN:   DW_AT_abstract_origin {{.*}} "sp"

;DARWIN: DW_TAG_formal_parameter

;FIXME: Shouldn't drop this parameter...

;XCHECK:   DW_AT_abstract_origin {{.*}} "sp"

;XCHECK: DW_TAG_formal_parameter

;CHECK: DW_AT_abstract_origin {{.*}} "nums"

;CHECK-NOT: DW_TAG_formal_parameter

llvm/test/DebugInfo/X86/live-debug-vars-discard-invalid.mir

0 → 100644
+141 −0
Original line number Diff line number Diff line 
# RUN: llc -mtriple=x86_64-linux-gnu -start-before greedy -stop-after virtregrewriter -o - %s | FileCheck %s



--- |

  ; ModuleID = '<stdin>'

  source_filename = "test/DebugInfo/X86/dbg-value-inlined-parameter.ll"

  target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"

  target triple = "x86_64-apple-darwin"



  %struct.S1 = type { float*, i32 }



  @p = common global %struct.S1 zeroinitializer, align 8, !dbg !0



  ; Function Attrs: nounwind optsize ssp

  define void @foobar() !dbg !15 {

  entry:

    tail call void @llvm.dbg.value(metadata %struct.S1* @p, metadata !18, metadata !DIExpression()) , !dbg !25

    ret void, !dbg !32

  }



  ; Function Attrs: nounwind readnone speculatable

  declare void @llvm.dbg.value(metadata, metadata, metadata) #2



  !llvm.dbg.cu = !{!2}

  !llvm.module.flags = !{!14}



  !0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())

  !1 = !DIGlobalVariable(name: "p", scope: !2, file: !3, line: 14, type: !6, isLocal: false, isDefinition: true)

  !2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 2.9 (trunk 125693)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, retainedTypes: !4, globals: !5, imports: !4)

  !3 = !DIFile(filename: "nm2.c", directory: "/private/tmp")

  !4 = !{}

  !5 = !{!0}

  !6 = !DIDerivedType(tag: DW_TAG_typedef, name: "S1", scope: !2, file: !3, line: 4, baseType: !7)

  !7 = !DICompositeType(tag: DW_TAG_structure_type, name: "S1", scope: !2, file: !3, line: 1, size: 128, align: 64, elements: !8)

  !8 = !{!9, !12}

  !9 = !DIDerivedType(tag: DW_TAG_member, name: "m", scope: !3, file: !3, line: 2, baseType: !10, size: 64, align: 64)

  !10 = !DIDerivedType(tag: DW_TAG_pointer_type, scope: !2, baseType: !11, size: 64, align: 64)

  !11 = !DIBasicType(name: "float", size: 32, align: 32, encoding: DW_ATE_float)

  !12 = !DIDerivedType(tag: DW_TAG_member, name: "nums", scope: !3, file: !3, line: 3, baseType: !13, size: 32, align: 32, offset: 64)

  !13 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)

  !14 = !{i32 1, !"Debug Info Version", i32 3}

  !15 = distinct !DISubprogram(name: "foobar", scope: !3, file: !3, line: 15, type: !16, isLocal: false, isDefinition: true, virtualIndex: 6, isOptimized: true, unit: !2)

  !16 = !DISubroutineType(types: !17)

  !17 = !{null}

  !18 = !DILocalVariable(name: "sp", arg: 1, scope: !19, file: !3, line: 7, type: !24)

  !19 = distinct !DISubprogram(name: "foo", scope: !3, file: !3, line: 8, type: !20, isLocal: false, isDefinition: true, scopeLine: 8, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: true, unit: !2, variables: !22)

  !20 = !DISubroutineType(types: !21)

  !21 = !{!13}

  !22 = !{!18, !23}

  !23 = !DILocalVariable(name: "nums", arg: 2, scope: !19, file: !3, line: 7, type: !13)

  !24 = !DIDerivedType(tag: DW_TAG_pointer_type, scope: !2, baseType: !6, size: 64, align: 64)

  !25 = !DILocation(line: 7, column: 13, scope: !19, inlinedAt: !26)

  !26 = !DILocation(line: 16, column: 3, scope: !27)

  !27 = distinct !DILexicalBlock(scope: !15, file: !3, line: 15, column: 15)

  !32 = !DILocation(line: 17, column: 1, scope: !27)



...

---

name:            foobar

tracksRegLiveness: true

body:             |

  bb.0:

    %1:gr64 = IMPLICIT_DEF

    %2:gr64 = IMPLICIT_DEF



  bb.1:

    ; This DBG_VALUE will be discarded (use before def of %0).

    DBG_VALUE debug-use %0, debug-use %noreg, !18, !DIExpression(), debug-location !25

    %0:gr64 = IMPLICIT_DEF

    %0:gr64 = IMPLICIT_DEF

    %0:gr64 = IMPLICIT_DEF

    %0:gr64 = IMPLICIT_DEF



  bb.2:

    ; This DBG_VALUE will be discarded (%1 is defined earlier, but it is not live in, so we do not know where %1 is stored).

    DBG_VALUE debug-use %1, debug-use %noreg, !18, !DIExpression(), debug-location !25

    %1:gr64 = IMPLICIT_DEF

    %1:gr64 = IMPLICIT_DEF

    %1:gr64 = IMPLICIT_DEF

    %1:gr64 = IMPLICIT_DEF

    ; This DBG_VALUE is kept, even if %1 is dead, it was defined in the prev instruction,

    ; so the value should be available for as long as the register allocated to %1 is live.

    DBG_VALUE debug-use %1, debug-use %noreg, !18, !DIExpression(), debug-location !25



  bb.3:

    %1:gr64 = IMPLICIT_DEF

    DBG_VALUE 0, debug-use %noreg, !23, !DIExpression(), debug-location !25

    ; This DBG_VALUE is kept, even if %1 is dead, it was defined in the prev non-dbg instruction,

    ; so the value should be available for as long as the register allocated to %1 is live.

    DBG_VALUE debug-use %1, debug-use %noreg, !18, !DIExpression(), debug-location !25



  bb.4:

    ; All DBG_VALUEs here should survive. %2 is livein as it was defined in bb.0, and it has use/def in the BTS64rr instruction.

    DBG_VALUE debug-use %2, debug-use %noreg, !18, !DIExpression(), debug-location !25

    %2:gr64 = BTS64rr %2, 0, implicit-def %eflags

    DBG_VALUE 0, debug-use %noreg, !23, !DIExpression(), debug-location !25

    DBG_VALUE debug-use %2, debug-use %noreg, !18, !DIExpression(), debug-location !25

    %2:gr64 = BTS64rr %2, 0, implicit-def %eflags

    DBG_VALUE debug-use %2, debug-use %noreg, !18, !DIExpression(), debug-location !25

    %2:gr64 = BTS64rr %2, 0, implicit-def %eflags

    DBG_VALUE debug-use %2, debug-use %noreg, !18, !DIExpression(), debug-location !25



  bb.5:

    RET 0, debug-location !32

...



# CHECK-LABEL: name: foobar



# CHECK-LABEL: bb.1:

## After solving https://bugs.llvm.org/show_bug.cgi?id=36579 we expect to get a

##   DBG_VALUE debug-use %noreg

## here.

# CHECK-NOT:    DBG_VALUE



# CHECK-LABEL: bb.2:

## After solving https://bugs.llvm.org/show_bug.cgi?id=36579 we expect to get a

##   DBG_VALUE debug-use %noreg

## here.

# CHECK-NOT:    DBG_VALUE

# CHECK:        dead renamable %rcx = IMPLICIT_DEF

# CHECK-NEXT:   dead renamable %rcx = IMPLICIT_DEF

# CHECK-NEXT:   dead renamable %rcx = IMPLICIT_DEF

# CHECK-NEXT:   dead renamable %rcx = IMPLICIT_DEF

# CHECK-NEXT:   DBG_VALUE debug-use %rcx, debug-use %noreg, !18, !DIExpression()



# CHECK-LABEL: bb.3:

# CHECK:        dead renamable %rcx = IMPLICIT_DEF

# CHECK-NEXT:   DBG_VALUE 0, debug-use %noreg, !23, !DIExpression()

# CHECK-NEXT:   DBG_VALUE debug-use %rcx, debug-use %noreg, !18, !DIExpression()



# CHECK-LABEL: bb.4:

# CHECK:        liveins: %rax

# CHECK:        DBG_VALUE debug-use %rax, debug-use %noreg, !18, !DIExpression()

# CHECK-NEXT:   renamable %rax = BTS64rr killed renamable %rax, 0, implicit-def %eflags

# CHECK-NEXT:   DBG_VALUE 0, debug-use %noreg, !23, !DIExpression()

# CHECK-NEXT:   DBG_VALUE debug-use %rax, debug-use %noreg, !18, !DIExpression()

# CHECK-NEXT:   renamable %rax = BTS64rr killed renamable %rax, 0, implicit-def %eflags

# CHECK-NEXT:   DBG_VALUE debug-use %rax, debug-use %noreg, !18, !DIExpression()

# CHECK-NEXT:   dead renamable %rax = BTS64rr killed renamable %rax, 0, implicit-def %eflags



# CHECK-LABEL: bb.5:

# CHECK-NEXT:   RET 0