From 783006ec19853403b8fe799e4c1b9496cb03504a Mon Sep 17 00:00:00 2001 From: Bjorn Pettersson Date: Tue, 6 Mar 2018 08:47:07 +0000 Subject: [PATCH] [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 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@326769 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/LiveDebugVariables.cpp | 38 +++++- test/DebugInfo/X86/dbg-value-inlined-parameter.ll | 6 +- .../X86/live-debug-vars-discard-invalid.mir | 141 +++++++++++++++++++++ 3 files changed, 181 insertions(+), 4 deletions(-) create mode 100644 test/DebugInfo/X86/live-debug-vars-discard-invalid.mir diff --git a/lib/CodeGen/LiveDebugVariables.cpp b/lib/CodeGen/LiveDebugVariables.cpp index 09168b6..f3fcd00 100644 --- a/lib/CodeGen/LiveDebugVariables.cpp +++ b/lib/CodeGen/LiveDebugVariables.cpp @@ -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 +555,10 @@ bool LDVImpl::handleDebugValue(MachineInstr &MI, SlotIndex Idx) { const DIExpression *Expr = MI.getDebugExpression(); UserValue *UV = getUserValue(Var, Expr, MI.getDebugLoc()); - UV->addDef(Idx, MI.getOperand(0), IsIndirect); + if (!Discard) + UV->addDef(Idx, MI.getOperand(0), IsIndirect); + else + UV->addDef(Idx, MachineOperand::CreateReg(0U, RegState::Debug), false); return true; } diff --git a/test/DebugInfo/X86/dbg-value-inlined-parameter.ll b/test/DebugInfo/X86/dbg-value-inlined-parameter.ll index 9954039..e83cf0a 100644 --- a/test/DebugInfo/X86/dbg-value-inlined-parameter.ll +++ b/test/DebugInfo/X86/dbg-value-inlined-parameter.ll @@ -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 diff --git a/test/DebugInfo/X86/live-debug-vars-discard-invalid.mir b/test/DebugInfo/X86/live-debug-vars-discard-invalid.mir new file mode 100644 index 0000000..abc21bc --- /dev/null +++ b/test/DebugInfo/X86/live-debug-vars-discard-invalid.mir @@ -0,0 +1,141 @@ +# RUN: llc -mtriple=x86_64-linux-gnu -start-before greedy -stop-after virtregrewriter -o - %s | FileCheck %s + +--- | + ; ModuleID = '' + 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 -- 1.8.3.1