[llvm] r198851 - Prototype of skeleton type units for fission

Kostya Serebryany kcc at google.com
Thu Jan 9 00:27:23 PST 2014


David,

I observe a use-of-uninitialized somewhere near the code you were touching
in the recent changes.
Could you please take a look?
This causes asan to SEGV:
./bin/llc /home/kcc/llvm/test/DebugInfo/X86/generate-odr-hash.ll
-split-dwarf=Enable -o test/DebugInfo/X86/Output/generate-odr-hash.ll.tmp
-filetype=obj -O0 -generate-type-units -mtriple=x86_64-unknown-linux-gnu
ASAN:SIGSEGV
=================================================================
==22210==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000
(pc 0x000001879397 sp 0x7fff102262c0 bp 0x7fff102263b0 T0)
    #0 0x1879396 in getOffset
/home/kcc/llvm/lib/CodeGen/AsmPrinter/DIE.h:145
    #1 0x1879396 in llvm::DwarfTypeUnit::emitHeader(llvm::MCSection const*,
llvm::MCSymbol const*) const
/home/kcc/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp:1991
    #2 0x182e3c7 in llvm::DwarfFile::emitUnits(llvm::DwarfDebug*,
llvm::MCSection const*, llvm::MCSymbol const*)
/home/kcc/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp:2123
    #3 0x180f651 in emitDebugInfo
/home/kcc/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp:2134
    #4 0x180f651 in llvm::DwarfDebug::endModule()
/home/kcc/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp:1144
    #5 0x17d604f in llvm::AsmPrinter::doFinalization(llvm::Module&)
/home/kcc/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp:918
    #6 0x2bc94f8 in llvm::FPPassManager::doFinalization(llvm::Module&)
/home/kcc/llvm/lib/IR/LegacyPassManager.cpp:1575
    #7 0x2bca102 in runOnModule
/home/kcc/llvm/lib/IR/LegacyPassManager.cpp:1632
    #8 0x2bca102 in llvm::legacy::PassManagerImpl::run(llvm::Module&)
/home/kcc/llvm/lib/IR/LegacyPassManager.cpp:1710
    #9 0x62bb93 in compileModule /home/kcc/llvm/tools/llc/llc.cpp:376
    #10 0x62bb93 in main /home/kcc/llvm/tools/llc/llc.cpp:197

valgrind tells this:
==22278== Conditional jump or move depends on uninitialised value(s)
==22278==    at 0xA6C55C: llvm::DwarfTypeUnit::emitHeader(llvm::MCSection
const*, llvm::MCSymbol const*) const
==22278==    by 0xA56250: llvm::DwarfFile::emitUnits(llvm::DwarfDebug*,
llvm::MCSection const*, llvm::MCSymbol const*)
==22278==    by 0xA4E186: llvm::DwarfDebug::endModule()
==22278==    by 0xA3E7E7: llvm::AsmPrinter::doFinalization(llvm::Module&)
==22278==    by 0x101C03D:
llvm::FPPassManager::doFinalization(llvm::Module&)
==22278==    by 0x101C578:
llvm::legacy::PassManagerImpl::run(llvm::Module&)
==22278==    by 0x101C7E9: llvm::legacy::PassManager::run(llvm::Module&)
==22278==    by 0x55D088: main
==22278==  Uninitialised value was created by a heap allocation
==22278==    at 0x4C2C9EE: operator new(unsigned long)
(vg_replace_malloc.c:319)
==22278==    by 0xA5714A:
llvm::DwarfDebug::addDwarfTypeUnitType(llvm::DICompileUnit,
llvm::StringRef, llvm::DIE*, llvm::DICompositeType)
==22278==    by 0xA66DE6: llvm::DwarfUnit::getOrCreateTypeDIE(llvm::MDNode
const*)
==22278==    by 0xA6920D: llvm::DwarfUnit::addType(llvm::DIE*,
llvm::DIType, llvm::dwarf::Attribute)
==22278==    by 0xA6AC04:
llvm::DwarfCompileUnit::createGlobalVariableDIE(llvm::DIGlobalVariable)
==22278==    by 0xA49104: llvm::DwarfDebug::beginModule()
==22278==    by 0xA48DAE: llvm::DwarfDebug::DwarfDebug(llvm::AsmPrinter*,
llvm::Module*)
==22278==    by 0xA3A3EB: llvm::AsmPrinter::doInitialization(llvm::Module&)
==22278==    by 0x101BF75:
llvm::FPPassManager::doInitialization(llvm::Module&)
==22278==    by 0x101C36D:
llvm::legacy::PassManagerImpl::run(llvm::Module&)
==22278==    by 0x101C7E9: llvm::legacy::PassManager::run(llvm::Module&)
==22278==    by 0x55D088: main

(our msan bot is down, I suspect msan would catch this as well)




On Thu, Jan 9, 2014 at 9:08 AM, David Blaikie <dblaikie at gmail.com> wrote:

> Author: dblaikie
> Date: Wed Jan  8 23:08:28 2014
> New Revision: 198851
>
> URL: http://llvm.org/viewvc/llvm-project?rev=198851&view=rev
> Log:
> Prototype of skeleton type units for fission
>
> Modified:
>     llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
>     llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h
>     llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
>     llvm/trunk/lib/MC/MCObjectFileInfo.cpp
>     llvm/trunk/test/DebugInfo/X86/generate-odr-hash.ll
>
> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp?rev=198851&r1=198850&r2=198851&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp (original)
> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp Wed Jan  8 23:08:28
> 2014
> @@ -2976,6 +2976,21 @@ DwarfCompileUnit *DwarfDebug::constructS
>    return NewCU;
>  }
>
> +// This DIE has the following attributes: DW_AT_comp_dir, DW_AT_dwo_name,
> +// DW_AT_addr_base.
> +DwarfTypeUnit *DwarfDebug::constructSkeletonTU(const DwarfTypeUnit *TU) {
> +
> +  DIE *Die = new DIE(dwarf::DW_TAG_type_unit);
> +  DwarfTypeUnit *NewTU = new DwarfTypeUnit(
> +      TU->getUniqueID(), Die, TU->getCUNode(), Asm, this,
> &SkeletonHolder);
> +  NewTU->setTypeSignature(TU->getTypeSignature());
> +  NewTU->initSection(
> +
>  Asm->getObjFileLowering().getDwarfTypesSection(TU->getTypeSignature()));
> +
> +  initSkeletonUnit(TU, Die, NewTU);
> +  return NewTU;
> +}
> +
>  // Emit the .debug_info.dwo section for separated dwarf. This contains the
>  // compile units that would normally be in debug_info.
>  void DwarfDebug::emitDebugInfoDWO() {
> @@ -3018,8 +3033,6 @@ void DwarfDebug::addDwarfTypeUnitType(DI
>      NewTU->addUInt(UnitDie, dwarf::DW_AT_language, dwarf::DW_FORM_data2,
>                     CUNode.getLanguage());
>
> -    DIE *Die = NewTU->createTypeDIE(CTy);
> -
>      MD5 Hash;
>      Hash.update(Identifier);
>      // ... take the least significant 8 bytes and return those. Our MD5
> @@ -3029,7 +3042,10 @@ void DwarfDebug::addDwarfTypeUnitType(DI
>      Hash.final(Result);
>      uint64_t Signature = *reinterpret_cast<support::ulittle64_t *>(Result
> + 8);
>      NewTU->setTypeSignature(Signature);
> -    NewTU->setType(Die);
> +    if (useSplitDwarf())
> +      NewTU->setSkeleton(constructSkeletonTU(NewTU));
> +
> +    NewTU->setType(NewTU->createTypeDIE(CTy));
>
>      NewTU->initSection(
>          useSplitDwarf()
>
> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h?rev=198851&r1=198850&r2=198851&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h (original)
> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h Wed Jan  8 23:08:28 2014
> @@ -596,6 +596,10 @@ class DwarfDebug : public AsmPrinterHand
>    /// section.
>    DwarfCompileUnit *constructSkeletonCU(const DwarfCompileUnit *CU);
>
> +  /// \brief Construct the split debug info compile unit for the debug
> info
> +  /// section.
> +  DwarfTypeUnit *constructSkeletonTU(const DwarfTypeUnit *TU);
> +
>    /// \brief Emit the debug info dwo section.
>    void emitDebugInfoDWO();
>
>
> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp?rev=198851&r1=198850&r2=198851&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp (original)
> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp Wed Jan  8 23:08:28
> 2014
> @@ -1987,7 +1987,9 @@ void DwarfTypeUnit::emitHeader(const MCS
>    Asm->OutStreamer.AddComment("Type Signature");
>    Asm->OutStreamer.EmitIntValue(TypeSignature, sizeof(TypeSignature));
>    Asm->OutStreamer.AddComment("Type DIE Offset");
> -  Asm->OutStreamer.EmitIntValue(Ty->getOffset(), sizeof(Ty->getOffset()));
> +  // In a skeleton type unit there is no type DIE so emit a zero offset.
> +  Asm->OutStreamer.EmitIntValue(Ty ? Ty->getOffset() : 0,
> +                                sizeof(Ty->getOffset()));
>  }
>
>  void DwarfTypeUnit::initSection(const MCSection *Section) {
>
> Modified: llvm/trunk/lib/MC/MCObjectFileInfo.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCObjectFileInfo.cpp?rev=198851&r1=198850&r2=198851&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/MC/MCObjectFileInfo.cpp (original)
> +++ llvm/trunk/lib/MC/MCObjectFileInfo.cpp Wed Jan  8 23:08:28 2014
> @@ -726,8 +726,9 @@ const MCSection *MCObjectFileInfo::getDw
>
>  const MCSection *
>  MCObjectFileInfo::getDwarfTypesDWOSection(uint64_t Hash) const {
> -  return Ctx->getELFSection(".debug_types.dwo", ELF::SHT_GROUP, 0,
> -                            SectionKind::getMetadata(), 0, utostr(Hash));
> +  return Ctx->getELFSection(".debug_types.dwo", ELF::SHT_PROGBITS,
> +                            ELF::SHF_GROUP, SectionKind::getMetadata(), 0,
> +                            utostr(Hash));
>  }
>
>  void MCObjectFileInfo::InitEHFrameSection() {
>
> Modified: llvm/trunk/test/DebugInfo/X86/generate-odr-hash.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/generate-odr-hash.ll?rev=198851&r1=198850&r2=198851&view=diff
>
> ==============================================================================
> --- llvm/trunk/test/DebugInfo/X86/generate-odr-hash.ll (original)
> +++ llvm/trunk/test/DebugInfo/X86/generate-odr-hash.ll Wed Jan  8 23:08:28
> 2014
> @@ -1,7 +1,10 @@
>  ; REQUIRES: object-emission
>
>  ; RUN: llc %s -o %t -filetype=obj -O0 -generate-type-units
> -mtriple=x86_64-unknown-linux-gnu
> -; RUN: llvm-dwarfdump %t | FileCheck %s
> +; RUN: llvm-dwarfdump %t | FileCheck --check-prefix=CHECK
> --check-prefix=SINGLE %s
> +
> +; RUN: llc %s -split-dwarf=Enable -o %t -filetype=obj -O0
> -generate-type-units -mtriple=x86_64-unknown-linux-gnu
> +; RUN: llvm-dwarfdump %t | FileCheck --check-prefix=CHECK
> --check-prefix=FISSION %s
>
>  ; Generated from:
>  ; struct bar {};
> @@ -43,7 +46,8 @@
>
>  ; wombat wom;
>
> -; CHECK-LABEL: .debug_info contents:
> +; SINGLE-LABEL: .debug_info contents:
> +; FISSION-LABEL: .debug_info.dwo contents:
>  ; CHECK: Compile Unit: length = [[CU_SIZE:[0-9a-f]+]]
>
>  ; CHECK: DW_TAG_structure_type
> @@ -53,18 +57,32 @@
>
>  ; Ensure the CU-local type 'walrus' is not placed in a type unit.
>  ; CHECK: DW_TAG_structure_type
> -; CHECK-NEXT: debug_str{{.*}}"walrus"
> +; CHECK-NEXT: DW_AT_name{{.*}}"walrus"
>  ; CHECK-NEXT: DW_AT_byte_size
>  ; CHECK-NEXT: DW_AT_decl_file
>  ; CHECK-NEXT: DW_AT_decl_line
>
> -; CHECK-LABEL: .debug_types contents:
> +; FISSION-LABEL: .debug_types contents:
> +; FISSION-NOT: type_signature
> +; FISSION-LABEL: type_signature = 0x1d02f3be30cc5688
> +; FISSION: DW_TAG_type_unit
> +; FISSION: DW_AT_GNU_dwo_name{{.*}}"bar.dwo"
> +; FISSION: DW_AT_comp_dir{{.*}}"/tmp/dbginfo"
> +; FISSION-NOT: type_signature
> +; FISSION-LABEL: type_signature = 0xb04af47397402e77
> +; FISSION-NOT: type_signature
> +; FISSION-LABEL: type_signature = 0xfd756cee88f8a118
> +; FISSION-NOT: type_signature
> +; FISSION-LABEL: type_signature = 0xe94f6d3843e62d6b
> +
> +; SINGLE-LABEL: .debug_types contents:
> +; FISSION-LABEL: .debug_types.dwo contents:
>
>  ; Check that we generate a hash for bar and the value.
>  ; CHECK-NOT: type_signature
>  ; CHECK-LABEL: type_signature = 0x1d02f3be30cc5688
>  ; CHECK: DW_TAG_structure_type
> -; CHECK-NEXT: debug_str{{.*}}"bar"
> +; CHECK-NEXT: DW_AT_name{{.*}}"bar"
>
>
>  ; Check that we generate a hash for fluffy and the value.
> @@ -72,13 +90,13 @@
>  ; CHECK-LABEL: type_signature = 0xb04af47397402e77
>  ; CHECK-NOT: DW_AT_GNU_odr_signature [DW_FORM_data8]
> (0x9a0124d5a0c21c52)
>  ; CHECK: DW_TAG_namespace
> -; CHECK-NEXT: debug_str{{.*}}"echidna"
> +; CHECK-NEXT: DW_AT_name{{.*}}"echidna"
>  ; CHECK: DW_TAG_namespace
> -; CHECK-NEXT: debug_str{{.*}}"capybara"
> +; CHECK-NEXT: DW_AT_name{{.*}}"capybara"
>  ; CHECK: DW_TAG_namespace
> -; CHECK-NEXT: debug_str{{.*}}"mongoose"
> +; CHECK-NEXT: DW_AT_name{{.*}}"mongoose"
>  ; CHECK: DW_TAG_class_type
> -; CHECK-NEXT: debug_str{{.*}}"fluffy"
> +; CHECK-NEXT: DW_AT_name{{.*}}"fluffy"
>
>  ; Check that we generate a hash for wombat and the value, but not for the
>  ; anonymous type contained within.
> @@ -86,7 +104,7 @@
>  ; CHECK-LABEL: type_signature = 0xfd756cee88f8a118
>  ; CHECK-NOT: DW_AT_GNU_odr_signature [DW_FORM_data8] (0x685bcc220141e9d7)
>  ; CHECK: DW_TAG_structure_type
> -; CHECK-NEXT: debug_str{{.*}}"wombat"
> +; CHECK-NEXT: DW_AT_name{{.*}}"wombat"
>
>  ; CHECK-NOT: type_signature
>  ; CHECK-LABEL: type_signature = 0xe94f6d3843e62d6b
> @@ -100,7 +118,7 @@
>  ; CHECK-NOT: DW_AT_name
>  ; CHECK-NOT: DW_AT_GNU_odr_signature
>  ; CHECK: DW_TAG_member
> -; CHECK-NEXT: debug_str{{.*}}"a"
> +; CHECK-NEXT: DW_AT_name{{.*}}"a"
>
>  ; Use the unit size as a rough hash/identifier for the unit we're dealing
> with
>  ; it happens to be unambiguous at the moment, but it's hardly ideal.
> @@ -110,17 +128,21 @@
>  ; CHECK-NEXT: Offset Name
>  ; CHECK-NEXT: "walrus"
>  ; Type unit for 'bar'
> -; CHECK-NEXT: unit_size = 0x00000023
> +; SINGLE-NEXT: unit_size = 0x00000023
> +; FISSION-NEXT: unit_size = 0x00000024
>  ; CHECK-NEXT: Offset Name
>  ; CHECK-NEXT: "bar"
> -; CHECK-NEXT: unit_size = 0x0000005d
> +; SINGLE-NEXT: unit_size = 0x0000005d
> +; FISSION-NEXT: unit_size = 0x00000024
>  ; CHECK-NEXT: Offset Name
>  ; CHECK-NEXT: "int"
>  ; CHECK-NEXT: "echidna::capybara::mongoose::fluffy"
> -; CHECK-NEXT: unit_size = 0x0000003a
> +; SINGLE-NEXT: unit_size = 0x0000003a
> +; FISSION-NEXT: unit_size = 0x00000024
>  ; CHECK-NEXT: Offset Name
>  ; CHECK-NEXT: "wombat"
> -; CHECK-NEXT: unit_size = 0x0000004b
> +; SINGLE-NEXT: unit_size = 0x0000004b
> +; FISSION-NEXT: unit_size = 0x00000024
>  ; CHECK-NEXT: Offset Name
>  ; CHECK-NEXT: "int"
>
> @@ -179,7 +201,7 @@ attributes #1 = { nounwind readnone }
>  !llvm.module.flags = !{!42, !54}
>  !llvm.ident = !{!43}
>
> -!0 = metadata !{i32 786449, metadata !1, i32 4, metadata !"clang version
> 3.4 ", i1 false, metadata !"", i32 0, metadata !2, metadata !3, metadata
> !20, metadata !37, metadata !2, metadata !""} ; [ DW_TAG_compile_unit ]
> [/tmp/dbginfo/bar.cpp] [DW_LANG_C_plus_plus]
> +!0 = metadata !{i32 786449, metadata !1, i32 4, metadata !"clang version
> 3.4 ", i1 false, metadata !"", i32 0, metadata !2, metadata !3, metadata
> !20, metadata !37, metadata !2, metadata !"bar.dwo"} ; [
> DW_TAG_compile_unit ] [/tmp/dbginfo/bar.cpp] [DW_LANG_C_plus_plus]
>  !1 = metadata !{metadata !"bar.cpp", metadata !"/tmp/dbginfo"}
>  !2 = metadata !{i32 0}
>  !3 = metadata !{metadata !4, metadata !5, metadata !13, metadata !16}
>
>
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> llvm-commits at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
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