[llvm] r204958 - DebugInfo: Support for compressed debug info sections
Matheus Almeida
Matheus.Almeida at imgtec.com
Fri Mar 28 07:15:36 PDT 2014
Hi,
I'm getting a segmentation fault on my local build running the test added by this patch. I can't give you much more information because that build doesn't have debug info but I could get a clean call stack which I've attached to this e-mail.
In the meantime I'll start another build with debug info and I'll try to replicate this issue.
Regards,
Matheus
-----Original Message-----
From: llvm-commits-bounces at cs.uiuc.edu [mailto:llvm-commits-bounces at cs.uiuc.edu] On Behalf Of Evgeniy Stepanov
Sent: 28 March 2014 08:01
To: David Blaikie
Cc: llvm-commits
Subject: Re: [llvm] r204958 - DebugInfo: Support for compressed debug info sections
With this change we get an assertion failure on the bots:
lib/MC/MCAssembler.cpp:245: const SmallVectorImpl<char>
&llvm::MCCompressedFragment::getCompressedContents() const: Assertion `Success == zlib::StatusOK' failed.
http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-bootstrap/builds/2813/steps/check-llvm%20msan/logs/stdio
On Fri, Mar 28, 2014 at 12:45 AM, David Blaikie <dblaikie at gmail.com> wrote:
> Author: dblaikie
> Date: Thu Mar 27 15:45:58 2014
> New Revision: 204958
>
> URL: http://llvm.org/viewvc/llvm-project?rev=204958&view=rev
> Log:
> DebugInfo: Support for compressed debug info sections
>
> 1) When creating a .debug_* section and instead create a .zdebug_
> section.
> 2) When creating a fragment in a .zdebug_* section, make it a compressed
> fragment.
> 3) When computing the size of a compressed section, compress the data
> and use the size of the compressed data.
> 4) Emit the compressed bytes.
>
> Also, check that only if a section has a compressed fragment, then
> that is the only fragment in the section.
>
> Assert-fail if the fragment's data is modified after it is compressed.
>
> Initial review on llvm-commits by Eric Christopher and Rafael Espindola.
>
> Added:
> llvm/trunk/test/MC/ELF/compression.s
> Modified:
> llvm/trunk/include/llvm/MC/MCAssembler.h
> llvm/trunk/lib/MC/MCAsmInfo.cpp
> llvm/trunk/lib/MC/MCAssembler.cpp
> llvm/trunk/lib/MC/MCContext.cpp
> llvm/trunk/lib/MC/MCObjectStreamer.cpp
> llvm/trunk/tools/llvm-mc/llvm-mc.cpp
>
> Modified: llvm/trunk/include/llvm/MC/MCAssembler.h
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/MC/MCAssem
> bler.h?rev=204958&r1=204957&r2=204958&view=diff
> ======================================================================
> ========
> --- llvm/trunk/include/llvm/MC/MCAssembler.h (original)
> +++ llvm/trunk/include/llvm/MC/MCAssembler.h Thu Mar 27 15:45:58 2014
> @@ -51,6 +51,7 @@ public:
> enum FragmentType {
> FT_Align,
> FT_Data,
> + FT_Compressed,
> FT_CompactEncodedInst,
> FT_Fill,
> FT_Relaxable,
> @@ -160,6 +161,7 @@ public:
> return false;
> case MCFragment::FT_Relaxable:
> case MCFragment::FT_CompactEncodedInst:
> + case MCFragment::FT_Compressed:
> case MCFragment::FT_Data:
> return true;
> }
> @@ -194,7 +196,8 @@ public:
>
> static bool classof(const MCFragment *F) {
> MCFragment::FragmentType Kind = F->getKind();
> - return Kind == MCFragment::FT_Relaxable || Kind == MCFragment::FT_Data;
> + return Kind == MCFragment::FT_Relaxable || Kind == MCFragment::FT_Data ||
> + Kind == MCFragment::FT_Compressed;
> }
> };
>
> @@ -213,6 +216,11 @@ class MCDataFragment : public MCEncodedF
>
> /// Fixups - The list of fixups in this fragment.
> SmallVector<MCFixup, 4> Fixups;
> +protected:
> + MCDataFragment(MCFragment::FragmentType FType, MCSectionData *SD = 0)
> + : MCEncodedFragmentWithFixups(FType, SD), HasInstructions(false),
> + AlignToBundleEnd(false) {}
> +
> public:
> MCDataFragment(MCSectionData *SD = 0)
> : MCEncodedFragmentWithFixups(FT_Data, SD), @@ -246,10 +254,21 @@
> public:
> const_fixup_iterator fixup_end() const override {return
> Fixups.end();}
>
> static bool classof(const MCFragment *F) {
> - return F->getKind() == MCFragment::FT_Data;
> + return F->getKind() == MCFragment::FT_Data ||
> + F->getKind() == MCFragment::FT_Compressed;
> }
> };
>
> +class MCCompressedFragment: public MCDataFragment {
> + mutable SmallVector<char, 32> CompressedContents;
> +public:
> + MCCompressedFragment(MCSectionData *SD = nullptr)
> + : MCDataFragment(FT_Compressed, SD) {}
> + const SmallVectorImpl<char> &getCompressedContents() const;
> + using MCDataFragment::getContents;
> + SmallVectorImpl<char> &getContents() override; };
> +
> /// This is a compact (memory-size-wise) fragment for holding an
> encoded /// instruction (non-relaxable) that has no fixups
> registered. When applicable, /// it can be used instead of
> MCDataFragment and lead to lower memory
>
> Modified: llvm/trunk/lib/MC/MCAsmInfo.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCAsmInfo.cpp?re
> v=204958&r1=204957&r2=204958&view=diff
> ======================================================================
> ========
> --- llvm/trunk/lib/MC/MCAsmInfo.cpp (original)
> +++ llvm/trunk/lib/MC/MCAsmInfo.cpp Thu Mar 27 15:45:58 2014
> @@ -100,6 +100,8 @@ MCAsmInfo::MCAsmInfo() {
> // architecture basis.
> // - The target subclasses for AArch64, ARM, and X86 handle these cases
> UseIntegratedAssembler = false;
> +
> + CompressDebugSections = false;
> }
>
> MCAsmInfo::~MCAsmInfo() {
>
> Modified: llvm/trunk/lib/MC/MCAssembler.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCAssembler.cpp?
> rev=204958&r1=204957&r2=204958&view=diff
> ======================================================================
> ========
> --- llvm/trunk/lib/MC/MCAssembler.cpp (original)
> +++ llvm/trunk/lib/MC/MCAssembler.cpp Thu Mar 27 15:45:58 2014
> @@ -28,6 +28,9 @@
> #include "llvm/Support/LEB128.h"
> #include "llvm/Support/TargetRegistry.h"
> #include "llvm/Support/raw_ostream.h"
> +#include "llvm/Support/MemoryBuffer.h"
> +#include "llvm/Support/Compression.h"
> +#include "llvm/Support/Host.h"
>
> using namespace llvm;
>
> @@ -230,6 +233,39 @@ MCEncodedFragmentWithFixups::~MCEncodedF
>
> /* *** */
>
> +const SmallVectorImpl<char>
> +&MCCompressedFragment::getCompressedContents() const {
> + assert(getParent()->size() == 1 &&
> + "Only compress sections containing a single fragment");
> + if (CompressedContents.empty()) {
> + std::unique_ptr<MemoryBuffer> CompressedSection;
> + zlib::Status Success =
> + zlib::compress(StringRef(getContents().data(), getContents().size()),
> + CompressedSection);
> + (void)Success;
> + assert(Success == zlib::StatusOK);
> + CompressedContents.push_back('Z');
> + CompressedContents.push_back('L');
> + CompressedContents.push_back('I');
> + CompressedContents.push_back('B');
> + uint64_t Size = getContents().size();
> + if (sys::IsLittleEndianHost)
> + Size = sys::SwapByteOrder(Size);
> + CompressedContents.append(reinterpret_cast<char *>(&Size),
> + reinterpret_cast<char *>(&Size + 1));
> + CompressedContents.append(CompressedSection->getBuffer().begin(),
> + CompressedSection->getBuffer().end());
> + }
> + return CompressedContents;
> +}
> +
> +SmallVectorImpl<char> &MCCompressedFragment::getContents() {
> + assert(CompressedContents.empty() &&
> + "Fragment contents should not be altered after
> +compression");
> + return MCDataFragment::getContents(); }
> +
> +/* *** */
> +
> MCSectionData::MCSectionData() : Section(0) {}
>
> MCSectionData::MCSectionData(const MCSection &_Section, MCAssembler
> *A) @@ -430,6 +466,8 @@ uint64_t MCAssembler::computeFragmentSiz
> case MCFragment::FT_Relaxable:
> case MCFragment::FT_CompactEncodedInst:
> return cast<MCEncodedFragment>(F).getContents().size();
> + case MCFragment::FT_Compressed:
> + return
> + cast<MCCompressedFragment>(F).getCompressedContents().size();
> case MCFragment::FT_Fill:
> return cast<MCFillFragment>(F).getSize();
>
> @@ -618,6 +656,11 @@ static void writeFragment(const MCAssemb
> break;
> }
>
> + case MCFragment::FT_Compressed:
> + ++stats::EmittedDataFragments;
> + OW->WriteBytes(cast<MCCompressedFragment>(F).getCompressedContents());
> + break;
> +
> case MCFragment::FT_Data:
> ++stats::EmittedDataFragments;
> writeFragmentContents(F, OW);
> @@ -694,6 +737,7 @@ void MCAssembler::writeSectionData(const
> ie = SD->end(); it != ie; ++it) {
> switch (it->getKind()) {
> default: llvm_unreachable("Invalid fragment in virtual
> section!");
> + case MCFragment::FT_Compressed:
> case MCFragment::FT_Data: {
> // Check that we aren't trying to write a non-zero contents (or fixups)
> // into a virtual section. This is to support clients which
> use standard @@ -1021,6 +1065,8 @@ void MCFragment::dump() {
> switch (getKind()) {
> case MCFragment::FT_Align: OS << "MCAlignFragment"; break;
> case MCFragment::FT_Data: OS << "MCDataFragment"; break;
> + case MCFragment::FT_Compressed:
> + OS << "MCCompressedFragment"; break;
> case MCFragment::FT_CompactEncodedInst:
> OS << "MCCompactEncodedInstFragment"; break;
> case MCFragment::FT_Fill: OS << "MCFillFragment"; break; @@
> -1047,6 +1093,7 @@ void MCFragment::dump() {
> << " MaxBytesToEmit:" << AF->getMaxBytesToEmit() << ">";
> break;
> }
> + case MCFragment::FT_Compressed:
> case MCFragment::FT_Data: {
> const MCDataFragment *DF = cast<MCDataFragment>(this);
> OS << "\n ";
>
> Modified: llvm/trunk/lib/MC/MCContext.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCContext.cpp?re
> v=204958&r1=204957&r2=204958&view=diff
> ======================================================================
> ========
> --- llvm/trunk/lib/MC/MCContext.cpp (original)
> +++ llvm/trunk/lib/MC/MCContext.cpp Thu Mar 27 15:45:58 2014
> @@ -37,13 +37,13 @@ typedef std::map<SectionGroupPair, const
>
> MCContext::MCContext(const MCAsmInfo *mai, const MCRegisterInfo *mri,
> const MCObjectFileInfo *mofi, const SourceMgr *mgr,
> - bool DoAutoReset) :
> - SrcMgr(mgr), MAI(mai), MRI(mri), MOFI(mofi),
> - Allocator(), Symbols(Allocator), UsedNames(Allocator),
> - NextUniqueID(0),
> - CurrentDwarfLoc(0,0,0,DWARF2_FLAG_IS_STMT,0,0),
> - DwarfLocSeen(false), GenDwarfForAssembly(false),
> GenDwarfFileNumber(0),
> - AllowTemporaryLabels(true), DwarfCompileUnitID(0),
> AutoReset(DoAutoReset) {
> + bool DoAutoReset)
> + : SrcMgr(mgr), MAI(mai), MRI(mri), MOFI(mofi), Allocator(),
> + Symbols(Allocator), UsedNames(Allocator), NextUniqueID(0),
> + CurrentDwarfLoc(0, 0, 0, DWARF2_FLAG_IS_STMT, 0, 0), DwarfLocSeen(false),
> + GenDwarfForAssembly(false), GenDwarfFileNumber(0),
> + AllowTemporaryLabels(true), DwarfCompileUnitID(0),
> + AutoReset(DoAutoReset) {
>
> error_code EC = llvm::sys::fs::current_path(CompilationDir);
> if (EC)
> @@ -251,6 +251,11 @@ getELFSection(StringRef Section, unsigne
> ELFUniquingMap = new ELFUniqueMapTy();
> ELFUniqueMapTy &Map = *(ELFUniqueMapTy*)ELFUniquingMap;
>
> + SmallString<32> ZDebugName;
> + if (MAI->compressDebugSections() && Section.startswith(".debug_") &&
> + Section != ".debug_frame")
> + Section = (".z" + Section.drop_front(1)).toStringRef(ZDebugName);
> +
> // Do the lookup, if we have a hit, return it.
> std::pair<ELFUniqueMapTy::iterator, bool> Entry = Map.insert(
> std::make_pair(SectionGroupPair(Section, Group), (MCSectionELF
> *)0));
>
> Modified: llvm/trunk/lib/MC/MCObjectStreamer.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCObjectStreamer
> .cpp?rev=204958&r1=204957&r2=204958&view=diff
> ======================================================================
> ========
> --- llvm/trunk/lib/MC/MCObjectStreamer.cpp (original)
> +++ llvm/trunk/lib/MC/MCObjectStreamer.cpp Thu Mar 27 15:45:58 2014
> @@ -20,6 +20,7 @@
> #include "llvm/MC/MCSection.h"
> #include "llvm/MC/MCSymbol.h"
> #include "llvm/Support/ErrorHandling.h"
> +#include "llvm/MC/MCSectionELF.h"
> using namespace llvm;
>
> MCObjectStreamer::MCObjectStreamer(MCContext &Context, MCAsmBackend
> &TAB, @@ -63,7 +64,11 @@ MCDataFragment *MCObjectStreamer::getOrC
> // When bundling is enabled, we don't want to add data to a fragment that
> // already has instructions (see MCELFStreamer::EmitInstToData for details)
> if (!F || (Assembler->isBundlingEnabled() && F->hasInstructions())) {
> - F = new MCDataFragment();
> + const auto *Sec = dyn_cast<MCSectionELF>(&getCurrentSectionData()->getSection());
> + if (Sec && Sec->getSectionName().startswith(".zdebug_"))
> + F = new MCCompressedFragment();
> + else
> + F = new MCDataFragment();
> insert(F);
> }
> return F;
>
> Added: llvm/trunk/test/MC/ELF/compression.s
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/ELF/compression
> .s?rev=204958&view=auto
> ======================================================================
> ========
> --- llvm/trunk/test/MC/ELF/compression.s (added)
> +++ llvm/trunk/test/MC/ELF/compression.s Thu Mar 27 15:45:58 2014
> @@ -0,0 +1,18 @@
> +// RUN: llvm-mc -filetype=obj -compress-debug-sections -triple
> +x86_64-pc-linux-gnu %s -o - | llvm-objdump -s - | FileCheck %s
> +
> +// CHECK: Contents of section .zdebug_line:
> +// Check for the 'ZLIB' file magic at the start of the section //
> +CHECK-NEXT: ZLIB // We shouldn't compress the debug_frame section,
> +since it can be relaxed // CHECK: Contents of section .debug_frame //
> +CHECK-NOT: ZLIB
> +
> + .section .debug_line,"", at progbits
> + .text
> +foo:
> + .cfi_startproc
> + .file 1 "Driver.ii"
> + .loc 1 2 0
> + nop
> + .cfi_endproc
> + .cfi_sections .debug_frame
>
> Modified: llvm/trunk/tools/llvm-mc/llvm-mc.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-mc/llvm-mc.c
> pp?rev=204958&r1=204957&r2=204958&view=diff
> ======================================================================
> ========
> --- llvm/trunk/tools/llvm-mc/llvm-mc.cpp (original)
> +++ llvm/trunk/tools/llvm-mc/llvm-mc.cpp Thu Mar 27 15:45:58 2014
> @@ -50,6 +50,9 @@ static cl::opt<bool> ShowEncoding("show-encoding",
> cl::desc("Show instruction encodings"));
>
> static cl::opt<bool>
> +CompressDebugSections("compress-debug-sections", cl::desc("Compress
> +DWARF debug sections"));
> +
> +static cl::opt<bool>
> ShowInst("show-inst", cl::desc("Show internal instruction
> representation"));
>
> static cl::opt<bool>
> @@ -381,6 +384,9 @@ int main(int argc, char **argv) {
> std::unique_ptr<MCAsmInfo> MAI(TheTarget->createMCAsmInfo(*MRI, TripleName));
> assert(MAI && "Unable to create target asm info!");
>
> + if (CompressDebugSections)
> + MAI->setCompressDebugSections(true);
> +
> // FIXME: This is not pretty. MCContext has a ptr to MCObjectFileInfo and
> // MCObjectFileInfo needs a MCContext reference in order to initialize itself.
> std::unique_ptr<MCObjectFileInfo> MOFI(new MCObjectFileInfo());
>
>
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