From 9e3b64b9f95aadf57568576712902a272fe66503 Mon Sep 17 00:00:00 2001 From: Fangrui Song Date: Thu, 4 Apr 2024 09:33:18 -0700 Subject: [llvm-objcopy] Add --compress-sections --compress-sections is similar to --compress-debug-sections but applies to arbitrary sections. * `--compress-sections
=none`: decompress sections * `--compress-sections
=[zlib|zstd]`: compress sections with zlib/zstd Like `--remove-section`, the pattern is by default a glob, but a regex when --regex is specified. For `--remove-section` like options, `!` prevents matches and is not dependent on ordering (see `ELF/wildcard-syntax.test`). Since `--compress-sections a=zlib --compress-sections a=none` naturally allows overriding, having an order-independent `!` would be confusing. Therefore, `!` is disallowed. Sections within a segment are effectively immutable. Report an error for an attempt to (de)compress them. `SHF_ALLOC` sections in a relocatable file can be compressed, but linkers usually reject them. Link: https://discourse.llvm.org/t/rfc-compress-arbitrary-sections-with-ld-lld-compress-sections/71674 Pull Request: https://github.com/llvm/llvm-project/pull/85036 --- llvm/docs/CommandGuide/llvm-objcopy.rst | 8 ++ llvm/docs/ReleaseNotes.rst | 4 + llvm/include/llvm/ObjCopy/CommonConfig.h | 3 + llvm/lib/ObjCopy/ELF/ELFObjcopy.cpp | 34 ++++-- .../ELF/compress-sections-within-segment.s | 38 ++++++ .../tools/llvm-objcopy/ELF/compress-sections.s | 128 +++++++++++++++++++++ .../llvm-objcopy/ELF/decompress-sections.test | 29 +++++ llvm/tools/llvm-objcopy/ObjcopyOptions.cpp | 36 ++++++ llvm/tools/llvm-objcopy/ObjcopyOpts.td | 6 + 9 files changed, 278 insertions(+), 8 deletions(-) create mode 100644 llvm/test/tools/llvm-objcopy/ELF/compress-sections-within-segment.s create mode 100644 llvm/test/tools/llvm-objcopy/ELF/compress-sections.s (limited to 'llvm') diff --git a/llvm/docs/CommandGuide/llvm-objcopy.rst b/llvm/docs/CommandGuide/llvm-objcopy.rst index 985d16e..57d6280 100644 --- a/llvm/docs/CommandGuide/llvm-objcopy.rst +++ b/llvm/docs/CommandGuide/llvm-objcopy.rst @@ -309,6 +309,14 @@ them. Compress DWARF debug sections in the output, using the specified format. Supported formats are ``zlib`` and ``zstd``. Use ``zlib`` if ```` is omitted. +.. option:: --compress-sections
= + + Compress or decompress sections matched by ``
`` using the specified + format. Supported formats are ``zlib`` and ``zstd``. Specify ``none`` for + decompression. When a section is matched by multiple options, the last one + wins. A wildcard ``
`` starting with '!' is disallowed. + Sections within a segment cannot be (de)compressed. + .. option:: --decompress-debug-sections Decompress any compressed DWARF debug sections in the output. diff --git a/llvm/docs/ReleaseNotes.rst b/llvm/docs/ReleaseNotes.rst index 7588048..ff7fed9 100644 --- a/llvm/docs/ReleaseNotes.rst +++ b/llvm/docs/ReleaseNotes.rst @@ -182,6 +182,10 @@ Changes to the LLVM tools for ELF input to skip the specified symbols when executing other options that can change a symbol's name, binding or visibility. +* llvm-objcopy now supports ``--compress-sections`` to compress or decompress + arbitrary sections not within a segment. + (`#85036 `_.) + * llvm-profgen now supports COFF+DWARF binaries. This enables Sample-based PGO on Windows using Intel VTune's SEP. For details on usage, see the `end-user documentation for SPGO diff --git a/llvm/include/llvm/ObjCopy/CommonConfig.h b/llvm/include/llvm/ObjCopy/CommonConfig.h index 9d6d5fb..ae08d40 100644 --- a/llvm/include/llvm/ObjCopy/CommonConfig.h +++ b/llvm/include/llvm/ObjCopy/CommonConfig.h @@ -262,6 +262,9 @@ struct CommonConfig { bool DecompressDebugSections = false; DebugCompressionType CompressionType = DebugCompressionType::None; + + SmallVector, 0> + compressSections; }; } // namespace objcopy diff --git a/llvm/lib/ObjCopy/ELF/ELFObjcopy.cpp b/llvm/lib/ObjCopy/ELF/ELFObjcopy.cpp index 205bc1e..f343d14 100644 --- a/llvm/lib/ObjCopy/ELF/ELFObjcopy.cpp +++ b/llvm/lib/ObjCopy/ELF/ELFObjcopy.cpp @@ -215,23 +215,41 @@ static Error dumpSectionToFile(StringRef SecName, StringRef Filename, } Error Object::compressOrDecompressSections(const CommonConfig &Config) { - // Build a list of the debug sections we are going to replace. - // We can't call `AddSection` while iterating over sections, + // Build a list of sections we are going to replace. + // We can't call `addSection` while iterating over sections, // because it would mutate the sections array. SmallVector>, 0> ToReplace; for (SectionBase &Sec : sections()) { - if ((Sec.Flags & SHF_ALLOC) || !StringRef(Sec.Name).starts_with(".debug")) + std::optional CType; + for (auto &[Matcher, T] : Config.compressSections) + if (Matcher.matches(Sec.Name)) + CType = T; + // Handle --compress-debug-sections and --decompress-debug-sections, which + // apply to non-ALLOC debug sections. + if (!(Sec.Flags & SHF_ALLOC) && StringRef(Sec.Name).starts_with(".debug")) { + if (Config.CompressionType != DebugCompressionType::None) + CType = Config.CompressionType; + else if (Config.DecompressDebugSections) + CType = DebugCompressionType::None; + } + if (!CType) continue; + + if (Sec.ParentSegment) + return createStringError( + errc::invalid_argument, + "section '" + Sec.Name + + "' within a segment cannot be (de)compressed"); + if (auto *CS = dyn_cast(&Sec)) { - if (Config.DecompressDebugSections) { + if (*CType == DebugCompressionType::None) ToReplace.emplace_back( &Sec, [=] { return &addSection(*CS); }); - } - } else if (Config.CompressionType != DebugCompressionType::None) { - ToReplace.emplace_back(&Sec, [&, S = &Sec] { + } else if (*CType != DebugCompressionType::None) { + ToReplace.emplace_back(&Sec, [=, S = &Sec] { return &addSection( - CompressedSection(*S, Config.CompressionType, Is64Bits)); + CompressedSection(*S, *CType, Is64Bits)); }); } } diff --git a/llvm/test/tools/llvm-objcopy/ELF/compress-sections-within-segment.s b/llvm/test/tools/llvm-objcopy/ELF/compress-sections-within-segment.s new file mode 100644 index 0000000..064ffca --- /dev/null +++ b/llvm/test/tools/llvm-objcopy/ELF/compress-sections-within-segment.s @@ -0,0 +1,38 @@ +## Disallow (de)compression for sections within a segment as they are +## effectively immutable. +# RUN: rm -rf %t && mkdir %t && cd %t +# RUN: yaml2obj %s -o a +# RUN: not llvm-objcopy a /dev/null --compress-sections .text=zlib 2>&1 | FileCheck %s --implicit-check-not=error: + +# CHECK: error: 'a': section '.text' within a segment cannot be (de)compressed + +# RUN: not llvm-objcopy a /dev/null --compress-sections foo=none 2>&1 | FileCheck %s --check-prefix=CHECK2 --implicit-check-not=error: + +# CHECK2: error: 'a': section 'foo' within a segment cannot be (de)compressed + +## There is an error even if 'foo' is already compressed with zlib. +# RUN: not llvm-objcopy a /dev/null --compress-sections foo=zlib 2>&1 | FileCheck %s --check-prefix=CHECK3 --implicit-check-not=error: + +# CHECK3: error: 'a': section 'foo' within a segment cannot be (de)compressed + +--- !ELF +FileHeader: + Class: ELFCLASS64 + Data: ELFDATA2LSB + Type: ET_EXEC + Machine: EM_X86_64 +ProgramHeaders: + - Type: PT_LOAD + FirstSec: .text + LastSec: foo + Align: 0x1000 + Offset: 0x1000 +Sections: + - Name: .text + Type: SHT_PROGBITS + Offset: 0x1000 + Content: C3 + - Name: foo + Type: SHT_PROGBITS + Flags: [ SHF_COMPRESSED ] + Content: 010000000000000040000000000000000100000000000000789cd36280002d3269002f800151 diff --git a/llvm/test/tools/llvm-objcopy/ELF/compress-sections.s b/llvm/test/tools/llvm-objcopy/ELF/compress-sections.s new file mode 100644 index 0000000..e6fa860 --- /dev/null +++ b/llvm/test/tools/llvm-objcopy/ELF/compress-sections.s @@ -0,0 +1,128 @@ +# REQUIRES: x86-registered-target, zlib, zstd + +# RUN: rm -rf %t && mkdir %t && cd %t +# RUN: llvm-mc -filetype=obj -triple=x86_64 %s -o a.o +## '*0=none' wins because it is the last. '*0' sections are decompressed (if originally compressed) or kept unchanged (if uncompressed). +## No section is named 'nomatch'. The third option is a no-op. +# RUN: llvm-objcopy a.o out --compress-sections='*0=zlib' --compress-sections '*0=none' --compress-sections 'nomatch=none' 2>&1 | count 0 +# RUN: llvm-readelf -S out | FileCheck %s --check-prefix=CHECK1 + +# CHECK1: Name Type Address Off Size ES Flg Lk Inf Al +# CHECK1: .text PROGBITS [[#%x,TEXT:]] [[#%x,]] [[#%x,]] 00 AX 0 0 4 +# CHECK1: foo0 PROGBITS [[#%x,FOO0:]] [[#%x,]] [[#%x,]] 00 A 0 0 8 +# CHECK1-NEXT: .relafoo0 RELA [[#%x,]] [[#%x,]] [[#%x,]] 18 I 11 3 8 +# CHECK1-NEXT: foo1 PROGBITS [[#%x,FOO1:]] [[#%x,]] [[#%x,]] 00 A 0 0 8 +# CHECK1-NEXT: .relafoo1 RELA [[#%x,]] [[#%x,]] [[#%x,]] 18 I 11 5 8 +# CHECK1: nonalloc0 PROGBITS 0000000000000000 [[#%x,]] [[#%x,]] 00 0 0 8 +# CHECK1-NEXT: .relanonalloc0 RELA [[#%x,]] [[#%x,]] [[#%x,]] 18 I 11 7 8 +# CHECK1-NEXT: nonalloc1 PROGBITS 0000000000000000 [[#%x,]] [[#%x,]] 00 0 0 8 +# CHECK1-NEXT: .debug_str PROGBITS 0000000000000000 [[#%x,]] [[#%x,]] 01 MS 0 0 1 + +## Mixing zlib and zstd. +# RUN: llvm-objcopy a.o out2 --compress-sections '*c0=zlib' --compress-sections .debug_str=zstd +# RUN: llvm-readelf -Sr -x nonalloc0 -x .debug_str out2 2>&1 | FileCheck %s --check-prefix=CHECK2 +# RUN: llvm-readelf -z -x nonalloc0 -x .debug_str out2 | FileCheck %s --check-prefix=CHECK2DE + +# CHECK2: Name Type Address Off Size ES Flg Lk Inf Al +# CHECK2: .text PROGBITS [[#%x,TEXT:]] [[#%x,]] [[#%x,]] 00 AX 0 0 4 +# CHECK2: foo0 PROGBITS [[#%x,FOO0:]] [[#%x,]] [[#%x,]] 00 A 0 0 8 +# CHECK2-NEXT: .relafoo0 RELA [[#%x,]] [[#%x,]] [[#%x,]] 18 I 11 3 8 +# CHECK2-NEXT: foo1 PROGBITS [[#%x,FOO1:]] [[#%x,]] [[#%x,]] 00 A 0 0 8 +# CHECK2-NEXT: .relafoo1 RELA [[#%x,]] [[#%x,]] [[#%x,]] 18 I 11 5 8 +# CHECK2: nonalloc0 PROGBITS 0000000000000000 [[#%x,]] [[#%x,]] 00 C 0 0 8 +# CHECK2-NEXT: .relanonalloc0 RELA [[#%x,]] [[#%x,]] [[#%x,]] 18 IC 11 7 8 +# CHECK2-NEXT: nonalloc1 PROGBITS 0000000000000000 [[#%x,]] [[#%x,]] 00 0 0 8 +# CHECK2-NEXT: .debug_str PROGBITS 0000000000000000 [[#%x,]] [[#%x,]] 01 MSC 0 0 8 + +## llvm-readelf -r doesn't support SHF_COMPRESSED SHT_RELA. +# CHECK2: warning: {{.*}}: unable to read relocations from SHT_RELA section with index 8: section [index 8] has an invalid sh_size ([[#]]) which is not a multiple of its sh_entsize (24) + +# CHECK2: Hex dump of section 'nonalloc0': +## zlib with ch_size=0x10 +# CHECK2-NEXT: 01000000 00000000 10000000 00000000 +# CHECK2-NEXT: 08000000 00000000 {{.*}} +# CHECK2: Hex dump of section '.debug_str': +## zstd with ch_size=0x38 +# CHECK2-NEXT: 02000000 00000000 38000000 00000000 +# CHECK2-NEXT: 01000000 00000000 {{.*}} + +# CHECK2DE: Hex dump of section 'nonalloc0': +# CHECK2DE-NEXT: 0x00000000 00000000 00000000 00000000 00000000 ................ +# CHECK2DE-EMPTY: +# CHECK2DE-NEXT: Hex dump of section '.debug_str': +# CHECK2DE-NEXT: 0x00000000 41414141 41414141 41414141 41414141 AAAAAAAAAAAAAAAA + +## --decompress-debug-sections takes precedence, even if it is before --compress-sections. +# RUN: llvm-objcopy a.o out3 --decompress-debug-sections --compress-sections .debug_str=zstd +# RUN: llvm-readelf -S out3 | FileCheck %s --check-prefix=CHECK3 + +# CHECK3: .debug_str PROGBITS 0000000000000000 [[#%x,]] [[#%x,]] 01 MS 0 0 1 + +# RUN: llvm-objcopy a.o out4 --compress-sections '*0=zlib' +# RUN: llvm-readelf -S out4 | FileCheck %s --check-prefix=CHECK4 + +# CHECK4: Name Type Address Off Size ES Flg Lk Inf Al +# CHECK4: .text PROGBITS [[#%x,TEXT:]] [[#%x,]] [[#%x,]] 00 AX 0 0 4 +# CHECK4: foo0 PROGBITS [[#%x,FOO0:]] [[#%x,]] [[#%x,]] 00 AC 0 0 8 +# CHECK4-NEXT: .relafoo0 RELA [[#%x,]] [[#%x,]] [[#%x,]] 18 IC 11 3 8 +# CHECK4-NEXT: foo1 PROGBITS [[#%x,FOO1:]] [[#%x,]] [[#%x,]] 00 A 0 0 8 +# CHECK4-NEXT: .relafoo1 RELA [[#%x,]] [[#%x,]] [[#%x,]] 18 I 11 5 8 +# CHECK4: nonalloc0 PROGBITS 0000000000000000 [[#%x,]] [[#%x,]] 00 C 0 0 8 +# CHECK4-NEXT: .relanonalloc0 RELA [[#%x,]] [[#%x,]] [[#%x,]] 18 IC 11 7 8 +# CHECK4-NEXT: nonalloc1 PROGBITS 0000000000000000 [[#%x,]] [[#%x,]] 00 0 0 8 +# CHECK4-NEXT: .debug_str PROGBITS 0000000000000000 [[#%x,]] [[#%x,]] 01 MS 0 0 1 + +## If a section is already compressed, compression request for another format is ignored. +# RUN: llvm-objcopy a.o out5 --compress-sections 'nonalloc0=zlib' +# RUN: llvm-readelf -x nonalloc0 out5 | FileCheck %s --check-prefix=CHECK5 +# RUN: llvm-objcopy out5 out5a --compress-sections 'nonalloc0=zstd' +# RUN: cmp out5 out5a + +# CHECK5: Hex dump of section 'nonalloc0': +## zlib with ch_size=0x10 +# CHECK5-NEXT: 01000000 00000000 10000000 00000000 +# CHECK5-NEXT: 08000000 00000000 {{.*}} + +# RUN: not llvm-objcopy --compress-sections=foo a.o out 2>&1 | \ +# RUN: FileCheck %s --check-prefix=ERR1 --implicit-check-not=error: +# ERR1: error: --compress-sections: parse error, not 'section-glob=[none|zlib|zstd]' + +# RUN: llvm-objcopy --compress-sections 'a[=zlib' a.o out 2>&1 | \ +# RUN: FileCheck %s --check-prefix=ERR2 --implicit-check-not=error: +# ERR2: warning: invalid glob pattern, unmatched '[' + +# RUN: not llvm-objcopy a.o out --compress-sections='.debug*=zlib-gabi' --compress-sections='.debug*=' 2>&1 | \ +# RUN: FileCheck -check-prefix=ERR3 %s +# ERR3: error: invalid or unsupported --compress-sections format: .debug*=zlib-gabi + +# RUN: not llvm-objcopy a.o out --compress-sections='!.debug*=zlib' 2>&1 | \ +# RUN: FileCheck -check-prefix=ERR4 %s +# ERR4: error: --compress-sections: negative pattern is unsupported + +.globl _start +_start: + ret + +.section foo0,"a" +.balign 8 +.quad .text-. +.quad .text-. +.section foo1,"a" +.balign 8 +.quad .text-. +.quad .text-. +.section nonalloc0,"" +.balign 8 +.quad .text+1 +.quad .text+2 +sym0: +.section nonalloc1,"" +.balign 8 +.quad 42 +sym1: + +.section .debug_str,"MS",@progbits,1 +.Linfo_string0: + .asciz "AAAAAAAAAAAAAAAAAAAAAAAAAAA" +.Linfo_string1: + .asciz "BBBBBBBBBBBBBBBBBBBBBBBBBBB" diff --git a/llvm/test/tools/llvm-objcopy/ELF/decompress-sections.test b/llvm/test/tools/llvm-objcopy/ELF/decompress-sections.test index 4258ddb..d9f4f38 100644 --- a/llvm/test/tools/llvm-objcopy/ELF/decompress-sections.test +++ b/llvm/test/tools/llvm-objcopy/ELF/decompress-sections.test @@ -4,6 +4,8 @@ # RUN: yaml2obj %s -o %t # RUN: llvm-objcopy --decompress-debug-sections %t %t.de # RUN: llvm-readelf -S %t.de | FileCheck %s +# RUN: llvm-objcopy --compress-sections '*nonalloc=none' --compress-sections .debugx=none %t %t.1.de +# RUN: cmp %t.de %t.1.de # CHECK: Name Type Address Off Size ES Flg Lk Inf Al # CHECK: .debug_alloc PROGBITS 0000000000000000 [[#%x,]] [[#%x,]] 00 AC 0 0 0 @@ -11,6 +13,33 @@ # CHECK-NEXT: .debugx PROGBITS 0000000000000000 [[#%x,]] [[#%x,]] 00 0 0 1 # CHECK-NEXT: nodebug PROGBITS 0000000000000000 [[#%x,]] [[#%x,]] 00 C 0 0 0 +# RUN: llvm-objcopy --compress-sections '.debug*=none' %t %t2.de +# RUN: llvm-readelf -S -x .debug_alloc -x .debug_nonalloc -x .debugx %t2.de | FileCheck %s --check-prefix=CHECK2 + +# CHECK2: Name Type Address Off Size ES Flg Lk Inf Al +# CHECK2: .debug_alloc PROGBITS 0000000000000000 [[#%x,]] [[#%x,]] 00 A 0 0 1 +# CHECK2-NEXT: .debug_nonalloc PROGBITS 0000000000000000 [[#%x,]] [[#%x,]] 00 0 0 1 +# CHECK2-NEXT: .debugx PROGBITS 0000000000000000 [[#%x,]] [[#%x,]] 00 0 0 1 +# CHECK2-NEXT: nodebug PROGBITS 0000000000000000 [[#%x,]] [[#%x,]] 00 C 0 0 0 + +# CHECK2: Hex dump of section '.debug_alloc': +# CHECK2-NEXT: 0x00000000 2a000000 00000000 2a000000 00000000 *.......*....... +# CHECK2-NEXT: 0x00000010 2a000000 00000000 2a000000 00000000 *.......*....... +# CHECK2-NEXT: 0x00000020 2a000000 00000000 2a000000 00000000 *.......*....... +# CHECK2-NEXT: 0x00000030 2a000000 00000000 2a000000 00000000 *.......*....... +# CHECK2-EMPTY: +# CHECK2: Hex dump of section '.debug_nonalloc': +# CHECK2-NEXT: 0x00000000 2a000000 00000000 2a000000 00000000 *.......*....... +# CHECK2-NEXT: 0x00000010 2a000000 00000000 2a000000 00000000 *.......*....... +# CHECK2-NEXT: 0x00000020 2a000000 00000000 2a000000 00000000 *.......*....... +# CHECK2-NEXT: 0x00000030 2a000000 00000000 2a000000 00000000 *.......*....... +# CHECK2-EMPTY: +# CHECK2-NEXT: Hex dump of section '.debugx': +# CHECK2-NEXT: 0x00000000 2a000000 00000000 2a000000 00000000 *.......*....... +# CHECK2-NEXT: 0x00000010 2a000000 00000000 2a000000 00000000 *.......*....... +# CHECK2-NEXT: 0x00000020 2a000000 00000000 2a000000 00000000 *.......*....... +# CHECK2-NEXT: 0x00000030 2a000000 00000000 2a000000 00000000 *.......*....... + --- !ELF FileHeader: Class: ELFCLASS64 diff --git a/llvm/tools/llvm-objcopy/ObjcopyOptions.cpp b/llvm/tools/llvm-objcopy/ObjcopyOptions.cpp index 7269c51..70e8546 100644 --- a/llvm/tools/llvm-objcopy/ObjcopyOptions.cpp +++ b/llvm/tools/llvm-objcopy/ObjcopyOptions.cpp @@ -736,6 +736,42 @@ objcopy::parseObjcopyOptions(ArrayRef RawArgsArr, return createStringError(errc::invalid_argument, Reason); } + for (const auto *A : InputArgs.filtered(OBJCOPY_compress_sections)) { + SmallVector Fields; + StringRef(A->getValue()).split(Fields, '='); + if (Fields.size() != 2 || Fields[1].empty()) { + return createStringError( + errc::invalid_argument, + A->getSpelling() + + ": parse error, not 'section-glob=[none|zlib|zstd]'"); + } + + auto Type = StringSwitch(Fields[1]) + .Case("zlib", DebugCompressionType::Zlib) + .Case("zstd", DebugCompressionType::Zstd) + .Default(DebugCompressionType::None); + if (Type == DebugCompressionType::None && Fields[1] != "none") { + return createStringError( + errc::invalid_argument, + "invalid or unsupported --compress-sections format: %s", + A->getValue()); + } + + auto &P = Config.compressSections.emplace_back(); + P.second = Type; + auto Matcher = + NameOrPattern::create(Fields[0], SectionMatchStyle, ErrorCallback); + // =none allows overriding a previous =zlib or =zstd. Reject negative + // patterns, which would be confusing. + if (Matcher && !Matcher->isPositiveMatch()) { + return createStringError( + errc::invalid_argument, + "--compress-sections: negative pattern is unsupported"); + } + if (Error E = P.first.addMatcher(std::move(Matcher))) + return std::move(E); + } + Config.AddGnuDebugLink = InputArgs.getLastArgValue(OBJCOPY_add_gnu_debuglink); // The gnu_debuglink's target is expected to not change or else its CRC would // become invalidated and get rejected. We can avoid recalculating the diff --git a/llvm/tools/llvm-objcopy/ObjcopyOpts.td b/llvm/tools/llvm-objcopy/ObjcopyOpts.td index be02616..4bc80eb 100644 --- a/llvm/tools/llvm-objcopy/ObjcopyOpts.td +++ b/llvm/tools/llvm-objcopy/ObjcopyOpts.td @@ -35,6 +35,12 @@ def : Flag<["--"], "compress-debug-sections">, Alias, AliasArgs<["zlib"]>; def decompress_debug_sections : Flag<["--"], "decompress-debug-sections">, HelpText<"Decompress DWARF debug sections">; +defm compress_sections + : Eq<"compress-sections", + "Compress or decompress sections using specified format. Supported " + "formats: zlib, zstd. Specify 'none' for decompression">, + MetaVarName<"=">; + defm split_dwo : Eq<"split-dwo", "Equivalent to --extract-dwo and as the output file and no other options, " "and then --strip-dwo on the input file">, -- cgit v1.1