[ELF] Remove support for legacy .zdebug sections
.zdebug is unlikely used any longer: gcc -gz switched from legacy .zdebug to SHF_COMPRESSED with binutils 2.26 (2016), which has been several years. clang 14 dropped -gz=zlib-gnu support. According to Debian Code Search (`gz=zlib-gnu`), no project uses -gz=zlib-gnu. Remove .zdebug support to (a) simplify code and (b) allow removal of llvm-mc's --compress-debug-sections=zlib-gnu. In case the old object file `a.o` uses .zdebug, run `objcopy --decompress-debug-sections a.o` Reviewed By: peter.smith Differential Revision: https://reviews.llvm.org/D126793
This commit is contained in:
Fangrui Song
parent
dfa9221aa7
commit
e09f77d394
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@ -70,11 +70,9 @@ InputSectionBase::InputSectionBase(InputFile *file, uint64_t flags,
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fatal(toString(this) + ": sh_addralign is not a power of 2");
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this->alignment = v;
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// In ELF, each section can be compressed by zlib, and if compressed,
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// section name may be mangled by appending "z" (e.g. ".zdebug_info").
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// If that's the case, demangle section name so that we can handle a
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// section as if it weren't compressed.
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if ((flags & SHF_COMPRESSED) || name.startswith(".zdebug")) {
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// If SHF_COMPRESSED is set, parse the header. The legacy .zdebug format is no
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// longer supported.
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if (flags & SHF_COMPRESSED) {
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if (!zlib::isAvailable())
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error(toString(file) + ": contains a compressed section, " +
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"but zlib is not available");
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@ -204,29 +202,6 @@ OutputSection *SectionBase::getOutputSection() {
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// by zlib-compressed data. This function parses a header to initialize
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// `uncompressedSize` member and remove the header from `rawData`.
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template <typename ELFT> void InputSectionBase::parseCompressedHeader() {
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// Old-style header
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if (!(flags & SHF_COMPRESSED)) {
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assert(name.startswith(".zdebug"));
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if (!toStringRef(rawData).startswith("ZLIB")) {
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error(toString(this) + ": corrupted compressed section header");
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return;
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}
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rawData = rawData.slice(4);
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if (rawData.size() < 8) {
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error(toString(this) + ": corrupted compressed section header");
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return;
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}
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uncompressedSize = read64be(rawData.data());
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rawData = rawData.slice(8);
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// Restore the original section name.
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// (e.g. ".zdebug_info" -> ".debug_info")
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name = saver().save("." + name.substr(2));
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return;
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}
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flags &= ~(uint64_t)SHF_COMPRESSED;
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// New-style header
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@ -387,7 +387,7 @@ static_assert(sizeof(InputSection) <= 160, "InputSection is too big");
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inline bool isDebugSection(const InputSectionBase &sec) {
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return (sec.flags & llvm::ELF::SHF_ALLOC) == 0 &&
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(sec.name.startswith(".debug") || sec.name.startswith(".zdebug"));
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sec.name.startswith(".debug");
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}
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// The list of all input sections.
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@ -38,6 +38,9 @@ Breaking changes
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* ``-d`` is now ignored.
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* If a prevailing COMDAT group defines STB_WEAK symbol, having a STB_GLOBAL symbol in a non-prevailing group is now rejected with a diagnostic.
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(`D120626 <https://reviews.llvm.org/D120626>`_)
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* Support for the legacy ``.zdebug`` format has been removed. Run
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``objcopy --decompress-debug-sections`` in case old object files use ``.zdebug``.
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(`D126793 <https://reviews.llvm.org/D126793>`_)
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COFF Improvements
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-----------------
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@ -22,37 +22,11 @@
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# ZLIB-NEXT: EntrySize: 1
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# ZLIB-NEXT: }
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# RUN: llvm-mc -compress-debug-sections=zlib-gnu -filetype=obj -triple=x86_64-unknown-linux %s -o %t2
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# RUN: llvm-mc -compress-debug-sections=zlib-gnu -filetype=obj -triple=powerpc64-unknown-unknown %s -o %t2-be
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# RUN: llvm-readobj --sections %t2 | FileCheck -check-prefix=GNU %s
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# RUN: llvm-readobj --sections %t2-be | FileCheck -check-prefix=GNU %s
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# GNU: Section {
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# GNU: Index: 2
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# GNU: Name: .zdebug_str
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# GNU-NEXT: Type: SHT_PROGBITS
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# GNU-NEXT: Flags [
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# GNU-NEXT: SHF_MERGE (0x10)
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# GNU-NEXT: SHF_STRINGS (0x20)
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# GNU-NEXT: ]
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# GNU-NEXT: Address:
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# GNU-NEXT: Offset:
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# GNU-NEXT: Size:
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# GNU-NEXT: Link:
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# GNU-NEXT: Info:
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# GNU-NEXT: AddressAlignment: 1
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# GNU-NEXT: EntrySize: 1
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# GNU-NEXT: }
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# RUN: ld.lld --hash-style=sysv %t -o %t.so -shared
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# RUN: llvm-readobj --sections --section-data %t.so | FileCheck -check-prefix=DATA %s
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# RUN: ld.lld --hash-style=sysv %t-be -o %t-be.so -shared
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# RUN: llvm-readobj --sections --section-data %t-be.so | FileCheck -check-prefix=DATA %s
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# RUN: ld.lld --hash-style=sysv %t2 -o %t2.so -shared
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# RUN: llvm-readobj --sections --section-data %t2.so | FileCheck -check-prefix=DATA %s
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# RUN: ld.lld --hash-style=sysv %t2-be -o %t2-be.so -shared
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# RUN: llvm-readobj --sections --section-data %t2-be.so | FileCheck -check-prefix=DATA %s
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# DATA: Section {
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# DATA: Index: 6
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# DATA: Name: .debug_str
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@ -1,45 +0,0 @@
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# REQUIRES: x86, zlib
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# RUN: llvm-mc -compress-debug-sections=zlib-gnu -filetype=obj -triple=x86_64-unknown-linux %s -o %t1
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# RUN: llvm-readobj --sections %t1 | FileCheck -check-prefix=GNU %s
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# GNU: Name: .zdebug_str
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# RUN: ld.lld %t1 -o %t2 -r
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# RUN: llvm-readobj --sections --section-data %t2 | FileCheck %s
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## Check we uncompress section and remove ".z" prefix specific for zlib-gnu compression.
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# CHECK: Section {
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# CHECK: Index:
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# CHECK: Name: .debug_str
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# CHECK-NEXT: Type: SHT_PROGBITS
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# CHECK-NEXT: Flags [
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# CHECK-NEXT: SHF_MERGE
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# CHECK-NEXT: SHF_STRINGS
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# CHECK-NEXT: ]
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# CHECK-NEXT: Address:
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# CHECK-NEXT: Offset:
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# CHECK-NEXT: Size:
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# CHECK-NEXT: Link:
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# CHECK-NEXT: Info:
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# CHECK-NEXT: AddressAlignment: 1
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# CHECK-NEXT: EntrySize: 1
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# CHECK-NEXT: SectionData (
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# CHECK-NEXT: 0000: {{.*}} |unsigned int.cha|
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# CHECK-NEXT: 0010: {{.*}} |r.unsigned char.|
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# CHECK-NEXT: 0020: {{.*}} |short unsigned i|
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# CHECK-NEXT: 0030: {{.*}} |nt.long unsigned|
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# CHECK-NEXT: 0040: {{.*}} | int.|
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# CHECK-NEXT: )
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# CHECK-NEXT: }
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.section .debug_str,"MS",@progbits,1
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.LASF2:
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.string "short unsigned int"
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.LASF3:
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.string "unsigned int"
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.LASF0:
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.string "long unsigned int"
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.LASF8:
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.string "char"
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.LASF1:
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.string "unsigned char"
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@ -11,6 +11,4 @@
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# CHECK-NOT: Bar
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.section .debug_Foo,"",@progbits
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.section .zdebug_Bar,"",@progbits
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.ascii "ZLIB"
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.quad 0
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