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-rw-r--r--include/llvm/MC/MCContext.h2
-rw-r--r--include/llvm/MC/MCSectionELF.h3
-rw-r--r--lib/MC/ELFObjectWriter.cpp44
-rw-r--r--lib/MC/MCContext.cpp16
-rw-r--r--test/MC/ELF/compression.s16
5 files changed, 48 insertions, 33 deletions
diff --git a/include/llvm/MC/MCContext.h b/include/llvm/MC/MCContext.h
index 07e0ab62942..98dd127c0c0 100644
--- a/include/llvm/MC/MCContext.h
+++ b/include/llvm/MC/MCContext.h
@@ -385,6 +385,8 @@ namespace llvm {
const MCSymbolELF *Group,
const MCSectionELF *Associated);
+ void renameELFSection(MCSectionELF *Section, StringRef Name);
+
MCSectionELF *createELFGroupSection(const MCSymbolELF *Group);
MCSectionCOFF *getCOFFSection(StringRef Section, unsigned Characteristics,
diff --git a/include/llvm/MC/MCSectionELF.h b/include/llvm/MC/MCSectionELF.h
index a4a20a31b09..b3bb3ad4e02 100644
--- a/include/llvm/MC/MCSectionELF.h
+++ b/include/llvm/MC/MCSectionELF.h
@@ -62,6 +62,8 @@ private:
Group->setIsSignature();
}
+ void setSectionName(StringRef Name) { SectionName = Name; }
+
public:
~MCSectionELF();
@@ -73,7 +75,6 @@ public:
unsigned getType() const { return Type; }
unsigned getFlags() const { return Flags; }
unsigned getEntrySize() const { return EntrySize; }
- void setFlags(unsigned F) { Flags = F; }
const MCSymbolELF *getGroup() const { return Group; }
void PrintSwitchToSection(const MCAsmInfo &MAI, raw_ostream &OS,
diff --git a/lib/MC/ELFObjectWriter.cpp b/lib/MC/ELFObjectWriter.cpp
index 7250806167f..900dcf51a26 100644
--- a/lib/MC/ELFObjectWriter.cpp
+++ b/lib/MC/ELFObjectWriter.cpp
@@ -979,6 +979,26 @@ ELFObjectWriter::createRelocationSection(MCContext &Ctx,
return RelaSection;
}
+// Include the debug info compression header:
+// "ZLIB" followed by 8 bytes representing the uncompressed size of the section,
+// useful for consumers to preallocate a buffer to decompress into.
+static bool
+prependCompressionHeader(uint64_t Size,
+ SmallVectorImpl<char> &CompressedContents) {
+ const StringRef Magic = "ZLIB";
+ if (Size <= Magic.size() + sizeof(Size) + CompressedContents.size())
+ return false;
+ if (sys::IsLittleEndianHost)
+ sys::swapByteOrder(Size);
+ CompressedContents.insert(CompressedContents.begin(),
+ Magic.size() + sizeof(Size), 0);
+ std::copy(Magic.begin(), Magic.end(), CompressedContents.begin());
+ std::copy(reinterpret_cast<char *>(&Size),
+ reinterpret_cast<char *>(&Size + 1),
+ CompressedContents.begin() + Magic.size());
+ return true;
+}
+
void ELFObjectWriter::writeSectionData(const MCAssembler &Asm, MCSection &Sec,
const MCAsmLayout &Layout) {
MCSectionELF &Section = static_cast<MCSectionELF &>(Sec);
@@ -1009,30 +1029,12 @@ void ELFObjectWriter::writeSectionData(const MCAssembler &Asm, MCSection &Sec,
return;
}
- uint64_t HdrSize =
- is64Bit() ? sizeof(ELF::Elf32_Chdr) : sizeof(ELF::Elf64_Chdr);
- if (UncompressedData.size() <= HdrSize + CompressedContents.size()) {
+ if (!prependCompressionHeader(UncompressedData.size(), CompressedContents)) {
getStream() << UncompressedData;
return;
}
-
- // Set the compressed flag. That is zlib style.
- Section.setFlags(Section.getFlags() | ELF::SHF_COMPRESSED);
-
- // Platform specific header is followed by compressed data.
- if (is64Bit()) {
- // Write Elf64_Chdr header.
- write(static_cast<ELF::Elf64_Word>(ELF::ELFCOMPRESS_ZLIB));
- write(static_cast<ELF::Elf64_Word>(0)); // ch_reserved field.
- write(static_cast<ELF::Elf64_Xword>(UncompressedData.size()));
- write(static_cast<ELF::Elf64_Xword>(Sec.getAlignment()));
- } else {
- // Write Elf32_Chdr header otherwise.
- write(static_cast<ELF::Elf32_Word>(ELF::ELFCOMPRESS_ZLIB));
- write(static_cast<ELF::Elf32_Word>(UncompressedData.size()));
- write(static_cast<ELF::Elf32_Word>(Sec.getAlignment()));
- }
-
+ Asm.getContext().renameELFSection(&Section,
+ (".z" + SectionName.drop_front(1)).str());
getStream() << CompressedContents;
}
diff --git a/lib/MC/MCContext.cpp b/lib/MC/MCContext.cpp
index aa15ff69904..67463e583d7 100644
--- a/lib/MC/MCContext.cpp
+++ b/lib/MC/MCContext.cpp
@@ -285,6 +285,22 @@ MCSectionMachO *MCContext::getMachOSection(StringRef Segment, StringRef Section,
Segment, Section, TypeAndAttributes, Reserved2, Kind, Begin);
}
+void MCContext::renameELFSection(MCSectionELF *Section, StringRef Name) {
+ StringRef GroupName;
+ if (const MCSymbol *Group = Section->getGroup())
+ GroupName = Group->getName();
+
+ unsigned UniqueID = Section->getUniqueID();
+ ELFUniquingMap.erase(
+ ELFSectionKey{Section->getSectionName(), GroupName, UniqueID});
+ auto I = ELFUniquingMap.insert(std::make_pair(
+ ELFSectionKey{Name, GroupName, UniqueID},
+ Section))
+ .first;
+ StringRef CachedName = I->first.SectionName;
+ const_cast<MCSectionELF *>(Section)->setSectionName(CachedName);
+}
+
MCSectionELF *MCContext::createELFRelSection(StringRef Name, unsigned Type,
unsigned Flags, unsigned EntrySize,
const MCSymbolELF *Group,
diff --git a/test/MC/ELF/compression.s b/test/MC/ELF/compression.s
index edee6f878f0..5560ba78c68 100644
--- a/test/MC/ELF/compression.s
+++ b/test/MC/ELF/compression.s
@@ -3,19 +3,13 @@
// RUN: llvm-dwarfdump -debug-dump=info %t | FileCheck --check-prefix=INFO %s
// RUN: llvm-mc -filetype=obj -compress-debug-sections -triple i386-pc-linux-gnu < %s \
// RUN: | llvm-readobj -symbols - | FileCheck --check-prefix=386-SYMBOLS %s
-// RUN: llvm-readobj -sections %t | FileCheck --check-prefix=ZLIB %s
// REQUIRES: zlib
-// Check that debug_line section was not renamed, so it is
-// zlib-style, not zlib-gnu one. Check that SHF_COMPRESSED was set.
-// ZLIB: Section {
-// ZLIB: Index:
-// ZLIB: Name: .debug_line
-// ZLIB-NEXT: Type: SHT_PROGBITS
-// ZLIB-NEXT: Flags [
-// ZLIB-NEXT: SHF_COMPRESSED
-// ZLIB-NEXT: ]
+// CHECK: Contents of section .zdebug_line:
+// Check for the 'ZLIB' file magic at the start of the section only
+// CHECK-NEXT: ZLIB
+// CHECK-NOT: ZLIB
// Don't compress small sections, such as this simple debug_abbrev example
// CHECK: Contents of section .debug_abbrev:
@@ -36,7 +30,7 @@
// sections, so make sure we handle symbols inside compressed sections
// 386-SYMBOLS: Name: .Linfo_string0
// 386-SYMBOLS-NOT: }
-// 386-SYMBOLS: Section: .debug_str
+// 386-SYMBOLS: Section: .zdebug_str
.section .debug_line,"",@progbits
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-21 21:52:44 +0000