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ELF: Reduce the size of InputSectionBase by two words. NFCI. 

- The Assigned bit was previously taking a word on its own. Move
  it into the bit fields in SectionBase.
- NumRelocations and AreRelocsRela were previously also taking up
  a word despite only using half of it. Move them into the alignment gap
  after SectionBase's fields.

Differential Revision: https://reviews.llvm.org/D59044

llvm-svn: 355622
This commit is contained in:
Peter Collingbourne 2019-03-07 18:48:12 +00:00
parent c8955e2293
commit dfbb9a793e
1 changed files with 21 additions and 21 deletions
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42
lld/ELF/InputSection.h
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@ -51,13 +51,26 @@ public:
unsigned SectionKind : 3;
// The next two bit fields are only used by InputSectionBase, but we
// The next three bit fields are only used by InputSectionBase, but we
// put them here so the struct packs better.
// The garbage collector sets sections' Live bits.
// If GC is disabled, all sections are considered live by default.
unsigned Live : 1;
// True if this section has already been placed to a linker script
// output section. This is needed because, in a linker script, you
// can refer to the same section more than once. For example, in
// the following linker script,
//
// .foo : { *(.text) }
// .bar : { *(.text) }
//
// .foo takes all .text sections, and .bar becomes empty. To achieve
// this, we need to memorize whether a section has been placed or
// not for each input section.
unsigned Assigned : 1;
unsigned Bss : 1;
// Set for sections that should not be folded by ICF.
@ -87,8 +100,8 @@ protected:
uint64_t Entsize, uint64_t Alignment, uint32_t Type,
uint32_t Info, uint32_t Link)
: Name(Name), Repl(this), SectionKind(SectionKind), Live(false),
Bss(false), KeepUnique(false), Alignment(Alignment), Flags(Flags),
Entsize(Entsize), Type(Type), Link(Link), Info(Info) {}
Assigned(false), Bss(false), KeepUnique(false), Alignment(Alignment),
Flags(Flags), Entsize(Entsize), Type(Type), Link(Link), Info(Info) {}
};
// This corresponds to a section of an input file.
@ -105,6 +118,11 @@ public:
static bool classof(const SectionBase *S) { return S->kind() != Output; }
// Relocations that refer to this section.
unsigned NumRelocations : 31;
unsigned AreRelocsRela : 1;
const void *FirstRelocation = nullptr;
// The file which contains this section. Its dynamic type is always
// ObjFile<ELFT>, but in order to avoid ELFT, we use InputFile as
// its static type.
@ -122,30 +140,12 @@ public:
uint64_t getOffsetInFile() const;
// True if this section has already been placed to a linker script
// output section. This is needed because, in a linker script, you
// can refer to the same section more than once. For example, in
// the following linker script,
//
// .foo : { *(.text) }
// .bar : { *(.text) }
//
// .foo takes all .text sections, and .bar becomes empty. To achieve
// this, we need to memorize whether a section has been placed or
// not for each input section.
bool Assigned = false;
// Input sections are part of an output section. Special sections
// like .eh_frame and merge sections are first combined into a
// synthetic section that is then added to an output section. In all
// cases this points one level up.
SectionBase *Parent = nullptr;
// Relocations that refer to this section.
const void *FirstRelocation = nullptr;
unsigned NumRelocations : 31;
unsigned AreRelocsRela : 1;
template <class ELFT> ArrayRef<typename ELFT::Rel> rels() const {
assert(!AreRelocsRela);
return llvm::makeArrayRef(