[lld] r355622 - ELF: Reduce the size of InputSectionBase by two words. NFCI.
Peter Collingbourne via llvm-commits
llvm-commits at lists.llvm.org
Thu Mar 7 10:48:12 PST 2019
Author: pcc
Date: Thu Mar 7 10:48:12 2019
New Revision: 355622
URL: http://llvm.org/viewvc/llvm-project?rev=355622&view=rev
Log:
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
Modified:
lld/trunk/ELF/InputSection.h
Modified: lld/trunk/ELF/InputSection.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/InputSection.h?rev=355622&r1=355621&r2=355622&view=diff
==============================================================================
--- lld/trunk/ELF/InputSection.h (original)
+++ lld/trunk/ELF/InputSection.h Thu Mar 7 10:48:12 2019
@@ -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(
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