[lld] r244934 - Template OutputSection only over Is64Bit.
Rafael Espindola via llvm-commits
llvm-commits at lists.llvm.org
Thu Aug 13 11:37:23 PDT 2015
Author: rafael
Date: Thu Aug 13 13:37:23 2015
New Revision: 244934
URL: http://llvm.org/viewvc/llvm-project?rev=244934&view=rev
Log:
Template OutputSection only over Is64Bit.
This is a bit more c++ code, but:
* It is less machine code: lld's text is 44688 bytes smaller.
* It should be a bit more efficient in the non native endian case.
* It should be a bit more efficient on architectures with slow unaligned access.
Modified:
lld/trunk/ELF/Writer.cpp
Modified: lld/trunk/ELF/Writer.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Writer.cpp?rev=244934&r1=244933&r2=244934&view=diff
==============================================================================
--- lld/trunk/ELF/Writer.cpp (original)
+++ lld/trunk/ELF/Writer.cpp Thu Aug 13 13:37:23 2015
@@ -32,14 +32,15 @@ namespace {
// Chunks cannot belong to more than one OutputSections. The writer
// creates multiple OutputSections and assign them unique,
// non-overlapping file offsets and VAs.
-template <class ELFT> class OutputSection {
+template <bool Is64Bits> class OutputSection {
public:
- typedef typename llvm::object::ELFFile<ELFT>::uintX_t uintX_t;
- typedef typename llvm::object::ELFFile<ELFT>::Elf_Shdr Elf_Shdr;
+ typedef typename std::conditional<Is64Bits, uint64_t, uint32_t>::type uintX_t;
+ typedef
+ typename std::conditional<Is64Bits, Elf64_Shdr, Elf32_Shdr>::type HeaderT;
OutputSection(StringRef Name, uint32_t sh_type, uintX_t sh_flags)
: Name(Name) {
- memset(&Header, 0, sizeof(Elf_Shdr));
+ memset(&Header, 0, sizeof(HeaderT));
Header.sh_type = sh_type;
Header.sh_flags = sh_flags;
}
@@ -47,7 +48,8 @@ public:
void setFileOffset(uintX_t Off) { Header.sh_offset = Off; }
void addChunk(Chunk *C);
std::vector<Chunk *> &getChunks() { return Chunks; }
- void writeHeaderTo(Elf_Shdr *SHdr);
+ template <endianness E>
+ void writeHeaderTo(typename ELFFile<ELFType<E, Is64Bits>>::Elf_Shdr *SHdr);
StringRef getName() { return Name; }
void setNameOffset(uintX_t Offset) { Header.sh_name = Offset; }
@@ -58,7 +60,7 @@ public:
private:
StringRef Name;
- Elf_Shdr Header;
+ HeaderT Header;
std::vector<Chunk *> Chunks;
};
@@ -79,8 +81,8 @@ private:
SymbolTable *Symtab;
std::unique_ptr<llvm::FileOutputBuffer> Buffer;
- llvm::SpecificBumpPtrAllocator<OutputSection<ELFT>> CAlloc;
- std::vector<OutputSection<ELFT> *> OutputSections;
+ llvm::SpecificBumpPtrAllocator<OutputSection<ELFT::Is64Bits>> CAlloc;
+ std::vector<OutputSection<ELFT::Is64Bits> *> OutputSections;
uintX_t FileSize;
uintX_t SizeOfHeaders;
@@ -118,7 +120,7 @@ template <class ELFT> void Writer<ELFT>:
error(Buffer->commit());
}
-template <class ELFT> void OutputSection<ELFT>::addChunk(Chunk *C) {
+template <bool Is64Bits> void OutputSection<Is64Bits>::addChunk(Chunk *C) {
Chunks.push_back(C);
uintX_t Off = Header.sh_size;
Off = RoundUpToAlignment(Off, C->getAlign());
@@ -127,8 +129,20 @@ template <class ELFT> void OutputSection
Header.sh_size = Off;
}
-template <class ELFT> void OutputSection<ELFT>::writeHeaderTo(Elf_Shdr *SHdr) {
- *SHdr = Header;
+template <bool Is64Bits>
+template <endianness E>
+void OutputSection<Is64Bits>::writeHeaderTo(
+ typename ELFFile<ELFType<E, Is64Bits>>::Elf_Shdr *SHdr) {
+ SHdr->sh_name = Header.sh_name;
+ SHdr->sh_type = Header.sh_type;
+ SHdr->sh_flags = Header.sh_flags;
+ SHdr->sh_addr = Header.sh_addr;
+ SHdr->sh_offset = Header.sh_offset;
+ SHdr->sh_size = Header.sh_size;
+ SHdr->sh_link = Header.sh_link;
+ SHdr->sh_info = Header.sh_info;
+ SHdr->sh_addralign = Header.sh_addralign;
+ SHdr->sh_entsize = Header.sh_entsize;
}
namespace {
@@ -161,17 +175,18 @@ template <bool Is64Bits> struct DenseMap
// Create output section objects and add them to OutputSections.
template <class ELFT> void Writer<ELFT>::createSections() {
- SmallDenseMap<SectionKey<ELFT::Is64Bits>, OutputSection<ELFT> *> Map;
+ SmallDenseMap<SectionKey<ELFT::Is64Bits>, OutputSection<ELFT::Is64Bits> *>
+ Map;
for (std::unique_ptr<ObjectFileBase> &FileB : Symtab->ObjectFiles) {
auto &File = cast<ObjectFile<ELFT>>(*FileB);
for (SectionChunk<ELFT> *C : File.getChunks()) {
const Elf_Shdr *H = C->getSectionHdr();
SectionKey<ELFT::Is64Bits> Key{C->getSectionName(), H->sh_type,
H->sh_flags};
- OutputSection<ELFT> *&Sec = Map[Key];
+ OutputSection<ELFT::Is64Bits> *&Sec = Map[Key];
if (!Sec) {
Sec = new (CAlloc.Allocate())
- OutputSection<ELFT>(Key.Name, Key.sh_type, Key.sh_flags);
+ OutputSection<ELFT::Is64Bits>(Key.Name, Key.sh_type, Key.sh_flags);
OutputSections.push_back(Sec);
}
Sec->addChunk(C);
@@ -179,8 +194,8 @@ template <class ELFT> void Writer<ELFT>:
}
}
-template <class ELFT>
-static bool compSec(OutputSection<ELFT> *A, OutputSection<ELFT> *B) {
+template <bool Is64Bits>
+static bool compSec(OutputSection<Is64Bits> *A, OutputSection<Is64Bits> *B) {
// Place SHF_ALLOC sections first.
return (A->getFlags() & SHF_ALLOC) && !(B->getFlags() & SHF_ALLOC);
}
@@ -192,9 +207,10 @@ template <class ELFT> void Writer<ELFT>:
uintX_t VA = 0x1000; // The first page is kept unmapped.
uintX_t FileOff = SizeOfHeaders;
- std::stable_sort(OutputSections.begin(), OutputSections.end(), compSec<ELFT>);
+ std::stable_sort(OutputSections.begin(), OutputSections.end(),
+ compSec<ELFT::Is64Bits>);
- for (OutputSection<ELFT> *Sec : OutputSections) {
+ for (OutputSection<ELFT::Is64Bits> *Sec : OutputSections) {
if (Sec->getFlags() & SHF_ALLOC) {
Sec->setVA(VA);
VA += RoundUpToAlignment(Sec->getSize(), PageSize);
@@ -267,9 +283,9 @@ template <class ELFT> void Writer<ELFT>:
auto SHdrs = reinterpret_cast<Elf_Shdr_Impl<ELFT> *>(Buf + EHdr->e_shoff);
// First entry is null.
++SHdrs;
- for (OutputSection<ELFT> *Sec : OutputSections) {
+ for (OutputSection<ELFT::Is64Bits> *Sec : OutputSections) {
Sec->setNameOffset(StrTabBuilder.getOffset(Sec->getName()));
- Sec->writeHeaderTo(SHdrs++);
+ Sec->template writeHeaderTo<ELFT::TargetEndianness>(SHdrs++);
}
// String table.
@@ -295,7 +311,7 @@ template <class ELFT> void Writer<ELFT>:
// Write section contents to a mmap'ed file.
template <class ELFT> void Writer<ELFT>::writeSections() {
uint8_t *Buf = Buffer->getBufferStart();
- for (OutputSection<ELFT> *Sec : OutputSections) {
+ for (OutputSection<ELFT::Is64Bits> *Sec : OutputSections) {
uint8_t *SecBuf = Buf + Sec->getOffset();
for (Chunk *C : Sec->getChunks())
C->writeTo(SecBuf);
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