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[ARM] Use std::call_once for thread safe initialization 

Thanks to r234628 & r234631

llvm-svn: 234733
This commit is contained in:
Denis Protivensky 2015-04-13 10:18:21 +00:00
parent 8830b93fac
commit f40ef51feb
1 changed files with 18 additions and 20 deletions
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38
lld/lib/ReaderWriter/ELF/ARM/ARMTargetHandler.h
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@ -14,7 +14,6 @@
#include "ARMRelocationHandler.h"
#include "ELFReader.h"
#include "TargetLayout.h"
#include "llvm/ADT/Optional.h"
namespace lld {
namespace elf {
@ -25,24 +24,24 @@ public:
ARMTargetLayout(ARMLinkingContext &ctx) : TargetLayout<ELFT>(ctx) {}
uint64_t getGOTSymAddr() {
if (!_gotSymAddr.hasValue()) {
AtomLayout *gotAtom = this->findAbsoluteAtom("_GLOBAL_OFFSET_TABLE_");
_gotSymAddr = gotAtom ? gotAtom->_virtualAddr : 0;
}
return *_gotSymAddr;
std::call_once(_gotSymOnce, [this]() {
if (AtomLayout *gotAtom = this->findAbsoluteAtom("_GLOBAL_OFFSET_TABLE_"))
_gotSymAddr = gotAtom->_virtualAddr;
});
return _gotSymAddr;
}
uint64_t getTPOffset() {
if (_tpOff.hasValue())
return *_tpOff;
for (const auto &phdr : *this->_programHeader) {
if (phdr->p_type == llvm::ELF::PT_TLS) {
_tpOff = llvm::RoundUpToAlignment(TCB_SIZE, phdr->p_align);
return *_tpOff;
std::call_once(_tpOffOnce, [this]() {
for (const auto &phdr : *this->_programHeader) {
if (phdr->p_type == llvm::ELF::PT_TLS) {
_tpOff = llvm::RoundUpToAlignment(TCB_SIZE, phdr->p_align);
break;
}
}
}
llvm_unreachable("TLS segment not found");
assert(_tpOff != 0 && "TLS segment not found");
});
return _tpOff;
}
bool target1Rel() const { return this->_ctx.armTarget1Rel(); }
@ -52,11 +51,10 @@ private:
enum { TCB_SIZE = 0x8 };
private:
// Cached value of the GOT origin symbol address.
llvm::Optional<uint64_t> _gotSymAddr;
// Cached value of the TLS offset from the $tp pointer.
llvm::Optional<uint64_t> _tpOff;
uint64_t _gotSymAddr = 0;
uint64_t _tpOff = 0;
std::once_flag _gotSymOnce;
std::once_flag _tpOffOnce;
};
class ARMTargetHandler final : public TargetHandler {