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make ConstString allocate memory in non-tiny chunks 

BumpPtrAllocator allocates in 4KiB chunks, which with any larger
project is going to result in a large number of allocations.
Increasing allocation size this way can save 10%-20% of symbol
load time for a huge C++ project with correctly built debuginfo.

Differential Revision: https://reviews.llvm.org/D68549

llvm-svn: 374583
This commit is contained in:
Lubos Lunak 2019-10-11 19:34:39 +00:00
parent f358c3d371
commit e2ca7cb504
1 changed files with 7 additions and 2 deletions
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9
lldb/source/Utility/ConstString.cpp
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@ -31,7 +31,10 @@ using namespace lldb_private;
class Pool {
public:
typedef const char *StringPoolValueType;
typedef llvm::StringMap<StringPoolValueType, llvm::BumpPtrAllocator>
// BumpPtrAllocator allocates in 4KiB chunks, any larger C++ project is going
// to have megabytes of symbols, so allocate in larger chunks.
typedef llvm::BumpPtrAllocatorImpl<llvm::MallocAllocator, 1048576> Allocator;
typedef llvm::StringMap<StringPoolValueType, Allocator>
StringPool;
typedef llvm::StringMapEntry<StringPoolValueType> StringPoolEntryType;
@ -152,7 +155,9 @@ protected:
struct PoolEntry {
mutable llvm::sys::SmartRWMutex<false> m_mutex;
StringPool m_string_map;
// StringMap by default starts with 16 buckets, any larger project is
// going to have many symbols, so start with a larger value.
StringPool m_string_map = StringPool( 65536 );
};
std::array<PoolEntry, 256> m_string_pools;