From 0bad3f625e18d1369f180ef7d3d19678a8aa7b17 Mon Sep 17 00:00:00 2001 From: Jonas Devlieghere Date: Thu, 21 Jun 2018 21:37:53 +0000 Subject: [PATCH] [dsymutil] Force mmap'ing of binaries After the recent refactoring that introduced parallel handling of different object, the binary holder became unique per object file. This defeats its optimization of caching archives, leading to an archive being opened for every binary it contains. This is obviously unfortunate and will need to be refactored soon. Luckily in practice, the impact of this is limited as most files are mmap'ed instead of memcopy'd. There's a caveat however: when the memory buffer requires a null terminator and it's a multiple of the page size, we allocate instead of mmap'ing. If this happens for a static archive, we end up with N copies of it in memory, where N is the number of objects in the archive, leading to exuberant memory usage. This provided a stopgap solution to ensure that all the files it loads are mmap in memory by removing the requirement for a terminating null byte. Differential revision: https://reviews.llvm.org/D48397 llvm-svn: 335293 --- llvm/tools/dsymutil/BinaryHolder.cpp | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/llvm/tools/dsymutil/BinaryHolder.cpp b/llvm/tools/dsymutil/BinaryHolder.cpp index 86af81d0ba07..356156a5ebf7 100644 --- a/llvm/tools/dsymutil/BinaryHolder.cpp +++ b/llvm/tools/dsymutil/BinaryHolder.cpp @@ -62,7 +62,7 @@ ErrorOr> BinaryHolder::GetMemoryBuffersForFile( // (either because the archive is not there anymore, or because the // archive doesn't contain the requested member), this will still // provide a sensible error message. - auto ErrOrFile = MemoryBuffer::getFileOrSTDIN(Filename); + auto ErrOrFile = MemoryBuffer::getFileOrSTDIN(Filename, -1, false); if (auto Err = ErrOrFile.getError()) return Err; @@ -136,7 +136,7 @@ BinaryHolder::MapArchiveAndGetMemberBuffers( StringRef Filename, sys::TimePoint Timestamp) { StringRef ArchiveFilename = Filename.substr(0, Filename.find('(')); - auto ErrOrBuff = MemoryBuffer::getFileOrSTDIN(ArchiveFilename); + auto ErrOrBuff = MemoryBuffer::getFileOrSTDIN(ArchiveFilename, -1, false); if (auto Err = ErrOrBuff.getError()) return Err;