Reid Kleckner 73e1a13fdc [IR] De-virtualize ~Value to save a vptr ... Summary: Implements PR889 Removing the virtual table pointer from Value saves 1% of RSS when doing LTO of llc on Linux. The impact on time was positive, but too noisy to conclusively say that performance improved. Here is a link to the spreadsheet with the original data: https://docs.google.com/spreadsheets/d/1F4FHir0qYnV0MEp2sYYp_BuvnJgWlWPhWOwZ6LbW7W4/edit?usp=sharing This change makes it invalid to directly delete a Value, User, or Instruction pointer. Instead, such code can be rewritten to a null check and a call Value::deleteValue(). Value objects tend to have their lifetimes managed through iplist, so for the most part, this isn't a big deal. However, there are some places where LLVM deletes values, and those places had to be migrated to deleteValue. I have also created llvm::unique_value, which has a custom deleter, so it can be used in place of std::unique_ptr<Value>. I had to add the "DerivedUser" Deleter escape hatch for MemorySSA, which derives from User outside of lib/IR. Code in IR cannot include MemorySSA headers or call the MemoryAccess object destructors without introducing a circular dependency, so we need some level of indirection. Unfortunately, no class derived from User may have any virtual methods, because adding a virtual method would break User::getHungOffOperands(), which assumes that it can find the use list immediately prior to the User object. I've added a static_assert to the appropriate OperandTraits templates to help people avoid this trap. Reviewers: chandlerc, mehdi_amini, pete, dberlin, george.burgess.iv Reviewed By: chandlerc Subscribers: krytarowski, eraman, george.burgess.iv, mzolotukhin, Prazek, nlewycky, hans, inglorion, pcc, tejohnson, dberlin, llvm-commits Differential Revision: https://reviews.llvm.org/D31261 llvm-svn: 303362		2017-05-18 17:24:10 +00:00
..
CMakeLists.txt	modules: Add explicit dependency on intrinsics_gen	2015-06-16 00:44:12 +00:00
LLLexer.cpp	AMDGPU: Add AMDGPU_HS calling convention	2017-05-02 15:41:10 +00:00
LLLexer.h	Remove empty non-virtual destructors or mark them =default when non-public	2015-04-11 15:32:26 +00:00
LLParser.cpp	[IR] De-virtualize ~Value to save a vptr	2017-05-18 17:24:10 +00:00
LLParser.h	[IR] Add AttributeSet to hide AttributeSetNode* again, NFC	2017-04-12 00:38:00 +00:00
LLToken.h	AMDGPU: Add AMDGPU_HS calling convention	2017-05-02 15:41:10 +00:00
LLVMBuild.txt
Parser.cpp	[AsmParser] Expose an API to parse a string starting with a type.	2016-03-08 00:37:07 +00:00