llvm-project/llvm/unittests/Transforms/IPO/CMakeLists.txt

set(LLVM_LINK_COMPONENTS
  Core
  Support
  IPO
  )

add_llvm_unittest(IPOTests
  LowerTypeTests.cpp
  WholeProgramDevirt.cpp
  )
Introduce bitset metadata format and bitset lowering pass. This patch introduces a new mechanism that allows IR modules to co-operatively build pointer sets corresponding to addresses within a given set of globals. One particular use case for this is to allow a C++ program to efficiently verify (at each call site) that a vtable pointer is in the set of valid vtable pointers for the class or its derived classes. One way of doing this is for a toolchain component to build, for each class, a bit set that maps to the memory region allocated for the vtables, such that each 1 bit in the bit set maps to a valid vtable for that class, and lay out the vtables next to each other, to minimize the total size of the bit sets. The patch introduces a metadata format for representing pointer sets, an '@llvm.bitset.test' intrinsic and an LTO lowering pass that lays out the globals and builds the bitsets, and documents the new feature. Differential Revision: http://reviews.llvm.org/D7288 llvm-svn: 230054 2015-02-21 04:30:47 +08:00			`set(LLVM_LINK_COMPONENTS`
			`Core`
			`Support`
			`IPO`
			`)`

			`add_llvm_unittest(IPOTests`
IR: New representation for CFI and virtual call optimization pass metadata. The bitset metadata currently used in LLVM has a few problems: 1. It has the wrong name. The name "bitset" refers to an implementation detail of one use of the metadata (i.e. its original use case, CFI). This makes it harder to understand, as the name makes no sense in the context of virtual call optimization. 2. It is represented using a global named metadata node, rather than being directly associated with a global. This makes it harder to manipulate the metadata when rebuilding global variables, summarise it as part of ThinLTO and drop unused metadata when associated globals are dropped. For this reason, CFI does not currently work correctly when both CFI and vcall opt are enabled, as vcall opt needs to rebuild vtable globals, and fails to associate metadata with the rebuilt globals. As I understand it, the same problem could also affect ASan, which rebuilds globals with a red zone. This patch solves both of those problems in the following way: 1. Rename the metadata to "type metadata". This new name reflects how the metadata is currently being used (i.e. to represent type information for CFI and vtable opt). The new name is reflected in the name for the associated intrinsic (llvm.type.test) and pass (LowerTypeTests). 2. Attach metadata directly to the globals that it pertains to, rather than using the "llvm.bitsets" global metadata node as we are doing now. This is done using the newly introduced capability to attach metadata to global variables (r271348 and r271358). See also: http://lists.llvm.org/pipermail/llvm-dev/2016-June/100462.html Differential Revision: http://reviews.llvm.org/D21053 llvm-svn: 273729 2016-06-25 05:21:32 +08:00			`LowerTypeTests.cpp`
WholeProgramDevirt: introduce. This pass implements whole program optimization of virtual calls in cases where we know (via bitset information) that the list of callees is fixed. This includes the following: - Single implementation devirtualization: if a virtual call has a single possible callee, replace all calls with a direct call to that callee. - Virtual constant propagation: if the virtual function's return type is an integer <=64 bits and all possible callees are readnone, for each class and each list of constant arguments: evaluate the function, store the return value alongside the virtual table, and rewrite each virtual call as a load from the virtual table. - Uniform return value optimization: if the conditions for virtual constant propagation hold and each function returns the same constant value, replace each virtual call with that constant. - Unique return value optimization for i1 return values: if the conditions for virtual constant propagation hold and a single vtable's function returns 0, or a single vtable's function returns 1, replace each virtual call with a comparison of the vptr against that vtable's address. Differential Revision: http://reviews.llvm.org/D16795 llvm-svn: 260312 2016-02-10 06:50:34 +08:00			`WholeProgramDevirt.cpp`
Introduce bitset metadata format and bitset lowering pass. This patch introduces a new mechanism that allows IR modules to co-operatively build pointer sets corresponding to addresses within a given set of globals. One particular use case for this is to allow a C++ program to efficiently verify (at each call site) that a vtable pointer is in the set of valid vtable pointers for the class or its derived classes. One way of doing this is for a toolchain component to build, for each class, a bit set that maps to the memory region allocated for the vtables, such that each 1 bit in the bit set maps to a valid vtable for that class, and lay out the vtables next to each other, to minimize the total size of the bit sets. The patch introduces a metadata format for representing pointer sets, an '@llvm.bitset.test' intrinsic and an LTO lowering pass that lays out the globals and builds the bitsets, and documents the new feature. Differential Revision: http://reviews.llvm.org/D7288 llvm-svn: 230054 2015-02-21 04:30:47 +08:00			`)`