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| author | Peter Collingbourne <peter@pcc.me.uk> | 2015-02-20 20:30:47 +0000 |
|---|---|---|
| committer | Peter Collingbourne <peter@pcc.me.uk> | 2015-02-20 20:30:47 +0000 |
| commit | e6909c8e8ba07acb5e6366186fe186c91054e93c (patch) | |
| tree | 0e1f875c39059aa76d8ae64ba80136585d610aa0 /llvm/docs/index.rst | |
| parent | 0365675522ae4c7b754989d86c177875a52baa72 (diff) | |
| download | bcm5719-llvm-e6909c8e8ba07acb5e6366186fe186c91054e93c.tar.gz bcm5719-llvm-e6909c8e8ba07acb5e6366186fe186c91054e93c.zip | |
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
Diffstat (limited to 'llvm/docs/index.rst')
| -rw-r--r-- | llvm/docs/index.rst | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/llvm/docs/index.rst b/llvm/docs/index.rst index 65857cd170e..56567db32f6 100644 --- a/llvm/docs/index.rst +++ b/llvm/docs/index.rst @@ -244,6 +244,7 @@ For API clients and LLVM developers. CoverageMappingFormat Statepoints MergeFunctions + BitSets :doc:`WritingAnLLVMPass` Information on how to write LLVM transformations and analyses. |
