of the proposed standard hashing interfaces (N3333), and to use
a modified and tuned version of the CityHash algorithm.
Some of the highlights of this change:
-- Significantly higher quality hashing algorithm with very well
distributed results, and extremely few collisions. Should be close to
a checksum for up to 64-bit keys. Very little clustering or clumping of
hash codes, to better distribute load on probed hash tables.
-- Built-in support for reserved values.
-- Simplified API that composes cleanly with other C++ idioms and APIs.
-- Better scaling performance as keys grow. This is the fastest
algorithm I've found and measured for moderately sized keys (such as
show up in some of the uniquing and folding use cases)
-- Support for enabling per-execution seeds to prevent table ordering
or other artifacts of hashing algorithms to impact the output of
LLVM. The seeding would make each run different and highlight these
problems during bootstrap.
This implementation was tested extensively using the SMHasher test
suite, and pased with flying colors, doing better than the original
CityHash algorithm even.
I've included a unittest, although it is somewhat minimal at the moment.
I've also added (or refactored into the proper location) type traits
necessary to implement this, and converted users of GeneralHash over.
My only immediate concerns with this implementation is the performance
of hashing small keys. I've already started working to improve this, and
will continue to do so. Currently, the only algorithms faster produce
lower quality results, but it is likely there is a better compromise
than the current one.
Many thanks to Jeffrey Yasskin who did most of the work on the N3333
paper, pair-programmed some of this code, and reviewed much of it. Many
thanks also go to Geoff Pike Pike and Jyrki Alakuijala, the original
authors of CityHash on which this is heavily based, and Austin Appleby
who created MurmurHash and the SMHasher test suite.
Also thanks to Nadav, Tobias, Howard, Jay, Nick, Ahmed, and Duncan for
all of the review comments! If there are further comments or concerns,
please let me know and I'll jump on 'em.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151822 91177308-0d34-0410-b5e6-96231b3b80d8
it with memcpy. This also fixes a problem on big-endian hosts, where
addUnaligned would return different results depending on the alignment
of the data.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151247 91177308-0d34-0410-b5e6-96231b3b80d8
Added array subscript to SparseSet for convenience.
Slight reorg to make it easier to manage the def/use sets.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151228 91177308-0d34-0410-b5e6-96231b3b80d8
chip in r139383, and the PSP components of the triple are really
annoying to parse. Let's leave this chapter behind. There is no reason
to expect LLVM to see a PSP-related triple these days, and so no
reasonable motivation to support them.
It might be reasonable to prune a few of the older MIPS triple forms in
general, but as those at least cause no burden on parsing (they aren't
both a chip and an OS!), I'm happy to leave them in for now.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151156 91177308-0d34-0410-b5e6-96231b3b80d8
For objects that can be identified by small unsigned keys, SparseSet
provides constant time clear() and fast deterministic iteration. Insert,
erase, and find operations are typically faster than hash tables.
SparseSet is useful for keeping information about physical registers,
virtual registers, or numbered basic blocks.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151110 91177308-0d34-0410-b5e6-96231b3b80d8
They're private static methods but we can just make them static
functions in the implementation. It makes the implementations a touch
more wordy, but takes another chunk out of the header file.
Also, take the opportunity to switch the names to the new coding
conventions.
No functionality changed here.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151047 91177308-0d34-0410-b5e6-96231b3b80d8
construction. Simplify its interface, implementation, and users
accordingly as there is no longer an 'uninitialized' state to check for.
Also, fixes a bug lurking in the interface as there was one method that
didn't correctly check for initialization.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151024 91177308-0d34-0410-b5e6-96231b3b80d8
Accomplished by moving the body of StringRef::edit_distance into
a separate function that accepts two ArrayRefs, and making
StringRef::edit_distance a wrapper around the new function.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150621 91177308-0d34-0410-b5e6-96231b3b80d8
- Use unsigned literals when the desired result is unsigned. This mostly allows unsigned/signed mismatch warnings to be less noisy even if they aren't on by default.
- Remove misplaced llvm_unreachable.
- Add static to a declaration of a function on MSVC x86 only.
- Change some instances of calling a static function through a variable to simply calling that function while removing the unused variable.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150364 91177308-0d34-0410-b5e6-96231b3b80d8
some architectures. These are useful for interacting with multiarch or
bi-arch GCC (or GCC-based) toolchains.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@149895 91177308-0d34-0410-b5e6-96231b3b80d8
convert at least one client over to use them. Subsequent patches both to
LLVM and Clang will try to convert more people over to a common set of
predicates.
This round of predicates is focused on OS-categorization predicates.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@149815 91177308-0d34-0410-b5e6-96231b3b80d8
This new function provides a way to get the Mac OS X version number from
either generic "darwin" triples of macosx triples.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@149438 91177308-0d34-0410-b5e6-96231b3b80d8
now that this handles the release / retain calls.
Adds a regression test for that bug (which is a compile-time
regression) and for the last two changes to the IntrusiveRefCntPtr,
especially tests for the memory leak due to copy construction of the
ref-counted object and ensuring that the traits are used for release /
retain calls.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@149411 91177308-0d34-0410-b5e6-96231b3b80d8
BitVector uses the native word size for its internal representation.
That doesn't work well for literal bit masks in source code.
This patch adds BitVector operations to efficiently apply literal bit
masks specified as arrays of uint32_t. Since each array entry always
holds exactly 32 bits, these portable bit masks can be source code
literals, probably produced by TableGen.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@148272 91177308-0d34-0410-b5e6-96231b3b80d8
