`LZ4_memcpy()` uses `__builtin_memcpy()` to ensure that clang/gcc
can inline the `memcpy()` calls in freestanding mode.
This is necessary for decompressing the Linux Kernel with LZ4.
Without an analogous patch decompression ran at 77 MB/s, and with
the patch it ran at 884 MB/s.
Similar work in the kernel:
https://patchwork.kernel.org/patch/11351499/
UBsan (+clang-10) complains about doing pointer arithmetic (adding 0)
to a nullpointer.
This patch is tested with clang-10+ubsan
Define 0-argument functions like foo(void) instead of foo(), in order
to avoid a warning with -Wold-style-definition. This makes it easier
to embed lz4.c in projects that compile with -Werror
-Wold-style-definition.
when src ptr is in very low memory area (< 64K),
the virtual reference to data in dictionary
might end up in a very high memory address.
Since it's not a "real" memory address,
just a virtual one, to calculate distance,
it doesn't matter : only distance matters.
The assert was to restrictive.
Fixed.
by enabling the fast decoder path.
Visual requires a different set of macro constants to detect x86 / x64.
On my laptop, decoding speed on x64 went up from 3.12 to 3.45 GB/s.
32-bit is less impressive, though still favorable,
with speed increasing from 2.55 to 2.60 GB/s.
So both cases are now enabled.
Suggested by Bartosz Taudul (@wolfpld).
Support the -D command line option for running benchmarks. The
benchmark code was slightly restructured to factor out the calls
that need to be different for each benchmark scenario. Since there
are now 4 scenarios (all combinations of fast/HC and with/without
dictionary), the logic was getting somewhat convoluted otherwise.
This was done by extending the compressionParameters struct that
previously contained just a single function pointer. It now
contains 4 function pointers for init/reset/compress/cleanup,
with the related state. The functions get a pointer to the
structure as their first argument (inspired by C++), so that they
can access the state values in the struct.
Add missing lz4 project to the VS2017 solution.
The project was made from scratch rather than importing and updated to
match the VS2010 options.
Any new options not present in the old VS2010 project we pulled from
other console binaries in the solution.
Signed-off-by: David A Kondrad <dkondrad.mscs+patches@gmail.com>
The `lz4` project was excluded from being checked in for VS2017.
Add some fixups to explicitly allow this project directory.
Also add an exclusion for VS2017 binaries and VS `ipch` directories.
Signed-off-by: David A Kondrad <dkondrad.mscs+patches@gmail.com>
