d7b0c5794e
Initial support for ARM NEON on Cortex-A9 and A15 CPUs. All but ~10 tests
pass, and all examples compile and run correctly. Most of the examples
show a ~2x speedup on a single A15 core versus scalar code.
Current open issues/TODOs
- Code quality looks decent, but hasn't been carefully examined. Known
issues/opportunities for improvement include:
- fp32 vector divide is done as a series of scalar divides rather than
a vector divide (which I believe exists, but I may be mistaken.)
This is particularly harmful to examples/rt, which only runs ~1.5x
faster with ispc, likely due to long chains of scalar divides.
- The compiler isn't generating a vmin.f32 for e.g. the final scalar
min in reduce_min(); instead it's generating a compare and then a
select instruction (and similarly elsewhere).
- There are some additional FIXMEs in builtins/target-neon.ll that
include both a few pieces of missing functionality (e.g. rounding
doubles) as well as places that deserve attention for possible
code quality improvements.
- Currently only the "cortex-a9" and "cortex-15" CPU targets are
supported; LLVM supports many other ARM CPUs and ispc should provide
access to all of the ones that have NEON support (and aren't too
obscure.)
- ~5 of the reduce-* tests hit an assertion inside LLVM (unfortunately
only when the compiler runs on an ARM host, though).
- The Windows build hasn't been tested (though I've tried to update
ispc.vcxproj appropriately). It may just work, but will more likely
have various small issues.)
- Anything related to 64-bit ARM has seen no attention.
92 lines
3.0 KiB
C
92 lines
3.0 KiB
C
/*
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Copyright (c) 2010-2011, Intel Corporation
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are
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met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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* Neither the name of Intel Corporation nor the names of its
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contributors may be used to endorse or promote products derived from
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this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
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IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
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PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
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OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <stdint.h>
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#ifdef __arm__
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#include <sys/time.h>
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// There's no easy way to get a hardware clock counter on ARM, so instead
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// we'll pretend it's a 1GHz processor and then compute pretend cycles
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// based on elapsed time from gettimeofday().
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__inline__ uint64_t rdtsc() {
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static bool first = true;
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static struct timeval tv_start;
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if (first) {
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gettimeofday(&tv_start, NULL);
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first = false;
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return 0;
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}
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struct timeval tv;
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gettimeofday(&tv, NULL);
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tv.tv_sec -= tv_start.tv_sec;
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tv.tv_usec -= tv_start.tv_usec;
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return (1000000ull * tv.tv_sec + tv.tv_usec) * 1000ull;
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}
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#else // __arm__
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#ifdef WIN32
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#include <windows.h>
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#define rdtsc __rdtsc
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#else // WIN32
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__inline__ uint64_t rdtsc() {
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uint32_t low, high;
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#ifdef __x86_64
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__asm__ __volatile__ ("xorl %%eax,%%eax \n cpuid"
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::: "%rax", "%rbx", "%rcx", "%rdx" );
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#else
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__asm__ __volatile__ ("xorl %%eax,%%eax \n cpuid"
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::: "%eax", "%ebx", "%ecx", "%edx" );
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#endif
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__asm__ __volatile__ ("rdtsc" : "=a" (low), "=d" (high));
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return (uint64_t)high << 32 | low;
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}
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#endif // !WIN32
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#endif // !__arm__
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static uint64_t start, end;
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static inline void reset_and_start_timer()
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{
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start = rdtsc();
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}
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/* Returns the number of millions of elapsed processor cycles since the
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last reset_and_start_timer() call. */
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static inline double get_elapsed_mcycles()
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{
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end = rdtsc();
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return (end-start) / (1024. * 1024.);
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}
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