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Diffstat (limited to 'qemu/disas/libvixl/vixl/compiler-intrinsics.cc')
| -rw-r--r-- | qemu/disas/libvixl/vixl/compiler-intrinsics.cc | 144 |
1 files changed, 144 insertions, 0 deletions
diff --git a/qemu/disas/libvixl/vixl/compiler-intrinsics.cc b/qemu/disas/libvixl/vixl/compiler-intrinsics.cc new file mode 100644 index 000000000..fd551faeb --- /dev/null +++ b/qemu/disas/libvixl/vixl/compiler-intrinsics.cc @@ -0,0 +1,144 @@ +// Copyright 2015, ARM Limited +// All rights reserved. +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are met: +// +// * Redistributions of source code must retain the above copyright notice, +// this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above copyright notice, +// this list of conditions and the following disclaimer in the documentation +// and/or other materials provided with the distribution. +// * Neither the name of ARM Limited nor the names of its contributors may be +// used to endorse or promote products derived from this software without +// specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS CONTRIBUTORS "AS IS" AND +// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED +// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE +// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE +// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR +// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER +// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, +// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +#include "compiler-intrinsics.h" + +namespace vixl { + + +int CountLeadingSignBitsFallBack(int64_t value, int width) { + VIXL_ASSERT(IsPowerOf2(width) && (width <= 64)); + if (value >= 0) { + return CountLeadingZeros(value, width) - 1; + } else { + return CountLeadingZeros(~value, width) - 1; + } +} + + +int CountLeadingZerosFallBack(uint64_t value, int width) { + VIXL_ASSERT(IsPowerOf2(width) && (width <= 64)); + if (value == 0) { + return width; + } + int count = 0; + value = value << (64 - width); + if ((value & UINT64_C(0xffffffff00000000)) == 0) { + count += 32; + value = value << 32; + } + if ((value & UINT64_C(0xffff000000000000)) == 0) { + count += 16; + value = value << 16; + } + if ((value & UINT64_C(0xff00000000000000)) == 0) { + count += 8; + value = value << 8; + } + if ((value & UINT64_C(0xf000000000000000)) == 0) { + count += 4; + value = value << 4; + } + if ((value & UINT64_C(0xc000000000000000)) == 0) { + count += 2; + value = value << 2; + } + if ((value & UINT64_C(0x8000000000000000)) == 0) { + count += 1; + } + count += (value == 0); + return count; +} + + +int CountSetBitsFallBack(uint64_t value, int width) { + VIXL_ASSERT(IsPowerOf2(width) && (width <= 64)); + + // Mask out unused bits to ensure that they are not counted. + value &= (UINT64_C(0xffffffffffffffff) >> (64 - width)); + + // Add up the set bits. + // The algorithm works by adding pairs of bit fields together iteratively, + // where the size of each bit field doubles each time. + // An example for an 8-bit value: + // Bits: h g f e d c b a + // \ | \ | \ | \ | + // value = h+g f+e d+c b+a + // \ | \ | + // value = h+g+f+e d+c+b+a + // \ | + // value = h+g+f+e+d+c+b+a + const uint64_t kMasks[] = { + UINT64_C(0x5555555555555555), + UINT64_C(0x3333333333333333), + UINT64_C(0x0f0f0f0f0f0f0f0f), + UINT64_C(0x00ff00ff00ff00ff), + UINT64_C(0x0000ffff0000ffff), + UINT64_C(0x00000000ffffffff), + }; + + for (unsigned i = 0; i < (sizeof(kMasks) / sizeof(kMasks[0])); i++) { + int shift = 1 << i; + value = ((value >> shift) & kMasks[i]) + (value & kMasks[i]); + } + + return static_cast<int>(value); +} + + +int CountTrailingZerosFallBack(uint64_t value, int width) { + VIXL_ASSERT(IsPowerOf2(width) && (width <= 64)); + int count = 0; + value = value << (64 - width); + if ((value & UINT64_C(0xffffffff)) == 0) { + count += 32; + value = value >> 32; + } + if ((value & 0xffff) == 0) { + count += 16; + value = value >> 16; + } + if ((value & 0xff) == 0) { + count += 8; + value = value >> 8; + } + if ((value & 0xf) == 0) { + count += 4; + value = value >> 4; + } + if ((value & 0x3) == 0) { + count += 2; + value = value >> 2; + } + if ((value & 0x1) == 0) { + count += 1; + } + count += (value == 0); + return count - (64 - width); +} + + +} // namespace vixl |