b3b81196aa
Now that we're using c++17, the type_traits with a ::value member have a _v alias which reduces verbosity. Or on other words std::is_integral<T>::value can be replaced with std::is_integral_v<T> Make this substitution throughout the code base. In places where gem5 introduced it's own similar templates, add a V alias, spelled differently to match gem5's internal style. gem5: :IsVarArgs<T>::value => gem5::IsVarArgsV<T> Change-Id: I1d84ffc4a236ad699471569e7916ec17fe5f109a Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/48604 Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br> Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu> Tested-by: kokoro <noreply+kokoro@google.com>
304 lines
8.7 KiB
C++
304 lines
8.7 KiB
C++
/*
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* Copyright (c) 2021 ARM Limited
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* All rights reserved
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*
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* The license below extends only to copyright in the software and shall
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* not be construed as granting a license to any other intellectual
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* property including but not limited to intellectual property relating
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* to a hardware implementation of the functionality of the software
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* licensed hereunder. You may use the software subject to the license
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* terms below provided that you ensure that this notice is replicated
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* unmodified and in its entirety in all distributions of the software,
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* modified or unmodified, in source code or in binary form.
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*
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* Copyright (c) 2001, 2003-2005 The Regents of The University of Michigan
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* All rights reserved.
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*
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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: 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 the copyright holders 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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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef __BASE_INTMATH_HH__
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#define __BASE_INTMATH_HH__
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#include <cassert>
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#include <cstdint>
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#include <type_traits>
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#include <utility>
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#include "base/bitfield.hh"
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namespace gem5
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{
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/**
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* @ingroup api_base_utils
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*/
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template <class T>
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static constexpr std::enable_if_t<std::is_integral_v<T>, int>
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floorLog2(T x)
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{
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assert(x > 0);
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// A guaranteed unsigned version of x.
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uint64_t ux = (typename std::make_unsigned<T>::type)x;
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int y = 0;
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constexpr auto ts = sizeof(T);
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if (ts >= 8 && (ux & 0xffffffff00000000ULL)) { y += 32; ux >>= 32; }
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if (ts >= 4 && (ux & 0x00000000ffff0000ULL)) { y += 16; ux >>= 16; }
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if (ts >= 2 && (ux & 0x000000000000ff00ULL)) { y += 8; ux >>= 8; }
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if (ux & 0x00000000000000f0ULL) { y += 4; ux >>= 4; }
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if (ux & 0x000000000000000cULL) { y += 2; ux >>= 2; }
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if (ux & 0x0000000000000002ULL) { y += 1; }
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return y;
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}
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/**
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* @ingroup api_base_utils
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*/
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template <class T>
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static constexpr int
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ceilLog2(const T& n)
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{
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assert(n > 0);
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if (n == 1)
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return 0;
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return floorLog2(n - (T)1) + 1;
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}
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/**
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* @ingroup api_base_utils
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*/
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template <class T>
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static constexpr bool
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isPowerOf2(const T& n)
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{
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// If n is non-zero, and subtracting one borrows all the way to the MSB
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// and flips all bits, then this is a power of 2.
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return n && !(n & (n - 1));
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}
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/**
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* @ingroup api_base_utils
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*/
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template <class T, class U>
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static constexpr T
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divCeil(const T& a, const U& b)
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{
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return (a + b - 1) / b;
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}
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/**
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* @ingroup api_base_utils
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*/
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template <typename T>
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static constexpr std::enable_if_t<sizeof(T) <= sizeof(uint32_t)>
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mulUnsigned(std::make_unsigned_t<T> &high, std::make_unsigned_t<T> &low,
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std::make_unsigned_t<T> val_a, std::make_unsigned_t<T> val_b)
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{
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uint64_t product = (uint64_t)val_a * (uint64_t)val_b;
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low = product;
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high = (product >> (sizeof(low) * 8));
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};
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/**
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* @ingroup api_base_utils
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*/
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template <typename T>
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static constexpr std::enable_if_t<sizeof(T) <= sizeof(uint32_t)>
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mulSigned(std::make_signed_t<T> &high, std::make_signed_t<T> &low,
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std::make_signed_t<T> val_a, std::make_signed_t<T> val_b)
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{
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uint64_t product = (int64_t)val_a * (int64_t)val_b;
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low = product;
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high = (product >> (sizeof(low) * 8));
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};
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/**
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* Multiply two values with place value p.
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*
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* (A * p + a) * (B * p + b) =
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* (A * B) * p^2 + (a * B + A * b) * p + (a * b)
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*
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* low result = (a * B + A * b) * p + (a * b)
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* high result = (A * B) + carry out from low result.
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*
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* As long as p is at most half the capacity of the underlying type, no
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* individual multiplication will overflow. We just have to carefully manage
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* carries to avoid losing any during the addition steps.
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*/
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template <typename T>
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static constexpr std::enable_if_t<sizeof(T) == sizeof(uint64_t)>
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mulUnsignedManual(std::make_unsigned_t<T> &high, std::make_unsigned_t<T> &low,
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std::make_unsigned_t<T> val_a, std::make_unsigned_t<T> val_b)
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{
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low = val_a * val_b;
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uint64_t A = (uint32_t)(val_a >> 32);
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uint64_t a = (uint32_t)val_a;
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uint64_t B = (uint32_t)(val_b >> 32);
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uint64_t b = (uint32_t)val_b;
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uint64_t c1 = 0, c2 = 0; // Carry between place values.
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uint64_t ab = a * b, Ab = A * b, aB = a * B, AB = A * B;
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c1 = (uint32_t)(ab >> 32);
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// Be careful to avoid overflow.
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c2 = (c1 >> 1) + (Ab >> 1) + (aB >> 1);
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c2 += ((c1 & 0x1) + (Ab & 0x1) + (aB & 0x1)) >> 1;
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c2 >>= 31;
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high = AB + c2;
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}
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/**
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* @ingroup api_base_utils
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*/
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template <typename T>
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static constexpr std::enable_if_t<sizeof(T) == sizeof(uint64_t)>
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mulUnsigned(std::make_unsigned_t<T> &high, std::make_unsigned_t<T> &low,
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std::make_unsigned_t<T> val_a, std::make_unsigned_t<T> val_b)
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{
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#ifdef __SIZEOF_INT128__
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__uint128_t val = (__uint128_t)val_a * (__uint128_t)val_b;
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low = val;
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high = (val >> 64);
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#else
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mulUnsignedManual<T>(high, low, val_a, val_b);
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#endif
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}
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template <typename T>
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static constexpr std::enable_if_t<sizeof(T) == sizeof(uint64_t)>
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mulSignedManual(std::make_signed_t<T> &high, std::make_signed_t<T> &low,
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std::make_signed_t<T> val_a, std::make_signed_t<T> val_b)
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{
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uint64_t u_high = 0, u_low = 0;
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mulUnsigned<T>(u_high, u_low, val_a, val_b);
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if (val_a < 0)
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u_high -= val_b;
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if (val_b < 0)
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u_high -= val_a;
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high = u_high;
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low = u_low;
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}
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/**
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* @ingroup api_base_utils
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*/
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template <typename T>
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static constexpr std::enable_if_t<sizeof(T) == sizeof(uint64_t)>
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mulSigned(std::make_signed_t<T> &high, std::make_signed_t<T> &low,
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std::make_signed_t<T> val_a, std::make_signed_t<T> val_b)
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{
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#ifdef __SIZEOF_INT128__
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__int128_t val = (__int128_t)val_a * (__int128_t)val_b;
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low = val;
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high = (val >> 64);
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#else
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mulSignedManual<T>(high, low, val_a, val_b);
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#endif
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}
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template <typename T>
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static constexpr std::pair<std::make_unsigned_t<T>, std::make_unsigned_t<T>>
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mulUnsigned(std::make_unsigned_t<T> val_a, std::make_unsigned_t<T> val_b)
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{
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std::make_unsigned_t<T> hi{}, low{};
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mulUnsigned<T>(hi, low, val_a, val_b);
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return {hi, low};
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};
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template <typename T>
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static constexpr std::pair<std::make_signed_t<T>, std::make_signed_t<T>>
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mulSigned(std::make_signed_t<T> val_a, std::make_signed_t<T> val_b)
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{
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std::make_signed_t<T> hi{}, low{};
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mulSigned<T>(hi, low, val_a, val_b);
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return {hi, low};
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};
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/**
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* This function is used to align addresses in memory.
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*
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* @param val is the address to be aligned.
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* @param align is the alignment. Can only be a power of 2.
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* @return The aligned address. The smallest number divisible
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* by @param align which is greater than or equal to @param val.
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*
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* @ingroup api_base_utils
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*/
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template <class T, class U>
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static constexpr T
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roundUp(const T& val, const U& align)
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{
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assert(isPowerOf2(align));
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T mask = (T)align - 1;
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return (val + mask) & ~mask;
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}
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/**
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* This function is used to align addresses in memory.
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*
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* @param val is the address to be aligned.
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* @param align is the alignment. Can only be a power of 2.
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* @return The aligned address. The biggest number divisible
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* by @param align which is less than or equal to @param val.
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*
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* @ingroup api_base_utils
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*/
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template <class T, class U>
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static constexpr T
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roundDown(const T& val, const U& align)
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{
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assert(isPowerOf2(align));
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T mask = (T)align - 1;
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return val & ~mask;
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}
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/**
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* Calculate the log2 of a power of 2 integer
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*
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* @param An input value
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* @return The base 2 log of value
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*
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* @ingroup api_base_utils
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*/
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static constexpr int
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log2i(int value)
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{
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assert(isPowerOf2(value) && value > 0);
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return ctz32(value);
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}
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} // namespace gem5
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#endif // __BASE_INTMATH_HH__
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