dolphin/Source/Core/Common/BitSet.h
Fiora 8237004448 JIT: optimize for the common case of unquantized psq_l/st
Optimistically assume used GQRs are 0 in blocks that only use one GQR, and
bail at the start of the block and recompile if that assumption fails.

Many games use almost entirely unquantized stores (e.g. Rebel Strike, Sonic
Colors), so this will likely be a big performance improvement across the board
for games with heavy use of paired singles.
2015-01-10 14:14:43 -08:00

186 lines
5.8 KiB
C++

// This file is under the public domain.
#pragma once
#include <cstddef>
#include <initializer_list>
#include <type_traits>
#include "CommonTypes.h"
// Helper functions:
#ifdef _WIN32
template <typename T>
static inline int CountSetBits(T v)
{
// from https://graphics.stanford.edu/~seander/bithacks.html
// GCC has this built in, but MSVC's intrinsic will only emit the actual
// POPCNT instruction, which we're not depending on
v = v - ((v >> 1) & (T)~(T)0/3);
v = (v & (T)~(T)0/15*3) + ((v >> 2) & (T)~(T)0/15*3);
v = (v + (v >> 4)) & (T)~(T)0/255*15;
return (T)(v * ((T)~(T)0/255)) >> (sizeof(T) - 1) * 8;
}
static inline int LeastSignificantSetBit(u8 val)
{
unsigned long index;
_BitScanForward(&index, val);
return (int)index;
}
static inline int LeastSignificantSetBit(u16 val)
{
unsigned long index;
_BitScanForward(&index, val);
return (int)index;
}
static inline int LeastSignificantSetBit(u32 val)
{
unsigned long index;
_BitScanForward(&index, val);
return (int)index;
}
static inline int LeastSignificantSetBit(u64 val)
{
unsigned long index;
_BitScanForward64(&index, val);
return (int)index;
}
#else
static inline int CountSetBits(u8 val) { return __builtin_popcount(val); }
static inline int CountSetBits(u16 val) { return __builtin_popcount(val); }
static inline int CountSetBits(u32 val) { return __builtin_popcount(val); }
static inline int CountSetBits(u64 val) { return __builtin_popcountll(val); }
static inline int LeastSignificantSetBit(u8 val) { return __builtin_ctz(val); }
static inline int LeastSignificantSetBit(u16 val) { return __builtin_ctz(val); }
static inline int LeastSignificantSetBit(u32 val) { return __builtin_ctz(val); }
static inline int LeastSignificantSetBit(u64 val) { return __builtin_ctzll(val); }
#endif
// namespace avoids conflict with OS X Carbon; don't use BitSet<T> directly
namespace BS
{
// Similar to std::bitset, this is a class which encapsulates a bitset, i.e.
// using the set bits of an integer to represent a set of integers. Like that
// class, it acts like an array of bools:
// BitSet32 bs;
// bs[1] = true;
// but also like the underlying integer ([0] = least significant bit):
// BitSet32 bs2 = ...;
// bs = (bs ^ bs2) & BitSet32(0xffff);
// The following additional functionality is provided:
// - Construction using an initializer list.
// BitSet bs { 1, 2, 4, 8 };
// - Efficiently iterating through the set bits:
// for (int i : bs)
// [i is the *index* of a set bit]
// (This uses the appropriate CPU instruction to find the next set bit in one
// operation.)
// - Counting set bits using .Count() - see comment on that method.
// TODO: use constexpr when MSVC gets out of the Dark Ages
template <typename IntTy>
class BitSet
{
static_assert(!std::is_signed<IntTy>::value, "BitSet should not be used with signed types");
public:
// A reference to a particular bit, returned from operator[].
class Ref
{
public:
Ref(Ref&& other) : m_bs(other.m_bs), m_mask(other.m_mask) {}
Ref(BitSet* bs, IntTy mask) : m_bs(bs), m_mask(mask) {}
operator bool() const { return (m_bs->m_val & m_mask) != 0; }
bool operator=(bool set)
{
m_bs->m_val = (m_bs->m_val & ~m_mask) | (set ? m_mask : 0);
return set;
}
private:
BitSet* m_bs;
IntTy m_mask;
};
// A STL-like iterator is required to be able to use range-based for loops.
class Iterator
{
public:
Iterator(const Iterator& other) : m_val(other.m_val), m_bit(other.m_bit) {}
Iterator(IntTy val, int bit) : m_val(val), m_bit(bit) {}
Iterator& operator=(Iterator other) { new (this) Iterator(other); return *this; }
int operator*() { return m_bit; }
Iterator& operator++()
{
if (m_val == 0)
{
m_bit = -1;
}
else
{
int bit = LeastSignificantSetBit(m_val);
m_val &= ~(1 << bit);
m_bit = bit;
}
return *this;
}
Iterator operator++(int _)
{
Iterator other(*this);
++*this;
return other;
}
bool operator==(Iterator other) const { return m_bit == other.m_bit; }
bool operator!=(Iterator other) const { return m_bit != other.m_bit; }
private:
IntTy m_val;
int m_bit;
};
BitSet() : m_val(0) {}
explicit BitSet(IntTy val) : m_val(val) {}
BitSet(std::initializer_list<int> init)
{
m_val = 0;
for (int bit : init)
m_val |= (IntTy)1 << bit;
}
static BitSet AllTrue(size_t count)
{
return BitSet(count == sizeof(IntTy)*8 ? ~(IntTy)0 : (((IntTy)1 << count) - 1));
}
Ref operator[](size_t bit) { return Ref(this, (IntTy)1 << bit); }
const Ref operator[](size_t bit) const { return (*const_cast<BitSet*>(this))[bit]; }
bool operator==(BitSet other) const { return m_val == other.m_val; }
bool operator!=(BitSet other) const { return m_val != other.m_val; }
BitSet operator|(BitSet other) const { return BitSet(m_val | other.m_val); }
BitSet operator&(BitSet other) const { return BitSet(m_val & other.m_val); }
BitSet operator^(BitSet other) const { return BitSet(m_val ^ other.m_val); }
BitSet operator~() const { return BitSet(~m_val); }
BitSet& operator|=(BitSet other) { return *this = *this | other; }
BitSet& operator&=(BitSet other) { return *this = *this & other; }
BitSet& operator^=(BitSet other) { return *this = *this ^ other; }
operator u32() = delete;
operator bool() { return m_val != 0; }
// Warning: Even though on modern CPUs this is a single fast instruction,
// Dolphin's official builds do not currently assume POPCNT support on x86,
// so slower explicit bit twiddling is generated. Still should generally
// be faster than a loop.
unsigned int Count() const { return CountSetBits(m_val); }
Iterator begin() const { Iterator it(m_val, 0); return ++it; }
Iterator end() const { return Iterator(m_val, -1); }
IntTy m_val;
};
}
typedef BS::BitSet<u8> BitSet8;
typedef BS::BitSet<u16> BitSet16;
typedef BS::BitSet<u32> BitSet32;
typedef BS::BitSet<u64> BitSet64;