bit_set: Use <bit> and concepts

src/common/bit_set.h

@@ -2,78 +2,14 @@
 
 #pragma once
 
+#include <bit>
 #include <cstddef>
-#ifdef _WIN32
-#include <intrin.h>
-#endif
 #include <initializer_list>
-#include <new>
 #include <type_traits>
 #include "common/common_types.h"
 
-// namespace avoids conflict with OS X Carbon; don't use BitSet<T> directly
 namespace Common {
 
-// Helper functions:
-
-#ifdef _MSC_VER
-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
-
 // 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:
@@ -93,9 +29,8 @@ static inline int LeastSignificantSetBit(u64 val) {
 // - Counting set bits using .Count() - see comment on that method.
 
 template <typename IntTy>
+    requires std::is_unsigned_v<IntTy>
 class BitSet {
-    static_assert(!std::is_signed_v<IntTy>, "BitSet should not be used with signed types");
-
 public:
     // A reference to a particular bit, returned from operator[].
     class Ref {
@@ -122,7 +57,7 @@ public:
         constexpr Iterator(IntTy val) : m_val(val) {}
         constexpr int operator*() {
             // This will never be called when m_val == 0, because that would be the end() iterator
-            return LeastSignificantSetBit(m_val);
+            return std::countr_zero(m_val);
         }
         constexpr Iterator& operator++() {
             // Unset least significant set bit
@@ -200,13 +135,8 @@ public:
     constexpr 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.
     constexpr u32 Count() const {
-        return CountSetBits(m_val);
+        return std::popcount(m_val);
     }
 
     constexpr Iterator begin() const {

src/core/hle/service/cecd/cecd.cpp

@@ -1,7 +1,7 @@
 // Copyright 2015 Citra Emulator Project
 // Licensed under GPLv2 or any later version
 // Refer to the license.txt file included.
-
+#pragma optimize("", off)
 #include <boost/serialization/shared_ptr.hpp>
 #include <boost/serialization/unique_ptr.hpp>
 #include <cryptopp/base64.h>