mimalloc/include/mimalloc/bits.h
2024-12-09 14:31:43 -08:00

306 lines
11 KiB
C

/* ----------------------------------------------------------------------------
Copyright (c) 2019-2024 Microsoft Research, Daan Leijen
This is free software; you can redistribute it and/or modify it under the
terms of the MIT license. A copy of the license can be found in the file
"LICENSE" at the root of this distribution.
-----------------------------------------------------------------------------*/
/* ----------------------------------------------------------------------------
Bit operation, and platform dependent definition (MI_INTPTR_SIZE etc)
---------------------------------------------------------------------------- */
#pragma once
#ifndef MI_BITS_H
#define MI_BITS_H
// ------------------------------------------------------
// Size of a pointer.
// We assume that `sizeof(void*)==sizeof(intptr_t)`
// and it holds for all platforms we know of.
//
// However, the C standard only requires that:
// p == (void*)((intptr_t)p))
// but we also need:
// i == (intptr_t)((void*)i)
// or otherwise one might define an intptr_t type that is larger than a pointer...
// ------------------------------------------------------
#if INTPTR_MAX > INT64_MAX
# define MI_INTPTR_SHIFT (4) // assume 128-bit (as on arm CHERI for example)
#elif INTPTR_MAX == INT64_MAX
# define MI_INTPTR_SHIFT (3)
#elif INTPTR_MAX == INT32_MAX
# define MI_INTPTR_SHIFT (2)
#else
#error platform pointers must be 32, 64, or 128 bits
#endif
#if (INTPTR_MAX) > LONG_MAX
# define MI_PU(x) x##ULL
#else
# define MI_PU(x) x##UL
#endif
#if SIZE_MAX == UINT64_MAX
# define MI_SIZE_SHIFT (3)
typedef int64_t mi_ssize_t;
#elif SIZE_MAX == UINT32_MAX
# define MI_SIZE_SHIFT (2)
typedef int32_t mi_ssize_t;
#else
#error platform objects must be 32 or 64 bits in size
#endif
#if (SIZE_MAX/2) > LONG_MAX
# define MI_ZU(x) x##ULL
#else
# define MI_ZU(x) x##UL
#endif
#define MI_INTPTR_SIZE (1<<MI_INTPTR_SHIFT)
#define MI_INTPTR_BITS (MI_INTPTR_SIZE*8)
#define MI_SIZE_SIZE (1<<MI_SIZE_SHIFT)
#define MI_SIZE_BITS (MI_SIZE_SIZE*8)
#define MI_KiB (MI_ZU(1024))
#define MI_MiB (MI_KiB*MI_KiB)
#define MI_GiB (MI_MiB*MI_KiB)
/* --------------------------------------------------------------------------------
Architecture
-------------------------------------------------------------------------------- */
#if defined(__amd64__) || defined(__amd64) || defined(__x86_64__) || defined(__x86_64) || defined(_M_X64) || defined(_M_AMD64)
#define MI_ARCH_X64 1
#elif defined(__i386__) || defined(__i386) || defined(_M_IX86) || defined(_X86_) || defined(__X86__)
#define MI_ARCH_X86 1
#elif defined(__aarch64__) || defined(_M_ARM64) || defined(_M_HYBRID_X86_ARM64) || defined(_M_ARM64EC)
#define MI_ARCH_ARM64 1
#elif defined(__arm__) || defined(_ARM) || defined(_M_ARM) || defined(_M_ARMT) || defined(__arm)
#define MI_ARCH_ARM32 1
#elif defined(__riscv) || defined(_M_RISCV)
#define MI_ARCH_RISCV 1
#if (LONG_MAX == INT32_MAX)
#define MI_ARCH_RISCV32 1
#else
#define MI_ARCH_RISCV64 1
#endif
#endif
#if MI_ARCH_X64 && defined(__AVX2__)
#include <immintrin.h>
#endif
#if defined(_MSC_VER) && (MI_ARCH_X64 || MI_ARCH_X86 || MI_ARCH_ARM64 || MI_ARCH_ARM32)
#include <intrin.h>
#endif
#if defined(__AVX2__) && !defined(__BMI2__) // msvc
#define __BMI2__ 1
#endif
#if (defined(__AVX2__) || defined(__BMI2__)) && !defined(__BMI1__) // msvc
#define __BMI1__ 1
#endif
// Define big endian if needed
// #define MI_BIG_ENDIAN 1
/* --------------------------------------------------------------------------------
Builtin's
-------------------------------------------------------------------------------- */
#ifndef __has_builtin
#define __has_builtin(x) 0
#endif
#define mi_builtin(name) __builtin_##name
#define mi_has_builtin(name) __has_builtin(__builtin_##name)
#if (LONG_MAX == INT32_MAX)
#define mi_builtin32(name) mi_builtin(name##l)
#define mi_has_builtin32(name) mi_has_builtin(name##l)
#else
#define mi_builtin32(name) mi_builtin(name)
#define mi_has_builtin32(name) mi_has_builtin(name)
#endif
#if (LONG_MAX == INT64_MAX)
#define mi_builtin64(name) mi_builtin(name##l)
#define mi_has_builtin64(name) mi_has_builtin(name##l)
#else
#define mi_builtin64(name) mi_builtin(name##ll)
#define mi_has_builtin64(name) mi_has_builtin(name##ll)
#endif
#if (MI_SIZE_BITS == 32)
#define mi_builtinz(name) mi_builtin32(name)
#define mi_has_builtinz(name) mi_has_builtin32(name)
#define mi_msc_builtinz(name) name
#elif (MI_SIZE_BITS == 64)
#define mi_builtinz(name) mi_builtin64(name)
#define mi_has_builtinz(name) mi_has_builtin64(name)
#define mi_msc_builtinz(name) name##64
#endif
/* --------------------------------------------------------------------------------
Count trailing/leading zero's
-------------------------------------------------------------------------------- */
size_t _mi_clz_generic(size_t x);
size_t _mi_ctz_generic(size_t x);
static inline size_t mi_ctz(size_t x) {
#if defined(__GNUC__) && MI_ARCH_X64 && defined(__BMI1__) // on x64 tzcnt is defined for 0
uint64_t r;
__asm ("tzcnt\t%1, %0" : "=&r"(r) : "r"(x) : "cc");
return r;
#elif MI_ARCH_X64 && defined(__BMI1__)
return (size_t)_tzcnt_u64(x);
#elif defined(_MSC_VER) && (MI_ARCH_X64 || MI_ARCH_X86 || MI_ARCH_ARM64 || MI_ARCH_ARM32)
unsigned long idx;
return (mi_msc_builtinz(_BitScanForward)(&idx, x) ? (size_t)idx : MI_SIZE_BITS);
#elif mi_has_builtinz(ctz)
return (x!=0 ? (size_t)mi_builtinz(ctz)(x) : MI_SIZE_BITS);
#else
#define MI_HAS_FAST_BITSCAN 0
return (x!=0 ? _mi_ctz_generic(x) : MI_SIZE_BITS);
#endif
}
static inline size_t mi_clz(size_t x) {
#if defined(__GNUC__) && MI_ARCH_X64 && defined(__BMI1__) // on x64 lzcnt is defined for 0
uint64_t r;
__asm ("lzcnt\t%1, %0" : "=&r"(r) : "r"(x) : "cc");
return r;
#elif MI_ARCH_X64 && defined(__BMI1__)
return (size_t)_lzcnt_u64(x);
#elif defined(_MSC_VER) && (MI_ARCH_X64 || MI_ARCH_X86 || MI_ARCH_ARM64 || MI_ARCH_ARM32)
unsigned long idx;
return (mi_msc_builtinz(_BitScanReverse)(&idx, x) ? MI_SIZE_BITS - 1 - (size_t)idx : MI_SIZE_BITS);
#elif mi_has_builtinz(clz)
return (x!=0 ? (size_t)mi_builtinz(clz)(x) : MI_SIZE_BITS);
#else
#define MI_HAS_FAST_BITSCAN 0
return (x!=0 ? _mi_clz_generic(x) : MI_SIZE_BITS);
#endif
}
#ifndef MI_HAS_FAST_BITSCAN
#define MI_HAS_FAST_BITSCAN 1
#endif
size_t _mi_popcount_generic(size_t x);
static inline size_t mi_popcount(size_t x) {
#if mi_has_builtinz(popcount)
return mi_builtinz(popcount)(x);
#elif defined(_MSC_VER) && (MI_ARCH_X64 || MI_ARCH_X86 || MI_ARCH_ARM64 || MI_ARCH_ARM32)
return mi_msc_builtinz(__popcnt)(x);
#elif MI_ARCH_X64 && defined(__BMI1__)
return (size_t)_mm_popcnt_u64(x);
#else
#define MI_HAS_FAST_POPCOUNT 0
return (x<=1 ? x : _mi_popcount_generic(x));
#endif
}
#ifndef MI_HAS_FAST_POPCOUNT
#define MI_HAS_FAST_POPCOUNT 1
#endif
/* --------------------------------------------------------------------------------
find trailing/leading zero (bit scan forward/reverse)
-------------------------------------------------------------------------------- */
// Bit scan forward: find the least significant bit that is set (i.e. count trailing zero's)
// return false if `x==0` (with `*idx` undefined) and true otherwise,
// with the `idx` is set to the bit index (`0 <= *idx < MI_BFIELD_BITS`).
static inline bool mi_bsf(size_t x, size_t* idx) {
#if defined(__GNUC__) && MI_ARCH_X64 && defined(__BMI1__)
// on x64 the carry flag is set on zero which gives better codegen
bool is_zero;
__asm ( "tzcnt\t%2, %1" : "=@ccc"(is_zero), "=r"(*idx) : "r"(x) : "cc" );
return !is_zero;
#elif defined(_MSC_VER) && (MI_ARCH_X64 || MI_ARCH_X86 || MI_ARCH_ARM64 || MI_ARCH_ARM32)
unsigned long i;
return (mi_msc_builtinz(_BitScanForward)(&i, x) ? (*idx = (size_t)i, true) : false);
#else
return (x!=0 ? (*idx = mi_ctz(x), true) : false);
#endif
}
// Bit scan reverse: find the most significant bit that is set
// return false if `x==0` (with `*idx` undefined) and true otherwise,
// with the `idx` is set to the bit index (`0 <= *idx < MI_BFIELD_BITS`).
static inline bool mi_bsr(size_t x, size_t* idx) {
#if defined(__GNUC__) && MI_ARCH_X64 && defined(__BMI1__)
// on x64 the carry flag is set on zero which gives better codegen
bool is_zero;
__asm ("lzcnt\t%2, %1" : "=@ccc"(is_zero), "=r"(*idx) : "r"(x) : "cc");
return !is_zero;
#elif defined(_MSC_VER) && (MI_ARCH_X64 || MI_ARCH_X86 || MI_ARCH_ARM64 || MI_ARCH_ARM32)
unsigned long i;
return (mi_msc_builtinz(_BitScanReverse)(&i, x) ? (*idx = (size_t)i, true) : false);
#else
return (x!=0 ? (*idx = MI_SIZE_BITS - 1 - mi_clz(x), true) : false);
#endif
}
/* --------------------------------------------------------------------------------
rotate
-------------------------------------------------------------------------------- */
static inline size_t mi_rotr(size_t x, size_t r) {
#if (mi_has_builtin(rotateright64) && MI_SIZE_BITS==64)
return mi_builtin(rotateright64)(x,r);
#elif (mi_has_builtin(rotateright32) && MI_SIZE_BITS==32)
return mi_builtin(rotateright32)(x,r);
#elif defined(_MSC_VER) && (MI_ARCH_X64 || MI_ARCH_ARM64)
return _rotr64(x, (int)r);
#elif defined(_MSC_VER) && (MI_ARCH_X86 || MI_ARCH_ARM32)
return _lrotr(x,(int)r);
#else
// The term `(-rshift)&(BITS-1)` is written instead of `BITS - rshift` to
// avoid UB when `rshift==0`. See <https://blog.regehr.org/archives/1063>
const unsigned int rshift = (unsigned int)(r) & (MI_SIZE_BITS-1);
return ((x >> rshift) | (x << ((-rshift) & (MI_SIZE_BITS-1))));
#endif
}
static inline size_t mi_rotl(size_t x, size_t r) {
#if (mi_has_builtin(rotateleft64) && MI_SIZE_BITS==64)
return mi_builtin(rotateleft64)(x,r);
#elif (mi_has_builtin(rotateleft32) && MI_SIZE_BITS==32)
return mi_builtin(rotateleft32)(x,r);
#elif defined(_MSC_VER) && (MI_ARCH_X64 || MI_ARCH_ARM64)
return _rotl64(x, (int)r);
#elif defined(_MSC_VER) && (MI_ARCH_X86 || MI_ARCH_ARM32)
return _lrotl(x, (int)r);
#else
// The term `(-rshift)&(BITS-1)` is written instead of `BITS - rshift` to
// avoid UB when `rshift==0`. See <https://blog.regehr.org/archives/1063>
const unsigned int rshift = (unsigned int)(r) & (MI_SIZE_BITS-1);
return ((x << rshift) | (x >> ((-rshift) & (MI_SIZE_BITS-1))));
#endif
}
static inline uint32_t mi_rotl32(uint32_t x, uint32_t r) {
#if mi_has_builtin(rotateleft32)
return mi_builtin(rotateleft32)(x,r);
#elif defined(_MSC_VER) && (MI_ARCH_X64 || MI_ARCH_X86 || MI_ARCH_ARM64 || MI_ARCH_ARM32)
return _lrotl(x, (int)r);
#else
// The term `(-rshift)&(BITS-1)` is written instead of `BITS - rshift` to
// avoid UB when `rshift==0`. See <https://blog.regehr.org/archives/1063>
const unsigned int rshift = (unsigned int)(r) & 31;
return ((x << rshift) | (x >> ((-rshift) & 31)));
#endif
}
#endif // MI_BITS_H