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0e2686762f
These ones are irrelevant to the config but rather to the platform, and as such are better placed in compiler.h. Here we take the opportunity for declaring a few extra capabilities: - HA_UNALIGNED : CPU supports unaligned accesses - HA_UNALIGNED_LE : CPU supports unaligned accesses in little endian - HA_UNALIGNED_FAST : CPU supports fast unaligned accesses - HA_UNALIGNED_ATOMIC : CPU supports unaligned accesses in atomics This will help remove a number of #ifdefs with arch-specific statements.
187 lines
6.0 KiB
C
187 lines
6.0 KiB
C
/*
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* include/common/compiler.h
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* This files contains some compiler-specific settings.
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*
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* Copyright (C) 2000-2009 Willy Tarreau - w@1wt.eu
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation, version 2.1
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* exclusively.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef _COMMON_COMPILER_H
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#define _COMMON_COMPILER_H
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/*
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* Gcc before 3.0 needs [0] to declare a variable-size array
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*/
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#ifndef VAR_ARRAY
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#if __GNUC__ < 3
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#define VAR_ARRAY 0
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#else
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#define VAR_ARRAY
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#endif
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#endif
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/* Support passing function parameters in registers. For this, the
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* CONFIG_REGPARM macro has to be set to the maximal number of registers
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* allowed. Some functions have intentionally received a regparm lower than
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* their parameter count, it is in order to avoid register clobbering where
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* they are called.
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*/
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#ifndef REGPRM1
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#if CONFIG_REGPARM >= 1 && __GNUC__ >= 3
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#define REGPRM1 __attribute__((regparm(1)))
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#else
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#define REGPRM1
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#endif
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#endif
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#ifndef REGPRM2
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#if CONFIG_REGPARM >= 2 && __GNUC__ >= 3
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#define REGPRM2 __attribute__((regparm(2)))
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#else
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#define REGPRM2 REGPRM1
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#endif
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#endif
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#ifndef REGPRM3
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#if CONFIG_REGPARM >= 3 && __GNUC__ >= 3
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#define REGPRM3 __attribute__((regparm(3)))
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#else
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#define REGPRM3 REGPRM2
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#endif
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#endif
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/* By default, gcc does not inline large chunks of code, but we want it to
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* respect our choices.
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*/
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#if !defined(forceinline)
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#if __GNUC__ < 3
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#define forceinline inline
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#else
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#define forceinline inline __attribute__((always_inline))
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#endif
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#endif
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/* silence the "unused" warnings without having to place painful #ifdefs.
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* For use with variables or functions.
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*/
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#define __maybe_unused __attribute__((unused))
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/* This allows gcc to know that some locations are never reached, for example
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* after a longjmp() in the Lua code, hence that some errors caught by such
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* methods cannot propagate further. This is important with gcc versions 6 and
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* above which can more aggressively detect null dereferences. The builtin
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* below was introduced in gcc 4.5, and before it we didn't care.
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*/
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#if __GNUC__ >= 5 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)
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#define my_unreachable() __builtin_unreachable()
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#else
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#define my_unreachable()
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#endif
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/* This macro may be used to block constant propagation that lets the compiler
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* detect a possible NULL dereference on a variable resulting from an explicit
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* assignment in an impossible check. Sometimes a function is called which does
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* safety checks and returns NULL if safe conditions are not met. The place
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* where it's called cannot hit this condition and dereferencing the pointer
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* without first checking it will make the compiler emit a warning about a
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* "potential null pointer dereference" which is hard to work around. This
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* macro "washes" the pointer and prevents the compiler from emitting tests
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* branching to undefined instructions. It may only be used when the developer
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* is absolutely certain that the conditions are guaranteed and that the
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* pointer passed in argument cannot be NULL by design.
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*/
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#define ALREADY_CHECKED(p) do { asm("" : "=rm"(p) : "0"(p)); } while (0)
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/*
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* Gcc >= 3 provides the ability for the programme to give hints to the
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* compiler about what branch of an if is most likely to be taken. This
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* helps the compiler produce the most compact critical paths, which is
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* generally better for the cache and to reduce the number of jumps.
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*/
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#if !defined(likely)
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#if __GNUC__ < 3
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#define __builtin_expect(x,y) (x)
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#define likely(x) (x)
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#define unlikely(x) (x)
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#elif __GNUC__ < 4 || __GNUC__ >= 5
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/* gcc 3.x and 5.x do the best job at this */
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#define likely(x) (__builtin_expect((x) != 0, 1))
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#define unlikely(x) (__builtin_expect((x) != 0, 0))
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#else
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/* GCC 4.x is stupid, it performs the comparison then compares it to 1,
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* so we cheat in a dirty way to prevent it from doing this. This will
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* only work with ints and booleans though.
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*/
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#define likely(x) (x)
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#define unlikely(x) (__builtin_expect((unsigned long)(x), 0))
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#endif
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#endif
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#ifndef __GNUC_PREREQ__
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#if defined(__GNUC__) && !defined(__INTEL_COMPILER)
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#define __GNUC_PREREQ__(ma, mi) \
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(__GNUC__ > (ma) || __GNUC__ == (ma) && __GNUC_MINOR__ >= (mi))
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#else
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#define __GNUC_PREREQ__(ma, mi) 0
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#endif
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#endif
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#ifndef offsetof
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#if __GNUC_PREREQ__(4, 1)
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#define offsetof(type, field) __builtin_offsetof(type, field)
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#else
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#define offsetof(type, field) \
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((size_t)(uintptr_t)((const volatile void *)&((type *)0)->field))
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#endif
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#endif
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/* Some architectures have a double-word CAS, sometimes even dual-8 bytes.
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* Some architectures support unaligned accesses, others are fine with them
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* but only for non-atomic operations. Also mention those supporting unaligned
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* accesses and being little endian, and those where unaligned accesses are
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* known to be fast (almost as fast as aligned ones).
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*/
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#if defined(__x86_64__)
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#define HA_UNALIGNED
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#define HA_UNALIGNED_LE
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#define HA_UNALIGNED_LE64
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#define HA_UNALIGNED_FAST
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#define HA_UNALIGNED_ATOMIC
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#define HA_HAVE_CAS_DW
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#define HA_CAS_IS_8B
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#elif defined(__i386__) || defined(__i486__) || defined(__i586__) || defined(__i686__)
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#define HA_UNALIGNED
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#define HA_UNALIGNED_LE
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#define HA_UNALIGNED_ATOMIC
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#elif defined (__aarch64__) || defined(__ARM_ARCH_8A)
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#define HA_UNALIGNED
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#define HA_UNALIGNED_LE
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#define HA_UNALIGNED_LE64
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#define HA_UNALIGNED_FAST
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#define HA_HAVE_CAS_DW
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#define HA_CAS_IS_8B
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#elif defined(__arm__) && (defined(__ARM_ARCH_7__) || defined(__ARM_ARCH_7A__))
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#define HA_UNALIGNED
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#define HA_UNALIGNED_LE
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#define HA_UNALIGNED_FAST
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#define HA_HAVE_CAS_DW
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#endif
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#endif /* _COMMON_COMPILER_H */
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