c8d52465f9
In the process of optimising our per cpu data code, I found a ppc64 compiler bug that has been around forever. Basically the current RELOC_HIDE can end up trashing r30. Details of the bug can be found at http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25572 This bug is present in all compilers before 4.1. It is masked by the fact that our current per cpu data code is inefficient and causes other loads that end up marking r30 as used. A workaround identified by Alan Modra is to use the =r asm constraint instead of =g. Signed-off-by: Anton Blanchard <anton@samba.org> [ Verified that this makes no real difference on x86[-64] */ Signed-off-by: Linus Torvalds <torvalds@osdl.org>
33 lines
1.1 KiB
C
33 lines
1.1 KiB
C
/* Never include this file directly. Include <linux/compiler.h> instead. */
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/*
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* Common definitions for all gcc versions go here.
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*/
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/* Optimization barrier */
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/* The "volatile" is due to gcc bugs */
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#define barrier() __asm__ __volatile__("": : :"memory")
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/* This macro obfuscates arithmetic on a variable address so that gcc
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shouldn't recognize the original var, and make assumptions about it */
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/*
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* Versions of the ppc64 compiler before 4.1 had a bug where use of
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* RELOC_HIDE could trash r30. The bug can be worked around by changing
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* the inline assembly constraint from =g to =r, in this particular
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* case either is valid.
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*/
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#define RELOC_HIDE(ptr, off) \
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({ unsigned long __ptr; \
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__asm__ ("" : "=r"(__ptr) : "0"(ptr)); \
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(typeof(ptr)) (__ptr + (off)); })
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#define inline inline __attribute__((always_inline))
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#define __inline__ __inline__ __attribute__((always_inline))
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#define __inline __inline __attribute__((always_inline))
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#define __deprecated __attribute__((deprecated))
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#define noinline __attribute__((noinline))
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#define __attribute_pure__ __attribute__((pure))
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#define __attribute_const__ __attribute__((__const__))
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