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Postgres FD Implementation
Commit 10986774 authored by Tom Lane's avatar Tom Lane
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Adjust TAS assembly as per recent discussions: use "+m"(*lock) everywhere 

to reference the spinlock variable, and specify "memory" as a clobber
operand to be sure gcc does not try to keep shared-memory values in
registers across a spinlock acquisition.  Also tighten the S/390 asm
sequence, which was apparently written with only minimal study of the
gcc asm documentation.  I have personally tested i386, ia64, ppc, hppa,
and s390 variants --- there is some small chance that I broke the others,
but I doubt it.
parent c1d9dec3
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Showing with 79 additions and 101 deletions
src/include/storage/s_lock.h
View file @ 10986774
......@@ -66,7 +66,7 @@
* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/storage/s_lock.h,v 1.125 2004/01/03 05:47:44 tgl Exp $
* $PostgreSQL: pgsql/src/include/storage/s_lock.h,v 1.126 2004/06/19 23:02:32 tgl Exp $
*
*-------------------------------------------------------------------------
*/
......@@ -85,16 +85,26 @@
* Other compilers use __cpu or __cpu__ so we test for both in those cases.
*/
/*
* Standard gcc asm format is:
*
/*----------
* Standard gcc asm format (assuming "volatile slock_t *lock"):
__asm__ __volatile__(
" command \n"
" command \n"
" command \n"
: "=r"(_res) return value, in register
: "r"(lock) argument, 'lock pointer', in register
: "r0"); inline code uses this register
" instruction \n"
" instruction \n"
" instruction \n"
: "=r"(_res), "+m"(*lock) // return register, in/out lock value
: "r"(lock) // lock pointer, in input register
: "memory", "cc"); // show clobbered registers here
* The output-operands list (after first colon) should always include
* "+m"(*lock), whether or not the asm code actually refers to this
* operand directly. This ensures that gcc believes the value in the
* lock variable is used and set by the asm code. Also, the clobbers
* list (after third colon) should always include "memory"; this prevents
* gcc from thinking it can cache the values of shared-memory fields
* across the asm code. Add "cc" if your asm code changes the condition
* code register, and also list any temp registers the code uses.
*----------
*/
......@@ -117,8 +127,9 @@ tas(volatile slock_t *lock)
" lock \n"
" xchgb %0,%1 \n"
"1: \n"
: "=q"(_res), "=m"(*lock)
: "0"(_res));
: "+q"(_res), "+m"(*lock)
:
: "memory", "cc");
return (int) _res;
}
......@@ -128,8 +139,7 @@ static __inline__ void
spin_delay(void)
{
__asm__ __volatile__(
" rep; nop \n"
: : : "memory");
" rep; nop \n");
}
#endif /* __i386__ || __x86_64__ */
......@@ -150,10 +160,9 @@ tas(volatile slock_t *lock)
__asm__ __volatile__(
" xchg4 %0=%1,%2 \n"
: "=r"(ret), "=m"(*lock)
: "r"(1), "1"(*lock)
: "=r"(ret), "+m"(*lock)
: "r"(1)
: "memory");
return (int) ret;
}
......@@ -173,46 +182,18 @@ tas(volatile slock_t *lock)
register slock_t _res = 1;
__asm__ __volatile__(
" swpb %0, %0, [%3] \n"
: "=r"(_res), "=m"(*lock)
: "0"(_res), "r"(lock));
" swpb %0, %0, [%2] \n"
: "+r"(_res), "+m"(*lock)
: "r"(lock)
: "memory");
return (int) _res;
}
#endif /* __arm__ */
#if defined(__s390__) && !defined(__s390x__)
/* S/390 Linux */
#define HAS_TEST_AND_SET
typedef unsigned int slock_t;
#define TAS(lock) tas(lock)
static __inline__ int
tas(volatile slock_t *lock)
{
int _res;
__asm__ __volatile__(
" la 1,1 \n"
" l 2,%2 \n"
" slr 0,0 \n"
" cs 0,1,0(2) \n"
" lr %1,0 \n"
: "=m"(lock), "=d"(_res)
: "m"(lock)
: "0", "1", "2");
return (_res);
}
#endif /* __s390__ */
#if defined(__s390x__)
/* S/390x Linux (64-bit zSeries) */
#if defined(__s390__) || defined(__s390x__)
/* S/390 and S/390x Linux (32- and 64-bit zSeries) */
#define HAS_TEST_AND_SET
typedef unsigned int slock_t;
......@@ -222,22 +203,17 @@ typedef unsigned int slock_t;
static __inline__ int
tas(volatile slock_t *lock)
{
int _res;
int _res = 0;
__asm__ __volatile__(
" la 1,1 \n"
" lg 2,%2 \n"
" slr 0,0 \n"
" cs 0,1,0(2) \n"
" lr %1,0 \n"
: "=m"(lock), "=d"(_res)
: "m"(lock)
: "0", "1", "2");
return (_res);
" cs %0,%3,0(%2) \n"
: "+d"(_res), "+m"(*lock)
: "a"(lock), "d"(1)
: "memory", "cc");
return _res;
}
#endif /* __s390x__ */
#endif /* __s390__ || __s390x__ */
#if defined(__sparc__)
......@@ -250,12 +226,13 @@ typedef unsigned char slock_t;
static __inline__ int
tas(volatile slock_t *lock)
{
register slock_t _res = 1;
register slock_t _res;
__asm__ __volatile__(
" ldstub [%2], %0 \n"
: "=r"(_res), "=m"(*lock)
: "r"(lock));
: "=r"(_res), "+m"(*lock)
: "r"(lock)
: "memory");
return (int) _res;
}
......@@ -283,11 +260,11 @@ tas(volatile slock_t *lock)
int _res;
__asm__ __volatile__(
" lwarx %0,0,%2 \n"
" lwarx %0,0,%3 \n"
" cmpwi %0,0 \n"
" bne 1f \n"
" addi %0,%0,1 \n"
" stwcx. %0,0,%2 \n"
" stwcx. %0,0,%3 \n"
" beq 2f \n"
"1: li %1,1 \n"
" b 3f \n"
......@@ -296,10 +273,9 @@ tas(volatile slock_t *lock)
" li %1,0 \n"
"3: \n"
: "=&r" (_t), "=r" (_res)
: "r" (lock)
: "cc", "memory"
);
: "=&r"(_t), "=r"(_res), "+m"(*lock)
: "r"(lock)
: "memory", "cc");
return _res;
}
......@@ -330,10 +306,9 @@ tas(volatile slock_t *lock)
" clrl %0 \n"
" tas %1 \n"
" sne %0 \n"
: "=d"(rv), "=m"(*lock)
: "1"(*lock)
: "cc");
: "=d"(rv), "+m"(*lock)
:
: "memory", "cc");
return rv;
}
......@@ -357,13 +332,13 @@ tas(volatile slock_t *lock)
register int _res;
__asm__ __volatile__(
" movl $1, r0 \n"
" bbssi $0, (%1), 1f \n"
" clrl r0 \n"
"1: movl r0, %0 \n"
: "=r"(_res)
" movl $1, %0 \n"
" bbssi $0, (%2), 1f \n"
" clrl %0 \n"
"1: \n"
: "=&r"(_res), "+m"(*lock)
: "r"(lock)
: "r0");
: "memory");
return _res;
}
......@@ -383,9 +358,11 @@ tas(volatile slock_t *lock)
register int _res;
__asm__ __volatile__(
" sbitb 0, %0 \n"
" sfsd %1 \n"
: "=m"(*lock), "=r"(_res));
" sbitb 0, %1 \n"
" sfsd %0 \n"
: "=r"(_res), "+m"(*lock)
:
: "memory");
return _res;
}
......@@ -404,12 +381,6 @@ tas(volatile slock_t *lock)
typedef unsigned long slock_t;
#define TAS(lock) tas(lock)
#define S_UNLOCK(lock) \
do \
{\
__asm__ __volatile__ (" mb \n"); \
*((volatile slock_t *) (lock)) = 0; \
} while (0)
static __inline__ int
tas(volatile slock_t *lock)
......@@ -417,24 +388,30 @@ tas(volatile slock_t *lock)
register slock_t _res;
__asm__ __volatile__(
" ldq $0, %0 \n"
" ldq $0, %1 \n"
" bne $0, 2f \n"
" ldq_l %1, %0 \n"
" bne %1, 2f \n"
" ldq_l %0, %1 \n"
" bne %0, 2f \n"
" mov 1, $0 \n"
" stq_c $0, %0 \n"
" stq_c $0, %1 \n"
" beq $0, 2f \n"
" mb \n"
" br 3f \n"
"2: mov 1, %1 \n"
"2: mov 1, %0 \n"
"3: \n"
: "=m"(*lock), "=r"(_res)
: "=&r"(_res), "+m"(*lock)
:
: "0");
: "memory", "0");
return (int) _res;
}
#define S_UNLOCK(lock) \
do \
{\
__asm__ __volatile__ (" mb \n"); \
*((volatile slock_t *) (lock)) = 0; \
} while (0)
#endif /* __alpha || __alpha__ */
......@@ -540,8 +517,9 @@ tas(volatile slock_t *lock)
__asm__ __volatile__(
" ldcwx 0(0,%2),%0 \n"
: "=r"(lockval), "=m"(*lockword)
: "r"(lockword));
: "=r"(lockval), "+m"(*lockword)
: "r"(lockword)
: "memory");
return (lockval == 0);
}
......
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