(TSL_SET): backport from db3.

diff --git a/db2/mutex/alpha.gcc b/db2/mutex/alpha.gcc
index 247d04cf311530da7f076198e69dbb894ed68456..2358657c572deca1b84e4e855ace95d575014822 100644 (file)
--- a/db2/mutex/alpha.gcc
+++ b/db2/mutex/alpha.gcc
@@ -1,52 +1,24 @@
 /*
- * @(#)alpha.gcc       10.1 (Sleepycat) 4/12/97
- *
- * The code appearing below is taken from Richard L. Sites, ed.  "Alpha
- * Architecture Reference Manual", Digital Press, 1992, page 5-7 and 5-8.
- * There are 2 modifications:
- *
- * 1. The jump from blbs __r1,30f to !__r1, which is dictated by the way the
- * TSL_SET macro is used.  The code suggested in Sites includes the main loop
- * of the spin lock, whereas in this code the rest the loop is specified in C.
- * The generated code might be suboptimal if the compiler generates a forward
- * branch for the usual case in which the mutex is uncontested.
- *
- * 2. At label 20, Sites suggests including code for testing for an excessive
- * number of _processor_ lock conflicts.  (The seq_c instruction stores its
- * first argument provided that no other processor has written to a byte range
- * including its memory-location argument.)  Absent such checking the code
- * below could conceivably stall silently on a multiprocessor alpha, depending
- * on how often processor/processor conflicts occur in a particular byte range.
- *
- * Note that the mb ("memory-barrier") instruction in TSL_UNSET is critical to
- * correct operation in a multiprocessor alpha (as is, of course, the mb in
- * the TSL_SET macro).  Without the mb, changes to shared memory that occurred
- * inside the critical section (before the TSL_UNSET) might reach shared memory
- * _after_ the change of tsl to 0, thereby permitting another processor to see
- * an inconsistent view of the data protected by the mutex.
+ * @(#)alpha.gcc       11.1 (Sleepycat) 8/30/99
  *
  * For gcc/alpha, 0 is clear, 1 is set.
  */
-#define TSL_SET(tsl) ({                                                        \
+#ifdef __GNUC__
+#define        TSL_SET(tsl) ({                                                 \
        register tsl_t *__l = (tsl);                                    \
-       register tsl_t __r1, __r2;                                      \
-       __asm__ volatile("                                              \n\
-          10: ldq_l %0,(%2)                                            \n\
-              blbs  %0,30f                                             \n\
-              or    %0,1,%1                                            \n\
-              stq_c %1,(%2)                                            \n\
-              beq   %1,20f                                             \n\
-              mb                                                       \n\
-              br    30f                                                \n\
-          20: br    10b                                                \n\
-          30: "                                                        \
-         : "=&r" (__r1), "=&r" (__r2)                                  \
-         : "r" (__l));                                                 \
-       !__r1;                                                          \
+       int __r;                                                        \
+       asm volatile(                                                   \
+               "1:     ldl_l   %0,%1\n"                                \
+               "       blbs    %0,2f\n"                                \
+               "       mov     1,%0\n"                                 \
+               "       stl_c   %0,%1\n"                                \
+               "       bne     %0,1b\n"                                \
+               "       mb\n"                                           \
+               "2:"                                                    \
+               : "=&r"(__r), "=m"(*__l) : "m"(*__l) : "memory");       \
+       __r;                                                            \
 })
+#endif
 
-#define TSL_UNSET(tsl) ({                                              \
-       register tsl_t *__l = (tsl);                                    \
-       __asm__ volatile("mb; stq $31,(%0);" : : "r" (__l));            \
-})
+#define        TSL_UNSET(tsl)  (*(tsl) = 0)
 #define        TSL_INIT(tsl)   TSL_UNSET(tsl)