/*
- * mem.spin: Promela code to validate memory barriers with OOO memory.
+ * mem.spin: Promela code to validate memory barriers with out-of-order memory
+ * and out-of-order instruction scheduling.
+ *
+ * Algorithm verified :
+ *
+ * alpha = 0;
+ * beta = 0;
+ *
+ * Process A Process B
+ * alpha = 1; x = beta;
+ * wmb(); rmb();
+ * beta = 1; y = alpha;
+ *
+ * if x = 1, then y will = 1 when it is read.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
/* Promela validation variables. */
-#define NR_READERS 1
-#define NR_WRITERS 1
+/*
+ * Produced process control and data flow. Updated after each instruction to
+ * show which variables are ready. Using one-hot bit encoding per variable to
+ * save state space. Used as triggers to execute the instructions having those
+ * variables as input. Leaving bits active to inhibit instruction execution.
+ * Scheme used to make instruction disabling and automatic dependency fall-back
+ * automatic.
+ */
+
+#define CONSUME_TOKENS(state, bits, notbits) \
+ ((!(state & (notbits))) && (state & (bits)) == (bits))
+
+#define PRODUCE_TOKENS(state, bits) \
+ state = state | (bits);
+
+#define CLEAR_TOKENS(state, bits) \
+ state = state & ~(bits)
#define NR_PROCS 2
* both.
*/
-#define DECLARE_CACHED_VAR(type, x, v) \
- type mem_##x = v; \
- type cached_##x[NR_PROCS] = v; \
- bit cache_dirty_##x[NR_PROCS] = 0
+#define DECLARE_CACHED_VAR(type, x, v) \
+ type mem_##x = v; \
+ type cached_##x[NR_PROCS] = v; \
+ bit cache_dirty_##x[NR_PROCS] = 0;
#define IS_CACHE_DIRTY(x, id) (cache_dirty_##x[id])
-#define READ_CACHED_VAR(x) (cached_##x[get_pid()])
+#define READ_CACHED_VAR(x) \
+ (cached_##x[get_pid()])
-#define WRITE_CACHED_VAR(x, v) \
- atomic { \
+#define WRITE_CACHED_VAR(x, v) \
+ atomic { \
cached_##x[get_pid()] = v; \
cache_dirty_##x[get_pid()] = 1; \
}
skip \
fi;
-#define CACHE_READ_FROM_MEM(x, id) \
- if \
- :: !IS_CACHE_DIRTY(x, id) -> \
- cached_##x[id] = mem_##x;\
- :: else -> \
- skip \
+#define CACHE_READ_FROM_MEM(x, id) \
+ if \
+ :: !IS_CACHE_DIRTY(x, id) -> \
+ cached_##x[id] = mem_##x; \
+ :: else -> \
+ skip \
fi;
/*
* May update other caches if cache is dirty, or not.
*/
-#define RANDOM_CACHE_WRITE_TO_MEM(x, id)\
- if \
+#define RANDOM_CACHE_WRITE_TO_MEM(x, id) \
+ if \
:: 1 -> CACHE_WRITE_TO_MEM(x, id); \
- :: 1 -> skip \
+ :: 1 -> skip \
fi;
#define RANDOM_CACHE_READ_FROM_MEM(x, id)\
- if \
+ if \
:: 1 -> CACHE_READ_FROM_MEM(x, id); \
- :: 1 -> skip \
+ :: 1 -> skip \
fi;
+inline ooo_mem()
+{
+ atomic {
+ RANDOM_CACHE_WRITE_TO_MEM(alpha, get_pid());
+ RANDOM_CACHE_WRITE_TO_MEM(beta, get_pid());
+ RANDOM_CACHE_READ_FROM_MEM(alpha, get_pid());
+ RANDOM_CACHE_READ_FROM_MEM(beta, get_pid());
+ }
+}
+
+/* must consume all prior read tokens */
inline smp_rmb()
{
atomic {
+ /* todo : consume all read tokens .. ? */
CACHE_READ_FROM_MEM(alpha, get_pid());
CACHE_READ_FROM_MEM(beta, get_pid());
}
}
+/* must consume all prior write tokens */
inline smp_wmb()
{
atomic {
}
}
+/* sync_core() must consume all prior read and write tokens, including rmb/wmb
+ * tokens */
+
+/* must consume all prior read and write tokens */
inline smp_mb()
{
atomic {
smp_wmb();
+ /* sync_core() */
smp_rmb();
}
}
DECLARE_CACHED_VAR(byte, alpha, 0);
DECLARE_CACHED_VAR(byte, beta, 0);
-inline ooo_mem()
-{
- atomic {
- RANDOM_CACHE_WRITE_TO_MEM(alpha, get_pid());
- RANDOM_CACHE_WRITE_TO_MEM(beta, get_pid());
- RANDOM_CACHE_READ_FROM_MEM(alpha, get_pid());
- RANDOM_CACHE_READ_FROM_MEM(beta, get_pid());
- }
-}
-
/* value 2 is uninitialized */
byte read_one = 2;
byte read_two = 2;
+/*
+ * Bit encoding, proc_one_produced :
+ */
+
+#define P1_PROD_NONE (1 << 0)
+
+#define P1_READ_ONE (1 << 1)
+#define P1_RMB (1 << 2)
+#define P1_READ_TWO (1 << 3)
+
+/* Only need a single color. */
+byte proc_one_produced;
+
active proctype test_proc_one()
{
assert(get_pid() < NR_PROCS);
- ooo_mem();
- WRITE_CACHED_VAR(alpha, 1);
- ooo_mem();
-#ifndef NO_WMB
- smp_wmb();
- ooo_mem();
-#endif
-#ifndef NO_RMB
- smp_rmb();
- ooo_mem();
+ PRODUCE_TOKENS(proc_one_produced, P1_PROD_NONE);
+#ifdef NO_RMB
+ PRODUCE_TOKENS(proc_one_produced, P1_RMB);
#endif
- read_one = READ_CACHED_VAR(beta);
- ooo_mem();
- // test : [] (read_one == 0 -> read_two != 0)
- // test : [] (read_two == 0 -> read_one != 0)
- assert(!(read_one == 0 && read_two == 0));
+
+ do
+ :: CONSUME_TOKENS(proc_one_produced,
+ P1_PROD_NONE, P1_READ_ONE) ->
+ ooo_mem();
+ read_one = READ_CACHED_VAR(beta);
+ ooo_mem();
+ PRODUCE_TOKENS(proc_one_produced, P1_READ_ONE);
+ :: CONSUME_TOKENS(proc_one_produced,
+ P1_READ_ONE, P1_RMB) ->
+ smp_rmb();
+ PRODUCE_TOKENS(proc_one_produced, P1_RMB);
+ :: CONSUME_TOKENS(proc_one_produced,
+ P1_RMB, P1_READ_TWO) ->
+ ooo_mem();
+ read_two = READ_CACHED_VAR(alpha);
+ ooo_mem();
+ PRODUCE_TOKENS(proc_one_produced, P1_READ_TWO);
+ :: CONSUME_TOKENS(proc_one_produced,
+ P1_PROD_NONE | P1_READ_ONE | P1_RMB
+ | P1_READ_TWO, 0) ->
+ break;
+ od;
+
+ //CLEAR_TOKENS(proc_one_produced,
+ // P1_PROD_NONE | P1_READ_ONE | P1_RMB | P1_READ_TWO);
+
+ // test : [] (read_one == 1 -> read_two == 1)
+ assert(read_one != 1 || read_two == 1);
}
+
+/*
+ * Bit encoding, proc_two_produced :
+ */
+
+#define P2_PROD_NONE (1 << 0)
+
+#define P2_WRITE_ONE (1 << 1)
+#define P2_WMB (1 << 2)
+#define P2_WRITE_TWO (1 << 3)
+
+/* Only need a single color. */
+byte proc_two_produced;
+
active proctype test_proc_two()
{
assert(get_pid() < NR_PROCS);
- ooo_mem();
- WRITE_CACHED_VAR(beta, 1);
- ooo_mem();
-#ifndef NO_WMB
- smp_wmb();
- ooo_mem();
-#endif
-#ifndef NO_RMB
- smp_rmb();
- ooo_mem();
+ PRODUCE_TOKENS(proc_two_produced, P2_PROD_NONE);
+#ifdef NO_WMB
+ PRODUCE_TOKENS(proc_two_produced, P2_WMB);
#endif
- read_two = READ_CACHED_VAR(alpha);
- ooo_mem();
- // test : [] (read_one == 0 -> read_two != 0)
- // test : [] (read_two == 0 -> read_one != 0)
- assert(!(read_one == 0 && read_two == 0));
+
+ do
+ :: CONSUME_TOKENS(proc_two_produced,
+ P2_PROD_NONE, P2_WRITE_ONE) ->
+ ooo_mem();
+ WRITE_CACHED_VAR(alpha, 1);
+ ooo_mem();
+ PRODUCE_TOKENS(proc_two_produced, P2_WRITE_ONE);
+ :: CONSUME_TOKENS(proc_two_produced,
+ P2_WRITE_ONE, P2_WMB) ->
+ smp_wmb();
+ PRODUCE_TOKENS(proc_two_produced, P2_WMB);
+ :: CONSUME_TOKENS(proc_two_produced,
+ P2_WMB, P2_WRITE_TWO) ->
+ ooo_mem();
+ WRITE_CACHED_VAR(beta, 1);
+ ooo_mem();
+ PRODUCE_TOKENS(proc_two_produced, P2_WRITE_TWO);
+ :: CONSUME_TOKENS(proc_two_produced,
+ P2_PROD_NONE | P2_WRITE_ONE
+ | P2_WMB | P2_WRITE_TWO, 0) ->
+ break;
+ od;
+
+ //CLEAR_TOKENS(proc_two_produced,
+ // P2_PROD_NONE | P2_WRITE_ONE | P2_WMB | P2_WRITE_TWO);
}