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fix locking for futures on uniprocessors

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The scheme_is_multiprocessor() function wasn't the right guard
for whether to use a locking compare-and-swap instruction; any
use of pthread-based futures needs the compare-and-swap.

Merge to v5.3.1
This commit is contained in:
Matthew Flatt 2012-11-02 12:56:09 -06:00 committed by Matthew Flatt
parent 1f0508d77e
commit 55170581c4
5 changed files with 13 additions and 18 deletions
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19
src/racket/src/future.c
View File

@ -156,7 +156,7 @@ static Scheme_Object *processor_count(int argc, Scheme_Object *argv[])
return scheme_make_integer(1);
}
int scheme_is_multiprocessor(int now)
int scheme_is_multithreaded(int now)
{
return 0;
}
@ -2195,17 +2195,14 @@ static void init_cpucount(void)
#endif
}
int scheme_is_multiprocessor(int now)
int scheme_is_multithreaded(int now)
{
if (cpucount > 1) {
if (!now)
return 1;
else {
Scheme_Future_State *fs = scheme_future_state;
return (fs && fs->future_threads_created);
}
} else
return 0;
if (!now)
return 1;
else {
Scheme_Future_State *fs = scheme_future_state;
return (fs && fs->future_threads_created);
}
}
Scheme_Object *processor_count(int argc, Scheme_Object *argv[])

4
src/racket/src/hash.c
View File

@ -61,8 +61,6 @@ static void register_traversers(void);
running in a future and setting flags on pairs. */
SHARED_OK static uintptr_t keygen;
XFORM_NONGCING extern int scheme_is_multiprocessor();
XFORM_NONGCING static MZ_INLINE
uintptr_t PTR_TO_LONG(Scheme_Object *o)
{
@ -92,7 +90,7 @@ uintptr_t PTR_TO_LONG(Scheme_Object *o)
#endif
if (!v) v = 0x1AD0;
#ifdef MZ_USE_FUTURES
if (SCHEME_PAIRP(o) && scheme_is_multiprocessor(1)) {
if (SCHEME_PAIRP(o) && scheme_is_multithreaded(1)) {
/* Use CAS to avoid losing a hash code due to a conflict with
JIT-generated `list?' test, which itself uses CAS to set "is
a list" or "not a list" flags on pairs. */

4
src/racket/src/jitcommon.c
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@ -2530,7 +2530,7 @@ static int common7(mz_jit_state *jitter, void *_data)
jit_ldxi_s(JIT_R2, JIT_R1, &MZ_OPT_HASH_KEY(&((Scheme_Stx *)0x0)->iso));
#ifdef MZ_USE_FUTURES
if (scheme_is_multiprocessor(0)) {
if (scheme_is_multithreaded(0)) {
/* Need an atomic update in case another thread is setting
a hash code on the target pair. */
ref5 = jit_bmsi_i(jit_forward(), JIT_R2, PAIR_IS_LIST);
@ -2567,7 +2567,7 @@ static int common7(mz_jit_state *jitter, void *_data)
jit_ldxi_s(JIT_R2, JIT_R1, &MZ_OPT_HASH_KEY(&((Scheme_Stx *)0x0)->iso));
#ifdef MZ_USE_FUTURES
/* As above: */
if (scheme_is_multiprocessor(0)) {
if (scheme_is_multithreaded(0)) {
ref5 = jit_bmsi_i(jit_forward(), JIT_R2, PAIR_IS_NON_LIST);
jit_movr_i(JIT_R0, JIT_R2);
jit_ori_i(JIT_R2, JIT_R2, PAIR_IS_NON_LIST);

2
src/racket/src/jitinline.c
View File

@ -3318,7 +3318,7 @@ int scheme_generate_inlined_nary(mz_jit_state *jitter, Scheme_App_Rec *app, int
/* This is the actual CAS: */
#ifdef MZ_USE_FUTURES
if (scheme_is_multiprocessor(0)) {
if (scheme_is_multithreaded(0)) {
jit_lock_cmpxchgr_l(JIT_R1, JIT_V1); /* implicitly uses JIT_R0 */
reffalse = (JNEm(jit_forward(), 0,0,0), _jit.x.pc);
} else

2
src/racket/src/schpriv.h
View File

@ -303,7 +303,7 @@ void scheme_free_dynamic_extensions(void);
void scheme_free_all_code(void);
void scheme_free_ghbn_data(void);
XFORM_NONGCING int scheme_is_multiprocessor(int now);
XFORM_NONGCING int scheme_is_multithreaded(int now);
/* Type readers & writers for compiled code data */
typedef Scheme_Object *(*Scheme_Type_Reader)(Scheme_Object *list);