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runtime: use new CNT_MASK in lfstack

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This is for SPARC64, a 64-bit processor that uses all 64-bits
of virtual addresses.  The idea is to use the low order 3 bits
to at least get a small ABA counter.  That should work since
pointers are aligned.  The idea is for SPARC64 to set CNT_MASK
== 7, PTR_BITS == 0, PTR_MASK == 0xffffffffffffff8.

Also add uintptr casts to avoid GCC warnings.  The gccgo
runtime code is compiled with GCC, and GCC warns when casting
between a pointer and a type of a different size.

R=dvyukov
CC=golang-dev
https://golang.org/cl/7225043
This commit is contained in:
Ian Lance Taylor 2013-01-26 18:16:43 -08:00
parent 75104237c8
commit e65c0a82ce
1 changed files with 6 additions and 5 deletions
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11
src/pkg/runtime/lfstack.c
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@ -15,22 +15,23 @@
# define PTR_BITS 32
#endif
#define PTR_MASK ((1ull<<PTR_BITS)-1)
#define CNT_MASK (0ull-1)
void
runtime·lfstackpush(uint64 *head, LFNode *node)
{
uint64 old, new;
if((uint64)node != ((uint64)node&PTR_MASK)) {
if((uintptr)node != ((uintptr)node&PTR_MASK)) {
runtime·printf("p=%p\n", node);
runtime·throw("runtime·lfstackpush: invalid pointer");
}
node->pushcnt++;
new = (uint64)node|(((uint64)node->pushcnt)<<PTR_BITS);
new = (uint64)(uintptr)node|(((uint64)node->pushcnt&CNT_MASK)<<PTR_BITS);
old = runtime·atomicload64(head);
for(;;) {
node->next = (LFNode*)(old&PTR_MASK);
node->next = (LFNode*)(uintptr)(old&PTR_MASK);
if(runtime·cas64(head, &old, new))
break;
}
@ -46,11 +47,11 @@ runtime·lfstackpop(uint64 *head)
for(;;) {
if(old == 0)
return nil;
node = (LFNode*)(old&PTR_MASK);
node = (LFNode*)(uintptr)(old&PTR_MASK);
node2 = runtime·atomicloadp(&node->next);
new = 0;
if(node2 != nil)
new = (uint64)node2|(((uint64)node2->pushcnt)<<PTR_BITS);
new = (uint64)(uintptr)node2|(((uint64)node2->pushcnt&CNT_MASK)<<PTR_BITS);
if(runtime·cas64(head, &old, new))
return node;
}