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runtime: hide the semaphore table from garbage collector

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R=rsc, dvyukov, dave
CC=golang-dev
https://golang.org/cl/6528043
This commit is contained in:
Jan Ziak 2012-09-18 14:30:01 -04:00 committed by Russ Cox
parent 8c058b32d1
commit 35724c1aa5
1 changed files with 5 additions and 3 deletions
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8
src/pkg/runtime/sema.goc
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@ -43,11 +43,13 @@ struct SemaRoot
// Prime to not correlate with any user patterns. // Prime to not correlate with any user patterns.
#define SEMTABLESZ 251 #define SEMTABLESZ 251
static union union semtable
{ {
SemaRoot; SemaRoot;
uint8 pad[CacheLineSize]; uint8 pad[CacheLineSize];
} semtable[SEMTABLESZ]; };
#pragma dataflag 16 /* mark semtable as 'no pointers', hiding from garbage collector */
static union semtable semtable[SEMTABLESZ];
static SemaRoot* static SemaRoot*
semroot(uint32 *addr) semroot(uint32 *addr)
@ -98,7 +100,7 @@ cansemacquire(uint32 *addr)
void void
runtime·semacquire(uint32 volatile *addr) runtime·semacquire(uint32 volatile *addr)
{ {
Sema s; Sema s; // Needs to be allocated on stack, otherwise garbage collector could deallocate it
SemaRoot *root; SemaRoot *root;
// Easy case. // Easy case.