[Git][ghc/ghc][wip/tsan/prep] 3 commits: rts: Introduce more principled fence operations

[Ben Gamari (@bgamari)]

Ben Gamari pushed to branch wip/tsan/prep at Glasgow Haskell Compiler / GHC


Commits:
afdc15ea by Ben Gamari at 2023-07-24T14:13:28-04:00
rts: Introduce more principled fence operations

- - - - -
6bdb0bce by Ben Gamari at 2023-07-24T14:14:02-04:00
rts: Introduce SET_INFO_RELAXED

- - - - -
af672b66 by Ben Gamari at 2023-07-24T14:14:11-04:00
rts: Fix unsupported fence warnings with TSAN

- - - - -


3 changed files:

- rts/include/Cmm.h
- rts/include/rts/storage/ClosureMacros.h
- rts/include/stg/SMP.h


Changes:

=====================================
rts/include/Cmm.h
=====================================
@@ -596,6 +596,7 @@
 /* Getting/setting the info pointer of a closure */
 #define SET_INFO(p,info) StgHeader_info(p) = info
 #define SET_INFO_RELEASE(p,info) %release StgHeader_info(p) = info
+#define SET_INFO_RELAXED(p,info) %relaxed StgHeader_info(p) = info
 #define GET_INFO(p) StgHeader_info(p)
 #define GET_INFO_ACQUIRE(p) %acquire GET_INFO(p)
 
@@ -687,10 +688,18 @@
 #define RELEASE_FENCE prim %fence_release();
 #define ACQUIRE_FENCE prim %fence_acquire();
 
+// TODO
+#if 1
+#define ACQUIRE_FENCE_ON(x) if (1) { W_ tmp; (tmp) = prim %load_acquire64(x); }
+#else
+#define ACQUIRE_FENCE_ON(x) ACQUIRE_FENCE
+#endif
+
 #else
 
 #define RELEASE_FENCE /* nothing */
 #define ACQUIRE_FENCE /* nothing */
+#define ACQUIRE_FENCE_ON(x) /* nothing */
 #endif /* THREADED_RTS */
 
 /* -----------------------------------------------------------------------------


=====================================
rts/include/rts/storage/ClosureMacros.h
=====================================
@@ -47,6 +47,11 @@
 
 EXTERN_INLINE void SET_INFO(StgClosure *c, const StgInfoTable *info);
 EXTERN_INLINE void SET_INFO(StgClosure *c, const StgInfoTable *info) {
+    c->header.info = info;
+}
+
+EXTERN_INLINE void SET_INFO_RELAXED(StgClosure *c, const StgInfoTable *info);
+EXTERN_INLINE void SET_INFO_RELAXED(StgClosure *c, const StgInfoTable *info) {
     RELAXED_STORE(&c->header.info, info);
 }
 
@@ -70,6 +75,7 @@ EXTERN_INLINE StgThunkInfoTable *itbl_to_thunk_itbl     (const StgInfoTable *i);
 EXTERN_INLINE StgConInfoTable   *itbl_to_con_itbl       (const StgInfoTable *i);
 
 #if defined(TABLES_NEXT_TO_CODE)
+NO_WARN(-Warray-bounds,
 EXTERN_INLINE StgInfoTable *INFO_PTR_TO_STRUCT(const StgInfoTable *info) {return (StgInfoTable *)info - 1;}
 EXTERN_INLINE StgRetInfoTable *RET_INFO_PTR_TO_STRUCT(const StgInfoTable *info) {return (StgRetInfoTable *)info - 1;}
 EXTERN_INLINE StgFunInfoTable *FUN_INFO_PTR_TO_STRUCT(const StgInfoTable *info) {return (StgFunInfoTable *)info - 1;}
@@ -79,6 +85,7 @@ EXTERN_INLINE StgFunInfoTable *itbl_to_fun_itbl(const StgInfoTable *i) {return (
 EXTERN_INLINE StgRetInfoTable *itbl_to_ret_itbl(const StgInfoTable *i) {return (StgRetInfoTable *)(i + 1) - 1;}
 EXTERN_INLINE StgThunkInfoTable *itbl_to_thunk_itbl(const StgInfoTable *i) {return (StgThunkInfoTable *)(i + 1) - 1;}
 EXTERN_INLINE StgConInfoTable *itbl_to_con_itbl(const StgInfoTable *i) {return (StgConInfoTable *)(i + 1) - 1;}
+)
 #else
 EXTERN_INLINE StgInfoTable *INFO_PTR_TO_STRUCT(const StgInfoTable *info) {return (StgInfoTable *)info;}
 EXTERN_INLINE StgRetInfoTable *RET_INFO_PTR_TO_STRUCT(const StgInfoTable *info) {return (StgRetInfoTable *)info;}


=====================================
rts/include/stg/SMP.h
=====================================
@@ -490,10 +490,25 @@ busy_wait_nop(void)
 // These are typically necessary only in very specific cases (e.g. WSDeque)
 // where the ordered operations aren't expressive enough to capture the desired
 // ordering.
+//
+// Additionally, it is preferable to use the *_FENCE_ON() forms, which turn into
+// memory accesses when compiling for ThreadSanitizer (as ThreadSanitizer is
+// otherwise unable to reason about fences). See Note [ThreadSanitizer] in
+// TSANUtils.h.
+
 #define ACQUIRE_FENCE() __atomic_thread_fence(__ATOMIC_ACQUIRE)
 #define RELEASE_FENCE() __atomic_thread_fence(__ATOMIC_RELEASE)
 #define SEQ_CST_FENCE() __atomic_thread_fence(__ATOMIC_SEQ_CST)
 
+#if defined(TSAN_ENABLED)
+#define ACQUIRE_FENCE() NO_WARN(-Wtsan, __atomic_thread_fence(__ATOMIC_ACQUIRE);)
+#define RELEASE_FENCE() NO_WARN(-Wtsan, __atomic_thread_fence(__ATOMIC_RELEASE);)
+#define SEQ_CST_FENCE() NO_WARN(-Wtsan, __atomic_thread_fence(__ATOMIC_SEQ_CST);)
+#define ACQUIRE_FENCE_ON(x) (void)ACQUIRE_LOAD(x)
+#else
+#define ACQUIRE_FENCE_ON(x) __atomic_thread_fence(__ATOMIC_ACQUIRE)
+#endif
+
 /* ---------------------------------------------------------------------- */
 #else /* !THREADED_RTS */
 
@@ -521,6 +536,8 @@ busy_wait_nop(void)
 #define ACQUIRE_FENCE()
 #define RELEASE_FENCE()
 #define SEQ_CST_FENCE()
+#define ACQUIRE_FENCE_ON(x)
+#define RELEASE_FENCE_ON(x)
 
 #if !IN_STG_CODE || IN_STGCRUN
 INLINE_HEADER StgWord



View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/04b2fc724b86703c619d55f17c7047efdf297b8c...af672b6669059a8df0e04cbd2b2959d0390830fb

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/04b2fc724b86703c619d55f17c7047efdf297b8c...af672b6669059a8df0e04cbd2b2959d0390830fb
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