Improve accuracy of get/setAllocationCounter

Summary:
get/setAllocationCounter didn't take into account allocations in the
current block. This was known at the time, but it turns out to be
important to have more accuracy when using these in a fine-grained
way.

Test Plan:
New unit test to test incrementally larger allocaitons.  Before I got
results like this:

```
+0
+0
+0
+0
+0
+4096
+0
+0
+0
+0
+0
+4064
+0
+0
+4088
+4056
+0
+0
+0
+4088
+4096
+4056
+4096
```

Notice how the results aren't always monotonically increasing.  After
this patch:

```
+344
+416
+488
+560
+632
+704
+776
+848
+920
+992
+1064
+1136
+1208
+1280
+1352
+1424
+1496
+1568
+1640
+1712
+1784
+1856
+1928
+2000
+2072
+2144
```

Reviewers: niteria, bgamari, hvr, erikd

Subscribers: rwbarton, thomie, carter

Differential Revision: https://phabricator.haskell.org/D4288

1 files changed, 1 insertions, 12 deletions

diff --git a/rts/Threads.c b/rts/Threads.c
index b09dfa8ccc..c54156f383 100644
--- a/rts/Threads.c
+++ b/rts/Threads.c
@@ -165,19 +165,8 @@ rts_getThreadId(StgPtr tso)
 }
 
 /* ---------------------------------------------------------------------------
- * Getting & setting the thread allocation limit
+ * Enabling and disabling the thread allocation limit
  * ------------------------------------------------------------------------ */
-HsInt64 rts_getThreadAllocationCounter(StgPtr tso)
-{
-    // NB. doesn't take into account allocation in the current nursery
-    // block, so it might be off by up to 4k.
-    return PK_Int64((W_*)&(((StgTSO *)tso)->alloc_limit));
-}
-
-void rts_setThreadAllocationCounter(StgPtr tso, HsInt64 i)
-{
-    ASSIGN_Int64((W_*)&(((StgTSO *)tso)->alloc_limit), i);
-}
 
 void rts_enableThreadAllocationLimit(StgPtr tso)
 {