Instead of a separate context-switch flag, set HpLim to zero

[ghc-hetmet.git] / rts / HeapStackCheck.cmm

diff --git a/rts/HeapStackCheck.cmm b/rts/HeapStackCheck.cmm
index 94cec38..10baca2 100644 (file)
--- a/rts/HeapStackCheck.cmm
+++ b/rts/HeapStackCheck.cmm
@@ -23,8 +23,11 @@ import LeaveCriticalSection;
  *
  * On discovering that a stack or heap check has failed, we do the following:
  *
- *    - If the context_switch flag is set, indicating that there are more
- *      threads waiting to run, we yield to the scheduler 
+ *    - If HpLim==0, indicating that we should context-switch, we yield
+ *      to the scheduler (return ThreadYielding).
+ *
+ *    - If the context_switch flag is set (the backup plan if setting HpLim
+ *      to 0 didn't trigger a context switch), we yield to the scheduler
  *     (return ThreadYielding).
  *
  *    - If Hp > HpLim, we've had a heap check failure.  This means we've
@@ -60,6 +63,10 @@ import LeaveCriticalSection;
 #define GC_GENERIC                                             \
     DEBUG_ONLY(foreign "C" heapCheckFail());                   \
     if (Hp > HpLim) {                                          \
+        if (HpLim == 0) { \
+                R1 = ThreadYielding;                           \
+                goto sched;                                    \
+        }                                              \
         Hp = Hp - HpAlloc/*in bytes*/;                         \
         if (HpAlloc <= BLOCK_SIZE                              \
             && bdescr_link(CurrentNursery) != NULL) {          \