X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=rts%2FHeapStackCheck.cmm;h=a1b6d65f34f6e611b67bb1cbd05dcba0683e041a;hb=de75026f5a48d3d052135a973ab4dff76c5b20f5;hp=333d0c09e072dcc83cd77ff9fd9e5f16ce445992;hpb=1ed01a871030f05905a9595e4837dfffc087ef64;p=ghc-hetmet.git

diff --git a/rts/HeapStackCheck.cmm b/rts/HeapStackCheck.cmm
index 333d0c0..a1b6d65 100644
--- a/rts/HeapStackCheck.cmm
+++ b/rts/HeapStackCheck.cmm
@@ -23,8 +23,22 @@ 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).
+ *
+ * Note that we must leave no slop in the heap (this is a requirement
+ * for LDV profiling, at least), so if we just had a heap-check
+ * failure, then we must retract Hp by HpAlloc.  How do we know
+ * whether there was a heap-check failure?  HpLim might be zero, and
+ * yet we got here as a result of a stack-check failure.  Hence, we
+ * require that HpAlloc is only non-zero if there was a heap-check
+ * failure, otherwise it is zero, so we can always safely subtract
+ * HpAlloc from Hp.
+ *
+ * Hence, HpAlloc is zeroed in LOAD_THREAD_STATE().
+ *
+ *    - 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
@@ -61,12 +75,17 @@ import LeaveCriticalSection;
     DEBUG_ONLY(foreign "C" heapCheckFail());			\
     if (Hp > HpLim) {						\
         Hp = Hp - HpAlloc/*in bytes*/;				\
+        if (HpLim == 0) { \
+                R1 = ThreadYielding;				\
+                goto sched;					\
+        }						\
         if (HpAlloc <= BLOCK_SIZE				\
             && bdescr_link(CurrentNursery) != NULL) {		\
+            HpAlloc = 0;                                        \
             CLOSE_NURSERY();					\
             CurrentNursery = bdescr_link(CurrentNursery);	\
             OPEN_NURSERY();					\
-            if (CInt[context_switch] != 0 :: CInt) {		\
+            if (Capability_context_switch(MyCapability()) != 0 :: CInt) { \
                 R1 = ThreadYielding;				\
                 goto sched;					\
             } else {						\
@@ -114,7 +133,7 @@ import LeaveCriticalSection;
    There are canned sequences for 'n' pointer values in registers.
    -------------------------------------------------------------------------- */
 
-INFO_TABLE_RET( stg_enter, RET_SMALL, "ptr" W_ unused)
+INFO_TABLE_RET( stg_enter, RET_SMALL, P_ unused)
 {
     R1 = Sp(1);
     Sp_adj(2);
@@ -444,7 +463,7 @@ INFO_TABLE_RET( stg_gc_void, RET_SMALL)
 
 /*-- R1 is boxed/unpointed -------------------------------------------------- */
 
-INFO_TABLE_RET( stg_gc_unpt_r1, RET_SMALL, "ptr" W_ unused)
+INFO_TABLE_RET( stg_gc_unpt_r1, RET_SMALL, P_ unused)
 {
     R1 = Sp(1);
     Sp_adj(2);
@@ -531,7 +550,7 @@ stg_gc_l1
 
 /*-- Unboxed tuple return, one pointer (unregisterised build only) ---------- */
 
-INFO_TABLE_RET( stg_ut_1_0_unreg, RET_SMALL, "ptr" W_ unused )
+INFO_TABLE_RET( stg_ut_1_0_unreg, RET_SMALL, P_ unused )
 {
     Sp_adj(1);
     // one ptr is on the stack (Sp(0))
@@ -816,7 +835,7 @@ stg_block_1
  * 
  * -------------------------------------------------------------------------- */
 
-INFO_TABLE_RET( stg_block_takemvar, RET_SMALL, "ptr" W_ unused )
+INFO_TABLE_RET( stg_block_takemvar, RET_SMALL, P_ unused )
 {
     R1 = Sp(1);
     Sp_adj(2);
@@ -843,7 +862,7 @@ stg_block_takemvar
     BLOCK_BUT_FIRST(stg_block_takemvar_finally);
 }
 
-INFO_TABLE_RET( stg_block_putmvar, RET_SMALL, "ptr" W_ unused1, "ptr" W_ unused2 )
+INFO_TABLE_RET( stg_block_putmvar, RET_SMALL, P_ unused1, P_ unused2 )
 {
     R2 = Sp(2);
     R1 = Sp(1);
@@ -892,7 +911,7 @@ stg_block_blackhole
     BLOCK_BUT_FIRST(stg_block_blackhole_finally);
 }
 
-INFO_TABLE_RET( stg_block_throwto, RET_SMALL, "ptr" W_ unused, "ptr" W_ unused )
+INFO_TABLE_RET( stg_block_throwto, RET_SMALL, P_ unused, P_ unused )
 {
     R2 = Sp(2);
     R1 = Sp(1);