MAYBE_GC: initialise HpAlloc

HpAlloc was not being set when returning to the scheduler via MAYBE_GC(),
which at the least was just wrong (the scheduler might allocate a large
block more than once), and at worst could lead to crashes if HpAlloc contains
garbage.

Fixes at least one threaded2 test on Windows.

diff --git a/includes/Cmm.h b/includes/Cmm.h
index e494b60..3d3283e 100644 (file)
--- a/includes/Cmm.h
+++ b/includes/Cmm.h
@@ -328,6 +328,7 @@
   if (bdescr_link(CurrentNursery) == NULL || CInt[alloc_blocks] >= CInt[alloc_blocks_lim]) {           \
        R9  = liveness;                                 \
         R10 = reentry;                                 \
+        HpAlloc = 0;                                   \
         jump stg_gc_gen_hp;                            \
    }