Fix 'statement unreachable' compiler warning in GC_mark_from

* mark.c (GC_mark_from): Initialize 'limit' local variable
unconditionally; add static assertion on GC_DS_TAGS (to check that it
corresponds to number of switch cases); remove switch default (as it
cannot happen).

diff --git a/mark.c b/mark.c
index 5cb3fedeb32e0dd4e110047ebb38de66039e0b8b..effe76509bc4756e518a209ae56dd216b0ac0f1a 100644 (file)
--- a/mark.c
+++ b/mark.c
@@ -609,9 +609,9 @@ GC_INNER mse * GC_mark_from(mse *mark_stack_top, mse *mark_stack,
                             mse *mark_stack_limit)
 {
   signed_word credit = HBLKSIZE;  /* Remaining credit for marking work  */
-  ptr_t current_p;      /* Pointer to current candidate ptr.    */
-  word current; /* Candidate pointer.                           */
-  ptr_t limit;  /* (Incl) limit of current candidate range.     */
+  ptr_t current_p;      /* Pointer to current candidate ptr.            */
+  word current;         /* Candidate pointer.                           */
+  ptr_t limit = 0;      /* (Incl) limit of current candidate range.     */
   word descr;
   ptr_t greatest_ha = GC_greatest_plausible_heap_addr;
   ptr_t least_ha = GC_least_plausible_heap_addr;
@@ -638,6 +638,7 @@ GC_INNER mse * GC_mark_from(mse *mark_stack_top, mse *mark_stack,
     if (descr & ((~(WORDS_TO_BYTES(SPLIT_RANGE_WORDS) - 1)) | GC_DS_TAGS)) {
       word tag = descr & GC_DS_TAGS;
 
+      GC_STATIC_ASSERT(GC_DS_TAGS == 0x3);
       switch(tag) {
         case GC_DS_LENGTH:
           /* Large length.                                              */
@@ -769,9 +770,6 @@ GC_INNER mse * GC_mark_from(mse *mark_stack_top, mse *mark_stack,
               continue;
           }
           goto retry;
-        default:
-          limit = 0; /* initialized to prevent warning. */
-          ABORT_RET("GC_mark_from: bad state");
       }
     } else /* Small object with length descriptor */ {
       mark_stack_top--;