Tweak ABI & add moxie-uclinux target.

[pf3gnuchains/gcc-fork.git] / gcc / cfgcleanup.c

diff --git a/gcc/cfgcleanup.c b/gcc/cfgcleanup.c
index 757a0ff..c631907 100644 (file)
--- a/gcc/cfgcleanup.c
+++ b/gcc/cfgcleanup.c
@@ -953,7 +953,12 @@ old_insns_match_p (int mode ATTRIBUTE_UNUSED, rtx i1, rtx i2)
   if (GET_CODE (i1) != GET_CODE (i2))
     return false;
 
-  p1 = PATTERN (i1);
+  /* __builtin_unreachable() may lead to empty blocks (ending with
+     NOTE_INSN_BASIC_BLOCK).  They may be crossjumped. */
+  if (NOTE_INSN_BASIC_BLOCK_P (i1) && NOTE_INSN_BASIC_BLOCK_P (i2))
+    return true;
+
+   p1 = PATTERN (i1);
   p2 = PATTERN (i2);
 
   if (GET_CODE (p1) != GET_CODE (p2))
@@ -1841,10 +1846,16 @@ try_optimize_cfg (int mode)
 
              /* Delete trivially dead basic blocks.  This is either
                 blocks with no predecessors, or empty blocks with no
-                successors.  Empty blocks may result from expanding
+                successors.  However if the empty block with no
+                successors is the successor of the ENTRY_BLOCK, it is
+                kept.  This ensures that the ENTRY_BLOCK will have a
+                successor which is a precondition for many RTL
+                passes.  Empty blocks may result from expanding
                 __builtin_unreachable ().  */
              if (EDGE_COUNT (b->preds) == 0
-                 || (EDGE_COUNT (b->succs) == 0 && BB_HEAD (b) == BB_END (b)))
+                 || (EDGE_COUNT (b->succs) == 0
+                     && BB_HEAD (b) == BB_END (b)
+                     && single_succ_edge (ENTRY_BLOCK_PTR)->dest != b))
                {
                  c = b->prev_bb;
                  if (dump_file)
@@ -1916,6 +1927,7 @@ try_optimize_cfg (int mode)
                  delete_basic_block (b);
                  changed = true;
                  b = c;
+                 continue;
                }
 
              if (single_succ_p (b)