> This exposed a couple of similar bugs in cse.c and postreload-gcse.c: the
> code was effectively treating a basic block with a single, abnormal
> incoming edge as if the edge was normal.

I've installed the following refined fix, after testing on i586-suse-linux and 
sparc-sun-solaris2.10.  Most EDGE_ABNORMAL edges can very likely be treated 
normally here, for example EH edges when call-saved registers are considered.
The only really problematic ones are EDGE_ABNORMAL_CALL edges when there is a 
non-local label in the function, because even call-saved registers are not 
guaranteed to be preserved in this case.


2011-06-02  Eric Botcazou  <ebotca...@adacore.com>

        * cse.c (cse_find_path): Refine change to exclude EDGE_ABNORMAL_CALL
        edges only, when there is a non-local label in the function.
        * postreload-gcse.c (bb_has_well_behaved_predecessors): Likewise.


-- 
Eric Botcazou
Index: cse.c
===================================================================
--- cse.c	(revision 174564)
+++ cse.c	(working copy)
@@ -6193,7 +6193,7 @@ cse_find_path (basic_block first_bb, str
 	    e = NULL;
 
 	  if (e
-	      && (e->flags & EDGE_ABNORMAL) == 0
+	      && !((e->flags & EDGE_ABNORMAL_CALL) && cfun->has_nonlocal_label)
 	      && e->dest != EXIT_BLOCK_PTR
 	      && single_pred_p (e->dest)
 	      /* Avoid visiting basic blocks twice.  The large comment
Index: postreload-gcse.c
===================================================================
--- postreload-gcse.c	(revision 174564)
+++ postreload-gcse.c	(working copy)
@@ -912,12 +912,10 @@ get_avail_load_store_reg (rtx insn)
 static bool
 bb_has_well_behaved_predecessors (basic_block bb)
 {
-  unsigned int edge_count = EDGE_COUNT (bb->preds);
   edge pred;
   edge_iterator ei;
 
-  if (edge_count == 0
-      || (edge_count == 1 && (single_pred_edge (bb)->flags & EDGE_ABNORMAL)))
+  if (EDGE_COUNT (bb->preds) == 0)
     return false;
 
   FOR_EACH_EDGE (pred, ei, bb->preds)
@@ -925,6 +923,9 @@ bb_has_well_behaved_predecessors (basic_
       if ((pred->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (pred))
 	return false;
 
+      if ((pred->flags & EDGE_ABNORMAL_CALL) && cfun->has_nonlocal_label)
+	return false;
+
       if (JUMP_TABLE_DATA_P (BB_END (pred->src)))
 	return false;
     }

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